• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.280-286
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• 2006

The paper proposes a new protection algorithm for reliable operation of grid-interfaced PV system, which can flexibly interact with conventional protective schemes of power utility grid not only to prevent damages to utility or public persons and utility apparatus caused by malfunction or failure in distribution network protection system, but also to protect a PV system itself from faults or abnormal conditions of the network. The proposed algorithm is based on reclosing characteristics of the distribution system. As a network fault occurs, the new scheme determines whether it is momentary or permanent and responds in a pre-programmed way to the fault. For permanent outage, the proposed algorithm shuts down inverter's operations but monitoring system voltage and frequency at the point of common coupling with grid. When it comes to the momentary outage, Inverter starts stand-by operation mode so that it can be automatically connected to the grid without start-up procedures as soon as the system voltage and frequency returns into the normal operation range. In order to investigate' and evaluate the PV system operation, simulation study based on PSCAD/EMTDC has been carried out to verify the performance of the proposed protection scheme.

• 조명전기설비학회논문지
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• 제22권6호
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• pp.70-78
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• 2008

본 논문에서는 태양광 발전시스템을 전력회사의 실배전 계통에 적용하기 위한 시뮬레이션 모델링을 제시한다. 태양광 발전시스템이 실배전 계통에 미치는 영향을 해석하기 위하여, 태양광 발전시스템과 이를 실배전 계통에 적용한 시뮬레이션 모델을 PSCAD/EMTDC를 이용하여 모델링하였다. 태양광 발전 시스템의 적용 후 변전소로부터의 전력공급을 감소시킴으로써 부하 말단전압이 개선됨을 보였다. 또한 부하모선의 전압을 보상함으로써 부하 측의 전력품질이 개선됨을 보였다.

• 한국컴퓨터산업학회논문지
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• 제3권5호
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• pp.623-630
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• 2002

본 논문에서는 Legacy 데이터베이스 사이의 데이터 이동을 지원하는 XML Gateway를 설계하고 구현하는 방법을 제안한다. 이를 위해 XML 기술, Oracle XML Utility, 그리고 JDeveloper를 사용한다. 그리고 데이터를 추출하기 위해 XSQL 페이지를 사용하고, 이를 파싱하고 XSL 변환을 거친 후 XSQL 서블릿의 XMLHttpRequest 객체를 사용하여 저장한다. 구현된 시스템을 사용함으로써 업무담당자는 SQL＊Plus 도구를 이용하여 작업을 처리하지 않아도 되며 시스템이 제공하는 익숙한 Web 환경 인터페이스를 사용하여 데이터 이동을 편리하게 처리할 수 있게 되었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.670-673
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• 2000

This paper describes a new inverter active inverter between a photovoltaic(PV) array and single-phase utility that avoid the bulky input(60Hz) transformer on the AC side. The interface employs a pwm boost converter on the DC side followed by a pwm boost converter on the DC side followed by a pwm current-forced single-phase rectifier for injecting the power from the PV array into the mains. The current waveform at the AC side remains sinusoidal and exactly in phase at all time. The circuit also has the advantage of requiring fewer switching device than high-frequency link system. This paper describes modeling of PV array and new system topology. Simulation results on the performance of the connection are also presented.

• Journal of Power Electronics
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• 제14권2호
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• pp.324-340
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• 2014

Recent developments in power electronics technology have spurred interest in the use of renewable energy sources as distributed generation (DG) generators. The key component in DG generators is a grid-connected inverter that serves as an effective interface between the renewable energy source and the utility grid. The multifunctional inverter (MFI) is special type of grid-connected inverter that has elicited much attention in recent years. MFIs not only generate power for DGs but also provide increased functionality through improved power quality and voltage and reactive power support; thus, the capability of the auxiliary service for the utility grid is improved. This paper presents a comprehensive review of the various MFI system configurations for single-phase (two-wire) and three-phase (three- or four-wire) systems and control strategies for the compensation of different power quality problems. The advances in practical applications and recent research on MFIs are presented through a review of nearly 200 papers.

• Journal of Computing Science and Engineering
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• 제4권2호
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• pp.153-172
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• 2010

Wireless mobile multimedia communications have been greatly increased in the number of users, diversity of applications and interface technologies. Wireless mobile networks are being evolved and integrated into IP based core network, so it is necessary to provide sufficient QoS (Quality of Service) mechanism to provide enhanced user's satisfaction. In this paper, we propose a new adaptive QoS mechanism based on utility function borrowed from the field of microeconomics, call setup and handover signaling mechanism integrating QoS and mobility management. Through a simulation, we show that adaptive resource allocation based on user preferences can be realized in the wireless mobile network with some considerations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.309-312
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• 2002

For the purpose of more effective simulation of the utility interactive WPGS(Wind Power Generation System) the SWRW (Simulation method for WPGS using Real Weather condition) is used in this paper, in which those of three topics for the WPGS simulation. user-friendly method, applicability to grid-connection and the utilization of the real weather conditions, are satisfied. The simulation of the WPGS using the real weather condition including components modeling of wind turbine system is achieved by introducing the interface method of a non-linear external parameter and FORTRAN using PSCAD/EMTDC. The simulations of steady-state and transient-state are performed effectively by the introduced simulation method. The generator output and current supplied into utility can be obtained by the steady-state simulation, and THD can be achieved by analyzing the results as well. The transient - state of the WPGS can be analyzed by the simulation results of over cut-out wind speed.

• 한국가구학회지
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• 제15권1호
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• pp.17-25
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• 2004

In this study, web-sites of home furniture business in Korea have been investigated to understand the conditions for the activation of e-marketing activities. Contents of seven businesses that have been selected for the study was analyzed in three aspects: utility, value of entertainment and structure. Result of the study showed that in the aspect of utility, the web-sites were desired to provide customers with more detail and diverse information rather than simply present description and prices of the products for the purpose of promotion. In the aspect of entertainment value, it was found that the information on the web-sites lacked diversity, originality and expertism, thus requiring for an independent contents development in a way that arouse interest in the web-sites. In the aspect of structure, the web-sites were desired to have interface easy to access and with strong absorption force. To sum up, the examined web-sites were required to diversify their standardized contents in a way that reflects identity of the business and meets diverse needs of customers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.466-470
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• 1991

In this paper, full bridge inverter with IGBT is proposed. By Controlling phase angle difference between 2 arms, PWM controlled high frequency link inverter has VVVF capability. For the simplicity, flexibility and compactness of control circuit, 16 bit single chip microcontroller 8797 BH is used and its characteristic is examined through experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.273-278
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• 1988

This paper represents the computer application techniques of initial and modification machining for dies with 3-dimensional scluptured surfaces. All procedures from die design to die machining and measurement are covered. The component of modelling is data management and modification (extrapolation and smoothing), surface modelling, and nc program preparation. Also this paper introduces the utility for successful and efficient operation of system such as map generation, data communication, tool path verification, contour map generation, graphic processing of extrapolation and smoothing results, and CAD/CAM system interface. Examples are given to illustrate the modelling.