• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.10
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• pp.872-881
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• 2012

The Flight Model (FM) of a high-resolution electro-optical camera (EOS-C Ver.3.0), the mission payload of an Earth observation satellite, was successfully developed by Satrec Initiative. We designed it to give improved thermal representatives compared with the Structural-Thermal Model (STM) by optimizing the thermal characteristics based on the STM thermal vacuum test results. We developed the FM and verified the workmanship by performing the acceptance level thermal vacuum test. We also conducted the verification of its Thermal Mathematical Model (TMM) by the thermal balance test. As the result, it was confirmed that TMM faithfully represents the thermal characteristics of the EOS-C Ver.3.0 FM.

• Journal of Astronomy and Space Sciences
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• v.26 no.3
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• pp.403-416
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• 2009

COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and developed by KARl for communication, ocean and meteorological observations. It will be tested under vacuum and very low temperature conditions in order to verify thermal design of COMS. The test will be performed by using KARI large thermal vacuum chamber, which was developed by KARI, and the COMS will be the first flight satellite tested in this chamber. The purposes of thermal balance test are to correlate analytical model used for design evaluation and predicting temperatures, and to verify and adjust thermal control concept. KARI has plan to use heating plates to simulate space hot condition especially for radiator panels of satellite such as north and south panels. They will be controlled from 90 K to 273 K by circulating GN2 and LN2 alternatively according to the test phases, while the main shroud of the vacuum chamber will be under constant temperature, 90 K, during all thermal balance test. This paper presents thermal modelling including test chamber, heating plates and the satellite without solar array wing and Ka-band reflectors and discusses temperature prediction during thermal balance test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.10
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• pp.729-737
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• 2022

Melting and icing process of the PCMTCU(Phase Change Material Thermal Control Unit) installed on the NEXTSat-2, which is scheduled to be launched in the second half, was investigated through the results of satellite-level TVT(Thermal Vacuum Test). As a result of the test, it was confirmed that the latent heat of PCM contributes to the temperature stabilization of the heating components. The thermal model for numerical analysis of the PCMTCU was correlated to acquire a reasonable degree of accuracy using the collected temperature measurements during TVT. The periodic temperature variation of the PCMTCU in normal on-orbit operation was predicted with the correlated thermal model, and the quantitative contribution of the PCM on the thermal energy management was evaluated with the liquid fraction. It will receive flight telemetry from the NEXTSat-2 after the launch, and complete the space verification of the PCMTCU.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.814-821
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• 2015

The STEP Cube Lab. classified as a pico-class satellite has been successfully developed as a flight model(FM) to be launched in 2015. Its mission objective is to perform the on-orbit verification of fundamental space core-technologies. In this study, a thermal design concept based on the passive method to achieve the mission objective is introduced. The effectiveness of the thermal design and performance of the satellite has been verified through the acceptance level thermal vacuum test. In addition, to improve the reliability of thermal mathematical model, correlation was performed using the results of thermal balance test. This paper describes a series of process for the thermal vacuum test on the STEP Cube Lab. FM.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.106-114
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• 2005

This study addresses space simulation test results and thermal modelling verification of HAUSAT-2 nanosatellite STM (Structural-Thermal Model). The thermal modelling of the HAUSAT-2 has been modified in accordance with test results. Thermal analysis results were repeatedly compared with test results for modified thermal modelling. It is verified that the analysis results for modified thermal modelling agree well with test results. Some surface heaters were implemented to simulate solar illumination for HAUSAT-2 Thermal Vacuum/Balance Test. A low-cost and effective thermal test methodology, which is applicable to ultra-small satellite system, was proposed and verified by test results in this study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.156-164
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• 2016

Qualification model(QM) of main payloads including concentrating photovoltaic system using fresnel lens, heating wire cutting type shockless holding and release mechanism, and MEMS-based solid propellant thruster have been developed for the STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project), which is a pico-class satellite for verification of core space technologies. In this study, we have verified structural safety and functionality of the developed payloads under a qualification temperature range through the QM thermal vacuum test. Additionally, a reliability of thermal model of the payloads has been confirmed by performing a thermal correlation based on the thermal balance test results.

• Current Industrial and Technological Trends in Aerospace
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• v.8 no.1
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• pp.55-61
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• 2010

Thermal vacuum test should be carried out to verify the performance of the S/C on the ground under the simulated space environment. KARI already completed the construction of a Large Thermal Vacuum Chamber(LTVC) with 8 m of diameter and 10 m of length dimension. LTVC is for the purpose of performing the orbital environment test for large Space Craft(S/C). Inside LTVC, S/C is much smaller than LTVC. For the function test of S/C during the thermal vacuum test, the S/C has to be connected to Electrical Ground Support Equipment(EGSE) which includes several cable and RF wave guide inside LTVC. Also, MLI should be installed on S/C before the test. But it is very difficult to access the S/C inside big LTVC. To solve the accessibility to the S/C inside LTVC, KARI designed an access fixture. This fixture provides easy access to the any S/C thus can help safe installation and saving time for the related work inside LTVC. This paper describes whole process for the design of the access fixture.

• Progress in Superconductivity and Cryogenics
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• v.15 no.4
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• pp.53-58
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• 2013

KSTAR in-vessel cryo-pump has been installed in the vacuum vessel top and bottom side with up-down symmetry for the better plasma density control in the D-shape H-mode. The cryogenic helium lines of the in-vessel cryo-pump are located at the vertical positions from the vacuum vessel torus center 2,000 mm. The inductive electrical potential has been optimized to reduce risk of electrical breakdown during plasma disruption. In-vessel cryo-pump consists of three parts of coaxial circular shape components; cryo-panel, thermal shield and particle shield. The cryo-panel is cooled down to below 4.5 K. The cryo-panel and thermal shields were made by Inconel 625 tube for higher mechanical strength. The thermal shields and their cooling tubes were annealed in air environment to improve the thermal radiation emissivity on the surface. Surface of cryo-panel was electro-polished to minimize the thermal radiation heat load. The in-vessel cryo-pump was pre-assembled on a test bed in 180 degree segment base. The leak test was carried out after the thermal shock between room temperature to $LN_2$ one before installing them into vacuum vessel. Two segments were welded together in the vacuum vessel and final leak test was performed after the thermal shock. Commissioning of the in-vessel cryo-pump was carried out using a temporary liquid helium supply system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.2
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• pp.178-183
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• 2012

To simulate space thermal environment in thermal vacuum test, direct or in-direct heater has been applied on the radiator. Both of them, direct heater attached on the radiator and indirect heater with a distance from the radiator, simulate the heat fluxes from the Sun radiation, the Earth IR and Albedo. They also supply the heat fluxes to the radiator of spacecraft to achieve the target temperature according to thermal test conditions. In general, indirect heater is used when the heater is not allowed to attach on the radiator directly due to constraints of coating property or contamination. For in-direct heater design, it is needed to estimate the heat power to make the extreme test conditions and minimize the interference with heat exchange of radiator and shroud. In this study, optimized thermal design of in-direct heater is proposed and investigated by commercial S/W SINDA. The effective values of design factors are also derived.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.361-364
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• 2009

Vacuum facility is required for high altitude space environment test to develop small thruster to be applied for micro-satellite. After selecting vacuum equipment and integrating the chamber to simulate 100-120km attitude with max, $10^{-5}\;torr$. We tested the performance of high vacuum chamber. We designed, fabricated the knudsen pump and analyzed pressure gradient efficiency of membrane according to Knudsen number under vacuum conditions. We described the upgrade plan to a thermal vacuum chamber.