• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.90-94
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• 1987

A structured user-friendly procedures which enable users to program in GRAFCET form directly from sequence specifications have been developed. Using these procedures, we can program the programmable logic controller (PLC) in sequential control and realize programming, debugging, and real-time monitoring. GRAFCET has many advantages like parallelism expression, so we can expect higher productivity and easier maintenance than boolean language or relay-ladder diagram specification when adapts them to PLC.

• KIEE International Transactions on Power Engineering
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• 제2A권4호
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• pp.153-159
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• 2002

Power transformer protective relay should block the tripping during magnetizing inrush and rapidly operate the tripping during internal faults. Recently, the frequency environment of power system has been made more complicated and the quantity of 2nd frequency component in inrush state has been decreased because of the improvement of core steel. And then, traditional approaches will likely be maloperate in the case of magnetizing inrush with low second harmonic component and internal faults with high second harmonic component. This paper proposes a new relaying algorithm to enhance the fault detection sensitivities of conventional techniques by using a fuzzy logic approach. The proposed fuzzy based relaying algorithm consists of flux-differential current derivative curve, harmonic restraint, and percentage differential characteristic curve. The proposed relaying was tested with relaying signals obtained from EMTP simulation package and showed a fast and accurate trip operation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1871-1873
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• 1997

The conventional current transformers are often take faults and out of order that for detect to over current of electric power lines because electromagnetic interference. But, it is possible to implement protection relay of high reliability using optical magnetic field sensor which are immunity and small size. The optical magnetic field sensor is possible to rapidly detect to over current and recover when electric power line have fault. And it is not necessary to make with capacitance of electric power lines as optical magnetic field sensor is have linearity from 0 to about 20kA. In this study, we designed and constructed compensative feedback circuit in order to minimize of optical power intensity variation with environ- mental variations(temperature, drive current) of light source. And this system have highest optical advantages and reliability.

• 한국IT서비스학회:학술대회논문집
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• 한국IT서비스학회 2003년도 춘계학술대회
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• pp.607-614
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• 2003

멀티미디어 스트림 전송에 있어서 대량접속자를 수용하기 위해서는 서버에 많은 리소스와 대역폭이 집중되어야만 하는데, 소수의 클라이언트 접속만을 수용할 수 있고 적은 리소스와 대역폭을 갖는 서버의 경우, 이미 접속한 클라이언트가 서버 기능을 해서 중계할 수 있다면, 추가적인 접속은 중계가 가능한 다른 클라이언트로 접속하게 할 수 있다. 이렇게 피라미드 형태로 접속이 분산하기 위해서 P2P 접속을 이용한다면, 적은 리소스와 대역폭을 가지고도 대량접속자를 수용할 수 있는 대안이 될 수 있다. 실제로 이러한 구조로 어떤 어플리케이션이 가능한지, 또 얼만큼의 성능개선효과가 있는지 고찰해보고자 한다.

• 한국ITS학회 논문지
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• 제10권4호
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• pp.116-124
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• 2011

Binary CDMA네트워크에서는 네트워크 각 엔터티들의 네트워크 자원을 마스터 스테이션이 관리하므로 마스터 스테이션의 관리 범위한계를 경계로 하는 Pico-net내에서만 통신이 이루어질 수 있다. 본 연구에서는 이러한 제한을 극복하여 보다 광역적인 네트워크에 Binary CDMA를 응용할 수 있는 방안으로서 네트워크를 Cell단위로 분할하여 다중의 Pico-net들로 구분하고 각 Pico-Cell에 고유의 네트워크 주소체계를 만들어 Pico-Cell간에 데이터를 중계하는 기능을 가지는 Binary CDMA 라우터 장치의 고안방법에 대하여 제시하였다.

• 조명전기설비학회논문지
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• 제24권9호
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• pp.150-158
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• 2010

We had experienced the several system failures which were concerned about zero sequence voltages at the tertiary side of 345[kV] transformers. In this paper, we had considered the zero sequence voltage and its reduction methods at the 345[kV] auto-transformer tertiary. For analysis, we used EMTP(Electro-Magnetic Transients Program). The calculation results by EMTP were compared with the measured data of the field tests. From the calculation and the field tests, we had verified that it is due to pre-saturation characteristics of the potential transformer. So, we had improved its saturation characteristics and applied it at real site. After improvements, we could reduce the zero sequence voltage below the setting level of the relay.

• 전기학회논문지P
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• 제57권1호
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• pp.46-55
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• 2008

In this paper, we designed the bay control unit that is based on the microprocessors and integrates with the new technology of electrical, electronic, and mechanical fields. Nowadays the customers have required much more integrated multi-protection relay, monitoring, control devices and power management for better and easier maintenance, performance, electrical system analysis and communication according to new trend of switchboard This bay controller supplies those requirements of customers with easy handling and operation. This bay controller provides a graphic display with rear-lit liquid crystal LCD and push buttons as kinds of HMI(Human Machine Interface). This bay controller provides the parameter setting program, control setting program, various editors and fault recording and analysis program on Windows/95/98/NT/2000/XP for HMI. In addition, this bay controller can be set manually and this manual setting function helps user to interface easily.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1203-1205
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• 1998

Fault Detection of power system must be rapid and precise over input signal without relation to any disturbance. But, it is difficult to detect current unbalance, over voltage, and underfrequency for digital relay comparison of fault perfectly. In this paper, we measure each phase current and infer type of fault using fuzzy pattern classification.

• 한국컴퓨터정보학회지
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• 제15권1호
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• pp.219-223
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• 2007

이 논문에서는 기존 개발된 일체형의 통합 터미널 보드의 유선방식으로 자동제어시스템에서의 중요 신호에 대한 전체적 통합관리시스템 구축을 위한 DCS터미널 원격 감시 보드를 설계 제작하고 제작된 보드의 동작을 테스트하기 위해 원격감시 프로그램을 구현하여 기능을 평가한다. 구현된 원격감시보드는 전원관리실의 각 릴레이들의 동작상태 및 릴레이와 퓨즈의 이상 유무를 실시간으로 확인이 가능하며 릴레이의 수명을 고려하여 릴레이의 고장을 사전에 예방함으로써 산업분야의 경제적인 효과가 기대된다.

• 전기의세계
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• 제13권2호
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• pp.5-10
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• 1964

Some nonlinearities in feedback control systems, such as relay servo, Coulomb friction, saturating amplifier of backlash in gears cause some undesirable effects. These may be static errors, limit cycles or jump phenomena. So, linearizing method of these nonlinearities using dither signals was first suggested by Loeb. He pointed out that the addition of high frequency signal to either the input or the output of a nonlinear system would make the nonlinear performance approximate the performance of linear systems. He used high-frequency sinusoidal wave as dither signal. But, in this thesis, general method of analysis is suggested for nonlinear control systmes using various dither signals, such as noise signal of Gaussian amplitude distribution, sinusoidal dither signal and sawtooth dither signal. Also, the advantage and disadvantage of these dither signals are compared. Throughout the analysis statistical method is adopted and lastly analog computer is used for the experiment of various nonlinear systems using dither signals.