• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3035-3043
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• 2015

This study evaluates the thermal structural safety of the three-way catalyst(TWC) substrate for domestic passenger cars. Thermal-fluid boundary conditions on the TWC substrate were determined by D-optimal DOE. The thermal stresses on the TWC substrate were calculated by the temperature distribution obtained from the CFD results. The safety factors of the TWC substrate were determined by statistical strength and stress distributions and estimated to be 0.275. The thermal stresses for TWC substrate exceeded the strength of the material. Therefore, it is necessary to redesign the TWC substrate because it has much shorter service life than design life.

• Journal of Satellite, Information and Communications
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• v.2 no.1
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• pp.21-26
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• 2007

LEO Satellite that observes earth with optical camera or synthetic aperture radar is placed at hundreds of kilometers altitude and undergoes severe thermal load. The thermal deformation of structure by the thermal load makes payload not to point toward wanted ground position. The payload pointing direction change by thermal distortion is called thermal pointing error. This is carried out by 3 steps that are thermal analysis, temperature conversion and structural analysis. In this paper, the possibility of successful mission through thermal pointing error analysis is described.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.249-252
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• 2008

In recent large-scale structures, as mass concrete type structure is frequently applied to the building, temperature crack due to hydration heat needs to be considered. Since a volume change is internally or externally restricted in a mold after placing concrete, temperature crack of mass concrete takes place. By this reason, the reduction method to control this crack is required. In this study, low heat mixture and hydration heat difference is used to execute the analysis of hydration heat, considering the changes of heat transfer coefficient according to curing conditions and block placement of mass concrete. For the analytical modelling, original portland cement and concrete of low heat mixture are placed in the upper and lower payer, respectively. A convection boundary condition is fixed because mass concrete of block placement is characterized by the difference of mold form and curing condition. Through the analysis results considering the changes of low heat mixture, block placement, and heat transfer coefficient, we check out the temperature and stress distribution and analyze the temperature crack reduction effect.

• 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.

• Journal of Korean Society of Steel Construction
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• v.27 no.4
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• pp.387-397
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• 2015

The domestic fire resistance performance test is conducted as a prescriptive design method such as quality test. In quality test there are 2 methods, unloaded fire resistance test and fire resistance test under load. In realistic, these tests, however, have problems with expense, time and diversity of structure. This study reviewed fire resistance performance of H-beam flexural member by thermal stress analysis using finite element ABAQUS program. This research is for the performance-based design reviewing applicability of domestic standard. As a result of this study, limit temperatures per each load ratio provied for proper performance of fire resistancy.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.119-122
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• 2011

분자동역학 전산모사를 통하여 에폭시에 다양한 반경의 구형 실리콘 카바이드를 삽입한 나노복합재를 모델링하고, 이들의 기계적 물성과 열적 물성 해석을 다양한 온도조건 하에서 수행하였다. 전산모사 결과 동일한 체적분율 하에서 나노복합재는 입자의 크기가 작아질수록 탄성계수와 전단계수가 상승하는 동시에 선팽창계수는 감소하는 입자의 크기효과를 보였다. 또한 온도 상승에 따른 기계적 물성의 하락이 잘 관찰되었다. 본 연구에서는 이러한 분자동역학 해석 결과를 바탕으로 다양한 온도조건 하에서의 입자의 크기효과를 고려한 멀티스케일 3상 모델을 제시하였다. 유리상 조건 범위에서 온도 변화에 따른 나노복합재 계면의 열응력텐서와 열변형률텐서의 정보를 통해 복합재 내에서 계면이 차지하는 부피비를 온도에 대한 함수로 고려하고, 이를 멀티스케일 모델에 반영함으로써 다양한 온도조건에 대한 나노복합재 열탄성 물성의 예측해를 제시하였다. 본 연구에서 제시한 모델에서 계산된 3상 복합재의 물성은 분자동역학 전산모사의 결과에서 나타나는 나노입자의 크기효과를 잘 반영하였다.

• 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 Geotechnical Society
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• v.37 no.10
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• pp.27-40
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• 2021

The construction method to prevent the frost heave or thaw settlement is called the ground stabilization method, and the thermo-syphon is one of the typical ground stabilization methods. The thermo-syphon has recently been developed with a simple analysis model and thermal analysis has been carried out, but the frost heave of frost susceptible soil was not considered. This study was conducted using ABAQUS internal user subroutine to develop the numerical analysis model (Coupled thermo-mechanical) that can simultaneously perform thermal analysis for the temperature change of the soil according to the thermo-syphon and structural analysis to predict the frost heave of the soil accordingly. As a result of the numerical analysis, the frost heave of the soil decreased as the performance of the thermo-syphon increased. As for the main results, when the thermo-syphon which has contain 25%, 50%, and 100% of refrigerant filling ratio was applied, the reduction ratio of the frost heave was 5.5%, 14.4%, and 21% respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.6
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• pp.17-23
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• 2009

The survivability of the temporary nozzle extension for an accurate thrust measurement in a full-scaled combustor has been investigated through thermal analyses. The effects of nozzle extension materials and the thickness of thermal barrier coating (TBC) have been elucidated. It has been found that thermal survivability cannot be guaranteed without TBC. The maximum temperature of the nozzle extension decreased with increasing TBC thickness. For hot firing tests, the TBC is thought to be indispensable to the thermo-structural survivability of the nozzle extension made of steel.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.113-122
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• 2010

A two-dimensional thermal response and ablation analysis code for predicting charring material ablation and shape change on solid rocket nozzle is presented. For closing the problem of thermal analysis, Arrhenius' equation and Zvyagin's ablation model are used. The moving boundary problem are solved by remeshing-rezoning method. For simulation of complicated thermal protection systems, this method is integrated with a three-dimensional finite-element thermal and structure analysis code through continuity of temperature and heat flux.