bluuebunny/crossref_metadata_2025 huggingface dataset:
Research of 3D-CFD Simulation on a Large Sized Pit Type Carburizing Furnace
Authors: Zhang Wei Min , Ma Ye , Li Lin Lin
Published: March 2009

A fluid dynamic model was set up to describe the flow field of gas in a large sized pit type carburizing furnace when large sized gears were being carburized. The commercial software Fluent was adopted to carry out 3 dimensional computational fluid dynamics (3D-CFD) simulations of the gas flow field under different, actually four kinds of , furnace designs in this article. The flow fields of the carburizing gas around the part were analyzed. According to the simulations and analysis, it was shown that the number of fans on gear’s carburizing is not a primary factor, using a air inducting tub can improve the carburizing process significantly and proper loading tray design can also be positive. The results indicate that the simulation provides a reference to the furnace’s design optimization.
A Finite Element Model for Heat Treatment of Steel Alloy
Authors: Cho Yi Gil , Im Young Roc , Kim Gyo Sung , Han Heung Nam
Published: March 2009

A finite element model was developed to simulate the deformation, temperature and phase transformation behavior in high carbon steels. The heat capacity of each phase and the heat evolution due to phase transformation were obtained from the thermodynamic analysis of S45C, 50CrV4 and SK85 steels. Phase transformation kinetics of the steels were derived from continuous cooling experiments. An additivity technique was applied to a modified Johnson-Mehl-Avrami equation to analyze continuous cooling curve. To predict the strain due to TRansformation Induced Plasticity (TRIP), a variant selection model for diffusionless transformation and an accelerative creep model for diffusional transformation were adopted. In order to calculate the deformation behavior, the elastic strain, the volumetric strain due to thermal contraction and phase transformation, the plastic strain and the TRIP strain were taken into account. Using the finite element model developed in this study, the temperature-phase-deformation behavior of the high carbon steels was calculated.
Computer Simulation Evaluation of Carburized Helical Gear
Authors: Sugimoto Tsuyoshi , Watanabe Youichi
Published: March 2009

Carburizing and quenching process conditions must be optimized to minimize quenching distortion and dispersion; this includes the parts racking design used for quenching. The racking positions of the gear determine the distortion of the tooth through the effect of the cooling condition on the surface. We analyzed gear tooth distortion on the carburizing-oil quenching process. The cooling dispersion at the gear surface was measured. The heat transfer coefficient was calculated by a design of experiment study, adaptive simulated annealing, and non-linear sequential programming on quadratic language using a cooling simulation model of the gear tooth under four quenching conditions. The coefficients were attached to the boundary condition of the gear model surface, and the gear distortion was investigated using a five-model simulation that used both a homogeneous model and the four heterogeneous surface cooling models. Evaluation of the differences in accuracy between these simulations showed that the shape accuracy in the heterogeneous simulations was better than in the homogeneous one. To calculate the distortion tendency accurately, we need to assign a detail cooling condition to the gear surface.
Influences of Elastic Stress and Interfacial Kinetic Barrier on Phase Evolution Paths of Thin-Film Diffusion Couples
Authors: Huh Joo Youl , Hong Jong Pa
Published: March 2009

An explicit, finite difference scheme was used to examine the effects of coherency stresses and interface kinetic barriers on the phase evolution of a binary, thin-film diffusion couple. Thin-films, initially consisting of alternating layers of two terminal phases, α and γ, were held at a temperature at which the formation of an intermediate phase, β, at α/γ interface was thermodynamically probable. When either the coherency stresses or interface kinetic barriers are present, the interfacial compositions become time-dependent and, thus, the formation of the thermodynamically stable β phase can be kinetically prohibited at the early stage of the evolution. Even if the initial α/γ thin-films have the same overall composition, the coherency constraint can result in different final equilibrium states depending on either the initial compositions of the α and γ phases or the relative magnitudes of the interfacial kinetic barriers. When both the coherency constraint and interfacial kinetic barriers are present, an intermediate phase can repeatedly form and disappear during the evolution.
Interface Development in Sintering of Roll Bonded Metal Laminates
Authors: Lee Malik , Wuhrer Richard , Yeung Wing Yiu
Published: March 2009

Metal laminates have experienced rapid development in many engineering applications
and generally possess enhanced properties with improved service performance. Roll bonding is a
major technique used in manufacture of metal laminates. This paper is to investigate the effects of
atomic diffusion on the interface development of roll bonded metal laminates in the sintering heat
treatment process. Copper/aluminium bi-metal laminates were prepared by roll bonding at 430oC
with a 40% rolling reduction in a single pass. Sintering was then applied at 450oC for various
periods. It was found that multi-phase interfacial layers developed in the sintering process and
shifted towards the aluminium metal with increasing sintering time. Composition profiles of the
metallic elements were carefully determined across the interfacial area of the bonded material.
Interdiffusion coefficients of the metallic elements were determined using Boltzmann-Matano
analysis. The results were correlated with the multi-phase development in the interfacial area.
Creep and High Temperature Fatigue Resistance of Ti-6Al-4V Modified by Duplex Plasma Carburization/CrN Coating
Authors: Park Y.G. , Wey M.Y. , Hong Sun Ig , Ikenaga M.
Published: March 2009

In this study, a newly developed duplex coating method incorporating plasma carburization and CrN coating was applied to Ti-6Al-4V and its effects on the creep and high temperature fatigue were investigated. The creep resistance was enhanced significantly by the duplex surface treatment. The stress exponent and the activation energy for creep of duplex-surfacetreated Ti-6Al-4V at 510~550°C were measured to be 8.0-9.5 and 230 to 280 kJ/mol, respectively. Both the stress exponent and the activation energy were not appreciably changed by surface modification suggesting that the creep deformation mechanism is not modified by the surface treatments, but rather dominated by the deformation of the Cu matrix. In the temperature range of the present study, the β phase acts as an athermal obstacle and increases the athermal strengthening component, which would increase the creep resistance and the stress exponent. Since the creep deformation proceeds by overcoming thermal obstacles in the matrix, the activation energy is not appreciably modified by the presence of the β phase. The fatigue of duplex-surface-treated Ti-6Al- 4V improved significantly over that its non surface-treated counterpart. The initiation of fatigue cracks is likely to be retarded more effectively by the presence of hard and strong Cr layers on the surface, resulting in life time enhancement.
Effects of Heating Time, Electric Power and Frequency on Bending Fatigue Strength of Induction Hardened Gears
Authors: Miyachika Kouitsu , Oda Kazuteru , Katanuma Hideaki , Iwanaga Jun , Oda Satoshi
Published: March 2009

The measurement of hardened layer and the bending fatigue test of S35C and S45C steel gears induction-hardened under various heating conditions were carried out, and then profiles of hardened layer and S-N curves (bending fatigue strength) were obtained. Effects of the heating time, the electric power and the frequency on profiles and micro-structures of hardened layers of gears were examined. Relationship between the bending fatigue strength and the profile of hardened layer was determined. Optimum heating conditions for the bending fatigue strength of induction-hardened S35C and S45C steel gears were indicated.
Improved Pore Array and Uniformity of Anodic Aluminum Oxide Template by Using a Rapid Thermal Anneal Process
Authors: Lim Dong Gun , Kim Dong Hee , Kim Jin Kwang , Kwon Odae , Yang Kea Joon , Park Joon Hoon , Lee Jung Il
Published: March 2009

Ordered nanostructure materials have received attention due to their unique physical properties and potential applications in electronics, mechanics and optical devices. To actualize most of the proposed applications, it is quite important to obtain highly ordered nanostructure arrays. The well-aligned nanostructure can be achieved by synthesizing nanostructure material in the highly ordered template. In this paper, Anodic Aluminum Oxide (AAO) templates were fabricated using a two-step anodization process with pretreatment such as electropolishing and annealing. To reduce process time and get well-aligned pore array, rapid thermal anneal by an IR lamp was employed in vacuum state at 500oC for 2 hours. The pore array is comparable to a template annealed in vacuum furnace at 500oC for 30 hours. The well-fabricated AAO template has a mean pore diameter of 70 nm and the interpore distance of 100nm. The pore density can be as high as 1.2×1010cm-2.
The Properties of Ti-Doped ZnO Films Before and After Annealing in the Different Atmosphere
Authors: Lin Su Shia , Huang Jow Lay
Published: March 2009

A radio frequency power (r.f.) of 200W was supplied to ZnO target, and a direct current (d.c.) power of 30W was supplied to Ti target for the preparation of Ti-doped ZnO (ZnO:Ti) films. The Ti content was controlled by d.c. power, and maintained at 1.1 at.% as measured by XPS. The as-deposited ZnO:Ti films had polycrystalline structure and low resistivity (9.69×10-3-cm). After annealing in N2 or O2, ZnO:Ti films exhibited poor crystallinity, and the resistivity increased substantially. The lower optical energy gap (3.31 eV) could be obtained as ZnO:Ti film annealing in O2. However, the weak absorption in the visible region of the spectrum terminated at shorter wavelengths with the onset of the ultraviolet absorption edge for all samples. Annealing in N2 or O2 did not improve the properties of ZnO:Ti films.
Microstructural Change and Martensitic Transformation in a Rapidly Solidified Cu-Al-Ni Based SMA Ribbons with Heat Treatment
Authors: Jee Kwang Koo , Park Jin Seong , Lee Y.S. , Jang Woo Yang
Published: March 2009

The effects of flash-heating and aging on the microstructure and transformation
characteristics has been studied in Cu-Al-Ni based melt-spun ribbons. When the as-spun ribbon,
stabilized due to higher Al content and fast cooling, is flash-heated at 750 °C, the β1 parent phase is
partially retained. Even though flash-heating temperature is increased upto 850 °C, a little β1 parent
phase with lager grains above 10 μm is still retained. The Ms temperature is increased with
increasing flash-heating temperature due to the decrease of grain constraint within grown grains.
However, the greater part of β1 parent phase with smaller grains of 2 ~ 3 μm is transformed to
martensite in the initial stage of aging at 200 °C. The Ms temperature of the ribbon with smaller
grains is higher than that of the ribbon with larger grains. It is considered that the increase of Ms
temperature is caused to the disappearance of lattice defects introduced during melt spinning by
aging at 200 °C rather than grain growth.
Synthesis and Dilatometric Study of Ca(Sr, La)TiO3 Prepared by Solution Combustion Synthesis (SCS)
Authors: Jung Choong Hwan , Park Ji Yeon , Ryu Woo Seog
Published: March 2009

La and Sr have recognized as elements of high level radioactive wastes immobilized by
solid solution with CaTiO3. For forming solid solution with CaTiO3, the solution combustion
synthesis (SCS) process was applied and the powder characteristics and sinterability were
investigated. The proper selection of the type and the composition of fuels are important to get the
crystalline of CaTiO3. When glycine or the mixtures of urea+citric acid with stoichiometric
composition was used, the solid solutions of Ca(La, Sr)TiO3 were entirely produced. The
combustion synthesized powder seemed to have a good sinterability with the linear shrinkage of
more than 23% up to 1400oC, while that of the solid state reacted powder was less than 19% at the
same conditions.
Phase Analysis of the Precipitates in an Alloy 600/182 Weld
Authors: Lim Yun Soo , Kim Hong Pyo , Jung Man Kyo , Kim Joung Soo
Published: March 2009

The precipitates in the base metal and the fusion zone of an Alloy 600/182 weld were characterized through a transmission electron microscopy. Precipitates in the Alloy 600 base metal were identified as Cr7C3. On the other hand, (Nb,Ti)C, Al-rich and Ti-rich oxides were found on the dendritic interfaces, and tiny Cr-rich M23C6 were distributed on the grain boundaries in the Alloy 182 fusion zone.
Role of Organic Modifiers of Master Batches and Layered-Silicates in Styrene-Butadiene Rubber Nanocomposites
Authors: Lee Kyoung Sub , Han Mi Jeong
Published: March 2009

Styrene-butadiene rubber (SBR) nanocomposites were prepared from organically
modified montmorillonite (OMMT). To enhace the dispersion properties of OMMT in SBR matrix,
polybutadiene was modified with tetramethyl siloxane substituted with benzylamine, and the master
batches of those were prepared by a solution process using tetrahydrofuran. SBR/master batch
nanocomposites could be obtained by melt-compounding followed by hot-press vulcanization. Xray
diffraction (XRD) studies revealed that the interlayer distances of OMMT were increased and
the nanocomposites had the intercalated and exfoliated structures of OMMT by the
nanocomposition of SBR with the master batch. Mechanical and dispersion properties of the
nanocomposites from the master batch are superior to those of nanocomposites without master
batch.
Preparation of Porous Graphite Using Template of Kenyaite
Authors: Jeong Soon Yong
Published: March 2009

Porous graphite was synthesized by removal of template after pyrolysis of PFO
(pyrolized fuel oil) using kenyaite template with cobalt catalyst. Pyrolysis was conducted for 3-18
hr at 900-1350°C. Porous graphite was synthesized at 900°C after pyrolizing during 3 h. Porous
graphite was well crystallized with increasing amount of cobalt. Specific surface area was the range
of 274-491 m2/g depending on pyrolysis conditions.
Preparation and Characterization of Surface Modified MCF (Mesostructured Cellular Foam) Silica for the Immobilization of Heteropolyacid Catalyst
Authors: Kim Hee Soo , Jung Ji Chul , Kim Pil , Lee Kwan Young , Yeom Sung Ho , Song In Kyu
Published: March 2009

Mesostructured cellular foam (MCF) silica was synthesized via surfactant templating route. The surface of MCF silica was then modified by grafting 3-aminopropyl-triethoxysilane (APTES) to have the positive charge, and thus, to provide sites for the immobilization of H3PMo12O40 (PMo12). By taking advantage of the overall negative charge of [PMo12O40]3-, PMo12 catalyst was chemically immobilized on the amine-functional group of surface modified MCF (SM-MCF) silica as a charge matching component. It was found that pore structure of MCF silica was maintained even after the surface modification and the subsequent immobilization of PMo12. It was also revealed that PMo12 species were finely and molecularly dispersed on the SM-MCF silica via chemical immobilization.
Adsorption Characteristics of Nitrogen and Oxygen onto Ion-Exchanged X-Type Zeolite
Authors: Jeong Heon Do , Kim Dong Sik , Kim Kweon Ill , Song In Kyu
Published: March 2009

Adsorption characteristics of nitrogen and oxygen onto the ion-exchanged X-type zeolites
through pressure swing adsorption (PSA) process were investigated. On the basis of Na-X zeolite, a
series of ion-exchanged X-type zeolites containing Ag, Li, Ca, Sr, Br, and K were prepared and
investigated in this work. It was revealed that the ion-exchanged X-type zeolites showed a remarkably
improved and selective adsorption capability for nitrogen. At equilibrium pressure under 0.5 atm,
adsorption capability for nitrogen was decreased in the order of Ag-X > Li-X > Sr-X > Ca-X > Na-X
> Ba-X > K-X. At equilibrium pressure over 1 atm, however, the capability was decreased in the order
of Li-X > Ag-X > Sr-X > Ca-X > Na-X > Ba-X > K-X. The Li-X zeolite exhibited the selective
adsorption capability for nitrogen in the air separation process at high pressure. The separation factor
for nitrogen/oxygen (= N2/O2) in the Li-X zeolite was ca. 13.
Microwave-Assisted Combustion Synthesis of α-Alumina and Magnesium Aluminate Spinel Nanocomposite Powders
Authors: Jung Young Mi , Kim Sang Woo
Published: March 2009

Microwave-assisted combustion synthesis of α-alumina-magnesium spinel nanocomposite powders from a route using ammonium aluminum carbonate hydroxide (AACH) as a precursor was studied. γ- to α-phase transformation temperature of microwave-assisted alumina composite powders is lowered by 100°C compared to that of normal heat-treated alumina composite powders. The crystallite size of the microwave-assisted composite powders was considerably decreased from 42 nm to 29 nm compared to that of the normal heat treated composite powders. Nanosized α- alumina-magnesium aluminate composite powders were successfully synthesized by microwave-assisted combustion under nitrogen atmosphere at 1050°C.
Synthesis of CdS Nanocrystallites in Polymer Matrix: Sui-Generis Approach
Authors: Kanade K.G. , Hawaldar Ranjit R. , Mulik Uttam , Kale B.B. , Amalnerkar Dinesh
Published: March 2009

We offer sui-generis strategy for synthesis of nanosized chalcogenide semiconductors in polymer matrix by a novel polymer-inorganic solid-state reaction. In our previous report, the rationale of this strategy has been successfully established by the solid-state reaction between CdI2 and an intentionally chosen engineering thermoplastic, namely, polyphenylene sulphide (PPS). In the pursuit of this work, we explored the possibility of using other cadmium salts viz cadmium nitrate, cadmium chloride and cadmium acetate in place of cadmium iodide for the envisaged solidstate reaction with PPS. All the reactions were carried out at the melting temperature of PPS (285oC) in 1:1 and 10:1 molar ratios of polymer to cadmium salt. The resultant products were characterised by XRD, TEM-SAED and DRS. It is observed that only cadmium nitrate yielded CdS nanocrystallites (average size of 15nm) entrapped in modified polymer matrix in a competing behaviour with cadmium iodide when reacted in 10:1 molar ratio while (i) cadmium acetate leads to the formation of only cadmium oxide and (ii) cadmium chloride exhibits grossly incomplete solid state reaction yielding understated quantity of CdS when reacted with PPS.
A Study of Surface Modification on Adsorption Behaviors of Nanoporous Carbon
Authors: Kim Byeoung Ku , Lee Young Seak , Ryu Seung Kon , Kim Byung Joo , Park Soo Jin
Published: March 2009

In this work, to introduce polar functional groups on carbon surfaces, activated carbon fibers (ACFs) were treated by nitric acid in order to enhance the adsorption capacity of propylamine which was one of toxic gases in cigarette smoke. It was found that the polar functional groups were predominantly increased up to 2.0 M of nitric acid, resulting in the increase of total surface acidity. It was found that the adsorption amount of propylamine of the modified ACFs was increased around 17% after a nitric acid treatment. From the XPS results, it was observed that propylamine was reacted with strong or weak polar (acidic) groups, such as COOH, -COO or OH existed on the ACF surfaces.
The Effect of Ni-Co Catalyst Composition on the Yield and Nanostructure of Carbon Nanofibers Synthesized by CVD
Authors: Singh B.K. , Ryu Ho Jin
Published: March 2009

Carbon nanofibers (CNFs) with different compositions (MgONixCoy, x and y= 0.0 to 0.5) and morphologies were synthesized by the CVD method using H2/C2H2 gas over a bimetallic MgO supported catalyst. The techniques such as Raman spectroscopy, SEM and TEM were used to characterize the as-synthesized nanofibers. The maximum yield for the longest of CNFs having widest diameter was obtained with MgONi0.0Co0.5 catalyst at 600°C, while bi-metallic composition MgONi0.25Co0.25 produced CNFs with good crystalline features. The nanostructure of the CNFs with MgONi0.5Co0.0 generates onion/flake like structure.
Effect of CNTs Support Diameter on Pt Particles Size and Distribution
Authors: Kim Yong Hwan , Seo Yon Ki , Cho Young Rae , Kim Kwang Ho , Chung Won Sub
Published: March 2009

The Platinum catalysts on the carbon nanotubes(CNTs) supports of various diameters
were prepared by wet impregnation method using H2PtCl6 precursor. The samples using 100nm,
15~20nm, 10~15nm and 5~10nm diameters of CNTs and carbon nanofibers(CNFs) are named Pt/t-
CNFs, Pt/MWNTs20, Pt/MWNTs10 and Pt/MWNTs5, respectively. The effects of CNTs diameter
on the Pt particle size and distribution were investigated by the means of powder XRD and TEM
observation. In addition, the electro-catalytic characteristics for methanol electro-oxidation were
estimated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)
techniques. The average size of Pt particles increases as follows; Pt/MWNTs10 < Pt/MWNTs5 <
Pt/MWNTs20 < Pt/t-CNFs. The electro-catalytic characteristics of Pt/MWNTs10 and Pt/MWNTs20
are found to be superior in comparison with the others. For preparation of the most effective
supported Pt catalyst, the optimum diameter of CNTs support in the range of 10-20nm, is needed.
Preparation of Cu/ZnO for Fabrication of a Micro Methanol Reformer
Authors: Cha Hong Seock , Kim Tae Gyu , Kwon Se Jin
Published: March 2009

Three synthesis procedures of Cu/ZnO catalyst for steam reforming of methanol were
tested for loading in a micro reactor. The best procedure that resulted in the strong adhesion to the
wafer was determined out of the tested procedures. The molecular structure of the synthesized
catalyst was examined by XRD and its performance in methanol conversion was measured. A micro
fabrication method that incorporates the catalyst loading and micro structure processing was
developed. A MEMS methanol steam reformer was built by this process and the completed device
resulted in methanol conversion of 93%.
Preparation of Ethyl-Cellulose Nanofibers via An Electrospinning
Authors: Jeun Joon Pyo , Lim Youn Mook , Choi Jae Hak , La Hyun Shil , Kang Phil Hyun , Nho Young Chang
Published: March 2009

Ethyl-cellulose (EC) nanofibers were fabricated by an electrospinning of an EC solution
with a 6-12 wt% concentration. Fiber morphology was observed under a scanning electron
microscope and the effects of instrument parameters including the solution concentration, flow rate
and electric voltage were investigated.
Sedimentation Properties of TiO2 Nanoparticles in Organic Solvents
Authors: Woo S.H. , Lee Min Ku , Rhee Chang Kyu
Published: March 2009

In this study, the colloidal stability and sedimentation behavior of crystalline TiO2
particles (∼300nm) in various organic solvents have been investigated by means of a backscattered
light flux profile (Turbiscan) and a zeta potential measurement. The backscattered light flux profiles
revealed that the TiO2 nanoparticles were readily sedimented in water, methyl alcohol, and ethyl
alcohol due to a flocculation-induced particle growth, while a particle coalescence and a
sedimentation of the TiO2 nanoparticles were hardly observed in isopropyl alcohol. The measured ζ
potentials verified the differences of the colloidal stabilities of the TiO2 particles in the organic
solvents, showing a good correlation with the migration velocity.
Nanostructured Thin films of Anthracene by Liquid-Liquid Interface Recrystallization Technique
Authors: Hawaldar Ranjit R. , Funde A.M. , Bhange D. , Ramaswamy V. , Jadkar Sandesh R. , Sathaye S.D. , Mulik Uttam , Amalnerkar Dinesh
Published: March 2009

Herein, we report the fabrication of anthracene nanostructures and, in turn, their thin films at the air-water interface by recrystallization at the liquid-liquid interface. This method is simple, inexpensive and allows the deposition of anthracene nanoparticulate thin films on large and a variety of substrates. The virgin films were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Hot Stage Polarizing Microscopy and UV-Visible spectroscopy. Interestingly, it was found that these thin films are comprised of nanosized bushy clusters of anthracene molecules as revealed by TEM. Also, with increase in the thickness of the films, the formation of irregular microtapes was evinced by SEM. The absorption spectra reveals the presence of 2 excitonic peaks for the lowest dip sample (10 dips) whereas the spectra recorded for higher dip samples (20 dips, 30dips, 40dips) closely match with that of pure anthracene in chloroform solution. The dramatic reduction in the melting point as revealed by hot stage polarizing microscopy is the salient feature of the work.
A Gas Control by Metal Nanoclusters-Supported Porous Carbon Nanofibers
Authors: Kim Byung Joo , Lee Young Seak , Park Soo Jin
Published: March 2009

In this work, we prepared porous graphite nanofibers (PCNFs) from herringbone-type
graphite nanofibers, and nano-sized transition metals such as copper metal, were loaded on the
PCNFs by a metal electroplating in order to prepare novel catalysts for the control of toxic gases, such
as hydrogen chloride. From experimental results, PCNFs had around 2000 m2/g of a specific surface
area, and it was decreased slightly after metal loading. In case of metal content, we could control
them from less 3 to over 30 wt% by means of the plating time and current density applied. After the
metal loading, all samples having transition metal nanoclusters showed higher efficiency of HCl
removal than that of samples without metals. However we also found that some samples having
excessive metal content showed a decrease in the efficiency of HCl removal. This result meant that
one of key technologies was both to find optimal metal content and to remain high specific surface
area of substrates.
Ion Conducting Behaviors of Polymeric Composite Electrolytes Containing Mesoporous Silicates
Authors: Kim Seok , Lee Sung Goo , Park Soo Jin
Published: March 2009

Polymeric composite electrolytes (PCE) based on poly(ethylene oxide) (PEO) and
mesoporous silicates as a filler material were fabricated, and investigated for understanding the
effects of filler addition into the polymer matrix on the ionic conductivity. For a lithium battery
application, it is necessary to increase ion conductivity of PCE by modification of microstructure.
The ionic conductivity was enhanced with increasing MCM-41 contents due to the decreased
crystallinity of PEO. Furthermore, the regular mesoporous structure could be functioned as an ion
transfer channel for high ion mobility.
Preparation and Characterization of Activated Carbon Nanofiber Webs Containing Multiwalled Carbon Nanotubes by Electrospinning
Authors: Park Soo Jin , Im Se Hyuk , Rhee John M. , Lee Young Seak
Published: March 2009

Electrochemical double layer capacitors (EDLCs) are promising high power energy
sources for many different applications where high power density, high cycle efficiency and long
cycle life are needed. However, because the energy density of EDLCs is small compared to that of
rechargeable batteries one needs to increase the capacitance of EDLCs. The nanofiber diameters
range from 50 nm to 400 nm, depending on the concentration of polymer solution types,
tip-to-collector distance, applied voltage, and viscosity of the solution. The main advantage of the
electrospinning process is that it is a simple means to prepare continuous fibers with unusually large
surface to volume ratios and pore structure surfaces. So, feature of nanofiber webs are the high
specific surface area developed by creating pores on the nanofiber surface. In this work, the
multiwalled carbon nanotubes embedded polyacrylonitrile solutions in N,N-dimethylformamide
(DMF) were electrospun to be webs consisting of 350 nm ultrafine nanofibers, which were used to
produce a series of activated carbon nanofibers with developed mesoporosity and high electrical
conductivity through stabilization, carbonization-activation processes.
Microstructure and Thermal Stability of Carbon Nanotubes Dispersed Alumina Nanocomposites Prepared by Spark Plasma Sintering
Authors: Choa Yong Ho , Yoo Seung Hwa , Yang Jae Kyo , Song Chul Kyu , Oh Sung Tag , Yoon Se Joong , Kang Sung Goon
Published: March 2009

The influence of relative density on the thermal stability of CNTs-dispersed Al2O3 nanocomposites has been investigated by using thermogravimetric analysis (TGA). TGA revealed that the onset temperature for weight loss increased with an increasing sintering temperature and CNT content. By taking account of the XRD and SEM results, it is suggested that the weight loss is caused by a decomposition of CNTs phase by oxidative atmosphere. The difference in thermal stability was explained by the porosity effect on the oxidation and decomposition behavior of CNTs, because the open pores promote the chemical reaction and gas flow of reactants.
Properties of Dispersion Strengthened Cu-TiB2 Nanocomposites Prepared by Spark Plasma Sintering
Authors: Kwon Dae Hwan , Nguyen Thuy Dang , Dudina Dina V. , Kim Ji Soon , Yum Young Jin , Kwon Young Soon
Published: March 2009

Preparation of titanium diboride reinforced copper matrix composites with high conductivity and mechanical strength was developed based on in situ produced powders. The effect of the titanium diboride content on the mechanical properties of the bulk material produced from the powders by Spark Plasma Sintering technique was studied. Increasing titanium diboride content from 2.5 up to 7.5 wt.% resulted in a 1.5-fold increase in yield strength, tensile strength and hardness and 5-fold increase in wear resistance with only 10% decrease in conductivity.
Preparation of TiO2 Nanorod Arrays by Electrophoretic Deposition of Titania Nanoparticles
Authors: Qi Zhang , Kim Yong Joo , Lee Wan In
Published: March 2009

The TiO2 nanorod arrays were fabricated by the electrophoretic deposition (EPD) of the 4.5 and 7 nm-sized anatase titania nanoparticles using the anodized aluminum oxide (AAO) as the template. Each of the TiO2 nanoparticle was plus-charged by adjusting the pH of the electrolyte. The growth rate of TiO2 nanorod arrays with this new method was dramatically higher than that of the arrays obtained from the conventional EPD method employing sol-gel solutions. In addition, the robust anatase-phase TiO2 nanorod arrays were obtained without post-thermal treatment. The scanning electron microscope (SEM) images showed that the titania nanoparticles were tightly interconnected to form the highly uniform and well-organized TiO2 nanorod arrays. The diameter of the TiO2 nanorod arrays was 55~58 nm with the length of 15 0m, which corresponded to the size of AAO templates.
Synthesis of SiOx Nanowires through the Thermal Heating of Au-Coated Si Substrates
Authors: Kim Hyoun Woo , Shim S.H. , Lee Jong Woo
Published: March 2009

We have demonstrated the growth of SiOx nanowires by the simple heating of the Au-coated Si substrates. We used X-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and transmission electron microscopy to characterize the samples. The as-synthesized SiOx nanowires had amorphous structures with diameters in the range of 10-70 nm. We have discussed the possible growth mechanism.
Economic Evaluation of Maintenance Strategies for Steam Generator Tubes Using Probabilistic Fracture Mechanics and a Financial Method
Authors: Isobe Yoshihiro , Sagisaka Mitsuyuki , Yoshimura Shinobu , Yagawa Genki
Published: March 2009

As an application of probabilistic fracture mechanics (PFM) and a financial method, a
risk-benefit model was developed for the purpose of optimizing maintenance activities of steam
generator (SG) tubes used in pressurized water reactors (PWRs). To justify whether or not it is
worth while implementing the selected maintenance strategy in terms of an economic point of view,
net present value (NPV) was calculated as an index which is one of the most fundamental financial
indices for decision-making based on the discounted cash flow (DCF) method.
Finite Element Alternating Method for Interacting Surface Cracks
Authors: Kamaya Masayuki , Nishioka Toshihisa
Published: March 2009

The finite element alternating method (FEAM), in conjunction with the finite element analysis (FEA) and the analytical solution for an elliptical crack in an infinite solid subject to arbitrary crack-face traction, can derive the stress intensity factor (SIF) of surface cracks by using the FEA results for an uncracked body. In the present study, the FEAM was applied to evaluations of SIF for noncoplanar multiple surface cracks. The SIF was evaluated for two surface cracks of dissimilar size, and three crack of the same size. The results suggested that the interaction is greatly affected by the relative crack size and negligible when the difference in the crack size is large enough, and the interaction can be evaluated by taking into account the adjacent cracks even if there are many cracks around them. Finally, the crack growth simulations were conducted and a possibility of the direct evaluation of influence of interaction between adjacent crack without using the combination rules was revealed.
Aging Management of Nuclear Power Plants in Korea
Authors: Jin Tae Eun , Park Heung Bae , Kim Hho Jung
Published: March 2009

Kori Unit 1, which is the oldest nuclear power plant (NPP) in Korea has been operated
since 1978. In addition, 10 other NPPs have been operating more than 10 years. As the number of
aging plants rise, public concern over the safety of operating NPPs has increased. Periodic safety
review (PSR) in addition to the existing safety assessments are proposed by IAEA as an effective
way to verify that operating NPPs maintain the high level of safety. In this regard, the Ministry of
Science and Technology (MOST), Korea’s nuclear regulatory body, recently established an
institutional process through revision to the atomic energy act to introduce PSR. This PSR considers,
among other factors, improvements in safety standards and practices, the cumulative effects of plant
aging, operating experience, and the evolution of science and technology. In particular, the
assessment and management of plant aging is one of the major areas. It includes identification of
the system, structure and components (SSCs) for aging management, assessment of aging effects
and planning of aging management implementation program. PSR results could be one of the
procedural requirements that are utilized to renew an operating license of a NPP. This paper
describes safety assessment requirements including PSR and aging management activities in Korea.
This paper also includes the strategy and method for the application of PSR results to the aging
management and continued operation of NPPs.
Robust Sensor Placement to Measurement Noise for Structural Dynamic Systems
Authors: Oh Dong Ho , Chen Shiao Hua
Published: March 2009

Performance of experimental dynamic system identification depends on sensor placement especially when the number of sensor locations is relatively small and measurement noise is significant. We propose a method to select robust measurements based on the estimation error in modal analysis, which is one of the most popular system identification methods for dynamic systems, by defining a measure of the estimation. The measure is developed to deal with various types of sensors and with general damped systems. It is calculated from the eigenvector information obtained by finite element analysis or preliminary experiments and represents the weighted covariance of estimation error induced by measurement noise as well as the orthogonality of the projection matrix which is the corresponding submatrix of eigenvector-matrix by partially measured outputs. Effectiveness of the proposed measurement selection schemes is demonstrated by computer simulations and experiments.
An Analysis of Liquid Film Condensation Occurring Inside Rotating Heat Pipes with a Trigonal Cross Section
Authors: Kim Chul Ju , Lee Jae Seok , Kim Sung Hoon , Sung Byung Ho
Published: March 2009

Rotational heat pipes (RHPs) with a trigonal cross section was recently proposed by Lee et
al. Inside the tube of these RHPs the condensate liquid film flows down the wall in the direction
vertical to the tube axis due to centrifugal force and then the liquid returns to the evaporator along the
edges. The Nusselt analysis model of laminar film condensation was applied and the solutions were
compared with the experimental data. Concerning about the Nu vs Re the same relation was obtained
as that for vertical plate except the length scale. The thickness of condensate film was found to be
uniform along the surface due to increasing centrifugal force with surface length for a given heat flux
and rotational speed.
Wall Shear Stress in the Helical Annular Flow with Rotating Inner Cylinder
Authors: Hwang Young Kyu , Woo Nam Sub
Published: March 2009

An experimental and numerical investigation has been performed in order to study the
appearance of hydrodynamic instabilities at low bulk axial Reynolds number in the gap between two
coaxial cylinders with a diameter ratio of 0.52, 0.8 and 0.9, whose outer cylinder is stationary and the
inner one is rotating. Skin friction coefficient and wall shear stress have been measured for fully
developed laminar flows of water when the inner cylinder rotates at the speed of 0~600 rpm. The axial
component of velocity is directly affected by the radial/tangential velocity field and rotation of the
inner cylinder is found to have a strong influence on the axial velocity distribution, ultimately leading
to two maximum in the case of high eccentred inner cylinder at high rotational speeds.
Development of Digital Speckle Tomography for Analysis of Unsteady and Asymmetric Flows
Authors: Okamoto Koji , Kim Yong Jae , Ko Han Seo
Published: March 2009

A four-dimensional digital speckle tomography has been developed to analyze an initial
helium jet flow. Speckle movements from refraction of a laser beam have been captured by multiple
high-speed cameras simultaneously because a shape of a nozzle for the jet flow is asymmetric and the
initial jet flow is fast and unsteady. A cross-correlation tracking method has been used to obtain the
speckle displacements between no flow and helium jet flow from an asymmetric nozzle controlled by
a solenoid valve. The measured speckle movements have been transferred to deflection angles of laser
rays to calculate density gradients. The four-dimensional density fields for the high-speed and initial
helium jet flow have been reconstructed from the deflection angles by a developed real-time
tomography method.
Assessment of Steam Generator Tubes with Dual Axial Through-Wall Cracks
Authors: Chang Yoon Suk , Moon Seong In , Kim Young Jin , Lee Jin Ho , Song Myung Ho , Choi Young Hwan
Published: March 2009

In this paper, conservatisms of current plugging criteria on steam generator tubes are
reviewed and six new failure prediction models for dual through-wall cracks are proposed. In order to
determine the optimum ones among these local or global failure prediction models, a series of plastic
collapse tests and corresponding finite element analyses are carried out with respect to two adjacent
axial through-wall cracks in thin plates. Then, reaction force model, plastic zone contact model and
COD (Crack Opening Displacement) base model were selected as the optimum ones for integrity
assessment of steam generator tubes with dual cracks.
Ductile Fracture Behaviour of Class 2 and 3 LWR Piping and Its Implications for Flaw Evaluation Criteria
Authors: Miura Naoki , Miyazaki Katsumasa , Hisatsune Masakazu , Hasegawa Kunio , Kashima Koichi
Published: March 2009

To achieve a rational maintenance program for aged Light Water Reactor components, it is important to establish and to improve the flaw evaluation criteria. The current flaw evaluation criteria such as ASME Boiler and Pressure Vessel Code Section XI are focused on Class 1 piping which usually shows relatively higher toughness. On the other hand, flaw evaluation criteria suitable for Class 2, 3 piping with moderate-toughness are also required because some Class 2, 3 piping systems are as important to plant safety analysis as Class 1 piping. In this study, both analytical and experimental studies were conducted to provide the evaluation method of fracture loads for acceptance criteria for Class 2, 3 piping. Pipe fracture tests by four-point bending were conducted on circumferentially cracked carbon steel pipes with moderate-toughness. The Net-Section Collapse criterion overpredicted experimental maximum loads for through-wall-cracked pipes, which suggested the necessity of Z-factor. Three-dimensional finite element analysis and simplified analysis based on the reference stress method were conducted to complement the limited pipe fracture tests. It was ascertained that the reference stress method always gave moderately conservative fracture loads compared with the finite element analysis and pipe fracture tests as well. Z-factor for Class 2, 3 piping was then derived and formulated using the reference stress method. Z for Class 2, 3 piping was affected by radius-to-thickness ratio, and was higher than Z for Class 1 piping in the present codes.
Monte Carlo Simulation of Projection Electron Beam Lithography
Authors: Sun X. , Xiao P. , Ding Z.J.
Published: March 2009

We have calculated angular and energy loss distributions of electrons transmitted through masks for electron projection lithography by using a Monte Carlo simulation method. The angular and energy loss distributions are much wider in the mask stack than those in the membrane layer. The large non-scattering and non-energy-loss probabilities are also found for the membrane layer. High contrast image can thus be achieved within a small size of aperture.
Light Emitting Diode with MOS Structures Containing Multiple-Stacked Si Quantum Dots
Authors: Xu J. , Makihara Katsunori , Deki Hidenori , Kawaguchi Yoshihiro , Murakami Hideki , Higashi Seiichiro , Miyazaki Seiichi
Published: March 2009

Light emitting diode with MOS structures containing multiple-stacked Si quantum dots (QDs)/SiO2 was fabricated and the visible-infrared light emission was observed a room temperature when the negative gate bias exceeded the threshold voltage. The luminescence intensity was increased linearly with increasing the injected current density. The possible luminescence mechanism was briefly discussed and the delta P doping was performed to obtain the doped Si QDs and the improvement of EL intensity was demonstrated.
Effect of Buffer Thickness on the Formation of ZnO Nanorods Grown by MOCVD
Authors: Kim Dong Chan , Kong Bo Hyun , Kim Young Yi , Cho Hyung Koun , Lee Jeong Yong , Park Dong Jun
Published: March 2009

ZnO semiconductor has a wide band gap of 3.37 eV and a large exciton binding energy of
60 meV, and displays excellent sensing and optical properties. In particular, ZnO based 1D nanowires
and nanorods have received intensive attention because of their potential applications in various
fields. We grew ZnO buffer layers prior to the growth of ZnO nanorods for the fabrication of the
vertically well-aligned ZnO nanorods without any catalysts. The ZnO nanorods were grown on Si
(111) substrates by vertical MOCVD. The ZnO buffer layers were grown with various thicknesses at
400 °C and their effect on the formation of ZnO nanorods at 300 °C was evaluated by FESEM, XRD,
and PL. The synthesized ZnO nanorods on the ZnO film show a high quality, a large-scale uniformity,
and a vertical alignment along the [0001]ZnO compared to those on the Si substrates showing the
randomly inclined ZnO nanorods. For sample using ZnO buffer layer, 1D ZnO nanorods with
diameters of 150-200 nm were successively fabricated at very low growth temperature, while for
sample without ZnO buffer the ZnO films with rough surface were grown.
Study on Thermal Conductivity of Polyetheretherketone/Thermally Conductive Filler Composites
Authors: Kim Sung Ryong , Kim Dae Hoon , Kim Dong Ju , Kim Min Hyung , Park Joung Man
Published: March 2009

Thermal properties of PEEK/silicon carbide(SiC) and PEEK/carbon fiber(CF) were
investigated from ambient temperature up to 200°C measured by laser flash method. Thermal
conductivity was increased from 0.29W/m-K without filler up to 2.4 W/m-K with at 50 volume % SiC
and 3.1W/m-K with 40 volume % carbon fiber. Values from Nielsen theory that predicts thermal
conductivity of two-phase system were compared to those obtained from experiment.
Fabrication of Metal/Intermetallic Compound Laminate composites by Thin Foil Hot Press Process
Authors: Kim J.K. , Chung Dong Seok
Published: March 2009

Thin foil hot press process was used to fabricate metal/intermetallic compound laminate
composites to induce self-propagating high-temperature (SHS) reaction between different pure metal
sheets. In the present study, Ni/Ni-aluminide and Ti/Ti-aluminide laminate composites were
fabricated through diffusion bonding, reaction synthesis and post-heat treatment of alternatively
stacked pure Ni/Al and Ti/Al foils, respectively. Thick intermetallic layers of NiAl and TiAl3 were
formed by a self-propagating high-temperature synthesis (SHS) reaction, and thin continuous layers
of Ni3Al and TiAl were formed by a solid-state diffusion. Also, Ni/Ni-aluminide//Ti/Ti-aluminide
laminate composite, considered as a functionally gradient material, was manufactured from stacked
foils of pure Ni, Ti and Al in order of Ni/Al/Ni/.../Ni/Al /Ti/.../Ti/Al/Ti. Nb/Nb-aluminide laminate
composite was manufactured with pure Nb and Al multilayered foils, consisting of fine
Nb/Nb3Al/Nb2Al/NbAl3 layer structure.
Large-Scale Synthesis of Polymer-Stabilized Silver Nanoparticles
Authors: Lee Kwi Jong , Lee Young Il , Shim In Keun , Jun Byung Ho , Cho Hye Jin , Joung Jae Woo
Published: March 2009

The synthesis and characterization of polymer-stabilized silver nanoparticles (Ag NPs) for
water-based silver inks are studied. In order to synthesize Ag NPs with spherical shape, the
conventional polyol processes require an excess of poly(vinyl pyrrolidone) (PVP) (10 ~ 1000 times
than AgNO3) and therefore result in low productivity per reactor volume. In this study, poly(acrylic
acid) (PAA) with carboxylic acid group was used instead of PVP. Even at less molar ratio of PAA to
AgNO3 (< 2), the spherical Ag NPs with average size of 30 nm were successfully synthesized at 100
gram-scale with high reaction yield of 90%. Furthermore, the Ag NPs were dispersed into
alcohol-based solvent and then patterned into metallic lines through inkjet printing technology.
Multi-Component ZnO-In2O3-SnO2Thin Films Deposited by RF Magnetron Co-Sputtering
Authors: Son Chang Sik , Hur Jae Sung , Lee Byoung Hoon , Back Sang Yul , Lee Jeong Seop , Song Jung Bin , Choi In Hoon
Published: March 2009

Multi-component ZnO-In2O3-SnO2 thin films have been prepared by RF magnetron
co-sputtering using targets composed of In4Sn3O12(99.99%) [1] and ZnO(99.99%) at room
temperature. In4Sn3O12 contains less In than commercial ITO, so that it lowers cost. Working pressure
was held at 3 mtorr flowing Ar gas 20 sccm and sputtering time was 30 min. RF power ratio [RF1 / (
RF1 + RF2 )] of two guns in sputtering system was varied from 0 to 1. Each RF power was varied
0~100W respectively. The thicknesses of the films were 350~650nm. The composition
concentrations of the each film were measured with EPMA and AES. The low resistivity of 1-2 × 10-3
and an average transmittance above 80% in the visible range were attained for the films over a range
of δ (0.3 ≤ δ ≤ 0.5). The films also showed a high chemical stability with time and a good uniformity.