• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.116-116
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• 2012

위성의 발사, 천이궤도, 운영궤도 등에서 위성체에 주어지는 극한 온도와 진공상태에서 위성체와 열제어시스템이 요구 조건을 만족시키는가를 확인하기 위하여 열진공시험을 수행한다. 우주에서 일어나는 환경변화는 극도로 심해서 지상에서 이와 유사한 열적 환경을 모사하는 방법은 쉽지가 않고, 일반적으로 위성체에 대한 열진공/평형 시험을 위해서는 열유속 흡수법과 열유속 투사법의 두 가지 방법을 사용한다. 한국항공우주연구원에서는 종래 접촉식 히터를 위성체에 직접 부착하는 방법에서 탈피하여 새로이 IR Lamp를 이용한 열유속 흡수법을 이용하여 위성체에 계산된 열유속을 인가하는 방법으로 위성체 열진공/평형시험을 수행하였으며, IR Lamp는 요구되는 100W~400W 사이의 열량을 오차 범위 5% 이내로 인가하여 균일한 온도 분포를 유지하고 성공적인 시험을 수행하였다.

• 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.

• 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.34 no.12
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• pp.90-95
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• 2006

The wall of thermal vacuum chamber which is used for the satellite thermal balance test doesn't absorb satellite's IR emission perfectly and reflects some part of that. It is estimated that small thermal vacuum chamber has relatively larger wall effect than the big one. The small thermal vacuum chamber is required for the small satellite test to reduce the test cost. A quantitative analysis was carried out to investigate the chamber wall effect. As a result, temperature errors caused by chamber wall effect was calculated, and the temperature data acquired in the thermal balance test have been compensated. By defining the optimized area ratio between chamber surface and satellite surface area, the baseline to be able to determine the minimum size of thermal vacuum chamber was established to minimize the wall effect. Also, theoretical analysis about transparent material coating which can reduce the chamber wall effect is conducted.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.71-77
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• 2017

In the event of loss of coolant accident (LOCA) and station black out (SBO) in the primary system of a nuclear reactor, the coolant water should be injected to reactor coolant system (RCS) without any intervention of operators or active components. To satisfy the requirements, hybrid safety injection tank (Hybrid SIT) was suggested by Korea Atomic Energy Research Institute (KAERI). The pressure equalizing time of Hybrid SIT is an important parameter to determine the timing of coolant injection. To predict the pressure equalizing time of the Hybrid SIT, a separate effect test facility was constructed and sensitivity tests were conducted in various conditions. The main parameter determining the pressure equalizing time was obtained from separate effect test (SET) results. The wall of condensation on the inner wall of SIT and direct contact condensation on the water surface affected to the pressure equalizing time very much. In this study, the effect of each condensation phenomena on pressure equalizing time was quantitatively analyzed from results of SET and a prediction method of pressure equalizing time was proposed.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.103.2-103.2
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• 2015

10-3 Pa 이하의 고진공 환경과 $180^{\circ}C$ 이하의 극저온 환경에서 대형정지궤도위성의 고온 열평형 환경구현을 위한 열제어패널이 설계되었다. 열제어패널은 가로 2.2 m, 세로 2.6 m, 두께 2 mm의 구리판에 구리 튜브가 브레이징되어 있는 형태로 설계되었으며, 지상에서 6 m 이상의 높이에 설치되고 위성의 위치에 따라 이동이 가능해야 하기 때문에, 별도의 지지 구조물이 함께 설계되었다. 따라서, 열제어패널 설치 및 고정을 위한 지지구조물의 경우 160 kg의 무게를 견뎌내야 하며 이동 및 설치에 있어 구조적인 안전성이 확보 되어야 한다. 이에 본 연구에서는 상용유한요소해석 프로그램을 사용하여 열평형시험 시 위성체 상단부의 고온 환경모사를 위한 열제어패널 지지구조물에 대한 구조 안전성을 확인 하였다.

• Journal of the Korean institute of surface engineering
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• v.29 no.3
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• pp.176-185
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• 1996

플라즈마 용사된 열벽코팅의 수명을 평가하기 위하여 여러가지 양의 CeO$_2$(16,18,20,22,24 그리고 26 wt.% CeO$_2$)를 포함하는 지르코니아 코팅에 대한 상분석이 행하여 졌다. 플라즈마 용사된 후 16 및 18 wt.% CeO$_2$를 포함하는 지르코니아 코팅에서는 비평형 tetragonal 상 만이 생성되었으나 20-26 wt.% CeO$_2$를 포함하는 지르코니아 코팅에서는 비평형 tetragonal 및 cubic 상의 혼합상이 관찰되었다. 열순환 산화시험 동안에는 비평형 tetragonal 및 cubic 상은 평형 tetragonal 및 cubic 상으로 변태하였다. 평형 tetragonal 상의 일부는 열순환 산화시험의 냉각과정 중에 monoclinic 상으로 변태하였다. 그리고 16 wt.% CeO$_2$를 포함하는 지르코니아 코팅은 다른 조성의 지르코니아 코팅보다 열순환 산화시험 동안 더 많은 monoclinic 상이 생성되었으며 세라믹 코팅 수명이 짧았다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.7-10
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• 2006

A quasi-equilibrium model is used in order to aid movement and ballistic analysis for a propellant actuated device(PAD) system. The validity of the model is examined by experiments of a PAD system. The appropriateness of its usage for application was explored by comparing the tendency of experiments and analysis results, and the coefficients of friction and heat loss were obtained. The design method developed will be applied to the design of PAD systems.

• 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.