• 한국정밀공학회지
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• 제22권6호
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• pp.83-89
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• 2005

Most domestic fossil power plants have exceeded 100,000 hours of operation with the severe operating condition. Among the critical components of fossil power plant, high temperature steam pipe systems have had a many problems and damage from unstable displacement behavior because of frequent start up and shut down. In order to prevent the serious damage and failure of the critical pipe system in fossil power plants, 3-dimensional displacement measurement system was developed for the on-line monitoring. Displacement measurement system was developed with a use of a LVDT type sensor and two rotary encoder type sensors. This system was installed and operated on the real power plant successfully.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.345-346
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• 2010

The HVAC(Heating Ventilation and Air Conditioning) system is only controlled by turn on/turn off operations against to AC 380V input. Therefore, the efficiency of the system is reduced and noise occurs. Also, the blower is shut down at the AC power failure. In this paper, the inverter system with UPS function for the A/C(Air Conditioning) blower is proposed. Proposed inverter system which is powered from the AC and DC voltage can control speed, operation mode, and soft-start time using CAN communication. In case of the CAN communication failure, RS-232 communication could be used to control the hardware directly by the engineer that can solve existing problems. To verify the validity of proposed inverter system, simulations and experiments are carried out.

• 한국생산제조학회지
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• 제8권4호
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• pp.112-122
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• 1999

In realistic control systems the nonlinear saturation attributes of the control actuator due to physical limitations should be taken into account This nonlinear saturation of actuators may cause not only deterioration of the control performance but also a large overshoot during start-up and shut-down. As the overshoot increases the system may become oscillatory unstable. in this paper the supervisor implementation which guarantees good performance for saturation operation and prevents reset wind up is presented, Moreover the sufficient conditions of the stability for saturated system using supervisory control with a dynamic controller are provided in the continuous-time and in the discrete-time domain Numerical example is illustrated to depict the efficiency of supervisory control for a typical satuaurated production-distribution system controlled by a discrete-time dynamic controller and to validate basic results by simulation.

• KEPCO Journal on Electric Power and Energy
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• 제2권4호
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• pp.583-588
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• 2016

The high-temperature steam pipes of thermal power plants are subjected to severe conditions such as creep and fatigue due to the power plant frequently being started up and shut down. To prevent critical pipes from serious damage and possible failure, inspection methods such as computational analysis and online piping displacement monitoring have been developed. However, these methods are limited in that they cannot determine the life consumption rate of a critical pipe precisely. Therefore, we set out to develop a life assessment system, based on a three-dimensional piping displacement monitoring system, which is capable of evaluating the life consumption rate of a critical pipe. This system was installed at the "M" thermal power plant in Malaysia, and was shown to operate well in practice. The results of this study are expected to contribute to the increase safety of piping systems by minimizing stress and extending the actual life of critical piping.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.83-84
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• 2006

Lightning induced faults accounts for more than 66% at the transmission lines of KEPCO. The lightning causes damages to power system equipments including transmission line, the shut down of electricity and the electro-magnetic interference. Because of this reason, we need the real time lightning information for the optimal operation of power system. And, it is required to obtain and accumulate the lightning current parameters for the insulation design. A lightning detection system, LPATS, has been operated since 1995 in KEPCO. For the improved detection efficiency, we had in stalled the new lightning detection network named as KLDNet in 2005. Also, we had developed the new software for the lightning parameters analysis and real time information service on the WEB. In this paper, we would like to introduce about the new system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.497-501
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• 2000

One of the way to derive design parameters of the fuel feeding system in satellite is to analyze unsteady flow of liquid propellant (hydrazine) in the propulsion system. During steady thruster firing the flow rate is constant: if a thruster valve is abruptly shut down among a sets of thrusters, pressure spikes much higher than the initial tank pressure occur. This renders the fuel flow unsteady, and the fluid pressure and flow rate to oscillate. If the pressure spikes are high enough, there are possibilities that propellant explosively decomposes, thruster valves are damaged, and adiabatic detonation of the hydrazine propellant is potentially incurred. Reflected shockwaves could also affect the calibration and operation of the pressure transducers. These necessitate the analysis of unsteady flow in the propulsion system design, and the calculation results obtained through some governing parameter variation are presented in this work.

• 한국통신학회논문지
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• 제39C권10호
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• pp.930-936
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• 2014

본 논문에서 소개하는 스마트 멀티탭은 스마트 폰으로 서버 PC를 통해 제어되는 전자기기이다. 네트워크 망에서 동작하는 스마트 멀티탭은 기존 멀티탭에 무선통신 프로토콜인 Zigbee 통신 모듈을 내장시켜서 사용자가 홈서버를 통해 원격에서 가전기기의 전원을 제어할 수 있게 한다. 게이트웨이의 역할을 하는 홈 서버는 인터넷을 통해 스마트 기기와 연결되어 있다. 본 논문의 최종 결과물을 통해 사용자는 스마트 기기로 멀티탭의 ON/OFF 상태정보를 확인하고 즉시 제어를 하거나 사용자가 원하는 시간에 맞춰 제어를 할 수 있다. OFF시에는 SSR모듈로 전기가 지나가는 통로를 막기 때문에 스마트 멀티탭을 구동하는데 드는 미량의 전력 소모(2watt) 이외에 모든 대기전력이 차단된다. 이를 통해 전기에너지 절감 효과를 기대할 수 있다.

• 대한전자공학회논문지
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• 제10권4호
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• pp.60-73
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• 1973

두개의 검출기를 사용한 상호상관함수법으로 원자로의 잡음을 해석하여 TRIGA MARK-II 원자로의 동특성과 원자로의 안전을 위한 계수율 및 미임계시의 반응도를 측정하였다. 본 실험결과 원자로의 영출력과 전출력시의 임계상태에서 α값은 각각 46.67과 70.04로 얻어졌으며 안전봉낙하에 의한 임계미미상태에서는 79.47, 그리고 조정봉낙하에 의한 임계미만에서는 97.57로 얻어졌다. 이때 l*값은 β가 0.0075때에 107μsec와 160μsec로 나타났으며 Shut down margin의 미임계도는 안전봉낙하시에 -10.03×10-4이었고 조정봉낙하시에는 -29.43×10-4이었다. 본 실험에서는 CDC 3100/MSOS Digital 전자계산기, HITACH 505 Analog 전자계산기와 직접 제작한 Preamplifier, Bandpass filter, FM-Moulator, FM-Demodulator 등을 이용하여 계산 측정하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 추계학술대회 논문집
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• pp.128-132
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• 2004

This paper proposed a control strategy for flywheel energy/recovery system with induction machine. The system is based on a vector controlled induction machine driving a flywheel and address the problem of regulating the DC-Link system voltage against input power shut-down. And we proposed the method to damp the oscillation of DC-Link. Experimental results are presented which verify the performance of the strategy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.169-171
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• 2003

Because the overhead transmission lines are exposed to the outdoor weather, the faults of the transmission tines are due to natural conditions, and among these faults, the outage rate by lightning is about 50%. The lightning causes the damage of power system equipments, the shut down of electricity and the electro-magnetic interference. Therefore, the pertinent insulation design is important, not only to decrease the damage of the facility itself but also to increase the reliability of electric power system. For these reasons, we have to obtain and accumulate the lightning current parameters for the basic lightning research. This paper describes the development of real time analysis system about lightning information.