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양성자 조사법에 의한 PT-IGBT의 Turn-off 스위칭 특성 개선
최성환,이용현,권영규,배영호,Choi, Sung-Hwan,Lee, Yong-Hyun,Kwon, Young-Kyu,Bae, Young-Ho 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.12
Proton irradiation technology was used for improvement of switching characteristics of the PT-IGBT. Proton irradiation was carried out at 5.56 MeV energy with $1{\times}10^{12}/cm^2$ doze from the back side of the wafer. The I-V, breakdown voltage, and turn-off delay time of the device were analyzed and compared with those of un-irradiated device and e-beam irradiated device which was conventional method for minority carrier lifetime reduction. For proton irradiated device, the breakdown voltage and the on-state voltage were 733 V and 1.85 V which were originally 749 V and 1.25 V, respectively. The turn-off time has been reduced to 170 ns, which was originally $6{\mu}s$ for the un-irradiated device. The proton irradiated device was superior to e-beam irradiated device for the breakdown voltage and the on-state voltage which were 698 V and 1.95 V, respectively, nevertheless turn-off time of proton irradiated device was reduced to about 60 % compared to that of the e-beam irradiated device.
최성환,윤중열,이혜문,공영민,김병기,이기안,Choi, Sung-Hwan,Yun, Jung-Yeul,Lee, Hye-Mun,Kong, Young-Min,Kim, Byoung-Kee,Lee, Kee-Ahn 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.2
This study investigated the high temperature oxidation behavior of Ni-22.4%Fe-22%Cr-6%Al (wt.%) porous metal. Two types of open porous metals with different pore sizes of 30 PPI and 40 PPI (pore per inch) were used. A 24-hour TGA test was conducted at three different temperatures of $900^{\circ}C$, $1000^{\circ}C$ and $1100^{\circ}C$. The results of the BET analysis revealed that the specific surface area increased as the pore size decreased from 30 PPI to 40 PPI. The oxidation resistance of porous metal decreased with decreasing pore size. As the temperature increased, the oxidation weight gain of the porous metal also increased. Porous metals mainly created oxides such as $Al_2O_3$, $Cr_2O_3$, $NiAl_2O_4$, and $NiCr_2O_4$. In the 40 PPI porous metal with small pore size and larger specific surface area, the depletion of stabilizing elements such as Al and Cr occurred more quickly during oxidation compared to the 30 PPI porous metal. Ni-Fe-Cr-Al porous metal's high-temperature oxidation micro-mechanism was also discussed.
최성환,정기수,김인식,태현진,박영재,심정하,안동춘,Choi, Seong-Hwan,Cheong, Ki-Soo,Kim, In-Shik,Tae, Hyun-Jin,Park, Young-Jae,Sim, Jeoung-Ha,Ahn, Dong-Choon 대한수의학회 2006 大韓獸醫學會誌 Vol.46 No.1
This study was aimed to obtain the anatomical information on the location of ostia of left and right coronary artery in 3 weeks old and 6 months old hybrid swine. The each intercommissural distance of 6 months group was twice than 3 weeks old group. The largest sinus was right aortic sinus followed by left and posterior sinus. All left coronary artery ostia in left aortic sinus were located near the right aortic sinus as well as lower than the ostia of right one. Most of the right coronary artery ostia were located at the level of supravalvular ridge of right aortic sinus. In addition the right ostia had more variation than left ones. Comparing to the sites of 3 weeks old pigs, the sites of the right ostia in 6 months group were more variable. These data suggest that the locations of coronary ostia were different with the sites of human's, and changes of the location may be occurred during the growth.
최성환,손창규,김진미,설인찬,Choi, Seong-Hwan,Son, Chang-Gue,Kim, Jin-Mi,Seol, In-Chan 대한한방내과학회 2010 大韓韓方內科學會誌 Vol.31 No.3
Objective : To summarize and make a reference number of antihyperlipidemic herbal plants worldwide. Method : We surveyed all papers of antihyperlipidemic studies using herbal plants in Pubmed database as "hyperlipidemia AND herb", "hyperlipidemia AND herbal", etc. of Default Tag "Title". The number of papers, the formation of experiments, frequency of herbal plants studies, and main studies were analyzed. Result : Total 178 studies were finally selected. The number of papers were rapidly was increased since 1998. RCT studies were most papers(39.9%). Most studies were about plant sterol or plant stanol studies(78%). 10 papers studied about Herbal plants. Crataegus pinnatifida Bunge, Salvia miltiorrhiza Bunge, Alisma orientale(Sam.) Juz. and so forth were relatively studied much. Conclusion : This study produced an overview of worldwide antihyperlipidemic plants. This result may provide a valuable information for development of Korean herbal medicine against hyperlipidemia in the future.
청간플러스(가미청간탕(加味淸肝湯))로 호전된 뇌경색을 동반한 C형간염 환자 1례 및 알코올성 간염 환자 1례
최성환,장문원,박소애,임승민,안정조,조현경,유호룡,설인찬,김윤식,Choi, Seong-Hwan,Chang, Mun-Won,Park, So-Ae,Lim, Seong-Min,An, Joung-Jo,Jo, Hyun-Kyung,Yoo, Ho-Rhyong,Seol, In-Chan,Kim, Yoon-Sik 대한한의학방제학회 2008 大韓韓醫學方劑學會誌 Vol.16 No.2
This study is a clinical report for hepatitic C patient and alcoholic hepatitis patient who were improved by treatment of a herbal viscous extracts(Chunggan plus). We checked up Aspartate-aminotransferase(AST), Alamine-aminotransferase(ALT) and ${\gamma}$-Glutamyl transpeptidase (${\gamma}$-GTP) and compared the level of AST, ALT, ${\gamma}$-GTP after treatment. After medication the level of AST, ALT, ${\gamma}$-GTP was significantly normalized. So we suggested that herbal viscous extracts(Chunggan plus) has effects on hepatitis.
흉비(胸?), 부면(不眠), 변비(便秘)를 동반한 뇌경색 환자의 대황황련사심탕(大黃黃蓮瀉心湯) 치험례
최성환,김진미,장문원,문승희,조현경,설인찬,Choi, Seong-Hwan,Kim, Jin-Mi,Chang, Mun-Won,Mun, Seung-Hee,Jo, Hyun-Kyung,Seol, In-Chan 대한한의정보학회 2009 大韓韓醫情報學會誌 Vol.15 No.2
Objective: The aim of this study is to show one case of cerebral infarction patient with chest discomfort, insomnia and constipation improved by Daehwanghwangryeonsasim-tang. Methods: The patient was treated with herbal medicine (Daehwanghwangryeonsasim-tang) and acupuncture. Changes in symptoms for treatment period were observed. Result: Intensity and frequency of chest discomfort was decreased. Sleep time was increased and constipation was improved. Conclusion: Daehwanghwangryeonsasim-tang is effective on symptoms of the pattern of heart heat and fire-heat.
대요근에 대한 근에너지기법을 이용한 자세이완기법 적용: 사례연구
최성환,홍현표,Choi, Sung-hwan,Hong, Hyun-pyo 대한정형도수물리치료학회 2017 대한정형도수물리치료학회지 Vol.23 No.1
Background: Positional release muscle energy technique (PRMET) is a method joined positional release technique and muscle energy technique. Methods: Subjects those who have low back pain from the acute to chronic phase, were applied PRMET method on psoas major muscle and measured the changes in pain and disfunction. Results: PRMET method is effective for reducing pain and disfunction on psoas major muscle. Conclusions: The advantages of PRMET method are minimized patient inconvenience, shortening of treatment time and effective for improvement. In the future research, methods need to be improved so that this can be applied to other muscles.
러시아-우크라이나 전쟁(러시아의 우크라이나 침공)의 우주전 분석 및 양상 그리고 우주기술 개발시 고려사항
최성환,Choi, Seonghwan 한국우주과학회 2022 우주기술과 응용 Vol.2 No.2
In this article, Russia's space threat assessment and space warfare in the Russia-Ukraine war (Russian invasion of Ukraine) were analyzed and summarized. Considering the probability that commercial satellites will also be potential targets of space warfare, it is suggested that not only military satellites but also commercial satellites develop and apply space technology that can be applied equally to space threats when developing space technology. Necessary space technologies is listed.
우주 쓰레기 제거기술을 활용한 우주무기 개발 개연성 고찰 및 우주기동전(Space Maneuver Warfare)의 이해
최성환,Seonghwan Choi 한국우주과학회 2023 우주기술과 응용 Vol.3 No.2
According to the studies recently published through advanced maui optical and space surveillance technologies (AMOS) Conference 2021, LEO conjunction assessment revolves around not on operating satellites but space debris such as rocket bodies and non-operational satellites, hence suggesting a solution through space traffic management. Against this backdrop, the issue of active debris removal (ADR) has emerged to the surface as an international challenge throughout the globe. In step with this, the United Nations General Assembly approved a resolution calling on nations to halt tests of direct-ascent anti-satellites, to which U.S. and twelve other nations included Republic of Korea were original signatories. ADR techniques are also actively being researched in the civil sector, and these commercial services, if successfully developed, could possibly be utilized for military use as well. As such, this paper will help readers' understanding for the current status of ADR techniques, space threat assessments, on-orbit rendezvous and proximity operations by looking at previous cases, reflecting on space-faring nations' ADR techniques and its development probability in relation to space weapons. As a conclusion, this study will propose the needs of developing space propulsion system by understanding Space Maneuver Warfare in preparation for the future space battlefield.
최성환(Sung Hwan Choi),안재영(Jae Young An),박기웅(Kee Woong Park),이증주(Jeung Joo Lee) 韓國雜草學會 2009 Weed&Turfgrass Science Vol.29 No.4
17종 식물정유가 집파벼와 강피의 생장에 미치는 영향을 조사한 결과 anise, cinnamon, citronella, clove 및 pine oil 등 5종의 식물정유는 약제살포 10일 후에 95% 이상의 살초효과를 나타내었고, 40일 후 까지도 그 효과가 지속되었다. 이들 5종의 식물정유가 직파벼와 강피의 생체중 감소에 미치는 영향을 조사한 결과, 30kg ai ha-1의 처리농도에서 피에 대한 생장억제 효과가 95%이상으로 매우 높았으나, 직파벼에 대한 생장억제도 비교적 높은 수준이었으며, 벼와 피간의 선택적인 살초효과는 없는 것으로 나타났다. This study was conducted to investigate the phytotoxic effect of 17 essential oils on initial growth of direct seeded rice and barnyardgrass. We found that five essential oils (anise, cinnamon, citronella, clove and pine oil) at 30 kg a.i. ha-1 inhibited more than 95% of the growth of barnyardgrass 10 days after application. These herbicidal effects lasted until 40 days after application. Because the phytotoxicity of the essential oils to the direct seeded rice was relatively high, they might be considered as a non-selective herbicide to control barnyrdgrass in organic farming system.