• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.385-385
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• 2011

Si 또는 반도체 화합물을 기반으로 한 태양전지의 높은 원재료 가격과 복잡한 공정 등의 문제점들을 해결하기 위한 방안으로 반도체성 고분자인 Poly(3-hexylthiophene)(P3HT)과 C60 유도체인 PCBM을 광활성 층으로 이용하여 유기 태양전지(Organic Solar Cell, OSC)를 제작하였다. 하지만 상대적으로 낮은 효율을 갖는 OSC의 단점을 해결하기 위해서 유기물 자체가 갖고 있는 광 안정성, 낮은 전하 이동도 및 광 에너지 흡수대 등의 문제점들의 해결 방안들이 제시되고 있다. 본 연구에서는 광활성 층을 사용한 유기 태양전지의 특성에서 후열처리에 따른 유기 태양전지의 전기적 및 구조적, 광학적인 특성들이 소자의 효율에 끼치는 영향에 대해 분석하였다. 후열 처리 온도에 따른 광활성 층의 구조적인 특성을 분석하기 위해 EFM 이미지와 XRD패턴을 측정하였는데 열처리 후 박막의 전기적인 포텐셜과 결정성 향상의 유기 태양전지의 효율향상에 기여함을 알 수 있었다. 또한 임피던스 분석 장치를 이용해 후열 처리에 따른 소자의 Resistance, Capacitance, I-V 곡선들을 분석한 결과 최적의 조건에서 열처리된 광활성 층은 전하들의 이동을 조절하여 소자 내에서 Capacitance를 증가시키는 것 뿐만 아니라 전극과 유기물 층 사이의 계면 특성을 향상시킴으로써, 소자의 효율을 증가시키는 원인으로 작용함을 확인 하였다.

• Analytical Science and Technology
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• v.13 no.6
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• pp.705-711
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• 2000

We have studied the structural characterization, surface morphology and electrical properties for boron dopped polyacene anode material from phenolic resin for lithium secondary battery. The boron dopped anode material were characterized as boron contents of 5, 10, 15 and 20%, respectively. From the X-ray results, the all kinds of compounds were observed for the diffraction patterns for typical amorphous carbons. The SEM morphology showed formation of semi spherical granule for the boron dopped compounds. As the result of the electrical charge/discharge and impedance data, the 10 and 15% boron dopped materials showed good properties on the ions and electron transfer effect of battery.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.153-161
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• 1993

Cathodic oxygen reduction kinetics on $La_{0.9}Sr_{0.1}MnO_3$ electrode have been examined at $700-900^{\circ}C$ under various oxygen partial pressures. AC impedance and current interruption techniques were employed for the determination of charge transfer resistances for electrochemical oxygen reduction. The $R_{ct}$ values obtained from two different methods were very close each other for $La_{0.9}Sr_{0.1}MnO_3$ electrode. Activation energy for the electrochemical oxygen reduction was found to be 174kJ/mol under atmospheric oxygen pressure. $R_{ct}$ measurements as a function of oxygen partial pressure indicate that the rate-determining step for the electrochemical oxygen reduction on $La_{0.9}Sr_{0.1}MnO_3$ electrode is the charge transfer process.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.1-4
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• 1999

A lithium ion battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key factor of the secondary battery system, that has been obtained during the process of the development of a polymer type lithium battery. As a successful result of the solid polymer electrolyte. The ionic conductivity of the solid polymer electrolyte, which is composed of polyacrylonitrile and $LiClO_4\;with\; Al_2O_3$ dissolved as the supporting electrolyte, has been confirmed to be $2.3\times10^{-4} S/cm$ at room temperature.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.4
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• pp.221-226
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.55-59
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• 1998

The water absorption in protective coatings, which may greatly influence the durability of these coatings, was studied using quartz crystal microbalance and electrochemical impedance technique. The water absorption in protective coatings and the change of coating capacitance with concentration of electrolyte were measured. The water absorption in coatings seems to be driven by osmotic pressure, and larger amount of water was absorbed in thinner coatings at initial stage of absorption. The amount of water absorbed in coatings changed with the type and crosslinking density of resin used in coating formulation. When water absorption and desorption of coating occured by exposing the coatings to electrolyte solutions of different concentration, increase in impedance caused by desorption of water was found to be higher in the case of thinner film.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.3
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• pp.73-79
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• 2012

A counterpoise is commonly employed in grounding systems installing near the ground surface of low resistivity soils and radial-type counterpoises are used in the limited space. Recently some studies on the evaluation of ground impedance of paralleling ground electrodes have carried out, but the data for providing the frequency-dependent ground impedances considering potential interferences are not yet sufficient. In order to provide the information about the design of grounding systems for surge protection, the simulations of the frequency-dependent ground impedance of various shaped counterpoises are carried out by using the distributed parameter circuit model including the effect of potential interferences. This paper presents the theoretical simulations and actual experiments of the frequency-dependent ground impedance of paralleling and 3 or 4-arms star counterpoises. The accuracy of the simulation methodology is examined by the comparison with the measured results, and the results show a good agreement between the simulation and the experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.77-81
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• 2009

Air-gap was introduced to suppress the saturation of the iron core comprising the flux-lock type superconducting fault current limiter (SFCL) with parallel connection of two coils. However, the air-gap makes the impedance of this SFCL decreased and can result in unusefulness of the SFCL. To analyze the current limiting characteristics of the SFCL with the air-gap, the experimental circuit for short-circuit test was constructed. Through the comparison with the current limiting characteristics of the SFCL without air-gap, the merit and the demerit of the flux-lock type SFCL with the air-gap were discussed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.367-370
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• 2008

In this paper, the effects of the position and the angle of the auxiliary probes on the measurements of the low frequency ground impedance with the fall-of-potential method are described iud the testing techniques to minimize the measuring errors are proposed. The fall-of-pot ential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position and angle of auxiliary probes. In order to analyze the characteristics of ground impedance due to the location of the potential probe, ground impedances were measured in case that the distance of current probe was fixed at 50[m] and the distance of potential probe was located from 10[m] to 50[m]. Also, the potential robe was located at 30[$^{\circ}$], 40[$^{\circ}$], 60[$^{\circ}$], 90[$^{\circ}$], and 180[$^{\circ}$]. The results could be help to determine the location of potential probe when the ground impedance was measured at grounding system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.287-287
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• 2008

HTS-케이블은 구리도체 대신 고온초전도도체를 사용하여 저항이 0이 되는 초전도현상을 이용하여 대용량 전력수송이 가능한 전력케이블로서 대도시의 전력부하 집중문제를 해결할 수 있는 환경 친화적 전력케이블이다. 최근 고온초전도선재의 고임계전류밀도화 및 장척화에 힘입어 HTS-케이블의 실용화를 목표로 경제성이 있는 전력케이블을 개발하려는 움직임뿐만 아니라 실증시험 등 활발한 연구가 진행 중이다. 그러나 초전도전력케이블에서 발생되는 교류손실은 케이블의 효율을 저하시킬 뿐만 아니라 냉동기비용 증가로 인한 기존 케이블과의 가격경쟁에서 경제성을 저하시키는 주된 요인으로 작용하기 때문에 이의 상용화에 앞서 교류손실에 대한 정확한 규명이 되어야 하며 또한 실계통 투입 시 중요한 선로임피던스에 대한 정확한 규명도 필요하다. 본 논문에서는 실제 한전 주관으로 고창시험장에 설치된 배전급 22.9 kV, 100 m, 50 MVA급 3 상 HTS-케이블에 대한 통전특성을 규명하기 위하여 먼저 HTS-케이블의 DC 통전특성을 조사하였다. 또한 3상평형운전상태에서 AC 통전특성(인덕턴스 및 교류손실)을 실험적으로 조사하였으며 5m-케이블에서 측정된 결과와 비교 검토하였다.