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Carbon Black-PVC와 Carbon Black-HDPE 복합재료의 전기적 성질
정상기,노시태,임승순,Jeong, Sang-Gi,No, Si-Tae,Im, Seung-Sun 한국섬유공학회 1991 한국섬유공학회지 Vol.28 No.12
Electrical conductive PVC and HDPE composites were prepared by melt compounding method with electrical conductive carbon black. The electrical and mechanical properties of carbon black composites were affected by the particle size, surface area, density, aggregation morphology and dispersion state of carbon black, According to the carbon black contents, the composites have shown the behaviors of insulator, semiconductor and conductor. The percolation threshold of the carbon black composite was examined. From the temperature dependence of conductivity for the composites, we found that Carbon Black-PVC composites were very stable and reproducible to the temperature changes. Carbon Slack-HDPE composites have shown a PTC(positive temperature coefficient of resistively) effect which has a sudden resistively increase by thermal expansion of polymer at melting region. To prevent a NTC(negative temperature coefficient of resistively) effect and improve reproducibility of conductivity, the chemical crosslinking was accomplished.
객체지향모델를 이용한 경량전철 시스템의 성능 시뮬레이션
정상기,정락교,한석윤,Jeong, Sang-Gi,Jeong, Rak-Gyo,Han, Seok-Yun 한국시스템엔지니어링협회 2004 시스템엔지니어링워크숍 Vol.4 No.-
Most rail system related simulations currently used are designed to simulate only one discipline system. This obviously assunes the other discipline system are running regularly not being affected by the system being simulated. In this paper a multi discipline simulator is proposed and its design concept is presented.A multi discipline simulator is the simultor in which major subsystems with different technical discipline are simulated simultaneously. The advantage of the simulator is in that it makes it possible to analyze the systems behavior while other discipline system vary. With this we can identify the possible to analyze the systems ehavior find their solutions. A proto type simulator has bee developed using object oriented programming. Object concept was judged best suitable to model the various multi-discipline self-controlling railway subsystems. It was applied to the target system, which is under development by the Korea Railroad Research institute. The test results show it is very useful in design verification. It could also be a good tool in research and development work to make to improe the system.
정상기(Sang-Gi Chung),정락교(Rag-Kyo Jeong),김형철(Hyung-Chul Kim) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.11
전기철도의 DC 급전시스템에서 레일전위상승 값을 분석하는 알고리즘을 제시한다. 레일전위는 대지로의 누설저항에 의해서 상승하게 된다. 이 누설저항이 삽입된 급전시스템 등가회로는 노드전압 회로 분석방법에 의해 직접 해석이 되지 않는다. 메쉬전류 회로분석 방법에 의해서 해석될 수 있는데, 이 메쉬전류 회로해석 방법의 적용에도 문제가 있다. 그것은 철도부하가 저항으로 주어지지 않고 파워(power)로 주어지므로 반복해석(iteration) 방법이 사용되어야 하고, 이 반복해석 방법은 적정한 초기값을 요구하는데 컴퓨터를 이용한 해석 시 메쉬전류의 초기값이 일정한 방법으로 찾아지지 않기 때문이다. 본문에서는 노드전압 회로해석 방법을 2번 사용함으로써 레일전위 상승을 해석하는 알고리즘을 제시한다. 또한 알고리즘의 검증하기 위하여 EMTP-RV의 해석결과와 비교 분석하였다.
정상기(Sang-Gi Chung),정락교(Rag-Kyo Jeong),김백현(Baek-Hyun Kim) 대한전기학회 2011 전기학회논문지 Vol.60 No.1
A PRT vehicle’s control method is presented in this paper. In the asynchronous vehicle control system, vehicles follow their leading vehicles. Leading vehicles are defined differently among the different types of track. The main topic of this paper is to present a method to define the leading vehicle among different types of track and the calculation algorithm of the safety length the following vehicle must maintain. Simulation program is developed using the algorithm and the results of the test run are presented. An asynchronous PRT vehicle control algorithm was presented by Szillat in the paper “A low level PRT Microsimulation, Dissertation, University of Bristol, 2001”. But it is different from the algorithm in this paper. In the algorithm proposed by Markus, vehicles in the merging track are controlled synchronously, and its safety distance between the leading and the following car is evaluated after the establishment of the complicated future time-location table instead of simple equations proposed in this paper.
정상기(Sang-Gi Chung),정락교(Rag-Gyo Jeong),이성혁(Sung-Hyeok Lee),김연수(Yun-Su Kim),조홍식(Hong-Sik Cho) 한국철도학회 2004 철도저널 Vol.7 No.4
In urban rail transit systems, ground faults in the DC traction power supply system are currently detected by the potential relay, 64P. Though it detects the fault it cannot identify the faulted region and therefore the faulted region could not be isolated properly. Therefore it could cause a power loss of the trains running on the healthy regions and the safety of the passengers in the trains could be affected adversely. Two new ground fault protective relay schemes that can identify the faulted region are presented in this paper. A current limiting device, called Device X, is newly introduced in both system, which enables large amount of ground fault current flow upon the positive line to ground fault. One type of the relaying schemes is called directional and differential ground fault protective relay which uses the current differential scheme in detecting the fault and uses the permissive signal from neighboring substation to identify the faulted region correctly. The other is called ground over current protective relay. It is similar to the ordinary over current relay but it measures the ground current at the device X not at the power feeding line, and it compares the current variation value to the ground current in Device X to identify the correct faulted line. Though both type of the relays have pros and cons and can identify the faulted region correctly, the ground over current protective relaying scheme has more advantages than the other.