• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.264-269
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• 2007

The microchannel waterblock has a good capability in the cooling of electronic devices. The object of this paper is to study on thermal performance of microchannel water block for cooling of CPU in desktop. The effects of header shape, liquid flow rate, and inlet temperature on the thermal performances of microchannel waterblock are investigated experimentally. Three types of waterblock with different header shape are manufactured from the micro milling and brazing processing. The experiments are conducted using water, over a liquid flow rate ranging from 0.7 to 2.0 LPM and inlet temperature ranging from 20 to $35^{\circ}C$. Waterblocks are attached both horizontally and vertically on the test section to anticipate a performance of waterblock under the actual state in computer. The base temperature and thermal resistance decrease with increasing of liquid flow rate. It was found that the sample #1 was appropriate for the prototype of liquid cooling system.

• 한국가시화정보학회지
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• 제1권1호
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• pp.75-81
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• 2003

A custom micro-PIV optics assembly has been used to measure the flow fold inside a T-junction of a microchannel. The micro-PIV system consists of microscope objectives of various magnifications, a dichroic cube, and an 8-bit CCD camera. Fluorescent particles of diameters 620 nm have been used with a Nd:YAG laser and color filters. A programmable syringe pump with Teflon tubings were used to inject particle-seeded distilled water into the channel at flow rates of 2.0, 4.0, 6.0 mL/hr. The micro-channels are fabricated with PDMS with a silicon mold, then O$_{2}$ -ion bonded onto a slide glass. Results show differences in flow characteristics and resolution according to fluid injection rates, and magnifications, respectively. The results include PIV data with vector-to-vector distances of 2 $\mu$m with 32 pixel-square interrogation windows at 50$\%$ overlap.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.84-87
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• 2007

Recently, many studies concern on the slip flow and slip length, which allow liquid flow to reduce drag force in microchannel. However, until now not enough investigation is performed experimentally to understand the slip flow in the superhydrophobic microchannel exhibiting riblet structures on vertical wall. Here we investigated and compared the slip flows according to the surface characteristics; hydrophilic, hydrophobic, and superhydrophobic wettabilities. Using the micro-PIV, velocity profiles can be obtained in the glass (hydrophilic), PDMS (hydrophobic), and micro-structured PDMS (superhydrophobic) microchannels. For both PDMS and superhydrophobic PDMS microchannels, we observed the slip effects showing the microscale slip lengths. Due to the micro-riblet, there are two distinctive flow characteristics on the riblet surface and the liquid meniscus in the valleys.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.423-426
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• 2002

A custom micro-PIV optics assembly has been used to measure the flow field inside a T-shaped microchannel. The micro-PIV system consists of microscope objectives of various magnifications, a dichroic cube, and an 8-bit CCD camera. Fluorescent particles of diameters 620nm have been used with a Nd:YAG laser and color filters. A programmable syringe pump with Teflon tubings were used to inject particle-seeded distilled water into the channel at flow rates of $420,\;40,\;60{\mu}L/hr$. The microchannels are fabricated with PDMS with a silicon mold, then $O_2-ion$ bonded onto a slide glass. Results show differences in flow characteristics and resolution according to fluid injection rates, and magnifications, respectively. The results show PIV results with vector-to-vector distances of $2{\mu}m$ with 32 pixel-square interrogation windows at $50{\%}$ overlap.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1004-1009
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• 2003

Electroosmotic flow induced by an applied electrostatic potential field in microchannel is analyzed in this study. The electroosmotic flow is an alternative to pressure driven flow in microchannels, but the usage has been limited to the simple cases. In this study, We analyze electroosmotic flow driven by inhomogeneous surface charge on the channel wall. The surface charge varies along a direction perpendicular to the electric field in order to generate the electroosmotic flow. A numerical results substantiate the highly efficient mixing performance. It is highly the beneficial to fabrication process since only straight microchannel rather than complex geometry is enough to yield efficient mixing.

• 한국가시화정보학회지
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• 제4권2호
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• pp.32-36
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• 2006

Recently there are many researches about single flow and two-phase flow phenomena in the mini and microchannel. But from this result the principle in the microchannel was not explained clearly. In this paper two-phase flow pattern was visualized in the micro-multi-branched-channel using a high speed camera. Microchannel was fabricated with PDMS and glass slide. The velocity profile was obtained by a Micro PIV. Then flow boiling at the near inlet area was occurred and vapor was moved in the micro-multi-branched-channel.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.62.2-62.2
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• 2005

• Nuclear Engineering and Technology
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• 제56권8호
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• pp.3030-3042
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• 2024

Steel containment vessels for nuclear power plants can experience gas leakage due to minute defects such as cracks, corrosion, and aging, leading to gas leakage. A gas leakage model for microchannels is established to elucidate the mechanism underlying gas leakage within microchannels caused by these defects, specifically addressing the issue of unidirectional gas flow. Computational Fluid Dynamics (CFD) and the UK R6 method are employed to calculate the gas leakage rate within microchannels. Furthermore, the characteristics of gas flow within microchannels are explored, including the factors affecting the gas leakage rate. Validation of the calculation results is verified experimentally. The results indicate that the gas mass flow rate exhibits a linear decrease with decreasing internal pressure and a non-linear decline as temperature increases. Additionally, the gas mass flow rate demonstrates a negative correlation with the microchannel length but a positive association to its hydraulic diameter. The primary influencing factors on gas leakage rates are hierarchically ranked as follows: pressure difference, microchannel cross-sectional area, temperature, microchannel length, and microchannel hydraulic diameter.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.80-83
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• 2004

This experiment has been carried out to measure the process of droplet formation between water phase fluid$(PVA\;3\%)$ and organic phase fluid(oil), Internal and External flow fields measured by a Dynamic Micro-PIV method Water-in-oil(W/O) droplets successfully generated at a cross junction and Y junction. Internal and external flow fields were measured when the droplet grew up, stretched and separated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.88.1-88.1
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• 2005