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>

Hepatic Cirrhosis Occurring in a Young Woodchuck(Marmota monax) Due to Vertical Transmission of Woodchuck Hepatitis Virus(WHV)

Kyu-shik Jeong,정원일,Jae-yong Chung,Mi-young An,Chae-yong Jung,Gyoung-jae Lee,Jong-soo Kang,Byeong-cheol Kang,Young-heun Jee,Bruce H Williams,Young-oh Kwon,Da-hee Jeong 대한수의학회 2003 Journal of Veterinary Science Vol.4 No.2

Cirrhosis Occurring in a Young Woodchuck (Marmota monax) Due to Vertical Transmission of Woodchuck Hepatitis Virus (WHV)Da-hee Jeong, Won-il Jeong, Jae-yong Chung, Mi-young An, Chae-yong Jung, Gyoung-jae Lee1, Jong-soo Kang1, Byeong-cheol Kang2, Young-heun Jee3, Bruce H Williams4, Young-oh Kwon5 and Kyu-shik Jeong*College of Veterinary Medicine, Kyungpook National University, Daegu 702-701, Korea1Shinwon Scientific Co., LTD, Research Institute, Suwon, Korea2Clinical Research Institute, Seoul National University, Seoul 110-744, Korea3College of Veterinary Medicine, Jeju National University, Jeju 690-756, Korea

남자 고등부 태권도 경기 내용 분석 : 발기술을 중심으로 Focused on Feet Technigues

권오륜,노영태,황영성 釜山大學校 附設 體育科學硏究所 1997 體育科學硏究所 論文集 Vol.13 No.-

This worker has wanted to make out various feet techinques and basic data for improving competitions by analyzing feet techniques frequencies, and effective piont scoring scale in High School Boys' national competitions. Through the study of practical examples, this worker has made these following conclusion: 1. The four different feet techniques were used at The National Olympics, The League of Middle High School Students, and The Pusan Preliminary Matches for the National Olympics in the following various frequencies ; Dolyechagi 222 times(52%), Nalaechagi 63 times(15%), Butchechagi 48 times(11%), and Dutchagi 49 times(11%). 2. An effective point scoring scale could be arranged like this : Dolychagi 45 points(55%), Nalaechagi 12 points(15%), Dutchagi 9 poins(11%), Butchechagi 6 paints(7.3%). 3. The various feet techniques and effective point scoring scale in Tae Kwon Do competitions. These conditions could be especially important for the favored winners. 4. Tae Kwon Do players should practice not only basic techniques but also various feet techniques in order to perform active and aggressive matches.

노화가 인체 중간엽 줄기세포로부터 조골세포로의 증식 및 분화에 미치는 영향

백기현,태현정,오기원,이원영,조정기,권순용,강무일,차봉연,이광우,손호영,강성구,김춘추 대한내분비학회 2003 Endocrinology and metabolism Vol.18 No.3

연구배경: 일반적으로 골다공증과 연관된 위험인자로는 연령, 폐경, 약물, 불충분한 칼슘섭취, 만성질환 및 운동부족 등이 있는데, 특히 노화가 진행할수록 골밀도가 감소하는 것은 잘 알려져 있다. 노화와 관련하여 진행되는 골소실은 조골세포 및 전구조골세포의 기능적 결핍에 의한 골형성의 감소가 주요한 요인으로 여겨지고 있다. 그 동안 연령이 조골모 세포의 양과 조골모 세포로부터 성숙조골세포로의 분화 및 증식에 미치는 영향에 대한 일부 보고들이 있었으나 아직 일치된 견해는 없는 형편이다. 방법: 다양한 연령의 사람으로부터 골수를 채취, 중간엽 줄기세포가 포함된 단핵세포를 분리한 후 조골세포로 분화하기 좋은 조건하에서 배양하였다. 대상군은다시 젊은군과 노령군으로 구분하여 다양한 변수를 비교 분석하였다. 일차배양에서는 CFU-F를 계수하여 골수내 중간엽 줄기세포의 수를 추산하였고, 칼슘측정을 통하여 기질의 무기화 정도를 비교하였다. 계대배양후 이차배양에서는 시기별로 알카리성 포스파타제 활성도를 측정하고 오스테오칼신 mRNA의 발현을 관찰하여 젊은군과 노령군 사이의 증식능 차이를 비교하였다. 또한 이차배양 시기별로 MTT 측정을 하여 양군간에 증식능 차이가 있는지 알아보았다. 결과: 1. 일차배양 15일째에 평균 CFU-F의 수는 젊은군에서 유의하게 많았다(젊은군 148.3±28.9, 노령군 54.3±9.1, p=0.02). CFU-F의 평균면적은 젊은군에서 넓은 경향을 보였으나 통계적으로 유의하지는 않았다. 2. 일차배양 17일 경과 후 양군간에 기질 칼슘 침착정도는 유의한 차이를 보이지 않았다(젊은군 103.6±50.6, 노령군: 114.0±56.5, p=NS). 3. 이차배양 10일째에 젊은군에서 알카리성 포스파타제 활성도가 고령군에 비해 유의하게 높았다(젊은군: 935.5±115.0 U/mg, 노령군: 578.4±115.7U/mg,p.0.05). 고령군에서는 시간 경과에 따른 변화가 미약했으며 전반적으로 알카리성 포스파타제의 활성도가 젊은군에 비해 낮았다. 4. 이차배양도중 오스테오칼신 mRNA의 발현은 배양시기별로 젊은군에 비해 고령군에서 더 낮은 경향을 관찰할 수 있었다. 5. 이차배양 10일과 15일에 젊은군에서 노령군보다세포증식이 유의하게 증가된 양상을 보였다(10앓 젊은군 0.73±0.05, 노령군 0.58±0.04, p=0.05, 15일; 젊은군 0.80±0.05, 노령군 0.70±0.03, p=0.05).결론: 이상의 연구에서 저자들은 노령군에서 젊은군보다 골수 내 중간엽줄기세포의 수가 적고, 노령군에서 유래한 전구조골세포의 성숙조골세포로의 증식 및 분화가 젊은군 보다 감소해 있는 것을 관찰할 수 있었다. Background: Osteoblasts originate from osteoprogenitor cells in bone marrow stroma, termed mesenchymal stem cells (MSCs) or bone marrow stromal cells. Each MSC forms colonies (colony forming units-fibroblasts [CFL-Fs]) when cultured ex vivo. There are some reports about the age-related changes of the number and osteogenic potential of osteoprogenitor cells, but any relationship has not been clearly established in humans. In this study, we counted MSCs using CFU-Fs count and examined the proliferative capacity and differentiation potential of osteoprogenitor cells. Finally, we analyzed how these parameters varied with donor age. Methods: Bone marrow was obtained from the iliac crest of young (n=6, 27.2±8.6 years old) and old (n= 10, 57.4k6.7 years old) healthy donors. Mononuclear cells, including MSCs, were isolated and cultured in osteogenic medium. In primary culture, we compared the colony-forming efficiency of MSCs between the two groups and determined the matrix calcification. When primary culture showed near confluence, the cells were subcultured. Alkaline phosphatase activity, osteocalcin expression by RT-PCR and proliferative potential by MTT assay were examined by the time course of secondary culture. Results: At the 15th day of primary culture, the mean number of CFU-Fs was significantly higher in the younger donors (young: 148.3±28.9, old: 54.3±9.1, p=0.02) and the mean size of CFL-Fs was also larger in the younger donors than the older donors. However, matrix calcification was not different between the two groups (young: 103.6±50.6, old: 114.0±56.5, p=NS). In secondary culture, alkaline phosphatase activities were significantly lower in the older donors. The younger donors showed peak alkaline phosphatase activity at day 10, while the older donors didn't showed a remarkable peak (young: 935.5±115.OU/mg, old: 578.4±115.7U/mg, p<0.05). Total cell number as a proliferative index increased progressively during the secondary culture and a significantly greater cell number was noted in the younger donors. Osteocalcin expression was generally upregulated in the younger donors, but this was not statistically significant. Conclusion: Our study shows that the number of osteoprogenitor cells is decreased during aging and that the proliferative capacity and differentiation potential of osteoprogenitor cells seem to be reduced during aging (J Kor SOC Endocrinol 18:296-305, 2003).

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>

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).

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.

신라 中古·中代期 상대등과 왕위계승

權英五 부산경남사학회 2003 역사와 경계 Vol.47 No.-

Sangdaedeung, an extraordinary rank one, instituted in A.D.531, resulted from the policy of King Peopheung who tried to bureaucratize the nobility for the centralism around king beginning with the establishment of Pyeongbu(兵部) or the office of the military. In Mid-ancient period of Silla, the principle that only a man from Sungkol, the highest caste, succeeded to the throne when a king had no heirs had been established. He had been legitimatized by ascending the throne in the form of Kukinchudae(國人推戴) and in such a process Sangdaedeung had played a leading role. Unlike the existing studies, the rebellion of Sangdaedeung Pidam, in the late years of King Seondeok was not to claime the legitimacy of Sangdaedeung's succession rights, but to protest against the regular succession to the throne of Sungkol in the circumstance that Seungman(later King Chindeok) had heirdom. And It is reasonable that the subjects' request of Regent to Alcheon after the death of King Chindeok is considered for Alcheon to play a ritual role for the installation to the throne of Kim Chunchu, rather than to succeed to the throne. The Prince system had established itself by the beginning of the Middle period. It is even said that it was the main feature of the royal family in the Middle period. I think that its establishment was related to the fact that King Muyeol who did not come from Sunggol had ascended to the throne as Donggung(東官). Also, there are no documents that Sangdaedeung reclaimed the succession rights against ascending the throne of young Kings, younger brother(同母弟) in the Middle period. The King Muyeol's appointment of Kim Yushin who was from the lineage of Kaya to Sangdaedeung demonstrates that the position of Sangdaedeung was an office appointed by King. Thus, Sangdaedeung in the Middle period must be considered as the position which installed heirs to the throne at the noble assembly, not the one that could claim the succession rights. Consequently, It had taken the bureaucratic feature corresponding to the reinforcement of royal power.

소득작물 전후작지 적응 극단기성 벼 ‘중모 1032’

손영보,이종희,조준현,이지윤,오성환,송유천,박동수,박노봉,김상열,여운상,남민희,권영업 忠北大學校 農業科學硏究所 2015 農業科學硏究 Vol.31 No.2

환기시스템의 효율 향상을 위한 후드 내 유해물질 포착속도 개선에 관한 연구

오율권,김영선,박경수 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1

Most of the hood maximize on capture velocity concentrate in inhalation capacity of harmful materials on hood of center. But, decrease generally ventilation system efficiency because, the edge of hood decrease capture velocity of harmful materials. So, development on the gas-guidance-device for increase of capture velocity of harmful materials in hood increase generally ventilation system efficiency. In this study, flow in hood doing visibility after numerical analysis using the Phoenics 3.1 on commercial code of heat and fluid using finite volume method. And, boundary conditions establish the same condition as work space that it is temperature is 20 degrees, pressure in 1 atm, velocity in duct is 6.85m/s, diameter is 400mm. Also, gas-guidance-device draw optimum shape as a result comparison and analysis as being numerical analysis of variety shape. As the result of study, compare hood have gas-guidance-device with hood have no gas-guidance-device identify increase on harmful materials capture velocity. Also, gas-guidance-device identify best inhalation efficiency in hood when it is 125mm wide and a ratio of 4 to 6 on side. So, safety of worker and work environment improvement expect helped as a result remove effective on harmful materials in work space and cut down on expenses of occurrence when the inhalation volume again design for efficiency improvement of ventilation system.