• Proceedings of the KSME Conference
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• 2000.04b
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• pp.353-358
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• 2000

This paper presents the experimental investigation about miniature heat pipe for notebook PC. The focus of analysis is the operating temperature not to exceed $65^{\circ}C$ maximum allowable CPU surface temperature. Copper is used to heat pipe material and brass is wick material, and working fluid is selected to water. This cooling system is heat spreader method using a aluminum plate, since this method is most commonly used. According to the present study, heat for 3mm heat pipe, 8W, and for 4mm heat pipe, 10W, is found to power dissipation limit respectively, Soon after this investigation, sufficient long term life test should be followed.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2286-2291
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• 2008

Some electronics component, which is adopted as components of antenna for radar or satellite system and used for amplifying signals to transmit, is accompanied by very significant heat dissipation levels because of the inefficiencies inherent in radio frequency wave generation. So, proper cooling performance for that system is base requirement for thermal design. On this paper, we applied heat spreading structures to reduce thermal density and find the optimum values of heat sink design factors through theoretically, numerically and evaluated by product test. As the results, the performance of the cooling system shows the propriety of cooling high density heat dissipation electronics components.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.99-104
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• 2001

Thermally induced vibration response of solar array is investigated. The solar array model consists of composite thin walled beam and solar blanket, spreader bar. The composite thin walled beam incorporates a number of nonclassical effects of transverse shear, primary and secondary warping, rotary inertia and anisotropy of constituent materials. The solar blanket is a membrane subjected to uniform tension in the z direction. The spreader bar is a rigid member. A coupled thermal structure analysis that includes the effects of structural deformations on heating and temperature gradient is investigated. A stability criterion given in parameters for establishes the conditions for thermal flutter.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.31-36
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• 2015

The demand for multi-functionality, high density, high performance, and miniaturization of IC devices has caused the technology paradigm shift for electronic packaging. So, thermal management of new packaged chips becomes a bottleneck for the performance of next generation devices. Among various thermal solutions such as heat sink, heat spreader, TIM, thermoelectric cooler, etc. on-chip liquid cooling module was investigated in this study. Micro-channel was fabricated on Si wafer using a deep reactive ion etching, and 3 different micro-channel designs (straight MC, serpentine MC, zigzag MC) were formed to evalute the effectiveness of liquid cooling. At the heating temperature of $200^{\circ}C$ and coolant flow rate of 150ml/min, straight MC showed the high temperature differential of ${\sim}44^{\circ}C$ after liquid cooling. The shape of liquid flowing through micro-channel was observed by fluorescence microscope, and the temperarue differential of liquid cooling module was measuremd by IR microscope.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.98.3-98
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• 1998

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.5
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• pp.235-240
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• 2013

Pure-carbon materials such as graphite, graphene, carbon nanotubes, and diamond have very high thermal conductivities. The reported thermal conductivity of graphene is in the range 3000~5000W/m-K at room temperature. Here, we developed graphene/cu foam hybrid type heat spreader to obtain higher thermal conductivity than Cu foam. Hybrid materials were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and thermal conductivity measurement system; LFA (Laser Flash Analysis @ LFA 447, NETZSCH). We suggest that excellent thermal properties of graphene/cu foam hybrid structures are beneficial for all proposed electrical applications and can lead to a thermal management application.

• Journal of Periodontal and Implant Science
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• v.47 no.5
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• pp.292-311
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• 2017

Purpose: Beyond the limited scope of non-specific polyclonal regulatory T cell (Treg)-based immunotherapy, which depends largely on serendipity, the present study explored a target Treg subset appropriate for the delivery of a novel epitope spreader Pep19 antigen as part of a sophisticated form of immunotherapy with defined antigen specificity that induces immune tolerance. Methods: Human polyclonal $CD4^+CD25^+CD127^{lo-}$ Tregs (127-Tregs) and $na\ddot{i}ve$ $CD4^+CD25^+CD45RA^+$ Tregs (45RA-Tregs) were isolated and were stimulated with target peptide 19 (Pep19)-pulsed dendritic cells in a tolerogenic milieu followed by ex vivo expansion. Low-dose interleukin-2 (IL-2) and rapamycin were added to selectively exclude the outgrowth of contaminating effector T cells (Teffs). The following parameters were investigated in the expanded antigen-specific Tregs: the distinct expression of the immunosuppressive Treg marker Foxp3, epigenetic stability (demethylation in the Treg-specific demethylated region), the suppression of Teffs, expression of the homing receptors CD62L/CCR7, and CD95L-mediated apoptosis. The expanded Tregs were adoptively transferred into an $NOD/scid/IL-2R{\gamma}^{-/-}$ mouse model of collagen-induced arthritis. Results: Epitope-spreader Pep19 targeting by 45RA-Tregs led to an outstanding in vitro suppressive T cell fate characterized by robust ex vivo expansion, the salient expression of Foxp3, high epigenetic stability, enhanced T cell suppression, modest expression of CD62L/CCR7, and higher resistance to CD95L-mediated apoptosis. After adoptive transfer, the distinct fate of these T cells demonstrated a potent in vivo immunotherapeutic capability, as indicated by the complete elimination of footpad swelling, prolonged survival, minimal histopathological changes, and preferential localization of $CD4^+CD25^+$ Tregs at the articular joints in a mechanistic and orchestrated way. Conclusions: We propose human $na\ddot{i}ve$ $CD4^+CD25^+CD45RA^+$ Tregs and the epitope spreader Pep19 as cellular and molecular targets for a novel antigen-specific Treg-based vaccination against collagen-induced arthritis.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1016-1021
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• 2011

The enhancement for cooling performance of heat sink is surely necessary to guarantee the performance of electronic products. So in this paper, the cooling performances of the aluminum heat sink with pulsating heat pipe(PHP) were investigated experimentally and numerically. The pulsating heat pipe was used as a heat spreader. Working fluid of PHP was R-22. Heat inputs were 30W, 60W, 80W and 100W, respectively. Heat sink was tested for forced convection conditions with air velocity of 1 ~ 4m/s. And CFD simulations were conducted for two different heat sinks. The results showed that the cooling performance of heat sink with pulsating heat pipe was higher than that of conventional heat sink. Therefore, the pulsating heat pipe can be a good tool to improve cooling performance of heat sink.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.410-415
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• 2018

Expanded graphite (EG)/Ag nanoparticle composites were synthesized by the chemical reduction of Ag ions, followed by the addition of expanded graphite into an Ag reducing solution. The prepared composites showed uniform dispersion of Ag nanoparticles on the surface of expanded graphite and exhibited relatively higher thermal conductivities than those of pure expanded graphite. In the case of 10% Ag content in the composite, the thermal conductivity in the thickness direction was 78% higher than the pure expanded graphite. We suggest that EG/Ag nanoparticle composites are a strong candidate for advanced heat spreading material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.158-163
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• 2013

In this paper, thermal analysis of heatsink for 30 W class Chip-on-Board (COB) LED light source is performed by using SolidWorks Flow Simulation package. In order to increase the convection heat transfer, number of fin and shape of the heatsink is optimized. Furthermore, a copper spread is applied between the COB LED light source and the heatsink to mitigate the heat concentration on the heatsink. With the copper spread, the junction temperature between the COB LED light source and the heatsink is $50.9^{\circ}C$, which is $5.4^{\circ}C$ lower than the heatsink without the copper spread. Due to the improvement of the junction temperature, the light output is improved by 5.8% when the LED light source is stabilized. The temperature difference between the simulation and measured result of the heatsink with the copper spread is within $2^{\circ}C$, which verifies the validity of the thermal design method using a simulation package.