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>

한국인에서 일광 노출의 유해성에 대한 인지도와 일광 차단제의 이용 행태에 대한 연구

김상태,김기호,오선진,이승철,강세훈,윤재일,김진준,박석범,김홍용 대한피부과학회 1999 大韓皮膚科學會誌 Vol.37 No.6

Background: Although deleterious effects of sunlight have been increased recently, the surveillance of the attitudes toward sun-exposure and the behavioral aspect of using sunscreens in Koreans has hot been carried out. Objective: Our purpose was to evaluate the attitude toward the harmfulness of sun-exposure and behaviors of using sunscreens in Korea. Method: Five hundred and fifty-two subjects were surveyed to assess the attitude toward sun-exposure, as well as the subjects knowledge about, and the use of sunscreens. Underlying data including demographic data, skin colors, skin types, occupation, and sun-exposure, were obtained. Results: Fifty-four percent of subjects believed that sun-exposure is bad for their skins, but, on the contrary, 12.5% believed it to be beneficial. Fifty-two percent of subjects used sunscreens. Almost all subjects(93.8%) knew why to use sunscreens but 62.7% of subjects did not know the meaning of sun protective factors(SPF). Women, indoor workers, subjects less than 40 years old, with less sun-exposed, fair colored skin, or with skin type I, II, III tended to know the deleterious effects of sunlight and the meaning of SPF and used more sunscreen. Conclusion: High risk population-men, outdoor workers, subjects oider than 40 years old, with more sun-exposed, dark colored skin, or skin type VI, V could be targeted with campaigns that promote attitudinal and behavioral changes.

기종성 방광염을 동반한 기종성 신우신염 1예

김선두,김순제,이길도,김정수,김지훈,윤호상,송종오,문언수 대한노인병학회 2000 Annals of geriatric medicine and research Vol.4 No.3

Estimation and Comparison of Cortical Thickness Index and Canal‑to‑Calcar Ratio Using Manual Method and Deep Learning Method

Sun‑Jung Yoon,Minwoo Kim,Il‑Seok Oh,Kyungho Kim,한갑수 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

Manual calculation of the cortical thickness index (CI) and canal-to-calcar ratio (CC) using radiographs has been widely used. The purpose of this study was to investigate the diference between manual gold standard and automatic calculation based on deep convolutional neural networks (CNNs) of the proximal femur. We obtained institutional review board approval to utilize previous radiographs for the study and the radiograph images were used to train CNN architecture. The calculation experiment of a dataset of 136 images of the proximal femur to estimate CI and CC was performed using a trained CNN architecture (Automatic). Also, manual segmentation method (Manual) to calculate CI and CC was conducted using the standard protocol by two experts as a reference for the results comparison. The mean values of the Manual and Automatic calculation of CI for the proximal femur were 0.56 and 0.54, respectively, showing a statistically signifcant diference (p=0.035). Signifcant diference (p<0.001) was also seen in the calculation of CC by Manual and Automatic method resulting in 0.42 and 0.47, respectively. In addition, the automatic method showed far better results in terms of calculation speed (less than 30 s per single image). Therefore, we suggest that the manual method be carefully considered while planning a surgery.

정신장애인 치료에 중요 역할 담당자의 정신질환에 대한 태도조사

김병후,정선욱,강연화,김윤,김창엽,홍진표,한오수,조맹제,김용익 大韓神經精神醫學會 1996 신경정신의학 Vol.35 No.5

Objectives : Attitudes of families of mentally ill, health personnels and community leaders to the mentally ill after the development and utilization of the community mental health program and reintegration of the chronically ill patients into society. This study was designed to compare the attitudes toward the mentally ill patient of the persons who have important role in treating the mentally ill and to find the variables influencing the attitudes. Methods : We measured attitudes toward mental illness in psychotic patients' families(N=139), community leaders(N=180) and health personnels(N=324) including mental health personnels before the implementation of community mental health services in Yonchon county and Seodaemun district area. The instrument used to measure attitudes was Opinion about Mental Illness(O. M. I.) scale. Results : 1) Health personnel showed lower Authoritarianism(Factor A) and higher Benevolence(Factor B) scores on the average than community leaders and psychotic patients families. 2) Current residence affect the attitudes in psychotic patients' families, not in community leaders and health personnels. Families in urban area showed lower Authoritarianism(Factor A) and Social Restrictiveness(Factor D) and higher Benevolence(Factor B) scores than in the rural areas. 3) Many patient variables were correlated to the attitudes of families. Duration of illness, number of recurrence, number of admission, age of patient and family burden were positively correlated mainly to Social Restrictiveness(Factor D). 4) Sex and religion of respondents showed no or weak relationship with the factor scores. Conclusions : Education for community leaders and families is required to achieve successful community mental health services. Community support program should be developed for chronic, recurrent and burdensome psychiatric patients in the first place.

단기교육으로 시행가능한 심실기능평가법

김원,임경수,오병연,홍은석,김영식,김선만,이부수,현석천,김영득 대한응급의학회 2000 대한응급의학회지 Vol.11 No.4

Background: The initial history, physical examination, and ECG assessment should focus on identification of potentially serious noncardiac or cardiac disorders, including coronary artery disease, congestive heart failure, and electrical instability at the emergency room. additionally, it is essential to define disease severity, stability and need for emergency therapy. echocardiography is a useful tool for this purpose. especially Doppler echocardiography may be more sensitive and time-saving diagnostic tool for the evaluation of patients presenting with cardiogenic symptoms. So we evaluate the feasibility of the echocardiographic measurement by emergency physicain after short-term course. Method and Results: Twenty volunteers(10 male, 38.8±9.3 years) were included in the study for measurement of myocardial performance index and established parameters of ventricular function using conventional echo-Doppler methods. Myocardial performance index: (ICT+IRT)/ET, was obtained by subtracting ejection time(ET) from the interval between cessation and onset of the mitral inflow velocity to give the sum of isovolumic contraction time(ICT) and isovolumic relaxation time(IRT). The most of mean values of echocardiogrphic parameters were not significantly different between those of cardiologist and those of emergency physicians(p<0.01). The duration for measuring myocardial performance index was shortest among echocardiographic parameters. the validity of echocardiographic parameters measured by emergency physicians was proved relatively good. Conclusion: It is proved to be feasible for emergency physician to perform echocardiographic evaluation of ventricular function after short-term course

위절제술 환자의 표준진료지침 개발 및 적용 효과

김은희,김철규,이순교,김순덕,이혜옥,권정순,이경미,이민미,심순미,유용만,신종식,강은희,이상일,김병식,오성태,육정환,박수길 한국의료QA학회 2003 한국의료질향상학회지 Vol.10 No.2

Background : Gastric cancer is the most common malignant tumor in Korea. surgical operation is one of the major treatment modalities for gastric cancer patients. Therefore, gastrectomy is one of the most common procedures in General Surgery. There were variation in length of hospital stay and medical treatment for gastrectomy between three surgeons at Asan Medical Center. Clinical pathways have received considerable attention as a tool for recucing the medical practice variation, increasing the efficiency of care process, and improving the quality of care. The aim of this study was to evaluate the effect of a clinical pathway for gastrectomy in gastric cancer patients. Methods : The clinical pathway for gastrectomy was developed and implemented by a multidisciplinary group in Asan Medical Center. A computerized clinical pathway program was developed and revised after a pilot test. A total of 145 patients underwent gastrectomy by three surgeons at Asan Medical Center. We compared the length of hospital stay, patient satisfaction, and unplanned readmission rate between the pre-pathway group(n=67) and the post-pathway group(n=78). We also investigated the degree of satisfaction among the physicians and nurses who were main end-users of the clinical pathway. Results : The clinical pathway was applied to all target patients. The average length of hospital stay was shortened from 12.7days to 10.6days(p<0.01). The degree of patient satisfaction with the care process changed from 90.3% to 89.2% after the implementation of the clinical pathway, but the difference was of satistically significant(p=0.761). Unplanned readmission rate was 2.9% in the pre-pathway group. More than 90% of physicians and nurses answered that the clinical pathway had been a useful tool in their medical practice. Conclusions : The findings of the study demonstrated that implementation of the clinical pathway for gastrectomy produced substantial reduction in the length of hospital stay while improving the quality of patient outcomes. The computerized clinical pathway program can be used as one of the powerful patient management tools for reducing the practice variations and increasing the efficiency of care process in Korea hospital settings.

HDPE 개질 아스팔트 혼합물의 강도 및 변형특성

김광우,이기호,권오선,고태영 강원대학교 부설 석재복합신소재 제품연구센터 2004 석재연 논문집 Vol.9 No.-

본 연구는 폐비닐 펠렛을 도로포장재료로 재활용하여 자원절약 및 아스팔트 혼합물의 품질향상을 위한 연구이다. 이를 위하여 폐비닐의 첨가량별 배합설계를 수행하여 적정 폐비닐 첨가량과 최적 아스팔트 함량으로 편마암과 화강암 2가지 골재와 폐비닐인 RHDPE의 함량을 4가지로 혼합물을 제작하여 8종류의 재질 혼합물과 2종류의 무개질 혼합물을 제작하였다. 그리고 이 공시체에 대하여 마샬안정도, 간접인장강도 및 Kim test와 반복주행시험 등 실내시험을 통하여 혼합물의 특성을 분석하였다. 폐비닐 첨가량은 RHDPE가 8%일 때 안정도와 간접인장강도 모두 가장 우수한 것으로 나타났고 취성도 나타나지 않았다. RHDPE를 첨가한 혼합물에 대하여 Kim test를 수행한 결과 DR과 DS 모두 높은 상관성을 보였다. 그리고 반복주행시험에서는 RHDPE를 첨가한 혼합물이 일반 혼합물보다 우수하였다. 향후 많은 실험을 통해 RHDPE의 우수성을 입증한다면 소성변형 저항성에 우수한 재료로 이용될 수 있을 것이다. This study is a fundamental research for recycled high-density polyethylene (RHDPE) in asphalt mixture for improving roadway pavement. Marshall mix design was conducted and optimum asphalt content(OAC) was determined for dense-graded surface course mixture by RHDPE content. Marshall stability test, indirect tensile strength (ITS) test, wheel tracking trest and Kim-test were carried out to measure the characteristics of RHDPE-added asphalt concretes. From the results of this study, RHDPE in asphalt mixture if possible. It could be considered that adding too much RHDPE in asphalt mixture is not proper. The optimum content of RHDPE was appeared to be 8%. In Kim-test, statistical analysis was performed for each loading head and aggregate to find out correlation between S_(D) values and each rut parameter. The analysis result showed that S_(D) had very high coefficient of determination with rut parameters on the average.

Analysis of the Motion of a Harmonic Oscillator Coupled to Faraday's Law

KIM*, Se-Hun,KO, Tae-Eon,LEE, Se-Hyun,KIM, Kwang-Sun,OH, Seung-Won,KIM, Hyun-Seok Korean Physical Society 2018 새물리 Vol.68 No.1

하천의 자연도 평가 및 활용에 관한 연구 : 진주시 지방하천을 대상으로

김종오,김옥선,김선혜 경상대학교 생산기술연구소 2001 工學硏究院論文集 Vol.1 No.-

The purpose of this study was to develop the environmental management strategy of streams based on the quantified evaluation method for the stream environment. The six streams in Jinju City flowing into the Nam-River were selected for case study. The stream environment evaluation was performed considering the following three independent field surveys. First, the stream naturalnesses considering 20 evaluation elements were investigated for each unit section of the streams having the length of 500m and the width of 100m, and then were evaluated into 5 grades. Second, water qualities of the steams were evaluated into 5 grades based on eight times of water quality survey for the period from July 2000 to September 2001. Third, the landuse patterns of the stream basins were evaluated into 5 grades according to the residential area ratio. Finally, the stream environments were classified into 5 grades considering the above three subfactors - stream naturalness, water quality, and residential landuse. According to the evaluation results of stream environments, the three environmental management strategies of streams were suggested. As the results of the case study, Panmun stream and Ghajwa stream were evaluated to forth grade that need active environmental restoration, and Nabul stream was evaluated to third grade that need partial environmental restoration while Youngchun river and Dogsan stream were evaluated to first grade showing the desirable stream environmental condition. The above environmental evaluation results for each stream will be an important reference for further stream restoration or management plan.