• Structural Engineering and Mechanics
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• v.74 no.3
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• pp.425-434
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• 2020

The present paper is concerned at investigating the effect of hydrostatic initial stress, gravity and magnetic field in fiber-reinforced thermoelastic solid, with variable thermal conductivity. The formulation of the problem applied in the context of the three-phase-lag model, Green-Naghdi theory with energy dissipation, as well as coupled theory. The exact expressions of the considered variables by using state-space approaches are obtained. Comparisons are performed in the absence and presence of the magnetic field as well as gravity. Also, a comparison was made in the three theories in the absence and presence of variable thermal conductivity as well as hydrostatic initial stress. The study finds applications in composite engineering, geology, seismology, control system and acoustics, exploration of valuable materials beneath the earth's surface.

• Coupled systems mechanics
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• v.8 no.5
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• pp.415-437
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• 2019

The present research deals with two-dimensional axisymmetric deformation in transversely isotropic magneto thermoelastic solid with and without energy dissipation, with two temperature and time-harmonic source. The proposed model is helpful for finding the type of relations between mechanical and thermal fields as most of the structural elements of heavy industries are frequently related to mechanical and thermal stresses at a higher temperature. The Hankel transform has been used to find a solution to the problem. The displacement components, stress components, and temperature distribution with the horizontal distance in the physical domain are calculated numerically. The effect of time-harmonic source and two temperature is depicted graphically on the resulting quantities.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.19 no.2
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• pp.8-19
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• 2023

Hydronic heated road pavement (HHP) systems have well studied and documented by many researchers. However, most of the systems run on asphalt, only a few are tested with concrete, and there rarely is a comparison between those two common road materials in their heating and cooling performance. The aim of this study is to investigate the thermal performance of the HHP, such as heat dissipation performance in winter season while focusing on the surface temperature of the concrete and asphalt pavement. For preliminary study a small-scale experimental system was designed and installed to evaluate the heat transfer characteristics of the HHP in the test field. The system consists of concrete and asphalt slabs made of 1 m in width, 1 m in length, and 0.25 m in height. In two slabs, circulating water piping was embedded at a depth of 0.12 m at intervals of 0.16 m. Heating performance in winter season was tested with different inlet temperatures of 25℃, 30℃, 35℃ and 40℃ during the entire measurement period. The results indicated that concrete's heating performance is better than that of asphalt, showing higher surface temperatures for the whole experiment cases. However, the surface temperature of both concrete and asphalt pavement slabs remained above 0℃ for all experimental conditions. The heat dissipation performance of concrete and asphalt pavements was analyzed, and the heat dissipation of concrete pavement was greater than that of asphalt. In addition, the higher the set temperature of the circulating water, the higher the heat dissipation. On the other hand, the concrete pavement clearly showed a decrease in heat dissipation as the circulating water set temperature decreased, but the decrease was relatively small for the asphalt pavement. Based on this experiment, it is considered that a circulating water temperature of 20℃ or less is sufficient to prevent road ice. However, this needs to be verified by further experiments or computational fluid dynamic (CFD) analysis.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.87-92
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• 2016

The importance of heat dissipation for the electric device modules along the thickness direction is increasing. Two types of two-layered materials, metal-metal bonding and dielectric-metal bonding, have been fabricated by roll bonding process and a thermal diffusivity of the specimens was measured along the thickness direction. The thermal diffusivity of specimens with metal-metal bonding measured by light flash analysis (LFA) showed a same value independent on the direction of heat flow. However, the thermal diffusivity of specimens with dielectric-metal bonding showed a big difference of 17.5% when the direction of heat flow changed oppositely in the LFA process. The measured thermal diffusivity of specimens when the heat flows from metal to dielectric direction showed smaller value of 17.5% compared to the value when the heat flow from dielectric to metal direction. The difference in thermal diffusivity of specimens with dielectric-metal bonding dependence on direction of heat flow is due to the electron-phonon resistance that occurred transfer process of electron energy to phonon energy near the interface.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.331-337
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• 2022

Manufactured thermoplastic composite materials to replace the metal materials used as battery housing materials for electric vehicles with lightweight materials. As the matrix material, nylon 6 which is a polymer material was used. Boron Nitrate(BN), which has high thermal conductivity, was used to provide heat dissipation performance. The heat dissipation characteristics of the thermally conductive polymer composite material according to the BN content and particle size were analyzed. The thermal conductivity value increased as the filler content increased, and composite materials particle size of 60 to 70㎛ and BN content of 50%, the thermal conductivity was 1.4 W/mK. The larger the particle size, the wider the inter-particle interface contact surface, which means that a thermal path was formed. wider the interfacial contact surface between the particles, and the thermal path was formed. A battery housing was manufactured using the manufactured thermally conductive polymer composite material, and the temperature change during charging and discharging of the cell was observed, and the possibility as a substitute material for the battery housing was confirmed.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.1-10
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• 2021

Recently, electronic components are becoming smaller and highly integrated. As a result, electromagnetic interference (EMI) and heat generation problems must be solved simultaneously with a small area and thickness. Graphene composites and graphite composites are lightweight materials that can simultaneously solve EMI shielding and heat dissipation problems with excellent electrical and thermal conductivity. With the recent development of synthetic technology and composite manufacturing technology, the research to application of their composites is increasing. In this paper, we reviewed the latest researches on composite films of graphene and graphite for EMI shielding and heat dissipation.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.35-39
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• 2023

ESG (Environment, Social, Governance) has become a major guideline for many companies to improve corporate value and enable sustainable management. Among them, the environment requires a technological approach. This is because technological solutions are needed to reduce or prevent environmental pollution and save energy. Semiconductor package technology has been developed to better satisfy the essential roles of semiconductor packaging: chip protection, electrical/mechanical connection, and heat dissipation. Accordingly, technologies have been developed to improve heat dissipation effect, improve electrical/mechanical properties, improve chip protection reliability, stacking and miniaturization, and reduce costs. Among them, heat dissipation technology increases thermal efficiency and reduces energy consumption for cooling. Also, technology to improve electrical characteristics has had an impact on the environment by reducing energy consumption. Technologies that recycling or reducing material consumption reduce environmental pollution. And technologies that replace environmentally harmful substances contribute to environmental improvement, in particular. In this paper, I summarize trends in semiconductor package technologies to prevent pollution and improve environment.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.297-312
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• 2012

For future multi-core processors, 3D integration is regarded as one of the most promising techniques since it improves performance and reduces power consumption by decreasing global wire length. However, 3D integration causes serious thermal problems since the closer proximity of heat generating dies makes existing thermal hotspots more severe. Conventional air cooling schemes are not enough for 3D multi-core processors due to the limit of the heat dissipation capability. Without more efficient cooling methods such as liquid cooling, the performance of 3D multi-core processors should be degraded by dynamic thermal management. In this paper, we examine the architectural impact of cooling methods on the 3D multi-core processor to find potential benefits of liquid cooling. We first investigate the thermal behavior and compare the performance of two different cooling schemes. We also evaluate the leakage power consumption and lifetime reliability depending on the temperature in the 3D multi-core processor.

• Land and Housing Review
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• v.3 no.1
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• pp.83-88
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• 2012

In this study, physical characteristics of cement and/or concrete materials that are typically used for energy-foundation (EF) structures have been studied. The thermal conductivity and structural integrity of the cement-based materials were examined, which are commonly encountered in backfilling a vertical ground heat exchangers, cast-in-place concrete piles and concrete lining in tunnel. For this purpose the thermal conductivity and unconfined compression strength of cement-based materials with various curing conditions were experimentally estimated and compared. Hydration heat generated from massive concrete in the cast-in-place concrete energy pile was observed for 4 weeks to estimate its dissipation time in the underground. The hydration heat may mask the in-situ thermal response test (TRT) result performed in the cast-in-place concrete energy pile. It is concluded that at least two weeks are needed to dissipate the hydration heat in this case. In addition, a series of numerical analysis was performed to compare the effect of thermal property of the concrete material on the cast-in-place pile.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.19-25
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• 2014

In the LED lighting applications, because LED packages are the origin of heat generation, there are thermal design problem on heat sinks. In the thermal design, it is important to consider the total volume and the total weight of heat sink simultaneously. In this study, an Al 6063 heat sink was optimized using Computational Fluid Dynamics(CFD) simulation tool for the cooling of 30W LED module, and then the cooling performance and the total weight of heat sinks with Al 6063 and Thermal Conductive Polycarbonate(TCP) were compared under the same conditions. As the result of simulation, an Al 6063 heat sink was optimized with 22 ea. of fins and 1.6 mm of fin thickness. LED Junction Temperature of the TCP Heat Sink was $5.6^{\circ}C$ higher, but total weight of it was 47 % less than the Al 6063.