• 한국기계가공학회지
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• 제8권3호
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• pp.38-45
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• 2009

Recently, LCD Backlight Unit is being replaced from cold cathode fluorescent lamp(CCFL) to external electrode fluorescent lamp(EEFL) because the EEFL has high energy efficiency and long life. Also, it can reduce energy consumption and weight. So far, external electrode ring for EEFL is produced by sheet metal press forming process. Therefore it had low precision and much material loss. To solve these problems, Multi-Forming process that has five step forming process was invented. However, low productivity is another barrier. Product speed that is controlled by the rotational speed cannot be increased due to the unsatisfied design specification. The reason is that the gap between rolled two edge parts of the sheet plate is tightly inspected. Regarding this factor, the understanding of forming behavior to each process is inevitable. This paper describes the CAE analysis of the multi-forming process by PAM-STAMP.

• 대한전기학회논문지
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• 제34권6호
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• pp.244-252
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• 1985

A model is presented to explain charging phenomena into the oxide layer when a metal-oxide-silicon(MOS) capacitor is driven by a large amplitude and high frequency ac signal sufficient to produce avalanche injection in the silicon. During avalanche, minority carriers are injected. It is assumed that some of these minority carriers attain sufficient energy to surmount the potential barrier at the interface, and then inter the oxide. Measurements of C-V curves are made for the MOS capacitor with p-type silicon substrates before and after avalanche injection. This paper studies how charging in the oxide and the interface depends on oxide properties. It is concluded that this charging effect is related to the presence of water in the oxide.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2004-2006
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• 2005

트렌치 애노드 컨택을 설계하여 순방향 전압강하를 감소시키는 GaN 쇼트키 장벽 다이오드를 제안하였다. 애노드 내부에 트렌치를 설계하여 제안된 소자의 표면 애노드 컨택은 메탈 일 함수(metal work function)가 높은 Pt와 형성되며, 트렌치 애노드 컨택은 메탈 일 함수가 낮은 Au와 형성된다. 제안된 소자의 전기적 특성을 검증하기 위하여 2차원 수치 해석 시뮬레이션을 수행하였고, AlGaN/GaN 혜테로 접합 구조 위에 제작 및 측정하였다. 제안된 소자는 복잡한 공정 추가 없이 제작되며 $100A/cm^2$에서의 순방향 전압 강하는 0.73V로 기존 소자의 1.25V보다 우수한 특성을 보였다. 제안된 소자의 온 저항은 $1.58m{\Omega}cm^2$로 기존 소자의 온 저항 $8.20m{\Omega}cm^2$ 보다 낮은 장점을 가진다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.87-88
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• 2006

Ceramic-Metal Functionally Graded Materials (FGM) are of great interest for application as Thermal Barrier Coating (TBC) or Wear Resistant Coating (WRC). Spark Plasma Sintering (SPS) is a promising techniques for time-saving consolidation of laminated/graduated powder systems: SPS is a pressure-assisted electrical sintering method which directly applies a pulsed DC current as heat source. In the present work, production of $Al_2O_3-Ni$ FGMs by means of Spark Plasma Sintering is considered; effect of sintering condition on density, hardness and fracture toughness is studied. Problems correlated to this new processing technology are discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.429-429
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• 2010

TFT 제조 방법 중 LTPS (Low Temperature Polycrystalline Silicon)는 저온과 저비용 등의 이점으로 인하여 flat panel display 제작에 널리 사용된다. 이동도와 전류 점멸비 등에서 이점을 가지는 ELA(Excimer Laser Annealing)가 널리 사용되고 있지만, 이 방법은 uniformity 등의 문제점을 가지고 있다. 이를 극복하기 위한 방법으로 MICC(Metal Induced Capping Crystallization)이 사용되고 있다. 이 방법은 $SiN_x$, $SiO_2$, SiON등의 capping layer를 diffusion barrier로 위치시키고, Ni 등의 금속을 capping layer에 도핑 한 뒤, 다시 한번 열처리를 통하여 a-Si에 Ni을 확산시키킨다. a-Si 층에 도달한 Ni들이 seed로 작용하여 Grain size가 매우 큰 film을 제작할 수 있다. 채널의 grain size가 클 경우 grain boundary에 의한 캐리어 scattering을 줄일 수 있기 때문에 MIC 방법을 사용하였음에도 ELA에 버금가는 소자의 성능과 안정성을 얻을 수있었다. 본 연구에서는 large grain TFT의 Gate bias stress에 따른 소자의 안정성 측정 및 분석에 목표를 두었다.

• 대한금속재료학회지
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• 제48권8호
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• pp.775-779
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• 2010

Functionally graded materials (FGM) of PSZ/NiCrAlY on Inconel substrate were fabricated by detonation gun spraying method. A thick ceramic layer generally has a high thermal barrier effect however, because failure often occurs, the use of an FGM layer gives an advantage in thermal property. During the thermal shock test, micro fracture processes were detected by the AE method. Also, the thermal shock test was performed for NFGM, FGM and the changed FGM in the layered composition profile. It was found through AE testing and the observation of fracture surface that FGM was superior to NFGM in thermal shock properties. The linear or metal-rich type FGM in composition profile had the best resisting property among the FGM. It was found that the controlled composition profile of the graded layers had better thermal properties.

• Bulletin of the Korean Chemical Society
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• 제15권8호
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• pp.658-662
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• 1994

Ab initio and extended Huckel calculations have been applied to discuss the electronic structure, ring inversion barrier, and geometry of the $Cp_2TiS_3$ compound. The deformation of four membered ring in the planar geometry is originated from a second-order Jahn-Teller distortion due to the small energy gap between HOMO and LUMO on the basis of extended Huckel calculations. The puckered $C_s$ geometry is stabilized by the interaction of the $x^2-y^2$ metal orbital with the hybrid orbital in sulfur. Ab initio calculations have been carried out to explore the ring inversion process for the model $Cl_2TiS_3$ compound. We have optimized $C_s$ and $C_{2v}$ structures of the model compound at the RHF level. The energy barriers for the ring inversion are sensitive to the used basis set. With 4-31$G^*$ for the Cl and S ligands, the barriers are computed to be 8.41 kcal/mol at MP2 and 8.02 kcal/mol at MP4 level.

• Journal of Electrochemical Science and Technology
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• 제12권3호
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• pp.308-316
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• 2021

In this work, we report synthesis, characterization and corrosion inhibition properties of cationic thiol surfactant-capped silver (SC-Ag-NPs) and gold (SC-Au-NPs) nanoparticles. SC-Ag-NPs and SC-Au-NPs were characterized using regular techniques include TEM. Corrosion study was carried out using carbon steel (CS) in 3.5% NaCl aqueous solution and characterized using multiple electrochemical techniques. Our results suggest that the paint containing SC-Ag-NPs and SC-Au-NPs endow efficient corrosion protection to the CS. Especially, SC-Au-NPs based paint form a stronger barrier between the metal and the corrosive ions, leading to better inhibition properties.

• 한국지반환경공학회 논문집
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• 제5권2호
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• pp.23-31
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• 2004

본 연구에서는 침출수 차수재에 Zero Valent Iron (ZVI)를 포함 시켰을 경우, ZVI 함량과 pH에 따른 TCE, 6가 크롬, 질산성질소의 제거능의 변화를 살피고, 반응이 끝난 후 철과 벤토나이트 표면의 철 산화물을 라만 분광기를 통해서 알아보고자 하였다. ZVI의 함량을 중량비로 벤토나이트의 0, 3, 6, 10, 13, 16, 20, 30, 100 w/w% 로 맞춘 9가지의 샘플을 pH7의 완충 용액을 사용했을 경우와 완충 용액을 사용하지 않을 경우 두 가지로 나누어서 실험하였다. Kinetic test 결과, pH7의 완충 용액을 사용하였을 때가 사용하였지 않았을 때보다 TCE의 경우 330시간에서 300시간으로, 6가 크롬의 경우 20시간에서 4시간으로, 질산성질소는 140시간에서 5시간으로 제거 속도가 빨라졌다. 모든 오염물질의 경우 ZVI 함량이 증가할수록 제거 효율이 높아졌으며, pH 7의 완충 용액을 사용하였을 경우 제거 효율도 더 높아지는 것을 볼 수 있었다. 반응 후 철과 벤토나이트의 표면을 라만 분광기를 이용하여 분석한 결과 여러 가지 철산화물이 확인되었다. 이러한 철산화물은 좋은 흡착제의 역할을 할 수 있으며, 이 중 magnetite는 장기간 동안 오염물질의 제거 성능을 유지시켜 줄 수 있다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.179-184
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• 2016

In recent years, the on-resistance, power loss and cell density of Si power devices have not exhibited significant improvements, and performance is approaching the material limits. GaN is considered an attractive material for future high-power applications because of the wide band-gap, large breakdown field, high electron mobility, high switching speed and low on-resistance. Here we report on the Ohmic contact resistance and reverse-bias characteristics of AlGaN/GaN Schottky barrier diodes with and without annealing. Annealing in oxygen at $500^{\circ}C$ resulted in an increase in the breakdown voltage from 641 to 1,172 V for devices with an anode-cathode separation of $20{\mu}m$. However, these annealing conditions also resulted in an increase in the contact resistance of $0.183{\Omega}-mm$, which is attributed to oxidation of the metal contacts. Auger electron spectroscopy revealed diffusion of oxygen and Au into the AlGaN and GaN layers following annealing. The improved reverse-bias characteristics following annealing in oxygen are attributed to passivation of dangling bonds and plasma damage due to interactions between oxygen and GaN/AlGaN. Thermal annealing is therefore useful during the fabrication of high-voltage GaN devices, but the effects on the Ohmic contact resistance should be considered.