• Journal of the Korean Society for Heat Treatment
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• v.30 no.6
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• pp.251-257
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• 2017

The effect of annealing temperature on the martensitic transformation behavior, tensile deformation chracteristics and shape recovery etc., has been studied in TiNi based shape memory ribbon fabricated by coldrolling of wire. TiNi based shape memory wire (${\phi}=500{\mu}m$) of which structure is intermetallic compound could be cold-rolled without process annealing up to the reduction rate in thickness of 50%, but a few cracks appear in cold-rolled ribbon in the reduction rate in thickness of 65%. The $B2{\rightarrow}R{\rightarrow}B19^{\prime}$ martensitic transformation or $B2{\rightarrow}B19^{\prime}$ martensitic transformation occurs in annealing conditions dissipating lattice defects introduced by coldrolling. However, in case of higher reduction rate or lower annealing temperature, martensitic transformation in cold-rolled and then annealed ribbons does not occur. The maximum shape recovery rate of cold-rolled ribbons with the reduction rate of 35 and 65% could be achieved at annealing temperatures of 250 and $350^{\circ}C$, respectively. The shape recovery rate seems to be related to the stress level of plateau region on stress-strain curve.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.6
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• pp.316-326
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• 2017

Commercial buildings and institutions are predominantly cooled, thereby dissipating excess heat to a vertical ground heat exchanger (VGHE), than heat extracted over an annual cycle. Surface waters, such as lakes and ponds, provide a cost-effective means of reducing the VGHE length, and in balancing the thermal loads to the ground. This paper presents the measurement and analysis of the cooling performance of ground-coupled heat pump (GCHP) system, using surface water heat exchanger (SWHE) submerged in an artificial pond. In order to measure the performance of the system, we installed monitoring equipment, including sensors, for assessing the temperature and power consumption, after which the operation parameters were determined. The results from the thermal performance test for the SWHE indicate that the temperatures at the outlet of the SWHE and within the pond were affected by outdoor air temperature. In addition, the results reveal similar variation trends on temperatures; however, the peak temperatures of the SWHE were somewhat greater than those of outdoor air, due to the thermal capacity of the pond. Analyzing the cooling performance over the measurement period, the average coefficient of performance (COP) of heat pump was found to be 5.71, while that for the entire system was 2.99.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.273-278
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• 2009

The experimental study is performed to investigate the optimum design of the system dissipating properly heat from the in-situ solar panel installed on site. For this purpose, six 12-Watts panels, which are set at the different conditions of the solar panels contained phase change material, changing the array of the aluminum fin and honeycomb at the back of the panel, are tested. PCM, which has $44^{\circ}C$ melting point, is chosen in this study. In order to enhance the thermal heat from the absorbed heat in PCM, finned aluminum plate is placed. Furthermore, Aluminum honeycomb is imbedded in the back container to find if it would improve the thermal conductivity of PCM. As a result, the solar panel, which is combined with honeycomb and outward fins with PCM instead of placing the fine inward, is showing the best performance in terms of controling panel temperature and efficiency.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.331-338
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• 2005

The rapid advances in high power light sources and arrays as encountered in incandescent lamps have induced dramatic increases in die heat flux and power consumption at all levels of high power LED packaging. The lifetime of such devices and device arrays is determined by their temperature and thermal transients controlled by the powering and cooling, because they are usually operated under rough environmental conditions. The reliability of packaged electronics strongly depends on the die attach quality, because any void or a small delamination may cause instant temperature increase in the die, leading sooner or later to failure in the operation. Die attach materials have a key role in the thermal management of high power LED packages by providing the low thermal resistance between the heat generating LED chips and the heat dissipating heat slug. In this paper, thermal transient characteristics of die attach in high power LED package have been studied based on the thermal transient analysis using the evaluation of the structure function of the heat flow path. With high power LED packages fabricated by die attach materials such as Ag paste, solder paste and Au/Sn eutectic bonding, we have demonstrated characteristics such as cross-section analysis, shear test and visual inspection after shear test of die attach and how to detect die attach failures and to measure thermal resistance values of die attach in high power LED package. From the structure function oi the thermal transient characteristics, we could know the result that die attach quality of Au/Sn eutectic bonding presented the thermal resistance of about 3.5K/W. It was much better than those of Ag paste and solder paste presented the thermal resistance of about 11.5${\~}$14.2K/W and 4.4${\~}$4.6K/W, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.11
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• pp.1087-1093
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• 2010

The satellite thermal control H/W composed of two parallel channels working for heat pipe (HP) and phase change material (PCM) is suggested for the high heat dissipating component which works intermittently with short duty. In a limited point of view, the HP-PCM device is a kind of off-the-shelf component that requires no dedicated configuration and thermal designs to PCM. Therefore, it can be used with less impact on the program cost and schedule different from most of the PCM applications. In present study the typical honeycomb structure radiator applying the HP-PCM device is designed and the detail thermal math model is developed for numerical analyses. The result comparison between without and with PCM shows that the HP-PCM device redistributes the peak heat around the whole mission period through the alternate melting and freezing of PCM, and, as a result, the maximum and minimum temperatures are effectively alleviated. The drawback of PCM application due to low thermal conductivity can be successfully resolved by means of parallel arrangement of HP channel.

• Journal of the Korean Institute of Oriental Medical Informatics
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• v.16 no.1
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• pp.9-73
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• 2010

This study is to focus on Ye Tian-Shi's Treatise on Externally Contracted Heat Disease Pattern Identification of warm disease as viewed through the concept of the various warm diseases characterized by rapid onset and shifts, pronounced heat signs, and a tendency to form dryness and damage eum. Finally, when it reaches blood and causes depletion and frenetic movement, treatment involves cooling and dissipating the blood." These lines represent the general outline of the four-aspect pattern identification and treatment system of the doctrine of warm diseases.

• Journal of the Korean Solar Energy Society
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• v.30 no.2
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• pp.10-15
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• 2010

The experimental study was conducted to optimize the system dissipating properly heat from the in-situ solar panel installed on the roof. For this purpose, six 12-Watt panels, which were consisted of the different design conditions such as containing phase change material(PCM), changing the array of the aluminum fin and honeycomb at the back of the panel, were tested. PCM, which had $44^{\circ}C$ melting point, was chosen in this study. In order to enhance absorbing and expelling heatin PCM, profiled aluminum fin was placed either inward oroutward from the panel. Furthermore, Aluminum honeycomb is imbedded in the back container to find if it would improve the thermal conductivity of PCM. During the experiment, there were ranged to $26^{\circ}C\sim32^{\circ}C$ for outdoor temperature and $700W/m^2\sim1000W/m^2$ for irradiance. As a result, the solar panel, combined with honeycomb and outward fins with PCM instead of placing the fins inward, is showing the best performance in terms of controling panel temperature and its efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.5
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• pp.521-528
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• 1992

this paper a new PAM-PWM Inverter using IGBT Is described. The output waveforms in the proposed PAM-PWM inverter are investigated both theoretiically and experimentally. The line-voltage waveform is composed of fundamental component and the sidebands of carrier frequency. The lower order harmonics are not included In the output waveform. As each inverter arm does not operate during two-thirds period, the heats, generated in the devices are reduced. That is the size of the inverter system can be minimized because of the reduction In the heat dissipating equipemnt.

• Korean Journal of Metals and Materials
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• v.46 no.9
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• pp.572-576
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• 2008

Elastostatic compression tests were carried out on amorphous alloys to evaluate their energy absorption capability during homogeneous deformation at room temperature. Experiments demonstrated that a compressive stress below the global yield imposed on amorphous alloys for extended periods causes homogeneous plastic strain associated with the irreversible structural disordering. During the disordering process, free volume was created, dissipating the externally applied strain energy and the rate of creation was found to converge to a saturated value. We evaluated the capability of energy absorption of amorphous alloys during homogeneous deformation using recent theories on the evolution of the structural state.

• Molecules and Cells
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• v.45 no.10
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• pp.673-684
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• 2022

The past two decades have witnessed an upsurge in the appreciation of adipose tissue (AT) as an immunometabolic hub harbouring heterogeneous cell populations that collectively fine-tune systemic metabolic homeostasis. Technological advancements, especially single-cell transcriptomics, have offered an unprecedented opportunity for dissecting the sophisticated cellular networks and compositional dynamics underpinning AT remodelling. The "re-discovery" of functional brown adipose tissue dissipating heat energy in human adults has aroused tremendous interest in exploiting the mechanisms underpinning the engagement of AT thermogenesis for combating human obesity. In this review, we aim to summarise and evaluate the use of single-cell transcriptomics that contribute to a better appreciation of the cellular plasticity and intercellular crosstalk in thermogenic AT.