• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.526-530
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• 2008

전력계통의 경제급전은 전력거래시스템 및 에너지관리시스템(EMS)에서 사용되는 중요 기능 중의 하나이다. 경제급전의 계산은 대규모 행렬로 구성된 선형방정식에 기반하고 있다. 전력계통에 IT 기술을 이용한 여러 서비스가 개발 가능해짐에 따라 처리할 데이터량도 점차적으로 증가하고 있다. 본 논문에서는 이러한 경제급전을 병렬처리를 이용해 수행 속도를 향상시키는 방안을 제시하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.576-579
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• 2007

마이크로스트립으로 급전되는 슬롯 안테나를 소형화하기 위해 폴디드 슬롯과 T형 마이크로스트립 선로로 구성된 안테나 구조를 제안하였다. 전형적인 마이크로스트립으로 급전된 슬롯 안테나와 성능(안테나 크기, 슬롯 길이, 대역폭 등)을 비교하였으며, T형 마이크로스트립선로를 이용한 급전선로의 임피던스정합 방법에 대하여 설명하였다. 제안된 구조로 유전제기판상에 2.45GHz 대역 WLAN용 안테나를 설계 및 제작하였으며 특성 실험(반사손실, 부사패턴)을 통해 연구의 타당성을 확인하였다.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.127-131
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• 2001

본 논문에서는 공진 주파수가 2 GHz 이며 크기가 작고, 광대역 특성을 갖는 Taper 형태의 급전선로를 갖는 마이크로스트립 Bow-tie 슬롯 안테나를 제안하였다. 이 구조에서는 대역폭을 향상시키기 위하여 마이크로스트립 슬롯 안테나 방사 슬롯을 변형된 bow-tie 모양으로 설계하여 기존의 Bow-tie 슬롯 안테나와 다른 구조를 제안하였고 Electromagnetic coupling를 좋게 하기 위하여 급전선로에 Taper를 첨가하여 급전기와 안테나의 정합을 이루어 광대역 특성을 갖도록 하였다.

• 전기의세계
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• v.25 no.1
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• pp.21-29
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• 1976

직류 급전 계토으이 고장은 트롤리선과 레일 사이의 단락이며 이것은 또한 1선지락 고장이다. 이 고장 전류와 격변하는 부하 전류를 정확하게 판별하여 고장 전류만 차단하기 위하여는 선택 차단 방식이 필요할 뿐 아니라 직류 차단 전류는 교류의 경우에 비하여 일반적으로 차단이 어렵기 때문에 고장 전류를 신속히 차단할 수 있는 고속도 차단기가 필요하다. 그러므로 본고에서는 이러한 기초자료를 얻기 위해 직류 급전 계통의 고장 전류를 계산하고 검토하고져 한다. 이를 위하여 먼저 지하철의 전력 계통에 대한 구성 개요를 살펴보고, 직류 급전 계통의 정상 운전 특성 중에서 나타나는 일반적인 특성 검토와 고장 전류의 계산을 하여 본 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.672-678
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• 2020

The parallel-feeding operation of an AC traction power supply system has the advantages of extending the power supply section and increasing the power supply capacity by reducing the voltage drop and peak demand caused by a train operation load. On the other hand, the parallel-feeding operation is restricted because of the circulating power flow induced from the phase difference between substations. Moreover, the power supply capacity is limited because of the unbalanced substation load depending on the trainload distribution, which can be changed by the train operation along the railway track. This paper suggests a Thyristor-controlled Phase Angle Regulator (TCPAR) to reduce the circulating power flow and the unbalanced substation load, which depends on the phase difference and the trainload distribution and provides a feasibility study. A dedicated control model of TCPAR is also provided, which uses substation power supplies as the input to control the circulating power flow and an unbalanced substation load depending on the phase difference and the trainload distribution. Simulation studies using PSCAD/EMTDC shows that the proposed TCPAR control model can reduce the circulating power flow and the unbalanced substation load depending on the phase difference and the trainload distribution. The proposed TCPAR can extend the parallel-feeding operation of an AC traction power system and increase the power supply capacity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.496-502
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• 2007

In this paper, a slotted waveguide feeder for the electric field uniformity in multi-mode cavity is designed and fabricated. In case of the conventional feeder, a mode stirrer or a turntable is used for improving electric field uniformity in the multi-mode cavity. The proposed feeder has four slots, which have uniform radiation characteristic, on broad wall and shorted terminations at both ends. The electric field uniformity is simulated by CST's MWS(Microwave Studio) for the conventional and proposed feeders, respectively. The fabricated feeder shows the return loss of less than -20 dB at 2.45 GHz. To verify the validity of our proposal, the temperature distribution of the water samples in the multi- mode cavity is observed after a few minutes' heating. The proposed feeder is confirmed to have much better field uniformity in the multi-mode cavity than the conventional feeder.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.138-146
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• 2010

DC railway power supply system generally uses the running rails as negative-polarity return conductor for traction load current, and the induced rail potential and stay current cause serious problems to any electrified matter in the underground and also safety problems to human body. This paper presents a new algorithm for the analysis of the rail potential and the stray current in DC railway power system operated under independent/parallel power feeding mode. The effect of load current fluctuation during train operation is also calculated by using TPS(Train Performance Simulation) program to analysis the variation of the railway potential and stray current along railway track. Simulation program is developed based on the proposed algorithm and case studies are provided.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.567-569
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• 2012

An inducing current of power feeding line of high-speed railway system is varied by a relative position of telecommunication cable to the feeding line between plants. An analytical calculation formula of this inducing current is described in ITU-T Directives using multiconductor line method or two line method. In this paper, using the two line method, a variation characteristic of inducing current is simulated. The inducing current has a characteristic of hyperbolic function which is a symmetric shape of curve in the range between power feeding plants. This basic variation property can be considered when a power induction protection measure is planned.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.143-150
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• 2000

In this paper, an optimum size for the inset cut feed of microstrip antennas has been determined by using the finite-difference time domain method. At first, the return losses of microstrip antennas having various shapes and types of the inset cut feeds have been computed numerically for a given frequency and a substrate. Then an optimum size of the inset cut feed has been determined by iterative computation procedure for a given condition. It was found that the optimum width of the inset cut feed is about 0.42 times of the width of 50Ω feed line and the optimum length of the inset cut feed is about 0.36 times of the length of the antenna patch. These results are proved by the experimental data obtained from the measurements of many fabricated antennas. It was also found that the optimum size of the inset cut feed is independent on the frequency, the height and the dielectric constant of the antennal substrate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.35-41
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• 1997

A series-fed microstrip array antenna of beamwidth $10^{\circ}$, squint angle $80^{\circ}$ and SLL -15 dB below is designed. Series-fed arrays are formed by interconnecting all the elements by high-impedance transmission lines and feeding the power at the first element and it is a traveling-wave antenna which is terminated with a matched load. Radiation patterns and impedance matching of the antenna are analyzed by Ensemble 4.0, which is a popular software package for designing printed antennas and arrays. The squint angle of beam can be controlled by the spacing between the elements. The major advantages of series-fed array antennas are that feed arangement is compact and the losses associated with the feeding network are less than those of a corporate feed type. The antennas are fabricated on the RT/Duroid Laminates of 62 mil thickness. The experimental results are very close to the specifications to be designed.