As the demand for appropriate heat dissipation measures to improve product stability and performance continues to increase and product design becomes highly integrated, research to improve heat transfer performance while maintaining the same area or size is required. In this study, the sample-shaped aluminum plate was treated as upper-coating, and the thickness of the coating was divided into 1mm, 2mm, and 3mm, respectively, and the coating material was applied with silver, copper, and graphene. The temperature condition of the heat source was set to 473K, and heat dissipation analysis was performed under natural convection. The thermal performance was compared and analyzed through temperature distribution, flow velocity distribution, and heat flux, and it was confirmed that the high thermal conductivity of graphene compared to other materials had a dominant effect on the increase in the conduction heat transfer rate. And it was confirmed that the high surface temperature of the graphene coating also increased the heat transfer rate by convection, thereby enhancing the heat dissipation effect.

본 연구는 난방온실의 온도분포 균일화를 위한 기초자료 제공을 목적으로 온수난방 방식의 토마토 재배 온실 에서 난방실험을 통하여 난방배관의 표면온도와 실내기온 사이의 상관관계를 분석하고, 난방배관의 열전달특성 분석과 난방배관 배치의 개선을 통하여 난방배관 표면온도의 편차를 줄이고 균일도를 향상시키기 위한 방안을 도출하였다. 서로 다른 두 온실의 온도분포를 분석하여 최대편차와 균일도를 검토한 결과, 온수의 유량이 많고 난방배관의 길이가 짧게 배치된 온실의 온도편차가 작고, 균일도는 높은 것으로 나타났다. 또한 순환팬을 가동한 경우에 온도편차는 작아지고 균일도가 개선되는 것을 확 인할 수 있었다. 난방배관의 표면온도와 실내기온 사이의 상관관계를 분석한 결과, 두 온실 모두에서 유의적인 (p<0.01) 정적 상관관계가 있는 것으로 나타났다. 온수난방 온실에서 실내기온의 분포는 난방배관 표면온도의 분포에 영향을 받는다는 것을 확인할 수 있었고, 온도편차 가 최소화 되도록 난방배관을 배치함으로써 실내기온 분포의 균일도를 개선할 수 있는 것으로 판단되었다. 난방 배관의 열전달 특성을 분석한 결과 배관의 길이가 길어 지면 온도편차는 커지고, 관내의 유속이 빨라지면 온도 편차는 작아지는 것으로 나타났다. 따라서 지선배관의 길이가 짧아지도록 난방배관을 배치하고, 관내의 유속을 제어함으로써 온실의 온도분포와 환경의 균일성을 개선 할 수 있을 것으로 판단되었다. 국내 온실에서 가장 많 이 사용하고 있는 튜브레일(40A) 방식의 온수난방시스 템에서 하나의 지선배관에서의 온도편차를 3oC 이내로 조절하기 위해서는 관내의 유속이 0.2, 0.4, 0.6, 0.8, 1.0m·s-1일 때 난방배관의 길이는 각각 40, 80, 120, 160, 200m 이내로 제한해야 하는 것으로 분석되었다.

The purpose of this study is to provide basic data for setting environmental design standards for domestic greenhouses. We conducted experiments on thermal environment measurement at two commercial greenhouses where hot water heating system is adopted. We analyzed heat transfer characteristics of hot water heating pipes and heat emission per unit length of heating pipes was presented. The average air temperature in two greenhouses was controlled to 16.3oC and 14.6oC during the experiment, respectively. The average water temperature in heating pipes was 52.3oC and 45.0oC, respectively. Experimental results showed that natural convection heat transfer coefficient of heating pipe surface was in the range of 5.71~7.49W/m2 oC. When the flow rate in heating pipe was 0.5m/s or more, temperature difference between hot water and pipe surface was not large. Based on this, overall heat transfer coefficient of heating pipe was derived as form of laminar natural convection heat transfer coefficient in the horizontal cylinder. By modifying the equation of overall heat transfer coefficient, a formula for calculating the heat emission per unit length of hot water heating pipe was developed, which uses pipe size and temperature difference between hot water and indoor air as input variables. The results of this study were compared with domestic and foreign data, and it was found to be closest to JGHA data. The data of NAAS, BALLS and ASHRAE were judged to be too large. Therefore, in order to set up environmental design standards for domestic greenhouses, it is necessary to fully examine those data through further experiments.

LED (Light Emitting Diode) 조명은 차세대 조명으로 주목 받고 있으나 조명에서 방출되는 열에 의해 조명의 수명이 상당히 단축되는 문제가 있다. 이를 해결하기 위해 Al, Al-Zn 합금, Mg 합금 등의 열 전도성과 가벼운 재료를 heatsink로 사용되고 있다. 하지만 출력이 높고, 사용되는 조명의 수가 많을수록 heatsink의 크기가 커져야 하는 문제가 있다. 이를 해결하기 위해 본 연구에서는 heatsink 표면의 방열 성능을 향상시키기 위해 spray coating 방식에 비해 도막 형성이 균일한 전착도장 (electrodeposiion coating) 방식의 도료를 합성하였다. 열전도도를 향상시키기 위해 전도성 구형 안료와 침상 안료를 사용하였고, 이를 비교하기 위해 heatsink의 온도 변화를 측정하였다. 그리고 도막의 표면을 Scanning Electron Microscope를 통해 관찰 하였다. 안료의 첨가에 따라 코팅막에 복잡한 구조가 만들어졌고 열을 전도할 수 있는 경로를 제공하여 방열 성능이 향상됨을 확인하였다.

본 연구에서는 DVR 내부 공기유동을 직접 제어하여 CPU의 온도를 낮추기 위한 유동제어 구조물을 제안하였다. 제안된 구조물은 세 개의 얇은 판의 형태로 구성되었으며, DVR 내부의 공기 유동을 포괄적으로 제어하여 CPU의 효율적인 방열을 유도하고자 하였다. DOE와 RSM을 이용한 매개변수 연구기법을 통해 유동제어 구조물의 형상을 최적화하였으며, 해석에는 유한체적방법을 이용한 유체역학 분석 패키지인 FlowVision을 사용하였다. 실제 DVR 기기에서의 실험을 통해 해석 결과를 검증한 결과 CPU의 온도가 16.1℃ 낮아짐을 확인하였다

In this study, we analyzed the radiant heat performance of ballast fin when the aspect ratio of the fin of ballast was changed. The minimum size of the mesh was 0.02 mm, and the grid number was about more than 11 thousand. In order to analyze the radiant heat performance of ballast fin, the aspect ratio of fin was 1.00(2 mm:2 mm), 1.80(1.5 mm:2.7 mm), and 0.56(2.7 mm:1.5 mm) respectively; that the heat transfer area was constantly 0.4 mm 2 . The numerical condition was that heat flux was constantly 1×10 5 W/m 2 , and measuring times were 0.1 second, 0.2 second, 0.5 second, 2 seconds, 5 seconds and 10 seconds respectively. The temperature values of fin at the 1.00 and 1.80 of aspect ratios were extremely large when heat flux time was 10 seconds. As a result, the maximum value of radiant heat performance of ballast fin appeared to the aspect ratio of 1.80.

Various morphologies of copper oxide (CuO) have been considered to be of both fundamental and practical importance in the field of electronic materials. In this study, using Cu (0.1 μm and 7 μm) particles, flake-type CuO particles were grown via a wet oxidation method for 5min and 60min at 75 oC. Using the prepared CuO, AlN, and silicone base as reagents, thermal interface material (TIM) compounds were synthesized using a high speed paste mixer. The properties of the thermal compounds prepared using the CuO particles were observed by thermal conductivity and breakdown voltage measurement. Most importantly, the volume of thermal compounds created using CuO particles grown from 0.1 μm Cu particles increased by 192.5% and 125 % depending on the growth time. The composition of CuO was confirmed by X-ray diffraction (XRD) analysis; cross sections of the grown CuO particles were observed using focused ion beam (FIB), field emission scanning electron microscopy (FE-SEM), and energy dispersive analysis by X-ray (EDAX). In addition, the thermal compound dispersion of the Cu and Al elements were observed by X-ray elemental mapping.

Composite materials consisting of pure aluminum matrix reinforced with different amounts of graphite particles are successfully fabricated by mechanical ball milling and spark plasma sintering (SPS) processes. The shrinkage rates of the composite powders vary with the amount of graphite particles and the lowest shrinkage value is observed for the composite with the highest amount of graphite particles. The current slopes of time increase with increase in the amount of graphite particles whereas the current slopes of temperature show the opposite trend. The highest thermal conductivity is achieved for the composite with the least amount of graphite particles. Therefore, the thermal properties of the composite materials can be controlled by controlling the amount of the graphite particles during the SPS process.

The study will design the structural optimization of 30W LED heat sink using the thermal conductive plastic materials. The advantages of thermal conductive plastic heat sink are having formability and being able to lighten products. A heat sink was optimized in terms of the number, and the thickness of fins and the base thickness of the heat sink, using the Heatsinkdesigner software. Also by using SolidWorks Flow simulation and thermal analysis software, the thermal characteristics of the heat sink were analyzed. As the result, the optimized heat sink has 22 fins, which are 1.5mm thick and a 3.8mm-thick base. The weight of the heat sink was 310g, and the highest and the lowest temperature were 64.93℃ and 45.96℃ respectively. Because of the low thermal conductivity of the thermal conductive plastic, the highest and the lowest temperature of the thermal conductive plastic heat sink were 14.3℃ higher and 2.19℃ lower respectively than an aluminum heat sink

In this study, the control of microstructure for increasing surface roughness of Al with an electro-chemical reaction and a post treatment is systematically investigated. The Al specimen is electro-chemically treated in an electrolyte. In condition of the post treatment at 100oC for 10 min, a change of the surface microstructure occur at 50V (5 min), and a oxidized layer is at 400V, to which lead a decreasing surface roughness. The minimum temperature of the post treatment for a change of microstructure is 80oC. Moreover, in the condition of 300V (5 min), the electro-chemical reaction is followed by the post treatment at 100oC, the critical enduring time for the change of microstructure is 3 min. The longer post treatment time leads to the rougher surface. The treated Al specimen demonstrate better heat release ability owing to the higher surface roughness than the non-treated Al.

This study analyzed the thermal properties of a thermal conductive polymer polyethylene terephthalate(PET) to make it into a heat sink and evaluated the temperature properties of 10W COB(chip on board) LED(Ligth Emitting Diode) as a heat sink. This study confirmed the composition and content of inorganic compounds in PET. As a result, carbon filler content of Samples A and B accounted for 73.93 and 61.46%, respectively. Sample B included 10% more inorganic filler(Al, Mg, Si, Ca), and its thermal conductivity was 10.9 W/mk higher than Sample A. Based on the material properties, this study compared the heat dissipation properties of 10W COB LED between PET and aluminum heat sinks. As a result, the maximum temperature of PET heat sink was 4.4℃ higher than that of aluminum heat sink, and the minimum temperature outside PET heat sink was 13.6℃ lower than that of aluminum heat sink. Based on these results, PET heat sinks are inferior to aluminum heat sinks in thermal properties. However, it is considered possible to realize various designs because they have excellent formability and lightweight properties due to the lower melting point and specific gravity

본 논문에서는 액화천연가스 운송을 위해 사용되는 맴브레인형 Mark Ⅲ 화물창 시스템의 주요 구조물인, 방열 판 구조물의 파손 강도 평가를 수행한 내용을 다루고 있다. Mark Ⅲ 방열 판 구조물을 복합적층 구조물로 고려하였으며 상용화된 범용 유한요소 프로그램인 MSC사의 PATRAN과 MARC를 사용하여 Mark Ⅲ 방열 판 구조물의 유한요소 모델을 개발하였다. 특히, 액화천연가스 화물의 특성으로 인해 Mark Ⅲ 방열 판 구조물이 접하는 상온에서 극저온에 이르는 광범위한 온도분포에 따른 재료 물성치 변화를 유한요소 모델에 포함하였다. 이 유한요소 모델을 기반으로 파손 강도 평가 절차가 확립되었으며, 이 때 Mark Ⅲ 방열 판 구조물의 파손 발생 여부를 판단하기 위해 Hashin, Hill, Hoffman, maximum stress, 그리고 Tsai-Wu와 같은 이방성 파손 기준들을 사용하였다. Mark Ⅲ 방열 판 구조물의 전반적인 구조적 거동을 이해하였으며 이후 초기 파손 영역에서 강도 평가를 수행하여 파손이 발생되었을 때의 위치와 하중 등을 알 수 있었다.

LNG 방열 시스템의 선형 동적해석 모델을 사용하여 슬로싱 충격 압력을 구조해석에 적용 시 사용되는 이상화된 삼각파 압력에 대해서 검토하였다. 삼각파 압력의 최대값, 지속시간, 비대칭성의 충격파에 대한 구조 안전성 평가를 위해서 멤브레인 구조의 허용기준과 슬로싱 압력에 관련된 간략화된 파괴압력에 대해 검토하고, 슬로싱 충격 압력의 지속시간과 비대칭성으로 특징 지워진 이상화된 삼각파 형상의 압력을 고려한 일련의 선형 동적해석을 수행하여 설계기준으로 사용할 파괴압력을 도출하였다. 본 논문에서 제시한 방법을 통해서 방열시스템 구조 요소의 안전성을 평가하기 위한 파괴 압력을 선정할 수 있고 모형실험을 통한 슬로싱 압력과의 비교를 통하여 방열시스템의 구조안전성을 평가할 수 있을 것이라 판단된다. 또한 해석결과를 통해 방열시스템에서의 최대 응력은 매우 짧은 순간의 충격하중 하에서는 압력의 비대칭성 보다는 하중 지속시간에 많은 영향을 받고 있음을 검토하였다.

LED industry in the world, is rapidly emerging as an important policy means of each countries for climate change, saving energy and international environmental regulations. And incandescent bulb regulatory policy in each country is the role of growth catalysts for the LED lamp industry, it is expected to increase research and investment for the LED package in the future. However, In spite of the growth of the LED lamp industry, the price of the world LED lamp has been declining more than 30% per year and it is accelerating further. Therefore, an alternative techniques for high performance and cost reduction of the LED lamp has been studied. In this study, we studied the aluminum extrusion product inserted heat sink as a one of the alternative techniques which can improve the thermal efficiency and reducing costs. As a result, radiant heat effect was improved around 44.5% higher than the thermally conductive resin heat sink

This research is to investigate the cooling performance analysis of the heat sinks for LED light with four different fin types and two different fin numbers (16EA and 64EA) of heat sinks. Temperature distributions of fins over the flow domain are numerically calculated for the optimum design of heat sink fin types with uniform initial temperature of the bottom of the fins. According to the calculations of convective heat transfer coefficient between fin and atmosphere in the flow domain, S-curve fin type of heat sinks with 64EA of fins reveals the highest cooling performance of the heat sink fin types in the present cooling heat sink model.

In this study, the heat flow analysis compatible commercial code CFX 11 was used to develop the structure inside PCB circuit board devices, which could stable radiant heat as well as the cooling device within it. In case of modifying the arrangement of electronic parts on the PCB inside the multi channel temperature measurement board devices, radiant heat effects did not show a rising tendency, whereas the overall temperature went down in case of installing the vents in the outer case of PCB circuit board devices. In terms of installation location, it was the most appropriate to install it on the electronic parts with no heat. Besides, in case of mounting the fan as a cooling device by considering various user environments for multi channel temperature measurement board devices, the radiant heat effects were shown higher than in case of installing the vents, and the middle sections were the most appropriate to its installation location. In case of changing the wind quantity of the fan from its selected installation location, the best radiant heat effects were shown at high speed as expected.