• 한국재료학회지
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• 제15권5호
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• pp.301-305
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• 2005

We fabricated nickel silicide layers on whole non-patterned wafers from $p-Si(100)SiO_2(200nm)$/poly-Si(70 nm)mn(40 nm) structure by 40 sec rapid thermal annealing of $500\~900^{\circ}C$. The sheet resistance, cross-sectional microstructure, surface roughness, and phase analysis were investigated by a four point probe, a field emission scanning electron microscope, a scanning probe microscope, and an X-ray diffractometer, respectively. Sheet resistance was as small as $7\Omega/sq$. even at the elevated temperature of $900^{\circ}C$. The silicide thickness and surface roughness increased as silicidation temperature increased. We confirmed the nickel silicides iron thin nickel/poly-silicon structures would be a mixture of NiSi and $NiSi_2$ even at the $NiSi_2$ stable temperature region.

• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.165-171
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• 2013

Nanostructured pure a-C and nitrogen doped a-C: N thin films with small particle size of, ~50 nm were obtained by Aerosol-assisted CVD method from the natural precursor camphor oil. Five samples were prepared for the a-C and a-C: N respectively, with the deposition temperatures ranging from $400^{\circ}C$ to $600^{\circ}C$. At high temperature, the AFM clarifies an even smoother image, due to the increase of the energetic carbon ion bombardment at the surface of the thin film. An ohmic contact was acquired from the current-voltage solar simulator characterization. The higher conductivity of a-C: N, of ${\sim}{\times}10^{-2}Scm^{-1}$ is due to the decrease in defects since the spin density gap decrease with the nitrogen addition. Pure a-C exhibit absorption coefficient, ${\alpha}$ of $10^4cm^{-1}$, whereas for a-C:N, ${\alpha}$ is of $10^5cm^{-1}$. The high ${\sigma}$ value of a-C:N is due to the presence of more graphitic component ($sp^2$ carbon bonding) in the carbon films.

• 한국전기전자재료학회논문지
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• 제25권5호
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• pp.349-352
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• 2012

ZnO thin films were deposited on a-, c- and m- plane oriented 4H-SiC substrates by pulsed laser deposition. ZnO nanowires were formed on substrates by tube furnace. Shape and density of the ZnO nanowires were investigated by field emission scanning electron microscope. Average surface roughness and root mean square surface roughness were measure by atomic force microscope. Optical properties were investigated by Photoluminescence measurement. Density of ZnO nanowires grown on a-, c- and m-plane oriented 4H-SiC substrates were 17.89 ${\mu}m^{-2}$, 9.98 ${\mu}m^{-2}$ and 2.61 ${\mu}m^{-2}$, respectively.

• 한국분말재료학회지
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• 제16권3호
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• pp.217-222
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• 2009

This paper presents a novel single-step method to prepare the Ag nanometallic particle dispersed fluid (nanofluid) by electrical explosion of wire in liquid, deionized water (DI water). X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to investigate the characteristics of the Ag nanofluids. Zeta potential was also used to measure the dispersion properties of the as-prepared Ag nanofluid. Pure Ag phase was detected in the nanofluids using water. FE-SEM analysis shows that the size of the particles formed in DI water was about 88 nm and Zeta potential value was about -43.68 without any physical and chemical treatments. Thermal conductivity of the as-prepared Ag particle dispersed nanofluid shows much higher value than that of pure DI water.

• 한국군사과학기술학회지
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• 제14권1호
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• pp.15-21
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• 2011

In this paper, the results of experimental analysis for the chemical composition and strengh verification of Bailey Panel Bridge have been presented. Some of main sections of bailey bridge colllected from military engineer troops were prepared for the chemical composition and strengh verification. The composition test and strength verification were conducted by using the optical microscope and Scanning Electron Microscope(SEM), Automatic Control Spark Emission Spectrometer(OBLF), X-ray Fluorescence Spectroscopy(XRF) and Instron measurement. The results showed that currently used sections of bailey bridge passed the strength verification and could be operated in drill of troops and battle fields.

• 한국재료학회지
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• 제16권9호
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• pp.564-570
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• 2006

Silicides have been required to be below 40 nm-thick and to have low contact resistance without agglomeration at high silicidation temperature. We fabricated composite silicide layers on the wafers from Ni(20 nm)/Co(20 nm)/poly-Si(70 nm) structure by rapid thermal annealing of $700{\sim}1100^{\circ}C$ for 40 seconds. The sheet resistance, surface composition, cross-sectional microstructure, and surface roughness were investigated by a four point probe, a X-ray diffractometer, an Auger electron spectroscopy, a field emission scanning electron microscope, and a scanning probe microscope, respectively. The sheet resistance increased abruptly while thickness decreased as silicidation temperature increased. We propose that the fast metal diffusion along the silicon grain boundary lead to the poly silicon mixing and inversion. Our results imply that we may consider the serious thermal instability in designing and process for the sub-0.1 um CMOS devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.204.1-204.1
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• 2014

스마트폰과 같은 통신기기 및 각종 전자제품에 있어 크기의 축소와 간소화 추세에 따라 인쇄회로기판(PCB)의 초미세회로설계 기술이 요구됨에 따라, 인쇄회로기판과 첨단 전자부품 사이의 접합 신뢰성을 향상시키기 위해 무전해 니켈 도금이 널리 사용되고 있다. 일반적으로, 무전해 Ni도금은 강산, 강염기성 용액을 이용하여 수행되고 있다. 따라서, 공정과정 중에 기판의 손상을 초래하기도 할뿐만 아니라, 환경적으로도 문제시 되고 있다. 본 연구에서는 친환경적 도금공정의 개발을 위해 중성에서 N-(B)무전해 도금을 시행하였다. 중성의 무전해 도금공정은 어떠한 기판을 사용하여도 기판의 손상없이 도금이 가능하다는 장점을 가지고 있고, Boron(B)은 Ni을 비정질화 시키는 물질로 알려져 있다. B가 첨가된 무전해 Ni도금 박막에 있어 B의 영향을 알아보기 위하여 중성조건에서 B를 포함한 DMAB의 첨가량을 조절하였다. Ni-(B) 무전해 도금 시 도금조의 온도는 $40^{\circ}C$로 하였고, 무전해 도금액의 pH는 7(중성)로 유지하였다. Cu Foil기판을 사용하여 DMAB의 양에 따라 성장된 Ni-B무전해 도금 박막의 특성을 분석하기 위해 X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Optical microscope (OM), X-ray Photoelectron Spectroscopy (XPS), X-ray Absorption Spectroscopy (XAS)을 이용하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.236.1-236.1
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• 2014

Compounds of Ga, such as gallium oxide (Ga2O3) and gallium nitride (GaN), are of interest due to its unique properties in semiconductor application. In particular, GaN has the potentially application for optoelectronic device such as light-emitting diodes (LEDs) and laser diodes (LDs) [1]. Nanoparticle is an interesting material due to its unique properties compared to the bulk equivalents. In this report, we develop a synthesizing method for gallium nitride nanoparticle using non-thermal plasma. For gallium source, the gallium is heated by thermal conduction of tungsten boat which is heated by eddy current induced from RF current in antenna. Nitrogen source for nanoparticle synthesis are from inductively coupled plasma with N2 gas. The synthesized nano particles are analyzed using field-emission scanning microscope (FESEM), transmission electron microscope (TEM) and x-ray photoelectron spectroscopy (XPS). The synthesized particles are investigated and discussed in wide range of experiment conditions such as flow rate, pressure and RF power.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.57.2-57.2
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• 2010

대표적인 투명 전극 재료indium tin oxide(ITO)의 경우, 우수한 투과성과 낮은 면저항을 기반으로 차세대 디스플레이용 전극으로 각광 받고 있다. 하지만 제조 단가가 높으며 brittle 하여 유연 디스플레이에 적용이 어려우며 대면적 제조가 어렵다는 단점이 있어 이를 대체할 수 있는 새로운 물질이 필요한 실정이다. 대표적인 후보 물질로는 탄소 육각형이 서로 연결된 관 형태인 탄소나노튜브가 있으며 뛰어난 전기 전도도와 물리적 특성을 투명 전극에 적용하기 위한 연구가 활발히 진행 중이다. 본 연구에서는 탄소나노튜브 투명 전극 제조 시 잔여 분산제 제거 및 doping의 효과를 위해 수행되는 산처리 공정을 하지 않고 투명 전극의 특성을 향상 시키는 연구를 진행하였다. 제작된 박막에 압력을 인가하여 탄소나노튜브 네트워킹의 향상과 두께의 감소를 얻을 수 있었다. 실험에 사용된 탄소나노튜브는 아크 방전 공정으로 합성된 2nm의 single wall 탄소나노튜브이며 이를 분산제인 sodium dodecyl sulfate(SDS)에 분산하여 용액형태로 제작하여 사용하였다. 분산제를 제거하기 위해 탈이온수를 사용하였으며 고분자 mold를 사용하여 압력을 인가하여 그에 따른 전기적, 광학적 변화를 관찰하였다. 제조된SWCNT 박막은 four point probe measurement를 이용하여 sheet resistance를 측정하였고 UV-vis를 이용하여 투과도와 반사도 등의 광학적 특성을 측정하였다. 박막의 표면은 field emission scanning electron microscope (FESEM)과 Atomic force microscope(AFM)를 이용하여 관찰하였다.

• 한국정밀공학회지
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• 제27권12호
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• pp.99-106
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• 2010

Gas turbines operation for power generation increased rapidly since 1990 due to the high efficiency in combined cycle, relatively low construction cost and low emission. But the operation and maintenance cost for gas turbine is high because the expensive superalloy hot gas path parts should be repaired and replaced periodically This study analyzed the initiation and propagation of the crack at the gas turbine blades which are coated with MCrAIY as a bond coat and TBC as a top coat. The sample blades had been serviced at the actual gas turbines for power generation. Total 7 sets of blades were analyzed and they have different EOH(equivalent operation hour). Blades were sectioned and the cracking distribution were measured and analyzed utilizing SEM(scanning electron microscope) and optical microscope. The blades which had 52,000 EOH of operation had cracks at the substrate and the maximum depth was 0.2 mm. Most of the cracks initiated at the boundary layer between TBC and bond coat and propagated down to the bond coat. Once bond coat is cracked, the base metal is exposed to the oxidation condition and undergoes notch effect. Under this environment, the crack branched at the inter-diffusion layer and propagated to the substrate. Critical cracks affecting the blade life were analyzed as those on suction side and platform.