• Journal of the Korean Solar Energy Society
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• v.34 no.4
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• pp.1-7
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• 2014

The microgrid system is the combination of photovoltaic(PV) array, load, and battery energy storage system. The control strategies were defined as multi-modes of operation, including rest operation without use of battery, power charging, and power discharging, which enables grid connected mode or islanded mode. Photovoltaic power is a problem of the uniformity of power quality because the power generated from solar light is very sensitive to variation of insolation and duration of sunshine. As a solution to the above problem, energy storage system(ESS) is considered generally. There fore, in this study, we did basic research activities about optimization method of the amount of energy used, using a smart microgrid test-bed constructed in building. First, we analyzed the daily, monthly and period energy pattern amount of power energy used, and analyzed PV power generation level which is built on the roof. Utilizing building energy pattern analysis data, we was studied an efficient method of employing the ESS about building power consumption pattern and PV generation.

• Journal of Powder Materials
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• v.22 no.1
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• pp.15-20
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• 2015

The composite of porous silicon (Si) and amorphous carbon (C) is prepared by pyrolysis of a nano-porous Si + pitch mixture. The nano-porous Si is prepared by mechanical milling of magnesium powder with silicon monoxide (SiO) followed by removal of MgO with hydrochloric acid (etching process). The Brunauer-Emmett-Teller (BET) surface area of porous Si ($64.52m^2g^{-1}$) is much higher than that before etching Si/MgO ($4.28m^2g^{-1}$) which indicates pores are formed in Si after the etching process. Cycling stability is examined for the nano-porous Si + C composite and the result is compared with the composite of nonporous Si + C. The capacity retention of the former composite is 59.6% after 50 charge/discharge cycles while the latter shows only 28.0%. The pores of Si formed after the etching process is believed to accommodate large volumetric change of Si during charging and discharging process.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.251-256
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• 2006

To design the effective usage of electric double layer capacitors (EDLCs) used for a storage device of dye sensitized solar cell (DSC) energy, we first investigated the accumulation state of electrical charges and the charge behavior in the EDLCs. Based on the results, the voltage characteristics of EDLCs connected to DSC energy were evaluated. The results showed that the charge accumulation region concentrated on the central part of the carbonaceous electrode in EDLCs and the required times for charging and discharging were almost the same.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.673-676
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• 2005

To design the effective usage of electric double layer capacitors (EDLCs) used for a storage device of dye sensitized solar cell(DSC) energy, we first investigated the accumulation state of electrical charges and the charge behavior in the EDLCs. Based on the results. the voltage characteristics of EDLCs connected to DSC energy were evaluated. The results showed that the charge accumulation region concentrated on central part of the carbonaceous electrode in EDLCs and the required times for charging and discharging were almost the same.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.24-25
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• 2013

본 논문은 단일 전류 센서를 이용한 배터리 충방전용 양방향 3상 인터리브드 컨버터의 전류 제어 방법을 제안한다. 기존의 3상 인터리브드 컨버터 전류 제어는 각 상의 인덕터 전류를 센싱해야만 하는 방식이다. 본 논문에서 제안한 전류 제어 방법은 각 상의 인덕터 전류 센싱없이 단일 전류 센싱만으로 인덕터 전류를 제어 할 수 있다. 시뮬레이션을 통하여 본 논문이 제안한 제어 방법의 타당성과 실효성을 증명한다.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.592-596
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• 2004

This paper deals with the operation of a flywheel energy storage UPS. The ups has good features such as long life-time, improved efficiency, no environment problems, reduced size and space, and low maintenance cost compared with the conventional UPS using battery. The operating principle of the UPS is analysed in each mode including charging, voltage compensation, discharging, and voltage unbalance compensation. Especially, the tracking characteristic of the disturbed phase of the source voltage after outage is analysed. The usefulness of the operation is proved through simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.4
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• pp.297-304
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• 2015

A conventional single-phase high-power system typically generates a large AC line input current at universal 90 VAC condition. Sometimes, this phenomenon can block the Earth Leakage Circuit Breaker (ELCB), which causes problems. Replacing power facilities is essential to ensure smooth operations. Thus, this paper proposes a method that can drive higher power than the limit of conventional power facilities. The proposed method can reduce the large AC line input current by limiting the input power of Power Factor Correction (PFC). An additional battery circuit can supplement the power deficiency. Specifically, a bidirectional converter with charging and discharging functions was adopted for the battery circuit. Finally, the validity of the proposed system could be confirmed by modal analysis and simulation, and an experiment in 2 KW condition was implemented with a prototype sample as well.

• Journal of IKEEE
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• v.23 no.4
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• pp.1280-1287
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• 2019

Grid-connected bidirectional PCS(Power Conditioning System) technology is a technology for implementing distributed renewable energy smart grid. And it is always charged by using power collected from solar modules and commercial grid power among vast smart grid systems, and stored when needed.It is a hybrid energy storage device that allows power to be released into the low voltage system. To this end, a PV input power converter with MPPT function, a bidirectional power converter for battery charging and discharging, and a DC Link input are output to a 3 phase 380V AC system, and if nessary, the bidirectional DC/DC converter We designed and developed a PCS with three power converter structures composed of inverters that perform battery charging. Currently, this system is applied to the site of Jeju, which is vulnerable to power outages and fire accidents.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.144-147
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• 2007

최근, 2차전지로서는 타 전지에 비하여 고 에너지 밀도와 고 전압의 특성을 갖고 있는 리튬2차전지가 가장 많이 활용되고 있으며, 이 특성 때문에 전기자동차, 우주왕복선, 분산전원의 한 형태인 전력 저장장치에까지 그 이용이 증대되고 있다. 시스템의 최적성능을 보장하기 위해서는 용도별 싸이클 수명성능을 고려한 충방전 설계 및 이를 위한 전기적 등가모델의 정확성이 필수적이다. 따라서, 본 논문에서는 상용 리튬이차전지의 실제 실험 데이터에 근거하여 충/방전 심도 함수를 도출하고, 리튬이차전지의 수명성능평가를 위한 충/방전 특성 모델을 제안하고, 이의 타당성을 입증하였다.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.245-250
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• 2016

Manganese dioxide is the material which has a good characteristic property for a secondary cell. We have surveyed on rechargeable battery of zink-manganese dioxide using aqueous solution and we also surveyed on redox reversibility of zink-manganese dioxide for checking up possibility for a secondary cell. We have found out to be active for charging and discharging of those.