• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.137-142
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• 2021

A Photovoltaic power streetlight is a system that uses solar energy to charge a secondary battery and then uses it for night lighting through a lamp, and can be configured as a standalone or grid-connected type by installing an LED streetlight at the load end. The energy generated through the solar cell module can be charged to the secondary battery through the charge/discharge control device, and then the LED street light can be turned on and off by comparing the power generation voltage and the charging voltage according to the monitoring of solar radiation, or by setting a specific time after sunset or sunrise. Based on these contents, this paper designed and manufactured a simulated solar power streetlight for education using new and renewable energy utilization and storage functions. Using these educational equipment, students can 1) understand the flow of energy change using renewable energy including sunlight as electric energy, 2) understand new and renewable energy, and cultivate basic design and manufacturing application power of related products, 3) The use of new and renewable energy through power conversion and strengthening of practical training and analysis through hardware production can be instilled.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.7
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• pp.118-126
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• 2003

In this study, a battery charge and discharge regulator of modular type is designed as paralleled bi-directional converter that is possible to provide the power without failure not only in the steady state but also in the transient period by the step load variation or the unexpected faults among the converter modules. Each converter module is designed to get stability, performance, reliability, and maintainability and the average current mode method used for controller has the advantages such as noise immunity, fast response, and the real average current signal acquisition. The equivalent model and small signal model for the paralleled battery chargerIdischarger are presented, and also the transfer functions are analyzed for the CCM(Continuous Charge Mode), CDM(Continuous Discharge Mode) and DDM(Discontinuous Discharge Mode). The experiments of the paralleled bi-directional converter are carried out in the step load variation, and in faults of one converter module respectively. And the performance of paralleled bi-directional converter is verified via the experimental results.

• Journal of the Korean Electrochemical Society
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• v.27 no.2
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• pp.55-72
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• 2024

Secondary batteries are used as an essential renewable energy source in our lives, such as electric vehicles and energy storage systems (ESS), as an alternative to fossil fuels due to global warming. However, cases of battery fires and explosions have been reported due to thermal runaway in secondary batteries due to various causes such as overdischarge, high-speed charging and discharging, and external short circuit, and great efforts are being made to find solutions suitable for each cause. In particular, as cases presumed to be caused by the overcharging process have been reported, this review will examine the chemical reactions of secondary batteries that can occur during the overcharging process and discuss risk investigation methods to check and prevent them.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.566-572
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• 2020

In a wireless power transmitter, the characteristics and effects of wireless power transmission between two induction coils are investigated, and a power converter circuit and a battery charger/discharger circuit using wireless power transmission technology are proposed. The advantage of wireless power transmitters and wireless chargers is that, instead of the existing plug-in-mounted wired charger (OBC; on-board charger), the user can wirelessly charge the battery without connecting the power source when charging power to the battery. There is. In addition, the advantage of wireless charging can bring about an energy efficiency improvement effect by using the secondary side rectifier circuit and the receiving coil, but the large-capacity long-distance wireless charging method has a limitation on the transmission distance, so many studies are currently being conducted. The purpose of the study is to study the transmitter circuit and receiver circuit of a wireless power transmission device using a primary coil, a secondary coil, and a half bridge series resonance converter, which can transmit power of a non-contact type power transmitter. As a result, a new topology was applied to improve the power transmission distance of the wireless charging system, and through an experiment according to each distance, the maximum efficiency (95.8%) was confirmed at an output of 3 kW at an 8 cm transmission distance.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.111-113
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• 2009

침몰한 잠수함 승조원의 구조용으로 사용되는 구난잠수정은 주 전원과 보조전원으로 축전지가 필수적으로 사용된다. 그러나 사용 중인 축전지 모듈이나 뱅크의 일부 셀(Cell)에 불량이 발생하면 전체 축전지 뱅크의 기능이 저하되어 구난정 시스템을 적절히 운영하지 못하여 제대로 임무를 수행하지 못하거나 커다란 손실을 가져온다. 그리고 축전지에 과 충전이나 과 방전이 발생하면 축전지가 폭발하여 화재가 발생하거나 축전지 내부 구조의 파괴로 더 이상 사용 못하는 경우가 발생한다. 따라서 이와 같이 축전지에 손상을 줄 수 있는 상황을 미연에 방지하여 축전지가 최적의 동작 상태를 유지할 수 있도록 해주고 전체 시스템의 신뢰성을 향상시키기 위하여 본 논문에서는 구조잠수정용 리튬폴리머 (Lithium Polymer) 축전지 관리장치의 개발을 수행하였다. 본 논문을 통해 축전지 관리 장치(BMS : Battery Management System)의 핵심기술인 H/W 및 S/W 설계기술, 각 Cell의 전압 제어기술, SOC(State of Charge) 제어 알고리즘 도출 및 시스템 운영 기술을 구현하였으며 개발된 알고리즘과 기능은 충 방전 부하시험과 한국 선급인증시험을 통해 유효한 방식임을 확인하였다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.532-534
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• 2015

본 연구에서는 'Open Framework 기반 Smart ESS 전력제어 모듈'과 연동을 위해 설계, 제작한 3상 PCS 시제품의 동작 모드별 주요 전기적 특성을 분석하였다. 충전모드에서 운전시 PWM 컨버터의 입력역률, 입력전류 THD 및 전력변환 효율과 방전모드로 운전시 계통으로 주입되는 전류의 역률, THD 및 전력변환 효율을 각각 측정, 분석하였다. 또한 독립운전시 부하량에 따른 PWM 컨버터의 출력전압 THD 및 전력변환 효율을 측정, 분석하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.662-665
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• 2024

IT 기술이 발전하며 실시간 전력 수요량 및 가격 등을 파악할 수 있는 스마트 그리드가 주목을 받고 있다. 스마트 그리드 환경에서는 에너지 저장 장치를 이용하여 소비자의 경제적 부담을 덜어낼 뿐만 아니라 에너지를 효율적으로 사용할 수 있다. 본 연구에서는 이러한 목표를 위해 과거 2시간 동안의 부하량 및 가격을 바탕으로 에너지 저장 장치의 충전 및 방전량을 결정하는 강화학습 알고리즘을 제안한다. 또한, 여러 강화학습 기법의 성능을 비교 분석한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.440-447
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• 2011

This paper deals with supercapacitor energy storage system for the compensation of the slow response characteristics of a fuel cell generation system for grid connection. A bidirectional dc/dc converter is used for the charging and discharging of the supercapacitor. The conventional converters use additional clamping circuit, etc. to reduce a voltage spike at the instant of switching and to provide wide range of soft switching. The proposed method provides simplified hardware implementation without any clamping circuit, and soft switching condition for both charging and discharging mode with proper switching patterns. The usefulness of the proposed scheme is verified through simulation and experimental results with 1 kW system.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.89-90
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• 2015

본 논문에서는 양방향 배터리 충전기를 위한 새로운 대칭 공진형 컨버터를 제안한다. 제안하는 컨버터는 좁은 스위칭 주파수 변동폭으로 넓은 전압범위의 동작이 가능하고 전 부하에서 스위칭 소자의 소프트 스위칭을 성취할 수 있다. 또한 스타트업시 돌입전류에 의한 소자의 전류스트레스가 제한되고 입력과 출력에서 보이는 공진탱크가 대칭적이어서 충전 및 방전시 전압이득곡선이 동일하며, 3차 권선을 통하여 공진 커패시터의 전류정격을 줄일 수 있다. 3kW급 시작품을 제작하여 제안하는 컨버터의 타당성을 검증하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.4
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• pp.100-105
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• 1998

This paper proposes a new control strategy of bidirectional uninterruptible power supply (UPS) with the performance of active power filter which compensates the harmonics and reactive power. With only one power stage, it is working simultaneously as the AC/DC rectifier/battery charger and DC/AC inverter to the operation of battery charging or back-up power supplying. Therefore the operation of the proposed system can be divided into the modes, such as the active power filter mode and the battery back-up power mode. And a novel closed-loop control strategy is used to calculate the reference current. The performance of the proposed 5[kVA] system is verified by the simulation and experimental results.