• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.9
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• pp.2924-2932
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• 1996

As the environmental pollution can be greatly reduced and the waste heat can be also recovered through a combustion of municipal solid waste, the incineration begins to be highlighted recently in our country. But it is very difficult to be operated with constant combustion conditions for a long time as the domestic waste is composed of various components, contains a large percentage of water, and has a low heating value. Therefore, the cold flow test and partial hot flow test were conducted in the incinerator by use of injection angles of a secondary air affecting fluid flow as the first action to maintain the optimum combustion conditions. A model to a scale of 1:10 was designed and manufactured through the similarity of model and prototype flows. Velocities and temperatures were measured through the experiment. From the results, fluid flows of secondary air obtained from partial hot flow test correspond almost well with those of main flow obtained from cold flow test. Consequently, injection angles of secondary air are proved to affect main flow decisively.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.519-526
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• 2005

This paper presents computer simulation results for developing new type of SF$_{6}$ Circuit Breaker in terms of cold gas flow after small current interruption. This cold gas flows down a nozzle into the chamber of a circuit breaker. There are many difficult problems in analyzing the gas flow due to complex geometry, moving boundary, shock wave and so on. When predicting the dielectric capability of a gas circuit breaker after interruption, the gas pressure and density distributions due to the cold gas must be considered in addition to the electrical field imposed across the gas. A self-coded computational fluid dynamics (CFD) program is used for the simulation of cold gas flow in order to evaluate the electrical field characteristic across open contacts and transient characteristics of insulations after small current interruption.

• The Korean Journal of Nuclear Medicine
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• v.21 no.2
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• pp.183-190
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• 1987

In Raynaud's phenomenon, the authors measured finger blood flow after ice water exposure by analyzing the time activity curve of radionuclide angiography on both hands. The results were as follows: 1) The digital blood flow did not decrease after ice water exposure in normal subjects. 2) In the patients with Raynaud's phenomenon, there were two groups: the one had decreased digital blood flow after cold exposure, and the other had paradoxically increased digital blood flow after cold exposure. 3) There was no difference in the digital blood flow of hand in room temperature between the normal and the patients with reduced digital blood flow after cold exposure, but the digital blood flow of the hand in room temperature was markedly reduced in the patients with paradoxically increased flow after cold exposure. 4) In the static image the difference was not significant in comparision with the dynamic study, because it represents pooling of the blood in the vein rather than flow. 5) After the treatment with nifedipine, the digital blood flow increased. In conclusion, the radionuclide angiography was useful in measuring the digital blood flow in Raynaud's phenomenon, and further studies with various drugs is expected.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.181-185
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• 2010

The behavior of combustion-induced internal flow of SRM equipped with fin-slot grain and submerged nozzle is very complex and diverse. Cold air-flow test for 2D and 3D scale models of SRM has been done in order to specify the visualization method to analyze particular internal flow patterns such as roll-torque inducing flow. Swirl flow induced by asymmetric vortical tube also has been visualized through employing various light source and recording directions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.637-642
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• 2017

In this study, cold flow and combustion tests are conducted and analyzed to validate designed rocket engine head generating high temperature/pressure steam. At first, uni-injector was designed and manufactured, and cold flow test was conducted. Through this, differential pressure that can supply designed flow rate was confirmed. Also, Each injector's spray pattern were confirmed by patternator. Based on cold flow test results, we selected injectors among the candidates and arranged them on engine head, and cold flow and propellant spray tests were conducted. Finally, combustion test was carried out to analyze the flow rate, pressure, combustion efficiency. As a result, validation of rocket engine head for the development of the high temperature and high pressure steam generator has been completed.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1512-1516
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• 1994

FLIC(Fluid in cell) method has been used for analyzing a cold gas flow field in an interrupter of a circuit treater since 1970s. In this paper FLIC method is applied to calculation of a cold gas flow and then combined with the simple are analysis method in order to investigate the flow field characteristics in a puffer type interrupter rated at 145kV 40kA. The results for a cold gas flow agree with the experimental measurement well. The other results such as pressure rise, arc temperature, post-arc current and so forth am also reasonable and show the possibility that the combined program can be applied to the design of UHV interrupters.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.110-117
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• 2022

A chiller cooler absorbs the thermal energy of water to generate cold water and supplies the generated cold water to a cold water pipe buried in the wall of a small mobile modular house to greatly increase the cooling area. An attempt was made to reduce the required cooling time significantly. A small chiller cooler suitable for the cooling load of a small mobile modular house with an area less than 3.3 m² was employed. When cooling is done during summer using a chiller cooler installed outdoors, heat absorption energy loss occurs in the cold water pipe owing to the high temperature. To address this, a study was conducted to reduce the endothermic energy loss significantly. As the mass flow rate of the cold water flowing inside the cold water pipe increased, the temperature decrease gradient of the cold water increased. From the start of the cooling operation, the air temperature of the small mobile modular house decreased linearly in proportion to the operation time. Furthermore, the temperature of the air inside the small mobile modular house decreased in proportion to the increase in the flow of water inside the cold water pipe.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.2
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• pp.133-151
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• 2019

This study aims to analyze cold air characteristics in the watershed areas and to suggest strategies for utilizing them in urban ventilation corridor plans. For this purpose, the Jungnangcheon watershed and Uijeongbu-si in the northern part of Gyeonggi province, and Anyangcheon watershed as well as Yangjaecheon Tancheon watershed and Gwacheon-si in the southern part were selected as study areas. We used KALM (Kaltluftabflussmodell), a cold air simulation model developed in Germany and identified both the cold air flow and the height of cold air layer generated during 6 hours at night. Uijeongbu City is located on the main stream of the Jungnangcheon watershed, and the local cold air from the southern outskirts is an important part of Uijeongbu-si's overall ventilation corridor planning. In addition, the cold air generated in the vicinity of Mt. Sapae flows into the central business district near the city hall and plays a major role in regulating the thermal environment of the city. But, the cold air flows in the eastern part of Uijeongbu-si was not smoothly. The cold air flow generated in the east of Gwanak Mountain and in the west of Cheonggye Mountain was the most active in the northern part of Gwacheon-si. This flow is also a major ventilation corridor in Anyangcheon watershed as well as Yangjaecheon Tancheon watershed. But, the southern part where the cold air flow is not smooth is planed to be developed as 'Gwacheon Knowledge Information Town Public Housing District', so rapid development is expected in the future. Hence, it is suggested that an additional ventilation corridor plan should be established based on the detailed local wind flow analysis.

• Journal of Biosystems Engineering
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• v.33 no.6
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• pp.396-403
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• 2008

Because thermal non-uniformity of transported agricultural products is mainly affected by cooling air flow pattern in the cold transport equipment, the analysis and control of flowfield is key to optimization of cold transport equipment. The objectives of this study were to estimate the effects of geometric and operating parameters of cold container on the air flow and heat transfer, and find the optimum design parameters for the low temperature level and its uniformity in given cold container with CFD simulations. Existences of ducts, gaps between pallets and geometries of exit as geometric parameters and fan blowing velocity as operating parameter were investigated. CFD simulations were carried out with the FLUENT 6.2 code. The result showed that optimum design condition was bulk loading with no duct, wall exit and 8.0 m/s of fan blowing velocity.

• Journal of Power System Engineering
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• v.7 no.2
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• pp.17-22
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• 2003

As side-by-side refrigerators came into existence, there has been a growing concern about the free%ins-up of the vital equipment in a walk-in freezer. Due to a bad performance, customers are experiencing too much frustration. In order to minimize the freezing phenomena, the numerical simulation has been performed on the characteristics of cold air flow in a side-by-side refrigerator. The flow field has been simulated with a standard $k-\varepsilon$ turbulent model and a SIMPLE algorithm based on the finite volume method. Through the results of the analysis of the pattern of cold air flow, finally the shape of outlet for cold air flow was modified. The present model was compared with the modified model. The latter was better than the former in minimizing the freezing phenomena.