• Journal of Astronomy and Space Sciences
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• v.39 no.3
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• pp.79-86
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• 2022

Thermospheric wind observations from high to mid latitudes are compared with the newly developed Multiscale Atmosphere Geospace Environment (MAGE) model for the Nov 3-4 geomagnetic storm. The observation and simulation comparison shows a very good agreement and is better at high latitudes in general. We were able to identify a thermospheric poleward wind reduction possibly linked to a northward turning of the Interplanetary Magnetic Field (IMF) at ~22 UT on Nov 3 and an enhancement of the poleward wind to a southward turning near 10 UT on Nov 4 at high latitudes. An IMF southward turning may have led to an enhancement of equatorward winds at Boulder, Colorado near midnight. Simultaneous occurrence of aurora may be associated with an IMF By turning negative. The MAGE model wind simulations are consistent with observations in these cases. The results show the model can be a very useful tool to further study the magnetosphere and ionosphere coupling on short time scales.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.733-736
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• 2010

Korea Aerospace Research Institute (KARI) performed the preliminary design of liquid rocket engine high-altitude simulation firing test facility for the development and qualification of LRE for the 2nd stage of KSLV-II. The engine high-altitude simulation firing test facility, which are to be constructed at Goheung Space Center, will provide liquid oxygen and kerosene to enable the high-altitude simulation firing test of 2nd stage engine at ground test facility. The high-altitude environment is obtained using a supersonic diffuser operated by the self-ejecting jet from the liquid rocket engine.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.791-797
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• 2018

In this work, the high-altitude environment simulation study was carried out at an altitude of 65 km exceeding Mach number of 6 after the launch of Korean Space Launch Vehicle using a shock tunnel. To minimize the flow disturbance due to the strut support of test model as much as possible, a few different types of strut configurations were considered. Using the configuration with minimum disturbance, the high-altitude environment simulation experiment including a propulsion system with a single-plume, was conducted. From the thruster test through flow visualization, not only a shockwave pattern, but a general flow-field pattern from the mutual interaction between the exhaust plume and the free-stream undisturbed flow, was experimentally observed. The comparison with the computation fluid dynamic(CFD) results, showed a good agreement in the forebody whereas in the afterbody and the nozzle the disagreement was about ${\pm}7%$ due to unwanted shockwave formation emanated from the nozzle-exit.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1148-1152
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• 2017

To simulate a high altitude for rocket at sea level, the test facility should provide a sufficiently low pressure environment. Center Body Diffuser(CBD) is those applied for high altitude simulation test facility. To elucidate the flow characteristics of center body diffuser with various the center body location, numerical analyses using ANSYS FLUENT were performed. The result of this study is deemed to be valuable as a data base for the operation of the Center Body Diffuser.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.647-650
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• 2017

As the necessity of development of supersonic vehicle increases, securing an aerodynamic data from low to high altitude is requested for flying vehicles crusing in various high-tech environment. Therefore our research team built equipment by improving heating device of Model Aerodynamic Facility(MAF) of Konkuk University to simualte a real gas environment. Guided weapon system and temperature and velocity distribution according to the flow that is produced from the pier of supersonic vehicle is planned to be researched by using this equipment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1195-1201
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• 2010

Performance tests of a supersonic exhaust diffuser were conducted by using a liquid rocket engine for simulating high-altitude environment. The experimental setup consisted of a combustion chamber, a vacuum chamber and a diffuser. The combustion tests for simulating high-altitude environment were carried out at three cases by chamber pressure variation(26, 29, 32barg). The test results showed that the diffuser was started at all case and vacuum chamber pressures were approximately 140torr. The starting pressure using combustion gas was similar with that of cold gas, but the vacuum chamber pressure was relatively high because of high temperature in the vacuum chamber. The results of this test can be used as an essential database for the design of real-scale high-altitude simulation test facility in the future.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.115-124
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• 2018

In this study, a cold flow test was carried out on a high-speed vehicle facility with a high-altitude environment simulator. Variable test was carried out according to the blockage ratio, angle, and length of the test model. It is confirmed that the blockage rate can be operated in the range of 40%, and that the model should be selected at an angle of 45 degrees or less. The variables of length are less dominant compared to the variables of blockage rate and angle. Through this, a database is obtained according to the parameters of the conical model of the high-speed vehicle test facility.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.31-34
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• 2007

Performance tests of supersonic exhaust diffuser were conducted by using hot combustion gas for simulating high-altitude environment. The test rig consists of a combustion chamber, a vacuum chamber, water cooling ring and diffuser. Before combustion experiments, the preliminary leak tests were carried out on the liquid rocket engine and diffuser by using high pressure nitrogen(30barg) and a vacuum pump. The leak test results showed that there was no leaks at high pressure and vacuum pressure conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.290-296
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• 2018

In this study, the cold test and the numerical analysis were carried out according to the shape parameters of the test model in order to confirm the operation range of high altitude environment simulation test facility for the supersonic vehicle. The blockage ratio, angle and length ratio were considered as the design parameters. The blockage rate is expected to be limited in the region of more than 40% due to the normal shock and expansion fan. It was confirmed that the angle of model should be selected at the size of 45 degrees or less due to the influence of the strong shock wave. There was no difference in performance between the lengths of 8 times the model diameter. Finally, we obtained the performance database according to the shape parameters of the conical test model and confirmed the operable range of the semi-freejet type high altitude environment simulation test facility.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.248-257
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• 2014

As observed in the recent war, suppression of enemy air defense operation is one of the major tactics, simultaneously conducted with high payoff target. Specifically, our air defense operation should be properly constructed, since the operating environment of our forces mostly consists with mountainous terrain, which makes detections of the enemy difficult. The effective arrangements of low altitude air defense radars can be suggested as a way of improving the detection capability of our forces. In this paper, we consider the location problem of low altitude air defense radar, and formulate it as an Integer Programming. Specifically, we surveyed the previous researches on facility location problems and applied two particularly relevant models(MCLP, MEXCLP) to our problem. The terrain factor was represented as demand points in the models. We verified the optimal radar locations for operational situations through simulation model which depicts simple battle field. In the simulation model, the performance of optimal radar locations are measured by the enemy detection rate. With a series of experiments, we may conclude that when locating low altitude air defense radars, it is important to consider the detection probability of radar. We expect that this finding may be helpful to make a more effective air defense plan.