• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.391-393
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• 2008

A modified boost converter with magnetic coupling is presented to reduce the reverse recovery loss while maintaining low conduction loss of the rectifiers. By utilizing a coupled inductor and a set of diodes, the current passing the boost rectifier is transferred to an auxiliary loop before turn-off, allowing low di/dt for reduced recovery loss. Moreover, the boost inductor is brought inside the bridge rectifier to reduce conduction loss by decreasing the number of conducting diodes during switch turn-off. Experimental results of a 500W prototype are provided to verify the increase in efficiency and validity of the proposed converter.

• 한국초전도ㆍ저온공학회논문지
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• 제5권2호
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• pp.58-65
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• 2003

The high temperature superconductivity(HTS) cable must be cooled below the nitrogen liquefaction temperature to applicate the cable in power generation and transmi-ssion system under the superconducting state. To obtain superconducting state. a reliable cryocooler system is required. Structural and thermal design have been performed to design cryocooler system operated with reverse Brayton cycle using gas neon as refrigerant. This cryocooler system consists of compressor. recuperator. coldbox. control valves and has 1 kW cooling capacity. Heat loss calculation was conducted for the given cryocooler system by considering the conduction and radiation through the multi-layer insulation(MLI) and high vacuum. The results can be summarized as: conduction heat loss is 7 W in valves and access port and radiation heat loss is 18 W through the surface of cryocooler. The full design specifications were discussed and the results were applied to construct in house HTS cable cooling system.

• Journal of Power Electronics
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• 제16권5호
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• pp.1689-1697
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• 2016

Continuous conduction mode (CCM) boost converters are commonly used in home appliances and various industries because of their simple topology and low input current ripples. However, these converters suffer from several disadvantages, such as hard switching of the active switch and reverse recovery problems of the output diode. These disadvantages increase voltage stresses across the switch and output diode and thus contribute to switching losses and electromagnetic interference. A new topology is presented in this work to improve the switching characteristics of CCM boost converters. Zero-current turn-on and zero-voltage turn-off are achieved for the active switches. The reverse-recovery current is reduced by soft turning-off the output diode. In addition, an input current sensorless control is applied to the proposed topology by pre-calculating the duty cycles of the active switches. Power factor correction is thus achieved with less effort than that required in the traditional method. Simulation and experimental results verify the soft-switching characteristics of the proposed topology and the effectiveness of the proposed input current sensorless control.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.359-359
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• 2010

IGBT(Insulated Gate Bipolar Transistor) 란 MOS(Metal Oxide Silicon) 와 Bipolar 기술의 결정체로 낮은 순방향 손실(Low Saturation)과 빠른 Speed를 특징으로 기존의 Thyristor, BJT, MOSFET 등으로 실현 불가능한 분양의 응용처를 대상으로 적용이 확대 되고 있고, 300V 이상의 High Power Application 영역에서 널리 사용되고 있는 고효율, 고속의 전력 시스템에 있어서 필수적으로 이용되는 Power Device이다. IGBT는 출력 특성 면에서 Bipolar Transistor 이상의 전류 능력을 가지고 있고 입력 특성 면에서 MOSFET과 같이 Gate 구동 특성을 갖기 때문에 High Switching, High Power에 적용이 가능한 소자이다. 반면에, Conventional IGBT는 MOSFET과 달리 IGBT 내부에 Anti-Parallel Diode가 없기 때문에 Inductive Load Application 적용시에는 별도의 Free Wheeling Diode가 필요하다. 그래서, 본 논문에서 별도의 Anti-Parallel Diode의 추가 없이도 Inductive Load Application에 적용 가능한 RC IGBT를 적용하여 600V/15A급 Three Phase Inverter Module을 제안 하고자 한다.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.176-180
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• 2003

To obtain superconducting state, a reliable cryocooler system is required. Structural and thermal design have been performed to design cryocooler system operated with reverse Brayton cycle using gas neon as refrigerant. This cryocooler system consists of compressor recuperator, coldbox, control valves and has 1 ㎾ cooling capacity. Heat loss calculation was conducted for the given cryocooler system by considering the conduction and radiation through the multi-layer insulation (MLI) and high vacuum. The results can be summarized as; conduction heat loss is 7 W in valves and access port and radiation heat loss is 18 W through the surface of cryocooler. The full design specifications were discussed.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2310-2318
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• 2018

Critical conduction mode (CRM) operation is more efficient than continuous conduction mode (CCM) operation at low power levels because of the valley switching of switches and elimination of the reverse recovery losses of boost diodes. When using a sensorless digital control method, an error occurs between the actual and the estimated current. Because of the error, it operates as CCM or discontinuous conduction mode (DCM) during CRM operation and also has an adverse effect on THD of input current. In this paper, a current sensorless technique is presented in an inverter system using a bridgeless boosted power factor correction converter, and a compensation method is proposed to reduce CRM calculation error. The validity of the proposed method is verified by simulation and experiment.

• E2M - 전기 전자와 첨단 소재
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• 제10권5호
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• pp.447-452
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• 1997

Effects of metal impurities in insulation of distribution cables on electrical conduction of distribution cables was investigated. Samples of Al, Cu, Fe are fabricated as metallic impurities, and measured electrical conductivity in the voltage range of 0~10 KV. Temperature dependent effect of hysteresis curves and the relationship between forward and reverse current due to impurity content are discussed.

• Journal of Medicine and Life Science
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• 제21권3호
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• pp.112-116
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• 2024

Complete left bundle branch block (CLBBB) is a significant cardiac conduction abnormality often associated with dilated cardiomyopathy (DCM). This case report highlights the improvement in CLBBB and symptom relief through reverse cardiac remodeling in a patient diagnosed with DCM following an optimized heart failure treatment regimen consisting of an angiotensin-converting enzyme inhibitor, beta-blocker, and mineralocorticoid receptor antagonist. This case highlights the potential of electrical remodeling and conduction system improvement in patients with DCM receiving optimized medical therapy.

• ETRI Journal
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• 제35권4호
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• pp.603-609
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• 2013

In this paper, we present a 600-V reverse conducting insulated gate bipolar transistor (RC-IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC-IGBT uses the deep reactive-ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC-IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.

• 조명전기설비학회논문지
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• 제29권1호
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• pp.80-85
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• 2015

In the issues of interleaved topology which have been in limelight as high power converter, various soft-switching methods are studied to reduce switching losses in high power application. The interleaved ZCT converter has an additional filter inductor to reduce losses of diodes during reverse recovery process. However, additional current conduction modes are occurred by the inductor, we need to analyze switching losses with inductor values on each mode. In this paper, current conduction modes and boundary conditions of interleaved ZCT converter are analyzed. In the conclusion, the minimum of switching losses in converter operation modes is analyzed by calculating switching losses.