• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2317-2322
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• 2010

Market for LED lights as a newly-growing industry has been growing, and secureness of high efficiency and long life through optimal thermal design are crucial for further popularization. In this study, considerable improvement in thermal performance for a 10W LED light has been done compared to a previous model. For this, numerical model has been established through experiments and used to optimize design factors in heat release such as fin shape, PCB kind or LED number etc. Furthermore, prototype of a LED light has been made and the improved thermal performance was verified with heat release experiments.

• Journal of Hydrogen and New Energy
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• v.32 no.5
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• pp.347-355
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• 2021

This paper is a study on the thermal design of printed circuit heat exchanger (PCHE) to supply cryogenic high pressure liquid hydrogen stored from hydrogen liquefaction process by using computational fluid dynamics (CFD). This PCHE should be thermally designed to raise the temperature of cryogenic liquid hydrogen to a desired temperature and also to be anti-icing to avoid any local freezing in hot channel. This research presents the effect of inlet velocity and inlet temperature of hydrogen, and the effect of flow configurations of co/counter-flow on thermal design of PCHE heat exchanger based on various CFD simulation analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.306-314
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• 2018

A two-axis gimbal-type X-band antenna for CAS(Compact Advanced Satellite) transmits large amount of image data to ground station regardless of satellite attitude and orbital motion. This antenna mounted on the external surface of the satellite is directly exposed to the extreme space with thermal environment during the orbital operation. Therefore, a proper thermal design is needed to maintain the antenna itself as well as other main components within allowable temperature range. In this study, the thermal design effectiveness of two-axis gimbal X-band antenna was verified through the thermal analysis. In addition, required power and duty cycle of heater were estimated through the thermal analysis under conditions of system level thermal vacuum test and on-orbit thermal environment. The thermal analysis results indicated that all the main components of X-band antenna satisfy the allowable temperature requirement.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.1008-1015
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• 2015

Thermal vacuum test should be performed prior to launch to verify satellites' functionality in extremely cold/hot temperatures and vacuum conditions. A thermal vacuum chamber used to perform the thermal vacuum tests of a satellite system and its components. A cryogenic blower is a core component of the gaseous nitrogen (GN2) closed loop thermal control system for thermal vacuum chambers. A final goal of this research is development of cryogenic blower. Design requirements of a blower are 150 CFM flow rate, 0.5 bara pressure difference, hot and cold temperatures. This paper describes the performance analysis of impeller by 1D, CFD commercial software, the design of the thermal protection interface between the driving part and the fluid part. The performance of the cryogenic blower is confirmed by test at the standard air condition and is verified by on the thermal vacuum chamber at the real operating condition.

• 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 Microelectronics and Packaging Society
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• v.26 no.4
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• pp.23-31
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• 2019

In this study, we conducted numerical analyses using the Taguchi method and finite element method to calculate the thermal deformation of a printed circuit board and the effect of design factors on the thermal deformation. Analysis results showed that the thermal deformation of the panel had the strongest effect on the thermal deformation and shape of the strip and unit. In particular, the deformation in the z direction was larger than that in the xy-plane direction. The effect of design factors and the design conditions for reducing the thermal deformation of the panel and strip changed at the unit level. Therefore, it is recommended that panel-level thermal deformation must be controlled to reduce the final thermal deformation at the unit level because the thermal deformation of the strip strongly affects that of the unit.

• Journal of the Korea Institute of Building Construction
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• v.1 no.2
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• pp.174-178
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• 2001

This study was performed to control the thermal crack of the mat footing slab in the multi-purposed buildings. In this study, we executed the mixing design of concrete to satisfy the workability and the quality according to the site conditions. And, we evaluated quantitatively about the possibility of thermal crack by using hydration heat analysis system. Finally, we proposed the optimal mixing conditions, curing methods and curing period which all factors are considered. As a result, the optimal mixing conditions were : W/B 41%, unit binder 375kgf/$\textrm{m}^3$, FA replacement ratio 20%. Lowest thermal stress was 22.0kgf/$\textrm{cm}^2$ and at that time thermal crack index was over 1.5, when the coefficient of thermal conductivity was lowest among the curing conditions. And, the total curing time was estimated at 6.7 days according to curing steps.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.533-538
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• 2001

This study was peformed to control the thermal crack of the mat footing slab in the multi-purposed buildings. In this study, we executed the mixing design of concrete to satisfy the workability and the quality according to the site conditions. And, we evaluated quantitatively about the possibility of thermal crack by using hydration heat analysis system. Finally, we proposed the optimal mixing conditions, curing methods and curing period which all factors are considered. As a results, the optimal mixing conditions were : W/B 41%, unit binder 375kg/$cm^{2}$, FA replacement ratio 20%. Lowest thermal stress was 22.0kgf/$cm^{2}$ and at that time thermal crack index was over 1.5, when the coefficient of thermal conductivity was lowest among the curing conditions. And, the total curing time was estimated at 6.7 days according to curing steps.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1236-1240
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• 2004

Thermal vacuum test for satellites should be performed before launch to verify the feasibility of satellites' operation in a harsh space environment which is represented as an extremely cold temperature and vacuum condition. A large space simulator(${\Phi}8m{\times}L10m$) has been demanded to accomplish the thermal vacuum test for the huge satellites designed in compliance with the national space program of Korea. In this paper, the design and calculation of thermal shroud which is the core part of large space simulator were discussed. The characteristics of the large space simulator being constructed at Korea Aerospace Research Institute(KARI) were depicted.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.562-566
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• 2004

Thermal shock is a physical phenomenon that occurs in the condition of the exposure of a rapidly large temperature and pressure change of in the quenching condition of material. The rocket nozzle is exposed to high temperature combustion gas, it may have failure and erosion deformation. So, it is important to select a suitable material having excellent thermal shock properties and evaluate these materials in rocket design. In this study, the temperature gradient and crack initiation of rocket nozzle material is investigated using by FEM under thermal shock condition. This is very important information in the design process of thermal structure.