• 한국철도학회논문집
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• 제9권4호
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• pp.394-400
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• 2006

Since Seoulmetro built the first line of electric railway at seoul 1974, the passengers of railway have been increased rapidly, and electric railway requires more electric power for the greater capacity of transport. It is important that we prevent the accidents related with the subway, because all systems of subway are constructed in artificial underground structure. Since the previous versions of the earth system were built to meet the old standards of the electric facility for the lightning, some accidents related with the DC earth fault are causing secondary damages to the electric equipments. So, the old grounding system must be improved, and new standards of grounding system are required. We compare the grounding systems of the domestic railway corporations and the accidents that are related with the grounding systems. And we give ideas to improve the grounding systems and present standards which are suitable to electric railway.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.36-40
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• 2010

In recent society, the electricity is so essential for the human lives. Lots of modern people take many cultural benefits owing to the development of the power systems, the cell phone, the electrical appliances, and etc. However, the problems related to the electromagnetic field generate as the side effects. Examples are the fault in the electric machinery due to the electromagnetic coupling, the fault in the communication devices due to the electromagnetic field around the power line equipments, and the effect upon the human beings due to the electromagnetic field, and etc. In this paper, we induce the vector equation about the magnetic field based on Biot-Savart law. We calculate the magnetic field at the surface of the high speed train with this induced equation and the current in the high speed railroad catenary wire. Finally, we calculate the magnetic field in the high speed train considering the material property like the permeability, the conductivity, and so on.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1456-1459
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• 2007

Protective equipments have a very important protection role in power accident on catenary line. These equipments are installed on electrical pole. The poles have complicated with many bands(moveable bracket, branch wire anchor, shield wire, etc). So we have improved bands and installed bands on pole to test technical condition. The Result has showed effectiveness due to fixed position change of fault protective wire and to improve band shape. For example, reduction of band made cost, simplification of installing, correct position of protective wire and shield wire.

• 전자공학회논문지A
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• 제32A권12호
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• pp.198-208
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• 1995

BiCMOS circuit consist of CMOS part which constructs logic function, and bipolar part which drives output load. Test to detect stuck-open faults in BiCMOS circuit is important, since these faults do sequential behavior and are represented as transition faults. In this paper, proposes a method for efficiently detecting transistor stuck-open faults in BiCMOS circuit by transforming them into slow-to=rise transition and slow-to-fall transition. In proposed method, BiCMOS circuit is transformed into equivalent gate-level circuit by dividing it into pull-up part which make output 1, and pull-down part which make output 0. Stuck-open faults in transistor are modelled as transition fault in input line of gate level circuit which is transformed from given circuit. Faults are detceted by using pull-up part gate level circuit when expected value is '01', or using pull-down part gate level circuit when expected value is '10'. By this method, transistor stuck-open faults in BiCMOS circuit are easily detected using conventional gate level test generation algorithm for transition fault.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기설비전문위원
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• pp.83-88
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• 2004

As the electric system is getting larger to meet the increasing demand for electric power, the rating of power apparatus is becoming inevitably higher in its working voltage and larger in its capacity. According to KEPCO reports, power transformers in the KEPCO system have undergone troubles such as winding short insulation breakdowns every year since 1981. the cause of this troubles were high one line grounding fault currents in KEPCO systems that had direct grounding systems. KEPCO has installed the NGR(neutral grounding reactor) to lower this fault current and reduced winding short insulation breakdowns in power transformers. But when a circuit breaker opened a no load bus, some trips of circuit breakers for protecting transformer have occurred by mal-operation of 59GT(overvoltage ground relay) that detect disconnection of NGR. Therefore, in this paper, we analyzed the cause and examined the effect of time delav circuit to prevent wrong operation of 59GT.

• 전기학회논문지
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• 제59권10호
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• pp.1748-1753
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• 2010

This paper suggests an improved technique to establish the modeling regarding steady and transient state on three phase-in one cryostat type HTS(High Temperature Superconducting) cable. The proposed modeling is established using EMTP/ATPDraw and TACS and MODELS provided by that. It has higher accuracy than the conventional method, as the actual HTS cable is modelled. Steady and transient state analysis performed by EMTP/ATPDraw calculate the current of conductor, shield and former, respectively. In case of the transient state modeled quench state occurred by a single line-to-ground fault, current of conductor shield and former are also calculated, respectively. Especially, various fault resistances and angles are considered to improve the reliability during transient state analysis. Analysis results reveal that the proposed technique improves the accuracy of modeling.

• 전기학회논문지
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• 제58권12호
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• pp.2342-2348
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• 2009

Even though underground transmission cable is an essential transmission method to supply stable power for downtown and population center, the interaction of electromagnetic force by fault current is very large comparing to overhead transmission line due to restricted installation space such as tunnel, and close consideration is required for it. This paper presents countermeasures to reduce and release the effect of electromagnetic force with rope binding and installation of spacer and describes its efficacy through three phase short-circuit test, which will be utilized as basic materials for improvement and development of cleat, hanger, etc. to reduce and release effect of electromagnetic force in the future.

• 전기학회논문지
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• 제57권9호
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• pp.1589-1593
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• 2008

The condition of a high voltage motor was monitored with the motor performance monitor (MPM) at the motor control center. The MPM detected defects in the rotor bar and end ring and input power according to motor and load conditions. The assessment of the condition of a coal pulverizer motor indicated it was clearly in good condition in terms of the rotor bars, over voltage, and motor performance. However, the side bands at frequency, 56.48 Hz indicated existence of rotor end-ring fault. The large torque ripple indicated abnormal operating conditions. After visual inspection, it has been observed that an impeller blade of the circulating water pump was broken off causing the irregular torque pattern.

• 한국지능시스템학회논문지
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• 제11권2호
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• pp.101-108
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• 2001

본 논문에서는 배전선로에서 발생하는 여러 고장유형을 판별하기 위해서 적응형 퍼지추론 시스템을 적용하는 새로운 기법을 제시하였다. 배전선로의 고장과 고장유사현상 데이터를 추출하기 위해서 EMTP를 이용하여 RL부하, 아크로부하, 컨버터부하가 있는 배전계통을 구성하고 여러 형태의 고장과 고장유사현상에 대해 시뮬레이션을 하였다. 이를 통해 얻은 전류 파형으로부터 기본파성분, 영상분전류, 짝수 고조파성분의 합, 홍수 고조파성분의 합, 그리고 비정규 고조파성분의 합의 5개의 입력변수를 추출하고 학습을 통해서 각 입력변수의 소속함수의 소속도를 자동으로 결정하였다. 이 적응형 퍼지추론 시스템을 이용한 기법을 평가하기 위해서 학습시와 다른 고장상황을 모의하여 얻은 데이터와 실증시험 데이터를 이용하였다. 결과적으로 제안한 기법은 배전선로에서 발생하는 고장유형을 빠르고 정확하게 판별할 수 있었다.

• Progress in Superconductivity
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• 제12권1호
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• pp.23-26
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• 2010

A double line commutation (DLC) type SFCL with first peak limiting function has been proposed for ideal fault current limiting operation. Very fast switching (commutation) without any arc or high voltage problems for any kind of switching device is needed for the first peak current limiting. We've tried to find suitable conditions for a successful switching of a Vacuum Interrupter (VI) with HTS elements as a Peak Current limiting Resistance (PCR).