• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.616-622
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• 2015

A microgrid which is composed of distributed generation systems, energy storage systems and loads is operated in the grid-connected mode and in the islanded mode. Especially, in the islanded mode, a microgrid should maintain frequency in the allowed range. The frequency is decided by a balance between power supply and power demand. In general, the frequency is controlled by using battery energy storage systems (BESSs) in the microgrid. Especially, droop control is applied to controlling BESSs in the microgrid. Meanwhile, over-charging and deep-discharging of BESS in operation and control cause life-shortening of batteries. In this paper, a fuzzy droop control is proposed to change droop gains adaptively by considering state of charge (SOC) of BESSs to improve the life cycle of the battery. The proposed fuzzy droop control adjusts droop gains based on SOC of BESSs in real time. In other to show the performance of the proposed fuzzy droop control, simulation based on Matlab/Simulink is performed. In addition, comparison of the convention droop control and the proposed fuzzy droop control is also performed.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.45-50
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• 2021

우리나라 서해안 및 동해안지역에는 대규모 발전단지가 집중되어 운영 중이며 이 발전단지들의 발전력을 송전하고 있는 765kV 송전선로 2 회선 고장이 발생하는 경우 송전선로의 용량부족으로 인해서 수 GW 규모의 발전력을 불시에 탈락시키도록 보호체계(SPS, Special Protection System)가 운영 중이다. 이 SPS 가 동작하여 대규모 공급능력이 불시에 상실되면 급격한 주파수 하락이 발생하게 되어 저주파수계전기(Under Frequency Relay, UFR)가 동작할 수 있기 때문에 SPS 탈락 발전기의 출력을 상시에 감소시키는 제약비발전(Constraint off)을 시행하고 있다. 이 제약비발전으로 인해 매년 수천억원의 제약비용이 발생하고 있기 때문에 제약을 완화시키기 위한 방안으로 배터리 에너지저장장치(BESS)를 적용하는 사업이 추진되고 있다. 이는 "발전제약완화 에너지저장장치(이하 발전제약완화용 ESS) 사업"으로 불리며 전국 19 개 변전소에 총 1.4GW(2C-Rate)의 에너지저장장치가 설치되는 국내 최대규모의 BESS 사업이다. 향후 송전망 확충에 의해서 발전제약이 해소되는 경우 주파수 조정용, 재생에너지 변동성 완화용 등의 다목적 ESS 로 활용될 계획이다. 본 보고서에서는 발전제약완화 ESS 사업의 기술적 효과를 실효치 기반의 시뮬레이션(PSS/E v33.3)을 통해서 검토하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1355-1363
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• 2015

In order to maintain customer voltage within allowable limit($220{\pm}13V$), tap operation of SVR(step voltage regulator) installed in primary feeder could be carried out according to the scheduled delay time(30 sec) of SVR. However, the compensation of BESS(battery energy storage system) is being required because the customer voltages during the delay time of SVR have a difficultly to maintain within allowable limit when PV system is interconnected with primary feeder. Therefore, this paper presents modeling of SVR to regulate voltage with the LDC(line drop compensation) method and modeling of BESS to control active and reactive power bi-directionally. And also, this paper proposes the coordination control modeling between BESS and SVR in order to overcome voltage problems in distribution system. From the simulation results based on the modeling with the PSCAD/EMTDC, it is confirmed that proposed modeling is practical tool for voltage regulation analysis in distribution system.

• Journal of the Korean Orthopaedic Association
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• v.54 no.3
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• pp.211-218
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• 2019

Herniation of the intervertebral disc is a medical disease manifesting as a bulging out of the nucleus pulposus or annulus fibrosis beyond the normal position. Most lumbar disc herniation cases have a favorable natural course. On the other hand, surgical intervention is reserved for patients with severe neurological symptoms or signs, progressive neurological symptoms, cauda equina syndrome, and those who are non-responsive to conservative treatment. Numerous surgical methods have been introduced, ranging from conventional open, microscope assisted, tubular retractor assisted, and endoscopic surgery. Among them, microscopic discectomy is currently the standard method. Biportal endoscopic spinal surgery (BESS) has several merits over other surgical techniques, including separate and free handling of endoscopy and surgical instruments, wide view of the surgical field with small skin incisions, absence of the procedure of removing fog from the endoscope, and lower infection rate by continuous saline irrigation. In addition, existing arthroscopic instruments for the extremities and conventional spinal instruments can be used for this technique and surgery for recurred disc herniation is applicable because delicate surgical procedures are performed under a brightness of 2,700 to 6,700 lux and a magnification of 28 to 35 times. Therefore, due to such advantages, BESS is a novel technique for the surgical treatment of lumbar disc herniation.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.506-507
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• 2011

본 논문에서는 신재생에너지의 에너지 백업용으로 사용되어지는 2MVA BESS(Battery Energy Storage System)의 수냉형 PCU(Power Conditioning Unit)을 설계하고 3D 모델링 및 열해석을 통해 열적 안정성을 확인하고 이를 실험으로서 검증한다.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.277-283
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• 1989

For the battery energy storage system (BESS), battery is one of most important parts. Various new type batteries for load shifting are under developing. The lead acid battery technology status such as structure, charge and discharge characteristics, life cycle etc. is reviewed and research trend is also introduced.

• Journal of Korean Institute of Industrial Engineers
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• v.13 no.2
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• pp.129-141
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• 1987

The possibility of human error in operation of nuclear power plant has been proved to be one of the most important factors for safety analysis. This study established the HRA methodology according to THERP steps for performing PRA(probabilistic risk assessment) of nuclear power plants and made two sample calculations : Availibility of auxiliary diesel generator, possibility of Davis-Bess #1 accident in 1985.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.297-298
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• 2012

본 논문에서는 장주기(Long-Term, LT) 배터리 에너지 저장 시스템(Battery Energy Storage System, BESS)용 1MW급 PCS의 계통연계형 멀티레벨 컨버터 및 제어 시스템을 소개하고, 현장 시험을 통한 타당성 검증 결과를 제시한다. 또한 1.5 MW 풍력발전기 출력과 연계한 잉여 전력 충전 및 전력 피크 시간대 방전(Energy Shift) 기능을 통해 피크 부하 시간대 전력 문제에 효과적으로 대응할 수 있음을 확인하였다.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.131-132
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• 2018

The world market for BESS (Battery Energy Storage System) is growing rapidly, and battery technology is also developing. It is important to understand the battery characteristics and develop a control strategy to develop the optimal BMS (Battery Management System). In this paper, we compare and analyze the parameter characteristics of NCM LIB (Lithium Ion Battery) according to the temperature change.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.365-366
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• 2020

본 논문에서는 단상 3.3kW PV-BESS 시스템과 능동전력디커플링 회로를 연계한 스마트 모빌리티 충전시스템을 제안한다. 일반적인 계통 연계 시스템에서 문제가 되는 2차 리플 전력을 능동전력디커플링 회로를 적용하여 제거함으로써 스마트 모빌리티에 안정적인 전력을 공급하고 스마트 모빌리티 충전 시스템의 전력밀도를 높이고 수명을 늘릴 수 있다. 본 논문에서 제안한 시스템은 MATLAB/Simulink 시뮬레이션을 통해 검증하였다.