• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.588-594
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• 2013

Under the condition of Baader aging, the chemical composition variation and the influence of transformer oil aging on electrical properties such as dielectric loss factor and physic-chemical properties such as interfacial tension were studied in the aging precess. Moreover, the correlation between hydrogenated transformer oil electrical and physic-chemical properties and its chemical composition variation were also investigated. The results show that these parameters of physic-chemical and electrical properties of hydrogenated transformer oil relate to each other and have closed correlation with chemical composition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1912-1914
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• 2005

The electrical, chemical and mechanical characteristics in transformer insulations are changed due to thermal stress. It is known that characteristics of transformer insulations is deteriorated such as decrease of dielectric strength, deterioration of dielectric constant and tensile strength of paper as transformer oil and paper are aged by thermal stress. Furthermore, chemical characteristics of them are deteriorated as like increment of moisture contents and dissolved by-products in oil, etc. In this paper we have been investigated chemical characteristics of transformer by accelerated thermal aging. For this working we have made experimental test cell and aged at a temperature up to $140^{\circ}C$ for 500 hours. The oil-paper insulation samples have been measured at intervals of 100 hours. For analysis we used Karl-Fisher titration method and high performance liquid chromatography (HPLC).

• 전기전자학회논문지
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• 제22권2호
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• pp.344-349
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• 2018

AlGaN/GaN HEMT를 제작하여 상온에서 $-178^{\circ}C$의 저온에 이르기까지 트랜지스터의 전기적인 특성 변화를 연구하였다. 상온에서 264 mA/mm를 나타내던 게이트 길이 $2{\mu}m$인 HEMT의 드레인 전류는 온도의 감소에 따라 변화하여 $-108^{\circ}C$의 온도에서 388 mA/mm로 47%의 증가를 나타냈으며 최대 트랜스컨덕턴스는 121 mS/mm로 부터 183 mS/mm로 증가하였다. 또한 $-178^{\circ}C$의 온도에 이르기까지 -0.39 V의 문턱전압 변화를 보였다. 이러한 변화는 주로 상온에서부터 $-108^{\circ}C$의 온도에서 나타나고 있으며 온도감소에 따른 $720{\Omega}/sq.$ 로부터 $300{\Omega}/sq.$로 감소하는 면저항의 변화와 함께하고 있다.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2155-2161
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• 2013

Composite materials of mesoporous carbon and carbon nanotubes were synthesized using Ni, Co and Pd-loaded CMK3 via a catalytic reaction of methane and $CO_2$. The CNTs grew from the pores of the mesoporous carbon supports, and they were attached tightly to the CMK3 surface in a densely tangled shape. The CNT/CMK3 composite showed both non-graphitic mesoporous structures, and graphitic characteristics originating from the MWCNTS grown in the pores of CMK3. The electrochemical properties of the materials were characterized by their electrorheological effects and cyclic voltammetry. The CNTs/CMK3 composites showed high electrical conductivity and current density. The CNT/CMK3 or KOH-modified CNT/CMK3 particles were incorporated in a PMMA matrix to improve the thermal and electrical conductivity. Even higher thermal conductivity was achieved by the addition of KOH-modified CNT/CMK3 particles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.25-26
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• 2011

In this paper, we investigated the effect of various annealing processes on the electrical characteristics of oxide thin film transistors (TFTs). When we annealed the TFT devices before and after source/drain (S/D) process, we could observe the different electrical characteristics of oxide TFTs. When we annealed the TFTs after deposition of transparent indium zinc oxide S/D electrodes, the annealing process decreased the contact resistance but increased the resistivity of S/D electrodes. The field effect mobility, subthreshold slope and threshold voltage of the oxide TFTs annealed before and after S/D process were 5.83 and 4.47 $cm^2$/Vs, 1.20 and 0.82 V/dec, and 3.92 and 8.33 V respectively. To analyze the differences, we measured the contact resistances and the carrier concentrations using transfer length method (TLM) and Hall measurement.

• 반도체디스플레이기술학회지
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• 제10권1호
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• pp.51-55
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• 2011

The surface passivation is one of the important methods that can improve the efficiency of solar cells and can be classified into two methods: wet-chemical passivation and film passivation. In this paper, chemical HF treatment were employed for the passivation of n-type silicon wafers and their effects were studied. To investigate film passivation effects, the silicon nitride films were also deposited by PECVD (plasma-enhanced chemical vapor deposition) on n-type silicon wafers treated with chemical HF. The minority carrier lifetime measurements were used for evaluation of the passivation characteristics in the all experiments steps. We confirmed that the minority carrier lifetime was improved with chemical HF treatment due to passivation effects by H-termination.

• 한국전기전자재료학회논문지
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• 제35권1호
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• pp.37-43
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• 2022

In this study, we investigated the optical, electrical and exothermic characteristics of ITO/Ag/ITO multilayer structures prepared with various Ag thicknesses on quartz and PI substrates. The transparent conducting properties of the ITO/Ag/ITO multilayer films depended on the thickness of the mid-layer metal film. The ITO/Ag (14 nm)/ITO showed the highest Haccke's figure of merit (FOM) of approximately 19.3×10^-3 Ω^-1. In addition, the exothermic property depended on the substrate. For an applied voltage of 3.7 V, the ITO/Ag (14 nm)/ITO multilayers on quartz and PI substrates were heated up to 110℃ and 200℃, respectively. The bending tests demonstrated a comparable flexibility of the ITO/Ag/IT multilayer to other transparent electrodes, indicating the potential of ITO/Ag/ITO multilayer as a flexible transparent conducting heater.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.109-112
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• 2001

Water-Electrolyzed gas is a mixed gas of the constant volume ratio 2:1 of Hydrogen and Oxygen gained from electrolyzed water, and it has better characteristics in the field of economy, efficiency of energy, and environmental intimacy than acetylene gas and LPG (Liquefied Petroleum Gas) used for existing gas welding equipment. So studies of Water-Electrolyzed gas are activity in progress nowaday, and commercially used as a source of thermal energy for gas welding in the industry. The object of this paper is getting a V-I characteristic of Hydrogen-Oxygen Gas Generator using DC source. First, chemical analysis of electrolysis is conducted and the relation of electrical energy and then chemical energy is investigated through the faraday's laws.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1117-1119
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• 1995

Fluoroplastics have been used widely for chemical or electrical facility materials and lubricable engineering structural materials because they have the superior characteristics such as thermal stability, chemical stability, solid lubricity, arc resistance, wearable durability and good sealing property. In this study, PTFE composite materials for the insolation parts of high voltage and current breaker were investigated and estimated.

• Carbon letters
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• 제14권1호
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• pp.1-13
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• 2013

Carbon nanotubes (CNTs) are increasingly attracting scientific and industrial interest because of their outstanding characteristics, such as a high Young's modulus and tensile strength, low density, and excellent electrical and thermal properties. The incorporation of CNTs into polymer matrices greatly improves the electrical, thermal, and mechanical properties of the materials. Surface modification of CNTs can improve their processibility and dispersion within the composites. This paper aims to review the surface modification of CNTs, processing technologies, and mechanical and electrical properties of CNT-based epoxy composites.