• Steel and Composite Structures
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• v.15 no.1
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• pp.57-79
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• 2013

This paper studies the dynamic instability of laminated composite plates under thermal and arbitrary in-plane periodic loads using first-order shear deformation plate theory. The governing partial differential equations of motion are established by a perturbation technique. Then, the Galerkin method is applied to reduce the partial differential equations to ordinary differential equations. Based on Bolotin's method, the system equations of Mathieu-type are formulated and used to determine dynamic instability regions of laminated plates in the thermal environment. The effects of temperature, layer number, modulus ratio and load parameters on the dynamic instability of laminated plates are investigated. The results reveal that static and dynamic load, layer number, modulus ratio and uniform temperature rise have a significant influence on the thermal dynamic behavior of laminated plates.

• Journal of Energy Engineering
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• v.26 no.1
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• pp.9-22
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• 2017

A combined thermal and flow analysis was carried out to study the behavior and performance of a small, commercial LTD (Low-Temperature-Differential) heat engine. Laminar-flow solutions for annulus and channel flows were employed to estimate the viscous drags on the piston and the displacer and the pressure difference across the displacer. Temperature correction factors were introduced to account for the departure from the ideal heat transfer processes. The analysis results indicate that the work required to overcome the viscous drags on engine moving parts and to move the displacer is much smaller than the moving-boundary work produced by the power piston for temperature differentials in the neighborhood of $20^{\circ}C$ and engine speeds below 10 RPS. A comparison with experimental data reveals large degradations from the ideal heat transfer processes. Thus, heat-transfer devices inside the displacer cylinder are recommended.

• Fire Science and Engineering
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• v.15 no.1
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• pp.108-115
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• 2001

In this paper, we analyzed the properties change of electric wire when the thermal stress was applied to 600V grade polyvinyl chloride insulated wire (IV). In the structure analysis, normal wire has the properties of direction on the surface, but in case of deteriorated wire at above $400^{\circ}c$, it formed the carbide, the crack and the crystal. The surface composition rate of normal wire was Cu : 100%, but the section composition of the deteriorated wire at $800^{\circ}c$ showed Cu : 78.89%, O : 21.11%. In result of analyzing the differential scanning calory of copper wire, the new reaction peak was observed on the deteriorated wire at above $700^{\circ}c$. In case of the deteriorated wire as $150^{\circ}c$ at the differential thermal analysis, an endothermic reaction appeared at $264^{\circ}c$ lower than the reactive point of normal wire. The occupation rate of oxygen according to the deterioration of copper wire is about 20% at $500^{\circ}c$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.37-38
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• 2017

In Infrared rays, which are 50% of sunlight, act as heat rays to heat buildings. Solar heat paint is widely used to protect buildings from sunlight. Solar heat coatings are used to block buildings form sunlight. Solar heat paints are classified as heat-reflective paints and heat-insulating paints according to the differential thermal mechanism. In this study, we study the thermal differential mechanism by analyzing the temperature change of the coated steel plate and the solar reflection spectrum on the surface. In this experiment, exposed steel plate, heat-reflective coated steel plate, heat-insulating coated steel plate, and general paint coated steel plate were used. As a result, when the infrared rays of 780nm ~ 1400nm were irradiated, the heat reflective paint had a temperature lower by 10 degrees than other paints. Analysis of the reflection spectrum of the paint shows that the heat paint is lower in heat than other paints because it has higher reflectance of light and absorbs much of the infrared rays.

• Journal of the Korean Society of Tobacco Science
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• v.3 no.2
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• pp.89-93
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• 1981

Some or the parameters affecting the thermal analysis of different types of ground tobacco have been discussed. The sample, Korean flue- cured and burley and Greek orient tobacco leaves were run in air at heating rate of $10^{\circ}$ and 20^{\circ}C$ per minute. The thermograms obtained were divided into four temperature zones. The effect of different heating rates on thermal degradation has been discussed At the lower heating rate the maxima of DTA curves in zone 3 and 4 were 25-$40^{\circ}C$ lower than that of the higher heating rate.

• Steel and Composite Structures
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• v.50 no.4
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• pp.459-474
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• 2024

Classical and first-order nonlocal beam theory are employed in this study to assess the thermal buckling performance of a small-scale conical, cylindrical beam. The beam is constructed from functionally graded (FG) porosity-dependent material and operates under the thermal conditions of the environment. Imperfections within the non-uniform beam vary along both the radius and length direction, with continuous changes in thickness throughout its length. The resulting structure is functionally graded in both radial and axial directions, forming a bi-directional configuration. Utilizing the energy method, governing equations are derived to analyze the thermal stability and buckling characteristics of a nanobeam across different beam theories. Subsequently, the extracted partial differential equations (PDE) are numerically solved using the generalized differential quadratic method (GDQM), providing a comprehensive exploration of the thermal behavior of the system. The detailed discussion of the produced results is based on various applied effective parameters, with a focus on the potential application of nanotubes in enhancing sports bikes performance.

• Geomechanics and Engineering
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• v.29 no.6
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• pp.667-681
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• 2022

This paper presents a thermoelastic analysis of variable thickness plates made of functionally graded materials (FGM) subjected to mechanical and thermal loads. The thermal load is applied to the plate as a temperature difference between the top and bottom surfaces. Temperature distribution in the plate is obtained using the steady-state heat equation. Except for Poisson's ratio, all mechanical properties of the plate are assumed to vary linearly along the thickness direction based on the volume fractions of ceramic and metal. The plate is resting on an elastic foundation modeled based on the Winkler foundation model. The governing equations are derived based on the third-order shear deformation theory (TSDT) and are solved numerically for various boundary conditions using the differential quadrature method (DQM). The effects of various parameters on the stress distribution and deflection of the plate are investigated such as the value of thermal and mechanical loads, volume fractions of ceramic and metal, and the stiffness coefficients of the foundation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.172-178
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• 2017

Thermal property is one of the important characteristic in the field of energetic materials. As the energy material is released during decomposition, DSC(Differential Scanning Calorimetry) is frequently used for the thermal analysis. In case of the dynamic DSC measurements, thermal dynamic change like melting is prevented from the thermal property measurements. And due to the predicting kg scale, the conditions of the heat exchange with the environment significantly is changed. In this study, As the method to resolve the problem, we predict the thermal aging property using the AKTS thermokinetic program from DSC measurements which performed isothermal method. Predicting the thermal aging properties from ARC(Accelerating Rate Calorimetry) measurement, we compare two results.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.229-230
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• 2023

In this study, the hydration heat differential method was applied to mass concrete structures, and the hydration heat analysis was compared and analyzed with on-site measurement results. The results showed that the temperature history measurements of mass concrete were managed at a difference of 8.4 ℃, and although there was some deviation in thermal stress, a similar trend was observed. Consequently, it was determined that the thermal stress on the surface of mass concrete is less than its tensile strength, which would prevent the occurrence of thermal cracks.

• Journal of the Korean Ceramic Society
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• v.21 no.4
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• pp.349-354
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• 1984

The purpose of present study is to find the structure crystallization mechanism and physical properties in $TiO_2$ containing lead zinc borosilicate glass system. The experiments such as differential thermal analysis infrared spectral analysis. X-ray diffraction analysis and thermal expansion measurements have been done. Differential thermal analysis of coarse and fine glass powder showed bulk nucleating mechanism for high $TiO_2$ containing glasses and surface nucleation mechanism for low $TiO_2$ containing glasses. The prepared glasses crystallized to crystalline mixture of PbO.2ZnO. $B_2O_3$ .4PbO.2ZnO.$5B_2O_3$and 2PbO.ZnO.$B_2O_3$ when heat-treated in the range of 480 and 51$0^{\circ}C$ and crystallized to PbTiO3 when heat-treated at $600^{\circ}C$. Obtained crystalline phase of $PbTiO_3$ in glass matrix strongly affects to thermal expansion coefficient and the value of crystallized glass varied 68.0 to $107.1{\times}10-7$/$^{\circ}C$ depending on the amount of $TiO_2$added. Infrared spectral analysis showed that [$BO_3$] triangle and [$BO_3$] tetrahedral units were coexisted in the glass with high content of PbO.