• 대한전기학회논문지
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• 제45권4호
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• pp.474-483
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• 1996

In this paper, as a part of the method improving stability, the load-flow calculation in D.C. power system and the models for stability analysis are studied with A.C-D.C. interconnected power systems transmission performed. Moreover, the theory is established in relation to each control method of D.C. power systems. Then the stability of A.C-D.C.interconnected power systems is compared and considered by the way of dividing the operating control method of the rectifier inverter converter into ACR-AVR, APR-A.gamma.R, A.alpha.R-ACR. The dynamics characteristic of terminal voltage, frequency, active-reactive power and rotor angle of the generator with disturbances and load fluctuations is considered. In addition, the characteristic of direct voltage, direct current, power and control systems. From this the comparative analysis of the direct current control method, the possibility of the stability analysis of A.C.-D.C. interconnected power system is considered. (author). refs., figs., tabs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.277-279
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• 2005

Recently, due to the increase of power conversion devices and nonlinear loads with the development of information, communication and control technologies, the instantaneous minute interruption factors such as voltage & current harmonics, surge occurring frequency, instantaneous voltage variation, voltage unbalance, flicker etc. have greatly threatened the power quality, and the deterioration of electric power facilities and the functional error of controllers are increasing. As such an instantaneous minute interruption appears to be small and local, accurate evaluation with measurement is difficult and total analysis system is required through a wide range of power quality effect analysis such as the simultaneous measurement on various power supply phenomena and the analysis on the interrelation with system loads. Most of conventional power quality diagnosis equipments have beer developed and applied, which were able to measure the stability rate of frequency, the stability rate of voltage, the electricity-failure duration etc, However, they were insufficient to analyze the system present situation, understand the cause of the failure occurred by the problem of power quality and analyze out the phenomena. Accordingly, this study will address the development of the system for a wide range of power quality diagnosis over the present level, the system for supporting the determination such as the analysis on risk factors, failure mode and impact, the system for harmonic evaluation based on international standards(IEC 61000 Series) and the total power quality diagnosis network & system with the extension and openness as a local and national-scale broadband power quality diagnosis system.

• 전기학회논문지
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• 제58권12호
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• pp.2322-2327
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• 2009

Uncertainty of power system operation increases due to complexity and facilities diversification in the power system. Therefore the importance of SCADA(Supervisory Control and Data Acquisition) system which obtain and manage the actual data in real-time is very important. Accordingly in the studies of power system analysis, the efforts to include real-time power system analysis in simulation and applications are made in many ways. The real-time communication characteristics of SCADA system is considered so as to develop the power system analysis program that matches actual system conditions. The observation and management of SCADA system is realized by Intouch which is mainly used for factory automation and PSS/E(Power System Simulator for Engineers) provides real time system data. SQL DB and Python language is used for real-time communication between the softwares. It is very comfortable to use the various functions in Intouch WindowMaker.

• 전기의세계
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• 제27권5호
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• pp.5-12
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• 1978

1.Power utilities and CRIEPI are very active in almost all aspects of power systems research. 2.About 50% of research activity of CRIEPI is made under the joint work with power utilities. 3.Research motivation of manufactures are mainly stimulated by the need of power utilities and manufacturers are closely collaborating with power utilities. 4.Main effort of universities is concentrated upon the theoretical aspects of network analysis and the means of stability improvement. Univer sities are doing research rather independently of industry unless inexceptional cases. 5.Universities are making a significant contribution to the exploration of new horizon of power systems engineering, namely, in the research on the social impact on the future of power system. 6.Current main interest of power systems reserch is centered around the stability problem and power system operation and control. Research activity in power system planning is rather low as compared to that in these two major fields. A similar statement holds for the analysis of electromagnetic transients and short circuit analysis. However a new research field is sprouting in the area of power system protection.

• 조명전기설비학회논문지
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• 제25권8호
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• pp.140-149
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• 2011

This paper deals with the impact analysis of the impedance change of 345/154[kV] power transformers on the KEPCO system's overall performance. Through the steady-state and dynamic analysis of power system, the maximum available impedance of power transformers were determined. Checking violation of short-circuit current ratings and transformer overload, parallel operation of power transformers, calculation of voltage variation ratio according to the impedance changes of power transformers are included in the steady-state analysis. In addition, transient and voltage stability analysis are also performed in the study. Available magnitudes to be able to change the impedance of the transformers in KEPCO system are finally determined in the paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.64-66
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• 2004

Due to the involvedness of power system, the analysis of power system is hard to make out. In some cases, visualized analysis results help to understand the power system effectively. In this paper, 3D graphic is used to visualize the power system, and chains of power system's changes are represented using the result of HyperSim, a real-time simulator. We represent states of each bus by changing height and colors of cylinder. The current of transmission lines and the angle of generators are represented by the size of pyramids and the drection of arrows respectively. Results of power system analysis are represented more easily and more intuitably using the visualization.

• 대한기계학회논문집A
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• 제28권6호
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• pp.717-725
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• 2004

A power generation systems are proposed to convert ambient mechanical vibration into electrical energy using cantilever-type piezoelectric materials. The vibration-based power device can be used for self-powered systems without batteries. This paper presents the theoretical analysis for the coupled equations of piezoelectric and structural motions and investigates the dynamic characteristics of the self-power system using transfer function method. The theoretical model is verified by the finite element analysis of the resonance frequency, the dynamic response of the structure and the sensor sensibility. Experimental results measured using a prototype system agree with the theoretical predictions. The system is shown to produce 34.5 ㎼ in average. Finally, we perform the optimal design for system variables to maximize output power.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.561-572
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• 2019

In the design criterion for the nuclear power plant piping system, the limit state of the piping against an earthquake is assumed to be plastic collapse. The failure of a common piping system, however, means the leakage caused by the cracks. Therefore, for the seismic fragility analysis of a nuclear power plant, a method capable of quantitatively expressing the failure of an actual piping system is required. In this study, it was conducted to propose a quantitative failure criterion for piping system, which is required for the seismic fragility analysis of nuclear power plants against critical accidents. The in-plane cyclic loading test was conducted to propose a quantitative failure criterion for steel pipe elbows in the nuclear power plant piping system. Nonlinear analysis was conducted using a finite element model, and the results were compared with the test results to verify the effectiveness of the finite element model. The collapse load point derived from the experiment and analysis results and the damage index based on the stress-strain relationship were defined as failure criteria, and seismic fragility analysis was conducted for the piping system of the BNL (Brookhaven National Laboratory) - NRC (Nuclear Regulatory Commission) benchmark model.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1901-1910
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• 2023

The safety-class (1E) digital control system (DCS) of nuclear power plant characterized structural multiple redundancies, therefore, it is important to quantitatively evaluate the reliability of DCS in different degree of backup loss. In this paper, a reliability evaluation model based on T-S fuzzy fault tree (FT) is proposed for 1E DCS of nuclear power plant, in which the connection relationship between components is described by T-S fuzzy gates. Specifically, an output rejection control system is chosen as an example, based on the T-S fuzzy FT model, the key indicators such as probabilistic importance are calculated, and for a further discussion, the T-S fuzzy FT model is transformed into Bayesian Network(BN) equivalently, and the fault diagnosis based on probabilistic analysis is accomplished. Combined with the analysis of actual objects, the effectiveness of proposed method is proved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.362-364
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• 2001

Every engineering discipline has, in recent year, felt the impact of computer-aided analysis and design Normally the studies of power system analysis by computer are load flow, short circuit and harmonic calculation, the amount the voltage deviates from motor starting, reliability and system stability. These studies are very important from the operating and planning points of power system. This paper presents analysis of load flow, short circuit current calculation, the effect for voltage deviation of induction motor starting and harmonic distortion in power system of continuous casting(C. C) plant. The resulting of analysis is applied the configuration and design engineering of power system.