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Cheol-O Yeon,Dong Kwan Kim,Jae-Bum Lee,Jong-Woo Kim,Cheon-Yong Lim,Gun-Woo Moon 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In this paper, a half-bridge (HB) LLC resonant converter which has been used for server power supply, is controlled by digital controller. In order to increase the entire load efficiency of HB LLC converter, a synchronous rectifier (SR) should has a robust control at any condition such as PFC noise or the lack of current sensing. For these reason, digital controller with LLC SR control is preferred in server power supply market. In this paper, the optimal SR ON-time control which operates as a constant ON-time at below region, and the same ON-time of primary switch at above region, is implemented. However, the problems of optimal SR ON-time control still exist. Because of senseless operation, when the ON-time of SR is larger than the half period of LLC resonant tank, the current of converter flows reversely and it will make the big surge current which damage to active devices. From this result, the ON-time of SR should be shorter than the half period of LLC resonant tank. Moreover, in the case of current unbalance in center-tapped rectifier, the conducting time of rectifiers is different due to the parasitic components. Since the powering periods of two SR are different, the SR ON-time of HB LLC resonant converter should be determined by minimum conducting time of rectifiers. This result causes a large conduction loss of body diodes which makes the low efficiency or the reliability problem of LLC resonant converter. Therefore, HB LLC resonant converter with optimal SR ON-time control is implemented and the asymmetric duty control is proposed in this paper, which solves the current unbalance problem in center-tapped rectifier. Therefore, the LLC resonant converter which has wide input variation, can achieve the high efficiency with optimal SR ON-time control and eliminate the current unbalance problem with asymmetric duty control.
Cheol-O Yeon,Jae-Bum Lee,Il-Oun Lee,Gun-Woo Moon Institute of Electrical and Electronics Engineers 2016 IEEE transactions on industrial electronics Vol.63 No.5
<P>A conventional asymmetrical half-bridge (AHB) converter is widely used for dc-dc stage in low-to-medium power system. However, since the asymmetric operation of AHB converter causes the low efficiency over entire load condition, the conventional AHB converter is not usually considered for the candidate of server power system. In order to overcome the problems of the conventional AHB converter, a wide zero-voltage-switching (ZVS) range AHB converter with a clamp switch and a clamp diode is proposed in this paper. The proposed AHB converter (PAHBC) replaces a low-side clamp diode with a MOSFET switch and adds an auxiliary winding, which changes the transformer turns-ratio. From these modifications and the pulsewidth-modulation (PWM) control of clamp switch, the PAHBC can be designed optimally at nominal input condition and obtains additional dc gain at hold-up time condition. These advantages achieve the high conversion efficiency over the entire load condition. The operational principle and analysis of the PAHBC are presented in this paper and verified by a 340-400 V input and 50 V/500 W output laboratory prototype.</P>
Yeon, Cheol-O,Kim, Jong-Woo,Park, Moo-Hyun,Lee, Il-Oun,Moon, Gun-Woo IEEE 2017 IEEE TRANSACTIONS ON POWER ELECTRONICS - Vol.32 No.9
<P>Generally, an LLC series resonant converter (LLC SRC) is an attractive topology for applications, which require wide input variation and high conversion efficiency because of its wide gain capability and soft-switching capability. However, there is a regulation problem in which the output voltage increases as the load current decreases. In this paper, Bode plot and impedance asymptote analysis were conducted to obtain an intuitive sense of the regulation characteristic of LLC SRC under the light-load condition. Moreover, to improve the regulation capability, a new resonant tank with an additional capacitor is proposed. Its design guidelines were determined by Bode plot and impedance asymptote analysis. Therefore, the proposed LLC SRC achieves very light load regulation, while it maintains the advantages of typical LLC SRCs.</P>
A Medium-Maturing, Dull Cultivar ‘Baegjinju 1’
Ha-Cheol Hong,Sae-Jun Yang,Jeom-Ho Lee,O-Young Jung,Chang-Ihn Yang,Yong-Hwan Choi,Yeon-Gyu Kim,Kyu-Seong Lee,Im-Soo Choi,Young-Chan Cho,Myeong-Ki Kim,Jeong-Il Lee,Eung-Ki Jeong,Jae-Hwan Roh,Ki-Jong Ki 한국육종학회 2012 한국육종학회지 Vol.44 No.1
다양한 용도의 가공용 품종을 육성할 목적으로 1995년 하계에 아밀로스함량이 낮은 일품벼 변이체 Ilpum (MNU)-10- 2-GH1-3을 모본으로 하고 양질 내도복성인 서안벼를 부본으로 교배하여 SR21716-30-2-3-1을 선발하여 ‘수원491호’로 계통명을 부여한 후 2003년-2005년 3개년 간 지역적응시험을 실시한 결과 그 우수성이 인정되어 2005년 12월 직무육성 신품종 선정위원회에서 국가목록등재품종으로 선정됨과 동시에 ‘백진주1호’로 명명하였다. 출수기는 보통기 재배에서 평균 출수기가 8월 20일로 ‘화성벼’보다 10일 정도 늦은 중만생종이며, 벼키는 86 cm, 이삭길이는 22 cm로 ‘화성벼’와 비슷하고, 주당수수는 10개로 ‘화성벼’보다 3개 적으나, 이삭당 벼알수는 121개로 ‘화성벼’보다 25개 많다. 도열병에는 안정적이나, 흰잎마름병 및 바이러스병과 벼멸구 및 애멸구 저항성은 약하다. ‘백진주1호’는 성숙기 하엽노화가 늦은 반면 수발아율은 ‘화성벼’에 비해 낮았고, 춘천 냉수처리 검정에서 적고발현은 적었으나, 임실율이 ‘화성벼’보다 낮았으며, 도복에 강하다. ‘백진주1호’는 단원립으로 쌀 외관은 찹쌀과 같은 뽀얀 특성을 지니고 있으나, 아밀로스함량이 11.5%로 메벼와 찰벼의 중간특성이고, 도정율은 ‘화성벼’와 비슷한 특성을 나타냈다. 보통기재배 평균 쌀 수량은 중부평야 2개소 및 남부평야 4개소에서 4.92 MT/ha로 ‘화성벼’와 남평벼보다 8% 적었으며, 재배적지는 중부평야 및 남부평야이다. ‘Baegjinju 1’ is a new Japonica rice variety developed from a cross Ilpum (MNU)-10-2-GH1-3 and ‘Seoanbyeo’ by a rice breeding team of National Institute of Crop Science, RDA, during the period from 1995 to 2005. This variety has heading date of August 23 in central plain area of Korea. It has a good semi-elect plant type and resistance to lodging with strong culm. The number of panicles/hill of ‘Baegjinju 1’ is more than that of ‘Hwaseongbyeo’, and milled rice of that shows dull and medium short grain. It has very low amylose content (11.5%) and similar gelatinization temperature and good texture characteristics of cooked brown and milled rice compared with ‘Baegjinju’. It has moderate to leaf blast, but susceptible to bacterial blight, virus disease and insect pests. The yield performance of this variety is about 4.92MT/ha in milled rice in local adaptability test for three years (2003-2005). ‘Baegjinju 1’ is adaptable to central and southern plain areas of Korea
간에 단일 종괴 형태로 나타난 특발성 과호산구 증후군 치험
오길찬 ( O Gil Chan ),박상훈 ( Park Sang Hun ),백승훈 ( Baeg Seung Hun ),박철희 ( Park Cheol Hui ),한태호 ( Han Tae Ho ),이동근 ( Lee Dong Geun ),연종은 ( Yeon Jong Eun ),김종혁 ( Kim Jong Hyeog ),변관수 ( Byeon Gwan Su ),박충기 ( 대한소화기학회 2004 대한소화기학회지 Vol.43 No.1
Hypereosinophilic syndrome is characterized by persistent blood eosinophilia of 1,500/㎣ or more in the absence of known causes and multiorgan dysfunction by eosinophil-related tissue damage. In Korea, some cases of hypereosinophilic syndrome with hepatic involvement have been described with prolonged benign clinical courses. Most of them were diffuse or multifocal lesions in imaging studies, and any case presenting as a large single mass lesion has not been described. Herein we report a case of hypereosinophilic syndrome with hepatic involvement in a 48-year-old woman who presented with a giant single mass. By abdominal CT scan, a lobulated well-margined heterogenous mass lesion was detected in the left lateral segment of the liver. Liver biopsy revealed severe eosinophilic infiltration and centrilobular necrosis of hepatocytes. The lesion completely disappeared after steroid administration for eleven months. (Korean J Gastroenterol 2004;43:61-65)