• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.103-105
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• 2002

Instantaneous following PWM control technique is pulsed nonlinear dynamic control method. This new control technique using analog integrator is proposed to control the duty ratio D of Cuk converter. In this control method, the duty ratio of a switch is exactly equal to or proportional to the control reference in the steady state or in a transient. Proposed control method compensates power source perturbation in one switching cycle, and the average value of the dynamic reference in one switching cycle. There is no steady state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with Cuk converter have demonstrated the robustness of the control method and verified theoretical prediction. The control method is very general and applicable to all type PWM.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.73.2-73.2
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• 2010

휴대용 전자기기들의 소비전력 증가에 따라 2차전지에 비해 에너지 밀도가 높은 연료전지를 이용한 충전기의 필요성이 부각되고 있다. 대다수의 충전기는 On-Grid 방식으로 벅타입 컨버터를 이용한 감압 방식이었으나, 연료전지를 이용할 경우 승압식 컨버터를 통한 배터리의 충전이 요구된다. 또한 배터리는 일반 저항부하와 달리 큰 커패시턴스 성분을 가지고 있기 때문에 컨버터의 출력단에 인덕터가 없는 경우 큰 출력 리플전류를 유도하게 되어 시스템의 효율과 배터리의 수명에 좋지 않은 영향을 끼치게 된다. 또한 이를 해결하기 위해 절연형 감압 컨버터를 사용하는 경우 변압기 사용에 의한 부피 증가와 부가 소자의 사용에 따른 가격 상승을 피하기 어렵다. Cuk 컨버터는 주스위치의 ON/OFF 동작에 관계없이 출력으로 에너지가 항상 전달되며, 이상적으로 리플이 거의 존재하지 않아 충전용으로 적합하다. 또한, 승압 및 감압이 자유롭기 때문에 배터리의 정격전압에 상관없는 범용 충전기의 설계도 가능하다. 따라서 본 논문에서는 Cuk 컨버터를 이용하여 배터리 충전기를 설계하고, 그의 상태공간 모델링, 주파수 특성 해석 및 제어기 설계에 대해 기술한다. 제안된 제어 방식은 소형 연료전지 스택을 이용하여 실제 배터리를 대상으로 한 정전류 및 정전압 제어를 실행하여 그 성능 및 안정성을 검증한다.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.916-924
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• 2015

Electromagnetic Interference (EMI) is a system to system or environment to system phenomenon. The literature survey proved that the Randomized Pulse Width Modulation (RPWM) technique is a promising technique to reduce EMI. A new Constant Trailing Edge, Randomized Pulse Width Modulation (CTERPWM) technique is proposed in this paper. The effect of the proposed RPWM technique for mitigation of conducted-EMI on Cuk converter operating in Continuous Conduction Mode (CCM) is simulated and tested. In this paper, the analytical expressions for the Power Spectral Density (PSD) are derived for the proposed RPWM technique and are validated by experimental measurements. The effectiveness of the proposed RPWM technique on the mitigation of conducted-EMI is verified comparing simulation and experimental results and it is identified that both the results are almost similar with allowable experimental deviations. The comparative investigation proves that the proposed RPWM technique can mitigate and spread the dominant peaks of conducted-EMI over the complete spectrum for the Cuk converter. Based on the investigation the CTERPWM technique is recommended for adoption.

• Current Applied Physics
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• v.18 no.11
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• pp.1190-1195
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• 2018

By employing soft X-ray magnetic circular dichroism (XMCD), soft X-ray absorption spectroscopy (XAS), and photoemission spectroscopy (PES), we have investigated the electronic structure of the candidate zero-moment half-metallic $Mn_3Ga$. We have studied the ball-milled and annealed $Mn_3Ga$ powder samples that exhibit nearly zero magnetization. Mn 2p XAS revealed that Mn ions in $Mn_3Ga$ are nearly divalent for both of the Mn ions having the locally octahedral symmetry and those having the locally tetrahedral symmetry. The measured Mn 2p XMCD spectrum of $Mn_3Ga$ is very similar to that of ferrimagnetic $MnFe_2O_4$ having divalent Mn ions. The sum-rule analysis of the Mn 2p XMCD spectrum shows that both the spin and orbital magnetic moments of Mn ions in $Mn_3Ga$ are negligibly small, in agreement with the nearly compensated-ferrimagnetic ground state of $Mn_3Ga$. The valence-band PES spectrum of $Mn_3Ga$ agrees well with the calculated density of states, supporting the half-metallic electronic structure of $Mn_3Ga$.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.408-409
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• 2010

본 논문에서는 소형 PEM(Proton Exchange Membrane) 연료전지를 이용하는 충전기에 관해 서술한다. 기존에 개발된 대부분의 충전기는 On-Grid 방식으로 벅타입 컨버터를 이용한 감압 충전방식을 사용하였으나, 연료전지를 이용할 경우 승압식 컨버터를 통해 배터리를 충전하여야 한다. 그러나 승압형 컨버터의 출력단에 인덕터가 없는 경우 큰 리플전류를 유도하게 되며, 이는 시스템의 효율 및 배터리의 수명에 좋지 않은 영향을 끼치게 된다. 본 논문에서는 Cuk 컨버터를 이용하는 충전용 전력변환기의 제어방법에 관해 제안하고 그 타당성을 검증하였다.

• Journal of Power Electronics
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• v.19 no.4
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• pp.894-906
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• 2019

In this paper, a DC-DC converter is proposed based on the Cuk converter. The proposed converter has high efficiency and it can be used in multilevel DC-DC converters. A reduction of the inductors size in comparison to Cuk converter and a reduction in the inductors resistance negative effects on efficiency are the important points of the proposed converter. Its voltage ripple is reduced when compared to other converters. Its output voltage has a high quality and does not contain spikes. A theoretical analysis demonstrates the positive points of the proposed converter. The design and analysis of the converter are done in continues conduction mode (CCM). Experiments confirm the obtained theoretical equations. The proposed converter voltage gain is similar to that of a conventional Boost converter. As a result, they are compared. The comparison illustrates the advantages of the proposed converter and its higher quality. Furthermore, a prototype of the proposed converter and its combination with a 2x multiplier are built in the lab. Experimental results validate the analysis. In addition, they are in good agreements with each other.

• Journal of Power Electronics
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• v.8 no.1
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• pp.51-59
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• 2008

This paper addresses several issues concerning the analysis, design, modeling, simulation and development of single-phase, single-switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis and design is presented for single-switch topologies, namely forward buck, flyback, Cuk, Sepic and Zeta buck-boost converters, with high frequency isolation for discontinuous conduction modes (DCM) of operation. With an awareness of modem design trends towards improved performance, these switching converters are designed for low power rating and low output voltage, typically 20.25W with 13.5V in DCM operation. Laboratory prototypes of the proposed single-switch converters in DCM operation are developed and test results are presented to validate the proposed design and developed model of the system.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.151-154
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• 1988

Quantum converters, a subset of resonant converters operating with optimal conditions are modeled. It is shown that series resonant converter(SRC) can be modeled as buck/boost converter with an equivalent inductor and parallel resonant converter(PRC) can be modeled as Cuk converter, with an equivalent capacitor. Also new resonant circuits with boost, buck-boost and Cuk converter characteristics are proposed. From these models, the quantum converters can be designed to be controlled with closed loop feedback, having many advantages such as low device switching stress, reliable high frequency operation and low EMI.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.7089-7095
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• 2015

Clinical evidence shows that dual inhibition of kinases as well angiogenesis provides ideal therapeutic option in the treatment of medullary thyroid carcinoma (MTC) than inhibiting either of these with the events separately. Although treatment with dual inhibitors has shown good clinical responses in patients with MTC, it has been associated with serious side effects. Some inhibitors are active agents for both angiogenesis or kinase activity. Owing to narrow therapeutic window of established inhibitors, the present study aims to identify high affinity dual inhibitors targeting RET and VEGFR2 respectively for kinase and angiogenesis activity. Established inhibitors like Vandetanib, Cabozantinib, Motesanib, PP121, RAF265 and Sunitinib served as query parent compounds for identification of structurally similar compounds by Tanimoto-based similarity searching with a threshold of 95% against the PubChem database. All the parent inhibitors and respective similar compounds were docked against RET and VEGFR2 in order to retrieve high affinity compounds with these two proteins. AGN-PC-0CUK9P PubCID: 59320403 a compound related to PPI21 showed almost equal affinity for RET and VEGFR2 and unlike other screened compounds with no apparent bias for either of the receptors. Further, AGNPC- 0CUK9P demonstrated appreciable interaction with both RET and VEGFR2 and superior kinase activity in addition to showed optimal ADMET properties and pharmacophore features. From our in silico investigation we suggest AGN-PC-0CUK9P as a superior dual inhibitor targeting RET and VEGFR2 with high efficacy which should be proposed for pharmacodynamic and pharmacokinetic studies for improved treatment of MTC.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.355-358
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• 2004

Currently, to overcome the limit of a 14V power supply system and to enhance the stability of this system high and to make the fuel efficiency better, a research development of a 42V power supply system is actively the progress. As an intermediate step to change into an unity power supply system, a 42V/14V dual power supply system uses a DC/DC Converter as one of structure elements. Considering the main electric power sources in the next generation of the car is a 42V system a 14V power supply system has advantages as follows : In be managed efficiently and to increase the redundancy at start, to jump start with any vehicles, etc. We need the introduction of a hi-directional converter that can flow the energy each other in a dual 42V-l2V system. This paper proposed the ZVS hi-directional CUK DC/DC converter which decrease the weight with the size of the DC/DC Converter and minimize the loss when the switching happen. In this paper, a circuit design method and an action principle of the circuit was proposed. To verify the proposed circuit, a comprehensive evaluation with theoretical analysis, simulation results is presented.