임상검사물에서의 혐기성세균 분리

권오헌,정윤섭,이삼열 대한미생물학회 1975 大韓微生物學會誌 Vol.10 No.1

Anaerobic bacteria are the major residents of human skin and mucous membrane. The importance, as opportunistic pathogens, of anaerobic bacteria are well recognized because of more population. With decreased defense against bacterial invasion due to chemotherapy, rediation therapy, extensive surgical operation etc. are dealt at hospitals. An analysis of the anaerobe isolation results at Yonsei University Medical Center during the January 1974-May 1975 period was made and the following results were obtained. 1) From 118 patients 146 strains of anaerobes were isolated. Among these 81.3% were nonsporforming anaerobes. Most frequentIy isoIated anaerobes were Pc. Asaccharolyticus, Ps. Anaerobius, Ps. Intermedius, B. fragilis and Cl. Perfriegens. 2) Anaerobes were frequentIy isolated from wound, female genital, intraabdominal, and pleuropulmonary specimens. Fewer anaerobes were isolated from blood, spinal fluid and liver specimens. 3) The ratio of anaerobe isolation to total bacteria isolation were; liver 66. 7%, intraabdominal 33, 3% pleuropulmonary 28. 9%, spinal fluid 5,0% and bIood 4. 2%. 4) Among the 118 anaerobe isolated patients, 48. 3% yielded anaerobes only and rest of them yielded anaerobes together with aerobes. 5) Most of the gram-positive anaerobes were susceptible to the antibiotics tested. Exception was to tetracycline to which appreciable number showed resistance. It was notewarthy that only 48% of B. fragilis was susceptibIe to tetracycline.

Ampicillin과 Chloramphenicol 내성 Salmonella typhimurium 분리의 증가

한상순,권오헌,정윤섭,이삼열,정태화 대한미생물학회 1987 大韓微生物學會誌 Vol.22 No.1

Salmonella typhi infection, which was the most frequent enteric infection in Korea, has been decreasing, while the infectian of other serogroups of Salmonella has been increasing since the later part of 1970s. In 1986, the number of serogroup R isolated by us increased to 46, which corresponds 21.1% of all Enteropathogenic bacteria isolated from stool specimens. Salmonella isolates resistant to antimicrobial agents were extremly rare in Korea, in the 1970s. However, 7 of 13 serogroup R isolates showed resistance to ampicillin or to chloramphenicol in 1984. Among the serogroup B isolates in 1986, 71.7% and 69.6% were resistant to ampicillin and to chloramphenicol respectively. The minimum in- hibitory concentrations of ampicillin and chloramphenicol against these isolates were $gt;128 pg/ml apd 128 pg/ml respectively.

SA 508 강 용접 열영향부의 미세조직과 충격인성의 상관관계

김상호,홍준화,김주학,권순주,이성학,강석영,오세진 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.4

In this study, microstructures of the heat affected zone (HAZ) of SA 508 steel were identified by Mo¨ssbauer spectroscopy in conjunction with microscopic observations, and were correlated with impact toughness. Specimens with the peak temperature risen up to 1350℃ showed mostly martensite, but the microstructures were not changed, much from the base metal because of the minor tempering effect when it was risen to 650℃ or 700℃. With the peak temperature risen to 900℃ over the A₃ temperature, the martensite fraction was reduced, while bainite or martensite island were formed because of the slow cooling from the lower austenite region. As the martensite fraction present inside the HAZ increased, hardness and strengths tended to increase, whereas impact toughness decreased. However, impact toughness of the subcritical HAZ with the peak temperature risen to 650℃-700℃ was seriously reduced after post-weld heat-treatment (PWHT) since carbide particles were of primary importance in initiating voids. Thus, the most important microstructural factors affecting impact toughness were the martensite fraction before PWHT and the carbide fraction after PWHT.

Combustion characteristics of gaseous inverse O₂/H₂ coaxial jet flames in a single-element model combustor

Kim, Tae Young,Choi, Sun,Kim, Young Hoo,Ahn, Yeong Jong,Kim, Hee Kyung,Kwon, Oh Chae Elsevier 2018 ENERGY Vol.155 No.-

<P><B>Abstract</B></P> <P>To effectively design hydrogen (H<SUB>2</SUB>)/oxygen (O<SUB>2</SUB>) liquid rocket engines through understanding the combustion characteristics of H<SUB>2</SUB>/O<SUB>2</SUB> bipropellants, fundamental studies for the bipropellants in different phases are needed. This study is focused on the combustion characteristics of inverse gaseous O<SUB>2</SUB>/H<SUB>2</SUB> coaxial jet flames in a single-element model combustor as a preliminary step for succeeding studies of injection at different phases in the combustor, visualizing flame structure by direct imaging, OH<SUP>∗</SUP> chemiluminescence and OH planar laser-induced fluorescence. With increasing Reynolds number (Re), the frequency of occurrence of the local flame extinction increases and the length of the disconnected OH reaction zone is extended. The OH layer thickness increases downstream, while it is almost constant where the local flame extinction occurs and decreases with increasing Re due to the enhanced strain and scalar-dissipation rates. The excessive flame wrinkledness increases the local flame strain rate and results in the local flame extinction, exhibiting the tendency of increasing and then decreasing flame surface density with increasing Re. The probability density function of OH intensity quantifies the fluctuation intensity of OH radicals and the possibility of the local flame extinction. A useful database is provided for modeling the combustion of H<SUB>2</SUB>/O<SUB>2</SUB> bipropellants under different phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A useful database for modeling the H<SUB>2</SUB>/O<SUB>2</SUB> bipropellant combustion is provided. </LI> <LI> Local flame extinction frequently occurs at high Reynolds number (<I>Re</I>). </LI> <LI> OH probability density function indicates the possibility of local extinction. </LI> <LI> Flame surface density increases and then decreases with increasing <I>Re</I>. </LI> <LI> Strong burning of O<SUB>2</SUB>/H<SUB>2</SUB> causes laminar-like combustion near the injector lip. </LI> </UL> </P>

Effects of Dietary Fatty Acids on Serum Lipids and Fatty Acid Composition of Serum Phospholipids in Men

Oh,Eun-Joo,Kwon,Jong-Sook,Chang,Yu-Kyung 韓國營養學會 1997 Journal of Nutrition and Health Vol.30 No.4

The Computer Algebra Systems in Mathematics Education : A Review of Recent Research

Kwon, Oh-Nam,Shin, Eun-Ju,Shon, Bo-Kyung 이화여자대학교 교과교육연구소 2001 East west education Vol.18 No.-

This study examines the potential role for Computer Algebra Systems(CAS) in such an educational context, particularly their potential to get students more engaged in the learning of mathematics as well as to reduce the "strangle hold" of prerequisite algebraic skills, in courses such as functions, introductory calculus. What is the present status of and near-future outlook for computer algebra in Korean secondary schools? The answer that arises from this review of available fact is: bright with promise, but still dim. Several recent developments have set the stage for an acceleration in the dissemination rate for CAS to high schools. However, this review of some past and present conditions indicates that many years will pass before computer algebra is impacting high school mathematics as much as hand-held calculators are doing now.

H₂-공기와 CO-공기 예혼합 화염 사이의 후류상호작용에 있어서 H₂O 첨가 효과

박정(Jeong Park),권오붕(Oh Boong Kwon),김태형(Tae Hyung Kim),박종호(Jong Ho Park) 한국연소학회 2015 한국연소학회지 Vol.20 No.1

Numerical study was conducted to clarify effects of added H₂O for the downstream interaction between H₂-air and CO-air premixed flames in counterflow configuration. The reaction mechanism adopted was Davis model which had been known to be well in agreement with reliable experimental data. The results showed that both lean and rich flammable limits were reduced in increase of strain rate. The most discernible difference between the two with and without having H₂O and/or H₂ addition into H₂-air and CO-air premixtures was two flammable islands for the former and one island for the latter at high strain flame conditions. Even a small amount of H₂, in which H₂-air premixed flame cannot be sustained by itself, participates in CO oxidation, thereby altering the CO-oxidation reaction path from the main reaction route CO + O₂ → CO₂ + O with a very long chemical time in CO-air flame to the OH-related reaction routes including CO + OH → CO₂ + H with very short chemical times. This intrinsic nature alters flame stability maps appreciably. The results also showed that chemical effects of added H₂O help lean flames at relatively low strain rate be sustained, and suppress the flame stabilization at high strain rates.

H₂-공기와 CO-공기 예혼합 화염 사이의 후류상호작용에 있어서 H₂O 첨가 효과

박정,권오붕,김태형,박종호,Park, Jeong,Kwon, Oh Boong,Kim, Tae Hyung,Park, Jong Ho 한국연소학회 2015 한국연소학회지 Vol.20 No.1

Numerical study was conducted to clarify effects of added $H_2O$ for the downstream interaction between $H_2$-air and CO-air premixed flames in counterflow configuration. The reaction mechanism adopted was Davis model which had been known to be well in agreement with reliable experimental data. The results showed that both lean and rich flammable limits were reduced in increase of strain rate. The most discernible difference between the two with and without having $H_2O$ and/or $H_2$ addition into $H_2$-air and CO-air premixtures was two flammable islands for the former and one island for the latter at high strain flame conditions. Even a small amount of $H_2$, in which $H_2$-air premixed flame cannot be sustained by itself, participates in CO oxidation, thereby altering the CO-oxidation reaction path from the main reaction route $CO+O_2{\rightarrow}CO_2+O$ with a very long chemical time in CO-air flame to the OH-related reaction routes including $CO+OH{\rightarrow}CO_2+H$ with very short chemical times. This intrinsic nature alters flame stability maps appreciably. The results also showed that chemical effects of added $H_2O$ help lean flames at relatively low strain rate be sustained, and suppress the flame stabilization at high strain rates.

Experimental Study on Laminar Lifted Methane Jet Flame Diluted with Nitrogen and Helium

Narayan Sapkal,Won June Lee,Jeong Park,Oh Boomg Kwon 한국연소학회 2014 KOSCOSYMPOSIUM논문집 Vol.2014 No.11

Laminar lifted methane jet flame diluted with nitrogen and helium in co-flow air has been investigated experimentally. This paper examines the role of chemistry, intermediate species responsible for stabilization of lifted flame. To elucidate the stabilization mechanism in lifted methane jet flames with Sc<1, the chemiluminescence intensities of CH<SUP>*</SUP> and OH<SUP>*</SUP> were measured using ICCD camera at various nozzle exit velocities and fuel mole fractions. It has been observed that the OH<SUP>*</SUP> species can play an important role in stabilization of lifted methane jet flame as they are good indicators of heat release rate which can affect on flame speed and increase stability through reduction in ignition delay time.

ALD법으로 제조된 Al₂O₃막의 유전적 특성

김재범(Jaebum Kim),권덕렬(Duk-Ryel Kwon),오기영(Ki-Young Oh),이종무(Chongmu Lee) 한국진공학회(ASCT) 2002 Applied Science and Convergence Technology Vol.11 No.3

지금까지 주로 사용해 오던 TMA(trimethylaluminum, Al(CH₃)₃)와 H₂O를 사용하여 ALD(Atomic Layer Deposition)법으로 증착시킨 Al₂O₃막내의 OH^-기는 Al₂O₃의 우수한 물성을 악화시키는 불순물 역할을 하므로, 이를 개선하기 위하여 본 연구에서는 TMA 와 오존(ozone, O₃)을 이용하여 Al₂O₃막을 증착한 후, 산화제 소스로 H₂O와 O₃을 각각 사용했을 때 그것들이 Al₂O₃막의 유전적 특성에 끼치는 효과에 관하여 비교 조사하였다. XPS 분석결과 O₃를 사용한 Al₂O₃막은 H₂O를 사용할 때와는 다르게 OH^-기가 감소됨을 관찰할 수 있었다. 화학적 안정성(chemical inertness)의 척도가 되는 wet 에칭율 또한 O₃를 사용한 Al₂O₃막의 경우가 더욱 우수하게 나타났다. TiN을 상부전극으로 한 MIS (metal-insulator-silicon) capacitor 구조로 제작된 Al₂O₃막의 경우 H₂O를 사용한 경우 보다 O₃를 사용한 경우에 누설전류밀도가 더 낮았고, 절연특성이 더 우수하였으며, H₂O보다 O₃를 사용했을 때 C-V 전기적이력(hystersis) 곡선의 편차(deviation)가 감소하는 것으로 보아 전기적특성이 더 향상되었음을 알 수 있었다. In the present study Al₂O₃ films were deposited by the ALD technique using trimethylaluminum(TMA) and ozone to improve the quality of the Al₂O₃ films, since the OH^- radicals existing in the Al₂O₃ films deposited using TMA and H₂O degrade the physical and the dielectric properties of the Al₂O₃ film. The XPS analysis results indicate that the OH^- radical concentration in the Al₂O₃ film deposited using O₃ is lower than that using H₂O. The etch rate of the Al₂O₃ film deposited using O₃ is also lower than that using H₂O, suggesting that the chemical inertness of the former is better than the latter. The MIS capacitor fabricated with the TiN conductor and the Al₂O₃ dielectrics formed using O₃ offers lower leakage current, better insulating property and smaller flat band voltage shift (?VFB).