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>

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.

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.

배연탈황흡수제의 탈황성능에 관한 연구

양정선,김선근,오의경 중앙대학교 생산공학연구소 1995 생산공학연구소 논문집 Vol.4 No.2

배연 탈황 흡수제의 특성을 sand-bad 반응기를 이용하여 살피었다. 흡수제, 공정변수, 그리고 첨가제를 바꾸어 가며 기상에서의 탈황율을 비교하였다. 그리고 이 결과를 SEM, EDX, XRD, TGA, BET 등으로 탈황 전후의 흡수제 분말을 관찰하고 분석하여 검토하였다. 탈황율은 탈황제의 흡습성, 표면적, pore 구조 변화 등에 크게 의존하였다. 특히 Ca(OH)₂의 경우 흡수제의 pore 막힘 현상을 관찰하였으며 습도 및 첨가제의 효과가 이와 직접 연관이 있음을 알았다. Characteristics of sorbents for flue gas desulfurization has been investigated in sand-bed reactor. SO₂removal efficiency in gas phase was compared for the various sorbents, process variables and additives. The results have been discussed by observing and analyzing the sorbent particles before and after sulfation with SEM, EDX, XRD, TGA and BET. The SO₂ removal efficiency of the sorbents was affected by their hygroscopicity, surface area and pore-structure change during the reaction. In case of Ca(OH)₂, pore plugging was observed, and humidity of the gas and addition of the additives were directly related with the pore plugging.

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.

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 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.

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.

Flavobacterium odoratum의 TOL 플라스미드를 전달받은 광합성세균으로부터의 수소 생성

오순옥,조인선,이희경,민경희 숙명여자대학교 자연과학연구소 1991 자연과학논문집 Vol.- No.3

Flavobacterium odoratum SUB53의 TOL 플라스미드의 크기는 83 Md 이었으며 TOL 플라스미드에 의한 m-toluate의 최고분해농도는 5 mM이었다. Rhodopseudomonas sphaeroides KCTC1425의 수소생성은 nitrogenase의 활성과 비례하였으며 30 mM malate acid와 질소원으로서 7mM glutamate의 최적농도에서 최고의 수소생성을 보여 주었다. 한편, 0.3mM NH ion에 의해 nitrogenase의 활성이 저해되어 수소 생성이 현저히 감소하였다. F. odoratum SUB53과 Pseudomonas putida mt-2의 TOL 플라스미드는 R. sphaeroides에로의 접합시 수용세포의 대수증식기에서 10시간-15시간 동안에 최적이었으며 helper plasmid pRK2013에 의해 접합능이 증가하였다. Transconjugants인 R. sphaeroides C1(TOL SUB53)과 C2 (TOL mt-2)의 catechol-1,2-oxygenase(C-1,2-O)와 catechol-2,3-oxygenase(C-2,3-O)의 활성을 비교 검토한 결과 C-2,3-O 유전자를 code하는 유전인자는 TOL 플라스미드 위에 있으며, C-1,2-O 유전자의 위치는 chromosome 위에 있는 것으로 사료된다. 전자 공여체로서, m-Toluate는 R. sphaeroides C1과 C2의 TOL 플라스미드에 의하여 분해되어 수소를 생성함을 알 수 있었다. 이 결과는 TOL플라스미드에 의하여 m-toluate가 일차적으로 분해되고 생성된 이차산물로 부터 광선하에서 수소를 생성하는 것으로 추정된다. TOL plsmid size of Flavobacterium odoratum SUB53 was estimated as 83 Md and the optimum concentration of m-toluate degradation by TOL plasmid was 5 mM. H₂ production by Rhodopseudomonas sphaeroides KCTC1425 was largely dependent on nitrogenase activity and showed the highest at 30 mM malate with 7mM glutamate as nitrogen source. Nitrogenase activities were inhibited by 0.3mM NH ions, to be appeared the decrease of H₂ production. Conjugation of TOL plasmids from F. odoratum SUB53 and Pseudomonas putida mt-2 to R. sphaeroides showed the optimum at the exponential stage of recipient cells in presence of helper plasmid pRK2013. According to the investigation of catechol-1,2-oxygenase(C-1,2-O) and catechol-2,3-oxygenase (C-2,3-O) activities of R. sphaeroides C1 (TOL SUB53) and C2 (TOL mt-2), the gene for C-2,3-O is located on TOL plasmid and gene for C-1,2-O on the chromosome of R. sphaeroides. m-Toluate was biodegraded by TOL plasmid in R. sphaeroides C1 and C2, presumably to be produced H₂ gas from the secondary metabolites of m-toluate.

주거단지 외부공간의 친환경성 평가에 관한 연구 : 서울 신시가지와 신도시의 공공주거단지를 중심으로 Focused on the Case of Public Housing Estates in Seoul and New Towns

오수호,장선영,김석경,이규인 대한건축학회 2004 대한건축학회논문집 Vol.20 No.6

This study aims at assessing the status of environment-friendly outdoor spaces in housing estates. For this purpose, 62 housing estates were selected : 28 housing estates from 3 new residential districts of Gaepo, Mockdong, and Sanggae in Seoul, and 34 housing estates from 3 new towns of Gwacheon, Bundang, and Joongdong around Seoul. As an assessment tool, the indices and standard from 'Land Use and Transportation field' and 'Ecological Environment field' of 'Green Building Certification' were used. The result of evaluation was that the quality of outdoor environment in Gwacheon was very high, and the next one was Bundang, Gaepo, Sanggae, Mockdong, and Joongdong in order. In 'Land Use and Transportation field', many housing estates in Mockdong got high scores, and in 'Ecological Environment field', Gwacheon made a good score.