• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.415-416
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• 2007

본 논문에서는 대역 제한된 색도 신호에 의해 발생하는 컬러번짐 현상을 TV 수신단이나 MPEG 디코더에서 효과적으로 개선하는 방법을 제시한다. 제안하는 컬러 번짐 개선 알고리즘은 비디오 신호에 포함된 색도 신호의 천이를 개선하기 위하여, 색도 신호의 일정 윈도우 영역에 존재하는 주변 화소들의 국부 최대값 및 국부 최소값을 바탕으로 얻어낸 계단 신호를 사용한다. 대역 제한된 색도 신호에서 이웃에 존재하는 화소들간의 색도 차를 계산하여 에지 특성을 분석하고 계산된 색도 차를 바탕으로 입력 신호와 계단신호와의 공간 적응적 가중치를 결정한다. 실험 결과에서는 제안하는 컬러 번짐 개선 알고리즘이 컬러 번짐 효과를 효과적으로 제거하여 선명하면서도 자연스러운 영상을 얻어내는 것을 확인할 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.685-688
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• 1998

In this research project, two aspects of small signal stability are studied: improvement in Hessenberg method to compute the dominant electromechanical oscillation modes and siting FACTS devices to damp the low frequency oscillation. Fourier transform of transient stability simulation results identifies the frequencies of the dominant oscillation modes accurately. Inverse transformation of the state matrix with complex shift equal to the angular speed determined by Fourier transform enhances the ability of Hessenberg method to compute the dominant modes with good selectivity and small size of Hessenberg matrix. Any specified convergence tolerance is achieved using the iterative scheme of Hessenberg method. Siting FACTS devices such as SVC, STACOM, TCSC, TCPR and UPFC has been studied using the eigen-sensitivity theory of augmented matrix. Application results of the improved Hessenberg method and eigen-sensitivity to New England 10-machine 39-bus and KEPCO systems are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.791-794
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• 1995

This paper introduces a new approach to adaptive control using a combination of direct, indirect and variable structrure method. A new variable structrue input is derived to counteract the effects of disturbances. Direct input is used to have fast response and indirect input improves the transient behavior of the system. Computer simulation results illustrate the very satisfactory performance of the proposed algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.485-487
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• 2003

본 논문은 기설 WSI제 CVT에 대해 전자 과도해석 프로그램((EMTP : Electromagnetic Transient Program)을 통한 모의실험으로 철공진현상 제동저항 크기($0.5{\Omega}$)를 선정하고, 기설 154kV 및 345kV CVT의 철공진방지회로를 제동저항 단독취부 형태에서 과포화리액터와 제동저항을 직렬회로로 구성하여 취부하는 방식으로 개선한 후 실증시험 및 현장적용 시험을 통해 CVT 쳔공진현상 제동여부 확인 및 외함온도 변화추이 비교하여 개선효과를 제시함으로써 WSI제 CVT 고장예방에 기어코자 한다.

• Plant Resources
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• 제8권2호
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• pp.87-90
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• 2005

In tobacco, in vitro pollination has been successfully applied to overcome interspecific incompatibility. The use of this technique will make it possible to introduce DNA into pollen tubes just before fertilization. In this study, we showed improvement of the efficiency of in vitro self-pollination and introduction of foreign genes into pollen tubes by the method of polycation. A plasmid harbouring the GUS gene was introduced into pollen grains and pollen tubes, which had incubated on pollen germination medium(PGM), by polyornithine method. Transient expression of the GUS in pollen grains and pollen tubes that were treated with 0, 2, 5 and $10{\mu}g/m\ell$ DNA was observed. In results, combination of the techniques of polyornithine and in vitro pollination was efficient new technique for genetic transformation through fertilization processes.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1995년도 추계학술대회 학술발표 논문집
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• pp.25-28
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• 1995

A Practical application of self-tuning fuzzy controller to a multi-input multi-output complex system of a vehicle engine is investigated. The ovjective is to design a controller to improve the transient performance in torque and RPM mode changes. For the performance improvement in the multivariable comples system, the self-tuning function of internal parameters is essential and practical. The measured output variables using different control schemes are compared the advanteges of the self-tuning fuzzy logic controller are better output performances and the effectiveness in the controller design using many parameters.

• 전기학회논문지
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• 제61권5호
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• pp.657-663
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• 2012

Recently, by increasing of devices which are sensitive to power quality, the deterioration of power quality has been accelerated. For this reason, the social and economic losses are increased. So not only correct measurement and evaluation, but also countermeasure for improvement of power quality is surely necessary for both electric power supplier and consumer. In this paper, the discrimination algorithm for events and variation occurred in distribution systems using S-transform is proposed. Firstly, we review for events and variations that occur in distribution system. Next, we simulate events and variations on various conditions using ElectroMagnetic Transient Program(EMTP). For the simulation, the IEEE 13 Node Test Feeder and KEPCO's distribution system is modeled. Finally, for the analysis, a modified wavelet transform known as S-transform is adopted to find out the characteristics of each events and variations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.525-529
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• 2001

A pulse frequency control(PFM) method for single-phase SEPIC-type rectifier is described in this paper. In the SEPIC rectifier, a relationship between the output power and the respective switching frequency is investigated to establish the control scheme of PFM. The propsed control method is provided with a feed-forward control loop of the output load as well as a feed-back control loop of the output voltage. The simulation results show good dynamic responses and unity power-factor operation.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.693-696
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• 2011

In this work, an exponentially tapered microstrip antenna was implemented using a resistive loading technique in order to suppress the internal reflections. The inductive loading was realized by introducing slits on the antenna to improve radiation efficiency. Compared with a resistive-loaded antenna, the proposed antenna had an average improvement of about 6.2% in radiation efficiency within the range of 2-10.5 GHz. In addition, the highest peak of the radiated short pulse from the proposed antenna became 45% greater than that of an antenna with resistive loading only.

• 전력전자학회논문지
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• 제22권2호
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• pp.181-184
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• 2017

This study analyzes the turn-on and turn-off transients of a metal-oxide-semiconductor field-effect transistor (MOSFET) with high-switching frequency systems. In these systems, the voltage distortion becomes serious at the output terminal of a Vienna rectifier by the turn-off delay of the MOSFET. The current has low-order harmonics through this voltage distortion. This paper describes the transient of the turn-off that causes the voltage distortion. The algorithm for reducing the sixth harmonic using a proportional-resonance controller is proposed to improve the current distortion without complex calculation for compensation. The reduction of the current distortion by high-switching frequency is verified by experiment with the 2.5-kW prototype Vienna rectifier.