bluuebunny/crossref_metadata_2025 huggingface dataset:
Adhesion Properties of Copper/Polyimide Film Modified by Reactive Ion Etching(RIE)
Authors: Lee W.J. , Kim Yoon B. , Lee W.Y. , Han S.H. , Han J.H. , Jee K.K.
Published: March 2009

Surface modification of polyimide(PI) films was treated with oxygen RIE by varying ion doses
from 1x1016 to 1x1018 ions/cm2 at an ion beam energy of 250 eV. Following the modification of PI
surface, metal films consisting of NiCr/Cu and Cu were deposited on modified PI films by D.C.
magnetron sputtering and electroplating, respectively. The surface modified PI film was
characterized by XPS, AFM, SEM and contact angle measurement, respectively. The water contact
angle of PI film decreased significantly from 64° to 4.4° with an increase of ion dose, indicating
that the surface energy of PI film increased. The XPS spectrum showed that functional group,
particularly C-O bonding, on modified PI surface was significantly increased by interaction
between scissored unstable chains and reactive ions. The modified PI film surfaces by oxygen RIE
showed significant improvement in adhesion to a overcoated metal film of NiCr/Cu.
Impact and Indentation Resistance of Superhard AlCrN Thin Films
Authors: Lee Sang Yul
Published: March 2009

Binary transition metal nitride films have excellent tribological properties but these binary
systems are still inadequate for high temperature applications due to their low oxidation temperature.
Above 700°C, formation of porous oxides at the film surface deteriorates their mechanical properties
rapidly by the. Especially impact and indentation resistance of these films deteriorate very quickly. In
order to overcome these problems, Al based Al1-xCrxN films with X=0.29 and X=0.69 were
synthesized by closed field unbalanced magnetron sputtering with vertical magnetron sources and
their chemical composition, crystalline structure, morphology and mechanical properties including
impact and indentation resistance were investigated. Synthesized Al1-xCrxN films formed solid
solution showing FCC B1 type structure with strong (111) preferential orientation and films with
X=0.29 showed a superhard hardness value of approximately 41GPa while films with X=0.69 did
approximately 31GPa. While there was insignificant difference between Al1-xCrxN films with X=0.29
and X=0.69 in terms of Rockwell C indentation resistance, much improved impact resistance could be
observed from the Al1-xCrxN films with X=0.29.
The Effects of Si and Deformation on the Phase Transformation in Dual Phase Steels
Authors: Lee Sang Hwan , Choi Jong Min , Cho Yeol Rae , Lee Kyung Jong
Published: March 2009

The effect of Si on phase transformation was well known in dual phase steels. Si promoted
the ferrite transformation and the enriched C in untransformed austenite prohibited the transformation
at intermediate temperature range resulting in the formation of lower bainite and martensite at low
temperature range. In addition, during continuous cooling with fast cooling rate, it was very hard to
differentiate one phase from the others. In order to clarify the effects of Si on the austenite-to-ferrite
transformation quantitatively, the start temperatures of bainite(BS) and martensite(MS) as well as
ferrite(Ae3) and pearlite(Ae1) were calculated by thermodynamic analysis. LVDT measured by
dilatometer and 1st differentiation peaks of LVDT were examined with microstructures, which gives a
possibility of the phase separation. In CCT diagrams, it was also found that large austenite grain
size(AGS) widened the gap between the transformation start(Ts) and end(Tf) when Si was added.
A Method for the Evaluation of Heat Transfer Coefficient by Optimization Algorithm
Authors: Kim Jeong Tae , Lim Chae Ho , Choi Jeong Kil , Lee Young-Kook
Published: March 2009

New method for evaluation of heat transfer coefficient is proposed. In general, many
researchers have been studied about inverse problem in order to calculate the heat transfer coefficient
on three-dimensional heat conduction problem. But they can get the time-dependent heat transfer
coefficient only through inverse problem. In order to acquire temperature-dependent heat transfer
coefficient, it requires much time for numerous repetitive calculation and inconvenient manual
modification. In order to solve these problems, we are using the SQP(Sequential Quadratic
Programming) as an optimization algorithm. When the temperature history is given by experiment,
the optimization algorithm can evaluate the temperature-dependent heat transfer coefficient with
automatic repetitive calculation until difference between calculated temperature history and
experimental ones is minimized. Finally, temperature-dependent heat transfer coefficient evaluated
by developed program can used on the real heat treatment process of casting product.
Cooling and Heating Characteristics of Ti-Ni Based Shape Memory Alloy Wire Actuators
Authors: Nam Jung Min , Lee Jae Hwa , Lee Yun Jung , Nam Tae Hyun
Published: March 2009

Ti-51Ni(at%) and Ti-40Ni-10Cu(at%) alloy wires with diameters of 0.3mm, 0.5mm and
0.7mm were prepared by drawing the alloy ingots fabricated by vacuum induction melting. Heating
rates of the wires were investigated by measuring changes in temperatures of them while applying
currents in the range of 1 A and 6 A to them and cooling rates were investigated by measuring changes
in temperatures of them after cutting currents. Heating rate increased with increasing the amount of
current, while cooling rate was kept constant. Both heating rate and cooling rate increased with
decreasing diameter of wire. This suggested that high amount of current and small wire diameter
were required for high heating and cooling rate. Comparing Ti-50Ni alloy wires with Ti-40Ni-10Cu
alloy wires, heating rates of the latter was faster than that of the former, although cooling rates were
almost same. This suggested that Ti-40Ni-10Cu alloy wires is better than Ti-50Ni alloy wires for the
applications requiring high actuating rates.
Encapsulation of H2 Molecules in Cs3Na9-A Zeolite: A Theoretical Approach
Authors: Song Mee Kyung , Kim Jung Sup , No Kyoung Tai
Published: March 2009

A theoretical method to study the encapsulation of H2 molecules in the cavities of
Cs3Na9-A zeolite has been proposed. To study the properties of encapsulated H2 molecules, a
Fermi-Dirac like statistics has been introduced. The average binding energy per H2 is obtained as a
function of the number of molecules and temperature. The average activation energy is also calculated
from the minimum energy path for the α- to α-cage transmission and the average binding energy. The
fraction with higher energy than its activation energy has been calculated and revealed that the
activation energy for the en- and decapsulation of H2 molecules depends not only on the temperature
but also on the number of the encapsulated molecules.
Mechanical Strength and Microstructural Characterization of SUS304 Brazed Joints with BNi-2 Filler Metal: Influence of Brazing Temperature and Time
Authors: Lee Yong Won , Kim Jong Hoon , Song Young Sik , Seok Chang Sung
Published: March 2009

The formation of intermetallic compounds in brazed joints between SUS304 and
nickel-based filler metal is a major concern, since they considerably degrade the mechanical
properties of joints. In this study, the SUS304, which is used widespread, as a general material was
vacuum brazed with BNi-2 filler metal, and discussed to determine the influence of different brazing
temperature and time on the strength of brazed joints. The results showed that, the mechanical
properties of brazing layer could be stabilized through increasing the brazing temperature over 100°
C more than melting temperature of filler metal, and increasing the brazing time over 120min. long,
and diffusing enough the intermetallic compounds formed in the brazing layer to the base metal.
Ab Initio Study with Transition State Theory (TST) for the Calculation of the Barrier Height of Migration Energy of Neutral Indium in Silicon
Authors: Yoon Kwan Sun , Won Tae Young
Published: March 2009

In this paper, we present ab-initio study on the energy configurations, minimum energy
path (MEP), and migration energy of neutral indium atom during diffusion in silicon crystal. From the
ab-initio calculation of electronic structure, we could figure out the transient atomistic configurations
during the indium diffusion in silicon. We found that the lowest-energy structure (Ins + Sii
Td) consists
of indium sitting on a substitutional site for stabilizing a silicon self-interstitial in a nearby tetrahedral
position. The second lowest-energy structure was found to be Ini
Td, the interstitial indium at the
tetrahedral position. We employed the climbing image nudged elastic band (CINEB) method for
estimating the MEP between the two local energy minima and the migration energy of the neutral
indium, and obtained the MEP of 0.79 eV.
Role of SrRuO3 Buffer Layers in Enhancing Resistance Changing of Pr0.7Ca0.3MnO3 Films
Authors: Han Seung Woo , Park Kyoung Wan , Sok Jung Hyun
Published: March 2009

Resistance-switching behaviors of the Pr0.7Ca0.3MnO3(PCMO) films based metalinsulator-
metal (MIM) devices has been investigated. In this work, resistance change of PCMO
films deposited with SRO buffer layers by using RF-magnetron sputtering system investigated at
room temperature. The ratio of the resistance change of the PCMO films with SRO buffer layers
in the high-resistance state to that in the low-resistance state turned out to be much lager than that
of the PCMO films without SRO buffer layers. Moreover, The reproducible property of the
fabricated samples were improved. Origin of resistance change is not clear, but PCMO films with
SRO buffer layers have the possibility of application for nonvolatile memory device.
Pore Morphology of Lotus-Type Porous Copper Fabricated by Continuous Casting Technique
Authors: Park J.S. , Hyun Soong Keun , Tane Masakazu , Nakajima Hideo
Published: March 2009

We investigated the pore morphology in lotus-type porous copper fabricated by continuous
casting technique as a function of transference velocity range from 1 to 100 mm･min-1 under
hydrogen gas pressure of 1.0 MPa. Lotus-type porous copper with long cylindrical pores aligned in
one direction parallel to the transference direction was fabricated, which posses a sufficient
uniformity of the porosity and pore size. The pores formed at transference velocity of 1 mm･min-1
were larger than other condition. Necks were observed in these pores, whose formation may be
attributed to bubbling in the melt. The pore size decreased with increasing transference velocity,
while the porosity was not varied much by transference velocity.
Materials Design with Enhanced Temperature Stability of Resonant Frequency for High Frequency Application
Authors: Kim Dong Wan , Hong Kug Sun
Published: March 2009

For low temperature cofired ceramic (LTCC) materials to achieve increase functionality, as
well as low loss and moderate dielectric constant, it is essential to achieve the temperature stability of
the resonant frequency. Facing several empirical approaches toward tuning the temperature
coefficient of the resonant frequency (τf) through the formation of mixtures or a solid-solution
between the two end members with opposite signs of τf, which result in higher dielectric loss, we took
a closer look at the texture engineering that determines the anisotropic dielectric properties in barium
niobate ceramics. We demonstrate the advantage of texture engineering for microwave dielectric
properties including temperature stability by control of crystallographic orientation. Also, the
monoclinic rare earth niobates are investigated as novel microwave dielectric materials. Furthermore,
the stable τf of the rare earth niobates could be efficiently explained through the ferroelastic domain
engineering related to phase transformation.
Effect of Method of Preparation of Cu-Zn-Al Catalysts on DME Synthesis
Authors: Venugopal Akula , Palgunadi Jelliarko , Joo Oh Shim , Jung Kwang Deog
Published: March 2009

A series of Cu-Zn-Al catalysts from the precursors with the hydrotalcite-like structure
were prepared, and these catalysts admixed with γ-Al2O3 were tested for DME synthesis in a
fixed bed flow reactor in a single step. DME synthesis rates were well correlated with the Cu
metal surface of the Cu-Zn-Al catalysts in the admixed catalysts, indicating that DME synthesis
rates would be controlled by methanol synthesis rates.
Performance of Immobilized Quaternary Salt Catalysts in the Synthesis of Dimethyl Carbonate from Propylene Carbonate and Methanol
Authors: Kim Kyung Hoon , Choe Young Son , Ju Hye Young , Park Dae Won , Park Sang Wook
Published: March 2009

The synthesis of dimethyl carbonate(DMC) was investigated using four differently
supported quaternary ammonium salt catalysts to facilitate their separation after the reaction. The
different catalysts are (1) C1 on poly(ST-co-VBC), (2) C2 on poly(ST-DVB-VBC), (3) C3 on
macroporous poly(ST-DVB-VBC), (4) C4 on modified MCM-41. The synthesis of DMC was
performed in an autoclave under carbon dioxide pressure. The main byproduct was propylene glycol.
The immobilized quaternary ammonium salt catalysts showed good catalytic activity for the synthesis
of DMC. The order of the reactivity for the catalysts of different support was C1>C3>C2>C4. The
catalysts can be reused for four successive runs without considerable loss of their initial reactivity.
Preparation of Silica-Supported Nickel Molybdenum Phosphides by Temperature-Programmed Reduction Technique
Authors: Lee So Yeon , Lee Yong Kul , Oyama S.Ted , Lee Seok Hee , Woo Hee Chul
Published: March 2009

Silica supported nickel molybdenum phosphides (NiMoP/SiO2) were successfully
prepared by temperature-programmed reduction (TPR) reaction of phosphorous-impregnated nickel
molybdenum oxides (NiMoO4) precursors with hydrogen at relatively low temperatures (530 – 590
oC) and characterized by Fourier transform-Infrared spectrometry (FT-IR), X-ray diffraction (XRD),
Electron probe microanalysis (EPMA) and Temperature-programmed reduction reaction (TPR). The
process of solid transformation and properties of materials prepared from ammonium hydrogen
phosphate (AMP)-impregnated samples were compared with those of phosphide made from
phosphoric acid (PAC)-impregnated samples. Results show that the formation of a single NiMoP
phase on silica significantly depends on reduction rates, phosphorous sources and phosphorous
loadings. A single phase of NiMoP on SiO2 was particularly promoted at a below 5 oC/min of
reduction rate and the starting molar ratio of Ni/Mo/P=1/1/1. A single phase of crystalline NiMoP
on silica was produced from AMP-impregnated samples, while other phases of MoP, Ni2P, or
NiMoP2 were appeared from PAC-impregnated samples with loading. The new phase of NiMoP2
was occurred with increasing phosphorous loading (above Ni/Mo/P=1/1/2.5) as a result of
facilitated contact on the surface between the Ni-Mo bimetallic component and the phosphorous
reagent
Synthesis of Dense Mesoporous Silica with High Surface Area by Hydrothermal Hot-Pressing (HHP) Method
Authors: Takimura Mari , Nagata Hidezumi , Yamasaki Yuki , Nakahira Atsushi
Published: March 2009

In this study, the synthesis of the bulky and dense mesoporous silica such as FSM was attempted
by a hydrothermal hot-pressing (HHP) with a surfactant as a template and a subsequent calcination.
According to TEM observation, the dense bulks obtained by HHP had a hexagonal mesopore
structure. Also, these dense FSM bulks possessed high specific surface areas. Furthermore,
Ag-supported dense FSM bulks were successfully synthesized by HHP with Ag salt and a
subsequent calcination in H2. Thus, this HHP method is useful for synthesizing dense bulks and
simultaneous supporting novel metals such as Ag on bulky FSM.
Adsorption Properties of Activated Carbon Fibers Characterized by Electric Decomposition
Authors: Hong Ik Pyo , Lee Seong Young , Park Sei Min , Jin Hang Kyo
Published: March 2009

Pitch based activated carbon fibers(ACFs) were characterized by electric decomposition
method in the various kinds of acid electrolyte. The felt-type commercialized ACFs were used as raw
material and the acids such as HCl, H2SO4, HNO3 and HF were used as electrolytes for electric
decomposition. ACFs were treated with 0.7 ~ 2.0A/g-ACF of DC as an anode material for few hours
in the acid electrolyte bath and voltage was varied 10~50V according to the condition of current and
electrolyte. The pore properties of surface characterized ACFs were measured by adsorption analyzer
and changes of surface morphology were also observed by scanning electron microscope and
transmitting electron microscope. In order to estimate possibility of use as hydrogen storage material,
hydrogen adsorption amount was measured with high pressure thermogravimetric analyzer. In the
result the pore size distribution of surface characterized ACFs were changed with respect to electric
decomposition condition, especially species and concentration of electrolytes and hydrogen
adsorption amount also changed according to pore properties of ACFs.
Dome-Shaped High Power Transformer for Driving A 55 W PL Lamp
Authors: Yoon Man Soon , Kim H.K. , Ur Soon Chul
Published: March 2009

Processing and properties of a dome-shaped piezoelectric transformer with a
composition of 0.03Pb(Sb0.5Nb0.5)O3-0.03Pb(Mn1/3Nb2/3)O3-0.465PbTiO3-0.475PbZrO3
have been investigated. A dome-shaped sample was fabricated by powder injection
molding. The dimension of the dome-shaped sample was a 28 mm in diameter and
2.1mm in thickness with a curvature radius of 18 mm. Finite element modeling for the
complicated piezoelectric transformer was applied to simulate vibration mode in the
sample. The high power characteristics of a dome-shaped piezoelectric transformer
were examined by the lighting test for a 55W PL lamp. The 55W PL lamp was
successfully driven by the dome-shaped piezoelectric transformer with sustaining
efficiency higher than 98%. The transformer with ring/dot area ratio of 2.1 exhibited the
maximum properties in terms of output power, efficiency and temperature stability.
Preparation and Characterization of SnO2 Thin Film Gas Sensor for NOx Gas for Environmental Monitoring
Authors: Bhuiyan Md. Mosharaf Hossain , Ueda Tsuyoshi , Ikegami Tomoaki
Published: March 2009

SnO2 thin films have been grown on Si3N4 substrates and also on Al2O3 sensor substrates
with Pt interdigitated electrodes by the pulsed excimer laser deposition (PLD). Palladium doped
SnO2 thin film was also prepared by the PLD method combined with the DC sputtering process.
The substrate temperature and the oxygen gas pressure were changed from 300 to 500°C and from
100 to 300 mTorr, respectively during deposition. The morphology and structural properties of the
prepared thin films have been studied by AFM and XRD. The gas sensing properties of the SnO2
sensor to NO gas was evaluated by measuring electrical resistance between interdigitated electrodes.
The highest sensitivity of the undoped SnO2 and Pd doped sensor was found to be around 9.5 and
42, respectively.
Electrical and Thermal Properties of Platinum Thin Films Prepared by DC Magnetron Sputtering for Micro-Heater of Microsensor Applications after CMP Process
Authors: Kim Nam Hoon , Na Dong Myong , Ko Pil Ju , Park Jin Seong , Lee Woo Sun
Published: March 2009

Chemical mechanical polishing (CMP) of platinum thin films was performed for the
improvement of surface morphology. Platinum thin films after CMP process with alumina slurry
showed the increase of surface morphology without a remarkable difference of the thermal
characteristics of as-annealed platinum thin films. The power consumption of platinum thin films
micro-heater also became very low by improvement of surface morphology after CMP process. The
similar or improved electrical and thermal characteristics of platinum thin films for micro-heater of
sensor applications as well as evaluation possibility of sensing property by the improved surface
morphology were obtained after CMP process.
Nickel-Based Germanosilicide of Heavily-Doped SiGe Films for Low Resistance and High-Temperature Stability
Authors: Choi A Ram , Choi Sang Sik , Kim Jung Hyun , Kim Sang Hoon , Shim Kyu Hwan
Published: March 2009

We have studied thermo-electrical properties for Ni-based germanosilicide to understand
the influence of temperature on the evolution of sheet resistance and micro-structures of contacts on
heavily-doped SiGe grown by reduced pressure chemical vapor deposition. After the deposition of Ni,
Ni/Ti, Ni/Pt films on Si0.83Ge0.17 epi layer and subsequently annealing for silicide reaction, we
analyzed sheet resistance, surface roughness and reaction interfaces using four point probe method,
scanning probe micrograph and transmission electron microscope. Bi-layer metal structures of Ni/Ti
and Ni/Pt were investigated to study feasible use for suppressing inappropriate reaction at interface. It
is found that bi-layer structure with thin Pt interlayer presented promising properties for
germanosilicide of n+-Si0.83Ge0.17 with low sheet resistance, smooth surface morphology and high
temperature stability up to 800 oC.
Study on the Synthesis and Characterization of PANi/Nano-CeO2 Composites
Authors: Liu Fei , He Yong Jun , Huh Jeung Soo
Published: March 2009

The nano-CeO2 was synthesized by two-step solid-phase reaction. The image of TEM
showed that nano-CeO2 with an average size of about 70 nm. The series of polyaniline/nano-CeO2
composites with different PANi: CeO2 ratios were prepared by in-situ polymerization in the presence
of hydrochloric acid (HCl) as dopant by adding nano-CeO2 into the polymerization reaction mixture
of aniline. The composites obtained were characterized by FT-IR and UV-vis spectroscopy analysis.
The FT-IR spectra of nanocomposites indicate different blue-shifts, attributed to C–N stretching
mode for benzenoid unit. The UV-vis spectra of nanocomposites display einstein-shifts compared
with PANi at 620nm. The conductivity properties of the composites are also changed compare to the
pure PANi. These results suggest that the interactions between the polymer matrix and nanoparticles
take place in polyaniline/nano- CeO2 composites.
Luminescence of MWO4 (M =Ca, Sr, Ba and Pb) Prepared by Solvothermal Reaction
Authors: Thongtem Titipun , Kaowphong Sulawan , Thongtem Somchai
Published: March 2009

MWO4 (M = Ca, Sr, Ba and Pb) was solvothermally prepared using metallic nitrates and
sodium tungstate in 25/5 volume ratios of glycerol/water (SGL) and propylene glycol/water (SPG)
at 160 oC for 6 h. XRD revealed the presence of MWO4 single phase with tetragonal scheelite
structure. The strong W-O stretching band of WO4 tetrahedrons was detected at 705-875 cm-1. The
product images show nano-sized particles in basic SGL and SPG solvents and flower-like particles
in SPG solvent with pH of 6.7. Central peaks of the luminescent spectra are 445, 446, 443 and 440
nm, respectively.
Dependency of Electrical Characteristics on Au Nano-Crystal Size for Non-Volatile Memory Fabricated with Au Nano-Crystal Embedded in PVK(Poly(N-Vinylcarbazole)) Layer
Authors: Lee Chang Kyu , Kwon Jong Sung , Na In Chul , Han Byung Il , Kim Young Min , Park Jea Gun
Published: March 2009

We demonstrated a nonvolatile memory fabricated with the sandwich device structure of
Al/Au nano-crystals embedded in the PVK/Al. The bi-stable conduction switching characteristic
(Ion/Ioff ratio) was >1x102, depending on Au nano-crystal size. The size and distribution of Au
nano-crystals were determined by the inserted Au-layer thickness between PVK layers. The size of
Au nano-crystals increased with the inserted Au-layer thickness. The uniform distribution of isolated
Au nano-crystals was obtained with 5 nm of the inserted Au-layer thickness.
Hydrogen Plasma Process to Reduce the Eu-Doped Sr2SiO4 Thin Films
Authors: Kim Sung Hoon , Yun Hong Seop , Yang Hyun Kyung , Kim Kwang Duk , Yi Soung Soo , Jeong Jung Hyun , Kim Dong Uk
Published: March 2009

As-grown Sr2SiO4:Eu thin films on Si (100) substrates have been reduced by hydrogen
plasma reaction which was carried out by using radio frequency plasma enhanced chemical vapor
deposition system. The photoluminescence spectra, the crystal structure and the surface morphologies
of the plasma-reduced films were measured and compared with those of the as-grown films. At
as-grown state, Eu3+ and Eu2+ ions co-exist so that the photoluminescence spectra of the films reveal
several emission bands between 350 and 650 nm. They were due to f-f and f-d transitions within Eu3+
and Eu2+ ions. After the plasma-reduced process, the photoluminescence spectra of the films show a
remarkable increase of blue-green emission from the transitions of Eu2+ ions and decrease of red
emission from the transitions of Eu2+ ions.
Improvement of Luminescent Properties of Phosphor Powders Coated with Nanoscaled SiO2 by Atomic Layer Deposition
Authors: Kim Hyu Suk , Kim Hyug Jong , Kim Hyung Su , Jeong Young Kyu , Kim Suk Hwan , Lee Sang Woo , Jeong Bong Kyo , Lee Hyuoung Ho , Choi Byung Ho
Published: March 2009

An investigation is reported by coating BaMgAl10O17:Eu2+ phosphor by silicon oxide using
catalyzed atomic layer deposition. Nanoscaled SiO2 films were prepared at room temperature using
tetraethoxysilane (TEOS), H2O and NH3 as precursors, reactant gas and catalyst, respectively. AES
analysis showed the surface composition of coated phosphor was silicon oxide. In TEM and FE-SEM
analysis, the growth rate was about 0.7 Å/cycle and the surface morphology became smoother and
clearer than that of uncoated phosphor. The photoluminescence intensity (PL) increased up to 11.04%
as ALD cycle increased up to 200 ALD cycle. This means that the reactive surface of uncoated
phosphors is uniformly grown with stable silicon oxide to reduce the dead surface layer without
change of bulk properties. Moreover, it is found that nanoscaled SiO2 films are quite effective for the
improvement of the aging characteristics of photoluminescence.
Prevention of Thin Film Failures for PECVD Amorphous-Si on Plastic Substrate
Authors: Seo Jong Hyun , Jeon Jae Hong , Choe Hee Hwan
Published: March 2009

Amorphous silicon thin films were deposited below 160oC on PES plastic films using
PECVD. After thin film deposition using PECVD, thin film failures such as film delamination and
cracking often occurred. For successful growth of thin films (about 2000 Å) without their failures, it is
necessary to solve the critical problem related to the internal compressive stress (some GPa) leading
to delamination at a threshold thickness value of the films. The Griffith’s theory explains the failure
process by looking at the excess of elastic energy inside the film, which overcomes the cohesive
energy between film and substrate. In this work, reducing a-Si layer film thickness and optimizing a
barrier SiNx layer have produced stable a-Si films at 150oC, over PES substrates.
Low Temperature O2 Plasma-Assisted Wafer Bonding of InP and a Garnet Crystal for an Optical Waveguide Isolator
Authors: Roh J.W. , Yang J.S. , Ok S.H. , Woo Deok Ha , Byun Young Tae , Jhon Young Min , Mizumoto Tetsuya , Lee Woo Young , Lee Seok
Published: March 2009

A novel process of wafer bonding between InP and a garnet crystal (Gd3Ga5O12,
CeY2Fe5O12) based on O2 plasma surface-activation and low temperature heat treatment is presented.
The O2 plasma assisted wafer bonding process was found to be very effective in bonding of InP and
Gd3Ga5O12, providing good bonding strength and hydrophilicity as well as no voids in the interface,
which is crucial for fabrication of an integrated optical waveguide isolator. The isolation ratio of an
integrated optical waveguide isolator fabricated by the O2 plasma assisted wafer bonding process was
obtained to be 2.9 dB.
Preparation and Property of Nonlinear Optical Materials Based on K2O-BaO-TiO2-SiO2 Glasses
Authors: Lee Hoi Kwan , Chae Su Jin , Kang Won Ho
Published: March 2009

Transparent fresnoite(Ba2TiSi2O8) glass-ceramics considered as a new type of non-linear
optical materials have been prepared by controlled heat treatment in the system
xK2O-(33.3-x)BaO-16.7TiO2-50SiO2(0≤x≤20 mol%), and optical properties were investigated. The
glassy nature was analyzed by differential thermal analyses. The transparency of glass-ceramics was
variable and controllable by the processing parameters like time and temperature. The transparent
glass-ceramics showed second harmonic generation (SHG) when irradiated by a 1064nm laser beam
(Nd:YAG). The SHG intensity was compared with a Y-cut α-quartz plate.
Detection of Toxic Organophosphate Nerve Agents Using DBR Porous Silicon Chip
Authors: Lee Bong Ju , Jang Seung Hyun , Sohn Hong Lae
Published: March 2009

The efficient detection method based on nanostructured photonic DBR PSi has been
developed for DMMP, which is a simulant for G-type nerve agents. The manufactured DBR PSi
chip exhibits a sharp photonic band gap at 520 nm. The detection method involves the shift of DBR
peak in reflectivity spectra under the exposure of vapors of analyte. Rapid detection has been
achieved in few seconds, in situ, and observed by the red-shift of DBR peak resulted from the
increase of refractive indices in DBR PSi. When DBR PSi chip is exposed to DMMP, TEP, and
DEEP-saturated air, DBR peak in reflectivity is red shifted by 10 nm, 25 nm, and 10 nm,
respectively. Real-time detection for the nerve gases indicates that the measurement is reversible.
Detection limit of DMMP (1.5 ppm) using DBR PSi is 8.8 mg/m3 for 1 min.
Formation of Nanocrystallites in the nc-Si Films by Co-Sputtering Aluminium and Silicon
Authors: Shim Jae Hyun , Cho Nam Hee
Published: March 2009

The nanostructural and optical features of Al-doped Si thin films, which were prepared by
co-sputtering Al-chips and a Si main target, were investigated in terms of Al-doping and
post-deposition heat-treatment conditions; the heat treatment was carried out at temperatures of 400 ~
1100 °C. The structural and chemical features are related with the photoluminescence (PL)
phenomena of the films. The PL intensity as well as the concentration of Si nanocrystallites were
increased by doping particular amount of Al in the films.
Inductively Coupled Plasma Reactive Ion Etching of Ge-SiO2 and SiON Using C2F6 and NF3-Based Gas Mixtures
Authors: Kim N.J. , Lee S.Y. , Lee G.K. , Moon J.H. , Lee Byung Teak
Published: March 2009

Inductively coupled plasma reactive ion etching of Ge doped silica glasses and SiON was
investigated, using C2F6- and NF3-based gas mixtures. Mesas with smooth surfaces and vertical
sidewalls were obtained, with a maximum etch rate of about 310nm/min in the case of C2F6 RIE of
Ge-SiO2 and 280 nm/min in the case of SiON. The NF3 plasma yielded slightly higher etch rate,
although sloped sidewalls were obtained. Results of the X-ray photoelectron spectroscopy showed
little contamination on the etched surfaces.
The Calculation of Adatom Diffusion Process on Si and Ge Surfaces from First-Principles
Authors: Chang Ki Seok , Yoon Young Gui
Published: March 2009

We study Si adatom diffusion process near Si/Ge stepped surfaces from first-principles.
Dependence of surface growth morphology on growing conditions such as temperature is not clearly
understood. We calculate Ehrlich-Schwoebel(ES) barrier of stepped surfaces from first-principles and
analyze adatom diffusion process to understand growth mechanism of the surfaces. The configuration
of the surfaces with ES barrier would play a key role in the diffusion process because it controls
hopping rates in the presence of step edges. Our results are likely to help correctly access the adatom
diffusion process on the surfaces.
Formation and Optical Properties of ZnSe Self-Assembled Quantum Dots in Cl-Doped ZnSe Thin Films Grown on GaAs (100) Substrates
Authors: Panin G.N. , Kim H.J. , Kim S.Y. , Jung J.H. , Kim Tae Whan , Jeon H.C. , Kang T.W. , Kim M.D.
Published: March 2009

The high-resolution scanning electron microscopy (HRSEM) image showed that selfassembled
ZnSe small quantum dots (QDs) and large nanodots with a pyramid shape were formed
in the Cl-doped ZnSe epilayers grown on GaAs (100) substrates. The formation of the ZnSe QDs
was attributed to three-dimensional growth controlled by distribution of the impurities in the Cldoped
ZnSe epilayrs. Cathodoluminescence (CL) measurements at room temperature revealed the
emission peak at 3.1 eV corresponding to the blue shift approximately 400 meV from the near band
edge emission of 2.7 eV in the bulk ZnSe. The blue shifted CL peak indicates the quantum
confinement effect resulting from the formation of the ZnSe QDs in the Cl-doped ZnSe thin film.
While the peak position of the donor-acceptor pair emission shifted to higher energies with
decreasing temperature, the band-edge emission peak for the QDs did not significantly change.
Phase Field Study for Self-Assemble of the Second Phase Particles in Coherent Phase Transition
Authors: Kim Jin You , Yoon Jong Kyu , Kim Yoo Chan , Suck Hyunn Kwang , Kim Ki Bae , Cha Pil Ryung
Published: March 2009

We present a phase field model for coherent phase transition and its application to the
self-assembled arrangement of second phase particles in coherent phase transition. The model
developed here is free from the interface instability due to the contribution of chemical free energy
and correctly describes elastically inhomogeneous system. It is observed that coherent misfit strain
and anisotropy of elastic constants induce the interface instability that brings about the particle
splitting and the self-assembled alignment of second phase particles. Their arrangement to the
elastically soft direction occurs only in the system where the elastic contant of the precipitates is larger
than that of the matrix phase.
Local Work Function Measurements on Various Inorganic Materials Using Kelvin Probe Force Spectroscopy
Authors: Kim Chan Hyung , Bae Chang Deuck , Ryu Kyung Hee , Lee Bong Ki , Shin Hyun Jung
Published: March 2009

In this study, we measured work functions on various materials (i.e., metals and
semiconductors) using Kelvin probe force spectroscopic method. Since the Kelvin probe force
microscopic (KPFM) method allow to determine the work function difference between the metallic
tip and unknown work function samples, it is very important that work function of the tip is accurately
defined. Therefore, all the conductive tips were calibrated with a freshly cleavaged highly oriented
pyrolytic graphite (HOPG). Work function measurements on various materials are conducted by
using these calibrated tips. The values of work functions of metal films (i.e., Au and Pt) obtained in
this method were found to correspond to the values reported in the literature, but those for
semiconductor materials (i.e., n-, p-type Si and ITO films) show some deviations from their work
functions which would be found in the literature. Surface electronic band bending and geometry of the
tip could affect the differences in work functions measured by KPFM technique.
Interface Influence on the Proton-Conductivity of Ordered Mesoporous Silica Membranes
Authors: Xiong Liang Ming , Nogami Masayuki
Published: March 2009

As an alternative to a solid-state electrolyte for proton exchange membrane fuel cells
(PEMFCs), ordered mesoporous membranes (OMMs) were prepared using a sol-gel technique,
followed by a deep-UV irradiation. Structure and impedance spectroscopy analyses revealed that the
porous architecture and proton conductivity of OMMs were influenced by the nature of the substrates.
Compared with hydrophilic substrate, hydrophobic substrate was beneficial to an accessible porous
architecture in the interface layer and an increase of proton conductivity of the whole membrane. The
proton conductivity of the OMMs was up to 10-3 S cm-1.
Electrical Properties BaTiO3 Thick Films with an Interlayer SrTiO3 Thin Films
Authors: Nam Sung Pill , Lee Sung Gap , Bae Seong Gi , Lee Young Hie
Published: March 2009

The BaTiO3/SrTiO3 heterolayered thick films were fabricated by two different methods –
thick films of BaTiO3 by screen printing method on alumina substrates electrodes with Pt, thin films
of SrTiO3 by the spin-coating method on BaTiO3 thick films and once more thick films of BaTiO3 by
the screen printing method on SrTiO3 layer. The leakage current and the dielectric properties were
investigated for effect of various stacking sequence of sol-gel-prepared SrTiO3 layer at interface of
BaTiO3 thick films. The insertion of SrTiO3 interlayer yielded BaTiO3 thick films with homogeneous
and dense grain structure with the number of SrTiO3 layers. The leakage current density of the
BaTiO3/SrTiO3-7 film is less that 1.5 10-9 A/cm2 at 5 V.
Surface Strengthening of Zirconia Toughened Alumina (ZTA) Using Glass Infiltration Technique
Authors: Balakrishnan A. , Chu Min Cheol , Panigrahi B.B. , Yoon K.J. , Kim J.C. , Lee Byoung Cheon , Kim Taik Nam , Cho Seong Jai
Published: March 2009

Molten Soda lime glass (SLG) was penetrated into the surface of ZTA at 1500°C for the
holding time of 1 to 10 h. The depth of the glass penetration increased with increasing holding time.
The thermal expansion mismatch and elastic property mismatch between the penetrated glass and
ZTA produced residual compression in the surface region during cooling. This residual compression
enhanced the flexural strength and fracture toughness remarkably.
Preparation and Characterization of Cordierite-Bonded Silicon Carbide Porous Ceramics
Authors: Lee Jin Seok , Choi Do Mun , Choi Sung Churl
Published: March 2009

Cordierite-bonded silicon carbide porous ceramics were prepared by a reactive process, in
which kaolin, talc, and alumina powders were mixed with silicon carbide powders and graphite
powder was used as a pore former. The mixture was heated in air so that graphite was burned out and
silicon carbide particles were bonded by reaction-derived cordierite. Open porosity and strength of
porous ceramics were strongly dependent on the volume fraction of graphite and cordierite. A
three-point bending strength of 13.9 MPa was achieved at a open porosity of 38.5 %, exhibiting
coefficient of thermal expansion of 7.28 × 10-6/oC at the range of 25 – 800oC. Increase of cordierite
volume in SiC matrix indicated mechanical improvement of the porous ceramics due to the increase
of neck area among the SiC particles. Porous ceramics sintered at 1450oC possessed higher open
porosity and median pore diameter than those of samples sintered at 1250 and 1350oC, since pore
generated by the transport of dissolved talc materials as increasing temperature.
Photocatalytic Properties of Anodic TiO2 Nanotubes
Authors: Lee Jong Ho , Choi Hyung Seon , Jeong Yong Soo , Chi Choong Soo , Oh Han Jun
Published: March 2009

The anodic titania nanotubular films for photocatalyst were synthesized by anodic
oxidation in HF electrolyte, and the photocatalytic properties of anodic TiO2 layer were investigated.
The self organized anodic TiO2 film consisting of nanotubes with diameter of 100-150 nm as
photocatalyst can be obtained by electrochemical method at a constant potential of 20 V for 40 min in
HF solution. In order to improve the photocatalytic efficiency the anodic titania nanotube was heat
treated at 550oC for 1h. In the evaluation of dye degradation, heat treated catalyst shows much higher
efficiency than non-heat treated one.
Study on the Durability of E-Glass Fiber/Vinylester Resin Composites in Various Environment
Authors: Lee Seung Yul , Ahn Byung Hyun , Moon Chang Kwon
Published: March 2009

The effect of various environmental conditions on durability of E-glass fiber/vinylester resin
composites has been investigated with tensile test specimen of strand type. The durability test method
performed by strand type specimen was more convenient and reliable than other conventional test method. The
weight gain of E-glass fiber reinforced composites increased with the immersion time in both water and alkali
solutions, and the weight gains at 80°C were a little greater than ones at 20°C. The tensile strength decreased
with the immersion time in all aqueous solution, and the tensile strength in 80°C of alkaline solution decreased
most rapidly. The decrement of tensile strength in various environmental conditions was mainly caused by the
degradation of interface and damage of glass fiber surface.
The Effect of the Geometrical Shape and Size of the Cross Section on the Spin-Polarized Transport and the Giant Magnetoresistance : Finite Element Method Analysis
Authors: Noh Eun Sun , Ulloa Sergio E. , Lee Hyuck Mo
Published: March 2009

We analyze the effect of the geometrical shape and size of the cross section on the
spin-polarized transport and the giant magnetoresistance (GMR) by a finite element method, and
evaluate the stability and the physical properties of nano-scale spin valves. We calculate the
transmission coefficients in the ballistic regime by using a transfer-matrix method, and evaluate the
GMR of the current perpendicular to the plane (CPP) by using a circuit theory. The conduction-band
structure is simplified to the potential step, which is determined by combining the interfacial
parameters calculated by first-principles with the free electron model. The geometrical shapes of the
cross section are line and square. As a result, the cross sectional shape has a significant effect on the
spin-polarized transport and the GMR. The square-shaped cross section has an advantage of the large
GMR, which is contrary to the line-shaped cross section. These phenomena result from the difference
of the cut-off energies with the transverse modes and, consequently, the different spin-down
transmission coefficients.
Magnetic Properties of Various Thick Co-Fe Circular Dot Arrays
Authors: Endo Yasushi , Niimi Yusuke , Nakatani Ryoichi , Kawamura Yoshio , Yamamoto Masahiko
Published: March 2009

We have studied the magnetic properties of Co-Fe circular dot arrays with various
thicknesses and diameters in order to determine the optimum thickness and diameter of these dot
arrays with a single-domain state for the transmission of spin information. For the thickness of 10 nm,
the magnetic state changes from a multi-domain state to a closure-domain state and further to a
single-domain state with decreasing diameter. On the other hand, for the thickness of 30 nm and 50
nm, all magnetic states are in a vortex state, regardless of the diameter. From these results, it is found
that the optimum thickness and diameter of Co-Fe circular dots with a single-domain state are,
respectively, 10 nm and less than 100 nm.
Magnetic Properties of Mn-Zn Ferrite Nanoparticles Fabricated by Conventional Ball-Milling
Authors: Je Hae June , Kim Byung Kook
Published: March 2009

Mn-Zn ferrite nanoparticles were fabricated via conventional ball-milling and their
magnetic properties were investigated. By ball-milling of Mn0.53Zn0.42Fe2.05O4 agglomerates for 48h
with and without a dispersant (Darvan-C (ammonium polymethacrylate)), nanoparticles having
average particle size of 60 nm were obtained. The saturation magnetizations (Ms) of thus obtained
Mn-Zn ferrite nanoparticles were 49 and 62 emu/g for dispersant-added and dispersant-non-added
one, respectively. When the nanoparticles were heat-treated at 400, however, the Ms became
comparable: 63 and 65 emu/g. When the nanoparticles were heat-treated at 600, moreover, the Ms
became comparable with that of bulk ferrites: 75~78 emu/g. These magnetic properties were
attributed to the surface spin disorder effects resulting from the coating of organic dispersant
molecules on the surfaces of the nanoparticles as well the structural disorder on the surfaces the
nanoparticles.
The Selective Protein Separations with Polyaminofunctionality on Controlled Silica Coating-Layers of Magnetic Nanoparticles
Authors: Park Moo Eon , Kang Ki Ho , Kim Kyung Ja , Chang Jeong Ho
Published: March 2009

This work reported the development of the high throughput protein separation process with
molecularly assembled silica-coated magnetic nanoparticles as a function of amino group numbers
such as mono-, di-, and tri-aminofunctionality, in which the range of silica coating thicknesses were
optimized to be interacted with protein. The protein separation efficiency was demonstrated as a
function of each aminofunctional group and the particle sizes of the silica coated magnetic
nanoparticles. The particles were prepared by the chemical precipitation of Fe2+ and Fe3+ salts with a
molar ratio of 1:2 under basic solution. The silica coated magnetic nanoparticles were directly
produced by the sol-gel reaction of a tetraethyl orthosilicate (TEOS) precursor, in which the coating
layer serves as a biocompatible and versatile group for further biomolecular functionalization. To
effectively capture the proteins, silica coated magnetic nanoparticles need to be functionalized
reproducibly on the silica surface, and three kinds of amino functional groups were adapted as a
function of number of amine using the mono-, di-, and tri-aminopropylalkoxysilanes.
DLC Film Coating on a Lithium Metal as an Anode of Lithium Secondary Batteries
Authors: Shim Heung Taek , Lee Joong Kee , Cho Byoung Won
Published: March 2009

In order to enhance the electrochemical performance of lithium metal as an anode of
lithium secondary battery, we prepared DLC film coating with various morphologies using a
radio-frequency chemical vapor deposition method. Raman spectroscopy and FT-IR analyses
revealed that the DLC film consists of mixture of graphitic sp2 and aliphatic sp3 hybridized bonds.
DLC coating on lithium metal electrode play an important role as a passive layer during
electrochemical reaction. Based on experimental results, we expected that the well dispersed DLC
film coating sector as small as possible on the lithium metal electrode exhibits excellent
electrochemical performance such as irreversible capacity and cycling performance.
Effect of Various Lithium Salts in TEGDME Based Electrolyte for Li/Pyrite Battery
Authors: Choi Jae Won , Cheruvally Gouri , Shin Yong Jo , Ahn Hyo Jun , Kim Ki Won , Ahn Jou Hyeon
Published: March 2009

The effect of lithium salts such as LiPF6, LiBF4, LiCF3SO3 and LiN(CF3SO2)2 (LiTFSI) in
tetra(ethylene glycol) dimethyl ether (TEGDME) electrolyte on the ionic conductivity, interfacial
resistance and discharge properties of Li/pyrite cell at room temperature was studied. The electrolytes
had good ionic conductivity at room temperature in the range 0.61 to 1.86 × 10-3 S/. The discharge
capacities of Li/pyrite cells with 1M LiPF6 and LiBF4 in TEGDME were lower compared to those of
the other two non-HF containing salts. The best cycle performance was exhibited by LiTFSI in
TEGDME electrolyte, with a discharge capacity of 438 mAhg-1 after 20 cycles, which is ~49% of
FeS2 theoretical capacity (894 mAhg-1). The good performance of LiTFSI-TEGDME electrolyte
resulted mainly from its low interfacial resistance in Li/FeS2 cells, which showed a decreasing trend
with cycling.
Effects of Se Atmosphere on the Densification of Absorber Layer Using Cu(In,Ga)Se2 Nanoparticles for Solar Cells
Authors: Kim Ki Hyun , Ahn Se Jin , Ahn Byung Tae , Yoon Kyung Hoon
Published: March 2009

To make a dense CIGS absorber layer, spray deposited CIGS films were annealed in the
two-zone RTP furnace in Se atmosphere. More Se supply by increasing Se evaporation temperature
or by increasing the flow rate of carrier gas resulted in the larger CIGS grains. However, a thick
MoSe2 layer was formed between CIGS and Mo, as the Se supply increased, results in partial
detachment of CIGS/MoSe2/Mo layers from the glass substrate. From the result, it was found that
the short heat- treatment with high Se vapor pressure is better than the long heat-treatment with low
Se vapor pressure. The large CIGS grains without peeling off, can be obtained from the following
conditions; Se evaporation temperature of 450oC, substrate temperature of 550oC, annealing time of
5 min, and flow rate of carrier gas of 30 sccm.