• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.730-733
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• 2010

The Green Lamp Fixture (GLF) of LED prepared with thin panel structure was investigated for illumination of street lamps and other lighting system uses, which was also very useful to aquaculture and aquafarm lighting uses, or fish luring lights and marine aquanautics of aquamarinautics (aquamarine+aquanautics) uses, etc. In the case of fish luring lights, it was verified that the fish luring of Green Lamp Fixture of LED was very effective for phototaxis movement and ecological community promotion to the micro-living things of organisms and the small fries and fishes, like as 'crowding together'. For the aquaculture lightings, it was also very excellent in waterproof and heat-sink properties, photosynthetic growing of algae and micro-organisms, water-weeds and seaweeds living underwater.

• Solar Energy
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• v.17 no.3
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• pp.67-73
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• 1997

In order to development of a new wall structure type thermal diode for energy saving, the numerical studies have been performed for natural convection across an rectangular enclosure with the various lengthes of the heat source and sink plate. The governing equations for the two-dimensional, laminar, natural convection process in an enclosure are discretized by the control volume approach which insures the conservative characteristics to be satisfied in the calculation domain, and solved by a elliptic SIMPLE algorithm. The momentum and energy equations are coupled through the buoyancy term.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.09a
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• pp.121-145
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• 2001

Chip Size Packages (CSP) are now widely used in high speed DRAM. The major driving farce of CSP development is its superior electrical performance than that of conventional package. However, the power dissipation of high speed DRAM like DDR or RAMBUS DRAM chip reaches up to near 2W. This fact makes the thermal management methods in DRAM package be more carefully considered. In this study, the thermal performances of 3 type CSPs named $\mu-BGA$^{TM}$$ $UltraCSP^{TM}$ and OmegaCSP$^{TM}$ were measured under the JEDEC specifications and their thermal characteristics were of a simulation model utilizing CFD and FEM code. The results show that there is a good agreement between the simulation and measurement within Max. 10% of $\circledM_{ja}$. And they show the wafer level CSPs have a superior thermal performance than that of $\mu-BGA.$ Especially the analysis results show that the thermal performance of wafer level CSPs are excellent fur modulo level in real operational mode without any heat sink.

• Journal of Environmental Science International
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• v.14 no.3
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• pp.311-325
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• 2005

Elements of atmospheric environment, temperature, humidity and wind, at the compus of KNU(Kyungpook National University) were investigated by the observations. The observed data were compared with those of DWS (Daegu Weather Station). The simulations of wind field and dispersions of polluted gases were conducted by MUKLIMO under the various conditions. The results show that the atmospheric environment of KNU are suitable but the campus does not play role as a heat sink in the city. The simulations of wind field show the air flows and wind channels in the campus clearly. The exhausted gases by motor vehicles on the northside street of campus affect very much to the campus with $NW(300^{\circ})$ wind. The running cars in the campus are also pollute much on the campus with the various wind directions. The characteristics of environmental conditions, various meteorological fields, wind channels, and dispersion of exhausted gases at the campus of KNU were understood quantitatively in the study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1756-1762
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• 2002

To effectively meet current regulations on the exhaust emissions of diesel engine required to control the deterioration of air pollution in the whole world, this study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in IDI diesel engine. A method fur supplying water through the air intake system to reduce the exhaust emissions has been considered with other methods such as water introduction in the form of water-in-fuel emulsion or water injection directly into the combustion chamber, but it has not been studied about the effects of water on the combustion concepts and the characteristics of exhaust emissions in detail until now. In this study, the formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased by increasing water amount.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.116-116
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• 2010

진공 chamber에서 방전된 plasma 내부를 외부 view port를 통하여 확인하는 것은 극히 제한적이며 leak의 확률을 높이고 plasma의 균일한 방전을 방해한다. 이를 개선하기 위하여 내장형 무선 카메라를 chamber 내부에 위치한 후 고진공 영역에서 촬영을 시도하였으나 일반적인 CCD 카메라로는 촬영할 수 없다. 고진공 영역에서 카메라 내부온도의 급격한 상승이 원인으로 밝혀졌고 적정온도인 $45^{\circ}C$를 초과하여 최대 $96^{\circ}C$까지 4 min 이내에 상승함을 IR camera로 확인할 수 있었으며 이 때 카메라가 작동하지 않았다. 또한 카메라를 고진공 영역에서 촬영 및 녹화하기 위해서는 $46^{\circ}C$의 온도를 낮추어야 함을 진공해제 이후 내부온도가 $50^{\circ}C$로 감소하면서 내장형 무선 카메라가 다시 작동함으로 인해 알 수 있었다. 본 연구에서는 이를 해결하기 위하여 내장형 무선 카메라에 AM 변조 방식의 311 MHz RF remote controller를 장착하여 외부에서 선택적으로 ON/OFF 할 수 있도록 개조하였고 10 L chamber에서 150 L/sec TMP를 이용하여 10-6 Torr의 압력에서 성공적으로 녹화 및 촬영하였다. 또한 내장형 무선 카메라 내부의 반도체 회로 규격 및 발열량과 heat sink의 규격 (열전도도, 복사율)을 추가로 조사하였다. 분자유동 영역에서 열전달은 복사에 의한 영향이 대부분이므로 내장형 무선 카메라 내부 온도를 감소시켜 카메라의 작동 시간을 연장하기 위하여 내부 회로에 emissivity가 높고 전기전도도가 낮아 회로에 영향이 없는 박막을 회로에 증착시키는 추후의 연구가 필요하다.

• Journal of the Korean Ceramic Society
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• v.44 no.11
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• pp.622-626
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• 2007

Graphite is widely used in electronic industry due to its excellent electrical and thermal properties. However, graphite starts to oxidize around $400^{\circ}C$ that seriously degrades its properties. SiC coating can be applied to graphite foam to improve its high temperature oxidation resistance. In this research, SiC coating on graphite foam was made via preceramic polymer using a polyphenylcarbosilane. 20% of polyphenylcarbosilane in hexane solution was coated onto graphite by dip coating method. Thermal oxidation was carried out at $200^{\circ}C$ for crosslink of the preceramic polymer and the sample were pyrolysized at $800^{\circ}C{\sim}1200^{\circ}C$ under nitrogen to convert the preceramic polymer to SiC film. The microstructure of the SiC coating after pyrolysis was investigated using FESEM and oxidation resistance up to $800^{\circ}C$ was evaluated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.4
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• pp.121-129
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• 2014

This study was carried out to develop an efficient plant growth system that can be controlled by altering the wavelength and illumination using a LED module. If it is possible to develop a system that can be controlled in this manner, utilizing different characteristics in the meaningful wavelength band depending on the growth time or type of plant, the plant growth conditions can be optimized. In order to this, red, green, blue and white LEDs are arrayed in a rectangle, consisting of LED modules which can be combined with each other. Consequently, the array can be used to select the optimal light conditions with monochromatic red, green, blue and white LEDs, or mixed LEDs, for plant growth. Experiments on the characteristics of the wavelengths to evaluate the efficiency of the plant growth system were performed. The usefulness of the system was demonstrated through a cultivation test involving several special plants.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.5
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• pp.12-18
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• 1975

Triac phase controlled pre-regulator를 이용한 직류안정화전원에서 제어소자 전력소모를 촤소로 줄이기 위하여, 부하전류의 증가에 따라 제어소자 양단전압을 낮추어 주는 회로를 고안하여 부가하였다. 이렇게 하므로써 제어소자의 전력소모가 약 40%정도 감소되어 방열장치가 간단해지거나 전력용량을 증가할 수 있게 되었으며 열발산이 곤란한 monolithic I.C.화에 유용하도록 하였다. A method on minimizing the power dissipation in the control element of a series D.C. voltage regutator is devised. An additional control circuit which reduces the average voltage drop across the control element according to increasing the load current is attached :o the trial phase controlled pre-regulator system. It is verified that the power dissipation in the control element is reduced up to 40% by this. circuit arrangement. The heat sink system can be simplified and the capacity of tile handling power is also increased. It is expected that this circuit arrangement can be applied to I.C. fabrication.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.6
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• pp.331-337
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• 2013

An experimental study on the performance of a liquid electric component cooling system was performed. The thermal resistance and pressure drop at a heat sink were measured, for aluminum waterblocks with four different internal shapes, with either smooth surface, porous media filling, or with fins of 5 mm height, or of 7 mm height. The fins had 0.5 mm thickness, and the gap between the fins was 0.5 mm. The waterblock internal dimension was $36.5{\times}36.5{\times}7mm$. Compared with the waterblock with smooth surface, the thermal resistance reduction was 11%, 46%, and 42% for waterblocks with porous media filling, 5 mm, and 7 mm fins, respectively. A new dimensionless parameter was suggested to evaluate the waterblock performance, with the simultaneous consideration of thermal resistance and pressure drop. The performance of the waterblock with fins of 5 mm height was best by parameter.