bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study on the Corrosion Fatigue Characteristics of Al 2024-T3 Alloy
Authors: Duan Rui Chun , Shi Hui Ji
Published: March 2009

In order to investigate how the corrosion dramatically reduces fatigue resistance of a 2024-T3 aluminium alloy, a series of corrosion experiments in a 3.5 wt% NaCl solution with different steeping time, and subsequent fatigue experiments under uniaxial cyclic load have been performed with the laminate specimens. The nucleation and growth of corrosion pits are found to occur mainly at the grain boundary. The optical micrographs of the experiments show that the fatigue micro-crack initiates on the bottom of the pit, expands its way through the neighbouring pits that located at the slip direction and then forms a main fatigue crack that leads to fracture. The similar corrosion experiments are also performed at different solution temperatures: 22 °C, 40°C, 60°C, and 80°C respectively. The effects of the steeping time and solution temperature on the fatigue life are investigated.
Effect of Initial Porosity on Mechanical Properties of C/SiC Composites Fabricated by Silicon Melt Infiltration Process
Authors: Bae Dong Su , Son Dong Young , Lee Sang Ll , Park Hong Sik , Kim Kwang Soo , Jeon Jae Ho
Published: March 2009

Four kinds of raw C/C composites with a density between 1.25~1.66g/㎤ were used in order to investigate the effect of the initial porosity of C/C composites on mechanical properties of liquid silicon infiltrated C/SiC composites. The microstructure observation, image analysis and flexural strength test of the composites were performed. The density and microstructural changes with the variation of the initial porosity was discussed in the terms of the infiltration behavior of liquid silicon and the reaction between liquid silicon and matrix carbon.
Characteristics of Laser Speckle Measurement of Tooth Roughness
Authors: Uchino M. , Fujisaki W. , Kurihara E. , Matsuda K. , Koseki Toshihiko
Published: March 2009

This study is concerned with the fundamental characteristics of a new nondestructive measuring technique of the tooth roughness with precisely. In the dental clinics, the estimation of roughness of tooth surfaces with a hand explorer is one of the important tests for the finishing the crown re-shaping and resin fillings. If the tooth surface is rough enough to hold dental plaque, it occasio-nally causes dental diseases around it. Therefore, it is important to measure the roughness of the tooth surfaces for the prevention of furthermore distraction of the tooth. Laser speckle measurement is used as an evaluation method for objectively measuring the surface roughness with non-contact. In this study, a laser speckle measurement system for measuring the surface roughness is constructed. Comparison measurement is carried out for the tooth pieces with the various unidirectional roughness and the metallic test pieces with the standard roughness. The experimental results using the actual measuring system show some important points as follows. Firstly, there is a good correla-tion between the laser speckle pattern and the tooth roughness as well as that of the metallic test pieces. Secondly, the reflection from the tooth shows a different tendency in comparison with the reflection from the metallic test pieces.
The Bending Strength of Brittle Materials and the Characteristics of the Elastic Wave Signal by Vickers Indentation
Authors: Ahn Seok Hwan , Nam Ki Woo , Ando Kotoji
Published: March 2009

Four kinds of brittle materials were used to evaluate the bending strength under three-point bending and the characteristics of the elastic wave signal by Vickers indentation. The bending test was carried out under room temperature and high temperature. A crack was made at the tension side of the specimen with a Vickers indenter to investigate fracture strength. Fracture wave detector was used to evaluate characteristics of waveform and frequency of the elastic wave signal.
Anisotropic and Isotropic Elasticity, and its Equivalence for Singularity, Interface and Crack in Bimaterials and Trimaterials
Authors: Earmme Y.Y. , Choi S.T. , Shin H.
Published: March 2009

The equivalence between anisotropic and isotropic elasticity is investigated in this study for two-dimensional deformation under certain conditions. That is, the isotropic elasticity can be reconstructed in the same framework of the anisotropic elasticity, when the interface between dissimilar media lies along a straight line. Therefore, many known solutions for an anisotropic bimaterial can be regarded as valid even for a bimaterial, in which one or both of the constituent materials are isotropic. The usefulness of the equivalence is that the solutions for singularities and cracks in an anisotropic/isotropic bimaterial can easily be obtained without solving the boundary
value problems directly. Conservation integrals also have the similar analogy between anisotropic and isotropic elasticity so that J integral and J-based mutual integral M are expressed in the same complex forms for anisotropic and isotropic materials, when both end points of the integration paths are on the straight interface.
The method of analytic continuation and Schwarz-Neumann's alternating technique are applied to singularity problems in an anisotropic or isotropic 'trimaterial', which denotes an infinite body composed of three dissimilar materials bonded along two parallel interfaces. The method of analytic continuation is alternatively applied across the two parallel interfaces in order to derive the trimaterial solution in a series form from the corresponding homogeneous solution. The trimaterial solution studied here can be applied to a variety of problems, e.g. a bimaterial (including a half-plane problem), a finite thin film on semi-infinite substrate, and a finite strip of thin film, etc. Some examples are presented to verify the usefulness of the obtained solutions.
Numerical Simulations of Failure of Brittle Solids under Dynamic Impact Using a New Computer Program - DIFAR
Authors: Chau K.T. , Zhu Wan Cheng , Tang Chun An , Wu S.Z.
Published: March 2009

This paper presents a new computer program called DIFAR (or dynamic incremental failure analysis of rock) that can simulate fracture process of brittle rocks under dynamic impacts. The program is based on a linear elastic finite element method incorporated with a failure criterion for damage checking. Modulus is reduced once the failure criterion is satisfied. In addition, Weibull distribution of the modulus and strength of the elements are used for modeling the mesoscopic
heterogeneity. The failure criterion is a Mohr-Coulomb type of condition with a tensile cut-off, in which strength parameters are functions of the strain rate. More importantly, the whole fracture process of rock fragmentation can be simulated, including initiation, propagation, and coalescence of microcracks. The program DIFAR has been used to simulate elastic wave propagation and nonlinear fragmentation, and validity and efficiency of this program is demonstrated. The program can be considered as a dynamic counterpart of the RFPA, a failure analysis program for static loads, developed at Northeastern University, China.
Study on the Mechanical Properties of Soft Rock under Dynamic Uniaxial Compression
Authors: Li Hai Bo , Li Jun Ru , Zhou Qing Chun , Liu Yong Qiang , Xia X.
Published: March 2009

The present paper introduces the experimental study on soft rock (analogized with mortar)under dynamic uniaxial compression at the strain rates from 10
-5 to 101s-1. It is indicated that thecompressive strength of the soft rock increase with the increasing strain rate and the rising rates are
higher than that of hard rock. The Young's moduli and Poisson's ratio of the soft rock increase with the increasing strain rate, but the rising rates are less than that of compressive strength. In addition, the mechanism of the strain rate effect of the soft rock is primarily analyzed based on the SEM results.
Fragmentation of Kidney Stone by Shock Wave-Experimental Approach
Authors: Homma Hiroomi , Mihradi Sandro , Takeuchi Takenori
Published: March 2009

To understand fundamentals of kidney stone™s fragmentation by shock wave impingement, experimental approach was carried out. Air gun system was used to transfer a well-controlled stress wave into a thin disk specimen. The specimen was fabricated with plaster and its dimensions are 10 mm in diameter and 1.2 mm in thickness. The obtained results are summarized as follows: As the stress pulse duration is decreased from 12 microseconds to 5 microseconds, the critical stress for fracture increased tremendously. The critical fracture stress for a specimen with a small hole in the specimen center is about one fifth of that for the plain specimen. The fracture takes place along the diameter perpendicular to the stress wave incident direction. Numerical stress analysis suggests that the principal stress criterion can explain the fracture mode.
Coating Interface Fracture Toughness Evaluation by a Combination of Edge Compression and Slinging Load
Authors: Arai Masayuki , Okajima Yoshifumi , Kishimoto Kikuo
Published: March 2009

Previous methods to measure interface fracture toughness between coating and substrate can't easily vary a phase angle as a mixed mode parameter. So that, the new coating interface fracture toughness test method, by which phase angle at interface crack tip can be varied due to applying a combination of compression loading to the coating edge and slinging such as beam bending, is proposed. The simple formula, which connects to complex stress intensity factors and double
loading is firstly derived on the basis of the cracked beam model proposed by Suo and Hutchinson [1]. As an application of the method and associated formula, thermal barrier coating/super-alloy interface toughness is evaluated based on numerical analysis.
Effect of Decarburized Layer of Tool Steel on Delamination Strength of WC-Co Thermally Sprayed Coating
Authors: Li Cheng Wei , Kato Masahiko , Nakasa Keijiro
Published: March 2009

Decarburization treatment was carried out on SKD5 tool steel by heating at 1323K for
maximum 5.4ks and quenching followed by tempering at 873K for 3.6ks. This resulted in decarburized layer of maximum thickness 0.45mm. After the treatment, WC-Co cermet of 0.2mm thickness was deposited by high-velocity oxygen fuel thermal spraying. Tensile tests were carried out on the specimens, where the load was applied parallel to the specimen. The results show that the presence of decarburized layer increases the interfacial fracture toughness. The reason seems to be that the large plastic deformation of decarburized layer relieves shear and tensile stresses at crack tip. Edge indent tests were also conducted, where shear delamination of coating occurred during the penetration of indenter. The result is that the delamination energy decreases due to the presence of decarburized layer, which is contrary to that of the tensile test. The shear fracture of soft decarburized layer may be the reason for the smaller delamination energy of decarburized specimen.
Dynamic Response of Multiple Coplanar Interface Cracks between Two Dissimilar Piezoelectric Materials
Authors: Feng Wen Jie , Zou Zhi Wen , Su R.K.L. , Zou Z.Z.
Published: March 2009

The linear piezoelectricity theory is applied to investigate the dynamic response of coplanar interface cracks between two dissimilar piezoelectric materials subjected to the mechanical and electrical impacts. The number of cracks is arbitrary, and the interface cracks are assumed to be permeable for electric field. Integral transforms and dislocation density function are employed to reduce the problem to Cauchy singular integral equations. Numerical examples are given to show the effects of crack relative position and material property parameters on the variations of dynamic
energy release rate.
Fracture and Crack Growth Resistance Behaviour of γ-Titanium Aluminide
Authors: Kumar Amar N.
Published: March 2009

Research activities on deformation and fracture characteristics of the Ti-Al intermetallics have assumed considerable significance in view of many potential applications as high temperature structural materials. These aspects are discussed in respect of two Ti-Al intermetallics with duplex and lamellar structures. The fracture toughness, crack growth resistance and fracture mechanisms are evaluated at room temperature. The differences in the behaviour of the alloys are explained in
the light of microstructures as observed for the alloys.
Analysis of Piezoelectric Fracture under Combined Mechanical and Electrical Loading based on Meshless Method
Authors: Guo Xiang Hua , Fang Dai Ning
Published: March 2009

In this paper, the moving least-square (MLS) method, one of the most promising meshless
methods, is modified to construct whole field meshless approximation for coupled
electromechanical problems. Based on this method, the crack propagation behavior and the
elasto-electric fields near a crack tip in a PZT-5H piezoelectric ceramic under mechanical, electrical
and mechanical-electrical mixed loads are investigated. The numerical results show that for a
negative applied electric field, the hoop stress will be maximum at a certain angle other than 00
when the ratio of the electric field to tensile stress is relatively high, which makes the crack turn
away from its original growth path.
Study on Finite Dynamic Element Method for Dynamic Consolidation
Authors: Song Xiu Guang , Ma Xiu Yuan , Liu Jin Zhang
Published: March 2009

Based on the conception of dynamic shape function, a finite dynamic element method (DEM) is developed for the computation of dynamic consolidation. Formulae of the DEM are also derived. This method overcomes the shortcomings of conventional finite element methods, i.e., the vibration characteristics of the soil to be consolidated cannot be considered. Therefore, it practically reflects the dynamic characteristics of consolidation. The programs for the DEM are also written. Results of practical calculation show that the method is correct and feasible.
A Study of Fine Blanking Process by FEM Simulation
Authors: Fang Gang , Zeng P.
Published: March 2009

Fine blanking process with V-ring was simulated with FEM. The geometric parameters of the die, the punch, the serrated ring and the sheet are modeled. In this paper, some other assumptions are made for the analysis. The workpiece is considered as elastic-plastic material, while the tools are defined as rigid bodies. The damage model taking into account the influence of hydrostatic stress is used to simulate material fracture in blanking. The stress status and forming process are analyzed. Authors also investigated the effect of distance from tooth to die edge on roll-over high. The simulation can reflect the laws of fine blanking process.
Elastic Buckling Strength of Restrained Orthotropic Web Plates
Authors: Jung Jae Ho , Yoon Soon Jong , You S.K.
Published: March 2009

In this paper, the buckling behavior of elastically restrained orthotropic web plates is
investigated. In general, the pultruded FRP structural member is composed of flat plate elements and each plate element is elastically restrained against rotation by adjacent plate components. For finding the local buckling strength of composite flexural member considering the elastic restraint at the juncture of plate components, the orthotropic web plate is modeled as an elastically restrained orthotropic plate under linearly distributed in-plane forces. For the derivation of buckling equation,
the power series solution technique is employed. For the plate having different mechanical properties, the parametric studies are conducted by varying the degree of restraint along the longitudinal edge under compression. By using the results obtained, simplified form of equation is also developed so that the practicing engineers can evaluate the buckling stress of such a plate for the preliminary design of FRP flexural members.
An Elliptical Crack in a Thermopiezoelectric Solid under Uniform Temperature Gradient: Analytical Development
Authors: Shang F. , Kuna Meinhard , Kitamura Takayuki
Published: March 2009

An elliptical crack subjected to uniform temperature gradient in an infinite thermopiezoelectric solid is investigated in this work. Theoretical attempt has been made to find the temperature and piezoelectric fields at first by using a potential function formulation. The field intensity factors due to the thermal disturbance are obtained, as well as the local fields of the stresses and electric displacements near the crack front.
On Fracture Analysis Using an Element Overlay Technique
Authors: Okada Hiroshi , Endoh S. , Kikuchi Masanori
Published: March 2009

In this paper, a simple but highly accurate analytical method to evaluate stress intensity factors based on an element overlay technique is presented. When a crack exists in a structure, we need to analyze its global deformation as well as local deformation field around the tip of the crack. This naturally leads us to a consideration on some kind of multi-scale analysis strategies. Thus, we adopt the element overlay technique (S-FEM) which is a kind of multi-scale methodologies.
In this paper, we present i) numerical implementation of element overlay technique (S-FEM), ii) method to calculate stress intensity factors (virtual crack closure-integral method, VCCM), iii)accuracies of evaluated stress intensity factors and iv) some discussions.
Re-Evaluation of Dynamical Models of Buildings Using Identification Techniques
Authors: Atanasiu Gabriela Maria
Published: March 2009

Damage evaluation of constructions, subjected to earthquakes is an issue focused by many researchers, being a complicated matter. It is based on a multiple stage concept, depending on the level of understanding of the problem hierarchy for a requested safety level, based on structural performances. The structural modeling for simulations of lifetime constructions' behavior to seismic loads takes is a computational multiphase process based on the following stages: a priori modeling for initial design, on line monitoring of structure during lifetime functioning, damage
identification and model re-evaluation. Recent results of research in computational earthquake engineering highlights the real need for re-evaluation of dynamical models of constructions, after they have experienced several seismic events. The re-evaluation should be based on their real engineering performance of the structure experience during several earthquakes.
The paper deals with the problem of structural model's re-evaluation using some experimental available data. The purpose of re-evaluation is to increase the seismic safety of damaged existing buildings located in seismic high-risk areas. The correction of structural models for damaged constructions is based on a deterministic procedure. The methodology used for structural models' adjustment is exposed below, being validated by a study case done on a frame model of a reinforced 3 stories frame construction.
A Study on the Analysis and Design of Grillages under a Worst Point Load
Authors: Kim Ki Sung , Kim Kyung Su , Park Hyoung Jin
Published: March 2009

Grillage is common types of structures in marine and land-based structural system.
Grillage system that increases the stiffness of plate used by two rectangular stiffeners is a part of deck, side shell and bottom of ships.
The worst load point of those structures is dependent on the loads, which are vertical, in-plane or combination of those directions as well as boundary conditions. The worst deflection point is produced when the point load is examined at central intersection. But the worst loading point would not necessarily be at the central point.
To find the worst load point, a moving point load is applied to along the vertical and
horizontal beams around mid-spans. Direct stiffness method is used as an analysis tool. Structural model tests are also carried out to confirm the theoretical analysis results.
To find the optimum arrangement of grid system under a given point load, an
optimization technique is applied. In this case, the minimum weight is the objective
function and allowable stress, deflection and other dimension limitations are constraints.
Can Non-Destructive Stress and Microstructure Analysis Support the Fracture Risk Assessment? A Discussion based on the IZFP Experience
Authors: Schneider Eckhardt , Cioclov D.
Published: March 2009

Using computer simulations the influence of different standard deviations of the yield strength, ultimate tensile strength and of Kc values on the probability of the crack growth in an Al-alloy pressure vessel is studied. The state of art of non destructive materials characterization as it is achieved at the IZFP is demonstrated by experimental results of non destructive stress analysis, evaluation of strength data and of materials state characterization. The goals of future developments are clear: in case of components made by Al alloys, the combined use of the ultrasonic and eddy current techniques and in case of steel components, the additional use of micro magnetic techniques have to be enforced. The miniaturization of the sensors and the continuation of the experimental investigation of the correlation between the strength and Kc data on one side and the materials structure as characterized by non destructive tools on the other side are the next steps.
In Situ Micro Raman Spectroscopy for Characterization of Oxide Film Formed on the New Surface and for Measurements of the Stress of Oxide Film Formed on 304L Stainless Steel
Authors: Kai Akira , Takegoshi Masao , Shoji Tetsuo
Published: March 2009

Environmentally assisted cracking (EAC) consists of two distinct events viz., i) crack initiation and ii) crack propagation. On a smooth surface, the EAC initiates by the rupture or by the degradation of the surface film due to the combined action of stress and an electrochemical reaction of the materials with the environment. The mechanical properties of the surface oxide films are also important considerations when determining the susceptibility to EAC.
In this research, Micro Raman Spectroscopy(MRS) was applied for in-situ oxides characterization and for in-situ measurements of the stress in oxide film formed on the surface of 304L stainless steel during the scratching electrode and the slow strain rate test (SSRT), respectively. The passive oxide film growth formed on the bare surface was continuously monitored by MRS as a function of time. For stress measurements, Cr2O3 was focused on and Raman shift at Cr2O3 peak of Raman spectrum was measured continuously. The strain rate was 8.2×10-7 /sec. . In the initial stage of
SSRT, the Raman shift of surface film decreased gradually with strain. At 5% strain, the Raman shift of surface film increased rapidly to around the initial value of Raman shift. It is considered that the surface film was ruptured at this time. At 5% strain, the shift value of Raman peak of Cr2O3 reached to 5cm-1. This value (5cm-1) corresponds to 1.2GPa which value of tensile stress is calculated from reference data.
These characteristics of oxide film will be implemented into the theoretical formulation of EAC and their implication to EAC growth rate will be discussed.
On Microwave Dual Frequency Technique for Evaluation of Surface Cracks
Authors: Saka Masumi , Ju Yang , Uchimura Y. , Miyadu Toru
Published: March 2009

A method to estimate crack closure stress on the crack surface was introduced. The crack closure stress was estimated based on the compliance technique, while crack depth was measured by means of the microwave dual frequency technique. The effect of crack closure stress on detection and evaluation of a closed crack in a carbon steel by using the microwave dual frequency technique was discussed in details.
Association and Phosphorylation of Deoxyhypusine Synthase with CK2
Authors: Kang Kee Ryeon
Published: March 2009

Deoxyhypusine synthase (DHS) catalyzes the first step in the posttranslational synthesis of hypusine in the eukaryotic initiation factor 5A (eIF5A) precursor protein. As such, the phosphorylation of DHS by the protein kinase CK2 was investigated to define the role of DHS in the regulation of eIF5A in cells. The results showed that DHS was phosphorylated by CK2 in vivo as well as in vitro. The endogenous CK2 in HeLa cells and cell lysates was able to phosphorylate DHS and
this modification was enhanced or decreased by the addition of CK2 effectors, such as polylysine, heparin, or poly (Glu, Tyr). A phosphoamino acid analysis of the enzyme revealed that the DHS was mainly phosphorylated into the Thr residue, with the remainder into the Ser residue. Therefore, it would appear that the phosphorylation of DHS was a CK2-dependent cellular event, thereby opening
the path for possible regulation of the interaction with the eIF5A precursor for hypusine synthesis.
Preparation of Nanostructured Metal Ferrite Particles by Sonochemistry
Authors: Kim Eun Hee , Lee Hyo Sook , Shao Hui Ping
Published: March 2009

Nanostructured iron and cobalt ferrite particles were prepared from iron chloride and cobalt chloride, respectively, using the sonochemical method. The particles were compared with those synthesized using the co-precipitation method. The properties of the particles were characterized using various techniques, such as XRD, TEM, VSM and a SQUID magnetometer. The iron ferrite particles had an average particle size of about 15 nm and a magnetization value of 83 emu/g at a magnetic field of 50 kOe, while the particle size of cobalt ferrite was about 5 nm and its magnetization value was 33 emu/g at the same magnetic field.
Visual Feature Extraction under Wavelet Domain for Image Retrieval
Authors: Park Won Bae , Ryu Eun Ju , Song Young Jun , Ahn Jae Hyeong
Published: March 2009

In this paper, we propose a new visual feature extraction method for content-based image retrieval (CBIR) based on wavelet transform which has both spatial-frequency and multi-resolution characteristics. We extract visual features for each frequency band in wavelet transformation and use them for CBIR. The lowest frequency band involves utilizing the spatial information of an original image. We extract 64 feature vectors using fuzzy homogeneity in the wavelet domain, which
considers both the wavelet coefficients and the spatial information of each coefficient. In addition, we extract 3 feature vectors using the energy values of high frequency bands, and store those to the image database. As a query, we retrieve the most similar image from the image database according to the 10 largest homograms (normalized fuzzy homogeneity vectors) and 3 energy values. Simulation results show that the proposed method has good accuracy in image retrieval using 90 texture images.
The Effect of 5-Substitution on the Cytotoxicity of 2-(p-Methoxyphenyl)-1H-Benzimidazoles in Human Cancer Cell Lines
Authors: Kwon Min Jin , Kim Hwan Mook , Kim Dae Duk , Kim Jung Sun
Published: March 2009

A series of 5-substituted 2-(p-methoxyphenyl)-1H-benzimidazoles was synthesized and evaluated for cytotoxicity against 4 human cancer cell lines, HCT 15, PC-3, A549, and ACHN. Except for the 5-chloro analogue, most of the 5-substituted compounds showed significant cytotoxicities in these cell lines. However, the structure activity relationship study revealed that neither the electronic nor the lipophilic parameters of the 5-substituents were related to cytotoxicity. Moreover, none of the analogues showed significant NF к-β inhibition activity implying that cytotoxicity was not related to this mechanism. The 5-methyl analogue was the most potent compound in this series with a GI50 of 0.9 µM in the A549 cell line.
Implementation of a Function-Based Navigation Tool for Facilitating the Analysis of UML Design Document
Authors: Kim Won Jung , Bae Myung Nam , Yang Jae Dong , Yang Hyung Jeong
Published: March 2009

System developers often create design documents using various UML design tools.
Extant tools, however, have a serious drawback. They fail to capture relationships inherently existing among design documents such as sequence, state and class diagrams. This drawback may not only disallow developers to freely navigate the relationships, but also make it difficult to automatically enforce the integrity constraints derived from the relationships. To overcome this, more sophisticated tools for facilitating the analysis of the documents are necessary. These tools
may be used to understand and verify the whole process of the system by defining relationships between documents and providing efficient navigation methods. In this paper, we developed a navigation tool that enables developers to systematically analyze systems by capturing relationships such as duplication, instance, and transition between documents. In contrast with the navigation facilities of other UML design tools, this tool makes it possible to navigate not only design documents but also design elements. In other words, it can systematically capture and verify both
the static structure and the dynamic behavior of the system in more primitive level. To provide such a facility, we addressed the practical issues and formulated a solution for them. The issues that were mainly discussed were the following: 1) definitions of three relationships: duplication, instance, and transition, 2) assignment of relationships to related design elements according to the predefined way, and 3) presentation of a set of functions to navigate them.
Development of an Environmental Sensor for Heavy Metal Ion Detection by Surface Plasmon Resonance Spectroscopy
Authors: Moon Jung Woo , Kang Tae Wook , Oh Seokil , Chah Soon Woo , Choi Kyung Hee , Yi Jong Heop
Published: March 2009

This study demonstrates the measurement and analysis of interfacial reactions of metal ions with organic ligands using the time-resolved SPR instrument. For the substrate, an HDT (1,6-hexanedithiol) ligand was immobilized on a gold thin film using the SAM method. The 50-nm-thick gold thin film was fabricated by thermal evaporation. The target metal ions were Pt ions in an aqueous solution. The adsorption kinetics of metal ions to HDT ligands was obtained.
Radioactivity Analysis of DUPIC Fuel Fabrication Process According to Burn-Up and Cooling Time
Authors: Shin Jin Myeong , Park Jang Jin , Shin Seol Woo , Yang Myung Seung , Lee Ho Hee
Published: March 2009

A radioactivity analysis of OREOX and the sintering steps for the DUPIC fuel fabrication process has been conducted. This study utilized ORIGEN2 code to calculate and analyze the radioactivity of spent fuels for various burn-up and cooling times. The analysis results have shown that the activity reduction of spent fuels after DUPIC fuel fabrication process was 40∼51 % and higher with longer burn-up and cooling times. This study also shows that the distribution of gaseous waste generated from OREOX process is mainly attributed to Kr, Ru and H-3, regardless of burn-up and cooling times. On the other hand, in the off-gas of the sintering process, the radioactivity distribution of Cs is more than 98 %, regardless of burn-up and cooling times.
Biocompatibility of Phema and P(Hema-Co-Sma) Hydrogels
Authors: Park Bo Hyung , Han Young A , Choi Jin Hyun , Lim Jeong Ok
Published: March 2009

To replace a poly(2-hydroxyethyl methacrylate) (PHEMA) sponge, which has limited applications as an implant material, PHEMA and poly(2-hydroxyethyl methacrylate-co-sodium methacrylate) (P(HEMA-co-SMA)) hydrogels with enhanced biocompatibility were prepared based on the copolymerization of 2-hydroxyethyl methacrylate (HEMA) and sodium methacrylate (SMA) at
a high monomer concentration. When the cytotoxicity, cell adhesion, and in vivo tissue reaction of the resulting hydrogels were investigated, the results suggest that hydrogels prepared by the copolymerization of HEMA and SMA at a high monomer concentration have great potential as implant materials with an excellent biocompatibility.
Does Elevated CO2 Affect the Physiology and Growth of Quercus Mongolica under Different Nitrogen Conditions?
Authors: Hyun Kyung Oh , Choung Yeonsook
Published: March 2009

The response of Quercus mongolica, one of the major tree species in Northeast Asia and the most dominant deciduous tree in Korea, was studied in relation to elevated CO2 and the addition of nitrogen to soil in terms of its physiology and growth over two years. Plants were grown from seed at two CO2 conditions (ambient and 700 µL L-1) and with two levels of soil nitrogen supply (1.5 mM and 6.5 mM). Elevated CO2 was found to significantly enhance the photosynthesis rate
and water use efficiency by 2.3-2.7 times and by 1.3-1.8 times, respectively. Over time within a growing season, there was a decreasing trend in the photosynthesis rate. However, the decrease was slower especially in two-year-old seedlings grown in elevated CO2 and high nitrogen conditions, suggesting that their physiological activity lasted relatively longer. Improved photosynthesis and water use efficiency as well as prolonged physiological activity under high CO2 condition resulted in an increase in biomass accumulation. That is, in elevated CO2, total biomass increased by 1.7 and 1.2 times, respectively, for one- and two-year-old seedlings with low nitrogen conditions, and by 1.8 and 2.6 times with high nitrogen conditions. This result indicates that the effect of CO2 on biomass is more marked in high nitrogen conditions. This, therefore, shows that the effect of CO2 is accelerated by the addition of nitrogen. With the increase in total biomass, the number of leaves and
stem diameter increased significantly, and more biomass was allocated in roots, resulting in structural change. Overall, the elevated CO2 markedly stimulated the physiology and growth of Q. mongolica. This demonstrates that Q. mongolica is capable of exploiting an elevated CO2 environment. Therefore, it will remain a dominant species and continue to be a major CO2 sink in the future, even though other resources such as nitrogen can modify the CO2 effect.
Toxicity Screening Tests for Wastewater Treatment Plants – I
Authors: Park Jin Hwa , Yl Yong Woo
Published: March 2009

Toxicity screening tests using the Reserve Electron Transfer (RET) and Electron Transfer (ETr) assays were performed with five wastewater samples amended with trickling filter (TF) or activated sludge (AS) biomass. In the case of untreated samples, Home Life domestic wastewater (HLD/W) showed the lowest inhibition, followed by domestic sewage (DS), hospital wastewater (H/W), East Straus wastewater (ES/W), and Mills wastewater (M/W) from both ETr and RET assays. After 12 hours of treatment at 20°C, DS with AS biomass had the lowest % inhibition from the RET assay, followed by DS with TF, HLD/W with TF, H/W with TF, M/W with TF, and M/W with AS. AS biomass reduced more toxicity from DS than TF biomass whereas acclimated TF biomass reduced significantly more toxicity than AS biomass, indicating the importance of acclimation. M/W was
most toxic and resistant to biodegradation among six wastewater samples. No nitrification occurred with M/W and ES/W. While there was significant nitrification with DS treated by AS biomass, little nitrification by TF biomass occurred even with DS, HLD/W, and H/W. It appears that nitrification is significantly inhibited by M/W and ES/W even when mixed with domestic sewage. It appears that there is a strong relationship between the TIC/TC ratio and % inhibition.
The Effect of Natural Ventilation in a Small Room with an Unvented Gas-Fired Heater
Authors: Yoon Jaeock
Published: March 2009

In small buildings and residences in Korea, unvented or improperly vented combustion appliances are used to heat rooms. These heaters are mostly gas-fired portable equipment used for auxiliary heating. Although their maintenance cost is very low, unvented gas-fired heaters emit air contaminants such as carbon dioxide and carbon monoxide. If there is inadequate ventilation and even a little fresh air with oxygen comes into the appliances, combustion occurs less efficiently and heaters generate more air contaminants. Natural ventilation is the best way to prevent air pollution in small buildings. Outdoor air has a lot of oxygen and can reduce air pollution. The objective and scope of this research is to predict the distribution of indoor air pollution, according to the results of field measurements and CFD (Computational Fluid Dynamics) simulations. In a room of 6.4m×3.1m×2.6m in size, air contaminants (CO2 and CO) and air temperature were measured in two instances--with natural ventilation and without natural ventilation. After comparing the results obtained with computer simulation and field measurements, passive control methods to improve indoor air quality in a room are proposed.
Isolation and Identification of Bacteria from Marine Biofilms
Authors: Lee Yoo Kyung , Kwon Kae Kyoung , Cho Kyeung Hee , Park Jae Hyun , Lee Hong Kum
Published: March 2009

In the marine environment, biofilms cover most of the subtidal and intertidal solid
surfaces. Culturable bacteria forming marine biofilms were isolated on artificial substrate called acrylic coupons. The bacterial isolates were identified through a comparison of 16S rDNA sequences. A total of 115 strains were cultured and identified, 45 of which showed the same sequences with other strains. Therefore, 70 strains were finally identified. The bacterial isolates belonged to a–Proteobacteria (32 isolates), g–Proteobacteria (12 isolates), CFB group bacteria (4 isolates), high GC Gram-positive bacteria (9 isolates), and low GC Gram-positive bacteria (13 isolates). The bacterial isolates may be used as standard bacteria to test new antifouling agent. They may also be utilized as useful bacteria to enhance the settlement of commercial algae and invertebrate larvae for aquaculture.
Effect of a Tetravalent Dopant, Th4+ on the Oxidation of Uranium Dioxide
Authors: Ha Yeong Keong , Kim Jong Goo , Park Yeong Jae , Kim Won Ho
Published: March 2009

The effect of a tetravalent dopant, Th4+, on the oxidation of UO2 was investigated using a thermogravimetry and X-ray diffraction analysis. Th-doped UO2’s with various dopant contents were prepared and their oxidation kinetic curves were obtained from the weight gains during air-oxidation. For the first oxidation step from (U1-yThy)O2 to (U1-yThy)4O9, the oxidation kinetic curves showed the same gradient regardless of the Th content. The inhibition of the oxidation reaction occurred dominantly in the second step, from (U1-yThy)4O9 to (U1-yThy)3O8. At the plateau of the second stage, the calculated O/M values and the X-ray diffraction patterns revealed that the O/M ratio was decreased with an increase of Th content. The relationship between the mean formal charge and the composition showed that the oxidation to (U1-yThy)3O8 proceeds within a certain limit. The lattice parameter of the initial material seems to affect the oxidation rate of the first step. And the oxidation reaction stopped when the average formal charge of the U atoms reached a value of 5.3.
A New Distance Relaying Method with System Load Condition Considered in a Transmission Line
Authors: Moon Hyun Kyung , Hyun Seung Ho , Lee Sung J.
Published: March 2009

This paper presents a novel fault location algorithm for a distance relay of a transmission line. Under the assumption that the source voltages and impedances of both ends are not changed before and after a fault, the fault current and the voltage of the terminal end are estimated including the loading condition. Then, the fault location expression, independent of the fault resistance, is derived using these voltages and currents through a loop analysis, in the manner that the in-feed effect
of the terminal end is eliminated. The suggested algorithm is applied to a typical transmission line to show its effectiveness.
Thermal Analysis on a Satellite Box during Launch Stage by Analytical Solution
Authors: Kim Hui Kyung , Choi Joon Min , Hyun Bum Seok
Published: March 2009

Simple methods are developed to predict temperatures of a satellite box during the launch stage. The box is mounted on the outer surface of a satellite and directly exposed to a space thermal environment for the time period from fairing jettison to separation. These simple methods involve solving a 1st order ordinary differential equation (ODE), simplified from the full governing equation when several assumptions are made. The existence of an analytical solution for the 1st order ODE is determined depending on the treatment of the time-dependent molecular heating term. Even for the case that the analytical solution is not available due to the time dependent term, the 1st order ODE can be solved by relatively simple numerical techniques. The temperature difference between two different approaches (analytical and numerical solutions) is relatively small (less than 1°C along the time line) when they are applied to the STSAT-I launch scenario. The present
methods can be generally used as tools to quickly check whether a satellite box is safe against the space environment during the launch stage for the case that the detailed thermal analysis is not available.
Controlled Release of Growth Factor Using Poly(N-Isopropyl Acrylamide)Copolymer Hydrogels with Different Volume Phase Transition Temperatures
Authors: Han Young A , Lim Jeong Ok , Choi Jin Hyun , Ji Byung Chul
Published: March 2009

The release behavior of the basic fibroblast growth factor (bFGF) from copolymer
hydrogels of N-isopropyl acrylamide (NIPAAm) and sodium methacrylate (SMA) was investigated in relation to the volume phase transition temperatures, which was increased by the incorporation of SMA. In the case of the copolymer hydrogels, a higher volume phase transition temperature was obtained when poly(ethylene glycol) diacrylate (PEGDA) was used as the crosslinking agent,
suggesting that the chain length of the crosslinking agent has a significant affect on the volume phase transition temperature of a P(NIPAAm-co-SMA) hydrogel. The concentration of bFGF released from the hydrogels with PEGDA increased relative to the water content, thereby showing a dependence on the volume phase transition temperature. Hence, the release behavior of bFGF from the PNIPAAm and P(NIPAAm-co-SMA) hydrogels was found to be affected by the volume phase transition temperature, which can be easily controlled by changing the comonomer, monomer feed ratio, and crosslinking agent.
The Development and Performance Analysis of a Ground Control System for an Unmanned Airship
Authors: Kim Hyoun Kyoung , Lee Sang Jong , Kim Tae Sik , Lee Hae Chang
Published: March 2009

A control system and ground pilots who operate the system are necessary to control an unmanned vehicle. This paper describes a Ground Control System(GCS) of the unmanned airship developed at KARI. The system is capable of mission planning, real-time data processing, remote real-time data analysis, and data storage and extraction. We estimate the performance of the system and verify its reliability using real-time simulation software. The software relies on a priority-based
multitasking algorithm. No task has delay time and deadlock with semaphore, all of the ground system works in stable during the test flight.
The Development of a Ka Band Input Filter Assembly for a Satellite Transponder
Authors: Lim Young Hei , Uhm Man Seok , Park Jong Heung
Published: March 2009

This paper presents the development of a Ka band Input Filter Assembly(IFA) with very low insertion loss and a high temperature stability suitable for a communication satellite transponder. The IFA consists of a cross directional test coupler to check the input signal level of the transponder and an input filter to pass the uplink band signals. The test results show good agreement with the simulation and compliant to the requirements with the temperature range from –20 °C to 60 °C. This IFA will be used for the communication satellite in Korea.
Generalized Gravity Theory Constrained by CMBR Observations
Authors: Noh Hyerim
Published: March 2009

We investigate the cosmological perturbations based on the f(R) gravity theory.
Comparing the large angular scale CMBR observation we obtain several important constraints on the inflation model based on the f(R) gravity theory: the ordinary slow-roll assumption during the inflation with the Zel’dovich spectral conditions for the scalar and the tensor-type structures yields R2 gravity as the unique candidate. Also, the considered model predicts the nearly scale-invariant Zel’dovich spectra. We derive the strong constraints on the coupling constants of the R2 term and the
energy scale during the inflation using the COBE-DMR observations. The result shows the gravitational wave contribution is very small. Therefore, future observations of the spectral indices and the gravitational wave contribution to CMBR temperature and polarization anisotropies will subject the current inflation models to a test.
Convergence of the Intuitionistic Fuzzy Spheres
Authors: Kim Mi Hye , Kim Tae Soo
Published: March 2009

In this paper we show that the circularity and the planar functions of an intuitionistic fuzzy sphere converge to one of a crisp sphere as a fuzzy sphere shapes itself more and more like a crisp sphere.
Preparation and Properties of Crosslinked Polyurethane Containing Hydrophilic PEO Component for Biomaterials
Authors: Yoo Hye Jin , Kim Han Do
Published: March 2009

A series of multiblock polyurethanes containing various poly(ethylene oxide) (PEO) contents (0-80 wt%) were prepared from hexamethylene diisocyanate (HDI)/ PEO / poly(tetramethylene oxide) (PTMO)/ polybutadiene diol (PBD)/ 1,4-butanediol (BD) and used as modifying additives (30 wt%) to improve the properties of biomedical grade PelletheneÒ. A hydrophilic PEO component was introduced by the addition of PEO-containing polyurethanes and
dicumyl peroxide (DCP) as the crosslinking agents in a PelletheneÒ matrix. As the PEO content (PEO block length) increased, the hydrogen-bonding fraction of the crosslinked polyurethane also increased, indicating an increase in the phase separation with an increase in the PEO content in the crosslinked polyurethane. Using electron spectroscopy for a chemical analysis, the ratio of ether carbon to alkyl carbon in the crosslinked polyurethane film increased remarkably with an increase, in the PEO content. Meanwhile, the water contact angle of the crosslinked polyurethane film surfaces decreased with increasing PEO content. The water absorption and mechanical properties of the crosslinked polyurethane films increased with increasing and the platelet adhesion on the crosslinked polyurethane film surfaces decreased significantly. Accordingly, these results suggest that the
crosslinked polyurethane containing a hydrophilic PEO component may be more effective for a biomaterial application that is in direct contact with blood.
QSO Identification with BATC Multiband Data
Authors: Sheen Yun Kyeong , Byun Yong Ik
Published: March 2009

We present intermediate-band spectral energy distributions (SED) of QSO candidates in 1 square degree field around Leo Triplet. Leo Triplet consists of three galaxies, NGC3623, 3627, and 3628, which appear to interact with each other. BATC survey data of 15 intermediate-band filters offer excellent opportunity to study low spectral resolution SED for thousands of point sources in the field simultaneously. In order to derive SED of high signal to noise ratio, we have combined hundreds of images for each passband and made photometric measurements for every point sources in the combined images. Two dozens of new QSO candidates are identified based on the shape of derived SED curves. We also investigated SEDs of known QSO candidates in the field, but their SED differs greatly from model predictions made for cataloged redshift. While we plan to carry out
spectroscopic observations for further confirmation, this indicates that QSO identification based on objective prism and X-ray methods should be taken more cautiously.
Effect of Magnetic Field on the Momentum Relaxation Rate of Charge Carriers in a Size-Quantized Wire
Authors: Gasparyan Sh.G.
Published: March 2009

The effect of a longitudinal magnetic field and the dielectric constants mismatch of a
size- quantized wire and surrounding medium on the impurity scattering of charge carriers is considered. The expressions for the momentum relaxation rate are carried out for scattering on charged Coulomb centers located on the wire axis. The dependences of the momentum relaxation rate on the magnetic field induction, dielectric inhomogeneity parameter, and also on the wire radius are obtained.