• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.536-537
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• 2010

If DC voltage adjustment can be controlled very easily, it is much more effective rather than AC in transmission efficiency. The main reason why DC is more effective than AC, DC has the same role as the 70[%] of AC whenever the same power send. In addition, AC streams the surface of electrical wire, but DC streams overall of electrical wire. Digital load, which is operated by DC, has increased in modern times. The step of convert of AC-DC has to be reduced. When we turn the dispersed AC-DC converters into the concentrated AC-DC converter, it can improve the effective of the whole system. Further more, if digital society develops more than now and the time of electric vehicle comes, the need of DC will increase much more than these days. This paper suggests that DC output of distributed power source and high efficient 3 phase PWM converter can control the adjustment of output voltage, harmonic restraint, power factor improvement and dump power.

• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.474-483
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• 2011

Solid-state fault current limiters (SSFCL) in power systems are alternative devices to limit prospective short circuit currents from reaching lower levels. Fault current limiters (FCL) can be classified into two categories: R-type (resistive) FCLs and L-type (inductive) FCLs. L-type FCL uses an inductor to limit fault level and is more efficient in suppressing voltage drop during a fault. In contrast, R-type FCL is constructed with a resistance and is more effective in consuming the acceleration energy of generators during a fault. Both functions enhance the transient stability of the power system. In the present paper, a novel SSFCL is proposed to enhance power system transient stability and power quality. The proposed SSFCL uses both functions of an L-type and R-type FCL. SSFCL consists of four diodes, one self-turn-off IGCT, a current-limiting by-pass inductor (L), and a variable resistance parallel with an inductor for improvement of power system stability and prevention of over-voltage across SSFCL. The main advantages of the proposed SSFCL are the simplicity of its structure and control, low steady-state impedance, fast response, and the existence of R-type and Ltype impedances during the fault, all of which improve power system stability and power quality. Simulations are accomplished in PSCAD/EMTDC.

• 한국철도학회논문집
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• 제13권6호
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• pp.559-564
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• 2010

본 논문은 동력 집중식 철도차량에서 전력변환장치로서 객차용 전원공급장치의 전력품질을 향상시키기 위해 보완된 필터설계를 제안한다. 먼저, 필터설계를 위해 객차용 전원공급장치와 연결된 변압기의 출력전력 파형을 측정하였다. 실험 및 시뮬레이션 결과를 통해 스위칭 기법은 개선된 특정고조파 소거 펄스폭 변조이고 스위칭 주파수는 300Hz임을 추정하였다. 따라서 추정된 파라미터를 바탕으로 전력품질을 향상시키기 위해 필터를 설계하였다. 시뮬레이션 결과 전체적으로 고조파의 크기가 감소함을 확인하였다.

• 산업공학
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• 제17권1호
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• pp.93-103
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• 2004

Service importance has been growing increasingly as competition element of enterprises according to going on rapid softness, information and knowledge of industrial infrastructure recently. Quality management system that implemented in manufacturing sector have been spreading rapidly to service company, but the company performing pure engineering service only in construction fields performed mainly the evaluation on the operational aspect such as degree of implementation of the established system because it is difficult to objective evaluation on the activity of the established quality management system or quality assurance system. This study would like to make on offer the improvement points based on the evaluation of service quality and the itself evaluation result through the questionnaire on the service offerers and customers using the pre-qualified SERVQUAL model in establishment of the improvement goal of the company. According to the result of this study, it is analyzed a gap and required to establish a counter-plan to correct many gaps discovered between the real offered level and the expect level of custom.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1584-1587
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• 2005

Although the picture quality of today's displays is very good already, a continuous improvement is desirable as the new larger display sizes increase the visibility of artifacts. A contributing factor for picture quality enhancement through smart video processing and algorithm design is the information gathered from video statistics. Interesting parameters gathered from video statistics are e.g. the image- and display load, the usage of the color gamut, the estimated power consumption and the occurrence of static image parts. Examples of applications that can benefit from video statistics are power calculations, color gamut mapping algorithms, dynamic backlight control for LCD panels and LED backlights for LCD panels.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.143-148
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• 1998

A dynamic electrical parameter monitoring device was designed to simultaneously record the instantaneous value of voltage, current, power, and resistance during spot welding. The data obtained using this technique have been analyzed in term of the relationships of these parameters to the phenomena occuring during the formation(surface break-down, nugget formation and mechanical collapse) of spot weld. Finally, a database implementation is undertaken to develop techniques for improving weld quality of the resistance spot welder.

• 전력전자학회논문지
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• 제5권3호
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• pp.276-284
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• 2000

저항 스폿용접기에서 용접품질의 보증은 오래 계속 되어온 문제이었다. 본 논문에서는 용접품질과 전극분리와의 관계를 조사하였으며 전극분리가 하나의 제어변수로써 사용될 수 있음을 실험적으로 입증하였다. 피드백신호로서 전극분리를 이용한 퍼지제어에 기초를 둔 용접품질개선을 제시하였다. 저항 스폿용접기의 용접품질은 인장전단강도시험과 같은 파괴적인 검사에 의해 증명되었다. 시험결과는 퍼지 제어기를 이용한 전극분리 제어의 성능이 종래의 정전류 제어와 비교하여 훨씬 더 우수하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.371-372
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• 2014

This review focuses on grid-connected technology for distributed energy resources(DER). The grid-connected technology is categorized into three classifications: 1) protection function; 2) power quality improvement function; 3) grid stabilization fuction. Grid codes comparison of Japan, USA, EU and Korea is also described in the paper.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.281-282
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• 2011

본 연구에서는 DC마이크로그리드의 전력품질을 향상시키기 위한 에너지 저장장치의 Power Balancing 제어기법에 대하여 기술하고 있다. 제안하는 시스템의 동작 타당성을 체계적으로 분석하기 위해 PSCAD/EMTDC 소프트웨어를 이용한 마이크로그리드 모델을 개발하였으며 여러 사례 적용에 대한 모의실험을 통해 제어기법의 타당성을 검증하였다.

• 한국철도학회논문집
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• 제2권4호
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• pp.32-39
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• 1999

A flywheel system which can compensate electric power is presented. The designed system has a capability of providing real and imaginary power instantaneously as well as storing energy. In this paper, a control algorithm is designed. The designed algorithm is to control the secondary side current of the wound rotor induction motor using voltage-based PWM inverter. The flywheel system has advantages in converter size and power quality improvement comparing to the conventional system.