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DC/DC 승압 컨버터의 출력 특성 개선을 위한 스너버 회로 설계
김성종,김인혁,정구종,손영익,한병문 明知大學校 産業技術硏究所 2009 産業技術硏究所論文集 Vol.28 No.-
Applications of DC!DC boost converters are increasing recently in many industrial areas including renewable energy sources. High switching frequency of the power semiconductor devices including MOSFET, IGBT causes the EMI noise owing to the large values of dv/dt and di/dt. Since the EMI noises degrade power efficiency and reliability of the system many researches have been made to reduce the noise. This paper presents a passive snubber circuit to improve the tum-on and turn-off transients of the pulsewidth modulated (PWM) DC/DC boost converters. The noises in the output voltage of the DC!DC converter are reduced by adding a resistor and an inductor to the circuit. Experimental results show the effectiveness of the proposed snubber circuit to improve the output characteristics of the boost converter.
화상 환자에서 발생한 외과적 중재술을 요하는 감염성 심내막염 2예
김근숙,이태유,정연손,최창순,최민호,류제헌,김철홍,조구영,우흥정 대한감염학회 2003 감염과 화학요법 Vol.35 No.3
감염성 심내막염은 화상 후에 발생할 수 있는 치명적인 합병증이다. 임상 증상은 일반적으로 없는 경우가 대부분이고 지속되는 발열과 양성 혈액 배양 검사가 유일하다. 감염의 다른 확실한 원인 없이 발열과 양성 혈액 배양 검사가 있을 때는 감염성 심내막염을 강력하게 의심해야 하며 심장 초음파로 진단 가능하다. 감염성 심내막염은 사망률은 높지만 초기에 진단하면 항생제 정주를 지속하는 것으로 치료할 수 있다. 저자들은 화상환자에서 발생한 수술적 처치를 필요로 하는 감염성 심내막염 2예를 경험하였기에 보고하는 바이다. Infective endocarditis is a rare but fatal complication following burn injury. The clinical presentation is silent, but with persistent fever and positive blood culture. The manipulation of clinical care as well as the burn wound itself and immunosuppression caused by extensive bums puts the burn patients at risk of bacteremia. Staphylococcus aureus and Gram-negative bacilli are most common pathogens of infective endocarditis following burns. We report herein two cases of infective endocarditis in the burn patients who requires surgical intervention. The first case was caused by Pseudomonas aeruginosa with complication of multifocal pneumonia, and the second case by coagulase-negative stapylococcus with cerebral hemorrhage.
Efficient Derivation and Long Term Maintenance of Pluripotent Porcine Embryonic Stem-like Cells
Son, Hye-Young,Kim, Jung-Eun,Lee, Sang-Goo,Kim, Hye-Sun,Lee, Eugene,Park, Jin-Kyu,Ka, Hakhyun,Kim, Hyun-Jong,Lee, Chang-Kyu Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.1
Porcine embryonic stem (ES) cells have a great potential as tools for transgenic animal production and studies of regulation of differentiation genes. Although several studies showed successful derivation of porcine ES-like cells, these cells were not maintained long-term in culture. Therefore, this study was conducted to establish porcine pluripotent ES-like cells using in vivo fertilized embryos and to maintain these cells in long term culture. Porcine ES-like cells from in vivo embryos obtained by immunosurgery or whole explant culture were successfully cultured for over 56 passages. Morphology of porcine ES-like cells was flat-shaped with a monolayer type colony. These cells stained for alkaline phosphatase throughout the culture. Furthermore, porcine ES-like cells reacted with antibodies against Oct-4, SSEA-1, SSEA-4, Tra-1-60, and Tra-1-81, which are typical markers of undifferentiated stem cells. To characterize the ability of porcine ES-like cells to differentiate into three germ layers, embryoid body formation was induced. After plating of these cells, porcine ES-like cells were spontaneously differentiated into various cell types of all three germ layers. In addition, porcine ES-like cells were successfully derived from IVF blastocysts in media containing human recombinant basic fibroblast growth factor.
Kim, Sun Jae,Choi, Moon-Bong,Park, Mansoo,Kim, Hyoungchul,Son, Ji-Won,Lee, Jong-Ho,Kim, Byung-Kook,Lee, Hae-Weon,Kim, Seung-Goo,Yoon, Kyung Joong Elsevier 2017 Journal of Power Sources Vol.360 No.-
<P><B>Abstract</B></P> <P>As the solid oxide fuel cell (SOFC) technology matures, durability under real operating conditions is considered as one of the most critical issues for commercialization. The severe conditions encountered in practical operation include a large temperature gradient and generation of local hot spots within stacks. Herein, we report the degradation mechanisms of anode-supported planar SOFCs supplied by Posco Energy at elevated operating temperatures. A simple comparison of the voltage reduction rates at different operating temperatures does not appropriately represent the degree of degradation, because the rapid deterioration of the cell components at high temperatures is compensated for by the fast reaction and transport kinetics. A combination of impedance interpretation and post-mortem analysis reveals the major degradation processes that are distinctively accelerated by increasing temperature, including the chemical interaction between the cathode and electrolyte, the enlargement of the interfacial pores, the coarsening of the fine particles in the composite electrodes, the formation of interfacial cracks and Cr poisoning. Systematic analysis presented in this study provides guidelines for counteracting the unexpected temperature increase, and the database established under various extreme conditions would form the groundwork for achieving the lifetime goals of commercial SOFC systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Long-term stability of solid oxide fuel cells are evaluated at various temperatures. </LI> <LI> The impedance spectra are analyzed using the distribution of the relaxation time technique. </LI> <LI> The major degradation processes accelerated by increasing temperature are clarified. </LI> </UL> </P>
Attraction and repellent activity of essential oils against Lycorma delicatula
Han-Goo Ji,Ji-Hyeon Park,Bong-Ki Son,Hwa-Jeong Yeom,Sang-Rae Moon,Changmann Yoon,Chul-Sa Kim,Gil-Hah Kim 한국응용곤충학회 2009 한국응용곤충학회 학술대회논문집 Vol.2009 No.10
Using thirty-one essential oils with different manufactured T-tube olfactometers, attraction and repellent efficacy were proved against ggot-mae-mi, Lycorma delicatula. Among tested essential oils, spearmint was selected to have attraction efficacy (94.1%; P<0.001). Spearmint was also showed attraction efficacy in 10 and 2.5 ul, but did not showed in 1 ul. GC analyzed chemical constituents of spearmint were tested with different concentations (10, 5, 2.5, 1 ul). Carvone were showed activity in 10 and 5 ul, but limonene did not showed the activity. When mixing two compounds were showed activity in 10, 5, 2.5 ul as 78.8, 73.5, and 69.7%, respectively. Lavender was selected to have repellent efficacy (86.7%; P<0.001). Lavender was also showed repellency in 10 and 2.5 ul, but did not showed in 1ul. GC analyzed chemical constituents of lavender were tested with different concentrations, results have the activity linalool and terpinen-4-ol in 10 and 5 ul, but linalyl acetate and caryophyllene oxide did not have the activity. Spearmint and lavender showing attraction and repellency, respectively, were keep in lure during 24 hr for penetration with different concentration(30, 20, 10 ul), and attached to the center of Fly catcher, fly sticky trap. The trap was set in the field that founded frequently the L. delicatula. The number of L. delicatula caught in the traps were counted after 5, 10, and 15 days. In attraction efficacy of 20 ul concentration wㄷre high attracted the insect(P<0.001). 30 ul concentration were also have the high attraction (P<0.01). We are now tested the control efficacy in grapevine orchard using these materials.