• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2126-2135
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• 1992

In order to prevent the decay heat removal system from failure due to air entrainment or free surface vortex in the piping system, a set of simulating experiments for the midloop operation of nuclear power plant was performed. Through these experiments, a relation between the dimensionless numbers, such as submergence H/d, froude number, reynolds number, was found. However, the effect of reynolds number was negligible for the operation conditions of Nuclear power plant. It was also found that the perturbation of the system by the disturbance such as pump start, valve operation, etc., has a strong effect on the free surface vortex. Furthermore, from a view point of reactor safery, a modified inlet device of reducer type is strongly recommendable for the prevention of air entrainment.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.353-358
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• 2001

Turbo-charging or Super-charging has been used to boost engine power for Gasoline Engine and Diesel Engine came to the world at the beginning of $20^{th}$ century. So far Turbo-Charger has enjoyed a high reputation in the charging filed for its technical advantages such as no demand of operation power from engine and an excellent charging effect in the event of a static operation at mid- and high engine speed. A mechanically driven Super-Charger, however, is now emerging in order to meet demands of the age of speed such as high engine power for a quick change of the driving mode - high engine torque even at low engine speed. Since Super-Charger needs driving power from engine, it cannot improve its relatively higher fuel consumption against that of Turbo-Charger. This negative point is still an obstacle to the wide use of Super-Charger. Super-Charger using Screw-type compressor which has already had a considerable base in air compressor market will fulfill this purpose of improving fuel consumption by minimizing operation power owing to no charging at idling or partially loading driving. This study aims to develop power control concept to achieve this minimization of operation power.

• Journal of ILASS-Korea
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• v.9 no.1
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• pp.37-42
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• 2004

In a port fuel injection system of engine, a large part of fuel injected into an intake port adheres on its wall and inlet valve. Consequently, the wall impinging spray interaction might occur the generation of several harmful phenomena. There are uncontrollable mixture formation, an accidental backfire and unburned hydrocarbons. Therefore, it is important to analyze the fuel behavior during the spray-wall interaction. In this study, splash characteristics of impingement and reflecting or scattering behavior of droplets of fuel injected from EFI nozzle were studied experimentally. A test fuel used is LAWS and its physical characteristics are similar to the conventional gasoline except for the ignition point. Since the liquid film formed immediately after impinging on an impingement plate is unstable, it is easy to cause secondary disintegration. In addition, when the intermittently impingement on the impingement plate with LAWS, the splash ratio is around 0.6. If an injection period becomes longer, liquid film will become thick and the splash ratio will fall bout 10 percent. On the other hand, when the injection period of an intermittent spray is long, the same time lapse as a continuous spray is shown.

• Journal of Chest Surgery
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• v.22 no.2
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• pp.348-356
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• 1989

Seventeen patients of pulmonary atresia with intact ventricular septum were underwent operation during 4.8years period from Jan. 1983 to Aug. 1988 at Seoul National university Hospital. The patients were composed of 8 males and 9 females, aging 1day to 2.5 years [mean 88 days]. We classified pulmonary atresia according to right ventricular morphology; those with tripartite ventricles in 12, those with no trabecular portion to the cavity in 0, and those with inlet portion only in 5. The tripartite approach to right ventricular morphology is helpful in selecting the type of initial palliative procedures. Palliative procedures were as follows; pulmonary valvotomy in 5 with 3 early survivors, mod B-T shunt in 4 with 3 early survivors, and palliative right ventricular outflow tract reconstruction in 4 with 1 early survivor. Effective preliminary palliation of pulmonary atresia are pulmonary valvotomy or palliative right ventricular outflow tract reconstruction in those with tripartite right ventricle, and modified Blalock-Taussig shunt in those with no infundibular portion. The approach to definitive repair is based primarily on the actual size of the tricuspid annulus and the right ventricular cavity. Definitive repair was as follows: definitive right ventricular outflow tract reconstruction in 4 with all survivors and mod. Fontan operation in 2 with one survivors. Right ventricular outflow tract reconstruction can be done as complete repair for patients who had adequate tricuspid annulus and right ventricular cavitary size and mod. Fontan operation for patients who severely hypoplastic tricuspid valve annulus or small right ventricular cavity.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.782-787
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• 2008

The Kalina cycle simulation study was carried out for a preliminary design of a geothermal power generation system. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The simulation results show that the power generation efficiency over 10% is expected when a heat source and sink inlet temperatures are $100^{\circ}C$ and $10^{\circ}C$ respectively.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.93-98
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• 2010

본 연구에서는, 반도체, LCD 공정에서 금속막을 증착하기 위하여 PECVD장비에 화재, 폭발 위험성과 독성을 가진 Silane가스를 사용하게 되는 장비인 gas cabinet, pipeline, VMB(Valve manifold box), MFC(mass flow controller)장비 등, 전반적인 시스템에 대하여 영국 HES의 ALARP개념을 도입하여 위험성 평가를 실시하여 문제점을 도출하고 대책을 강구 하는데 목적이 있고, 여러 가지 문제점중 절대적으로 수용 할 수 없는 Critical Risk로는 Gas Cylinder를 사용하여 Silane을 공급하고자 할 때에는 필히 Gas Cabinet을 사용하여 공급하여야 하고, Tube Trailer를 사용하여 공급하고자 할 때에는 필수적으로 Purge System을 갖추어 공급하여야 한다. 선택적으로 수용할 수 있는 High, Medium Risk로는 Gas Cylinder 또는 Tube Trailer를 사용하여 Silane을 공급하고자 할 때는 Inlet 부분에 RFO(Resticted Flow Orifice)를 설치하여 사용하고 Gas Supply Room에는 CO2소화설비를 적용하지 말고 Water Mist등 물 분무설비를 적용하여야한다.

• Nuclear Engineering and Technology
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• v.24 no.3
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• pp.311-318
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• 1992

During mid-loop operation of Nuclear Power Plant, to prevent the Decay Heat Removal System (DHRS) from failure due to air entrainment of free surface vortex in the piping system, a set of simulating experiments was performed. Through these experiments, a relation between the non-dimensionalized numbers, such as H/d, Froude number, Reynolds number, was found. It was also found that the perturbation of the system by the disturbance such as pump start, valve operation, etc., has a strong effect on the free surface vortex. Furthermore, from viewpoint of reactor safety, a modified inlet device which is reducer type is strongly recommended for the prevention of air entrainment into DHRS.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.418-423
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• 2014

Small hydropower has been considered as a solution to resolve the problem of exhaustion of fossil fuel and industrial pollution. In this study, we developed and tested a Cross-Flow Turbine with two guide vanes to optimize the small hydropower for the site condition with large fluctuation of head and flow rate. Furthermore, in the condition of constant inlet head, CFD analysis was carried out to analyze the effect of air suction and valve position on the performance characteristics. The results showed that the air suction can minimize the hydraulic loss caused by the Recirculation flow in the runner passage and flow impact on main shaft so that it can increase the turbine efficiency and output power.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.151-156
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• 2008

Water flow characteristics of an apartment complex consisting of 12 buildings and 635 units in total have been investigated numerically. The complex incorporates two zone booster pump water supply system, and some units have pressure reducing valves in them. Input data to a commercial code Flowmaster7 include survey results on the water usage for the last three years, dimension of the water supply system and its operation condition, etc. Calculated static pressures at the inlet of all units are compared with their design and measured counterparts, and they agree quite well with each other. Then, the pressure distributions and volumetric flow rates at all 635 units are estimated. Flow balancing is also attempted by varying the ratio of angle valve of each unit to improve the non-uniformity of flows.

• The KSFM Journal of Fluid Machinery
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• v.7 no.5 s.26
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• pp.29-35
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• 2004

The turbine efficiency is an important factor in power plant, and accurate evaluation of steam turbine performance is the key issue in turbo machinery industry. The difficulty of evaluating the steam turbine performance due to its high steam temperature and pressure environment makes the most steam turbine tests to be replaced by air similarity test. This paper presents how to decide the similarity conditions of the steam turbine test and describes its limitations and assumptions. The test facility was developed and arranged to conduct an air similarity turbine performance test with various inlet pressure, temperature and mass flow rate. The eddy-current type dynamometer measures the turbine-generated shaft power and controls the rotating speed. Pressure ratio of turbine can be controled by back pressure control valve. To verify its test results, uncertainty analysis was performed and relative uncertainty of turbine efficiency was obtained.