• Steel and Composite Structures
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• v.35 no.6
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• pp.729-737
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• 2020

The goal of this study is to investigate dynamic responses of laminated composite beams under a moving load with thermal effects. The governing equations of problem are derived by using the Lagrange procedure. The transverse-shear strain and rotary inertia are considered within the Timoshenko beam theory. The material properties of laminas are considered as the temperature dependent physical property. The differential equations of the problem are solved by the Ritz method. The solution step of dynamic problem, the Newmark average acceleration method is used in the time history. A compassion study is performed for accuracy of used formulations and method. In the numerical results, the effects of velocity of moving load, temperature values, the fiber orientation angles and the stacking sequence of laminas on the dynamic responses of the composite laminated beam are investigated.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.681-687
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• 2002

The cumulative, shrinkage plastic strains and their distributions in the weld joint after completion of the welding process determine welding-induced distortion. Although the weldment undergoes many complex physical and metallurgical changes during welding, only the material plastic temperature range and its cooling history below this temperature range influence the [mal state of the cumulative shrinkage plastic strains. In addition, for structural welds, these plastic strains are uniform, except in the arc start and stop regions, along the weld. Therefore, the plastic strain-based "inherent shrinkage model" is effective and accurate to describe welding-induced distortion. This paper presents the theoretical background and numerical verification of this root cause.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.151-156
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• 1997

The setting and hardening of concrete is accompanied by nonlinear temperature distribution caused by developing heat of cement hydration. expecially at early ages, nonlinear temperature distribution has a large influence n the crack evaluation. So the need to predict the exact temperature history in concrete has led to the examination thermal properties. In this study, the convection heat transfer coefficient is experimentally investigated which is one of the thermal properties in concrete. Furthermore, the result of the experiment is compared with those of analysis by the program which is developed in KAIST. As a result of comparison, the analytical results are in good approximation with experimental data.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.430-435
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• 1997

This paper presents the material properties and production of 1400kg/$\textrm{cm}^2$ ultra high-strength concrete in consideration of the history of hydration temperature for the practical utilization. A series of laboratory tests were conducted to optimize the mix proportion and then the full-scall mock up tests were performed to investigate the practicability. The thermal sensors were installed prior to concrete casting into the walls and columns, to measure the hydration temperature during the hardening process, which is inevitable to select the most appropriate curing scheme.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.95-100
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• 2003

The shrinkage of high strength/high performance concrete is very important property for the good working of a structure since it very often generates early age cracking due to thermal and autogenous shrinkage. Autogenous shrinkage occurs as a result of internal moisture depletion due to hydration and temperature-induced effects. The level of autogenous shrinkage occurring due to hydration also depends on temperature history at very early age. It is necessary that effect of temperature on autogenous shrinkage is investigated since the stress generated due to autogenous shrinkage is quantified. In this study, Effect of hydration heat evolution on autogenous shrinkage of high strength concretes with W/C=25-40% was investigated.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.28-32
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• 2003

Thermo-mechanical behavior of a ceramic ball grid array(CBGA) package assembly and wire bond ball grid array(WB-PBGA) package assemblies are characterized by high sensitive moire interferometry. Moire fringe patterns are recorded and analyzed at various temperatures in a temperature cycle. Thermal-history dependent analyses of global and local deformations are presented, and bending deformation(warpage) of the package and shear strain in the rightmost solder ball are discussed. A significant non-linear global behavior is documented due to stress relaxation at high temperature. The locations of the critical solder ball in WB-PBGA package assemblies are documented.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.253-254
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• 2012

In this study, it carried out measurement experiment Ca(OH)₂ and chemically bound water to verify Ca(OH)₂ and chemically bound water prediction model out of hydration model of cement incorporating blast furnace slag. It compared and analyzed prediction results using prediction model with measurement results of Ca(OH)₂ quantity using thermogravimetric differential temperature analysis and chemically bound water quantity using electronic furnace. It agrees well experiments results with prediction results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.974-981
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• 2001

In this study, the minimum heat flux conditions are experimentally investigated for the spray cooling of hot plate. The hot plates are cooled down from the initial temperature of about$ 900^{\circ}C$, and the local heat flux and surface temperatures are calculated from the measured temperature-time history. The results show that the minimum heat flux point temperatures increase linearly resulting from the propagation of wetting front with the increase of the distance from the stagnation point of spray flow. However, in the wall region, the minimum heat flux point temperature becomes independent of the distance. Also, the velocity of wetting front increases with the increase of the droplet flow rate.

• Journal of Welding and Joining
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• v.9 no.2
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• pp.37-43
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• 1991

In order to analyze the mechanical phenomena of three dimensional elato-plastic behavior caused by welding of thick plate, it is necessary to solve exactly the three dimensional unstationary heat conduction problem considering the moving effect of heat source and the temperature-dependence of material properties. In this paper, the three-dimensional unstationary heat conduction problem is formulated by using an isoparametric finite element method. Thereafter, the transient temperature distributions, according to time, of thick plate during welding are defined from the results calculated by the developed computer program.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.160-161
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• 2022

This study is to investigate the temperature history over time of the cement mortar to confirm the bubble sheet insulation effect using the heat generat sheet. As a result of the experiment, it was confirmed that the heating effect was 6℃ higher on average than other types of sheets when the heating sheet is attached on the bottom of the double layered bubble sheet. For future research, it is planned to verify the heating performance by using the heating sheet under the same environmental conditions as the heating performance will be verified.