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추력 리플을 보상하는 선형 하이브리드 스테핑 전동기의 고성능 제어
황태식(Tai-Sik Hwang),석줄기(Jul-Ki Seok) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
The linear hybrid stepping motors (LHSM) has been widely used due to its simple structure and low cost control. Despite of its attractive features, the conventional LHSM has the multiples of 4th times harmonic reluctance force from excitation current and cogging force from space harmonic of permeance. This paper propose a new LHSM, which the mechanical and electrical phase difference are 45°. The proposed motor shows a unique ability to deliver low detent force and we propose a closed-loop control scheme to attack the ripple force for high performance applications. An analytical and experimental comparison between conventional and proposed LHSM is evaluated to confirm the effectiveness of the proposed modeling and control scheme.
600㎾급 용융탄산염 연료전지 발전시스템용 EBOP 제어시스템
황태식(Tai-Sik Hwang),정우택(Woo-Taek Joung),양병훈(Byung-Hoon Yang),김광섭(Kwang-Seob Kim),권병기(Byung-Ki Kwon),최창호(Chang-Ho Choi) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-
An electrical balance of plant(EBOP) of a 600㎾ molten carbonate fuelcell (MCFC) has to transit from grid-connected(GC) mode to grid-independent(GI) mode when a grid is in a fault conditions. A minimum transition time is limited by four cycle for a 600㎾ MCFC to ride through a grid fault. In this paper, we propose a control algorithm of a 600㎾ EBOP for a MCFC system. The EBOP has three operation modes, i.e., GC mode, GI mode, and grid-synchronized(GS) mode. The EBOP controls output currents in a GC mode and regulates output voltages in GI or GS mode. GS mode is defined as an interface between GC mode and GI mode to make a mode transition smooth, i.e., limitation of inrush currents, regulation of output voltages within ANSI standard. Simulations and experiments carried out to verify the effectiveness of the proposed control algorithm.
황태식(Tai-Sik Hwang),김형수(Hyeong-Su Kim),김윤현(Yun-Hyun Kim),김광섭(Kwang-Seob Kim) 전력전자학회 2009 전력전자학술대회 논문집 Vol.2009 No.2
발전용 연료전지 시스템은 수소와 산소를 공급받아 직류전기와 열로 변화시키는 연료전지 스택, 연료전지 스택에 연료와 공기를 공급해주는 MBOP(Mechanical Balance Of Plant), 연료전지의 출력을 계통에 연계시키는 EBOP(Electrical Balance Of Plant)로 구성된다. EBOP 시스템은 병렬 연결된 1.5㎿ PCU(Power Conversion Unit)로 구성되며, 각 PCU는 750㎾ 인버터가 병렬로 구성된다. 본 논문에서는 4병렬로 구성된 3㎿급 연료전지용 EBOP의 병렬제어 알고리즘을 소개한다. 제안한 병렬제어 알고리즘은 과도응답이 빠르고 순환전류가 없는 제어특성을 가진다. 그리고 시뮬레이션과 실험으로 제안한 알고리즘의 성능을 확인한다.
김형수(Hyeong-Su Kim),황태식(Tai-Sik Hwang),김왕래(Wang-Rae Kim),정우택(Woo-Taik Jung),임창진(Chang-Jin Lim),김윤현(Yun-Hyun Kim),김광섭(Kwang-Seob Kim) 전력전자학회 2009 전력전자학술대회 논문집 Vol.2009 No.2
EBOP(Electrical Balance of Plant)는 직류의 연료전지의 출력을 전력전자기술을 이용해 계통전원에 연계 가능한 교류로 변환해주는 일련의 시스템을 칭한다. 포스콘에서는 용융탄산염 연료 전지(Molten Carbonate Fuel Cell, MCFC)를 이용한 3MW 발전용 연료전지 EBOP 시스템을 개발하였으며, 국제규격(IEEE std.1547, UL1741)에 준하는 시험을 통해 성능검증을 완료함으로써 ㎿급 EBOP 시스템의 국산화에 성공하였다.
정성필,장석준,고재욱,임태호,최영환,이한식,황태식 대한응급의학회 2000 대한응급의학회지 Vol.11 No.1
Background. When patients return to the emergency department shortly after being seen, it is generally assumed that their initial evaluation or treatment was inadequate. But in other aspects many short term revisits may be unnecessary in the aspect of emergency care because it is known that substantial numbers of patients use emergency department for nonemergency problems. So we analysed the tendency and the cause of short term revisit patients, determined the rates and the associated demographic, clinical, disease variables as a tool of quality assurance. Method. We carried out a chart review of patients seen in the emergency department, who revisited within 72 hours, of Young Dong Severance Hospital retrospectively between January 1, 1998 and September 30, 1999 (period 2), and compared with result between April 1, 1990 and March 31, 1991 (period 1) respectively. Results. In the period 1, the total revisit patients were 204/21,025 (0.97%), in that period scheduled revisits were 15.2%, the unscheduled were 84.8%, and the frequent revisits (more than 3 times) were 6.4%. In the period 2, the total revisit patients were 4,722/72,802 (6.49%), in that period scheduled revisits were 86.3%, the unscheduled were 13.7%, and the frequent revisits were 24.8%. The most common cause of revisit during the period 2 is a drug addictor (31.2%) that frequently used the emergency room for seeking drug. Conclusion. The scheduled revisit patients for dressing, medication, re-evaluation were increased enormously, so the medical care of these patients might be a part of job that performed in emergency department. And if the health care system could support the adequate nursing care facility, the portion of avoidable revisits of emergency department can be decreased. We also found that the emergency department is an important points for the early identification and referral for the treatment of patients who revisited emergency room for seeking drug, and the analysis of physician related factor in revisits patients may be used as a tool of quality assurance in the emergency department.