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x mol% 칼시아-안정화 지르코니아 나노분말의 수열합성 및 구조적 특성평가
류제혁,문정인,박연경,송정환,김택남,Ryu, Je-Hyeok,Moon, Jung-In,Park, Yeon-Kyung,Nguyen, Tuan Dung,Song, Jeong-Hwan,Kim, Taik-Nam 한국재료학회 2012 한국재료학회지 Vol.22 No.5
Pure zirconia and $x$ mol% calcia partially stabilized zirconia ($x$ = 1.5, 3, and 8) nanopowders were synthesized by hydrothermal method with various reaction temperatures for 24 hrs. The precipitated precursor of pure zirconia and $x$ mol% calcia doped zirconia was prepared by adding $NH_4OH$ to starting solutions; resulting sample was then put into an autoclave reactor. The optimal experimental conditions, such as reaction temperatures and times and amounts of stabilizer CaO, were carefully studied. The synthesized $ZrO_2$ and $x$ mol% CaO-$ZrO_2$ ($x$ = 1.5, 3, and 8) powders were characterized by XRD, SEM, TG-DTA, and Raman spectroscopy. When the hydrothermal temperature was as low as $160^{\circ}C$, pure $ZrO_2$ and $x$ mol% CaO-$ZrO_2$ ($x$ = 1.5 and 3) powders were identified as a mixture of monoclinic and tetragonal phases. However, a stable tetragonal phase of zirconia was observed in the 8 mol% calcia doped zirconia nanopowder at hydrothermal temperature above $160^{\circ}C$. To observe the phase transition, the 3 mol% CaO-$ZrO_2$ and 8 mol% CaO-$ZrO_2$ nanopowders were heat treated from 600 to $1000^{\circ}C$ for 2h. The 3 mol% CaO-$ZrO_2$ heat treated at above $1000^{\circ}C$ was found to undergo a complete phase transition from mixture phase to monoclinic phase. However, the 8 mol% calcia doped zirconia appeared in the stable tetragonal phase after heat treatment. The result of this study therefore should be considered as the preparation of 8 mol% CaO-$ZrO_2$ nanopowders via the hydrothermal method.
류향진 ( Hyang Jin Ryu ),유승흠 ( Seung Hum Yu ),박은철 ( Eun Cheol Park ),김정인 ( Jung In Kim ),손태용 ( Tae Yong Sohn ) 한국병원경영학회 2006 병원경영학회지 Vol.11 No.3
This study aims to deal with hospital staff`s recognition on the opening of the medical services market, their attitude to the opening-agreement and disagreement, and their intention to use a foreign hospital or to consult its doctors again. It was conducted for 450 employees of one university hospital located in Gyeonggi Province, Korea with systemized questionnaires. The main results of this study are as follows: First, Medical technicians showed the highest level recognition on the opening of the medical services market. Second, the percentage of agreement to the opening was the highest for medical technicians and lowest for doctors while that of agreement was the highest for doctors and lowest for nurses. For residents, among doctors, the percentage of disagreement was the lower than that of agreement. Third, the intention to use a foreign hospital and to consult its doctor again was the lowest for medical engineers and the highest for doctors. Fourth, the most urgent task for local hospitals to accomplish in response to the opening was the improvement of the diagnosis and treatment technologies for nurses, and the improvement of the service provided by the hospital staff for the others. For doctors, in particular, the improvement of the diagnosis and treatment technologies was just the fourth urgent task. In conclusion, the result varies to the type of occupation. Apparent difference was found for doctors, in particular, that seem to be directly affected by the opening of medical services market. Local hospitals and doctors, therefore, should make efforts together to improve the diagnosis and treatment technologies. All the hospital employees of every type of occupation, meanwhile, need to prepare for the opening with medical service of improved quality.
한근희,오동진,류정인,진경태,Han, Keun-Hee,Oh, Dong-Jin,Ryu, Jung-In,Jin, Gyoung-Tae 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.5
The characteristics of combustion and of emissions in pressurized fluidized bed combustor are investigated. The pressure of the combustor is fixed at 6 atm, and the combustion temperatures are set to 850, 900, and $950^{\circ}C$. The gas velocities are 0.9, 1.1, and 1.3 m/s. The excess air ratio is varied from 5 to 35%. The coal used in the experiment is Shenhwa coal in China. All experiments are executed at 2m bed height. Consequently, NOx & $N_2O$ concentration in the flue gas is increased with incresing excess air ratio but $SO_2$ concentration is decreased with incresing excess air ratio. CO concentration is maintained below 100ppm at over 15% of excess air ratio.
한근희(Keun-Hee Han),류정인(Jung-In Ryu),선도원(Dowon Shun),진경태(Gyoung-Tae Jin),손재익(Jae-Ek Son) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.11
가압유동층연소로(bed dia. 0.17m, freeboard dia. 0.25, total height 5m)에서 국내무연탄을 연소시켜 이에 대한 연소 및 배가스특성을 고찰하였다. 실험은 압력(2~6atm), 유동층온도(850~950℃), 과잉공기(10, 20, 30%)등이 연소효율과 열전달계수에 미치는 영향을 규명하였고, 그리고 탈황을 위한 Ca/S몰비 (0.8~4.8)가 배가스특성에 미치는 영향을 고찰하였다. 결과적으로, 본 연구의 실험범위에서 연소효율은 80~99%를 보였고, 연소온도, 압력 그리고 과잉공기가 증가할수록 증가하였다. 열전달계수는 223~571W/㎡K를 보였고, 연소온도와 압력 이 증가할수록 증가하였으나, 과잉공기가 증가하면 감소하는 것으로 나타났다. 또 배가스중의 SO₂는 압력, Ca/S몰비가 증가함에 따라 감소하였으며, NOx는 압력의 증가에 따라 감소하였고, N₂O와 CO는 연소온도와 압력이 증가함에 따라 감소하였다.
저 신장율 대향류 확산화염에서 화염 특성에 관한 버너 간격 효과
윤진한(Jin-Han Yun),길상인(Sang-In Keel),황동진(Dong-Jin Hwang),최윤진(Yun-Jin Choi),류정인(Jung-In Ryu),박정(Jeong Park) 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-
Experimental study is conducted to identify the existence of a shrinking flame disk and to clarify its flame characteristics through the inspection of critical mole fraction at flame extinction and edge flame oscillation at low strain rate flames. Experiments are made as varying global strain rate, velocity ratio, and burner distance. The transition from a shrinking flame disk to a flame hole is verified through gradient measurements of maximum flame temperature. The evidence of edge flame oscillation in flame disk is also provided through numerical simulation in microgravity. It is found at low strain rate flame disks in normal gravity that buoyancy effects are importantly contributing to lateral heat loss to burner rim, and is proven through critical mole fraction at flame extinction, edge flame oscillation, and measurements of flame temperature gradient along flame disk surface.
저 신장율 대향류 확산화염에서 화염 특성에 관한 배너 간격 효과
윤진한(Jin-Han Yun),길상인(Sang-In Keel),황동진(Dong-Jin Hwang),최윤진(Yun-Jin Choi),류정인(Jung-In Ryu),박정(Jeong Park) 한국연소학회 2008 한국연소학회지 Vol.13 No.4
Experimental study is conducted to identify the existence of a shrinking flame disk and to clarify its flame characteristics through the inspection of critical mole fraction at flame extinction and edge flame oscillation at low strain rate flames. Experiments are made as varying global strain rate, velocity ratio, and burner distance. The transition from a shrinking flame disk to a flame hole is verified through gradient measurements of maximum flame temperature. The evidence of edge flame oscillation in flame disk is also provided through numerical simulation in microgravity. It is found at low strain rate flame disks in normal gravity that buoyancy effects are importantly contributing to lateral heat loss to burner rim, and is proven through critical mole fraction at flame extinction, edge flame oscillation, and measurements of flame temperature gradient along flame disk surface.
초음파 에너지 부가 저 점도 바이오디젤 혼합연료의 미립화 특성에 관한 연구
송용식 ( Yong Seek Song ),김용철 ( Yong Cheol Kim ),류정인 ( Jung In Ryu ) 한국분무공학회 2004 한국액체미립화학회지 Vol.9 No.3
N/A This experiment was undertaken to investigate the atomization characteristics of the low viscosity biodiesel blended fuel and ultrasonic energy added one. Test fuels were conventional diesel fuel and biodiesel fuel. We compared to the characteristics of viscosity and surface tension, SMD between low viscosity biodiesel blended fuel and ultrasonic energy added one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension was measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy added situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than that of the conventional situation.
분체공학 , 유동층 , 고분자 , 재료 ( 무기 , 유기 ) : 가압유동층 연소로에서 무연탄의 연소특성
한근희(Keun Hee Han),강석환(Suk Hwan Kang),류정인(Jung In Ryu),진경태(Gyoung Tae Jin) 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.5
The combustion and emissions characteristics of the domestic anthracite coal containing 58.25% carbon and 0.34% sulfur was investigated in pressurized fluidized bed combustor(PFBC), 0.17 m bed I.D.×2 m height tapered bed and 0.25 m I.D.×3 m height freeboard. The pressure of the combustor was constantly maintained at 6 atm, and the combustion temperatures are varied from 850℃ to 950℃. Also the air velocity was changed from 0.9 to 1.3 m/s. Consequently, combustion efficiency and NO_χ concentration in the flue gas with increasing combustion temperature from 850℃ to 950℃ were increased in the ranges 93-99.5% and 33-70 ppm respectively. But N₂O concentration is obtained less then 20 ppm. SO₂ concentration increasing bed temperature from 850℃ to 950℃ in the flue gas was increased.