bluuebunny/crossref_metadata_2025 huggingface dataset:
Dry Sliding Wear of Lu2O3 Sialon Ceramics
Authors: Jones Mark I. , Hirao Kiyoshi , Hyuga Hideki , Yamauchi Yukihiko
Published: March 2009

The effects of microstructure and composition on the wear properties of Lu sialon ceramics have been studied under dry sliding conditions through block-on-ring wear tests. Microstructural and compositional effects on wear behaviour were studied by producing both equiaxed and elongated α sialons through the incorporation of additional oxides to promote extended liquid formation and grain growth, and by producing α / β composite materials with elongated β grains. The wear response of the materials is discussed in terms of the dominant wear mechanism under different experimental conditions. Under higher loads, where fracture dominates, materials with improved mechanical properties show better wear resistance and both the composite materials and the elongated α sialons showed lower wear rates than the equiaxed materials due to the elongated grain microstructures. Under low normal loads, fracture does not occur and the dominant wear mechanism is thought to be tribochemically assisted wear. Under these conditions, the equiaxed materials had better wear resistance than the composites, and the Lu-α sialon showed an order of magnitude lower wear rate than an equivalent Y-α sialon, thought to be due to better oxidation resistance and improved refractory nature afforded through the use of the smaller radius cation. The elongated Lu-α sialons under these low load conditions showed wear resistance that was to some extent dependent on the composition of the additional liquid phase, with high SiO2 contents leading to higher wear rates.
Increasing the Effectiveness of Aluminium Phosphate Binders
Authors: Mulcahy C.L. , Clegg W.J.
Published: March 2009

A method is presented for more than doubling the volume yield from an AlPO4 precursor,
aluminium chlorophosphate ethanolate, from approximately 20% to 50% by replacing the ethanol
ligands with water. It is shown that this increases the volume yield from about 20% to 50%. The
precursor is used to make an Al2O3 powder bonded with an amorphous AlPO4 with a Young modulus
of 80 GPa and a strength of 60 MPa.
Preparation of Ce-ZrO2 Based Composites and Effect of Addition of 3Y-ZrO2 on Their Microstructures
Authors: Nakahira Atsushi , Ohta Mitsuhiko , Murakami T. , Kudo T.
Published: March 2009

12 mol%CeO2 based composites were fabricated by a pressureless sintering technique and post-HIP
treatments. The mixture of 12CeO2-ZrO2/3Y2O3-ZrO2 (= 80 wt%/20 wt%) powders from various methods were
prepared by a ball milling technique and consequently sintered at 1400 in air atmosphere and post-HIP treatment
at 1350. The 12Ce-ZrO2/Y-ZrO2 composites sintered from mixture of 12CeO2-ZrO2 powder and 3Y2O3-ZrO2
powders possessed the high strength over 1300 MPa and also high fracture toughness over 11 MPam1/2. Furthermore,
the significant inhibition of the ZrO2 phase transformation of tetragonal to monoclinic phase under an aqueous
hydrothermal condition at 150 was obtained for these 12Ce-ZrO2/Y-ZrO2 composites prepared from this method.
Microstructural observation was in detail performed by TEM and EDS.
Thermal and Electrical Conductivities of Porous Carbon-Coated Ceramic Fiber Composites
Authors: Lee Jae Chun , Yu Jun Suh , Sung Jae Hoon , Park Sung , Choi Sung Chul
Published: March 2009

Porous ceramic fiber composites were coated with pyrolytic carbon by the decomposition of infiltrated phenolic resin in a nitrogen atmosphere at 800. The amount of carbon coating was varied to tailor the electrical conductivity of the carbon-coated composites. The electrical and thermal conductivity of the composites were measured at room temperature using a two-point method and a hot-wire one, respectively. Up to 30 wt% pyrolytic carbon, the electrical conductivity σ shows linearly increasing tendency and is fitted by the effective conductivity according to the parallel rule of a mixture σeff = ΣΧi ·σi with an effective conductivity of pyrolytic carbon σc= 0.42 S/cm. The thermal conductivity of the coated composites is in the range 0.05-0.08 W/mK and increases with carbon content.
Synthesis of Monodispersed Inorganic-Organic Hybrid Particles from Phenyltriethoxysilane
Authors: Shimoike K. , Matsuda Atsunori , Muto Hiroyuki , Sakai Mototsugu
Published: March 2009

Preparation of monodispersed inorganic-organic hybrid particles has become one of the
most attractive research topics in recent years. In this study, phenylsilsesquioxane (PhSiO3/2) particles
were synthesized from phenyltriethoxysilane (PhSi(OEt)3), ethanol (EtOH), hydrochloric acid for
hydrolysis and ammonia water for polycondensation by the sol-gel method. Spherical PhSiO3/2
particles were obtainable by varying the mole ratios of EtOH, H2O, HCl and NH3, to PhSi(OEt)3. The
particle size was changed from 0.1 to 5.0 .m with the mole ratio. Under the optimum conditions,
monodispersed particles with 1.50 .m in diameter and 0.05 of normalized standard deviation were
successfully prepared.
Preparation of Bimodal Porous Apatite Ceramics through Slip Casting Using Fine Hydroxyapatite Powders
Authors: Zhang Yin , Yokogawa Yoshiyuki , Kameyama Tetsuya
Published: March 2009

A bimodal porous hydroxyapatite (HAp) body with high flexural strength was prepared through slip casting. HAp fine powder used in this study was synthesized by wet milling, drying and heating of a mixture of calcium hydrogen phosphate di-hydrate and calcium carbonate. The synthesized HAp powder was 0.320.05 μm in size and 38.10.8m2/g in specific surface area. The slip was prepared by adding deflocculant and foaming reagent. The optimum value for the minimum viscosity in the present HAp slip with respect to its solid loading and the optimum amount of the deflocculant were studied. The total porosity of the specimens obtained from a slip of 48 wt% HAp solid loading is in the range of 49 – 61vol %, and the resultant porous HAp sintered body had large spherical pores of 300 -m with interconnecting rectangular voids. Many small pores in the size range of 2-3 -m or below were observed in the specimen obtained by heating at 1100, and 1200 . The flexural strength of the bimodal porous HAp ceramics sintered at 1200 C showed a large value of 17.6 MPa, with a porosity of 60.5vol.
Characteristics of Wall and Floor Tiles Using Waste Glass
Authors: Kim Young Kil , Jung Yeon Gil , Song Jun Baek , Shin Min Chul , Lee Hee Soo
Published: March 2009

Wall and floor tiles were fabricated by a dry pressing method using waste glass and clay.
The properties of the tiles such as absorption, bulk density, porosity, compressive strength, and
abrasion loss are investigated with the firing temperature and glass content. The properties are
improved with increasing both the firing temperature and glass content. These properties, except the
compressive strength, tend to be saturated from the glass contents of 70 wt % in the case of 1050 .
The compressive strength shows the maximum values at the glass contents of 70 wt% and then which
are decreased with increasing the glass contents. The optimal properties obtained in the tiles are the
water absorption of about 0.9 %, the bulk density of about 2.3 g/cm3, the apparent porosity of about
2.1 %, the compressive strength of about 210 MPa, and the abrasion loss of about 0.022 g, when the
composition containing the glass of 70 wt% is fired at 1050. These results are better than the
properties of commercial clay tiles, due to easy melting and densification of glassy phase in the tiles.
Correlation of Physical Properties of Inorganic Carrier and Microbial Survival Rate
Authors: Lim Hyung Mi , Lee Seung Ho , Park Jun Bo , Kwon Jin A , Yu Yeon Su
Published: March 2009

Physical properties of various inorganic materials have been measured in terms of pore size
distribution and porosity, BET surface area by nitrogen adsorption, pH, ion conductivity, and
concentration of ions after elution test. The microbial survival rate and their stability have been
monitored in every 10 days during 120 days by dilution plating method. The correlations between
physical property of the inorganic carrier and microbial survival rate have been examined for the
better preparation of microbial fertilizer. Average size of pore, and concentration of soluble ions were
unequivocal factors affecting on microbial survival rate but BET surface area, average porosity, and
ion conductivity revealed the equivocal correlation with microbial survival rate. Higher concentration
of soluble ions gives lower survival rate and inorganic carriers with high microbial survival rate
seemed to have preferred range of pore size.
The Intelligent Catalyst: Pd-Perovskite Having the Self-Regenerative Function in a Wide Temperature Range
Authors: Tanaka Hirohisa , Tan Isao , Uenishi Mari , Taniguchi Masashi , Nishihata Y. , Mizuki Jun'ichiro
Published: March 2009

An innovative Pd-perovskite “Intelligent Catalyst”, which exhibits a greatly improved durability owing to the self-regeneration function of Pd nanoparticles, has been developed. The Pd-perovskite catalyst was prepared by the alkoxide method, and X-ray absorption fine structure (XAFS) measurements were carried out in SPring-8 using the 8-GeV synchrotron radiation. Pd occupied the B-site (6-fold coordination) of the perovskite lattice in the oxidative atmosphere, and segregated out to form metallic nanoparticles in the reductive atmosphere. The catalyst retained a predominantly perovskite structure throughout a redox cycle of the exhaust-gas, while the local structure around Pd could be changed in a completely reversible manner. The agglomeration and growth of the metal particles is suppressed as a result of the Pd movement between inside and outside the perovskite lattice. This function enables an automotive catalyst to regenerate itself into an active state in fluctuation typically encountered in the exhaust gas from the gasoline engine. And it is revealed, by in-situ and ex-situ XAFS analyses, that the self-regenerative function of Pd occurred in a wide temperature range from very low to high one. The intelligent catalyst is one solution for precious metals supply and demand problem, and is expected to become the global standard of the catalyst technology.
High Damping Performance of Hydrogenated Bulk Metallic Glasses
Authors: Mizubayashi H. , Yamagishi K. , Tanimoto H.
Published: March 2009

Hydrogenated Zr-Cu-base metallic glasses (MGs) are the potential high-damping and
high-strength materials. On the other hand, the knowledge on the material parameters which govern
the peak temperature, Tp, and the peak height, Q-1
p, of the hydrogen internal friction peak (HIFP)
remains poor. In order to pursue this issue, the hydrogen concentration dependence of Tp and Q-1
p in
the Zr-Cu-base MGs were investigated in the point of view of the hydrogen induced structural
relaxation (HISR). It is found that the Tp vs. CH data and the Q-1
p vs. CH data are well fitted by the
relationships of Tp = Tp exp(-CH/τH) +Tp,0 and Qp
-1 ∝ ln(CH/τH), respectively, for various
Zr-Cu-base MGs including bulk MGs, Zr55Cu30Al10Ni5 and Zr60Cu30Al10. That is, the observed
relationship between Tp and CH is mainly governed by HISR. It is suggested that Tp,0 in Zr-Cu-base
MGs is the highest among various MGs resulting in the highest Tp in Zr-Cu-base MGs. In other
words, the control of Tp,0 is the key issue to find the high-Tp MGs.
Cathodoluminescence of Diffusion Layer Synthesized by Coupling of β-Ga2O3 and ZnO
Authors: Suzuki Kenichi , Kuroki Yuichiro , Okamoto Tomoichiro , Takata Masasuke
Published: March 2009

Beta gallium oxide (β-Ga2O3) ceramics was coupled and reacted with zinc oxide (ZnO) ceramics
at 1200oC for 24 h. Energy dispersive X-ray spectroscopy (EDS) analysis revealed the existence of
diffusion layer near the interface between β-Ga2O3 and ZnO. Furthermore, the layer showed
monochromatic and intense cathodoluminescence (CL) at 3.5 eV. On the other hand, very weak
emissions were observed from the out of the layer. The compound in the layer is considered to be an
attractive material for ultraviolet optoelectronics.
Photoinduced Nanodots in Bi2Sr2CaCu2O8+d
Authors: Osada Minoru , Kakihana Masato , Yasuoka H. , Käll M. , Börjesson L.
Published: March 2009

We report a fabrication of high-density nanodots by photodoping in overdoped Bi2Sr2CaCu2O8+d
thin film (Tc = 80 K). A scanning near-field optical microscope probe is used to locally excite
carrier, and photodoped region is associated with lower Tc phase (Tc = 75 K) via overdoping.
Nanoscale characterizations with optical reflectivity reveal that nanodots (30-nm diameter) are
regularly distributed in 50-nm step. The resultant films with photoinduced nanodots enhance Jc, a
situation being similar to strong pinning effects observed in films modified by either ion irradiation
or sputtered nanoparticles. These results suggest that photoinduced nanodots with lower Tc act as
effective pinning centers.
Characterization of Dielectric Properties of Alkoxy-Derived (Y,Yb)MnO3 Ferroelectrics /HfO2 Stacking Layers
Authors: Suzuki Kazuyuki , Guo Yi Ping , Nishizawa Kaori , Miki Takeshi , Kato Kazumi
Published: March 2009

The Y0.5Yb0.5MnO3 ferroelectrics/HfO2 stacking layer was constructed on Si(100) substrate through
the chemical solution deposition. The HfO2 insulating layer crystallized on Si(100) substrates
consisted of uniform grains and had smooth surface. The Y0.5Yb0.5MnO3 film prepared on the HfO2
insulator layer had preferred orientation along c-axis. The Y0.5Yb0.5MnO3 film consisted of uniform
grains and had smooth surface. The clockwise C-V hysteresis induced by ferroelectric polarization
switching was observed in the MFIS structure. The memory window of the MFIS structure was
about 2 V and the retention time was over 105 s.
Monitoring of Bone Temperature during Osseous Preparation for Orthodontic Micro-Screw Implants: Effect of Motor Speed and Ressure
Authors: Nam Okhyun , Yu Wonjae , Choi Man Yong , Kyung Hee Moon
Published: March 2009

The temperature at the surface of the bony recipient site during drilling for
orthodontic micro-implant placement was monitored using infrared thermography. The primary
objective was to identify proper drilling conditions to allow efficient drilling without raising the
bone temperature above the threshold temperature of 44oC to 47oC. Bovine ribs were selected to
provide cortical bone of a similar quality to the human mandible. Four drilling conditions
combining 2 motor speeds (600 and 1200 rpm) and 2 pressure loads (500 g and 1000 g) were
established based on clinical practice. Much care was taken to duplicate an oral environment,
although no irrigation was used to allow the infrared radiation to transmit without being hindered by
cooling water. Thermal images were recorded using a Thermovision 900 system (Amega,
Danderryd, Sweden). The results showed that the temperature rise relys significantly on the drilling
speed and pressure. When both the drilling speed and the pressure were low, the cortical bone could
not be cut. However, increasing either the speed or the pressure resulted in a temperature increase.
Drill speed of 600 rpm at the pressure load 1000g produced more or less the same temperature, 40-
45 o C, as when the drill speed was increased to 1200 rpm while keeping the load at 500g. Yet, a
temperature as high as 62.4 o C was recorded when combining the high motor speed and high
pressure. Most of the temperature rise took place during the initial 5-10 seconds of drilling,
indicating that intermittent irrigation at an interval of 5 seconds or less would be of particular
importance to minimize possible thermal trauma.
Influence of Shearing Amount on Detecting Crack-Shaped Internal Defect by Shearography
Authors: Kang Ki Soo , Kim Koung Suk , Jung Hyun Chul , Jang Heo Sub
Published: March 2009

Shearography, a type of speckle interferometry, is a powerful tool for nondestructive
testing (NDT) because it is insensitive to environmental vibration disturbance and easy to detect strain
concentration in an internal defect with noncontact and whole field. The shearing amount in
Shearography has influence on determining defect size and source location. Thus the shearing amount
must be optimally adjusted to get accurate evaluation. This paper investigates the defect size and
source location according to the change of shearing amount in artificial slender defects along
longitudinal direction of pipeline. Based on the investigation, a new technique is proposed for the
quantitative determination of defect size and source location.
Non-Invasive Analysis of Trabecular Microstructural and Biomechanical Properties in Obese OLETF Rats
Authors: Baek Myong Hyun , Chung Yoon Sok , Won Ye Yeon , Cui Wen Quan , Kim Hak Kyun , Chung Choon Hee , Yoo Seung Hyun , Kim Kwang Kyun
Published: March 2009

Investigation of the bone mineral density (BMD), microstructural and mechanical properties in the Otsuka Long Evans Tokushima Fatty (OLETF) and Otsuka Long Evans Tokushima Fatty (LETO) rats were performed. The BMD and microstructural analyses were carried out using PIXI-mus and non-invasive highresolution micro-computed tomography (micro-CT) system. The mechanical properties analyses were determined by finite element analysis based on micro-images. The BMD was significantly larger in LETO rat than in OLETF rat. The microstructural and mechanical properties were deteriorated and decreased in OLETF rat. The results showed that bone strength is decreased in OLETF in spite of high body weight.
Ultrasonic Characterization of Thermal Distribution in Vicinity for a Cylindrical Thermal Lesion in a Biological Tissue
Authors: Jeong Mok Kun , Choi Min Joo , Kwon Sung Jae , Bae Moo Ho , Paeng Dong Guk , Zeqiri Bajarm , Wright Louise , Coleman Andrew
Published: March 2009

The study considers an ultrasonic characterization on the thermal distribution in vicinity for a cylindrical thermal lesion formed in a biological tissue. The cylindrical heat source is made of a standard nichrome wire with the diameter of 1 mm. The wire was inserted inside a pork muscle housed in a cuboidal container made of perspex. The heat is conducted radially outwards from the wire to the surrounding tissue. Thermal distribution near the heated wire was predicted by numerically solving a bioheat transfer function using FemLab (Comsol, Inc.). As the wire temperature was raised from the environmental temperature 20 °C to more than 80 °C in steps of 5 °C, ultrasonic B-scan images were acquired at each temperature. We assessed the feasibility of detecting the lesion boundary using changes in echogenicity, changes in centroid frequency due to attenuation, tissue moving characteristics resulting from changes in the speed of sound, and elastograms. These observations will be of use in improving ultrasonic monitoring and guiding in HIFU surgery and thermo-therapeutic process in general.
NDE of Decayed Wood with Ultrasonic CT
Authors: Kim Kwang Mo , Lee Jun Jae
Published: March 2009

Recently, a new ultrasonic CT system has been developed as the NDE method suitable for
wood. In this system, several characteristics related to the ultrasound traveling in the woods such as
the anisotropy of woods, existence of immature woods and ultrasound diffraction in the woods are
considered during image composition process.
In this study, we inspected the system that had been newly developed for the decayed wood
specimen. We performed the ultrasound measurements to reconstruct the CT image. And then, we
verified the distributions of each characteristic in the section by measuring the moisture content,
specific gravity and compressive strength after cutting the measured specimen by small specimen
again. The acquired results are compared with the CT image acquired in the same section. As a result,
it is determined that it is possible to detect the locations and sizes of decayed parts in the wood by
using the developed ultrasound CT system. In particular, the results show that the initial decays that
the weight loss rate is less than 10% and the strength loss rate is less than 30% are also detectable.
A Real-Time Automatic Inspection System for Pattavia Pineapples
Authors: Kaewapichai Watcharin , Kaewtrakulpong Pakorn , Prateepasen Asa
Published: March 2009

This paper presents a machine vision method to inspect the maturity of pineapples that ripe naturally. Unlike previous methods, the proposed technique can be categorized as a real-time non destructive testing (Real-Time NDT) approach. It consists of two phases, learning and recognition phases. In the learning phase, the system constructs a library of reference pineappleskin- color models. In the recognition phase, the same process is performed to build a pineappleskin- color model of the testing subject. The model is then compared with each of the reference in the library by a method called region-segmented histogram intersection. The subject is then labeled with the grade of the best match. The system achieved a high performance and speed (3 frames/sec.) in our experiment. The system also includes weighing machine on belt transmission for weight prediction.
Internal Quality Estimation of Watermelon by Multiple Acoustic Signal Sensing
Authors: Lee Kang Jin , Choi Wank Yu , Kim Gi Young , Kang Suk Won , Noh Sang Ha
Published: March 2009

Watermelons are usually sorted by theirs weight and internal quality. Some automated watermelon weight sorters have been developed and operated in watermelon production areas. However, inspection of internal quality of watermelon is still performed by manually. Principal method of identifying internal defect of watermelon is analyzing the percussion sound of watermelon by human experts. Development of non-destructive evaluation technique for internal quality of watermelon is required to reduce human decision errors. The objective of this study was to develop a non-destructive sorting system which can detect internal defect of watermelons. The internal defect evaluation system has a constant-force hitting hammer to generate the acoustic sound, a multi-point sound signal acquiring system, a noise removal circuit, and a signal processing and quality evaluation program. An internal quality prediction model by PLSR (Partial Least Square Regression) was developed by analyzing the percussion sound of watermelons. Using the developed model, the prediction result shows that the overall prediction accuracy was 90.1%, and severely defected watermelons were identified perfectly.
Image Processing Based Automatic Inspection for Assembly Line of Automobiles
Authors: Chung Yun Koo , Kim Ki Hong
Published: March 2009

Many visual automatic inspection methods are used in the assembly line of vehicles for
improving quality and reducing a production cost. In order to resolve uneasy inspection problems,
new useful methods and devices have been developed. A real factory environment has very poor
optical conditions. Illuminations are affected by the sun lights passing through the windows of the
factories. The floor is continuously vibrating, which could affect the posture of installed cameras and
illumination devices. This paper describes how to overcome these problems and suggests the
automatic inspection system applicable to the automobile assembly line. It introduces two feature
extraction methods and algorithms to detect the opened car in the automobile assembly line. The
methods for extracting these features are discussed in this paper with the experimental results.
Effect of Anisotropy on The Thermoelectric Properties of Bi1Sb3Te6 Added with Au Alloys Prepared by Mechanical Alloying Process
Authors: Min Wang Kee , Lee Chang Ho , Park Yong Ho , Park Ik Min
Published: March 2009

An effect of anisotropy on the thermoelectric properties of Bi1Sb3Te6 added with Au alloys prepared by a mechanical alloying process has been studied. The conduction properties including electrical conductivity and thermal conductivity were increased with Au content. The electrical conductivity and the power factor of the perpendicular direction to the pressing direction were larger than those of the parallel direction to the pressing direction. The intensity of (1 1 0) perpendicular plane was larger than that of the parallel plane. It was suggested that the increase of intensity of the (1 1 0) plane would contribute to improve the thermoelectric performance. Although the power factor and thermal conductivity revealed the anisotropic behavior with direction, the Z value showed almost the equal value regardless of direction. From these results, it appeared that the Z value of the Bi1Sb3Te6 added with Au alloy prepared by powder metallurgy process was almost isotropic.
Structural Health Monitoring Based on Electrical Impedance of a Carbon Nanotube Neuron
Authors: Kang In Pil , Lee Jong Won , Choi Gyeong Rak , Jung Joo Yung , Hwang Sung Ho , Choi Yeon Sun , Yoon Kwang Joon , Schulz Mark J.
Published: March 2009

This paper introduces a new sensor design based on a carbon nanotube structural neuron for structural health monitoring applications. The carbon nanotube neuron is a thin and narrow polymer film sensor that is bonded or deposited onto a structure. The electrochemical impedance (resistance and capacitance) of the neuron changes due to deterioration of the structure where the neuron is located. A network of the long carbon nanotube neurons can form a structural neural system to provide large area coverage and an assurance of the operational health of a structure without the need for actuators and complex wave propagation analyses that are used with other SHM methods. The neural system can also reduce the cost of health monitoring by using biomimetic signal processing to minimize the number of channels of data acquisition needed to detect damage. The carbon nanotube neuron is lightweight and easily applied to the structural surface, and there is no stress concentration, no piezoelectrics, no amplifier, and no storage of high frequency waveforms. The carbon nanotube neuron is expected to find applications in detecting damage and corrosion in large complex structures including composite and metallic aircraft and rotorcraft, bridges, and almost any type of structure with almost no penalty to the structure.
Failure Analysis and Evaluation of Strength Properties for Brazed Joints
Authors: Kang Ki Weon , Lee B.J. , Jhang Kyung Young , Kim Jung Kyu
Published: March 2009

This study was aimed at identifying failure mechanism and strength of brazed copper pipe
used in household air conditioner. For these ends, the brazed joints with various brazing length were
manufactured according to manufacturer’s recommended methods. The 3-dimensional X-ray
technique was used to identify internal flaws and their failure mechanism in brazed joints. And,
strength of brazed joint was evaluated by static tests. To evaluate the effect of heat on the brazed joints,
the micro-Vickers hardness is measured. Also, bursting tests were performed for burst pressure of
brazed joints by using of self-designed internal pressure bursting tester.
The Effect of Parameter Distribution Pattern on Frequency Response Localization in Nearly Periodic Systems
Authors: Shin Sang Ha , Yoo Hong Hee
Published: March 2009

In a mechanical system that has periodically repeated subcomponents, premature failures or
malfunctions often occur. Due to slight irregularities of parameters of periodic systems, maximal
frequency responses of a few subcomponents become often significantly larger than those of other
subcomponents. These phenomena, called frequency response localization, need to be comprehended
for reliable designs of the periodic systems. In the present study, the effects of parameter distribution
patterns on the frequency response localization are investigated. Probabilistic results of the frequency
response localization characteristics with two distinct parameter distribution patterns are exhibited.
A Diagnostic Technique for the Inspection of Pipes in MOCVD System
Authors: Yun Ju Young , Shin Yong Hyeon , Chung Kwang Hwa
Published: March 2009

In examining particulate deposits in the pipes within a chemical vapor deposition (CVD) system, vibration diagnostics is compared and studied against ultrasonic diagnostics. The latter method involves pulsing the outer wall of pipes with an ultrasonic sensor and analyzing the resulting echo to observe particulate deposits inside pipes. Vibration diagnostics examines the existence of particulate deposits by analyzing the difference in the frequencies generated when a vibrator is adhered to the outer wall of pipes. With ultrasonic diagnostics, good test results were obtained only when particulate deposits were attached to the inner wall of the pipes. After some time, however, particulate deposits were not detected properly, as the ultrasonic wave failed to cross the fine gaps created between the inner wall of the pipe and the deposits. In conclusion, the vibration diagnostics is being expected as the effective method in monitoring the particulate deposits inside pipes in the CVD system where the desired behavior is reduced frequency along with the the particulate deposits in comparison to the case where the pipe is clean.
Ultrasonic Measurement of Elastic Properties of Nanostructured Alumina
Authors: Kim Noh Yu , Kim Hee Joon , Oh Se Woong , Hozumi N. , Lee Cheol Kyou , Hong Min Sung
Published: March 2009

In this paper, elastic moduli of nanostructured alumina are evaluated by simultaneous
measurement of longitudinal and shear wave velocities using mode-converted ultrasound in scanning
acoustic microscope (SAM). Mode-converted longitudinal and shear waves inside alumina sample
are captured to calculate acoustic wave velocities and determine elastic constants such as Young’s
modulus and Bulk modulus. Al2O3 nanostructured alumina samples are formed by compacting
micro-sized Al2O3 powder with nano-sized Al2O3 powder from 10wt% to 50wt%, and tested by SAM
to investigate elastic moduli. A correlation is found from experiment that the more percentage of
nano-particles are added, the higher elastic moduli are obtained. It is also shown that the
mode-converted ultrasound is sensitive enough to characterize mechanical modulus of nanostructured
alumina quantitatively.
A Study on the Measurement System Using an Ultrasonic Sensor in Electron Beam Welding
Authors: Hong Min Sung , Kim Noh Yu , Kim Jong Min
Published: March 2009

Electron beam welding (EBW) has an important role in industrial applications such as semi-conductor and LCD manufactures because of its high performance and accuracy. Since the operation is done in a vacuum room, it is very difficult to test the weldability as well as the correct welding area of the specimen. In this study, a measurement system of the EBW was developed based on the 3-axis LVDT controlled table. In addition, the algorithm to tracking the welding line has been developed. The weldability of the aluminum specimen was tested by a newly developed measurement system with ultrasonic C-scan inspection.
Fatigue Crack Growth Monitoring by Optical Fiber Sensors in Smart Composite Patch Repairs
Authors: Seo Dae Cheol , Kwon Il Bum , Lee Jung Ju
Published: March 2009

The fiber optic smart structures allow engineers to add nerve systems to their designs,
giving structures capabilities that would be very difficult to achieve by other means, including
continuous assessment of damage processes. In this study, we evaluated the potentiality of the
application of the optical fiber sensors to the monitoring of the fatigue crack growth behavior of
composite patch repaired structures. The composite patch with embedded optical fiber sensors can be
considered as a smart patch which has both repairing and monitoring functions. We used recently
developed Transmission-type Extrinsic Fabry-Perot Interferometric (TEFPI) optical fiber sensors for
the monitoring of fatigue crack growth behavior of cracked thick aluminum plate repaired with
bonded composite patch. The sensing principle and the senor construction of the optical fiber sensor
are presented. The experimental results show that it is possible to monitor the fatigue crack growth
behavior of structures repaired with composite patch using the optical fiber sensor
Experimental Study of Sliding Load According to Changes of Axial Bolt Clamping Force of H-Beam Affected by Pure Bending
Authors: Kim Chun Ho
Published: March 2009

Despite being an important element to connect the major building materials in a steel
bridge, bolt joints have not been sufficiently studied in terms of each defect generated in them.
Among defects in bolt joints of steel bridges currently in public use, the most frequently occurring
problem is the insufficient axial bolt clamping force. To measure sliding load caused by change in
axial bolt clamping force, a test sample of H-beam applied with pure bending was created and static
tests were administered. Based on the axial bolt clamping force of the test sample where the
designed axial bolt clamping force is 100%, tests were carried out with different axial bolt clamping
forces of 75%, 50% and 25%. Then, the sliding load caused by change in the axial bolt clamping
force was analyzed.
A Micromechanical Model for Ductile Fracture of API X65
Authors: Oh Chang Kyun , Kim Yun Jae , Baek Jong Hyun , Kim Young Pyo , Kim Woo Sik
Published: March 2009

This paper presents a micro-mechanical model of ductile fracture for the API X65 steel, using the Gurson-Tvergaard-Needleman (GTN) model. Experimental tests and FE damage simulations using the GTN model are performed for smooth and notched tensile bars with three different notch radii, from which micromechanical parameters in the GTN model are calibrated. The calibrated micro-mechanical model is applied to quantify pre-strain effects on plastic deformation and fracture of the API X65 steel. Good agreements of the FE damage results with experimental data suggest confidence in the use of the proposed micro-mechanical model to simulate ductile failure of pipelines made of API X65 steels.
Thermo-Mechanical Fatigue of the Nickel Base Superalloy IN738LC for Gas Turbine Blades
Authors: Hyun Jung Seob , Song Gee Wook , Lee Young Shin
Published: March 2009

A more accurate life prediction for gas turbine blade takes into account the material behavior under the complex thermo-mechanical fatigue (TMF) cycles normally encountered in turbine operation. An experimental program has been carried out to address the thermo-mechanical fatigue life of the IN738LC nickel-base superalloy. High temperature out-of-phase and in-phase TMF experiments in strain control were performed on superalloy materials. Temperature interval of 450-850 was applied to thermo-mechanical fatigue tests. The stress-strain response and the life cycle of the material were measured during the test. The mechanisms of TMF damage is discussed based on the microstructural evolution during TMF. The plastic strain energy based life pediction models were applied to the stress-strain history effect on the thermo-mechanical fatigue lives.
Semi-Parametric Learning for Classification of Pitting Corrosion Detected by Acoustic Emission
Authors: Prateepasen Asa , Kaewtrakulpong Pakorn , Jirarungsatean Chalermkiat
Published: March 2009

This paper presents a Non-Destructive Testing (NDT) technique, Acoustic Emission
(AE) to classify pitting corrosion severity in austenitic stainless steel 304 (SS304). The corrosion
severity is graded roughly into five levels based on the depth of corrosion. A number of timedomain
AE parameters were extracted and used as features in our classification methods. In this
work, we present practical classification techniques based on Bayesian Statistical Decision Theory,
namely Maximum A Posteriori (MAP) and Maximum Likelihood (ML) classifiers. Mixture of
Gaussian distributions is used as the class-conditional probability density function for the
classifiers. The mixture model has several appealing attributes such as the ability to model any
probability density function (pdf) with any precision and the efficiency of parameter-estimation
algorithm. However, the model still suffers from model-order-selection and initialization problems
which greatly limit its applications. In this work, we introduced a semi-parametric scheme for
learning the mixture model which can solve the mentioned difficulties. The method was compared
with conventional Feed-Forward Neural Network (FFNN) and Probabilistic Neural Network (PNN)
to evaluate its performance. We found that our proposed methods gave much lower classificationerror
rate and also far smaller variance of the classifiers.
Experimental Study on the Fatigue Strength of the Bogie Frame for Tilting Railway Vehicles
Authors: Kim Nam Po , Kim Jung Seok , Seo Sung Il , Park Tae Won
Published: March 2009

This paper shows the experimental study to evaluate the fatigue strength of a bogie frame
for Korean tilting train. The various load cases were established based on the international standard
(UIC615-4) and the special tilting load case, which is unique in the tilting train, was derived by
dynamic analysis and logical assumption of operation under worst tilting condition. The experimental
study was conducted by means of two ways, both static and fatigue loading test. Through the static
load test, the safety against fatigue was assessed using Goodman diagram of the material used. The
fatigue load test was carried out up to 1x107cycles. The fatigue strength was assessed by fatigue crack
inspection by means of NDT test at the stage of 6x106cycles and 1x107cycles.
Evaluation of Tensile Properties and Bending-Induced Residual Stress of Slender Copper Pipe
Authors: Kim Sang Young , Kim Hyung Ick , Seok Chang Sung , Lee Jae Kwan , Mo Jin Yong , Park Deug Yong
Published: March 2009

Used pipes in various mechanisms and structures are produced from raw material by
extruding and drawing. The properties such as yield strength, tensile strength, and elongation of a
pipe produced by these methods are different from the properties of their raw material. But
designers use the properties of the raw material because the actual properties of the pipes are
difficult to obtain from testing. Also, the pipe is used after it has been bent in a complex manner and
cut to fit it to mechanisms and structures. The bending process, especially, induces deformation of
the pipe’s section and residual stress, which are involved in the plastic deformation of the bended
pipes. This residual stress affects the pipe’s properties, including its fatigue life. Therefore, it is very
important to understand the residual stress of a material. But, the distribution of residual stress of a
U-shaped pipe, which is examined in this study, is very complicated and cannot be measured
exactly.
Effect of Biaxial Static Loads on Fatigue Crack Propagation Behavior under Cyclic Tensile and Torsional Loading
Authors: Huh Yong Hak , Park Philip , Kim Dong Jin , Park Jun Hyub
Published: March 2009

Fatigue crack propagation behavior under cyclic tensile or torsional loading with biaxial static
loads has been investigated. Two different biaxial loading systems, i.e. cyclic tensile loading with static
torsional load and cyclic torsional loading with static tensile load, were employed to thin-walled tubular
specimens. The crack propagation was measured by two crack gages mounted near the notch and crack
opening level was measured by unloading compliance method. The directions of the fatigue crack
propagated under respective biaxial loading conditions were examined and the growth rates were
evaluated by using several cyclic parameters, including equivalent stress intensity factor range, Keff,
crack tip opening displacement range, CTD, minimum strain energy density factor range, Smin.
Furthermore, the growth rates were evaluated by effective cyclic parameters considering crack closure. It
was found that the biaxial static stress superimposed on the cyclic tensile or torsional loading tests has no
influence on the propagation directions of the cracks. Furthermore, it was shown that the fatigue crack
growth rates under biaixial faigue loading were well expressed by using the cyclic fatigue parameters,
Keq,eff, CTDeff, Smin,eff considering crack closure effect.
The Impact Collapse Characteristics of Al/CFRP Members for Light-Weight
Authors: Yang In Young , Lee Kil Sung , Cha Cheon Seok
Published: March 2009

In this study, the impact collapse tests were performed to investigate collapse
characteristics of Al/CFRP member which were composed of aluminum members wrapped with
CFRP (Carbon Fiber Reinforced Plastics) outside aluminum member. Aluminum members absorb
energy by stable plastic deformation, while CFRP members absorb energy by unstable brittle failure
with higher specific strength and stiffness than those in the aluminum member. In an attempt to
achieve a synergy effect by combing the two members, Al/CFRP members were manufactured and
impact collapse tests were performed for the members. Based on the respective collapse
characteristics of aluminum and CFRP members, the collapse modes and energy absorption capability
were analyzed for Al/CFRP member which have different fiber orientation angle of CFRP. Test
results showed that the collapse of the Al/CFRP member complemented unstable brittle failure of the
CFRP member due to ductile nature of the inner aluminum member and the fiber orientation angle of
Al/CFRP members influence energy absorption capability and collapse mode.
Mechanical Properties of Silk Fiber Reinforced Polymer Composites with Carbon Nanotubes
Authors: Kim Hun Sik , Park Byung Hyun , Yoon Jin San , Jin Hyoung Joon
Published: March 2009

Biodegradable composites consisting of poly(butylene succinate) (PBS) and carbon
nanotube (CNT)-coated silk (Bombxy mori) fibers were prepared by melt compression molding. The
results show that even with addition of a small amount of reinforcements (about 3 wt%), the tensile
strength and modulus of the composites improved dramatically by about 195% and 121%,
respectively, compared with PBS. The improvement is attributed to stronger interfacial shear strength
between the PBS matrix and the CNT-coated surface of silk fiber, which was obtained by the
microbond droplet test between PBS matrix and fibers. Furthermore, scanning electron microscopy
images indicated that the interfacial adhesion between PBS matrix and CNT-coated fiber improved in
the composites.
The Effect of Oxygen on Verbal Performance : An fMRI Study
Authors: Chung Soon Cheol , You Ji Hye , Lee Bong Soo , Tack Gye Rae , Kim Sin , Son Sang Hee
Published: March 2009

This study aimed to investigate the hypothesis that administration of the air with 30%
oxygen compared with normal air (21% oxygen) enhances verbal cognitive functioning through
increased activation in the brain. Nine male college students participated in the study. The experiment
consisted of two runs, one for verbal cognition task with normal air (21% oxygen) and the other for
verbal cognition task with hyperoxic air (30% oxygen). Functional brain images were taken with a 3T
MRI using the single-shot EPI method. From the results of the verbal behavioral analysis, the
accuracy rate was enhanced with 30% oxygen administration when compared to 21% oxygen. The
activities were observed at the occipital, parietal, temporal and frontal lobes during both 21% and
30% oxygen administration. There were more activations observed at the right middle frontal gyrus,
right inferior frontal gyrus, right superior frontal gyrus, cingulate gyrus, left middle temporal gyrus,
and left fusiform gyrus with 30% oxygen administration. These results suggest that a higher
concentration of breathed oxygen increases saturation of blood oxygen in the brain, and facilitates
verbal performance.
Stress Intensity Factor of Notch/Crack Configuration under Bending Load for Brittle Materials
Authors: Wang Feng Hui
Published: March 2009

Stress intensity factor of crack ahead of notch is important for understanding
the failure of this kind structure. In this paper, a model is proposed to calculate the stress
intensity factor of crack ahead notch configuration under bending load, the modeling
value were verified by the data from literatures and experimental data of this paper, the
trend of the value from model is agreement with that from experiments.
Experimental Study on Mechanism of Crack Coalescence between Two Pre-Existing Flaws under Dynamic Loading
Authors: Zhang Ping , Li Ning , He Ruo Lan
Published: March 2009

More and more engineering practice indicates rock mass is prone to lose its stability
through crack coalescence under dynamic loading, such as blasting and earthquake. However, the
crack coalescence pattern of rock specimens containing two or more flaws has not been studied
comprehensively under dynamic loading. In this paper, the mechanism of the crack coalescence and
peak strength of sandstone-like materials containing two parallel flaws are studied under uniaxial
static and dynamic loading with strain rates 1.7×10-5 s-1 and 1.7×10-1 s-1. Through the comparisons of
the propagation length, coalescence pattern of the cracks and strength increase of the pre-cracked
specimens under static and dynamic loading, the dynamic response of the crack coalescence is found
different from static loading under different geometric setting of the flaws. The inertia effect of the
crack propagation is revealed under dynamic loading, that is to say, the growth of the secondary
cracks tends to the original propagation direction, and the direct and immediate coalescence is taken
place easily between two pre-existing flaws, which is different from the kinking coalescence under
static loading. So, the inertia effect of the crack propagation is regarded as the main cause of the
strength increase of the brittle material under dynamic loading for medium strain rates. In virtue of the
explanation, another cause of the mode II shear fracture occurred under earthquake is opened out.
Experimental Simulation of Neutron Irradiation Damage in Reactor Pressure Vessel Steels
Authors: Hashmi Fahim , Wu Su Jun , Li Huan Xi
Published: March 2009

Degradation of reactor pressure vessel (RPV) steels due to neutron irradiation embrittlement is directly related to safety and life of the nuclear power plant (NPP). In order to ensure structural integrity and safe operation of NPP, surveillance programs are conducted to monitor and predict the changes in RPV materials. Availability of irradiated specimen from RPV or irradiation of specimens under simulated conditions of RPV for conducting fracture toughness tests remains a major problem in surveillance programs. In order to resolve this problem, various methods are adopted to experimentally simulate the effect of neutron irradiation on mechanical behavior of RPV steels using electron irradiation, thermal aging, strain hardening, combined quenching and hardening and pre-straining combined with heat treatment. This paper presents a review of the existing research on experimental simulation of neutron irradiation damage through various methodologies and discusses the future scope of their application in plant safety and life assessment of RPV’s.
Fatigue Life Evaluation of Rubber Components for Automobile Vehicles
Authors: Woo Chang Su , Kim Wan Doo , Kwon Jae Do
Published: March 2009

The interest of the fatigue life for rubber components was increasing according to the
extension of warranty period of the automotive components. In this study, the fatigue lifetime
prediction methodology of the vulcanized natural rubber was proposed by incorporating the finite
element analysis and fatigue damage parameter determined from fatigue tests. Finite element
analysis of 3D dumbbell specimen and rubber component was performed based on a hyper-elastic
material model determined from the mechanical tests. The Green-Lagrange strain at the critical
location determined from the finite element analysis was used for evaluating the fatigue damage
parameter of the natural rubber. Fatigue tests were performed using the 3D dumbbell specimens and
rubber component with different levels of maximum strain and various load. Fatigue life curves
can be effectively represented by a following single function using the maximum Green-Lagrange
strain. Fatigue lives of the natural rubber are predicted by using the fatigue damage parameters at
the critical location. Predicted fatigue lives of the rubber component for automobile vehicle agreed
fairly with the experimental fatigue lives.