bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis on Fatigue Fracture of the Flame-Quenched 8.8Al-Bronze by Ultrasonic Vibratory Cavitation Erosion
Authors: Hong Sung Mo , Lee Min Ku , Kim G.H. , Rhee Chang Kyu , Kim K.H. , Kim Wheung Whoe
Published: March 2009

In this study the fatigue properties due to cavitation damage of flame-quenched
8.8Al-bronze (8.8Al-4.5Ni-4.5Fe-Cu) as well as current nuclear pump materials (8.8Al-bronze,
SUS316 and SR50A) have been investigated by using an ultrasonic vibratory cavitation test. For
this the impact loads of cavitation bubbles generated by ultrasonic vibratory device quantitatively
evaluated and simultaneously the cavitation erosion experiments have been carried out. The fatigue
analysis on the cavitation damage of the materials has been made from the determined impact load
distribution (e.g. impact load, bubble count) and erosion parameters (e.g. incubation period, MDPR).
According to Miner’s law, the exponents b of the F-N relation (Fb N = Constant) at the incubation
stage (N: the number of fracture cycle) were 5.62, 4.16, 6.25 and 8.1 for the 8.8Al-bronze,
flame-quenched sample, SUS316 and SR50A alloys, respectively. At steady-state, the exponents b
of the F-N curve (N: the number of cycles required for a 1μm increment of MDP) were
determined as 6.32, 5, 7.14 and 7.76 for the 8.8Al-bronze, flame-quenched sample, SUS316 and
SR50A alloys, respectively.
The Grain Boundary Embrittlement and De-Embrittlement Mechanism in Age Hardenable Fe-Ni-Ti Steels
Authors: Kim Min Saeng , Heo Yoon Uk , Lee Hu Chul
Published: March 2009

The strengthening and grain boundary embrittlement in an age hardenable Fe-20.4Ni-2.8Ti ternary alloy were investigated. The Vickers hardness and tensile properties were evaluated using a Vickers hardness and tensile tester and the precipitation behavior during aging treatment was observed by transmission electron microscopy (TEM). The fracture surface was observed using low voltage field emission scanning electron microscopy (FE-SEM). The alloy showed typical aging hardening curves with a single aging peak near 640 HV, but was found to undergo severe grain boundary embrittlement from the initial stages of aging treatment. Many fine particles were observed at the grain boundary fracture surface. These particles were identified as η-Ni3Ti precipitates nucleated at the prior austenite grain boundaries. When the aging time was extended, austenite nucleated at the interface of the matrix and η-Ni3Ti precipitate. With the formation of the austenite, the tensile ductility was recovered. It was concluded that the precipitation of the η-Ni3Ti intermetallic particles at the prior austenite grain boundaries and formation of the austenite are the main causes of embrittlement and subsequent de-embrittlement in aging of this alloy.
Microstructure and Mechanical Properties of the Wide-Gap Region Brazed with Various Powder Mixing Ratios of Additive to Filler Metal Powders
Authors: Kim Yong Hwan , Kwun S.I.
Published: March 2009

This study investigated the microstructure and mechanical properties of the wide-gap
region brazed with various powder mixing ratios of additive powder (IN738) to filler metal powder
(DF4B). The wide-gap brazing process was carried out in a vacuum of 2×10-5 torr at 1230°C for 1 hr.
The microstructure of the brazed region was analyzed by FESEM and AES. The wide-gap region
brazed with 60wt.% IN738 additive powder and 40 wt.% DF 4B filler metal powder had a
microstructure consisting of Ni solid solution + γ' and (Cr, W)2B. The fracture strength of the
wide-gap region brazed with 60 wt.% IN738 additive and 40 wt.% DF 4B powder was as high as 832
MPa at room temperature. It was found that the (Cr, W)2B and pores in the brazed region are
important microstructural factors affecting the mechanical properties of the wide-gap brazed region.
Phase Transitions in Binary SnO2-CeO2 System Prepared by a Sol-Gel Method
Authors: Tang Dian , Wang Xiao Kang , Zhang Teng
Published: March 2009

A differential thermal analyzer (DTA) and a X-ray diffractometer (XRD) were used to
study the solid transformations in binary SnO2-CeO2 oxide system. For 100wt% Sn and 100wt%Ce,
the transformations from amorphous xerogels to rutile and fluorite start from about 310 and 250°C,
respectively. The crystallizations to two-phase mixtures of rutile and fluorite take place at higher
temperatures. The two-phase mixtures appear in the region whose composition is between about
Sn-10wt%Ce and Sn-75wt%Ce. Sintered at 450°C for one hour, rutile phase dissolves about 10wt%
fluorite, and fluorite dissolves about 25wt% rutile. Precipitation reactions take place when the
sintering temperature is raised. The phenomenon that precipitation reactions are observed for rutile
and fluorite solid solutions means that lower temperature sintering produces solid solutions with
high supersaturation. In the as-sintered samples, the grain sizes are fine nano-crystals and the
complicated microstructures help the other cations to locate at discontinuous regions.
Microstructure and Mechanical Characteristic of Nano-WC Composite Coating Prepared by Laser Cladding
Authors: Wei Zhang , Hua Yeo Jian , Li Zhang Qun , Zhi Kong Fan
Published: March 2009

The experiments of laser cladding nanometer-size WC powder on 2Cr13 stainless steel
have been done using 7kW CO2 laser processing system. The microstructure and mechanical
characteristic of the WC composite coating were tested by scanning electronic microscope (SEM),
X-ray diffraction (XRD), energy dispersion analyzer of X-ray (EDAX) and microhardness tester.
The WC composite coating exhibits compact dendritic and reticular interdendritic structure. The
XRD data have revealed the phases of coating include Fe, WC, W2C and Fe3C. The nano-WC
composite coating has excellent mechanic performances. The surface hardness of composite coating
is about 1758HV0.2. Its abrasion proof is 3.5 times as high as that of parent metal.
Effect of High-Energy Ball-Milling and TiB2 Content on Microstructures and Properties of Cu-TiB2 Composites Sintered by SPS
Authors: Kwon Dae Hwan , Nguyen Thuy Dang , Choi Pyuck Pa , Kim Ji Soon , Kwon Young Soon
Published: March 2009

The microstructure and properties of Cu-TiB2 composites produced by high-energy
ball-milling of TiB2 powders and spark-plasma sintering (SPS) were investigated. TiB2 powders were
mechanically milled at a rotation speed of 1000rpm for short time in Ar atmosphere, using a planetary
ball mill. To produce Cu-xTiB2 composites( x = 2.5, 5, 7.5 and 10wt.% ), the raw and milled TiB2
powders were mixed with Cu powders by means of a turbular mixer, respectively. Sintering of mixed
powders was carried out in a SPS facility under vacuum.
High-energy ball-milling resulted in refinement of TiB2 particles. XRD patterns of milled TiB2
powders indicated broader TiB2 peaks with decreased intensities. After sintering at 950 for 5min
using the raw and milled TiB2 mixture powders, the sintered density decreased with increasing TiB2
content regardless of milling of TiB2. In the case of raw TiB2, hardness rapidly increased from 4 to 44
HRB with increasing TiB2 content. The electrical conductivity changed from 95.5 to 80.7 %IACS. For
mixtures of Cu powders with milled TiB2 powders, hardness increased from 38 to 67 HRB as TiB2
content increased, while the electrical conductivity varied from 88% to 51 % IACS. When compared
to compacts sintered with raw and milled TiB2 powders, the electrical conductivity of specimens with
raw TiB2 powder was higher than that of specimens with milled TiB2 powder, while hardness was
slightly lower.
Low Temperature Plasma Surface Alloying of Austenitic Stainless Steels
Authors: Sun Y. , Haruman E.
Published: March 2009

This paper gives a brief review on the three low temperature plasma surface alloying processes that have been developed in recent years to engineer the surfaces of austenitic stainless steels to achieve much enhanced surface hardness and wear resistance, without compromising their corrosion resistance. These include low temperature plasma nitriding, low temperature plasma carburizing and the newly developed hybrid process involving the simultaneous incorporation of nitrogen and carbon to form a dual layer structure. The processing, structural and property characteristics of each process are discussed briefly in this paper.
Effect of Deep Cryogenic Treatment on Carbide Precipitation and Mechanical Properties of Tool Steel
Authors: Rhyim Young Mok , Han Sang Ho , Na Young Sang , Lee Jong Hoon
Published: March 2009

It is well known that the durability of tool steel could be improved by deep cryogenic treatment. It has been assumed that the increase of service life of tool steel caused by decrease of retained austenite and/or by formation of nano-scale fine η-carbide. But the principles of deep cryogenic treatment remain unclear yet. In this research, to manifest the effect of deep cryogenic treatment on wear resistance, the specimen was emerged in liquid nitrogen for 20 hours for deep cryogenic treatment after austenitizing and the following tempering temperature was varied. The microstructure of specimens was observed using TEM and the mechanical properties and wear resistance were examined. As the tempering temperature increased, the carbides became larger and fine carbides were formed above certain temperature. In the case of deep cryogenic treated specimen, the number of carbides increased while the carbides size was decreased, furthermore, the fine carbide forming temperature was lowered also. It was considered that the deep cryogenic treatment increased the driving force for the nucleation of carbides. As tempering temperature increased, hardness decreased while wear resistance and impact energy increased. The deep cryogenic treated specimens showed this tendency more clearly. It was considered that the wear resistance is affected not only to the hardness but also to the precipitation of fine carbides, and this carbide evolution can be optimized through the deep cryogenic treatment.
Temperature Dependence of Pore Size Distribution of Highly Crystalline Titanosilicate MCM-41
Authors: Park Sung Soo , Park Dong Ho
Published: March 2009

High crystalline Ti-substituted MCM-41’s in the range of Si/Ti ≥ 30 were synthesized. We have carried out the controlling of the pore size of highly crystalline Ti-substituted MCM-41 simply by varying the synthesis temperature in 100-165 oC range. Depending on the reaction temperature, highly crystalline Ti-substituted MCM-41 with different d100 values in the range of 34.6-55.8 Å while using the same gel mixture (1.0 SiO2 : 0.27 CTABr : 0.19 TMAOH : 0.017 Ti(OEt)4 : 40 H2O) were synthesized. The pore size distribution, the surface area and the wall thickness for Ti-substituted MCM-41 samples by N2 adsorption method were 29.2-35.8 Å, 1140- 959 m2/g and 10.7-28.7 Å, respectively. Ti atoms substituted in MCM-41 were atomically dispersed in the framework of MCM-41, which was investigated by IR and UV/Vis spectrophotometer. The d100 values of Ti-MCM-41 samples of Si/Ti=30 under same reaction have a range of 39.2-53.5 Å.
Electrochemical Characteristics of Platinum Nanocluster Catalysts Using Oxyfluorinated Carbon Nanotubes Supports
Authors: Kim Seok , Cho Mi Hwa , Kwon Soo Han , Park Soo Jin
Published: March 2009

Multi-walled carbon nanotubes (MWNTs) were oxyfluorinated at several different
temperatures. The results indicated that graphitic carbon was the major carbon functional component
on the MWNT surfaces and other functional groups, such as C–O, C=O, HO–C=O, C–Fx, were also
present after oxyfluorination. The changes of surface properties of oxyfluorinated MWNTs were
investigated using FT-IR, EDS and XRD. From the surface analysis, it was found that surface
fluorine and oxygen contents increased with increasing oxyfluorination temperature and showed a
maximum value at 100 °C. Consequently, it was found that optimal treatment temperature was 100 °C
for the best electro activity of Pt/MWNT-100 catalyst and the oxyfluorinated Pt/MWNTs possessed
the better electrochemical properties than the pristine Pt/MWNTs.
Fabrication of High Density Y2O3 Ceramics by Magnetic Pulsed Compaction
Authors: Lee Jong Keuk , Hong Sung Jei , Lee Min Ku , Lee Jung G. , Rhee Chang Kyu , Jeong S.J. , Park J.S. , Park J.S.
Published: March 2009

Highly dense Y2O3 ceramics have been fabricated by a magnetic pulsed compaction
(MPC) which is capable of reaching a sufficiently high pressure (~1GPa) in a very short duration (a
few microseconds), and a subsequent pressureless sintering at 1600°C. The Y2O3 green bodies with
a relative density of about 68% were achieved by the application of the MPC process due to the
effect of an enhanced rearrangement and a high speed movement of the particles, without the help
of ceramic binder. Those compacts showed densities greater than 95%, which is very close to the
theoretical density, after the subsequent pressureless sintering process at 1600 oC. The shrinkage
rates of the diameter for the samples compacted by the MPC process were markedly reduced, when
compared to those for the ones by the conventional compaction (CC) process.
Photodefined Metal Pattern Formation and Its Electromagnetic Interference Shielding Effect
Authors: Hwang Eok Chae , Lee Ho Chul , Kim Jin Young , Cho Sung Hen , Noh Chang Ho , Song Ki Yong
Published: March 2009

This paper proposes a electromagnetic interference (EMI) shielding effect of Cu
mesh patterns which were formed by a novel, low-cost, photodefined metal pattern using a
bilayer thin film of amorphous titanium dioxide (TiO2) and hole-scavenger-containing
poly(vinyl alcohol) (PVA). Via UV-irradiation through a photomask on the bilayer film, the
photodefined image of photoelectrons can be easily produced, resulting in selective
palladium (Pd) catalyst deposition by reduction. In the bilayer thin film, the
hole-scavenger-containing PVA layer scavenge the holes in the valence band of
UV-irradiated TiO2 thin film, this retarding the recombination of the photoexcited
electron-hole pairs for a few minutes. These long-surviving photoelectrons in the bilayer
structure can reduce the Pd ions on only the photodefined region. Successive Ni electroless
plating on Pd catalysts and Cu electroplating on an electroless plated pattern are possible.
The electromagnetic interference shielding effects of selective nickel and copper mesh
patterns were investigated.
Developing Carbon Nanocomposite Smart Materials
Authors: Kang In Pil , Jung Joo Yung , Choi Gyeong Rak , Park Hyung Ki , Lee Jong Won , Yoon Kwang Joon , Yun Yeo Heung , Shanov Vesselin N. , Schulz Mark J.
Published: March 2009

To address the need for new smart materials, this paper explores the use of carbon
nanotubes to develop a nanocomposite smart material having electrochemical impedance properties
for sensing and actuation. Fabrication and characterization of the carbon nanocomposite material
are discussed in the paper. The issues related to hurdles in the practical manufacturing of
commodity level macro size nanocomposite smart materials with prescribed electrical and
electrochemical properties are also discussed.
Thermal and Mechanical Properties of Epoxy/Polyurethane Blend System Initiated by Cationic Latent Thermal Catalyst
Authors: Park Soo Jin , Seok Su Ja , Min Byung Gak
Published: March 2009

In this work, the blend of diglycidylether of bisphenol A (DGEBA) and modified
polyurethane (PU) was prepared and characterized the cure behavior and mechanical interfacial
properties. The N-benzylpyrazinium hexafluoroantimonate was used as a cationic initiator for cure,
and the content of PU was varied within 0~20 phr. The cure behavior and mechanical interfacial
properties were studied by DSC and the critical stress intensity actor (KIC) measurements. Also
thermal stabilities were carried out by TMA and TGA analyses. It is found that the cure activation
energy (Ea) was slightly increased on increasing the PU content, and a maximum value was noted at
10 phr PU. The mechanical interfacial properties measured from KIC showed a similar behavior with
the results of conversion. These results were probably due to the increase of the hydrogen bonding
between the hydroxyl groups of DGEBA and isocyanate groups in PU.
Preparation and Characterization of Bismuth Molybdate Catalyst for Oxidative Dehydrogenation of n-Butene into 1,3-Butadiene
Authors: Jung Ji Chul , Kim Hee Soo , Choi Ahn Seop , Chung Young Min , Kim Tae Jin , Lee Seong Jun , Oh Seung Hoon , Song In Kyu
Published: March 2009

α-Bi2Mo3O12 and γ-Bi2MoO6 catalysts were prepared by co-precipitation method, and they
were applied to the oxidative dehydrogenation of n-butene into 1,3-butadiene in a continuous flow
fixed-bed reactor. Formation of α-Bi2Mo3O12 and γ-Bi2MoO6 catalysts was well confirmed by XRD,
Raman spectroscopy, and ICP-AES analyses. The γ-Bi2MoO6 catalyst exhibited a better catalytic
performance than the α-Bi2Mo3O12 catalyst. Catalytic performance of γ-Bi2MoO6 strongly depended
on the pH value used in the co-precipitation step. It was also revealed that a mixed catalyst comprising
γ-Bi2MoO6 (90 wt%) and small amount of α-Bi2Mo3O12 (10 wt%) showed the best catalytic
performance due to the synergy effect of two components. It is believed that the high catalytic
performance of the mixed catalyst resulted from high diffusion coefficient of lattice oxygen in the
γ-Bi2MoO6 and from abundant chemisorption sites for n-butene in the α-Bi2Mo3O12.
Synthesis Of Ti50Ni50 Alloy Nanopowders Synthesized by Modified Levitational Gas Condensation Method
Authors: Han Byung Sun , Uhm Young Rang , Lee Min Ku , Park Jin Ju , Rhee Chang Kyu , Kim G.M.
Published: March 2009

The stoichiometric Ti50Ni50 alloy nanopowders were synthesized by levitational gas
condensation (LGC) using micron powder feeding system and their particulate properties were
investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-
-Emmett-Teller (BET) method. The starting Ti and Ni micron powders ∼ 150μm were incorporated
into the micron powder feeding system. The ingot type of Ti-Ni alloy was used as a seed material for
levitation and evaporation reactions. The collected powders were finally passivated by oxidation. The
x-ray diffraction experiments have shown that the synthesized powders were completely alloyed with
50Ti and 50Ni in at.% and comprised of two different cubic and monoclinic crystalline phases. The
TEM results showed that the produced powders were a very fine and uniform with the spherical
particle size of 18 to 32 nm. The typical thickness of passivated oxide layer on the particle surface
was about 2 to 3 nm. The specific surface area of the Ti-Ni alloy nanopowders was 54.8 m2/g based
on a BET method.
The Effect of Powder Size on Thermoelectric Properties of 95%Bi2Te3-5%Bi2Se3 Alloy
Authors: Hong Soon Jik , Hwang K.S. , Byeon Jai Won , Lee Min Ku , Rhee Chang Kyu , Chun Byong Sun
Published: March 2009

The n-type (95%Bi2Te3- 5%Bi2Se3) compound was newly fabricated by gas atomization
and hot extrusion, which is considered to be a mass production technique of this alloy. The effect of
powder size on thermoelectric properties of 0.04% SbI3 doped 95%Bi2Te3- 5%Bi2Se3 alloy were
investigated. Seebeck coefficient (α) and Electrical resistivity (ρ) increased with increasing powder
size due to the decrease in carrier concentration by oxygen content. With increasing powder size,
the compressive strength of 95%Bi2Te3-5%Bi2Se3 alloy was increased due to the relative high
density. The compound with ~300 μm size shows the highest power factor among the four different
powder sizes. The rapidly solidified and hot extruded compound using 200~300 μm powder size
shows the highest compressive strength.
Grain Refinement of 6061 Al Alloy by the Modified Strain-Induced Melt- Activated(SIMA) Process for Semi-Solid Processing
Authors: Song Young Buem , Hong Chun Pyo
Published: March 2009

The dynamic process of fine grain evolution of 6061 aluminum alloy during modified strain-induced, melt-activated (SIMA) process was studied. The modified SIMA process employed casting, two stage homogenization, warm multi-forging, and recrystallization and partial melting (RAP). Multi-forging was carried out at a strain rate of 9x10-3 s-1 to accumulate high strains, with decreasing temperature from 250 to 200 °C. The alloy multi-forged with the accumulated strain of about 12 and RAP at 640 °C for 10 min exhibited the uniform equiaxed recrystallized grain structure. Accordingly, it was evident that multi-forging was very effective on grain refinement and grain size uniformity. The present modified SIMA process was discussed as an alternative thermo-mechanical processing for preparing the alloys with fine grained structure for semi solid processing.
Comparison Studies on Nitrile-Butadiene Rubber Nanocomposites Depending on the Organically Modified Montmorillonites
Authors: Mang Ji Young , Choi Dong Hoon , Han Mi Jeong
Published: March 2009

A various organic modifiers depending on the substituents of ammonium ions were
synthesized and used to prepare organically modified montmorillonite (OMMT). Nitrile-butadiene
rubber (NBR)/OMMT nanocomposites could be obtained using melt-compounding followed by
hot-press vulcanization. d-Spacings of OMMT were changed as the chemical structures of
modifiers were varied. X-ray diffraction (XRD) and tensile measurements of NBR nanocomposites
revealed that the structures of organic modifiers affect the properties of NBR nanocomposites after
vulcanization. Long alkyl chain of OMMT induced higher interaction between NBR and OMMT,
resulting in higher tensile strength, Young’s modulus, and hardness of NBR/OMMT
nanocomposites.
Radiation Effect on Poly(ε-Caprolactone) Nanofibrous Scaffold
Authors: Lim Youn Mook , Jeun Joon Pyo , Jung Chan Hee , Choi Jae Hak , Kang Phil Hyun , Nho Young Chang
Published: March 2009

Nano- to micro-structured biodegradable poly(ε-caprolactone) nanofibrous scaffolds
(PCL NFSs) were prepared by an electrospinning. Electrospinning has recently emerged as a
leading technique for generating the biomimetic scaffolds for tissue engineering applications. The
average diameter of the electrospun PCL NFSs ranged from 0.5 to 2 ㎛ depending on the
solvent/nonsolvent mixture. PCL NFSs were irradiated using γ-ray and their mechanical properties
and biodegradability were measured. In vitro/vivo degradation studies of the scaffolds as a function
of the radiation dose were performed. The scaffolds were degraded more slowly in vitro than in vivo.
The Study of Fatigue Crack Growth of 304SS with the Influence of Loading Frequency and Temperature
Authors: Chen Jien Jong , Shih Yan Shin
Published: March 2009

James performed a series of experimental study on austenitic stainless steels and
suggested an equation for assessing the influences of temperature, stress ratio and loading frequency
on the fatigue crack growth rate. Authors have studied the effect of either loading frequency alone
or of temperature alone on the fatigue crack growth rate by employing the mechanical behaviors of
material. In this study, the mechanical behaviors of material are employed for evaluating the
combined effect of loading frequency and temperature. Using the derived dimensionless functions
of yielding stresses and Young’s modulus, the equation represented the combined effect of loading
frequency and temperature on fatigue crack growth rate of 304SS was proposed.
Enhancement of Flaw Detectability Using Time Reversal Techniques
Authors: Kim Hak Joon , Thompson R. Bruce , Song Sung Jin
Published: March 2009

Ultrasonic phased array inspection has been paid a great attention in ultrasonic
nondestructive evaluation since it can provide a benefit of focusing and/or steering ultrasonic
beams. A time reversal technique is claimed to be very robust to focus beams through
inhomogeneous media, using the phased array transducers. In this paper, the performance and
limitations of a D.O.R.T. method, which is one of the time reversal techniques, is considered based
on the experimental studies. In addition, a variation of the D.O.R.T, namely a pre-focused
D.O.R.T., is proposed in order to overcome the limitations of the current D.O.R.T. method. The
results of the newly proposed method are compared to those obtained by conventional focusing
methods.
Studies on a High-Temperature Air Combustion Burner for a Compact Fuel-Cell Reformer
Authors: Lee K.H. , Kwon Oh Chae
Published: March 2009

A new burner configuration for a compact fuel-cell reformer with a high-temperature air combustion concept was studied. The burner was computationally designed for a 40 Nm3/hr hydrogen-generating reformer using natural gas-steam reforming method. In order to satisfy the primary requirements for designing a reformer burner (uniform distribution of temperature along the fuel processor walls and minimum heat losses from the reformer), the features of the present burner configuration included 1) a self-regenerative burner for an exhaust-gas-recirculation to apply for the high-temperature air combustion concept, and 2) an annular-type shield for protecting direct contact of flame with the processor walls. For the present design conditions, the predicted temperature distributions along the processor walls were found uniform within 100 K variation. Thus, the present burner configuration satisfied the requirement for reducing temperature gradients along the processor walls, and consequently demonstrated that the high-temperature air combustion concept could be applied to the practical fuel reformers for use of fuel cells. The predicted uniform temperature distributions along the processor walls were experimentally demonstrated for a test burner.
Analysis of Thermal Stress and Flow Characteristics in a Bellows-Seal Valve for the Reliability Establishment
Authors: Kim Kwang Su , Kim Hun Mo , Kim Youn Jea
Published: March 2009

Because of design and manufacturing costs, it is important to predict an expected life of
bellows with component stresses of bellows as its design factors and material characteristics. Besides,
if the reliability of the bellows in a bellows-seal valve is not properly assessed, leakage would be
occurred easily before the expected life of the bellows. In this study, numerical analyses are carried
out to elucidate the thermal and flow characteristics with bellows-seal globe valve for high
temperature and for high pressure conditions using FSI (Fluid-Structural Interaction) technique.
Thermal stress affecting bellows life is depicted with its axial displacement to assess the reliability of
the bellows. In addition, we made a basic fuzzy algorithm to add new design parameter. As the result
of this study, we got the reasonable coefficients for valve and thermal stress for bellows, compared
with existing coefficients and calculated values. Also, since the maximum thermal stress of the
bellows is below a general yield stress of used material, the reliability of the bellows is established.
Enhanced Reliability of Mold Close and Open Control in Injection Molding Machine through Fuzzy Algorithm
Authors: Park Jin Hyun , Kim Hun Mo
Published: March 2009

Injection Molding Machine (IMM) has been widely used for the mass production of a
plastic product. With the development of the relative technique, various injection molding
techniques have been developed and we could get more precise plastic product. In this paper, we
present the system reliability of an IMM subject to a controller. The controller of an IMM is an
important factor in the injection molding and this controller has direct influence on the quality of a
plastic product. Presently, the mold close and open control method of a toggle type IMM is openloop
control. Open-loop method is difficult to control when they affect highly nonlinear
characteristic in an IMM. Therefore, we propose an alternate approach to implement the controller
using closed-loop control method to enhance the reliability. Through the development, fuzzy
control algorithm is selected and it is programmed by an IL(Instruction List) and a LD(Ladder
Diagram) on a PC based PLC. For the development of an IMM controller, PC based PLC of PCI
card type, distributed I/O modules with CANopen, Industrial PC and HMI(Human Machine
Interface) software are used.
A Carbon Nanotube Smart Material for Structural Health Monitoring
Authors: Kang In Pil , Schulz Mark J. , Lee Jong Won , Choi Gyeong Rak , Jung Joo Yung , Choi Jae Boong , Hwang Sung Ho
Published: March 2009

This study introduces a nano smart material to develop a novel sensor for Structural Health Monitoring (SHM) of mechanical and civil systems. Mechanical, civil, and environmental systems need to become self-sensing and intelligent to preserve their integrity, optimize their performance, and provide continuous safety for the users and operators. Present smart materials and structures have fundamental limitations in their sensitivity, size, cost, ruggedness, and weight. Smart materials developed using nanotechnology have the potential to improve the way we generate and measure motion in devices from the nano to the macro scale in size. Among several possible smart nanoscale materials, Carbon Nanotubes (CNT) have aroused great interest in the research community because of their remarkable mechanical, electrochemical, piezoresistive, and other physical properties. To address the need for new intelligent sensing based on CNT, this study presents piezoresistivity and electrochemical properties and preliminary experiments that can be applied for SHM. This study is anticipated to develop a new multifunctional sensor which can simultaneously monitor strain, stress and corrosion on a structure with a simple electric circuit.
Failure Probability Estimation of Pressure Tube Using Failure Assessment Diagram
Authors: Lee Joon Seong , Kwak Sang Log , Pyo Chang Ryul
Published: March 2009

Pressure tubes are major component of nuclear reactor, but only selected samples are
periodically examined due to numerous numbers of tubes. Pressure tube material gradually pick up
deuterium, as such are susceptible to a crack initiation and propagation process called delayed hydride
cracking (DHC), which is the characteristic of pressure tube integrity evaluation. If cracks are not
detected, such a cracking mechanism could lead to unstable rupture of the pressure tube. Up to this
time, integrity evaluations are performed using conventional deterministic approaches. So it is
expected that the results obtained are too conservative to perform a rational evaluation of lifetime. In
this respect, a probabilistic safety assessment method is more appropriate for the assessment of
overall pressure tube safety. This paper describes failure probability estimation of the pressure tubes
using probabilistic fracture mechanics. Failure assessment diagram (FAD) of pressure tube material is
proposed and applied in the probabilistic analysis. In all the analyses, failure probabilities are
calculated using the Monte Carlo simulation. As a result of analysis, failure probabilities for various
conditions are calculated, and examined application of FAD and LBB concept.
Microstructure and Magnetic Properties of Nd4.5Fe(76.5-x)B18.5Cu0.5Zrx Nanocomposite Permanent Magnetic Alloys
Authors: Qiao Y. , Zhang Mao Cai , Zhu J.
Published: March 2009

Nanocomposite Nd2Fe14B/Fe3B magnetic materials with high performance have been obtained by
crystallizing over-quenched ribbons. The effect of addition element of Cu and Zr on the phase
component, microstructure and magnetic properties of Nd4.5Fe（76.5-x）B18.5Cu0.5Zrx (x= 0.4, 0.5, 1.5, 2.0,
3.0, 4.0) has been systematically investigated. The average grain size of Nd2Fe14B phase and Fe3B
phase for the different compositions were calculated from X-day diffraction pattern, which are in
accordance with TEM micrographs. For the Nd4.5Fe77B18.5 ribbons, the average grain size of Nd2Fe14B
and Fe3B were 34.2 nm and 51.7 nm, and for the Nd4.5Fe76.3B18.5Cu0.5Zr0.4 ribbons, they were only 36.5
nm and 37.1 nm, respectively. It has been found that the additions of Cu and Zr cause the reduction of
the difference of grain size between the hard magnetic phase and the soft magnetic phase, that increase
the exchange coupling between them. Therefore, it would lead to the magnetic properties improvement.
It has been determined that Nd4.5Fe76.3B18.5Cu0.5Zr0.4 was the optimal composition, and the optimal
magnetic properties were: Br= 1.204 T, Hci= 271 kA/m, and (BH)max =111.2 kJ/m3.
Size Effect on Glass Transition Temperature of Nanopolymers
Authors: Lang X.Y. , Jiang Qing
Published: March 2009

A unified model is developed for the finite size effect on the glass transition temperature of
polymers Tg(D) where D denotes diameter of particles or thickness of films. In terms of this model,
Tg(D) depends on both the size and interface conditions. The predicated results are consistent with the
experimental evidences of polystyrene (PS) and poly (methyl methacrylate) (PMMA) films and
nanoparticles with different interface situations.
Interlaminar Fracture of CF/EP Composites Modified with Nano-Silica
Authors: Deng Shi Qiang , Rosso P. , Ye Lin , Friedrich Klaus
Published: March 2009

Fracture toughness and other mechanical properties of epoxies modified with nano-slica
particles were measured to elaborate effects of nano-additives on fracture behaviour of the modified
epoxies. Interlaminar fracture behaviours of the nano-silica modified CF/EP composites were
subsequently investigated by conducting Mode-I and Mode-II interlaminar fracture toughness tests as
well as transverse tension tests. It was found that the fracture toughness of the nano-silica modified
epoxies and the interlaminar fracture toughness of nano-silica modified CF/EP composites have been
increased significantly (>50%), while the strength and modulus of the materials remain unchanged or
slightly higher. In particular, the nano-silica modified epoxies showed only very little reduction in the
glass transition temperature (Tg).
Synthesis and Characterization of Nanocrystalline TiO2 Doped with 2 at.% Sc3+ and V5+ Ions
Authors: Zhang Dong Ri , Kang Young Soo
Published: March 2009

Nanoparticles of anatase TiO2 doped with 2 at.% Sc3+ and 2 at.% V5+ ions were
synthesized by sol-gel method. Average crystal sizes of TiO2, TiO2+2 at.% Sc, TiO2+2 at.% V and
TiO2+2 at.% (Sc+V) calculated from XRD patterns are 18.0, 16.9, 18.0, 16.2 nm, respectively.
HRTEM images of TiO2 and TiO2+2 at.% (Sc+V) exhibit well-defined lattice fringe. The lattice
spacings of TiO2 and TiO2+2 at.% (Sc+V) are both measured to be 3.3 Å, which correspond to the
distance between the (101) planes of anatase TiO2. Raman spectra of the samples demonstrate the
well dispersion of Sc3+ and V5+ ions in the TiO2 matrix. UV-vis diffuse reflectance absorption spectra
of the samples show the characteristics of TiO2, and the diffuse reflectance spectra of TiO2+2 at.% V
and TiO2+2 at.% (Sc+V) exhibit red shifts and weak wide absorptions in the visible region of
400-600 nm.
A Direct Route to Active Silica Nanoparticles
Authors: Chen X.Q. , Liu Y.Y. , Qi K.H. , Zhou X. , Xin J.H.
Published: March 2009

Monodisperse silica particles containing available active C=C bonds were directly
prepared by a simple two-step sol-gel method. In the first step the hydrolysis of
vinyltrimethoxysilane (VTMS) was performed under acidic conditions in an aqueous solution. In
the second step the condensation of the siloxane precursors progressed under basic conditions,
resulting in production of silica nanoparticles containing available active C=C bonds. The products
were characterized using SEM and FTIR.
Preparation and Reactivity Test of Nano Size ZnO for Removal of H2S and COS in a Gasified Fuel Gas
Authors: Park No Kuk , Lee Yu Jin , Han Gi Bo , Ryu Si Ok , Lee Tae Jin
Published: March 2009

A nano-size zinc oxide was formulated for the effective removal of a very low
concentration of sulfur compounds (H2S, COS) contained in a gasified fuel gas and their reactivity
was also investigated in this study. They were prepared by a matrix-assisted method with various
precursors. An active carbon was used for a matrix and zinc nitrate, zinc chloride, and zinc sulfate
were selected as precursors. Zinc nitrate was the best precursor for the formulation of the nano-size
zinc oxide in the experiments. The size of the formulated nano-size zinc oxides was in the range of
20-30 nm and its surface area was about 56.2 m2/g. From TGA(thermal gravity analysis) test, it was
found that its sulfur capacity was about 5.83 gS/100 g-sorbent and sulfur absorption rate was about
0.363 gS/min·100 g-sorbent. Their reactivity increased with the smaller size and the larger surface
area of the sorbents. Most prepared nano-size zinc oxides showed an excellent performance for the
removal of not only H2S but also COS. Their absorption rate was faster than commercial zinc oxides.
In order to investigate the sulfur absorption characteristics of zinc oxide, a experiments for the
nano-size zinc oxides formulated from zinc nitrate precursors were carried out in a packed-bed reactor
system over the temperature of 500 . It was concluded that the zinc oxide prepared by zinc nitrate as
a precursor showed the highest sulfur removing capacity.
The Influence of Polymer Content on Electrochemical Properties of Si Electrode
Authors: Choi Young Jin , Shin Dong Hyun , Kim Sung Hyun , Park Sang Choul , Cho Gyu Bong , Kim Ki Won
Published: March 2009

Si electrode with different amount of polymer binder was fabricated by ball milling. With
increasing of polymer content, not only porosity but also the first charge capacity of Si electrode was
increased. The Si electrode enhanced electrical conductivity showed high first capacity of 3644mAh/g
and improved cycle performance. Si electrode having good electrochemical property could be
fabricated by controlling amount of polymer.
Electrochemical Properties of Al Doped Li(Ni1/3Co1/3Mn1/3)O2
Authors: Kim Seon Hye , Shim Kwang Bo , Han Kyoung Ran , Kim Chang Sam
Published: March 2009

Al doped Li(Ni1/3Co1/3Mn1/3-xAlx)O2 (x=0.005, 0.01, 0.05) and
Li(Ni1/3-x/2Co1/3Mn1/3-x/2Alx)O2 (x=0.01, 0.05) cathode materials for lithium ion batteries were
synthesized using an ultrasonic spray pyrolysis and heat treatment. The substitution with Al reduced
the content of Mn3+, promoted grain growth, and broadened the particle size distribution of
synthesized powders. The initial discharge capacity of cells made with 0.5 mol% Al doped
Li(Ni1/3Co1/3Mn1/3-0.005Al0.005)O2 powder was as high as that of the undoped (~180 mAhg-1, 3.04.5
V), and showed an excellent cycle stability. The improvement of the cycle stability was considered to
be due to the decrease of Mn3+ in Li(Co1/3Ni1/3Mn1/3-xAlx)O2 by Al doping.
Ag Deposition on Si-C Composite Anodes for Lithium Ion Batteries
Authors: Song Jun Hye , Han Won Kyu , Sun Yang Kook , Kang Sung Goon
Published: March 2009

Ag deposited Si/C composite was studied as the anode. In order to enhance the
electrochemical properties of Si electrodes, which show poor cyclability as an anode in lithium ion
secondary battery, the deposition of Ag prepared by electroless deposition method on the surface of
the Si/C composite powder produced by high energy ball milling. Si/C composite shows overall fade
in capacity which is caused by Si pulverization. However, The Ag deposited Si/C composite improves
cyclability and exhibits capacity of ~590mAh/g after 30th cycle. Scanning electron microscopy(SEM)
and X-ray diffraction(XRD) measurement are adapted to inspect the deposition process.
The Effect of Oxygen Pressure on the Synthesis of LiNiO2
Authors: Kim B.H. , Kim J.H. , Song M.Y. , Ida Takashi , Ishizawa N.
Published: March 2009

To investigate the effect of oxygen pressure on the synthesis of LiNiO2 cathode material
for Li secondary battery, powder was prepared by emulsion method and calcined at 750°C for 24 h
under various oxygen gas pressures. LiNiO2 single phase could be synthesized under oxygen
pressure of 101.3~103.3 kPa but not under air atmosphere. Cation mixing in Li site of LiNiO2
lowered as oxygen pressure increased and was saturated around 103.3 kPa. The lowest cation
mixing, 7.0% of Ni3+ in the Li site was obtained at 750°C for 24 h under 103.3 kPa of oxygen
pressure.
The Effect of SnOx as the Protective Layer for the Lithium Manganese Oxide Thin Film
Authors: Moon Hee Soo , Yang Jae Hun , Lee Jae Ho , Ahn Seung Ho , Park Jong Wan
Published: March 2009

Lithium manganese oxide (LiMn2O4) had been a promising material for lithium-ion and
thin film batteries. However, the LiMn2O4 had some problems such as the manganese dissolution into
liquid electrolyte. In order to improve cycleability, we introduced SnOx layer as protective layer. This
layer was deposited on spinel LiMn2O4 by using radio frequency magnetron sputtering. The deposited
SnOx layer fully covered the LiMn2O4 , and didn’t make a change the crystallinity of the spinel films.
The SnOx layer prevented direct contact of liquid electrolyte and improved the cycle retention.
Improvement of the Reverse Characteristics of Ti/4H-SiC Schottky Barrier Diodes by Thermal Treatments
Authors: Kim Dae Hwan , Lee Jong Ho , Moon Jeong Hyun , Oh Myong Suk , Song Ho Keun , Yim Jeong Hyuk , Lee Jae Bin , Kim Hyeong Joon
Published: March 2009

Ti/4H-SiC Schottky barrier diodes were fabricated under 500, 750, 1000 °C thermal
treatment conditions. After the heat treatment at 750 °C, formation of TiC(111) and Ti5Si3(210)
phases was confirmed by XRD analysis. Formation of Ti carbide and silicide phase increased
breakdown voltage VB from 545 V to 830 V. An improvement of breakdown voltage (VB) was
observed in case of the thermal treatment in nitrogen ambient at 750 °C for 2 min. Ideality factor (n),
specific on resistance (Ron), and Schottky barrier height (Φb) were 1.04, 2.7 m-cm2, 1.33 eV
respectively.
Synthesis of Nanosized TiO2-Ag-SiO2 Sols by Modified Sol-Gel Method and their Application for Methane Hydrate Formation
Authors: Lee Ju Dong , Kim Hyoung Chan , Kim Young Seok , Kim Yang Do , Lee Man Sig
Published: March 2009

Nanosized TiO2-Ag-SiO2 sols were prepared with modified sol-gel method using reduction
agent. The physical properties of the prepared particles were investigated by TEM, XRD and FT-IR.
The titanium tetraisopropoxide (TTIP, 98% Aldrich), teraethylorthosilicate (TEOS, 98% Aldrich) and
silver nitrate were used as precursors of titania, silica and silver, respectively. Sodium citrate tribasic
dihydrate (C6H5Na3.2H2O, Aldrich) was used as a reduction agent. This paper presents the effect of
nanosized TiO2-Ag-SiO2 sols on the formation of methane hydrate in a semi-batch vessel. The
micrographs of TEM showed that the TiO2-Ag-SiO2 particles possessed a spherical morphology with
a narrow size distribution. The crystallite size of particles decreased with an increasing the SiO2
content. In addition, the water solution with 1.0 wt% of TiO2-Ag-SiO2 particles acted as promoter for
methane hydrate formation.
The Reinforcement Destruction Simulation of an Al-Zn Carbon Fibers Composite
Authors: Cobzaru Petru , Nedelcu Dumitru
Published: March 2009

The destruction of the Carbon fibers reinforcement occurs during an infiltration with
metallic matrix, under well-defined technological circumstances. The Al carbide resulted plays an
important role in transferring the efforts trough the interface as long as it doesn’t significantly reduce
the diameter of the carbon fibers. The interface reaction can be controlled by adding K2ZnF6 and Zn,
thus improving the wetting of the reinforcement and reducing the Al reactivity against carbon. This
article deals with a simulation using specific technological parameters in order to achieve an
evolution of the Al carbide thickness of the layer, when Zn percentages of the Al matrix change.
Fabrication of SiCf/SiC Composite by the PIP Process with Electron Beam Curing Method
Authors: Park Ji Yeon , Woo Chang Hyun , Kim Weon Ju , Ryu Woo Seog
Published: March 2009

In the polymer impregnation and pyrolysis (PIP) process for the fabrication of SiCf/SiC
composite, the curing process should be included to increase the conversion yields. During the curing
process, unintended oxygen is introduced. Control of this oxygen is very important to obtain
composites with a good high temperature stability. Using the electron beam curing process with full
doses of 2~10 MGy and the pyrolysis process at 1300~1500oC, composites with an oxygen contents
of less than 1 wt% could be obtained.
Fabrication of Polymer Nanotubes Using Alumina Template
Authors: Oh Han Jun , Jeong Yong Soo , Kwon So Hyun , Heo Chang Hoe , Ki Beom Su , Chi Choong Soo
Published: March 2009

The polymer nanotube and nanorod of polystyrene (PS) and polymethyl methacrylate
(PMMA) respectively hav been synthesized by wetting process, using nanoscale AAO templates. For
the AAO template formed in phosphoric acid, which has the pore diameters between 200 and 300 nm,
the polymer nanotubes can be obtained. However, for the AAO template formed in oxalic acid with
the pore diameters between 60 and 70 nm, polymer nanorods are obtained due to a complete filling of
the pore space instead of pore wall wetting of polymer. It is indicated that the wetting behavior of
polymer on the AAO template play an important role in synthesis of polymer nanotubes, and the
shape and length can be controlled by anodic time for AAO template fabrication.
Synthesis of Polymer/Silica Hybrid Nanocomposites Prepared by the Sol-Gel Method
Authors: Kim Ji Kyung , Park Seong Soo , Ryu Bong Ki , Park Hong Chae , Yoon Seog Young
Published: March 2009

The organic-inorganic hybrid nanocomposites were successfully obtained by the sol-gel
process with tetraethylorthosilicate (TEOS) as an inorganic networking precursor and
2-hydroxyethylmethacrylate (HEMA) as the nonsurfactant template in the presence of benzil initiator.
The characteristics of the obtained hybrid were examined by means of TGA, FTIR, SEM, and TEM.
The synthesized HEMA/SiO2 hybrid was nearly transparent, monolithic, and monodispersed with the
average size of 25 nm. It was found that the hybrid structure could be defined by intertwining organic
and inorganic polymeric networks.
The Improvement of Chemical and Mechanical Properties of Al/Cu-Coated SiC Composites
Authors: Kang Min , Park Eun Duck , Yie Jae Eui
Published: March 2009

The effect of a microwave-enhanced wet chemical etching process of SiC particles on the
electroless copper plating and on the Al/Cu-coated SiC composites was investigated. The
microwave-enhanced wet etching process increased the concentration of surface oxides on SiC. The
BET surface area of SiC increased, reached its maximum value at 30 s, and then decreased during an
etching process. The enhanced chemical adhesion strength between the coated copper and SiC was
observed after an etching process. Furthermore, the sintering density and transverse rupture strength
(TRS) of Al/Cu-coated SiC composites were improved when SiC particles were etched. This result
indicated that the microwave-enhanced etching of SiC particles also improved chemical and
mechanical adhesion of Al/Cu-coated SiC composites.
One Step Synthesis and Consolidation of Nanostructured ZrSi2-SiC Composite and its Mechanical Properties
Authors: Shon In Jin , Park Hyun Kuk , Ko In Yong , Yoon Jin Kook , Hong Kyung Tae
Published: March 2009

Dense nanostructured ZrSi2-SiC composite was synthesized by high frequency induction
heated combustion synthesis (HFIHCS) method within 1 minute in one step from powders of ZrC
and 3Si. Simultaneous combustion synthesis and densification were accomplished under the
combined effects of an induced current and mechanical pressure. Highly dense ZrSi2-SiC with
relative density of up to 98% were produced under simultaneous application of a 60MPa pressure
and the induced current. The average grain size and mechanical properties (hardness and fracture
toughness) of the composite were investigated.
Mechanical Properties and Consolidation of WC-8wt.%Ni Hard Materials by HFIHS and PCAS
Authors: Jeong In Kyoon , Kim Hwan Cheol , Doh Jung Mann , Yoon Jin Kook , Ko In Yong , Shon In Jin
Published: March 2009

Two methods, High-Frequency Induction-Heated Sintering (HFIHS) and Pulsed Current
Activated Sintering (PCAS), were utilized to consolidate WC-8wt.%Ni hard materials. The
demonstrated advantages of these processes are rapid densification to near theoretical density in a
relatively short time and with insignificant change in grain size. The hardness, fracture toughness, and
the relative density of the dense WC–8Ni composites produced by HFIHS and PCAS were
investigated. And the effect of variation in particle size of WC powder on the sintering behavior and
mechanical properties were investigated.