• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1967-1977
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• 2014

In this paper, for the development of a safe and reliable DC home appliance suitable for DC home power supply system, we classified a number of inherent problems with help of the comparative analysis of existing AC and new DC home appliance. Several new technical problems of DC home appliances are mainly linked to the DC transient state. Among them, this paper concentrates on start-up inrush current problem, uni-polarity problem, and heavy DC load control problem. And to address these problems, we herein present an implementation of robust safety circuits for DC home appliances. Specifically, we investigate several multi-circuit countermeasures and select the best among them through comparative evaluation, based on theoretical, simulational, and experimental results.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.51-57
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• 2012

This paper provides a safety guideline for DC supplied home appliances through the comparative analysis of existing safety guideline for AC supplied home appliances. For this purpose, a predictive DC home appliance model is suggested and in special international safety standards of AC appliances are also analyzed. Moreover, a DC distribution system is built to verify the validity of the proposed safety guideline. The detailed analyzing process is explained with help of informative experimental results.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.356-359
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• 2001

In this paper, the new control algorithm is proposed that compensates instantaneously the active and reactive components of the input currents by the synchronous d,q axis conversion of a single-phase current in controlling the single-phase AC/DC parallel converters for a high speed train. The leakage inductance of a transformer was used as a boost inductance and the ripple of a transformer's primary current was reduced considerably by the parallel operation of the two converters with a proper switching phase-shift. The stable and fast control response characteristic is certificated by a simulation.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.484-488
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• 2001

The grid voltage of commercial utility power source hi Japan and USA is 100rms, but in China and European countries, it is 200rms. In recent years, In Japan 200Vrms out putted single phase three wire system begins to be used for high power applications. In 100Vrms utility AC power applications and systems, an active voltage clamped quasi-resonant Inverter circuit topology using IGBTs has been effectively used so far for the consumer microwave oven. In this paper, presented is a half bridge type voltage-clamped high-frequency Inverter type AC-DC converter using which is designed for consumer magnetron drive used as the consumer microwave oven in 200V utility AC power system. This zero voltage soft switching Inverter can use the same power rated switching semiconductor devices and three-winding high frequency transformer as those of the active voltage clamped quasi-resonant Inverter using the IGBTs that has already been used for 100V utility AC power source. The operating performances of the voltage source single ended push pull type Inverter are evaluated and discussed for consumer microwave oven. The harmonic line current components In the utility AC power side of the AC-DC power converter operating at ZVS­PWM strategy reduced and improved on the basis of sine wave like pulse frequency modulation and sine wave like pulse width modulation for the utility AC voltage source.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.461-462
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• 2007

DC Arc is an electric discharge which is occurred in two oppolsite electrode when system operating with DC current appliance. In this paper, DC arc detection system is designed for the display of DC arc fault current which is occurred in the local electric network with DC Power. This DC arc is one of the main causes of electric fire of dc system. Arc fault in electrical network has the characteristics of low current, high impedance and low frequency. DC Arc current detection device is designed for the display of arc fault current which has the modified arc characteristics.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1037-1039
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• 2002

가전산업과 연계하여 유도가열 기술을 응용한 대표적인 시스템으로 IH압력밥솥을 예로 들 수 있다. 유도가열 코일에서 고주파 자속의 의해 발생된 와전류가 결합된 밥솥을 가열하기 때문에 유도가열 코일에는 고주파 손실을 줄이기 위해 Litz wire가 사용된다 이에 본 논문은 특히 IH압력밥솥에 사용되는 Litz wire를 선정하는 데 있어 중요한 요소가 되는 소선경, 가닥수별 AC DC 저항 및 손실계산 그리고 Cost 예측 방법을 제안한다.

• The KSFM Journal of Fluid Machinery
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• v.18 no.3
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• pp.33-37
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• 2015

A numerical study on the IPM/Bridge Diode cooling and coil cooling has been performed. Results are presented as plots of thermal resistance, temperature drop and RPM-ratio. CFD analysis for conventional cooling system has been performed as a reference case. As the RPM-Ratio was increased, heatsink thermal resistance and coil temperature were decreased. IPM/Bridge Diode thermal resistance and temperature of the coil is tended to be trade-off. The temperature of coil closest to the AC-motor fan showed the most significant change in accordance with duct design. The temperature of coil located at the top of DC-motor fan showed the most significant variation as the cooling air passes the heatsink fin area.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.77-85
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• 2009

With the advent of power semiconductor switching devices, power electronics relating to high frequency electromagnetic eddy current based induction heating technology have become more suitable and acceptable. This paper presents high-frequency induction heating cooking appliance circuit based on the zero current switching-PWM single ended push-pull(ZCS-PWM SEPP) resonant inverter added AC-DC converter. This inverter uses pulse-width-modulation(PWM) control method with active auxiliary quasi-resonant lossless inductor snubbers and a switched capacitor. To improved the transient performance, the PI controller is applied for this system. For the systematic parameter optimization of the PI controller, the gradient-based optimization algorithm is applied. The performance of optimized parameters is evaluated using simulation and experimental test. These results show that the proposed systematic optimal tuning method improve the transient performances of this system.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.3
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• pp.193-197
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• 2012

This paper focuses on identifying which appliance is currently operating by analyzing electrical load signature for home energy monitoring system. The identification framework is comprised of three steps. Firstly, specific appliance features, or signatures, were chosen, which are DC (Duty Cycle), SO (Slope of On-state), VO (Variance of On-state), and ZC (Zero Crossing) by reviewing observations of appliances from 13 houses for 3 days. Five appliances of electrical rice cooker, kimchi-refrigerator, PC, refrigerator, and TV were chosen for the identification with high penetration rate and total operation-time in Korea. Secondly, K-NN and Naive Bayesian classifiers, which are commonly used in many applications, are employed to estimate from which appliance the signatures are obtained. Lastly, one of candidates is selected as final identification result by majority voting. The proposed identification frame showed identification success rate of 94.23%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.76-76
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• 2008

갈륨-질화물(GaN) 기반의 고속전자이동도 트랜지스터(high electron mobility transistor, HEMT)는 최근 마이크로파 또는 밀리미터파 등의 고주파 대역의 통신시스템에 널리 사용되는 전자소자이자, 차세대 고주파용 전력 소자로 각광받고 있다. AlGaN/GaN HEMT에서 AlGaN층과 GaN층의 이종접합 구조(heterostructure)는 두 물질 간의 큰 전도대의 불연속성으로 인해 발생하는 이차원 전자가스(two-dimensional electron gas, 2DEG) 채널을 이용하여 높은 전자이동도, 높은 항복전압 및 우수한 고출력 특성을 얻는 것이 가능하다. 그러나 이린 이론적인 우수한 특성에도 불구하고 실제 AlGaN/GaN HEMT 소자에서는 AlGaN 표면과 AlGaN과 GaN 층 사이 접합면, AlGaN과 GaN 벌크층에 존재하는 트랩의 영향으로 이론보다 낮은 DC 출력 특성을 갖는다. 본 논문에서는 표면, 접합면, 벌크 층에 존재하는 트랩들을 각각의 존재 유무에 따라 시뮬레이션 함으로써 각각의 트랩이 DC 특성에 미치는 영향에 대해서 알아본다. 또한 소스와 게이트, 드레인과 게이트간의 거리에 따라 표면 트랩에 따른 영향과 AlGaN층과 GaN 층의 두께를 변화시켜가면서 각 층의 두께에 따라 벌크 트랩이 DC 특성에 미치는 영향을 알아보았다. 본 논문에서 트랩에 따른 특성의 파악을 위해서 $ATLAS^{TM}$를 이용하여 전산모사 하였다.