• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.847-856
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• 2004

Heaters for the spacecraft propulsion system are sized to prevent propellant from catastrophic freezing. For this purpose, thermal mathematical model (TMM) of the propulsion system is developed. Calculation output is compared with the results obtained from thermal vacuum test in order to check the validity of TMM. Despite a little discrepancy between the two types of results, both of them are qualitatively compatible. It is concluded that the propulsion system heaters are correctly sized and TMM can be used as a thermal design tool for the spacecraft propulsion system.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.103-108
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• 2004

The space environment is characterized such a severe condition as high vacuum and very low temperature. Since a satellite will be exposed such a space environment as soon as it goes into the its orbit, thermal vacuum test should be carried out to verify the performance of the satellite on the ground under the space environmental conditions. KARI has a thermal vacuum chamber with useful dimensions of ∮3.6m×L3m, in which KOMPSAT-1 and KOMPSAT-2 satellites were tested. But very large thermal vacuum chamber with useful dimensions of ∮8m×L10m has been needed to meet the future demand of large satellites. Generally, the thermal vacuum chamber can be divided into a vacuum system and a thermal system. Especially, a cryogenic system in the thermal system simulates very low temperature of -196℃ under the high vacuum condition. In this paper, we propose the new cryogenic system can be applied to the future large thermal vacuum chamber.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.64-73
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• 2007

A Large thermal vacuum chamber (LTVC) for space environment simulation on large satellites was successfully developed and constructed by KARI (Korea Aerospace Research Institute) in Korea with a local company. This chamber has an effective diameter of 8 meters and depth of 10 meters, and is composed of vacuum system, thermal control system, and anti-vibration system. Temperature below $-190^{\circ}C$ is maintained over the thermal shroud wrapping a satellite under $3.7{\times}10^{-5}Pa$ ($5{\times}10^{-7}torr$) vacuum level, and optical test can be done in this chamber by seismic mass with $10^{-5}g_{rms}$ or lower vibration level. In addition, the shroud temperature can be increased up to $123^{\circ}C$ using halogen lamps. Chamber control program based on PLC (Programmable Logic Controller) could control this large thermal vacuum chamber automatically.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.270-277
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• 2008

Vacuum is any air or gas pressure less than a prevailing pressure in an environmental or, specifically, any pressure lower than the atmospheric pressure and is used by a wide variety of scientists and engineering - including clean environment, thermal insulation, very long mean free path, plasma, space simulation[1]. The space environment is characterized by such a severe condition as high vacuum, and very low and high temperature. Since a satellite will be exposed to such a space environment as soon as it goes into its orbit, space environmental test should be carried out to verify the performance of the satellite on the ground under the space environmental conditions. A general and widely used method to simulate the space environment is using a thermal vacuum chamber which consists of vacuum vessel and thermally controlled shroud. As indicated by name of vacuum chamber, the vacuum technology is applied to design and manufacture of the thermal vacuum chamber. This paper describe the vacuum technology which is applied to space business.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.949-952
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• 2005

According to the national space program in Korea, is satellites will be launch into space up to 2015. Especially, KARI is going to develope of its own a high resolution camera of less than 1m to be mounted on next Multipurpose Satellite. When performing testing of large spacecraft or hardware that will be launched into orbit, it is necessary to conduct a testing with space-simulated environment. To achieve this requirement, thermal vacuum chamber is generally used. KARI has been developed a very Large Thermal Vacuum Chamber(LTVC) from 2003 to accomodate future space program, such as KOMPSAT, COMS, and Launch vehicles. This new facility will be used to qualify the first self developed High Resolution Camera, which will be loaded on KOMPSAT-3. To perform an optical test for space camera, it is necessary to provide vibration free environment. Thus the vibration responses on the optical table due to external vibration should be minimized by using a special isolation system. In this paper, we propose the concept design of vibration isolation system for the development of the high resolution camera.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.4 s.235
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• pp.526-536
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• 2005

A heat dissipation modeling method of EEE parts, or semi-empirical heat dissipation method, is developed for thermal design and analysis an electronic equipment of geostationary satellite. The power consumption measurement value of each functional breadboard is used for the heat dissipation modeling method. For the purpose of conduction heat transfer modeling of EEE parts, surface heat model using very thin ignorable thermal plates is developed instead of conventional lumped capacity nodes. The thermal plates are projected to the printed circuit board and can be modeled and modified easily by numerically preprocessing programs according to design changes. These modeling methods are applied to the thermal design and analysis of CTU (Command and Telemetry Unit) and verified by thermal cycling and vacuum tests.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.91-95
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• 2005

A heat dissipation modeling method of EEE parts is developed for thermal design and analysis of an satellite electronic equipment. The power consumption measurement value of each functional breadboard is used for the heat dissipation modeling method. For the purpose of conduction heat transfer modeling of EEE parts, surface heat model using very thin ignorable thermal plates is developed instead of conventional lumped capacity nodes. The thermal plates are projected to the printed circuit board and can be modeled and modified easily by numerically preprocessing programs according to design changes. These modeling methods are applied to the thermal design and analysis of CTU and verified by thermal cycling and vacuum tests.

• Journal of Aerospace System Engineering
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• v.2 no.4
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• pp.25-30
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• 2008

In general, we utilize momentum wheel to control spacecraft. It needs vacuum test to analyze the effect of space environments. The conventional vacuum connector which is composed of steel has problems for test with built in momentum wheel because of weight, thermal expansion, etc. We suggest possibility to manufacture the vacuum connector using aluminum mount, epoxy and industrial D-Sub considering cost, weight. We verify the performance through vacuum test.

• Journal of computational fluids engineering
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• v.11 no.2 s.33
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• pp.32-39
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• 2006

A heat dissipation modeling method of EEE parts is developed for thermal design and analysis of an satellite electronic equipment. The power consumption measurement value of each functional breadboard is used for the heat dissipation modeling method. For the purpose of conduction heat transfer modeling of EEE parts, surface heat model using very thin ignorable thermal plates is considered instead of conventional lumped capacity nodes. These modeling methods are applied to the thermal design and analysis of CTU EM and EQM and verified by thermal cycling and vacuum tests.

• Journal of Korean Vacuum Science & Technology
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• v.7 no.2
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• pp.27-32
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• 2003

A large cryo-pumping system composed of 4 cryosorption pumps was designed and manufactured to satisfy the pressure requirements of the NBI test stand. The cryosorption pump consists of a thermal shield/baffle assembly and a cryopanel coated with activated carbon granules. The thermal shield is cooled by liquid nitrogen, and the cryopanel by a commercial helium refrigerator. The operation characteristics and vacuum performance of the cryosorption pump were investigated. The cooling down time of the cryopanel to 20 K was about 6 hours with a liquid nitrogen consumption rate of about 35 L/hr. The maximum pumping speed of the cryosorption pump for the hydrogen gas measured by the steady pressure method was about 90,000 L/s.