• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1434-1440
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• 2008

Performance of TCP/IP is studied on the wireless network using flow control and congestion control mechanism based on transmission rate. We discuss the elimination or the reduction of various phenomena of burst by flow controlling on transmission rate and verify that there are TCP ACK compression promblems on the queue by burst reaction while executing transmission rate controlled channels. Analyzing periodic burst reaction on the queue of source IP, the maximum value of queue is expected, which represents the applible expectation of throughput reduce and shows the improvement of performance by the reduce of throughput due to hi-directional traffic.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.8
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• pp.93-98
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• 2009

Cogeneration means the highly energy-efficient generation system that improves energy ratio by generating electricity and heat, and it really affects the improvement of overall efficiency by using industrial process, district heating, and hot-water supply etc. after the energy produced through supplying power to system collects. This thesis indicates the screen of cogeneration flow in LabVIEW and the heat power control system that can be in long-distance control of a district energy system using TCP/IP. We simulated on four computers so that the heat power control system proves long-distance control possible.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.802-808
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• 2014

MEMS based solid propellant thruster researched for the purpose of an academic research will be verified at space environment through CubeSat program. For this, the temperature of the MEMS thruster should be within allowable operating temperature range by proper thermal control to prevent the ignition failure caused by ignition time delay and to guarantee the structural safety of the MEMS thruster in the low temperature. In this study, we proposed an effective thermal control strategy, that is to use micro-igniter as a heater and temperature sensor for active thermal control instead of using additional heater. The effectiveness of the strategy has been verified through on-orbit thermal analysis of CubeSats with MEMS thruster.

• 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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.5
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• pp.466-466
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• 2000

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.20-28
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• 2011

The electro-optical payload of a low-earth orbit satellite is thermally decoupled with the bus, which supports a payload for a mission operation. The payload has a cooling unit of FPA(Focal Plane Assembly) which has a thermal behavior increasing its temperature instantly during an operation in order to dissipate a waste heat into the space. The FPA cooling unit should include a radiator and heatpipes with a sufficient performance in worst hot condition, and a heater design to maintain its temperature above a minimum allowable temperature in the worst cold condition. In this paper, we analyzed the thermal requirements and the heater design constraints from the thermal analysis results for the current thermal design of the FPA cooling unit and the design elements of the better heater design were found.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1994.04a
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• pp.16-22
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• 1994

2.75인치 MK4/40 및 MK66 추진기관용 연소관의 국산화 개발을 목적으로 가공 열처리와 유동성형 공정을 조합한 열가공 유동성형 공정을 적용하여 치수제어시험을 하고 개발품과 수입 연소관을 비교하여 물성 및 구조시험을 실시하여 그 결과를 비교 분석하였다. 개발된 연소관은 수입연소관에 비하여 제작공정이 단축되었고, 열가공 유동성형 공정보다 치수제어에 유리하며, 내경 및 두께 규격을 만족하였다. 또한 물성 및 구조시험 결과 수입 연소관에 비하여 우수한 성질을 나타내었다.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.45-45
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• 2004

현재 개발 중인 저궤도 소형인공위성 발사체, KSLV (Korea Space Launch Vehicle)에 최초로 실리게 되는 ‘발사체 검증위성, KoDSat’ (KSLV Demonstration Satellite)은 발사과정 중에 위성체가 겪게 되는 진동 및 음향레벨 크기를 측정하여 지상국으로 전송하게 된다. 또한 위성체 내부에 설치한 카메라를 이용하여 발사체에서 분리되는 과정을 촬영하여 지상으로 동영상 데이터를 전송하게 된다. 열제어계의 목적은 어떠한 임무기간 동안에도 위성체의 모든 요소들이 각각의 허용 온도범위 내에서 유지되도록 하는데 있다. (중략)

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.28 no.5
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• pp.347-358
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• 1999

암모니아는 독성, 가연성 및 동 재질의 부식성 등의 단점은 있지만 CFC계 냉매가 개발되기 전에는 우수한 열역학 및 열전달 특성 때문에 냉매로서 가장 많이 사용되어져 왔다. 미국에서는 약120년, 일본에서는 약 80년 전부터 암모니아가 냉동 사이클에 사용되었고, 따라서 축적된 관련 기술 수준도 놀고 경험도 많은 편이다. 지금도 미국에서는 상업용 냉동기의 80% 정도가 암모니아를 냉매로 사용하고 있다. 우리나라도 냉동창고 냉동용으로는 암모니아 시스템이 널리 사용되고 있다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.423-429
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• 2014

Passive attitude stabilization methods using the permanent magnet combined with hysteresis damper and the gravity gradient boom have been widely used for the attitude determination and control of cube satellite, due to its advantage of system simplicity. In this paper, on-orbit thermal characteristics of the cube satellite considering the attitude profiles obtained from the above passive attitude stabilization methods have been investigated through on-orbit thermal analysis. In addition, the effectiveness of the various thermal coatings on the panel for the communication antenna installation has been verified.