• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1402-1404
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• 2000

The electrified railway has various power supply schemes. Although the identical trains are operated in same condition and the impedance of track are equal, the genealogy impedance of track is changed according to composition method of feeding scheme. So, the harmonic current flowing into the railway substation are greatly unlike. For simulation of harmonic magnification flowing into the railway substation according to feeding scheme, we propose 6-port network analysis method based on 4-port network, find 6-port equivalent model of each circuit component, and compare and investigate harmonic magnification in the case of parallel post and normal feeding scheme.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.131-141
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• 2007

This paper proposes analysis on new equipment for power quality in electric railway. The proposed equipment consists of series inverter and parallel inverter. Each inverter is connected by capacitor as dc link. This structure can be compensated for active and reactive power in catenary through transformer. We verified the proposed equipment using the PSCAD/EMTDC and the calculation results from the proposed approach are widely described in the paper.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.772-777
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• 2009

The development of fuel cell hybrid power system, as a next generation power system to promote clean energy which will mitigate the continued global warming, has demonstratd a significant progress in passenger vehicle applications. Also, in case of railway vehicles in non-electrified railway lines, the adoption of fuel cell hybrid power system is being studied among well-known manufacturers. This paper introduces both the configuration and the control strategy of fuel cell hybrid power system to apply to a light electronic railway vehicle having a repeated driving pattern of acceleration, coasting and deceleration. The simulation results demonstrate the viability of the proposed power system design and its control strategy.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1236-1238
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• 2001

The electrified railway has various power supply schemes. Although the identical trains are operated in same condition and the impedance of track are equal, the genealogy impedance of track is changed according to composition method of feeding scheme. So, the collection voltage of train and supplying power from railway substation are greatly unlike. For simulation of collection voltage and power supply according to feeding scheme, using 6-port network analysis proposed previously simulate collection voltage and supply power according to feeding scheme(Parallel Post feeding system, normal feeding system and tie feeding system) and compare and investigate each characteristics.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.139.1-146
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• 2001

Contact lines are necessary to supply electric locomotives with electric power. As most railways are gradually electrified with modernized electric cars, the demand for catenary wires and their facilities are also increased. Catenary wires made by metallic materials are generally used in the open air. They are exposed to the marine area with air-borne salt or severely polluted industrial area with much corrosive emission gases depending on the railway locations. In urban area, acid rain may cause a degradation of catenary wire system. Corrosion of catenary wires can make their actual lifetime shorter than that originally designed. Thus, the messenger wires, a kind of catenary wire system, were investigated with respect to corrosion, which include new and the used one collected at the field. They are also vibrated with some amplitude everytime the train passes through the railway. The frequent cyclic load on the wire any result in a fatigue damage, Surface damage by corrosion can make fatigue crack initiate with ease. In the present study, the fatigue life of the used wire was measured 40 to 50% shorter than that of new one in average.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1407-1412
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• 2004

Impedance calculations of electric railway traction systems is essential to define characteristics and to design it. The self impedance is defined voltage drop rate per unit length, the mutual impedance is represented as a voltage induced to transmission line from transmission line. The self and the mutual impedance are influenced by ground return currents. The earth is considered as a semi-infinitely extended non-ideal conductor. The current of transmission line produces earth current induced magnetically and it flow through a path having minimum impedance. Carson proposed the impedance calculation formula using wave equations and magnetic field equations. Though the formula have an improper equation, that is still used as a standard impedance calculation method. This paper introduced an impedance calculation method that the complex depth of earth return method assumes that the current in conductor returns through an imagined earth depth path located directly under original conductor at a depth of. In this paper, we showed that this proposed method has a closed form and is easier than Carson's.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.294-301
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• 2008

At the neutral sections, There are neutral sections inserted in overhead contact line between the substations to divide different phase current sections of AC electrified lines. Except convention line, a large stress occurs in the contact wire near the fittings under passing pantographs. So, in order to raise the train speed over 150km/h, a new type section has been adopted.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1335-1342
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• 2013

Subway is electrified railway system nowadays, in which liquid dielectric transformers have been widely used, though mold type transformers are replacing it. The transformers supplies large electric power and have innate hazards causing accidents under operation. A number of researcher have carried out on failures of it and have oriented to identify transformer's failure causes and how to maintain it healthy state. The transformer failures can cause serious accidents which can provoke economic loss and leads persons to kill. In this paper, we carried out a safety activity to reveal hazards and to estimate risk of subway liquid dielectric transformers using FMEA, HAZOP and What-if methods. In case of installing safety devices in oil immersed transformer, we tried to evaluate an effect on a subsystem's failure rate. We proposed how to design subsystem failure rate and safety device failure rates.

• Journal of the Korean Society for Railway
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• v.5 no.1
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• pp.32-39
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• 2002

As most railways are gradually electrified with modernized electric cars, the demand for catenary wires and their facilities are also increased. Catenary Wires are exposed to the marine area with air-borne salt or severely polluted industrial area with much corrosive emission gases depending on the locations. Corrosion of catenaty wires can make their actual lifetime shorter than that originally designed. Thus, the messenger and ACSR wires, kinds of catenary wire system, were investigated with respect to corrosion, which include new and used ones collected at the field. Tensile strengths and elongations appeared to decrease when the wires were exposed to corrosive environments. The amount of decrease was more prominent as environmental conditions became more corrosive. They are also vibrated with some amplitude everytime pentographs touch contact line. The frequent cyclic load on the wire may result in a fatigue damage. Surface damage by corrosion can make fatigue crack initiate with ease. In the present study, the fatigue life of the used wire was measured 50 to 60% compared with that of new one in average.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.767-775
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• 2005

Power Supply System for electric railways is diversified with technical development and is required high technologies. especially, recently there is required many research and development for earthing to ensure safety of people and protection of installations. Generally, leakage resistance is high between rail and ground at tunnel section of subway. because of short circuit of feeding line, earthing interference by transient overvoltage between signals and communication system, and insulation failure, it can damage to human and equipments To minimize these obstacles, earthing equipment is installed at underground section of railway, but it brings about problems in accordance with operate each earthing system to be not enough required protection provisions for electrified railways. This paper proposes effective earthing method to be concerned about installation cost and maintenance. The validity of the proposed earth method is verified by simulation results at underground section of railways.