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ASTM D5470 방법으로 연강과 스테인리스강의 열전도도 측정시 열그리스의 영향
조영욱,한병동,이주호,박성혁,백주환,조영래,Cho, Young-Wook,Hahn, Byung-Dong,Lee, Ju Ho,Park, Sung Hyuk,Baeg, Ju-Hwan,Cho, Young-Rae 한국재료학회 2019 한국재료학회지 Vol.29 No.7
Thermal management is a critical issue for the development of high-performance electronic devices. In this paper, thermal conductivity values of mild steel and stainless steel(STS) are measured by light flash analysis(LFA) and dynamic thermal interface material(DynTIM) Tester. The shapes of samples for thermal property measurement are disc type with a diameter of 12.6 mm. For samples with different thickness, the thermal diffusivity and thermal conductivity are measured by LFA. For identical samples, the thermal resistance($R_{th}$) and thermal conductivity are measured using a DynTIM Tester. The thermal conductivity of samples with different thicknesses, measured by LFA, show similar values in a range of 5 %. However, the thermal conductivity of samples measured by DynTIM Tester show widely scattered values according to the application of thermal grease. When we use the thermal grease to remove air gaps, the thermal conductivity of samples measured by DynTIM Tester is larger than that measured by LFA. But, when we did not use thermal grease, the thermal conductivity of samples measured by DynTIM Tester is smaller than that measured by LFA. For the DynTIM Tester results, we also find that the slope of the graph of thermal resistance vs. thickness is affected by the usage of thermal grease. From this, we are able to conclude that the wide scattering of thermal conductivity for samples measured with the DynTIM Tester is caused by the change of slope in the graph of thermal resistance-thickness.
송정빈,최윤혁,양동규,김영균,김성겸,최연석,이해근 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.5
This study investigates the thermal and electrical characteristics of a silicon-based grease insulation (GI) GdBCOcoil with respect to the winding tension through charge, sudden discharge, and over-current tests. Charge and suddendischarge test results demonstrate that the charging/discharging delay time increases as the winding tensionincreases; this is because the characteristic resistance of the coil decreases due to the reduced contact resistance. The over-current test results confirm that the thermal/electrical stabilities of the GI coil are considerably enhancedwith an increased winding tension resulting from improved thermal contact and the decrease in the electrical contactresistance between the turn-to-turn layers of the coil. Thus, as the winding tension increases, the charging/dischargingrates decrease whereas the thermal/electrical stabilities improve. Overall, selecting the appropriate windingtension for a GI coil is critical for achieving thermal/electrical stabilities, as well as ameliorating the charging/dischargingdelay phenomenon generally observed in a no-insulation coil.
펠티어 소자를 이용한 40[W]급 LED 조명기구의 방열에 관한 연구
어익수(Eo, Ik-Soo),양해술(Yang, Hae-Sool),최세일(Choi, Se-Ill),황보승(HwangBo, Seung) 한국산학기술학회 2007 한국산학기술학회논문지 Vol.8 No.4
본 논문은 MCPCB에 다수의 와트급 LED를 모듈화하여 조명기구로 사용함에 따라 발생하는 열을 해결하기 위한 제안이다. LED가 조명기구로 사용되려면 칩의 용량이 커야하며 이 결과 P-N접합부의 열이 증가하게 됨으로 이를 해결하기 위해 펠티어 소자와 방열판 그리고 Fan을 설치하여 온도변화특성을 측정하였다. 또한 부가적으로 냉각소자와 방열판을 접속하는 열전도판, 단열재, Themal Grease에 따른 온도변화특성을 실험하였다. 그 결과 방열판의 종류 및 체적에 따른 용도 변화가 가장 중요한 요소로 나타났다. Fan의 on, off에 따른 온도변화는 최대 18[℃]의 변화 폭을 주었으며 부가적 재료들도 2~3[℃]의 온도변화에 영향을 주어 무시할 수 없는 요소임을 확인하였다. The object of this paper is to propose a method to solve resulting heat in using numerous modulized watt-class LEDs in MCPCB as lighting device. To use LED for lighting, the chip needs to have a large capacity, resulting in extra heat in P-N connection area. To solve this problem, a Peltier Module, heat-sink panel and a fan was installed to measure variations in the temperature. Additionally, temperature variation characteristics were observed according to the heat conductor panel connecting cooling module and heat-sink panel, insulator and thermal grease. As a result, the type and amount of heat-sink panel was the most important factor. The fan would effect the temperature by max. 18[℃] while other materials affected the temperature by 2~3[℃], showing significant difference.
Graphene, Cu와 Ag 나노 파우더를 이용한 열전도재의 방열 특성에 관한 연
박상혁,임성훈,김현지,노정필,허선철 한국산업융합학회 2019 한국산업융합학회 논문집 Vol.22 No.6
The thermal diffusion performance of the electronic device is a factor for evaluating the stability of the electronic device. Therefore, many of research have been conducted to improve the thermal characteristics of thermal interface materials, which are materials for thermal diffusion of electronic products. In this study, nano thermal grease was prepared by blending graphene, silver and copper nano powders into a thermal grease, a type of thermal interface materials, and the heat transfer rate was measured and compared for the purpose of investigating the improved thermal properties. As a result, the thermal properties were good in the order of graphene, silver and copper, which is thought to be due to the different thermal properties of the nano powder itself
고열전도성 재료를 첨가한 서멀그리스의 열전달성능에 관한 연구
박상혁(Sang-Hyeok Park),백성미(Sung-Mi Back),양진호(Jin-Ho Yang),허선철(Sun-Chul Huh) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
The heat dissipation performance of the CPU package greatly affects the performance and lifetime of the CPU. Thermal grease is a kind of TIM, which removes the air layer between the heat spreader and the heat sink during the heat dissipation process of the CPU, so that the heat dissipation smoothly proceeds. However, if thermal grease with low heat transfer performance is used, heat dissipation rate is slowed down. In this study, thermal grease with high performance was prepared by mixing nanoparticles of graphene and metal with high thermal conductivity into thermal grease, and the heat transfer rate was measured. The results showed that the thermal grease mixed with graphene and silver was efficient and the thermal grease with graphene was the most efficient.
써멀 그리스의 열전달계수에 따른 CPU 온도변화에 관한 비교
심재웅,조홍종,조규창,곽준재,금성민 한국기계기술학회 2021 한국기계기술학회지 Vol.23 No.2
In this study, the effect of thermal grease and heat sink material of cooler on CPU temperature was measured and compared with LinX(v0.9.6) and HWMonitor.When the computer is booted without thermal grease applied, the CPU temperature rises rapidly, and the CPU temperature reaches 100℃ after 60 seconds for aluminum heat sink and 140 seconds for copper heat sink. The CPU temperature is lower as the thermal conductivity coefficient of thermal grease is higher, and the CPU temperature is lower when the thermal conductivity coefficient of the cooler is higher. In addition, when using a thermal grease and a heat sink with a high coefficient of thermal conductivity, the cooler rpm can be lowered, which is considered to be advantageous in terms of system stability and energy saving.
Review : Thermal contact problems at cryogenic temperature
Jeong, Sangkwon,Park, Changgi The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.4
This paper addresses technical problems of thermal contact conductance or resistance which inevitably occurs in most cryogenic engineering systems. The main focus of this paper is to examine what kind of physical factors primarily influences the thermal contact resistance and to suggest how it can be minimized. It is a good practical rule that the contact surface must have sub-micron roughness level with no oxide layer and be thinly covered by indium, gold, or Apiezon-N grease for securing sufficient direct contact area. The higher contact pressure, the lower the thermal contact resistance. The general description of this technique has been widely perceived and reasonable engineering results have been achieved in most applications. However, the detailed view of employing these techniques and their relative efficacies to reduce thermal contact resistances need to be thoroughly reviewed. We should consider specific thermal contact conditions, examine the engineering requirements, and execute each method with precautions to fulfil their maximum potentials.
CNT 열전달 물질에 의한 50W LED의 방열 성능평가
조영태(Young-Tae Cho),이충호(Choong-Ho Lee) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.6
In this study, cooling and heat-transfer tests are performed to compare and evaluate the thermal conductivity in a prepared CNT TIM (thermal interface material). A polymerized CNT heat-transfer resin and commercial thermal grease (Shinetsu G-747) were applied for a comparison test in both cases. Cooling experiments with an aluminum foil specimen were performed in order to measure the temperature distribution using an infrared camera, and in heat radiation experiments, performance testing of the thermal conductivity was conducted using high-power LEDs. Carbon resin with the polymerization of graphite and carbon black, and CNT-polymerized CNT resin with graphite and carbon black were tested and compared with using G-747. It was found that the cooling performance and the heat transfer ability in both the carbon resin and the CNT-polymerized CNT resin were greater than those of G-747 because the temperature by 5.0℃ in both cases appeared lower than that of the G-747.
강하늘(Haneul Kang),김현지(Hyunji Kim),김광수(Kwangsu Kim),임성훈,허선철(Sunchul Huh) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.7
Recently, as electronic devices and main boards have been miniaturized and increased in performance, the power density of emission has been rapidly increasing. In order to improve the heat dissipation performance of the electronic device, a heat conductive material having excellent internal heat dissipation performance is used. Accordingly, in this study, nickel nano thermal grease was prepared by mixing nickel nano powder used as a heat transfer medium with silicon oil. As a result, it improved by about 190% compared to silicone base oil.