• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.981-984
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• 1995

The feed system using ball screw is constructed by ball screw, support bering and LM guide, and servo system for driving ball screw. AC servo motr drives ball screw which was connected by coupling. In this study, a new axial direction dynamic modeling of ball screw driving system was developed, and forced vibraition test using the impact hammer was experimented. The simulation result is compared with experimental result, which defines the reliability of mathematical modeling.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.352-353
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• 2011

본 논문에서는 제주 한림 풍력발전소와 한림 변전소 간에 구축할 예정인 ${\pm}80kV$ 60MW HVDC 시스템의 절연 설계를 위해, 각 구성품의 절연 등급을 수 계산으로 설계하였고 PSCAD로 검증하였다. 각 부분의 절연설계 부분 중, 특히 AC측의 선로에 설치되어 고조파를 저감하는 AC Filter의 절연설계는 고려할 사항이 많다. AC측 선로의 사고, 임펄스 그리고 구성 소자인 인덕터와 커패시터의 설치 구성에 따라 AC Filter의 절연설계가 달라질 수 있다. 따라서 Filter 종류 및 주변 상황요소가 미치는 영향 등 모든 상황을 고려하여 모의하였고 수 계산으로 설계된 절연등급을 검증하였다.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.388-393
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• 1988

New circuit D-Q transformation concept is introduced to analyze AC converters such as inverters, rectifiers and cyclo-converters with ease. The equivalent linear time invariant circuit is obtained by substituting switches with equivalent turn-ratio variable transformers and changing balanced AC reactors into equivalent DC reactors combined by gyrators. This circuit enables us to utilize the powerful linear system analysis techniques such as Laplace transform otherwise which could not be applied to the time varying switching systems. Direct substitution of switches of DC converters with transformers is shown as a preliminary. Then the modeling procedure is shown for a controlled rectifier-inverter circuit. Finally an analysis example is proposed for a buck-boost inverter and the result is compared with the conventional approach. This approach is applicable to all AC converter families to determine the AC transfer functions and the DC operating points. It is identified that the switching systems are equivalent to the RLC filter circuits with transformers and gyrators.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.272-273
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• 2015

This paper analyze scenario of feeder wire fault that occurs in the AC feeding system considering train position. The fault location of AC feeding system is calculated by measuring impedance. However, in this way, estimation error can be occurred because of tie connection, boosting current, etc. Therefore, it's hard to find fault location, so that it is required to detailed circuit analysis according to fault location. We analyze the short circuit impedance values with respect to feeder wire fault according to a train position. In this paper, PSCAD is used for modeling and analysis of AC railway feeding system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.252-254
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• 2008

In this paper, the PSCAD/EMTDC modeling of JeJu AC power system with wind farms will be discussed. And the modelling of the synchronous generator, exciter, governor will also be defined in the JeJu power system by using the PSCAD/EMTDC. At the same time the fault analysis and the power flow analysis in JeJu AC power system are presented to demonstrate the JeJu AC power system can perfectly simulate the real JeJu power system function. Through the simulation using PSCAD/EMTDC we have gained the same results compared with the results accomplished by the PSS/E. so the validity of the modelling for the JeJu power system by using PSCAD/EMTDC is confirmed.

• Journal of Power Electronics
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• v.2 no.3
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• pp.212-219
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• 2002

A novel mode of parallel operation of a modular 3-phase AC-DC flyback converter for power factor correction along with tight regulation was recently analyzed and presented. The advantage of the proposed converter does not require expensive high voltage and high current devices that are normally needed in popular boost type 3-phase converter. In this paper tile detailed small signal analysis of the modular 3-phase AC-DC flyback converter is provided for control purpose and also experimental results are included to confirm the validity of the analysis.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.182-187
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• 1998

In this paper, the dynamic analysis and design of an AC to AC power supply with DC current link is presented. Despite many advantages of such a structure, its application in fixed frequency power supplies has received very little attention in the literature. Different issues related to dynamic analysis of the proposed system are considered. These include a simple averaging technique for modeling switching function generators, the concept of Internal Model Controllers, and necessary condition to avoid multiple crossing in ramp comparison methods. Theoretical and experimental results obtained from a DSP-based laboratory type setup are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1433-1442
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• 1998

The thesis presents a dual audio decoder which can decode both AC-3 and MPEG-2 bitstream. The MPEG-2 synthesis processi s optimized via FFT to establish the common data path with AC-'3s. A dual audio decoder consists of a DSP core which performs the control-intensive part of each algorithm and a common synthesis filter which perfomrs the computation-intensive part. All the components of the dual audio decoder have been described in VHDL and simulated with a SYNOPSYS tool. The software modeling of the DSP core was used for functional validation. After being synthesized using 0.6 .mu.m-3ML technology standard cell, the dual audio decoder was simulated at gate-level with a COMPASS tool for hardware validation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.8
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• pp.413-419
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• 2003

The paper presents a simulation model and analysis of a grid-connected variable speed wind energy conversion scheme (VSWECS) using the PSCAD/EMTDC software. The modeled system uses a variable speed drive, a fixed pitch angle, a synchronous generator as a wind generator and an AC-DC-AC conversion scheme, which facilitates the wind generation to efficiently operate under varying wind speed while connected to the distribution network. The power output of the WECS is controlled by the AC-DC-AC conversion scheme, the objective of which is to capture the maximum active power under varying wind conditions and to keep the voltage magnitude of the terminal bus at a specific level. Aerodynamic models are applied for a wind turbine model. An simulation analysis of the scheme in terms of its responding to wind variations is also presented.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.152-158
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• 2000

This paper deal with the experimental discussion about the impulse and AC dielectric strength of SF6 gas insulated transformer. Test sample is measured the dielectric breakdown voltage about modeling of the first and second section which is the weakest for surge voltage. The AC breakdown voltage is appeared 1.4 times than impulse breakdown voltage, so we can estimate that the impulse breakdown voltage is severe to AC breakdown voltage, and when the impulse is applied, in case of lmm tapping with Nomex paper, the characteristics of dielectric breakdown voltage is same to that in oil immersed transformer when SF6 gas pressure is 2.2kg/$cm^2$G.