• 전력전자학회논문지
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• 제10권5호
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• pp.494-500
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• 2005

본 논문에서는 플라이휠에너지를 이용한 다이나믹 UPS 시스템에서 유도기를 이용하여 플라이휠의 에너지를 저장 및 재생하는 시스템 제어 기법을 제시하였다. 유도발전기의 슬립주파수 제어와 벡터제어 기법의 특성을 비교하고, 또한 벡터제어 기법을 사용 시 전동 모드에서 발전 모드로의 전환할 때 직류링크 커패시터 전압의 과도 특성을 개선하는 기법을 개발하였다. 32비트 DSP를 사용한 실험을 통하여 이 기법의 성능을 확인하였다.

• 상하수도학회지
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• 제27권6호
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• pp.711-721
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• 2013

Optimal operation of a combined sewer network with distributed storage facilities aims to use the whole retention capacity of all reservoirs efficiently before overflows take place somewhere in the considered network system. An efficient real-time network control (RTNC) strategy has been emerging as an attractive approach for reducing substantially the overflows from a sewer network compared to the conventional fixed or manually adjusted gate setting method, but the related concrete framework for RTC development has not been throughly introduced so far. The main goal of this study is to give a detailed description of the RTNC systems via reviewing several guidelines published abroad, and finally to suggest methods for the proper application of RTNC on distributed storage facilities. Especially, this study is focused on emphasizing the importance of hierarchical structure of RTNC system that consists of three control layers (management, global control and local control). Further, with regard to the global control layer which is responsible for the central overall network control, the wide-ranging details of two components (adaption and optimization layers) are also presented. This study can provide the valuable basis for the RTNC implementation in the particular sewer network with distributed multiple storage facilities.

• Journal of Power Electronics
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• 제17권6호
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• pp.1625-1636
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• 2017

A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.

• 한국기록관리학회지
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• 제19권3호
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• pp.271-292
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• 2019

최근 중앙행정기관은 업무관리시스템을 클라우드 기반의 온나라2.0으로 변경하였다. 국가기록원은 클라우드 업무관리시스템의 기록을 이관받아 관리할 수 있도록 클라우드 기반의 기록관리시스템을 개발하여 보급하고 있다. 클라우드 컴퓨팅의 이점을 극대화하여 기록관리가 보다 효과적 효율적으로 이루어지도록 재설계할 수 있는 기회이다. 전자기록 관리의 프로세스와 방법이 종이기록 관리방식을 단순히 전자화하는 것에서 탈피하여 디지털 기술에 따른 변환(Transformation)의 수준으로 나아갈 수 있는 기회이기도 하다. 첫째, 이관의 방식을 변환해 볼 수 있다. 업무관리시스템과 기록관리 시스템이 클라우드 저장소를 공유하게 되면 처리과에서 기록관으로 기록물 이관 시 콘텐츠 파일들을 물리적으로 이동시키지 않고 메타데이터만 복사하는 방식으로 이관할 수 있어 비용이 줄고 무결성 훼손 위험이 줄어들 수 있다. 둘째, 기록물의 저장공간 할당에 대한 전략을 구상해 볼 수 있다. 클라우드 저장소를 업무관리시스템과 기록관리시스템이 공유하는 것을 전제로 한다면 콘텐츠 파일들을 저장할 때 기록의 보존기간에 따라 저장하는 위치를 구분함으로써 이점을 얻을 수 있다. 셋째, 기록의 생산시스템, 기록관리시스템, 정보공개시스템 등 콘텐츠에 접근하는 시스템들이 클라우드 저장소를 공유하게 되면 콘텐츠의 중복을 최소화하는 방향으로 설계를 전환할 수 있다.

• 자원환경지질
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• 제53권4호
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• pp.491-504
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• 2020

지속적인 기후변화와 지구온난화로 인해 2015년 12월 프랑스 파리에서 열린 제21차 유엔기후변화협약(UNFCCC) 당사국총회(COP21)에서 모든 당사국(195개국)이 온실가스 감축에 참여하는 파리협정이 체결됨에 따라 전 세계적으로 온실가스 감축에 대한 다양한 기술이 거론되고 있으며, 그 중에 CO₂를 감축시키는 것이 가장 효율적이라고 분석 되었다. 이에 따라 CO₂ 포집/저장/활용 기술(CCUS)은 CO₂ 감축의 실질적인 기여를 할 수 있는 수단으로 주목받았으며, CCUS기술 분야에 대해서 많은 국가들의 연구개발 활동이 활발히 이루어지고 있다. 따라서 본 연구에서는 이산화탄소 포집/저장/활용과 관련된 기술의 특허 동향 분석을 통해 CCUS 연구개발 및 전략적 지원방안 수립에 근거를 제시하고자 한다. 특허 분석은 미국, 한국, 일본, 유럽, 중국의 특허를 검색하여 총 10,137건을 수집하였고, 국가별 특허분석 결과 미국의 수가 가장 많았다. 기술별 분석에 따르면 포집에 관한 기술이 60%로 높았지만, 최근에는 활용에 관한 기술이 점점 증가하고 있는 것으로 나타난 만큼 이에 대한 기술 실증과 연구개발 및 정책적 지원이 지속적으로 이루어져야 될 것으로 보인다.

• 설비공학논문집
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• 제16권6호
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• pp.574-583
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• 2004

In this study, the operation strategy of the radiant floor cooling is evaluated in terms of indoor environmental conditions and energy consumption through simulations using the TRNSYS comparing the existing cooling operation. The operation strategy during continuously operated for cooling is proposed that a representative room had additional equipments and other rooms were operated with only a radiant floor cooling system and that system and control method for cooling are varied with period while intermittently operated for cooling. Specifically, when there are no people in the room, rooms were operated by only radiant floor cooling system using cooling storage and when people are occupied, rooms were operated by dehumidification and supplementary cooling device with radiant floor cooling system. The results of this study show that proposed operation strategy can stably maintain the set room air temperature and can reduce the energy consumption compared to the existing cooling method during continuously operated for cooling. While intermittently operated for cooling, the difference of set room air temperature by proposed operation strategy does not happen, satisfying comfort standards and the radiant floor cooling can expect to supply stable electric power because of decreasing demand for peak electric power of energy consumption.

• Journal of Power Electronics
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• 제18권1호
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• pp.34-44
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• 2018

This paper presents a pulse-width adjustment (PWA) strategy for a novel bidirectional DC-DC boost converter to improve the performance of the dynamic inductor current response. This novel converter consists of three main components: a full-bridge converter (FBC), a high-frequency isolated transformer with large leakage inductance, and a three-level voltage-doubler rectifier (VDR). A number of scholars have analyzed the principles, such as the soft-switching performance and high-efficiency characteristic, of this converter based on pulse-width modulation plus phase-shift (PPS) control. It turns out that this converter is suitable for energy storage applications and exhibits good performance. However, the dynamic inductor current response processes of control variable adjustment is not analyzed in this converter. In fact, dc component may occur in the inductor current during its dynamic response process, which can influence the stability and reliability of the converter system. The dynamic responses under different operating modes of a conventional feedforward control are discussed in this paper. And a PWA strategy is proposed to enhance the dynamic inductor current response performance of the converter. This paper gives a detailed design and implementation of the PWA strategy. The proposed strategy is verified through a series of simulation and experimental results.

• 산업공학
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• 제23권4호
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• pp.311-318
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• 2010

In the daily multi-reservoir operating problem, monthly storage targets can be used as principal operational guidelines. In this study, we tested the use of a simple back-propagation Artificial Neural Network (ANN) model to derive monthly storage guideline for daily Coordinated Multi-reservoir Operating Model (CoMOM) of the Han-River basin. This approach is based on the belief that the optimum solution of the daily CoMOM has a good performance, and the ANN model trained with the results of daily CoMOM would produce effective monthly operating guidelines. The optimum results of daily CoMOM is used as the training set for the back-propagation ANN model, which is designed to derive monthly reservoir storage targets in the basin. For the input patterns of the ANN model, we adopted the ratios of initial storage of each dam to the storage of Paldang dam, ratios of monthly expected inflow of each dam to the total inflow of the whole basin, ratios of monthly demand at each dam to the total demand of the whole basin, ratio of total storage of the whole basin to the active storage of Paldang dam, and the ratio of total inflow of the whole basin to the active storage of the whole basin. And the output pattern of ANN model is the optimal final storages that are generated by the daily CoMOM. Then, we analyzed the performance of the ANN model by using a real-time simulation procedure for the multi-reservoir system of the Han-river basin, assuming that historical inflows from October 1st, 2004 to June 30th, 2007 (except July, August, September) were occurred. The simulation results showed that by utilizing the monthly storage target provided by the ANN model, we could reduce the spillages, increase hydropower generation, and secure more water at the end of the planning horizon compared to the historical records.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.345-346
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• 2016

The grid-connected energy storage systems, which could increase the reliability, efficiency, and cleanliness of the grid is presently restricted by the high cost of batteries. This problems could be solved by batteries retired from automotive services. These batteries can provide a low-cost system for energy storage and other applications such as residential applications and renewable energy integration. This paper gives an overview of technical requirements for the re-use of the electric vehicle batteries in energy storage systems.Firstly, the motivation of research is introduced. Secondly, the technologies needed for the re-use of the battery are introduced such asidentification of the battery characteristics, grading of the aged batteries, identification of the state-of-charge and state-of-health of the battery and suitable power electronic converter topologies. In addition the control strategy to maximize the battery lifespan and bypass the faulty batteries is presented and one-stop solution to implement the above mentioned technologies are also given.

• Journal of Power Electronics
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• 제16권4호
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• pp.1469-1482
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• 2016

In hybrid energy storage systems, supercapacitors are usually connected in series to meet the required voltage levels. Equalizers are effective in prolonging the life of hybrid energy storage systems because they eliminate the voltage imbalance on cells. This study proposes a modularized equalizer, which is based on a combination of a half-bridge inverter, an inductor, and two auxiliary capacitors. The proposed equalizer inherits the advantages of inductor-based equalization systems, but it also offers unique merits, such as low switching losses and an easy-to-use control algorithm. The zero-voltage switching scheme is analyzed, and the power model is established. A fixed-frequency operation strategy is proposed to simplify the control and lower the cost. The switching patterns and conditions for zero-voltage switching are discussed. Simulation results based on PSIM are presented to verify the validity of the proposed equalizer. An equalization test for two supercapacitor cells is performed. An experimental hybrid energy storage system, which consists of batteries and supercapacitors, is established to verify the performance of the proposed equalizer. The analysis, simulation results, and experimental results are in good agreement, thus indicating that the circuit is practical.