• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.3
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• pp.181-190
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• 2019

Active power decoupling circuits have emerged to eliminate the inherent second-order ripple power in a single-phase power conversion system. This study proposes a design method to determine the optimal capacitance for active power decoupling circuits to achieve high power density. Minimum capacitance is derived by analyzing ripple power in a passive power decoupling circuit, a buck-type circuit, and a capacitor-split-type circuit. Double-frequency ripple power decoupling capabilities are also analyzed in three decoupling circuits under a 3.3 kW load condition for a battery charger application. To verify the proposed design method, the performance of the three decoupling circuits with the derived minimum capacitance is compared and analyzed through the results of MATLAB -Simulink and hardware-in-the-loop simulations.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.31-33
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• 2020

본 논문은 고효율 11kW급 양방향 탑재형 충전기에 대한 연구결과를 발표한다. 토폴로지로는 3상 2-레벨 인버터와 CLLLC 공진형 컨버터를 적용하였으며, 모든 전력반도체 소자는 SiC-MOSFET를 적용하였다. CLLLC 공진형 컨버터의 고효율 달성을 위해, 배터리 전압에 따라 DC 링크 전압 가변 알고리즘을 적용하였으며 양방향 동작시 정류단이 동기 정류기로 동작하도록 설계하였다. 인버터 스위칭 주파수 20kHz, CLLLC 공진형 컨버터 스위칭 주파수 80~300kHz, 배터리 전압 213~413V, 계통 전압 380V/60Hz 사양으로 프로토타입을 설계/제작하였으며 순방향 전력전달 최대 효율 95.8%이상, 역방향 전력전달시 최대효율 95.1%이상의 결과를 달성하였다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.310-311
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• 2020

본 논문에서는 단일 스테이지 양방향 배터리 충방전용 센터-탭 액티브 클램프 포워드 DC-DC 컨버터를 제안한다. 포워드 컨버터의 액티브 스위치의 전압 스트레스를 줄이려면 보조 스위치와 클램프 커패시터는 변압기 누설에 저장된 에너지를 재활용하여 동작하며 양방향으로 동작하는 센터-탭 포워드 파형을 분석하였다. 또한 단일 스테이지 양방향 컨버터로서 여러개의 모듈을 병렬로 연결하여 확장시킬 수 있는 점을 검토하였다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.457-458
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• 2020

본 논문은 저전압 직류배전 (LVDC)이 도입된 공장 및 물류센터 등 에서 다수의 전동 지게차를 운용할 때, 효과적으로 충전할 수 있는 지게차 배터리 충전기를 제안하였다. 제안하는 충전기는 SiC 반도체 및 의도적으로 비대칭으로 설계한 공진 인덕터를 사용한 두 개의 위상천이 풀브릿지 컨버터로 구성된다. 이를 통하여 최대 200A급 고속 충전 및 다종의 배터리 규격 (48V, 80V) 대응과 함께 고효율, 고전력밀도를 달성 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.207-209
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• 2015

Recently, with the economy and the information communication technology developed, the smartphone market grows continuously. The market outlook on the wireless rechargeable technology grows rapidly so that the market size is increased about six times bigger than that of the last year, and it will grow about 18 billion dollars in 2014. Because of that, as the interest on this area out focused, many kinds of technology and new product are being exploited in this field. Participants of this study were 76 mobile users in Gyeongnam and Jeonbuk province in accordance with convenience sampling. Most of the respondents about 88 percent, the wireless charger may be answered to be able to explain what it is. Also, about 70 percent of the respondents, is time to replace the future of smart phone, answered by selecting a product in consideration of the wireless charging. Based on these findings, several theoretical and practical implications were suggested.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.297-303
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• 2016

This paper introduces auxiliary power supply systems (APS) for railroad applications and proposes a new power conversion structure for highly-efficient and lightweight APS systems. The proposed structure focuses on an improvement of the power density in APS. It eliminates unnecessary power conversion stages in the conventional APS structure by modulating the dc/dc converter circuit and the structure of the system. The dc/dc converter circuit used in the proposed structure is based on a multi-level half-bridge converter, a widely used topology in railroad APS applications; a flying capacitor is newly added to the conventional circuit. The added capacitor is used not only to enhance the soft switching condition of the switches, but also so that the new pantograph will have a side voltage source of a battery charger in the APS structure. Since the battery charger uses the pantograph side voltage source in the proposed structure, rather than using the output of the main dc/dc converter in the conventional structure, the size and efficiency of the main dc/dc converter are reduced and increased, respectively. To verify the effectiveness of the proposed structure, simulation results will be presented with metropolitan transit APS specifications.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.6
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• pp.845-856
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• 2014

This study focused on the production and usability evaluation of smart outdoor jackets that are designed to provide convenience to middle-aged people by embedding devices for lighting and location tracing. The results were as follows. 1. Jacket power supplier was a assembled system composed of battery, charger, controller and switch. A solar cell was attached on the upper arm, and a wire type EL on the center line of a raglan sleeve along with a GPS on the left sleeve with a transparent vinyl pocket. The total weight of the jacket embedded with devices was 385-520g. 2. Operation of function, activity, acceptability, safety, convenience for device use, appearance, practical maintenance were selected based on an analysis of evaluation criteria of previous smart wear research. Criteria were narrowed to three major categories of satisfaction, appearance and maintenance. 3. Use satisfaction criterion consisted of wearable device functionality and physical, psychological use convenience. The evaluation indicated actual functionality. EL functions were especially effective and necessary. Convenience of use showed that a smart jacket was thought to be safe and the size was moderate regardless of age and gender. Outer appearance was satisfactory and respondents praised the color. The practical maintenance evaluation indicated that there was no challenge in doing the laundry since the solar battery and GPS were detachable. The practical use of smart outdoor jackets confirmed by fabric that was washable and dried quickly.

• Journal of Energy Engineering
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• v.2 no.1
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• pp.104-113
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• 1993

Due to steady increase of electric power demand and decrease of load factor, the economic and reasonable operation of electric power system is necessary. Because of this reason, dispersed battery energy storage system(BESS) with fast response is receiving attractive attention. With these considerations, 20 kVA BESS is designed and tested to investigate the possibility of BESS application to power system. This paper describes the design specifications of simulator and test results. BESS is composed of batteries, conversion equipments, interconnecting equipments to power system, and control parts of the system. The inverter of BESS can carry out two functions as charger and discharger. Also, it can operate as a VAR compensator by four quadrant operation. Since this system is designed as a simulator of MW system, the conceptual design of MW system is possible by using the test result of test system The study of BESS is preliminary stage for the future MW class BESS.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.120-128
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• 2015

In this paper, Residential roof top photovoltaic system with 9.9 kW design is proposed. The system composed of 200 Watts solar array 33 panels connecting in series 10 strings and parallels 3 strings which have maximum voltage and current are 350 V and 23.8 A. The 10 kW sinusoidal grid-connected inverter with window voltage about 270-350 is selected to convert and transfer DC Power to AC Power at PCC (Point of Common Coupling) of power system following to utility standard. However the impact of fluctuation and uncertainty of weather condition of PV may decrease the voltage stability and voltage collapse of power system. In order to solve this problem the energy storage such 120 V 1200 Ah battery bank and 30 kVAR capacitor are designed for voltage stability control. The other expensed for installing the system such battery charger, cable, accessories and maintenance cost are concerned. The economic analysis by using investment from money loan with interest about 7% and use own money which loss income of deposit about 3% are calculated as 671,844 and 547,044 for PV system with energy storage and non energy storage respectively. The solar energy from PV is about 101,616 Bath per year which evaluated by using the value of $5kWh/m^2/day$ from average peak sun hour (PSH) of the Thailand and 6.96 Bath/kWh of Feed in Tariff Incentive. The payback periods of four scenarios are proposed follow as i) PV system with energy storage and use loan money is 15 years ii) PV system with no energy storage and use loan money is 10 years iii) PV system with energy storage and use deposit money is 9 years iv) PV system with energy storage and use deposit money is 7 years. In addition, the other scenarios of economic analysis such no FIT support and other type of economic analysis such NPV and IRR are proposed in this paper.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.920-926
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• 2011

In this paper, a solar power emotional LED lightening street lamps with multi control sun tracker is presented. The proposed system has a multiple control sun tracking function and high quality emotional LED lamps. The system is designed to absorb maximum sun lights by temperature sensor and humidity sensor of control circuits. A battery charge-discharge controller is developed for high efficient usage of battery charger for utilization of new and renewal energy. An interface circuit for remote monitoring and controlling is included in the developed system. The proposed multi tracking solar power emotional LED street lamps is better than conventional systems in aspect of tracking operation and energy efficiency, and expected to be a leading model for next generation solar power street lamp system, because it is a new technology combining sun tracking solar power system and emotional lightening system.