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전압 리플을 이용해 영전류스위칭하는 두개의 트랜스포머를 가지는 위상천이 풀-브릿지 컨버터
윤현기(Hyun-Ki Yoon),문건우(Gun-Woo Moon),윤명중(Myung-Joong Youn) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
This paper presents a Zero-Current Switching(ZCS) two-transformer phase-shift full-bridge(TTFB) converter using voltage ripple. The proposed converter provides Zero-Voltage Switching(ZVS) of leading leg switches and ZCS of lagging leg switches using voltage ripple. Especially, circulating current is reduced by ZCS operation and there are no additional components required for the soft switching of power switches. Furthermore, in case of light load, ZVS operation of lagging leg can be achieved. The operations, analysis and design consideration of proposed converter are presented. To verify the validity of the proposed converter, experimental results for a 410W (205V, 2A) prototype are presented.
윤현기(Hyun Gi Yoon),David E. Stock,유기수(Ki Soo Yoo),정명균(Myung Kyoon Chung) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Diurnal variation of the flow over a forest canopy on a mountain slope is simulated numerically. In the daytime, the earth surface is heated by the solar radiation and the flow goes up the mountain due to the buoyancy force, and during the night, the air is drained downward along the slope owing to the cooling of the surface by radiation. In this flow process the forest canopy that consists of leaf region and the trunk region plays a dominant role as a momentum sink to the flow, thus the modeling of the leaf area region and trunk region is critical to the successful flow simulation. In the present study, a field measurement in an experimental forest in the State of Oregon in the United States is numerically analyzed. The resistance to the flow in the leaf region is directly related to the leaf area density (LAD), and the trunk is modeled as a cylinder.
수술적 도달법에 따른 고관절 전치환술후의 이소성 골형성
안기찬 ( Ki Chan Ahn ),윤현기 ( Hyun Ki Yoon ),최장석 ( Jang Seok Choi ),김영창 ( Young Chang Kim ),유현덕 ( Hyun Duk Yoo ),서승석 ( Seong Seok Seo ),이영구 ( Young Gu Lee ) 대한고관절학회 1994 Hip and Pelvis Vol.6 No.1
Periarticular heterotopic bone(HB) formation after total hip arthroplasty (THA) was unknown causes yet, but occurs more commonly after procedures in which considerable bone was resected or the soft tissues were dissected extensively. The effect of the lateral and the postero-lateral surgical approaches for THA on HB formation were studied in 210 consecutive patients with 246 THA when reviewed 12 months following the operation. Overall rate of formation of HB after THA was 9. 75% and almost HB maturation occured before six months. Although the lowest incidence of HB formation occured after the posterolateral approach, postoperative hip scores for pain, function and range of motion(ROM) scorea showed no significant difference between groups. Therefore, the ability to achieve adequate pain relief and function with THA is not affected by the type of approach.
학교교실 미세먼지 저감을 위한 공기환경조절시스템 현황분석
이현제(Hyun Je Lee),박병용(Beung Yong Park),송한솔(Han Sol Song),류성룡(Seong Ryong Ryu),윤현기(Hyun Ki Yoon) 대한설비공학회 2021 설비공학 논문집 Vol.33 No.5
In this study, we examined the standards for indoor fine dust concentration and investigate the design of an indoor air conditioning system that could remove indoor fine dust. Based on contents taken from the Nara Market Site, we collected, organized, and analyzed data on air purifiers and air circulators (the representative indoor air quality control systems). Additionally, we also investigated and analyzed the current status and statistics of the maintenance of school air quality control systems in Gyeonggi-Do. According to the current status of maintenance for school air quality management systems among 397 schools in Gyeonggi-do, this study found that air quality control measures were applied the most often in elementary schools, and that the MERV15 grade filter was used the most.
소아 환아의 경골 내에 발생한 동정맥 기형 - 1예 보고 -
박수성,이종석,윤현기,정호욱,Park, Soo-Sung,Lee, Jong-Seok,Yoon, Hyun-Ki,Chung, Ho-Wook 대한근골격종양학회 2008 대한골관절종양학회지 Vol.14 No.1
보고된 반 이상의 선천성 동정맥 기형이 사지에 발생한다. 그러나 주로 연부 조직에 발생하며 골 내에 생기는 경우는 적어 이에 대한 연구가 드물다. 또한 복잡하고 다양한 임상양상 때문에 진단 및 치료가 어려운 것으로 알려져 있다. 20개월 된 소아 여자 환자가 좌측 하지의 외상 없이 발생한 박동성 종괴를 주소로 내원하였다. 저자들은 경골 내에 발생한 동정맥 기형을 경험하고 에탄올 주입을 이용한 색전술로 좋은 결과를 얻었기에 문헌고찰과 함께 보고하는 바이다. More than half of the reported cases of congenital arteriovenous malformations involve the extremities. However, these are predominantly arteriovenous malformations of soft tissues. There are few studies on intraosseous arteriovenous malformations. The clinical features of vascular malformations are not well defined, but are likely to be extremely diverse. So, it is not easy to diagnose exactly and treat intraosseous arteriovenous malformations. The authors noted intraosseous arteriovenous malformation of tibia in a child and had a good result by the use of ethanol embolization. Therefore we include those results along with the literature review.
열전지용(MS<sub>2</sub>, M=Fe, Ni, Co)계 양극의 전기화학적 특성 연구
이정민,임채남,윤현기,정해원,Lee, Jungmin,Im, Chae-Nam,Yoon, Hyun-Ki,Cheong, Hae-Won 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.9
Thermal batteries are used in military power sources that require robustness and long storage life for applications in missiles and torpedoes. $FeS_2$ powder is currently used as a cathode material because of its high specific energy density, environmental non-toxicity, and low cost. $MS_2$ (M = Fe, Ni, Co) cathodes have been explored as novel candidates for thermal batteries in many studies; however, the discharge characteristics (1, 2, 3 plateau) of single cells in thermal batteries with different cathodes have not been elucidated in detail. In this study, we independently analyzed the discharge voltage and calculated the total polarizations of single cells using $MS_2$ cathodes. Based on the results of this study, we propose $NiS_2$ as a potential cathode material for use in thermal batteries.
LCD 백라이트용 트랜스포머 없는 냉음극관(CCFL) 구동 회로
최은석(Eun-Seok Choi),윤현기(Hyun-Ki Yoon),문건우(Gun-Woo Moon),윤명중(Myung-Joong Youn),강문식(Moon-Shik Kang) 전력전자학회 2006 전력전자학술대회 논문집 Vol.- No.-
The conventional cold cathode fluorescent lamp (CCFL) driver for LCD TV has a transformer for each lamp to step up the high sinusoidal waveform from the low input voltage. The transformer used in the conventional topology causes the driver to have bulky size and high cost. This paper proposes a new transformer-less CCFL driver for LCD backlight that is based on the parallel-loaded resonant inverter topology. This resonant topology enables the circuit to supply enough high voltage for CCFL without a transformer. Also, with current-balancing technique, this transformer-less inverter drives 16 CCFL lamps.