• Electrical & Electronic Materials
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• v.6 no.4
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• pp.366-373
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• 1993

고체구조와 절연파괴의 관계를 확실하게 알아보기 위하여 온도 100[.deg.C]의 실리콘유 내에서 1시간 열처리한 시료에 대해서 직류(DC)와 임펄스 절연파괴특성을 검토했다. 시료의 결정화도는 적외선 흡수와 X선 회절실험 측정방법으로 평가했으며 그리고 시료의 결정립크기와 분상은 시차주사 열량측정을 이용하였다. 실험결과 결정화도의 크기는 서냉, 수냉, 원시료 그리고 급냉시료 순으로 적어짐을 확인하였고 각각 70.23[%], 61.6[%], 56.75[%] 및 34.7[%]를 얻었다. 온도 30, 50[.deg.C]에서 임펄스 절연파괴특성은 결정화도의 감소에 따라 높아지는데 이것은 전자열적파괴를 시사하고 있다. 그리고 온도의 증가에 따라 임펄스 절연파괴강도는 감소되는데 이것은 Frohlich-type의 파괴이론을 제시한다. 또한 직류절연파괴는 저온영역에서 결정화도에 거의 의존하지 않지만 그러나 고온영역에서는 약간 의존한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.172-173
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• 2011

실리콘 태양전지의 공정의 단순화와 효율을 극대화시키기 위하여 전기화학적 방법을 통하여 반사방지막(Anti-Reflection layer)의 선택적 식각공정과 선택적 오믹 전극을 형성하였다. Anti-Reflection coating 층의 식각 공정은 종전의 사진공정을 이용하지 않는 전기-화학적 나노식각을 적용하여 보다 용이한 공정을 연구하였다. 또한 태양전지의 효율을 증대시키기 위하여 전면에서 받은 빛 에너지로 발생된 전자가 전극부분에서 회로로 이동하기 위해 더욱 낮은 저항 값을 가지는 전극 구조가 필요하다. 이를 위해 Ni-P 박막을 형성시킨 전극부분을 열처리함으로써 오믹 접합 특성을 향상시켜 접촉 저항을 현격히 낮출 수 있는 기술을 연구하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.12
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• pp.25-35
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• 2001

In order to analyze the electrical characteristics of complicated thin film transistor-liquid crystal display (TFT-LCD) array circuits, it is indispensible to use simulation programs such as PSPICE and AIM-SPICE. In this paper, we present a systematic method of extracting the input parameters of poly-Si TFT for SPICE simulations. This method was applied to two different types of poly-Si TFTs, fabricated by excimer laser annealing and silicide mediated crystallization methods, and yielded good fitting results to experimental data. Among the SPICE simulators, PSPICE has the graphic user interface feature making the composition of complicated circuits easier. We added successfully a poly-Si TFT device model to the PSPICE simulator, and analyzed easily the electrical characteristics of pixels considering the line RC delay. The results of this work would contribute to efficient simulations of poly-Si TFT-LCD arrays.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.97-102
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• 2012

A hermetically sealed oil transformer is designed by applying expanding function of the tank due to the volume changes of the insulation oil according to the temperature rises. When the insulation oil expands, an increase in the volume of the corrugated fin prevents a pressure rise of the transformer. For a wind turbine transformer, a vegetable-oil-immersed transformer has the advantages of excellent biodegradation and fire-resistant properties like an exceptionally high fire point. When vegetable oil is substituted for mineral oil, however, the maximum winding temperature rises because of the decrease in the internal circulation flow rate resulting from the variations of the oil's physical characteristics, such as density and viscosity. The purpose of this study is to develop a hermetically sealed vegetable oil transformer that can be applied in a wind turbine and to analyze the thermal stability of the active part of the transformer to deal with pressure variations due to the temperature changes. In addition, thermal tests for the vegetable oil transformer have been performed, and the measured values are compared with the analysis results.

• The Optical Journal
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• s.159
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• pp.17-19
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• 2015

스스로 주행하는 지능형 자동차가 천천히 하지만 뚜렷하게 우리에게 다가오고 있다. 실험주행 수준이지만 자동주행 자동차가 실제 도로 위를 누비고 있다. 구글, 테슬라 그리고 애플, 다른 한편에 비엠더블유, 다임러 벤츠 그리고 폭스바겐. 미국 기업과 독일 기업 사이에는 전운마저 감돌기 시작했다. 누가 미래 기술을 선도할 것일까 그리고 이를 통해 다양한 비즈니스의 폭발성을 선점할 것인가를 놓고 실리콘 벨리의 기술 기업과 유럽 대륙의 전통 자동차 기업의 한판 대결을 준비하고 있다. 자동주행 자동차는 기술의 문제로 제한되지 않는다. 자동주행 자동차는 어떻게 교통안전을 담보할 수 있을까, 자동주행 자동차는 새로운 시간과 생활의 가치를 어떻게 제공할 수 있을까, 만약 사고가 발행할 경우 그 책임소재는 어떻게 다툴 것인가, 자동차 보험은 어떻게 재편할 수 있을까 등 무수한 사회문제를 동반하고 있다.

• Resources Recycling
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• v.31 no.6
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• pp.60-65
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• 2022

This study presents the carburization process for recycling sludge, which was formed during silicon wafer machining. The sludge used in the carburization process is a mixture of silicon and silicon carbide (SiC) with iron as an impurity, which originates from the machine. Additionally, the sludge contains cutting oil, a fluid with high viscosity. Therefore, the sludge was dried before carburization to remove organic matter. The dried sludge was washed by acid cleaning to remove the iron impurity and subsequently carburized by heat treatment under vacuum to form the SiC powder. The ratio of silicon to SiC in the sludge was varied depending on the sources and thus carbon content was adjusted by the ratio. With increasing SiC content, the carbon content required for SiC formation increased. It was demonstrated that substoichiometric SiC_x (x<1) was easily formed when the carbon content was insufficient. Therefore, excess carbon is required to obtain a pure SiC phase. Moreover, size reduction by high-energy milling had a beneficial effect on the suppression of SiC_x, forming the pure SiC phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.85-89
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• 1993

Silicone oil exhibits the properies of both organic and inorganic substances and, thus, it has many superior properties such as higher thermal resistance and lower thermal oxidation level when compared to other dielectric liquids. In order to investigate the dielectric characteristics, dielectric liquids of viscosity 1 [cSt] is chosen as the specimen and experiment is performed in the temperature range of 20∼65 [$^{\circ}C$] and frequency range of 30∼1${\times}$10$\^$6/ [Hz] respectively. As a result, the observed linear decrease in dissipation factor at the frequency range below 3 [kHz] is due to the influence of frequency, whereas the increase in dissipation factor at higher frequency range is contributed by electrode's resistance. At a fixed frequency of 30 [kHz], increasing temperature results in higher peak value and wide width of the absorption curve. This is due to the increase in dipole and viscosity. As temperature increases, dipole moment is decreased from 0.98 to 0.64 [debye]. The activation energy which causes the relaxation and loss of dielectric is obtained about 15 [kcal/mole].

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.157-160
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• 2014

We examined and compared the feasibility of vegetable oils with synthetic thermal conductive oils to recover highly purified copper metal from waste jelly-filled communication cables. While polydimethylsiloxane shows relatively poor separation efficiency under entire operating conditions, dibenzyltoluene and waste vegetable oil show the high separation efficiency if the appropriate operating temperature and time were given. By running 50 kg-class equipment with waste vegetable oils, we obtained 100% copper metal recovery with 99.2% purity at $300^{\circ}C$ for 60 min.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.210-214
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• 2002

The crystallization behavior of amorphous silicon (a-Si) film was investigated by using Cu-field aided lateral crystallization (Cu-FALC) process below $450^{\circ}C$. The lateral crystallization was induced from the Cu deposited region outside of pattern toward the Cu-free region inside of the pattern by applying an electric field during heat treatment. As expected, the lateral crystallization toward Cu-free region proceeded from negative toward positive electrode side. The occurrence of Cu-FALC phenomenon was interpreted in terms of dominant diffusing species in the reaction between Cu and Si. Even at the annealing temperature of $350^{\circ}C$, the large dendrite-shaped branches were formed in the crystallized region and the polarity in the lateral crystallization was clearly observed. Consequently, we could successfully crystallize the a-Si at the temperature as low as $350^{\circ}C$ by an electric field of 30 V/cm with fast crystallization velocity of 12 $\mu$m/h.

• Korean Journal of Optics and Photonics
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• v.31 no.5
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• pp.213-217
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• 2020

In this study we report a wet-etching-based fabrication method for adiabatic optical-fiber tapers (OFTs), and describe their adiabaticity and HE₁₁ mode evolution at a wavelength of 1550 nm. The profile of the fabricated system satisfies the adiabaticity properties well, and the far-field pattern from the etched OFT shows that the fundamental HE₁₁ mode is maintained without a higher-order mode coupling throughout the tapers. In addition, the measured far-field pattern agrees well with the simulated result. The proposed adiabatic OFTs can be applied to a number of photonic applications, especially fiber-chip packages. Based on the fabricated adiabatic OFT structures, the optical transmission to the inversely tapered silicon waveguide shows large spatial-dimensional tolerances for 1 dB excess loss of ~60 ㎛ (silicon waveguide angle of 1°) and insertion loss of less than 0.4 dB (silicon waveguide angle of 4°), from the numerical simulation. The proposed adiabatic coupler shows the ultrabroadband coupling efficiency over the O- and C-bands.