• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.23-33
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• 2012

The current paper deals with a new live-line insulator inspection tool system that will be used by the Korea Electric Power Corporation for its 154 kV power transmission lines in 2011. Unlike the existing contact type tools, the developed inspection tool automates parts of the insulator inspection process using a sensor and an actuator. The tool sustains its weight independently, not by a lineman. In addition, the inspection tool measures the insulation resistance of an insulator together with its distribution voltage, thus providing more information for analysis and diagnosis. Such characteristics improve the system's operation efficiency, measurement reliability, and usability. We confirmed its effectiveness through live-line field tests with actual power transmission lines.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.205-207
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• 2003

The line impedance is important data that is applied in all analysis fields of electric power system like power flow, fault current, stability and relay calculation etc. Usually, impedance can be accurately calculated in case of overhead line. However, in case of power cables or combined transmission lines, impedance can not be accurately calculated because cable systems have the sheath, grounding wires, and earth resistance. Therefore, if there is a fault in cable system, these terms will severely be caused much error to calculation of impedance. Therefore, the line impedance were measured for this study in an actual power system of underground cables, and were analyzed by a generalized circuit analysis program EMTP for comparison with the measured value. These analysis result is considered to become foundation of impedance calculation for underground cable.

• 산업기술연구
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• 제18권
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• pp.431-437
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• 1998

In this paper, we presented a modeling of the power line channel and a new digital communication system over the channel. Firstly, we proposed a new tranceiver structure with DS-CDMA spread spectrum technique and convolutional coder and block interleaver against severe noisy power line environment. Also, QPSK modulation technique was used to get bandwidth efficiency. And then we performed a simulative evaluation of the system using MATLAB communication/simulink toolbox. According to the simulation results, the proposed system gives $10^{-6}$ BER at 20dB SNR.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.29-34
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• 2007

The input and output impedances in a low voltage distribution system is one of the most important matters for power line communication because from the viewpoint of communication, the attenuation characteristic of the high frequency signals is greatly caused by impedance mismatch during sending and receiving. The frequency range is from 1MHz to 30MHz. Therefore, this paper investigates the input and output impedances in order to understand the characteristic of high frequency signals in the low voltage distribution system between a pole transformer and an end user. For power line communication, the model of Korea's low voltage distribution system is proposed in a residential area and then the low voltage distribution system is set up in a laboratory. In the low voltage distribution system, S parameters are measured by using a network analyzer. Finally, input and output impedances are calculated using S parameters.

• 조명전기설비학회논문지
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• 제24권10호
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• pp.157-162
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• 2010

Power line communication, using 25[kV] high voltage of railway catenary, is to provide information which is real-time safety information for train operations and train workers in driving. Lots of noise were occupied in the contact wire by electrical and communication equipments. A signal attenuation was caused characteristics of the contact wire and messenger wire. For relaying communications to transmit information using the contact wire, catenary the noise and signal attenuation were investigated. And the final goal of the study was realized to transmit video information by power line communication on electric railway.

• 전기학회논문지P
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• 제53권2호
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• pp.58-64
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• 2004

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating voltage unbalance. Voltage unbalance is a condition in a polyphase system in which the rms values of the line-to-line voltages or the phase angles between consecutive line-to-line voltages, are not all equal. Slight voltage unbalance generates a disproportionately high current unbalance at the motor stator winding. This paper presents a scheme on operation states of a three-phase induction motor under unbalanced voltages. The three-phase voltages applied to the stator winding of the studied induction motor are controlled by respectively adjusting the magnitude and phase angle of each phase. The voltage unbalanced factor(VUF) of the three-phase source voltages can then be varied to examine the different values of VUF on machine's operation characteristics.

• 한국정보전자통신기술학회논문지
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• 제1권2호
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• pp.7-11
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• 2008

로컬 레벨의 표준화 및 시스템간의 상호운용성을 높이기 위하여 공기조화설비 제어 계통도를 지하층(8포인트)과 기준층(15포인트)으로 구분하여 설계하고 전력선통신으로 제어 네트워크를 구축하였다. 공기조화 시스템의 각 디바이스는 개방형 프로토콜인 뉴런 C로 프로그램 하였다. 연구 결과 $L_{ON}W_{ORKS}$ 프로토콜로 각 디바이스들의 자율분산제어가 가능하게 되었고 통신선의 길이와 회선수를 감소시킬 수 있었다.

• 정보통신설비학회논문지
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• 제3권2호
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• pp.26-32
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• 2004

This paper represents analysis on domestic technical regulation of high speed power line communications(PLC). Also it gives comparison of regulations for several countries which include U.S., Europe, and Japan. Power line communications radiates harmful interference in below 30MHz. This may intervene other radio equipments. The technical regulation must protect interference and provide clean radio environment. Finally this paper gives the proposal which is drafted by field tests for introducing high speed PLC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.186-188
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• 2004

This paper describes the feasibility study of HVDC system application to KEPCO power system for increasing power transfer capability or the flexibility of power delivery from one area to the other using the existing transmission line. This paper assumes the 345kV transmission line connecting between Shinokchun and Sedaegu to be converted to the DC line by replacing the AC insulator with that of DC. Then, the HVDC bipole system of 1000MVA with $\pm300kV$ is designed and the contingency studies are carried out.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.73-75
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• 2004

This paper presents the ability and the application of software packages for distribution planning which are DISPLAN(Distribution Planning System) and DLPLAN(Distribution Line Planning System) developed in KEPCO. After calculating size and position of maximum load by administration section for distribution, it forecasts the demand of distribution load considering growth location, increment, new load plan, etc of load by annual. Also it calculates distribution loss, voltage drop using modeled distribution line by you, and support for establishment and enlargement plan of substation and distribution line, decision of most optimal path. And it presents the abstract of used algorithm to develop this system.