• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.67-75
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• 2011

The development of electric vehicle power electronics system control, composed of DC-AC inverters and DC-DC converters, attract much research interest in the modern industry. A DC-AC inverter supplies the high-power motor torques of the propulsion system and utility loads of electric vehicles, whereas a DC-DC converter supplies the conventional low-power and low-voltage loads. However, the need for high-power bidirectional DC-DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. The nonlinear control of power converters is an active research area in the field of power electronics. This paper focuses on the use of the fuzzy sliding mode strategy as a control strategy for buck-boost DC-DC converter power supplies in electric vehicles. The proposed fuzzy controller specifies changes in control signals based on the surface and knowledge on surface changes to satisfy the sliding mode stability and attraction conditions. The performance of the proposed fuzzy sliding controller is compared to that of the classical sliding mode controller. The satisfactory simulation results show the efficiency of the proposed control law, which reduces the chattering phenomenon. Moreover, the obtained results prove the robustness of the proposed control law against variations in load resistance and input voltage in the studied converter.

• KSTLE International Journal
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• 제9권1_2호
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• pp.36-38
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• 2008

The electrical and rheological behavior of the hollow polyaniline glutarate suspension in silicone oil was investigated. Hollow polyaniline glutarate suspension showed a typical ER response (Bingham flow behavior) under a DC electric field. The shear stress for the suspension exhibited the dependence with a factor equals to 0.95 power on the electric field. The experimental results for the hollow polyaniline glutarate suspension behaved as an ER fluid.

• KEPCO Journal on Electric Power and Energy
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• 제5권4호
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• pp.249-256
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• 2019

국내에 향후 건설 예정인 도체귀로형 HVDC ±500 kV Double Bipole 가공송전선로의 최적선로 형상을 설계하고 송전선로에서 발생되는 전기환경장해를 검증하기 위해 실증시험장을 구축하여 1년간 전기환경장해 평가시험을 수행하였다. 또한, HVDC Double Bipole 실선로에서 인체의 지표면 전계인지도 평가시험을 통해 HVDC 실규모 실증선로 직하에서 인체가 직류 전계를 감지하는 임계값을 조사하여 HVDC ±500 kV Double Bipole 가공송전선로의 직류전계 설계기준안의 타당성을 검증하였다. HVDC ±500 kV Double Bipole 시험선로의 극형상은 전기환경장해와 운영관점에서 동일한 극성을 대각으로 배치하였으며, 국내 가공송전선로의 전기환경장해의 사회적인 수용성을 고려하여 선로에서 코로나방전이 거의 발생되지 않도록 소도체 방식은 6 도체를 선정하였다. 도체귀로형 HVDC ±500 kV Double Bipole 가공송전선로 방식인 Cardinal×6B를 적용한 실증시험결과, 선로 도체에서 코로나 방전이 거의 발생되지 않았으며, 따라서 지표면 전계와 이온전류밀도는 모두 국내 가공송전선로 설계 기준값을 만족하였다. 또한 선로직하에서 피조사자들에 대한 전계 인지도 평가결과, 피조사자들의 70%는 23 kV/m에 노출되어도 직류전계를 인지하지 못하는 결과를 나타냈다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.503-504
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• 2011

주파수가 다른 계통을 연계하거나, 장거리 선로 운전시 손실이 낮은 HVDC 송전은 환경문제로 인한 민원으로 새로운 선로건설을 위한 부지확보가 전 세계적으로 어려운 실정이다. 이 문제를 해결할 수 있는 방안으로 기존의 AC선로에 DC를 적용하여 동일철탑에 AC와 DC 선로를 같이 설치하는 하이브리드(Hybird) 선로가 제시되었다. 그러나 AC와 DC가 공존한 상태에서의 전기환경기준이 제시되지 못하고 있는 실정이다. 따라서 본 논문에서는 국내에서 운용중인 345kV 2회선 철탑에 DC선로를 적용한 하이브리드 선로의 축소모델을 제작하였고, DC선로의 도체 구성별 하이브리드 선로의 이온류 특성을 시험하였다.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.176-187
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• 2015

DC bias will cause abnormal vibration of transformers. Aiming at such a problem, transformer vibration affected by DC bias has been studied combined with transformer core and winding vibration mechanism use multi-physical field simulation software COMSOL in this paper. Furthermore the coupling model of electromagnetic-structural force field has been established, and the variation pattern of inner flux density, distribution of mechanical stress, tension and displacement were analyzed based on the coupling model. Finally, an experiment platform has been built up which was employed to verify the correctness of model.

• 지질공학
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• 제30권4호
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• pp.423-433
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• 2020

Direct current (DC) electric fields have been used for electro-osmotic dewatering. Under DC conditions, however, the electrical contact resistance between the electrode and the dewatering material increases considerably during the process of dewatering. Such a circumstance hinders the continuation of effective electro-osmotic dewatering. To reduce this hindrance, an applied pulse electric field with periodic reversals of the electrode polarity should improve electro-osmotic dewatering. In this study, electro-osmotic dewatering under pulse conditions was experimentally investigated for electrode polarity reversals. During the dewatering process, the pulse electric field was able to reduce the hindrance caused by the DC, resulting in an increased final dewatered amount relative to that under a DC electric field. For a constant applied voltage, the reversed polarity condition, under which the electric current passing through the material was almost unchanged with time, yielded the maximum final dewatered amount. This technique can be used to enhance drainage from a water storage facility during a period of extreme drought and the seawater desalination plants using reverse osmosis in drought stricken coastal regions.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.427-430
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• 2002

This paper has been studied a new geoelectric survey and instrunmentation using Low Frequency Electric Field .sensing Antenna. “Low Frequency Electric Field Sensing” is a technology in new method of survey to use array type antenna, the power of operation in antenna is using AC or DC pulse instead of DC current. The architecture of system embodied transceiver system using a microprocessor(PIC) of Microcllip Technology Inc. An array antenna design and il control transmission of antenna to use CDMA in this system. It is using array type antenna for the earth、earth's crust to survey explain from theory and experience.

• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.720-723
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• 2005

We studied the quantitativity of the image sticking which is occured by the resicual DC in the fringe-electric field switching (FFS) mode. Actually, in the FFS mode driven by the strong fringe electric field, the asymmetric residual DC was formed in the bottom substrate. It made the impurity ion stick to the alignment layer such as polyimde layer. Thus, the differnece of the luminance existes after the stress check pattern is applied to the panel so that we can see the image sticking. This image sticking decreases as the residual DC value between specific patterns decreases. Therefore, it is necessary to control the residual DC for the FFS mode with the high image quality. It is possible to eliminate the image stiking when the extra pixel voltage is applied through the circuit tunning for reducing the difference of residual DC accroding to the panel position.

• 대한전자공학회논문지SD
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• 제47권6호
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• pp.1-6
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• 2010

본 논문에서는 고출력 고이득 특성을 갖는 고전자이동도 트랜지스터 (high-electron mobility transistor, HEMT)를 구현하기 위하여 계단형 구조의 게이트 전극을 갖는 AlGaN/GaN HEMT를 제안하였고, 소자의 DC 특성의 향상 가능성을 확인하기 위하여 단일 게이트 전극을 갖는 HEMT 및 field-plate 구조의 게이트 전극을 갖는 HEMT 소자와의 특성을 비교 분석하였다. 상용 시뮬레이터를 통해 시뮬레이션 결과, 본 연구에서 제안한 계단형 구조의 게이트 전극을 갖는 AlGaN/GaN HEMT는 드레인 전압의 인가 시, 소자의 내부에서 발생하는 전계가 단일 게이트 전극을 갖는 HEMT에 비해 약 70% 정도 감소하는 특성을 갖는 것을 확인하였고, 전달이득 (transconductance, $g_m$) 특성 역시 단일 게이트 전극구조의 HEMT나 field-plate 구조를 삽입한 HEMT에 비해 약 11.4% 정도 향상된 우수한 DC 특성을 갖는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.462-464
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• 1995

In this paper, experiments were carried out to study the decrease of NOx in simulated flue gases (initial concentration of NO 1000, 750, 400 ppm, : $N_2$ balance gas). Characteristics of NOx reduction are measured and analysed in corona discharge of multi needles to plane electrode structure and magnetic field. The best characteristics of NO reduction is measured when electric and magnetic field were supplied to reactor, at same time. Consumption power applied electric and magnetic field were higher than that of discharge applied only electric field.