• Journal of the Korean Society for Railway
• /
• v.15 no.2
• /
• pp.122-128
• /
• 2012

Considering structure of depot, it is impossible to install the track circuit systems due to iron-beam. Because rails and earth are connected by the iron-beam, there is much leakage current. So, it is hard to apply the track circuit systems. Thus, when trains go to the depot, sign which indicates existence of trains is used manually. In case of wrong sign, accidents occur such as train crash, derailment etc. Currently, location of trains has been found by using optical sensor in the depot to prevent the accidents. However, it costs a great deal to install and maintain the optical sensor. Therefore, this method is hardly used in train operation institutes. In this paper, virtual track circuit systems are introduced by using software program in the depot. Also, algorithm of the virtual track circuit systems is proposed. In case that signal is handled to the depot which is occupied by the train, safety is ensured by indicating sign which means existence of trains and stop signal. Also, proper fault tolerance techniques are proposed to the software by analyzing reliability and availability.

• Aerospace Engineering and Technology
• /
• v.3 no.2
• /
• pp.170-176
• /
• 2004

In this study, the relay driver circuit which controls the spacecraft configuration change are implemented and validated. First of all, the specification of the relay driver circuit is defined, and then its circuit meeting the specification defined is designed. In order to verify the design of the relay driver circuit, its circuit was simulated, and then it's confirmed that the relay pulse current and voltage level defined in the specification are obtained, and the results obtained through the functional test of the relay driver circuit are compared and well matched with the simulation results. Also the worst case analysis for confirming the stable operation of the relay driver circuit under the tolerance of each component is performed.

• Proceedings of the KIEE Conference
• /
• 2002.04a
• /
• pp.204-206
• /
• 2002

계통연계 풍력발전시스템의 특성을 고찰하기 위해서는 블레이드, wind turbine, 정류기, 인버터 등의 풍력발전시스템의 각 구성요소의 모델링과 적절한 제어 알고리즘에 대한 모의가 요구된다. 본 연구에서는 동기발전기를 풍력발전기로 사용하고 있는 계통연계형 풍력발전시스템의 출력 및 동특성을 모의하기 위한 전류제어형 전압원인버터의 PSCAD/EMTDC 모듈을 제시한다. 풍속의 가변특성에 의해 동기발전기에 들어오는 입력은 변하게 되고, 동기발전기가 동기주파수를 유지할 수 있도록 인버터에서는 이러한 입력과 동일한 출력을 낼 수 있어야 하며, 동시에 계통에서 허용하는 일정 전압과 계통주파수와 동일한 주파수를 갖는 출력을 공급해야 한다. 본 논문에서는 이를 위해 동기발전기의 주파수를 제어하는 전류제어형 전압원인버터 모듈을 소개한다. 모의를 통해 결과를 검증한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.4
• /
• pp.98-106
• /
• 2006

This paper is proposed an efficiency optimization control algorithm for a synchronous reluctance motor which minimizes the cower and iron losses. The design of the speed controller based on adaptive fuzzy-neural networks(AFNN) controller that is implemented using fuzzy control and neural networks. There exists a variety of combinations of d and f-axis current which provide a specific motor torque. The objective of the efficiency optimization controller is to seek a combination of d and q-axis current components, which provides minimum losses at a certain operating point in steady state. It is shown that the current components which directly govern the torque production have been very well regulated by the efficiency optimization control scheme. The proposed algorithm allows the electromagnetic losses in variable speed and torque drives to be reduced while keeping good torque control dynamics. The control performance of the hybrid artificial intelligent(HAI) controller is evaluated by analysis for various operating conditions. Analysis results are presented to show the validity of the proposed algorithm

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.2
• /
• pp.85-93
• /
• 2008

In 22.9[kV]-y distribution systems, underground cables are provided with 3-wire loop multiple-point ground in which each coaxial-neutral line of the distribution cable lines(A, B, C phases) is 3-wire common grounded at every connecting section. In the underground cable distribution systems, circulating current flows in the coaxial-neutral lines and its magnitude amounts to about $40{\sim}50[%]$ load currents, even though loads are balanced. This paper presents a new ground method to overcome such a problem and a comprehensive analysis in tows of current capacity of power cables, induced voltage of cable sheath, and electromagnetic interference voltage from power cable lines.

• Journal of the Korean Society for Railway
• /
• v.12 no.5
• /
• pp.687-693
• /
• 2009

An algorithm and a computer software are developed for the analysis of rail potential rise. The algorithm is intended to be integrated with the traction power system simulation program. In the algorithm, rail potentials are obtained by two step process. First the injection currents to the negative rail are obtained from load-flow study. In the next step, a network consisting of negative rail and the injection currents are constructed. Leakage resistance to ground are added to the network. And the network is analyzed for rail potentials. A software is developed to verify the validity of the algorithm. The result of the software is compared with the Simulink/SymPower circuit analysis result. The differences between the two results are with the acceptable range. The advantage of this algorithm is that it can be integrated with the existing traction power supply simulation program easily, which usually ignores negative rail's leakage resistance.

• Journal of the Korean Magnetics Society
• /
• v.25 no.3
• /
• pp.87-91
• /
• 2015

This paper reports the design of solenoid in a coilgun for high velocity of projectile in a coilgun system, according to diameter of coil. Coilgun using a magnetic force means a mechanism that can control the magnetic material. When momentarily supply a large current to the solenoid instantaneous magnetic field is created around the coil, the projectile is fired by receiving a magnetic force towards the center of the coil, based on the right-hand rule of Fleming. The velocity of projectile is proportional to the magnetic force generated by the electromagnetic coil. The current affects the life of the coil and the current limit exists. Therefore, the coilgun design, which does not exceed the current limit and the magnetic forces are at the maximum, is required. In this paper, whether it is possible fire looking for the optimal number of turns according to the diameter of the coil from AWG #6 to AWG #18 for the design of the solenoid coil, and comparative analysis firing rate associated with it.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1189-1190
• /
• 2011

본 논문은 전기자동차(EV, Electric Vehicle)에 충전용 대용량 직류(DC) 전력을 공급할 수 있는 급속충전기를 개발하고 그 성능을 정의하며 충전성능시험장치를 개발하여 급속충전기의 성능시험을 한 결과에 관한 것이다. 급속충전기는 EV의 충전에 필요한 시간을 단축하고자 배터리가 허용하는 한계까지 전압, 특히 전류를 높여 급속히 충전을 한다. EV와 충전기 사이에는 이러한 전력공급 외에도 커넥터 연결확인 및 차량존재 유무 등의 안전을 체크하는 아날로그 시그널과 EV의 배터리관리장치(BMS)에서 충전기에 필요전력을 통보하는 디지털 통신이 필요하여 충전성능을 시험하기 위해서는 전력, 아날로그 시그널, 디지털 통신을 차량 대신 동시에 주고받으며 충전기를 시험하는 충전성능 시험장치가 필요하다. 본 논문에서는 어떻게 시험장치를 구성하여 이러한 실험을 수행하였는지, 그리고 충전기성능 분석결과를 설명하고자 한다.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.2160-2161
• /
• 2011

IEC 61936의 저압기기 허용 상용주파 과전압에 대하여 선로의 지락고장시 고장전류의 분류 효과 및 등가회로를 이용하여 수학적 계산식을 도출하고 EMTP를 이용하여 모의를 수행하였다. 또한 시험선로를 이용하여 실증시험을 수행하여 실제 고장현상을 검토하였다. 현재 배전계통의 접지수준은 기준을 충분히 만족하고 있으므로 다양한 사례 연구를 통하여 접지기준의 개정을 검토할 필요가 있는 것으로 판단된다.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.583-585
• /
• 2005

선로의 DLR을 추정하는 방식 중에서 간접도체 방식은 시험도체가 선로의 도체와 유사한 환경에 직접 노출되어 있어서 일사량, 풍속, 풍향 통 측정감도가 낮은 요소들을 직접 측정하여 사용하지 않아도 이들의 종합적인 효과를 반영할 수 있는 장점이 있다. 본 논문에서는 간접도체 방식에 의한 DLR 추정 알고리즘을 보이고 가열도체와 비가열도체를 사용한 실험을 통하여 추정 풍속 및 DLR 산정결과가 실측 풍속 및 기상요소로 추정한 값들과 거의 일치함을 보임으로써 DLR 산정 방식으로서 간접도체 이용의 타당성을 제시하였다.