• Journal of the KSME
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• v.54 no.5
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• pp.32-35
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• 2014

이 글에서는 최근 자동차 및 가정용 공조기의 증발기로 널리 사용되고 있는 알루미늄 마이크로 채널 열교환기 내의 냉매분배 특성과 그의 개선 방안에 대하여 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.891-896
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• 2011

In this study, experiments were carried out to investigate the convective heat transfer characteristics of rectangular microchannels. The sample used in the experiments contained 20 rectangular microchannels in parallel. The channels had a hydraulic diameter of 700 ${\mu}m$. Distilled water was used as the working fluid. In the experiments, the Reynolds number ranged from 400 to 800, heat flux ranged from 35 to 85 kW/$m^2$, and the inlet fluid temperature was $20^{\circ}C$. As a result, the convective heat transfer coefficient increased upon increasing the Reynolds number and ranged from 4.6 to 6.4 kW/$m^2/^{\circ}C$ in the thermally fully developed region. Moreover, the higher the Reynolds number, the longer the thermal entry length in the rectangular microchannels. However, it was observed that a variable heat flux did not affect the thermal entry length. In conclusion, a correlation was proposed to indicate the heat transfer characteristics in a thermally fully developed region.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1032-1038
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• 2014

In this study, an experimental study was performed to understand the boiling heat transfer characteristics of FC-72 in parallel micro-channels. The parallel micro-channels contained channels having a $0.2mm{\times}0.45mm$ [$H{\times}W$] cross section and length of 60 mm. And heat flux was varied from 16.4 to $25.6kW/m^2$ and mass fluxes from 300 to $500kg/m^2s$. The measured heat transfer coefficient was sharply decreased at lower vapor quality and then it was kept approximately constant as the vapor quality is increased. From the experimental results, the boiling heat transfer mechanism of FC-72 was confirmed and the measured heat transfer coefficient was compared and analyzed with the existing correlations to predict the heat transfer coefficient.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.245-245
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• 2004

최근 급속히 성장하는 제약산업 분야에서 신약개발, 약물 투여, 유전자 분석에 필요한 비용과 시간을 줄이기 위하여 랩온어칩(Lab-on-a-chip) 기술이 부상하고 있다. 이러한 랩온어칩에서는 원하는 소량의 시료를 정밀하게 이송시켜 혼합, 반응, 분리, 검출 등이 하나의 칩 위에서 일련의 과정으로 수행 가능하게 하여 고속, 고효율, 저비용의 자동화를 시킬 수 있는 장점이 있다. 즉, 이는 하나의 칩 위에 분석에 필요한 여러 가지 장치들을 마이크로 머시닝 기술로 초소형 집적화 시킨 마이크로 프로세서이다.(중략)

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1929-1931
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• 2003

본 연구에서 제안하는 마이크로 밸브는 열공압 방식으로 구동되고 제작비용이 저렴한 indium tin oxide (ITO) 및 polydimethylsiloxane (PDMS)로 제작되었다. 제안된 마이크로 밸브의 구조는 ITO 히터, SU-8 층, PDMS membrane, 그리고 PDMS 채널로 구성되어 있다. 제작된 열공압 구동기의 PDMS membrane의 변위는 현미경의 초점 거리의 변화로 측정하였으며 히터에 160mW 전력 인가 시 변위는 대략 $132{\mu}m$이다. 마이크로 밸브의 히터에 인가 전력에 따른 유량측정은 DI water를 사용하여 측정하였고 inlet 압력은 1.2kpa를 인가하여 측정하였다. 히터 인가 전력이 영일 경우 채널 폭이 $200{\mu}m$와 $400{\mu}m$인 마이크로 밸브의 유량은 각각 대략 $36{\mu}{\el}$/min과 $110{\mu}{\el}$/min 이었다. 채널 폭이 $200{\mu}m$와 $400{\mu}m$인 마이크로 밸브의 유량은 히터 인가 전력이 각각 70mW와 160mW에서 영이 되었다.

• Journal of the Korean Vacuum Society
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• v.16 no.1
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• pp.65-73
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• 2007

The control of surface properties and spatial presentation of functional molecules within a microfluidic channel is important for the development of diagnostic assays, microreactors, and for performing fundamental studies of cell biology and fluid mechanics. Here, we present soft lithographic methods to create robust microchannels with patterned microstructures inside the channel. The patterned regions were protected from oxygen plasma by controlling the dimensions of the poly(dimethylsiloxane)(PDMS) mold as well as the sequence of fabrication steps. The approach was used to pattern a non-biofouling polyethylene glycol(PEG)-based copolymer or the polysaccharide hyaluronic acid(HA) within microfluidic channels. These non-biofouling patterns were then used to fabricate arrays of fibronectin(FN) and bovine serum albumin(BSA) as well as mammalian cells.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.78.2-78.2
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.53-59
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• 2010

In this paper, we propose a novel chaotic micromixer of which mixing mechanism is based upon magnetohydrodynamic (MHD) multi-vortical flow generation in a simple straight microchannel. In the microchannel of the micromixer has electrodes patterned on two side walls and bottom wall. Lorentz forces are variously induced by changing applied voltages at the patterned electrodes in order to pump and mix conductive fluids in the microchannel. Three-dimensional computational fluid dynamics simulations were conduced to characterize mixing behaviors inside the MHD micromixer. The mixing efficiencies were also evaluated for the various flow conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.823-829
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• 2014

In the present study, simple models were proposed to predict the capillary-driven flow length in a surfactant-added poly(dimethylsiloxane) (PDMS) rectangular microchannel. Owing to the hydrophobic nature of PDMS, it is difficult to transport water in a conventional PDMS microchannel by means of the capillary force alone. To overcome this problem, microchannels with a hydrophilic surface were fabricated using surfactant-added PDMS. By measuring the contact angle change on the surfactant-added PDMS surface, the behavior was investigated to establish a simple model. In order to predict the filling length induced by the capillary force, the Washburn equation was modified in the present study. From the investigation, it was found that the initial rate-of-change of the contact angle affected the filling length. Simple models were developed for three representative cases, and these can be useful tools in designing microfluidic manufacturing techniques including MIcroMolding In Capillaries (MIMIC).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.220-223
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• 2006

In this paper, we studied about the level controller of optical signal with 40 channels by 4 VOA(Variable Optical Attenuator) with 12 channels. Total 8 microprocessors control 40 chamois for control of optical signal level so that a microprocessor controls 5 channels each. Moreover a microprocessor was added to communicate with outside and transfer instruction to each microprocessor. The output optical signal is measured and VOA is controlled as a result of it. The VOA outputs is inputted into PD(Photo Detector) at once. We could control multi-channel optical signals simply like this.