Properties of inverse nonpremixed pure O₂/CH₄ coflow flames in a model combustor

Choi, Sun,Kim, Tae Young,Kim, Hee Kyung,Koo, Jaye,Kim, Jeong Soo,Kwon, Oh Chae Elsevier 2015 ENERGY Vol.93 No.1

<P><B>Abstract</B></P> <P>In order to evaluate the potential of oxy-combustion of inverse nonpremixed coflow flames using a clean fuel to improve the combustion and emission characteristics compared with the normal coflow flames using air, the fundamental properties of inverse nonpremixed pure oxygen (O<SUB>2</SUB>)/methane (CH<SUB>4</SUB>) coflow flames in a model combustor are experimentally investigated. The combustion stability (extinction) limits, structure and nitrogen oxide (NO<SUB>x</SUB>) emissions of the inverse coflow flames in the quartz-windowed combustion chamber with a single shear coaxial injector and a fully opened exhaust nozzle are measured using OH<SUP>∗</SUP> chemiluminescence, a schlieren imaging system and a gas analyzer. Results show four distinct stability regimes and limits: the attached flame regime, the near-blowout flame regime, blowout limits and blowoff limits. The direct flame and OH<SUP>∗</SUP> chemiluminescence images confirm the cooling effects of chamber walls that cause no steady liftoff flame and only the near-blowout flame. The extinction limits of the inverse CH<SUB>4</SUB>/O<SUB>2</SUB> coflow flames are extended compared with the normal CH<SUB>4</SUB>/air coflow flames and reasonable levels of NO<SUB>x</SUB> emissions are observed, which supports that oxy-combustion of the inverse nonpremixed coflow flames using the clean fuel is acceptable for practical application, providing a useful database for modeling the flames in the confined chamber.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Extended stability limits of inverse nonpremixed O<SUB>2</SUB>/CH<SUB>4</SUB> coflow flames are found. </LI> <LI> Stable, attached flames and oscillating, near-blowout flames are observed. </LI> <LI> Direct flame and OH<SUP>∗</SUP> chemiluminescence images indicate no steady liftoff flame. </LI> <LI> Reasonable levels of NO<SUB>x</SUB> emissions are observed. </LI> <LI> Inverse nonpremixed O<SUB>2</SUB>/CH<SUB>4</SUB> coflow flames are acceptable for practical applications. </LI> </UL> </P>

모델연소실 내 압력 변화가 메탄/산소 이원추진제의 연소특성에 미치는 영향

최선(Sun Choi),김태영(Tae Young Kim),김희경(Hee Kyung Kim),권오채(Oh Chae Kwon) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5

메탄(CH4)/산소(O2) 액체이원추진제는 친환경성, 무독성, 경제성, 우수한 성능 등의 장점으로 최근 들어 차세대 친환경 이원추진제로서 각광을 받고 있다. 본 연구에서는 연소실 내 압력 변화에 따른 기체 메탄/산소 비예혼합 동축 화염의 연소안정한계를 측정하고, 화염 및 유동의 가시화를 통해 분사조건 및 압력 변화에 따른 화염의 구조와 특성을 파악하였다. 연소안정한계 측정 결과, 연료과농 조건에서 연소실 내 압력이 증가할 경우 연소안정한계가 확장되는 것이 확인되었고 연소(OH*) 강도 역시 크게 증가하는 것을 확인할 수 있었다. Liquid methane (CH4)/oxygen (O2) bipropellant have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance such as specific impulse and regenerative cooling capability. In this study, the combustion characteristics of gaseous CH4/O2 nonpremixed coflow flames in a model combustor with variation of internal pressure are investigated through measuring the combustion stability limits and visualizing flames and flow. Results show that the combustion stability limits are extended and reaction intensity (OH* intensity) is enhanced with increasing internal pressure of the combustion chamber for fuel-rich condition.

모델연소실 내 GCH₄/GO₂ 및 GH₂ /GO₂ 동축류 제트화염의 연소특성 기초 연구

최선(Sun Choi),김태영(Tae Young Kim),김희경(Hee Kyung Kim),권오채(Oh Chae Kwon) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12

로켓 엔진의 차세대 액체이원추진제로서 각광을 받고 있는 메탄(CH₄)/산소(O₂) 이원추진제의 기초연소특성 및 연소 안정화의 고유특성 확인을 위해 수소(H2)/산소 이원추진제 연소특성과 비교 연구를 수행하였다. 기초 연소특성 연구를 위한 모델연소실 내에서 기체 메탄(GCH₄)/기체 산소(GO₂) 및 기체수소(GH₂)/GO₂의 동축류 제트화염의 연소안정한계와 직접 사진, OH<SUP>*</SUP> 자발광 이미지를 측정한 결과, GCH₄/GO₂와 GH₂/GO₂ 모두 산소-연료 모멘텀비((O/F)mom)가 감소함에 따라 연소안정한계는 확장되는 경향을 보였으나 GH₂/GO₂ 화염에 비해 GCH₄/GO₂ 화염은 좁은 연소안정한계가 측정되었고, 또한 GCH₄/GO₂ 화염은 이론당량비 조건에서, GH2/GO₂ 화염은 연료과농 조건에서 최대 OH* 강도가 측정됨을 OH<SUP>*</SUP> 자발광 가시화를 통해 확인하였다. Liquid methane (CH₄)/oxygen (O₂) bipropellants have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance. To investigate the unique features of CH₄/O₂ bipropellants, the fundamental combustion characteristics of gaseous CH₄/O₂ and H₂/O₂ coaxial jet flames in a model combustor are investigated through measuring the combustion stability limits and visualizing flames. Results show that the combustion stability limits of GCH₄/GO₂ flames are reduced compared with the GH₂/GO₂ flames. The maximum OH<SUP>*</SUP> intensity of GCH₄/GO₂ flames is observed at near-stoichiometric condition, while the GH₂/GO₂ flames at fuel-rich condition.

모델연소실 내 산소-메탄 비예혼합 역확산화염의 연소특성 연구

최선(Sun Choi),김태영(Tae Young Kim),김희경(Hee Kyung Kim),권오채(Oh Chae Kwon) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5

지구온난화로 인한 기후변화에 대응하기 위해 다양한 노력이 요구되는 가운데 연소효율을 증가시키고 공해물질의 배출을 저감할 수 있으며 연소 후 이산화탄소 포집이 용이한 산소-메탄 비예혼합 역확산화염의 연소특성에 대한 연구를 수행하였다. 모델연소실 내에서 산소-메탄 비예혼합 역확산화염의 연소안정한계를 측정하고, 화염구조 파악을 위해 OH* 자발광 기법을 통해 반응영역을 확인하였다. In response to the concern over global warming, there has been substantial interest in either developing high-efficiency or low-emission combustion devices. The use of inverse nonpremixed oxygen (O₂)-methane (CH₄) flames as one possible technology for achieving the high-efficiency and low-emission is considered and thus the combustion characteristics of the oxy-fuel inverse flames in a model combustor are experimentally investigated. The combustion stability limits and structure of O₂-CH₄ inverse flames are measured using OH* chemiluminescence.

헛개 열매와 배 추출물을 첨가한 향신간장 소스의 관능평가

오경희 ( Kyung Hee Oh ),송희순 ( Hee Sun Song ) 한국식품영양학회 2013 韓國食品營養學會誌 Vol.26 No.2

간 기능 개선 및 숙취 해소 효과로 잘 알려진 헛개 추출물을 함유한 간장소스의 개발을 위한 헛개 열매 추출물의 관능 평가 결과, 단향기와 단맛의 강도가 높게 나타났다(p<0.05). 사과, 배, 건무화과, 복분자, 유자, 태양초의 엑기스를 헛개 열매 추출물과 혼합하여 헛개 열매 혼합간장 소스를 만들어 관능 평가하였다. 배를 첨가한 경우에 기호도가 5.0점으로 가장 높았으며, 태양초(4.9점)와 유자(4.5점)도 헛개 열매 혼합간장과 잘 어울리는 것으로 평가되었다. 배, 유자, 태양초 엑기스의 혼합비를 달리하여 만든 혼합간장 소스의 관능평가 결과, 유의차는 없었으나 배만 섞은 경우가 기호도가 가장 높았다. 배의 비율을 높인 경우 기호도가 높게 평가되었고, 유자의 경우 비율을 높이면 향에 대한 특성은 더 좋아지나 기호도 평가는 높지 않았다. 혼합간장 소스에서 헛개 열매 추출물의 첨가 유무에 대해 관능평가하였다. 배-유자-태양초의 경우 헛개 열매 추출물의 첨가 유무에 의한 유의차가 없었으나, 배를 넣은 혼합간장 소스의 경우 헛개 열매를 첨가한 것이 5.6점으로 기호도에서 높은 평가를 받았다(p<0.05). 이러한 결과를 바탕으로 헛개 열매 추출물, 배 추출물, 간장만으로도 기호도가 높은 기능성 향신소스용 조미간장의 개발이 가능할 것으로 제안되었다. The objective of this study was to investigate the sensory quality attributes for the development of soy sauce containing an extract of the fruit of Hovenia dulcis Thunb (Hutgae), also known as liver function improvement and hangover removal. Aqueous extracts of Hutgae fruit and Hutgae fruit-soy sauce were used for determining the sensory evaluation. The intensity of the sweet smell and taste was predominated in the Hutgae fruit extract (p<0.05). Various seasoning items, such as apples, pears, dried figs, Korean bramble (Bokbunja), citron (Yuza) and sun-dried hot pepper (Taeyangcho), were used to determine the suitable type of seasoned soy sauce with the Hutgae fruit extract. In the sensory analysis, the highest overall preference (acceptance score 5) was obtained from the pear extract added to soy sauce with the Hutgae fruit. The overall preference of Yuza (score 4.9) and Taeyangcho (score 4.5) extracts also very well-matched the seasoning items for soy sauce with the Hutgae fruit extract. There was no difference among the extract mixtures of multi-seasoning items added to soy sauce with the Hutgae fruit extract. As more pear extract was added, a higher overall preference was obtained. On the other hand, as the more Yuza extract was added, the higher flavor intensity without the change of the overall preference was obtained. The overall preference of soy sauce with the pear- Yuza-Taeyangcho extract mixture was not different between with or without the Hutgae fruit extract. However, the overall preference (score 5.6) was significantly higher in the pear extract added to soy sauce with the Hutgae fruit extract compared with the pear extract added to soy sauce without the Hutgae fruit extract (score 4.8). These results suggest that soy sauce with the Hutgae fruit-pear extract mixture may be useful as a functional seasoning for various salad dressings.

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>

노인의 영적 간호요구

최미혜,김경희,김귀옥,김기숙,김수강,김정신,김춘숙,노흥진,박지연,성혜연,오명선,이선희,이원옥,이윤영,이현수,장명재,차혜경,채정선,홍상희 중앙대학교 의과대학 간호학과 간호과학연구소 2001 중앙간호논문집 Vol.5 No.1

This study was designed to exam the aged's needs for spiritual nursing care. The purpose was to serve as a basis for the development of spiritual nursing practice. The major findings are as follows : 1. The degree of needs for spiritual nursing care as area was that needs of love and relationship mean 22.0, needs of meaning and object mean 28.2, needs of forgiving mean 13.5. Total needs for spiritual nursing care mean 63.7, which was on the upper middle level. The needs of meaning and object was rated highest. 2. Among the general characteristics of the subjects, needs of love and relatiohship wasn't significanlty different. 3. Among the general characteristics of the subjects, needs of meaning and object was significantly different according to two factors : age(F=7.260, p=0.001), religion(F=5.275, p=0.001). Higher needs of meaning and object was possessed by the older than the younger, by the one who have religion than the other. 4. Among the general characteristics of the subjects, four factors made a significantly difference to needs of forgiving : sex(t=-2.851, p=0.006), age(F=8.201, p=0.001), religion(F=6.928, p=0.000), disease(t=2.327, p=0.024). Higher needs of forgiving was possessed by man than woman, by the older than the younger, by the one who have religion than the other, by the one who have disease than the other.

초·중·고등학교 학생·학부모·일반교사의 보건교육 영역별 요구도와 보건교육

윤순녕,김영임,최정명,조희순,김영희,박영남,오경순,이분옥,조선녀,조소영,한선희,하영미 韓國學校保健學會 2005 韓國學校保健學會誌 Vol.18 No.1

Purpose: The purpose of this study was to identify the needs of health education in students, their parents and teachers in the elementary, middle and high schools and the current situation of health education class. Method: The subjects of this study were a total of 9450 persons including students, their parents and teachers from 279 schools throughout the country. They were selected through convenient sampling. Data were analyzed through x^(2)­test and ANOVA. Result: Students, their parents and teachers replied that 18 dimensions of health education class (DHEC) are necessary. The four DHEC - healthier life style, sex education, mental health and safety education - showed high educational needs in students, their parents, and teacher. High school students had higher educational need of 'symptom management for daily living' than elementary and middle school students. Students, their parents and teachers in elementary school had higher educational needs of 17 DHEC that those in middle and high school. The percentages of schools with health education class taught by health teachers were 99.2%, 75.5% and 66.0% respectively in elementary, middle and high schools. Health education was given mainly using physical education classes at elementary schools, and creative class hours at middle and high schools. In general, health education took 1-3 hours per week at elementary schools, and less than an hour at middle and high schools. Conclusion: Therefore, based on the results, systematic health education class should begin from elementary school to meet the need of health education in students, their parents and teachers, and further study should be made on the number of hours required and the amount of contents of 18 DHEC.

초·중·고등학교 학생, 학부모, 일반교사의 보건교육 요구

윤순녕,김영임,최정명,조희순,김영희,박영남,오경순,이분옥,조선녀,조소영,한선희,하영미 韓國學校保健學會 2004 韓國學校保健學會誌 Vol.17 No.2

Purpose : The purpose of this study was to identify needs of health education of the students, parents, general teachers, and health teacher of the elementary, middle, and high schools. Method : 279 schools of elementary, middle, and high school were sampled nonproportionally during the period from June 28 to July 26, 2004 . The data were collected by the questionnaire from 1,888 students, 1,876 parents, 1,695 general teachers, 279 health teachers. A frequency, % and χ2-test were used to analysis by SAS program. Result : 1. It showed that 98.1% of elementary school students, 92.3% of middle school students, 89.6% of high school students answered that they need health education. The most of students, parents, and general teachers had high interests in health education. 2. In the case of students, main causes of needs of health education was 'to prevent diseases or accidents''. But parents answered that it was 'to build up a healthier behavior'. General teachers answered that it was 'more effective systematic and continuous health education'. 3. Over 80% of students, parents, and general teachers about the question of who qualified person is to teach health education as a regular class responded that health teacher is available. Especially 93% of elementary school students answered like that. 4. The most of students, parents, and general teachers answered that health education in the classroom is favorable 1 to 2 hours per week. Conclusion : As results of the study , the majority of students, parents, general teachers agreed needs of health education. Therefore, on the basis of this study, systematic and continuous health education is necessary. Additionally the establishment of independent health subject is required certainly.

2003년 국내 중증급성호흡기증후군 진료 현황 및 문제점 분석

이진수,김은실,정문현,백제중,정선화,안주희,최영화,이선희,고철우,김성범,김민자,박승철,기현균,송재훈,최상호,김양수,이상오,조용균,박영훈,정숙인,김연숙,이흥범,손창희,장성희,정희진,김우주 대한감염학회 2004 감염과 화학요법 Vol.36 No.3

목적 : 2002년 말 중국에서 SARS가 발생한 이후 국내에서도 2003년 10월까지 총 3명의 추정환자, 17명의 의심환자가 보고되었다. 향후 추가적인 SARS의 유행이 우려되는 상황에서, 그간의 SARS 환자 진료에 있어서의 실질적인 준비사항, 진료 현황 등에 대한 조사를 통해 문제점을 파악하여, 향후 더 나은 대비가 될 수 있도록 개선점을 제시하고자 하였다. 재료 및 방법 : SARS로 의심되는 환자를 진료 경험이 있는 병원의료진을 대상으로 2003년 10월에 설문조사를 실시하였다. 설문에는 SARS 환자 진료 시의 실질적인 조치, 진료 현황, 병실, 응급실 및 외래에서의 격리 시설과 준비사항, 보건당국의 관리와 지원에 관한 사항을 포함하였다. 결과 : 대상이 되는 22개 병원 중 17개(17/22, 77.2%) 병원이 설문에 응하였다. SARS 환자를 위한 격리실은 응급실, 외래, 일반병실 및 중환자실에서 각각 9개(9/17, 52.9%), 5개(5/17, 29.4%), 15개(15/16, 93.7%), 4개(4/16, 25%) 병원에서 음압처리가 되어있지 않은 일인실 혹은 다인실이 사용되었고, 1개(1/16, 6.3%) 병원에서만 일반병실에서 음압격리실이 운영되었다. 입원환자의 진찰 시 개인보호구의 착용은 거의 모든 의료기관에서 이루어졌다. 보건당국에서 SARS지정병원의 시설 등을 사전에 확인한 곳은 1곳(1/12, 8.3%)이였고, 14개 병원(14/15, 93.3%)에서는 보건당국에 의뢰한 검사결과를 통하 받지 못하였다. 결론 : 의료기관에서 SARS 환자용 격리실뿐만 아니라 기존의 격리실 설비 등이 미흡하였으며, 특히 중환자실 및 외래의 준비가 더욱 부족하였다. 보건당국의 의료기관에 대한 종합적인 지원이 부족하였고, 병원과의 원활한 연계가 잘 이루어지지 않았다. SARS 만이 아닌 격리를 필요로 하는 질환의 적절한 진료를 위해 향후 병원 시설의 정비와 정부차원에서의 보다 구체적이고 실질적인 대책마련이 필요하다. Background : There was an worldwide outbreak of the Severe Acute Respiratory Syndrome (SARS) originated from China in late 2002. During that period three cases of suspected SARS and 17 cases of probable SARS were reported in Korea. With the concerns about the reemergence of SARS-coV transmission, it is important to be prepared for any possibility. So, this study is aimed to analysis the past measures in managing SARS and propose the amendatory plans to improve the preparedness. Materials & Methods : Questionnaires were collected among clinicians with any experience in managing the probable or suspected SARS cases in Oct. 2003. 17 out of 22 hospitals responded to the questionnaire. The contents in the questionnaire were practical activities, personal equipments, response plans, isolation facilities in emergency centers, outpatient clinics, general wards and intensive care units, and relationship with the public health department. Results : The dedicated isolation rooms in emergency centers, outpatient clinics, general wards, and intensive care units were prepared in 9 (9/17, 52.9%), 5 (5/17, 29.4%), 15 (15/16, 93.7%), and 4 (4/16, 25.0%) hospitals, respectively. Except for one hospital that newly made negative pressure room for SARS, single or multi-bed rooms without airborne infection control were used in all the other hospitals. The personal precaution principles were kept quite well in general wards. Before the designation of SARS hospital by the public health department prior evalution to see if the hospital was suitable for managing SARS was conducted in only 1 (1/12, 8.3%) hospital. The results of laboratory diagnosis were reported back in 1 (1/15, 6.6%) hospital. Conclusions : The isolation facilities which can control airborne infection were almost deficient not only for SARS but also for other respiratory transmissible diseases. For the infection control of transmissible diseases including SARS, more investment is needed on medical facilities and comprehensive support from the public health department required.