• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.163-165
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• 2007

Generally, the power management system of fuel cell hybrid vehicle (FCHV) requires a unidirectional DC/DC converter for the fuel cell (FC) and a bidirectional DC/DC converter for the battery. To manage the various power flows between these modules with a simple way, a new band-gap reference voltage (BGRV) control strategy is proposed. The proposed method easily controls this variable power flow by setting the reference voltages of each converter to slightly different values, and it can be simply implemented by commercial controllers as well. The operational principle of proposed method is presented and verified experimentally by the 400W prototype.

• 전력전자학회논문지
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• 제25권3호
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• pp.219-226
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• 2020

Given the change in the energy market, large energy storage systems (ESS) is rapidly entering the market. In this rapid spread, fire accidents are becoming an issue. This study attempts to approach the fire from the system point of view to analyze the problems caused by bonding from different perspectives. Moreover, to conduct this study, the fabrication of real objects is dangerous, which needs to be verified through simulation. In this study, we approach the cause of fire that occurs in large-capacity ESS from the system perspective. We focus on determining the effects of cell balancing performed on the BMS after charging. Thus, we analyze the cell balancing behavior and the linkage risks to the various stacks. The study also explores why no fire occurs during 70% operation.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 한국컴퓨터종합학술대회논문집 Vol.34 No.1 (B)
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• pp.238-242
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• 2007

최근들어 휴대용 미디어 플레이어(Portable Media Player)와, 노트북 컴퓨터, PDA(Personal Data Assistant)의 사용이 늘어나면서 얼마나 오랜 시간동안 휴대용 장치를 사용하는가에 대한 문제가 큰 이슈로 떠오르고 있다. 그에 대해 많은 연구가 이루어져 있으며, 현재도 활발히 연구가 진행되고 있다. 본 논문에서는 프로세스 상태, 배터리 상태 그리고 응용프로그램 종류로 이루어진 상황을 고려한 동적 전력관리 시스템에 대해서 제안하고 그에 따른 세부적인 모듈에 관한 설명과 실험 결과를 보여준다. 실험결과 제안한 시스템을 적용하지 않았을 경우와 비교하여 약 14%의 전력 손실 감소 효과를 볼 수 있었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.345-346
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• 2014

본 논문에서는 배터리팩의 안전한 충방전 관리를 위해 배터리팩의 전류 제한 지표인 state-of-power (SOP)를 구하는 알고리즘을 제안한다. 직렬 연결된 배터리 팩의 SOP를 구하기 위해서는 각 셀의 배터리 파라미터 추정 과정이 필수적이다. 이를 구현하기 위해 듀얼 확장 칼만 필터 (DEKF)를 사용하였으며 효율적인 운용을 위해 DEKF의 사용량을 줄이는 방안을 제시한다. 실험을 통해 배터리 파라미터 추정 결과를 확인하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.465-466
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• 2015

배터리 관리시스템(BMS;battery management system)의 중요 고려요소인 SOC(state-of-charge) 및 SOH(state-of-health)의 전기적 등가회로 모델 기반 고성능 추정의 전제 조건은 배터리 단자전압의 안정된 실험데이터 확보이다. 그러나, 예상치 않은 에러로 인해 배터리 단자전압에 노이즈 성분이 포함될 경우 SOC 및 SOH 추정알고리즘의 성능저하가 우려된다. 이를 위해, 본 논문은 이산 웨이블릿 변환(DWT;discrete wavelet transform)의 다해상도 분석(MRA;multi resolution analysis) 레벨에 따른 디노이징 최적 성능을 소개하고자 한다. 하드 임계화(hard-thresholding) 및 소프트 임계화(soft-thresholding) 기법에 따른 디노이징 성능 차이를 보이고, 각 임계화 기법 적용 시 디노이징 최적 성능을 보이는 레벨을 선택한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.107-108
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• 2012

본 논문은 당사에서 개발한 800kW Energy Storage System(ESS)의 실증 운전에 관한 내용이다. Battery, PCS(Power Conditioning System), EMS(Energy Management System)로 구성되는 ESS는 평활화, 정출력 제어와 같은 다양한 운전모드의 실현으로 풍력, 태양광과 같은 신재생 에너지가 연계된 계통의 출력 안정화에 크게 기여한다. 본 논문은 Smart Renewable 국책과제로 진행된 800kW 에너지 저장 시스템의 실증운전 결과에 대해 중점적으로 기술하였다.

• 대한후두음성언어의학회지
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• 제6권1호
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• pp.9-15
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• 1995

Bowing of the vocal cords may be due to aging. atrophy. bilateral superior laryngeal nerve paralysis. injudicious vocal cord surgery, of an idiopathic cause. The bowing usually produces a dysphonia characterized by breathiness due to air escape : however, it can produce aphonia. This report reviews vocal function after surgical correction of bowing of the vocal cords for diagnosis and management. The vocal function of 13 patients with sulcus vocalis and 12 patients with vocal cord atrophy was evaluated with the use of a test battery of multidimensional evaluation items. The voice was improved postoperatively in most patients. The voice improvement was reflected objectively in maximum phonation time, mean air flow rate during phonation, stroboscopic findings. sound pressure level range and fundamental frequency range of phonation, and results of acoustic analyses of tape-recorded voice. The vocal function after surgical correction of the sulcus vocalis and vocal cord atrophy was improved postoperatively in most patient, but the results were not satisfactory.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.579-582
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• 2008

PEM Fuel cell system was designed and constructed to use as a power source of unmanned aerial vehicles(UAV) in the present study. Sodium borohydride was selected as a hydrogen source and was decomposed by catalytic hydrolysis reaction. Fuel cell system consists of a fuel cell stack, a hydrogen generation system(HGS), and power management system(PMS). HGS was composed of a catalytic reactor, micropump, fuel cartridge, and separator. Hybrid power system between lithium-polymer battery and fuel cell was developed. The fuel cell system was integrated and packaged into a blended wing-body UAV. Energy density of the total system was 1,000 $W{\cdot}hr/kg$ and high endurance more than 5 hours was accomplished in the ground tests.

• 한국멀티미디어학회논문지
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• 제25권11호
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• pp.1564-1571
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• 2022

Wireless sensor network(WSN) is being used in various fields such as reconnaissance, echelon scale identification, weather observation, etc. using small sensors in an environment without a network infrastructure environment. In addition, WSN uses limited battery power, so study on routing protocols to extend the lifetime of the network is important. PEGASIS, a hierarchical routing protocol, accounts for the majority of energy-efficient routing protocol studies and is well known as a representative protocol. In this study, based on PEGASIS, we propose a protocol that constructs multiple chains rather than one chain using the AoA of nodes. The proposed protocol has the advantage of reducing the transmission distance of nodes and eliminating unnecessary transmissions, thereby increasing energy efficiency compared to the existing protocols.

• 한국컴퓨터정보학회논문지
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• 제24권1호
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• pp.129-135
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• 2019

This paper is part of research and development for stand-alone solar system without commercial power supply. It implements firmware of controller for operation of stand-alone solar system by applying IoT technology and also develops communication modules that allow multiple solar lamps to send and receive data through wireless network. The controller of the developed stand-alone solar system can effectively charge the power generated by the solar module, taking into account the battery's charge and discharge characteristics. It also has the advantage of attaching wireless communication modules to solar lamp posts to establish wireless communication networks without incurring communication costs. In addition, by establishing IoT gateway middleware platform for each installation site, it forms a foundation to operate multiple solar lamp posts into multiple clusters. And, it is expected that the data collected in each cluster will be used to enable configuration and control of operational information, thereby inducing convenience and efficiency of remote operation and management.