• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.503-506
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• 2003

The photovoltaic generators have a nonlinear V-I characteristics and maximum power points which vary with the illumination levels and temperatures. Using maximum power point tracker with the intermediate converter can increase the system efficiency by matching the PV systems to the load. A novel MPPT control for photovoltaic system is proposed. The system input parameters are (dP, dI, and last incremental of duty ratio $L\deltaD$)and the output is the new incremental value (new ${\deltaD}$) according to the maximum power point under various illumination levels. Using fuzzy logic controller allows extracting the maximum power rapidly and without significant oscillations. Also FLC provides excellent features such as fast response, good performance and the ability to change the fuzzy parameters to improve control system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.761-764
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• 2003

Islanding phenomenon of a grid-connected photovoltaic (PV) power conditioning system (PCS) is said to occur if the PCS continues to power a section of the utility system after that section has been disconnected from the utility source. Since islanding creates hazards for personnel and equipment, PCSs are required to detect and prevent Et. In this paper, several islanding detection methods (IDMs) and reactive power variation method are described. Islanding test results for 9kW PCS are presented for verification.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.9-14
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• 2002

In front of the opening of electric distribution market in 2004. it is indispensable to have a proper estimation of power quality index and power quality cost calculation mechanism are indispensable to stabilize highly industrialized society and to vitalize the investment for electric power system. However, there were not enough measures to reflect the voltage characteristics such as voltage sags and interruptions which make electric load in unstable operation. This paper suggests power quality index(LDI) and power quality cost(LDC) which translate various kinds of voltage records into load drop index and cost based on aggregated load CBEMA curve. A sample calculation result shows that this method can produces the acceptable power quality index and costs for utilities and customers requirements.

• 한국통신학회논문지
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• 제27권6B호
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• pp.593-600
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• 2002

The reverse link signal power required for multimedia traffic in multipath faded single-code (SC-) and multi-code CDMA (MC-CDMA) systems is investigated. The effect of orthogonality loss among multiple spreading code channels is herein characterized by the orthogonality factor. The required signal power in both the CDMA systems is then analyzed in terms of the relative required signal power ratio of data to voice traffic. The effect of varying system parameters including spreading bandwidth, the of orthogonality factor, and the number of spreading codes are examined. Analytical results show that MC-CDMA users transmitting only a single traffic type require significantly more power than SC-CDMA users with only a single traffic type. On the other hand, MC-CDMA users transmitting multimedia traffic require power levels approximately identical to SC-CDMA users with multimedia traffic. The results can be used in the design of radio resource management (e.g., power allocation) scheme for wireless multimedia services.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1306-1308
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• 2000

A new ZVT PFC for using 3[KW] power amplifier is proposed. Generally, the single phase diode rectifier has been widely used in the SMPS of the conventional power amplifier. But this rectifier has occurred some problems which are the input power factor and current harmonics. To solve the above problems, in this paper, two topology is adopted. The one is the boost type PFC for improving the input power factor. The other is the ZVT resonant circuit for reducing the switching loss and stress. In this paper, the proposed topology is analyze designed to built the ZVT PFC for using 3[KW] power amplifier. In order to verify the circuit va finally, the PSPICE simulation and experiment results are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3169-3171
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• 1999

One of the important purposes o Telecommunications power plant operation is to supply safe power for maintaining the reliable communication services. Therefore, the power plant operation support system is generally used for efficient and maintenance of power plant without the increment of the operation and maintenance staffs. To operate and maintain a number of power plants efficiently, Korea Telecom developed centralized power plant monitoring and control system. In this paper, the system feature and main functions are described.

• 정보저장시스템학회논문집
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• 제6권2호
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• pp.57-62
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• 2010

This paper measured and analyzed the source of total power loss of an ODD of a notebook computer. It shows that the biggest power loss is the windage loss due to the friction between rotating disk and surrounding air. It measured the power loss by the tilting motion of a rotating disc which is originated from the unbalanced mass of the rotating disc or the squareness between case-rotor and shaft. The power loss of rotating disc due to tilting motion was also calculated by using FLUENT, and it was correlated with the measured one. This paper shows that the one of the effective methods to reduce the power loss of an ODD is to reduce the tilting motion of a rotating disc.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.175-177
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• 1999

This paper presents a prototype of visualization MMI of the Power System Phenomenon, specially synchronous machine dynamics and frequency deviations of power system for KEPCO's Enhanced Power System Simulator(KEPS)[1]. And some visualization designs of the Power System Phenomenons such as voltage stability, transient stability, SSR, Line overflow, and voltage deviations are presented. The prototype MMI has included the animations & 3D graphics presentations for synchronous machine rotor deviations and frequency deviations. So, a user can intuitively acquire the basic concepts of the power system oscillations. Finally, it will be scheduled to development of the various visualization MMI of the power system phenomenons for development and installation of KEPS.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.451-454
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• 2003

In this paper, the research trend and the sate-of-the-art of low cost motor drives are introduced with the recently increasing interest In various industrial applications, such as home appliance, hybrid electric vehicles, wind power systems, fuel cell systems, and etc. Based on this presented work, it is highly expected the power electronics technologies, which are accumulated through the last 20 years, can be effectively applied to actual application fields.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.143-145
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• 2006

This paper presents an overall control algorithm for a grid-connected wind-power generation system using a DFIG(doubly-fed induction generator) fed by back-to-back PWM converters. The control of DFIG is based on a stator-flux oriented vector control. The system enables not only fast and smooth synchronization but also high performance regulation of active and reactive power. Experimental results shows The feasibility of the control algorithm.