• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.319-322
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• 2005

This paper describes practical tuning methods and testing of a digital PSS, which uses both frequency and power, with the 220MVA Chungpyung P/P #1 in the KEPCO system to enhance the damping of local modes. In the first step, the objective phase of PSS is computed through a phase leading function to provide compensation between the exciter reference point and the generator air-gap torque before tuning the PSS's time constants. In addition, eigenvalue analysis was used to determine a range of PSS's gain, whichis the more useful for field testing rather than a single gain value. The Real-Time Digital Simulator was used to verify safe operations of the PSS in the presence of disturbances, such as AVR step and three phase fault.

• The Journal of the Acoustical Society of Korea
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• v.31 no.2
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• pp.87-92
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• 2012

In this paper, a robust feature compensation method to deal with the environmental mismatch is proposed. The proposed method applies energy based weights according to the degree of speech presence to the Mean subtraction, Variance normalization, and ARMA filtering (MVA) processing. The weights are further smoothed by the moving average and maximum filters. The proposed feature compensation algorithm is evaluated on AURORA 2 task and distant talking experiment using the robot platform, and we obtain error rate reduction of 14.4 % and 44.9 % by using the proposed algorithm comparing with MVA processing on AURORA 2 task and distant talking experiment, respectively.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.866-867
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• 2008

Among many tests to verify the characteristics of power system apparatus, the short circuit test is performed to verify the performance characteristics of the apparatus under the short-circuited power system. The verification of the short-circuit performance is inevitable for the reliability of power system and the safety of the operator around. The short circuit performance test requires the suitable power source and Korea Electrotechnology Research Institute has 4000 MVA, 500 MVA short circuit generators for the short circuit performance test. This paper will study on the parameters of short-circuit generator and the estimation of them.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.181-184
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• 2006

FACTS 기술은 송전계통에 전압원 인버터를 설치하여 모선 전압과 전력조류를 제어하므로 송전용량 증대 및 계통 안정도 향상을 가능케하는 신기술이다. 국내에서는 2003년 최초의 FACTS Pilot Plant인 80MVA UPFC가 154kV 강진 변전소에 설치되었다. UPFC는 STATCOM과 SSSC가 DC 커패시터를 통하여 결합된 구조로 되어 모선전압과 유효/무효전력 조류의 독립적인 제어가 가능하며 계통 운전 상황에 따라 STATCOM과 SSSC의 단독운전 또한 가능하다. 따라서 STATCOM 및 SSSC 단독운전시의 계통영향에 대한 분석이 필요하다. 본 논문은 EMTDC 모델을 이용하여 현재 운전중인 강진 변전소 UPFC의 직렬 운전모드인 40MVA SSSC의 제어특성과 운전효과 분석에 대하여 기술하였다.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.203-205
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• 2003

Parallel wounded windings with BSCCO-2223 HTS tape for 1MVA HTS transformer were designed and prototype windings were fabricated in double pancake type. The parallel HTS tapes were transposed between the pancakes via non-superconducting joints because it is hard to make transpositions inside the pancake windings. The prototypes were wound using copper tape with same size as BSCCO-2223 tape, which will be used in 1MVA HTS transformer. The windings will be used for high voltage test and insulation test of the transformer Parallel HTS windings are going to be fabricated and tested for current distribution in near future.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1692-1695
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• 1997

This paper describes the relationship between the various non-destructive parameters and the breakdown voltage for the 17 kV, 300 MVA and the 22 kV, 500 MVA generators stator bars with polyester and epoxy/mica insulation respectively. Also, this study reports the results of an investigation into the factors which can assess the insulation condition of generator stator winding. Furthermore, a new parameter, Partial Discharge Index(PDI), is introduced as the valuable parameter for the assessment of insulation condition. The ratio between partial discharge increment and the stepwise voltage increment from the Discharge Inception Voltage (DIV) at the characteristic or resonant frequency band shows the close relationship between the breakdown voltage and PDI.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.37-50
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• 2000

We are concerned with estimating the average performance of a re-entrant line with single-job machines and batch machines. The system has multiclass jobs, which will be processed in predetermined routes. An analytical approach may be intractable since the system would not be modeled by product form queueing networks due to the inclusion of batch machines and the consideraton of multiclass jobs which have different processing times. We propose an approximation method based on the Mean Value Analysis(MVA). Our method obtains the mean walting time in each buffer of a workstation and the mean cycle time using the MVA and heuristics. numerical experiments show that the errors of our method are within 5% compared with simulation.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.491-493
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• 2003

전력계통의 유연하고 안정적인 운용을 위한 인버터형 FACTS 기기의 국내 적용에 대한 연구 결과를 토대로 국내 154kV 계통에 적용되는 80MVA급 UPFC pilot plant project가 수행되었다. Project의 결과물로써 80MVA급 UPFC가 강진-장흥 154kV 계통에 제작, 설치되었다. 강진 변전소 UPFC는 각종 성능 시험 및 시운전 절차를 성공적으로 완료하였으며 현재는 병렬 인버터에 의한 강진 모선의 전압 제어 및 직렬인버터에 의한 강진-장흥간의 조류 제어 기능을 수행하며 상용 운전되고 있다.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.528-530
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• 2003

UPFC Pilot plant project의 결과물로써 설계, 제작된 80MVA급 UPFC(Unified Power Flow Controller)는 현재 강진변전소 강진-장홍 154kV 선로에 설치되어 commissioning 시험을 완료하고 시험 운전되고 있다. UPFC는 기존에 수동적으로 제어하였던 선로의 전압, 임피던스 및 위상각을 능동적으로 제어함으로써 전력공급의 신뢰성 및 유연성을 높일 수 있다. 이러한 기능을 갖는 UPFC의 시험 운전을 통하여 UPFC의 기기자체의 성능을 검증하고 기기의 운전 영역의 변화가 인근의 계통에 미치는 영향에 대하여 조사하였다.

• JOURNAL OF ELECTRICAL WORLD
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• s.394
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• pp.46-51
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• 2009

국내 수도권 전력망의 전압 안정도 향상과 융통전력 증대로 인한 혼잡비용 저감을 위하여 한전 전력연구원과 (주)효성은 2005년부터 345kV 100MVA STATCOM을 국산화 개발하고 수도권 중추 변전소중 하나인 미금 변전소에 설치하여 실증운전을 수행하였다. 본 설비는 IGCT 전력소자를 이용하여 전압원 인버터의 고성능화, 소형화를 이룩하였으며, 설계, 제작, 설치, 운영 및 IT 기술을 이용한 운영방안의 고도화 등 제반사항을 국내 기술로 개발한데 큰 의의가 있다. 본 STATCOM은 2010년말까지 실증운전을 통한 신뢰성 검증후 2011년 본격적인 상용운전을 시작할 예정이다.