• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1480-1484
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• 2003

This paper presents the design and development of network for housing estate security system. The system can cover up to 961 houses which can be up to 1,200 meters long transfer rate of 9,600 bps. This system uses checking and warning the abnormal situation. More over this system has ability to control switch on/off the electrical equipment in the house via AC line control system. The system consists of 4 parts. The first part is a security system of each house using MCS-51 microcontroller as a central processing unit scan 32 sensors and control 8 appliances and send alarm. The MCS-51 microcontroller received control signal via telephone used DTMF circuit. The second part is distributed two levels master/slave network implementing after RS-485 serial communication standard. The protocol its base on the OSI (Open Systems Interconnection) 7 layers protocol model design focus on speed, reliability and security of data that is transferred. The network security using encrypt by DES algorithm, message sequence, time stamp checking and authentication system when user to access and when connect new device to this system. Flow control in system is Poll/Select and Stop-and-Wait method. The third part is central server that using microcomputer which its main function are storing event data into database and can check history event. The final part is internet system which users can access their own homes via the Internet. This web service is based on a combination of SOAP, HTTP and TCP/IP protocols. Messages are exchanged using XML format [6]. In order to save the number of IP address, the system uses 1 IP address for the whole village in which all homes and appliance in this village are addressed using internal identification numbers. This proposed system gives the data transfer accuracy over 99.8% and maximum polling time is 1,120 ms.

• 조명전기설비학회논문지
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• 제14권3호
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• pp.49-58
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• 2000

본 논문에서는 FACTS(Flexible AC Transnission System)로 분류되는 여라 기기중 기존의 전압제어 및 무효 전력보상기들이 가지고 있는 바속응성과 불연속성 문제를 해결해줄 수 있는 정지형 무효전력 보상가(Static Var Compensator : SVC)를 포함한 전력계통에 신경회로망 제어기를 적용하여 안정화에 관하여 연구하였다. 제안된 신경회로망 제어기는 오차와 오차변화량을 입력하는 오차역전과 학습 알고리즘을 사용하고, 학습시간올 단축하기 위해 모멘텀 방법을 사용하였다. 제안된 방법의 강인섬을 입증하기 위해 중부하시 및 정상부하시에 초기 전력을 변동시킨 경우와 초기에 회천자각을 변동시킨 경우에 대하여 시스렘의 회전자각, 각속도 편차 특성 및 단 자전압의 동특성을 고찰하여 다른 시스템보다 응답특성이 우수합을 보였다.

• 전기학회논문지
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• 제65권1호
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• pp.158-164
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• 2016

That's the reason why LED lighting has to employ AC power inlet. However, LED is a kind of diode, semiconductor, it's driven by DC power. With whis reason all of LED lighting should have AC/DC converter in its systems. This converter causes energy loss, it's the target for lesson the energy loss. To reduce this energy loss, DC power distribution structure can be used. LED lighting system using LVDC is a kind of DC power distribution structure, but LVDC has severe voltage drop which makes non-uniform brightness in lighting system. In this paper, we suggest a novel structure for the uniform brightness in LVDC LED lighting system using IoT based network system. The constructed test-bed system of suggested structure shows this structure can con control the brightness with uniformity.

• 대한전기학회논문지:전력기술부문A
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• 제52권11호
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• pp.632-638
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• 2003

Modern power systems are very complex and to model them completely is impractical for electromagnetic transient studies. Therefore areas outside the immediate area of interest must be represented by some form of frequency dependent equivalent. The s-domain rational function form of frequency dependent equivalent does not need refitting if the simulation time-step is changed in the electromagnetic transient program. This is because the s-domain rational function coefficients are independent of the simulation time-step, unlike the z-domain rational function coefficients. S-domain rational function fitting techniques for representing frequency dependent equivalents have been developed using Least Squares Fitting(LSF). However it does not suffer the implementation error that exited in this work as it ignored the instantaneous term. This paper Presents the formulation for developing 1 Port Frequency Dependent Network Equivalent(FDNE) with the instantaneous term in S-domain and illustrates its use. This 1 port FDNE have been applied to the CIGRE Benchmark Rectifier test AC system. The electromagnetic transient package PSCAD/EMTDC is used to assess the transient response of the 1 port (FDNE) developed with Thevenin and Norton Equivalent network. The study results have indicated the robustness and accuracy of 1 port FDNE for electromagnetic transient studies.

• 전기학회논문지
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• 제62권12호
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• pp.1678-1687
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• 2013

This paper describes a prototype of 3-phase 3.3kV/220V 6kVA modular semiconductor transformer developed in the lab for feasibility study. The developed prototype is composed of three single-phase units coupled in Y-connection. Each single-phase unit with a rating of 1.9kV/127V 2kVA consists of a high-voltage high-frequency resonant AC-DC converter, a low-voltage hybrid-switching DC-DC converter, and a low-voltage hybrid-switching DC-AC converter. Also each single-phase unit has two DSP controllers to control converter operation and to acquire monitoring data. Monitoring system was developed based on LabView by using CAN communication link between the DSP controller and PC. Through various experimental analyses it was verified that the prototype operates with proper performance under normal and sag condition. The system efficiency can be improved by adopting optimal design and replacing the IGBT switch with the SiC MOSFET switch. The developed prototype confirms a possibility to build a commercial high-voltage high-power semiconductor transformer by increasing the number of series-connected converter modules in high-voltage side and improving the performance of switching element.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.717-721
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• 2003

Two non-conventional HVDC converter arrangements are compared. These include the Capacitor Commutated Converter (CCC) in which series capacitors are included between the converter transformer and the valves, and the Controller Series Capacitor Converter (CSCC), based on more conventional topology, in which series capacitors are inserted between the AC filter bus and the AC network. Results show that both options have comparable steady state and transient performance. Danger of ferroresonance with the CSCC option is eliminated by controlling the amount of series compensation. The dynamic performance simulations is peformed by PSCAD/EMTDC

• 전기학회논문지
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• 제61권1호
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• pp.16-21
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• 2012

The growth in IT industry has brought a corresponding rise in the number of connected digital devices in the distribution network. These digital loads lead to AC to DC conversion losses in order to supply power to them. The more the renewable energies and plug-in electrical vehicles penetrated our lives, the more the electrical losses are caused by AC to DC conversion process. Hence, this paper suggests the methodology for evaluating the amount of power supplied according to the ratio of DC power supply and performs an economic analysis of DC distribution system considering grid parity. In here, the cost of carbon emission reduced by renewable energy is also concerned.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.476-477
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• 2007

This paper described the partial discharge (PD) measurement techniques for diagnosing gas-insulated switches in overhead power distribution system. A capacitive voltage probe to detect PD pulse was designed and fixed on the surface of a bushing. We also designed a coupling network to attenuate AC voltage by 270 dB, and a low-noise amplifier having the gain of 40 dB and 500 kHz~20 MHz 3 dB. From the calibration, it was calculated that the sensitivity of the measurement system was 0.94mV/pC. In the application experiment, we could measure a PD pulse of 45 pC.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.541-544
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• 2004

지식정보사회로의 변천은 우리의 삶을 보다 편리하고 윤택하게 해주고 있지만 미처 예상하지 못했던 부작용 또한 적지 않게 발생하고 있어 이에 대한 해결방안을 모색하는 것이 시급한 실정이다. 아직 인성이 발달되지 못한 청소년들이 정보통신망을 통해서 유통되고 있는 수많은 음란물과 폭력물과 같은 유해정보에 무방비상태로 노출되고 있는 것도 정보화사회의 대표적인 역기능 중의 하나라고 할 수 있다. 이 문제점 해결을 위해 본 논문에서는 사이트 상에서 제공되어지는 내용을 AC 머신을 이용하여 유해 단어를 추출하고 유해 정보 데이터베이스를 이용해서 유해 단어에 가중치를 부여했다. 그 결과로 유해 정보를 포함한 사이트는 90%의 차단률을 보여 효율적인 시스템으로 판명되었다.

• KEPCO Journal on Electric Power and Energy
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• 제5권4호
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• pp.275-286
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• 2019

본 논문은 DC (Direct Current) 배전망 혹은 DC 마이크로그리드 운영을 위한 실시간 DC 계통해석 응용프로그램의 개발에 대한 내용을 다룬다. 응용프로그램은 중앙 에너지 관리시스템(EMS: Energy Management System)에 탑재되어 운영자에게 실시간으로 운영 솔루션을 제공한다. DC 배전계통을 해석하기 위한 프로그램의 구성 및 시퀀스를 제안한다. 각 프로그램의 알고리즘과 AC 계통 프로세스와의 차이점을 분석한다. 한국전력공사 고창전력시험센터 내 DC 배전망 실증사이트를 소개하고, EMS 구축 내용을 기술한다. 개발된 DC 계통해석 응용프로그램을 실증 사이트 EMS에 탑재하여, 검증 시험을 수행한다. DC 배전망 전압 제어를 위한 시험 시나리오를 구성에 대해 논한다. 마지막으로 실증시험 결과 측정 데이터, 응용프로그램 결과 데이터를 PSCAD/EMTDC를 이용한 오프라인 시뮬레이션 결과값과 비교 분석하여 정합성을 검증한다.