• 대한기계학회논문집B
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• 제28권8호
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• pp.961-967
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• 2004

An inclined jet impinging on a pin fin heat sink is proposed and investigated experimentally. To investigate the flow pattern, flow visualization using fluorescence and velocity measurement using particle image velocimetry(PIV) are conducted with water. The jet impinges over a wide span of the heat sink with a large recirculation in the upper free space and occasionally with another smaller one in the upstream corner. Further, thermal experimentation is conducted using air to obtain temperature profiles using a thermocouple rake in the air and using thermal image on the heat sink back plate, with impinging angles of 35, 45 and 55 degrees. The Reynolds number range based on the nozzle slot is varied from 1507 to 6405. The results show that impinging angle of 55 degree shows the largest heat transfer capability. The results of thermal experiment are compared and discussed with those of flow visualization.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.192-193
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• 2000

We studied the characteristics and fabricated the plano-convex refractive microlenses using the thermal reflow method. The exposed resist was resolved in a standard developing process. The remaining resist of circle pattern was melted in an oven 12$0^{\circ}C$ to 15$0^{\circ}C$. The shape of the melted resist microlenses is ruled by surface tension. Diameter and hight of the fabricated microlenses were 250${\mu}{\textrm}{m}$ to 325${\mu}{\textrm}{m}$ and 15${\mu}{\textrm}{m}$ to 22${\mu}{\textrm}{m}$, respectively. The surface profile was calculated using data curve-fitting method with circle equation. The optical characteristics was analysed using optical simulation program.

• 한국태양에너지학회 논문집
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• 제28권1호
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• pp.75-81
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• 2008

Thermal performance of passive solar Trombe wall system which is applied on the south wall of KIER Zero energy Solar House has been monitored for 6 months of heating season. Based upon the long-term measurement results, extensive statistical analysis was conducted to investigate temperature profiler and heat flow pattern in Trombe wall system under actual operating condition. Heat flow characteristics depending on the time variation of day and month was clearly revealed. Heat gain and loss on the inner surface of the Trombe wall was calculated base upon measured temperature data. Those results would be utilized to improve the efficiency of new type solar storage wall system.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.253-258
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• 2007

Guss asphalt used in pavement of a steel deck bridge may cause severe stress and displacement on the bridge as it is treated using very high temperatures ranging from $220^{\circ}C$ to $260^{\circ}C$. Therefore, it is critical to estimate the thermal effect of Guss asphalt on the steel deck bridge before the width and pattern of the unit portion are decided to minimize impact. In this study, introduce a new analysis method styled the Heat source of equivalent of the cable stayed bridge were conducted to verify the feasibility of numerical value analysis by comparing the results with the data measured. The thermal effects of Guss asphalt on the steel deck bridge according to temperature changes were also studied.

• 한국지열·수열에너지학회논문집
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• 제6권1호
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• pp.17-22
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• 2010

A sliding accident on the road have a high percentage by road freezing, especially, it is often appeared at bridges and tunnel of freezing areas. Thus, the stability of road operations is enhanced by preventing a partial freezing phenomenon. According to the geothermal snow melting system analysis, a pattern of thermal conductivity is found out about pavement materials of concrete and asphalt when it is buried. For the feasibility study on geothermal snow melting system, analysis of the ground melting point when operating system, life evaluation of pavements and safety evaluation of pipes are performed.

• 대한기계학회논문집B
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• 제23권7호
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• pp.820-830
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• 1999

The coupled turbulent flow and solidification is considered in a typical slab continuous easting process using commercial program FIDAP. Standard $k-{\varepsilon}$ turbulence model is modified to decay turbulent viscosity in the mushy zone and laminar viscosity is set to a sufficiently large value at the solid region. This coupled turbulent flow and solidification model also contains thermal contact resistance due to the mold powder and air gap between the strand and mold using an effective thermal conductivity. From the computed flow pattern, the trajectory of inclusion particles was calculated. The comparison between the predicted and experimental solidified shell thickness shows a good agreement.

• 대한기계학회논문집B
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• 제32권12호
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• pp.931-937
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• 2008

A high motive pressure thermal vapor compressor(TVC) for a commercial multi-effect desalination(MED) plant is designed to have a high entraining performance and its robustness is also considered in the respect of operating stability at the abrupt change of the operating pressures like the motive and suction steam pressure which can be easily fluctuated by the external disturbance. The TVC having a good entraining performance of more than entrainment ratio 6.0 is designed through the iterative CFD analysis for the various primary nozzle diameter, mixing tube diameter and mixing tube length. And then for a couple of TVC having a similar entrainment ratio, the changes of the entrainment ratio are checked along the motive and suction pressure change. The system stability is diagnosed through the analyzing the changing pattern of the entrainment ratio.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.146-151
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• 2009

A Gaussian beam of single mode fiber laser was changed into a ring-shaped pattern after it was transmitted through the hollow optical fiber. The ring-shaped beam was focused on a plane by an f-. lens and it was scanned by a Galvano-mirror. The spatial profile of laser energy incident on a plane had two peaks at both sides of the scanned linear track. The profile was compared with the result obtained when the Gaussian beam was dithered transversely by an acousto-optic modulator. It is found that hollow optical fiber beam shaper can replace acousto-optic beam dithering device which is employed in a laser induced thermal printing system.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.361-366
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• 2013

An imaging technique to visualize the internal defects in a plate-type nuclear fuel specimen was developed by using an active optical interferometer for a nondestructive quality inspection. A periodic thermal wave having a sinusoidal intensity pattern induced a periodical strain variation for the specimen. The varying strain image was acquired using an optical laser interferometer. The strain distribution over the internal defects will be distorted in an acquired strain image because a part of the thermal wave will be reflected from these defects during propagation. In this paper, internal defects were efficiently visualized by sequentially accumulating the extracted defect components. The experimental results confirmed that the developed visualization system can be a valuable tool to detect the internal defects in plate-type nuclear fuel.

• 대한기계학회논문집A
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• 제25권6호
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• pp.988-995
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• 2001

Functionally graded materials(FGMs) are highlighted to be suitable for high temperature engineering due to their continuous distribution of material properties. In this paper, an optimal design is executed for determining the optimal material volume distribution pattern that minimizes the steady-state thermal stress of FGM heat-resisting composites. The interior penalty function method and the golden section method are employed as optimization techniques while the finite element method is used for thermal stress analysis. Through numerical simulations we suggest the volume fraction distributions that considerably improve initial thermal stress distributions.