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이성광(Sung-Gwang Lee),박한준(Han June Park),이인재(Injae Lee),남예빈(Yebin Nam),황원태(Wontae Hwang) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
As the critical dimension of semiconductors is miniaturized, the semiconductor fabrication process requires extreme purity and cleanliness, and many semiconductor facilities perform the process after creating a vacuum environment. Precursor gases used during the process make patterns by repeating deposition and etching through wafer surface reaction. In order to increase the production yield of circular wafers, it is essential to predict the behavior of process gases in a vacuum environment. Although computational fluid dynamics (CFD) is being performed to predict the airflow, there are very few studies that visualize and analyze the airflow through an experiment in a vacuum environment due to the difficulty of measuring the airflow. Therefore, there is a limit to verifying the CFD results. This study visualizes a supersonic round jet airflow in a vacuum environment in a 2D plane where the absolute pressure is lowered to 1 Torr. Using PIV, the structure of the jet, turbulent kinetic energy (TKE), and vorticity are analyzed by measuring the flow velocity of the jet. In addition, the location, size, and structure of the shockwave were analyzed using shadowgraphy. Through this study, we intend to provide an experimental basis for visualization of airflow in a vacuum environment.
이성한(Sung-Han Lee) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
After the Fukushima accidents, it has been one of the key issues to keep the integrity of the containment during a severe accident. In Korea, adding containment filtered venting system (CFVS) installed as one of the Fukushima actions to an existing nuclear power plant has been suggested as one approach to mitigate the effects of a severe accident such as Loss of Coolant Accident (LOCA), Steam Generator Tube Rupture (SGTR) and Station Blackout (SBO), etc. CFVS was first installed at Wolsong unit 1 which is the CANDU type reactor. CFVS which does not require an external source of power is used to prevent loss of containment integrity as a result of over-pressurization and relieve containment pressure for the conditions that could be present in a severe accident, and provide reliable venting function for containment pressure control. CFVS is designed to open and to close isolation valves passively by an operator. CFVS is operated when the containment pressure exceeds the design pressure (225 ㎪(a)) and is closed when the containment pressure decreases below 150 ㎪(a) [1]. In addition, the key function of CFVS is to reduce the radioactive material releasing from the containment to the environment through a high-efficiency scrubber and filters. That enables pressure to be reduced using a filtered system that retains and recirculates airborne radioactivity within containment and operates passively without the need for a power supply. Compared with the pressurized water reactor (PWR) containment, the containment of CANDU reactor has lower resistance to internal pressure increase because they have no steel liner inside and design pressure itself is lower. In this regard, the analysis of the thermal-hydraulics behavior of CANDU reactor during a severe accident is needed to evaluate the containment integrity. Therefore, the aim of this study is to evaluate the depressurization performance of Wolsong unit1 considering CFVS operation during SBO using the MELCOR code developed at Sandia National Laboratories (SNL) for the U.S. Nuclear Regulatory Commission (NRC). In addition, in order to evaluate the effects of the CFVS performance, a sensitivity study depending on the different venting area of the CFVS was conducted. Finally, an analysis of the CFVS performance to evaluate the effects of filtering and scrubbing of radioactive material during a severe accident is important. The effects of filtration efficiencies for the filters of CFVS is evaluated and then a sensitivity study depending on decontamination factor (DF) of the filters was carried out.
선천성(先天性) 심장병(心臟病)의 개심술(開心術) -6례(例) 수술경험(手術經驗) -
이성행,이성구,한승세,이길노,김송명,이광숙,이종국,Lee, Sung Haing,Lee, Sung Koo,Han, Sung Sae,Lee, Kihl Rho,Kim, Song Myung,Lee, Kwang Sook,Lee, Chong Kook 대한흉부심장혈관외과학회 1976 Journal of Chest Surgery (J Chest Surg) Vol.9 No.2
Six cases of congenital heart disease were operated on by means of cardiopulmonary bypass between December, 1975 and April, 1976. Two cases of ventricular septal defects (VSD), two cases of VSD, associated with ruptured aneurysm of sinus Valsalva, two cases of atrial septal defects (ASD) and one case of pulmonic stenosis with patent ductus arteriosus were operated. Sarns roller pumps and Bentley Temptrol oxygenators were used for extracorporeal circulation. Pump oxygenator was primed with Ringer's lactate solution, 5% dextrose in water, mannitol, and ACD blood. Flow rate ranged from 2.0 to $2.4L/M^2/min$. Bicarbonate was added to the oxygenator with estimated amount as 15 mEq/L/hr. Venous catheters were introduced into superior and inferior vena cava, and oxygenated blood was returned to the body through aortic cannula inserted into ascending aorta. Moderate hypothermia ($30^{\circ}C$) was induced by core cooling. Aorta was cross clamped for 15 minutes and released for 3 minutes, and repeated clamping when necessary. Atrial and ventricular septal efects were closed by direct sutures. Aneurysms of sinus Valsalva ruptured into the right ventricle were repaired through right ventriculotomy by d:rect closure with Dacron patch reinforcement. Cardiopulmonary bypass time varied from 66 to 209 minutes, and aorta cross clamping time ranged from 13 to 56 minutes. Postoperative bleeding was minimal except one case who needed for evacuation of substernal hematoma. Intra- and postoperative urinary output was satisfactory. Acid-base balance, partial pressure of $O_2$, electrolytes, and hematological changes during intra- and post-perfusion period remained at the acceptable ranges. No mortality was experienced.
중수로 원전의 발전소정전사고시 격납건물여과배기설비를 고려한 열수력거동 분석
이성한(Sung-Han Lee),김진혁(Jin-Hyuck Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.열공학 No.-
After the Fukushima accidents, it has been one of the key issues to keep the integrity of the containment under a severe accident. In 2012, containment filtered venting system (CFVS) first installed at Wolsong unit 1 in Korea can be used to depressurizethe containment during a severe accident such as Station Blackout (SBO). In addition, the key function of CFVS is to reduce the radioactive material releasing from the containment to the environment through a high-efficiency scrubber and filters. CFVS is operated when the containment pressure exceeds the design pressure (124 kPa(g)) of the containment building, the operator opens CFVS isolation valves. Then steam and air in the containment flows out to the environment through the CFVS and the containment pressure decreases below 50 kPa(g). The SBO accident is chosen to analyze the depressurization performance of Wolsong unit 1 in consideration of the CFVS operation. The thermal-hydraulic behavior in containment of Wolsong unit 1 was evaluated using the MELCOR code developed at Sandia National Laboratories (SNL) for the U.S. Nuclear Regulatory Commission (NRC). The geometry of Wolsong unit 1 was modeled with one cell divided into 4 control volumes such as containment, CFVS, CFVS building and environment, and the simulations were run up to 260,000 sec (72 hrs). Also, in order to carry out a sensitivity study, the flow path area as a variable parameter is chosen as 0.0065 ㎡, where this area indicates a venting size of the CFVS for 8 inch, 16 inch, 16 inch and 32 inch, respectively. The results show that the containment pressure is repeatedly rising and falling but it decreases gradually after 46 hrs in case of operating CFVS. On the other hand, the pressure continuously increases and then exceeds the containment failure pressure (427 kPa(a)) at 45.7 hrs without operating CFVS. That is, the containment pressure is considerably decreased and the integrity of the containment could be maintained when CFVS was operated. Therefore, it seems that CFVS has the capacity to keep the containment pressure below the design pressure during SBO. In addition, there are large differences in the containment pressure depending on venting size of CFVS. We found that the decreasing rate of the pressure in the containment and water level in CFVS depends on the venting size of CFVS. In the future, analyses of aerosols, fission product, and radioactive material behavior in containment and remove performance of radionuclide in CFVS are planning to be conducted.
확장/축소 배열의 마이크로 채널의 관성력을 이용한 적혈구와 순환 종양 세포 분리 연구
이성한(Sung Han Lee),Thapa Mukesh,박민규(Min Gyu Park),채혜송(Hyeon Song Chae),허윤석(Y.S. Heo) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Recently, particle separation studies have been conducted in micro systems. Particularly, the method of separating particles by a hydrodynamic method requires no additional external force. It is also possible to separate cells from microfluidics systems using cells instead of particles. We have conducted a study to isolate circulating tumor cells from red blood cells. Because circulating tumor cells are present in very small amounts compared to blood cells, the enrichment step is required for effective detection. We designed expansion/contraction array microchannel, which separates circulating tumor cells(MCF-7) from red blood cells by inertial force. This microchannels have experimentally proven that cells can be separated with high throughput and high efficiency.