• Computational Structural Engineering
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• v.7 no.3
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• pp.123-131
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• 1994

This paper is concerned with a new concept of vibration control in which thermal stresses are utilized. Thermal actuators are used to generate thermal stresses in a vibrating beam. The thermal actuators are found to work successfully as the control means. Especially the proposed control method in this paper can be effectively applied to the large space structures with low natural frequencies rather than to the structures with high natural frequencies. In the process of control design, various control methods including optimal-robust control method are investigated. Through numerical simulations, it is found that the robust-optimal control method can be efficiently with the vibration control of a cantilever beam using thermal stresses.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.107-116
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• 2005

As a unique payload of Komsat-2, MSC, comprising EOS(Electro-Optical Sub-system), PMU(Payload Management Unit) and PDTS(Payload Data Transmission Sub-system), is supposed to take pictures of one panchromatic and 4 multi-spectral image between wavelength 450mm~900mm, and is being under final Satellite I&T. It will perform the earth remote sensing with applications such as acquisition of high resolution images, surveillance of large scale disasters and its countermeasure, survey of natural resources, etc.. Under the hostile influence of the extreme space environmental conditions due to deep space and direct solar flux, the thermal design is especially of major importance in designing a payload. There are tight temperature range restrictions for electro-optical elements while on the other hand there are low power consumption requirements due to the limited energy source on the spacecraft. This paper describes details of thermal control system for MSC.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1222-1228
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• 2008

A small satellite, DubaiSat-1 FM(Flight Model), which is based on SI-200 standard bus platform and scheduled to be launched in 2008, is being developed by Satrec Initiative and EIAST(Emirates Institution for Advanced Science and Technology). The TCS(Thermal Control Subsystem) of DubaiSat-1 FM has been designed to mainly utilize passive thermal control in order to minimize power consumption, but the active control method using heaters has been applied to some critical parts. Also, thermal analysis has been performed for DubaiSat-1's mission orbit using a thermal analysis model. The thermal design is modified and optimized to satisfy the design temperature requirements for all parts according to the analysis result. The thermal control performance of DubaiSat-1 FM is verified by thermal vacuum space simulation, consisting of thermal cycling and thermal balance test. Also, to validate the thermal modeling of DubaiSat-1 FM, comparison of test results with analysis has been performed and model calibration has been completed.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.04a
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• pp.275-280
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• 1998

인간의 감성에 영향을 미치는 요인은 다양하나 이 중에서도 열환경은 인간에게 미치는 정도가 어떠한 요인보다도 큰 것으로 알려져 있다. 열환경이라 함은 온도, 습도, 기류, 복사열을 말하며 이 요소들과 인간의 감성과는 밀접한 관련을 지닌다. 열환경과 관련된 인간의 감성을 측정, 평가하기 위해서는 주위의 열환경이 정밀하게 제어되는 공간에서 작업이 이루어져야 한다. 실내 공간의 열환경을 임의로 제어하기 위해서는 급기되는 공기의 조건과 벽체의 온도가 정밀하게 제어되어야 한다. 공기와 벽체 조건은 가열, 냉각, 가습 또는 제습에 의하여 정밀하게 제어되며 이를 실현하기 위하여 공조 시스템은 일반적인 시스템과는 달리 특수한 조건이 요구된다. 공조 시스템의 각 구성요소가 컴퓨터에 의해 개별적으로 제어될 수 있어야 하며 특수 조건에 따른 유연성이 뛰어나야 한다. 본 연구에서는 열환결 제시에 적합한 공조 시스템을 개발한다.

• 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 Astronomy and Space Sciences
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• v.13 no.2
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• pp.105-116
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• 1996

This study is based upon the thermal modeling, analysis and operational results of KITSAT-1 and KITSAT-2 microsatellites launched on August 11, 1992 and Septermber 26, 1993, respectively. As KITSAT-1/2 was designed to be launched as an auxiliary payload of ARIANE launcher, the constraints on volume, power consumption, and mass were required to adopt passive thermal control method controlling absorptivity, emissivity, and conductivities among adjacent modules. The main of KITSAT was to take Earth images using CCD cameras positioned at the bottom of spacecraft, in which the cameras were always pointing to the center of Earth. This study is concerned with orbital analysis, thermal modeling, simulation results, and its verification by utilizing in-orbit telemetry data of KITSAT-2. The results of telemetry analysis show that the thermal modeling is matched to actual temperature data within 10 degrees of error range in average.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.857-862
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• 2014

The research on a thermal stress control layer (TSCL) begins to undertake to reduce residual stress and strain in the vicinity of the joined region between the hardfacing layer and the base part. The goal of this paper is to estimate the material combination and the thickness of TSCL for the Stellite21 hardfaced STD61 hot working tool steel via three-dimensional finite element analysis (FEA). TSCL is created by the combination of Stellite21 and STD61. The thickness of TSCL ranges from 0.5 mm to 1.5 mm. The influence of the material combination and the thickness of TSCL on temperature, thermal stress and thermal strain distributions of the hardfaced part have been investigated. The results of the investigation have been revealed that a proper material combination of TSCL is Stellite21 of 50 % and STD61 of 50 %, and its appropriate thickness is 1.0 mm.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.173-175
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• 2012

데이터 센터와 같은 대량의 서버를 사용하는 시설이 늘어남에 따라 전력 소모 관리와 열 발생 관리는 매우 중요한 문제가 되었다. 열 관리 연구들의 경우 대부분 열관리의 목적이 시스템의 오류를 방지하는 것이다. 하지만 열 관리에는 많은 전력 소모량이 사용된다. 따라서 열관리를 잘 해주는 것은 전력 관리를 효율적으로 해주는 것이라고 할 수도 있다. 본 논문은 열 관리를 전력 관리라는 측면에서 접근했다. 즉 열 관리에 사용되는 전력과 열로 인해 발생하는 전력을 고려해서 이를 최소화하는 냉각 제어 기법을 구현하였다. 우리가 개발한 냉각 제어 기법을 실제로 실험해서 기존의 냉각 기법과 비교해본 결과 전력 소모량을 17% 감소시키는 것을 확인 할 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.3
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• pp.237-242
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• 2012

Spaceborne pulse tube-type cryogenic compressors are widely used for space applications. To guarantee cooling performance of the compressor, mission life time and micor-vibration stability, suitable thermal control of compressor is required. Micro-vibration of the compressor is the one of the sources to degrade the pointing performance of observation satellite. In the present work, on-orbit thermal design of compressor in order not to degrade the performance of micro-vibration isolation system keeping the thermal control performance has been proposed and investigated through thermo-mechanical analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.921-930
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• 2013

Satrec Initiative successfully developed and verified a high-resolution electro-optical camera system, EOS-D Ver.1.0. We designed this system to give improved spatial and radiometric resolution compared with EOS-C series systems. The thermal control subsystem (TCS) of the EOS-D Ver.1.0 uses heaters to meet the opto-mechanical requirements during in-orbit operation and uses different thermal coatings and multi-layer insulation (MLI) blankets to minimize the heater power consumption. Also, we designed and verified a refocusing mechanism to compensate the misalignment caused by moisture desorption from the metering structure. We verified the design margin and workmanship by conducting the qualification level thermal vacuum test. We also performed the verification of thermal math model (TMM) by comparing with thermal balance test results. As a result, we concluded that it faithfully represents the thermal characteristics of the EOS-D Ver.1.0.