• Proceedings of the KIPE Conference
• /
• 2012.11a
• /
• pp.1-2
• /
• 2012

본 논문에서는 직류배전의 보호를 위한 고장전류제한기술을 제안한다. 제안된 전류제한기는 PWM스위칭 방식으로 동작하며 차동증폭기, 비교기, MOSFET스위치와 게이트드라이버로 구성되어 있다. 전류제한기는 부하 측의 단락사고나 돌입전류를 제어하기 위한 목적으로 직류리액터 $L_f$에 흐르는 전류를 센싱하여 기준전류 $L_{ref}$보다 높게 흐르려는 경우 MOSFET은 ON/OFF스위칭 하여 기준전류 $L_{ref}$이상으로 흐르지 못하게 함으로써 과전류가 흐르는 것을 방지한다. 제안된 전류제한기의 성능을 실험을 통하여 검증 한다.

• Progress in Superconductivity and Cryogenics
• /
• v.7 no.4
• /
• pp.14-19
• /
• 2005

A transient numerical simulation was conducted to have variation of temperature on an element of resistive Superconducting Fault Current Limiter (SFCL) under quench condition. It is very important engineering information for an optimum design of cryogenic system for cooling of a resistive SFCL element. A bifilar coil for resistive SFCL for 10 MVA system was incorporated as a model in this numerical study. From the numerical simulation result, it was found that the averaged temperature on the shunt and Bi-2212 element at 500 kW, 100 ms was 711.1 K and 198.4 K respectively. The temperature variation with the change of the hot-spot size and time is also obtained. The maximum temperature was continuously increased in all cases until the hot-spot stops at 100ms and it was going down after then. Such as, the details of temperature distribution on the SFCL element obtained from this numerical study and it should be very valuable information on the decision of the cooling capacity of cryogenic system.

• 전기의세계
• /
• v.24 no.1
• /
• pp.63-69
• /
• 1975

This study investigated the characteristics of fatigue breakdown caused by the impulse voltage of heat treated polyethylene cables through fault currents. This study attempted to obtain the badic data on the insulation design by the repeated load of impulse voltage wave zone (1*40.mu.s) on heat treated polyethylene cables. Besides this study also analysed the data involving their durability by means of the Weibull distribution. An analysis of the breakdown characteristics based upon the repeated load of impulse voltage has revealed that worn out deteriorative breakdown existed at a high voltage near the initial breakdown voltage, and that random breakdown was discovered at a voltage somewhat lower than the initial breakdown voltage. These phenomena were more remarkable especially in the case of the higher temperature treated cables.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.566-568
• /
• 2004

최근 한국전력은 중국, 인도 둥 동남아시아 지역을 주요대상으로 자체개발한 종합배전자동화시스템을 수출하고자 활발하게 접촉하고 있다. 이들 대부분 수출대상 주요국가의 배전계통이 비접지로 운영하고 있어 배전계통 운영자의 공통된 관심사가 지락고장이 발생한 경우에 고장처리 방법이다. 비접지 계통은 단락고장의 경우 고장전류가 커 쉽게 고장구간 탐색이 용이하지만, 지락고장의 경우 고장전류가 매우 적어 배전자동화시스템에서 지원하는 고장처리 기능을 수행하기에 곤란하다. 따라서 해외시장의 기술적 우위확보와 종합배전자동화 시스템의 다목적 기능을 수행하고자 연구를 시작하였다. 지락고장이 발생하였을 때의 각종 파라메타를 중심으로 검토하였으며, 영상전압과 영상전류의 위상을 비교하여 고장구간 탐색기법을 제시하였다. 현재 연구결과를 바탕으로 현장실증시험이 진행되고 있다.

• Journal of Communications and Networks
• /
• v.15 no.5
• /
• pp.464-468
• /
• 2013

The widespread use of cryptographic technologies is complicated by inconsistencies and duplication in the key management systems supporting their applications. The proliferation of key management systems or protocols also results in higher operational and infrastructure costs, and fails in interoperability. Thus, it is essential to realize key management interoperability between different and heterogeneous cryptosystems. This paper presents a practical and separable key management system for heterogeneous public-key cryptosystems. We achieve the interoperability between different cryptosystems via cryptography approaches rather than communication protocols. With our scheme, each client can freely use any kind of cryptosystemthat it likes. The proposed scheme has two advantages over the key management interoperability protocol introduced by the organization for the advancement of structured information standards. One is that all the related operations do not involve the communication protocol and thus no special restrictions are taken on the client devices. The other is that the proposed scheme does not suffer from single-point fault and bottleneck problems.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.512-514
• /
• 2002

우리나라의 지중배전선로는 가공선의 정비 차원에서 지중케이블로 공급함으로써 시작되었으며, 지금은 변전소 인출개소와 택지개발 지역에 신규공급용으로 주로 설치되고 있다. 지중배전선로는 매년 약 7%의 증가율을 보여주고 있으며 2001년말 기준으로 케이블긍장이 16,301(C-km)로 약9.4%의 지중화율을 나타내고 있다. 선로가 증가함에 따라 고장의 발생이 광역정전등 점차 많은 문제점을 내포하고 있다. 지중배전선로의 고장은 주로 케이블에서의 외상과 열화가 주요인으로 이는 환경적인 영향과 제작 시공 및 유지관리면에서의 미흡에 의한 것으로 효과적인 관리를 위해서는 지하매설물종합관리기관 설립 등의 제도적 도입과 선로제작과 시공품질의 향상을 유도하기 위한 계약 제도의 보완 및 선로의 중요도와 경제성에 따른 차별화된 관리 방법과 선로고장시 정확한 data 보고관리의 여건 마련과 아울러 정확한 선로 이력 database화 등의 체계적인 선진 예방보수 기법의 도입이 요구된다.

• The Journal of Information Technology
• /
• v.10 no.2
• /
• pp.47-64
• /
• 2007

Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. Accurate predictions of software release times, and estimation of the reliability and availability of a software product require quantification of a critical element of the software testing process : test coverage. This model called enhanced non-homogeneous poission process(ENHPP). In this paper, exponential coverage and S-coverage model was reviewed, proposes the exponentiated exponential coverage reliability model, which maked out efficiency substituted for gamma and Weibull model(2 parameter shape illustrated by Gupta and Kundu(2001). In this analysis of software failure data, algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE statistics for the sake of efficient model, was employed.

• Journal of Korean Elementary Science Education
• /
• v.21 no.2
• /
• pp.241-252
• /
• 2002

Field learning have not well performed in elementary school for various reasons, in spite of the benefits of field study. Absence of suitable geological field courses for elementary science education is one of several reasons The purpose of this study is to develop learning materials for the field geology in Hampyeong region and apply them to the geological related units for elementary science education. The 5 observation sites for the field geology learning in study area include various rocks and geological structure such as granite, gneiss, conglomerate, sandstone, mudstone, plant fossil, fold, fault and weathering phenomenon changing rocks to soil. This study area is suitable place for the field geology learning of elementary science education in Kwangju and Chonnam province because of convenience access, fresh outcrops and distribution of various geological learning materials as rocks and structure.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.123-124
• /
• 2008

전력품질에 대한 관심이 증가함에 따라 고객의 요구를 충족시키기 위하여 전력품질에 영향을 미치는 요소에 대한 분석 및 효율적인 대책 마련이 요구되고 있다. 따라서, 본 논문에서는 전력품질의 주문제중의 하나인 sag에 대하여 분석하였다. EMTP를 이용하여 한전의 실 배전계통을 모델링하여 고장으로 인한 sag를 모의하였다. 다양한 고장발생 조건에 대하여 모의하여, 고장으로 인한 sag 발생 시 배전계통에서 상하단 상호간에 미치는 영향에 대하여 분석하였다. 그 결과 평형 및 불평형 고장에 따라 그 영향이 달리 나타남을 확인할 수 있었다.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.424-425
• /
• 2008

This paper presents application of RCM(Reliability Centered Maintenance) in waterworks system. The reliability-based probability model for predicting the failure probability is established and FTA(Fault Tree Analysis) is proposed to considering RCM. To calculate failure probability, Weibull distribution is usually used due to age related reliability. FTA is an engineering analysis which is using logic symbols. The real historical data of CMMS(Computerized Maintenance Management System) make full use of case study for waterworks system. Consequently, the RCM would be likely to permit utilities to reduce overall costs in maintenance and improve the total benefit.