• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.192-193
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• 2006

An AC electrical railroad system has rapidly changing dynamic single-phase load, and at a feeding substation, three-phase electric power is transformed to the paired directional single-phase electric power. There is a great difference in electrical phenomenon between the load of AC electrical railroad system and that of general power system. Electric characteristics of AC electrical railroad's trainload are changed continuously according to the traction, operating characteristic, operating schedule, track slope, etc. Because of the long feeding distance of the dynamic trainload, power quality problems such as voltage drop, voltage imbalance and harmonic distortion may also occur to AC electrical railroad system. These problems affect not only power system stability. but also power quality deterioration in AC electrical railroad system. The dynamic simulation model of AC electrical railroad system presented by PSCAD/EMTDC is modeled in this paper, and then, it is analyzed voltage drop and power quality for AC electrical railroad system both with single-Phase distributed STATCOM(Static Synchronous Compensator) installed at SP(Sectioning Post) and without.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.544-558
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• 2013

This paper proposes a simplified and efficient control scheme for Unified Power Quality Conditioner (UPQC) based on three-level (NPC) inverter capable to mitigate source current harmonics and compensate all voltage disturbances perturbations such us, voltage sags, swells, unbalances and harmonics. The UPQC is designed by the integration of series and shunt active filters (AFs) sharing a common dc bus capacitor. The dc voltage is maintained constant using proportional integral voltage controller. The shunt and series AF are designed using a three-phase three-level (NPC) inverter. The synchronous reference frame (SRF) theory is used to get the reference signals for shunt and the power reactive theory (PQ) for a series APFs. The reference signals for the shunt and series APF are derived from the control algorithm and sensed signals are injected in tow controllers to generate switching signals for series and shunt APFs. The performance of proposed UPQC system is evaluated in terms of power factor correction and mitigation of voltage, current harmonics and all voltage disturbances compensation in three-phase, three-wire power system using MATLAB-Simulink software and SimPowerSystem Toolbox. The simulation results demonstrate that the proposed UPQC system can improve the power quality at the common connection point of the non-linear load.

• 품질경영학회지
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• 제41권2호
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• pp.301-322
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• 2013

Purpose: This study aims to determine the needs of customers who use railroads as a mode of transportation and propose customer-oriented improvements in railroad technology by making connections between customer needs and railroad technology. Methods: We primarily used two methods for this study, AHP and QFD. First, AHP was used to evaluate the relative importance among the different components of railroad technology. Second, the QFD was applied to make a link between customer needs and railroad technology. Results: Railroad technology is largely divided into development, maintenance, and support. Empirical results showed the following improvement priorities in development, vehicle, system, line, signal/communication, power, and structure, in maintenance, vehicle, signal/communication, line, process, power, and structure, and in support, safety/precaution, management, environmental energy, operations/logistics, and station. Conclusion: Recognizing limitations in measuring the level of railroad technology when using the existing 'Technology Growth Model,' we used AHP and QFD to explore improvement directions for customer-oriented railroad technology. By offering customer-oriented services based on this study, railroad service providers will be able to acquire competitive advantage in the market.

• Journal of Power Electronics
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• 제8권1호
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• pp.51-59
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• 2008

This paper addresses several issues concerning the analysis, design, modeling, simulation and development of single-phase, single-switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis and design is presented for single-switch topologies, namely forward buck, flyback, Cuk, Sepic and Zeta buck-boost converters, with high frequency isolation for discontinuous conduction modes (DCM) of operation. With an awareness of modem design trends towards improved performance, these switching converters are designed for low power rating and low output voltage, typically 20.25W with 13.5V in DCM operation. Laboratory prototypes of the proposed single-switch converters in DCM operation are developed and test results are presented to validate the proposed design and developed model of the system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.501-503
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• 2005

The improvement of load following operation of the thermal power plant is influenced to the electrical quality. Analysis of boiler, turbine, and governor system, and the study of control algorithm are preceded. The thermal power plant is operated by various control systems. In the case of faulty governor system, it takes long days to solve the problem and impossible to repair the mechanism without outage. A non-planned out-age is taken into consideration because of economical power production. In this paper, to clear the continuous swings of an old turbine governor system(YEOSU #1), the trend, the control logic, and the hydraulic mechanism are analyzed, and then the control circuit with ADAPT function and the 1st order lag circuit are inserted and modified. After that, the power plant comes to automatic governor control operation.

• 한국건축시공학회지
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• 제8권2호
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• pp.121-129
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• 2008

Domestic exoteric construction market by opening of world construction market with recent FTA of rapidly change. On these time, need quality increase of construction to possess government official and international competitiveness of customer satisfaction by offering consumer building of good quality. Therefore, must establish direction to inspects and must advance forward formation government official's present actual conditions for building company's QI. This study is as following if summarize studying result of formation government official to improve quality in construction spot. First, formation's CEO will for QI need side improvement the formation government official enemy by important thing. Second, at checking activity and systematic action that participate of responsible persons cooperation enterprise space-time by complete charge department organization should be achieved. Third, complete charge department for quality control operation large size construction firm substantially formation Organizational well operate, but heavy hydrogen building company was construed by greatly unprepared misgovernment. AHP analysis result complete charge department is serious necessity, and the CEO under direct control organizational structure was construed by thing which can bring excellent effect in operation management side of quality business side and formation. Therefore, heavy hydrogen building company should does to occupy competitive power high position with tissue at active quality complete charge deputy.

• 한국항공우주학회지
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• 제44권6호
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• pp.512-519
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• 2016

FA-50 항공기 보조동력장치는 추력을 제외한 항공기의 동력을 생성하는 장치로 항공기 감항성 유지를 위해 매우 중요한 요소이다. 또한, 보조동력장치의 입구안내익은 로드압축기로 유입되는 공기 유량을 조절하여 적절한 공기량이 보조동력장치 내부로 공급되도록 유도하는 장치이다. 본 논문에서는 FA-50 항공기 보조동력장치 입구안내익 구동기어에서 발생한 문제점을 바탕으로, 발생원인, 고장탐구결과, 설계개선 내용을 기술하였으며, 개선된 연구에 대해 비행시험검증 결과를 함께 소개한다.

• 제어로봇시스템학회논문지
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• 제15권2호
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• pp.169-175
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• 2009

A new wire detection algorithm for power line inspection by a mobile robot has been proposed in this paper. There have been a lot of studies in order to support the high-quality electric power. For the high-quality power supply, it is necessary to investigate the power lines and insulators before the lines or insulators were disconnected or damaged. Although Korea Electric power Corp. has made many efforts for the quality improvement, it is not enough to inspect all the power lines by human inspectors. According to this problem, it is decided to replace the human operators by the power line inspection robot. When the robots are used for the inspection, there could be several advantages, for example, the working efficiency and the prevention of accident. And also the shortage of human power for dangerous jobs can be resolved. In this paper, as a part of the development of power line inspection robot, DICRO, the sensor fusion and fuzzy control algorithms are developed to detect the wire and slope of the wire. The effectiveness of the proposed algorithms is proved by the real experiments with DICRO which is under development so far.

• 신재생에너지
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• 제8권4호
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• pp.13-20
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• 2012

This paper describes a transformerless static synchronous campensator (STATCOM) system based on cascade H-bridge multilevel inverter with star configuration. It is designed not only for the dynamic and continuous compensation of the reactive power but also for the improvement of power quality of existing wind power plant. Especially, when the induction generator of wind turbine is directly connected to the grid, reactive power are occurred by exiting current. so a reactive power compensation system based on the cascade H-bridge multilevel STATCOM is proposed because the output power quality and controllability of reactive power are required by grid code in many different countries. Using various The proposed reactive power control strategy using a STATCOM is compared with the conventional scheme using fixed-size of capacitor bank through various simulation results.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.143-151
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• 2008

This paper presents the operation of Fuel Cell Distributed Generation(FCDG) systems in distribution systems. Hence, modeling, controller design, and simulation study of a Solid Oxide Fuel Cell(SOFC) distributed generation(DG) system are investigated. The physical model of the fuel cell stack and dynamic models of power conditioning units are described. Then, suitable control architecture based on fuzzy logic and the neural network for the overall system is presented in order to activate power control and power quality improvement. A MATLAB/Simulink simulation model is developed for the SOFC DG system by combining the individual component models and the controllers designed for the power conditioning units. Simulation results are given to show the overall system performance including active power control and voltage regulation capability of the distribution system.