• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.11
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• pp.767-774
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• 2008

This paper presented the heat transfer and pressure drop characteristics for micro plate heat exchanger with straight channel. The metal sheets for straight channel are manufactured by chemical etching and fabricated micro plate heat exchangers by using the vacuum brazing of bonding technology. The performance experiments are performed within the Reynolds numbers range of 15$\sim$250 under the same flow rate conditions for hot and cold sides. The inlet temperature of hot and cold water are conducted in the range of $30^{\circ}C{\sim}50^{\circ}C$ and $15^{\circ}C{\sim}25^{\circ}C$, respectively. Heat transfer rate and pressure drop are evaluated by the Reynolds numbers and mass flow rates as the inlet temperature variations of the hot and cold sides. Correlations of Nusselt number and friction factor are suggested for micro plate heat exchanger with straight channel using the results of performance experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.759-760
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• 2007

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.59-64
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• 2008

Micro machining can manufacture complex shapes with high accuracy. Especially, this enables wide application of micro technology in various fields. For example, micro channels allow fluid transfer, which is a widely used technology. Therefore, liquidity research of flow in micro channels and micro channel manufacturing with use of various materials and cutting conditions has very important meaning. In this study, to find out correlation between fluid velocity in micro channels and surface roughness, we manufactured micro channels using micro end-mill and dropped ethanol into micro channels. We compared several surface roughness and fluid velocity in micro channels that were created by various processing conditions. Finally, we found out relationship between fluid velocity and surface roughness in micro channels of different materials.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.717-720
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• 2003

A chromogenic biosensor employing microfluidics on a chip has been developed for the determination of high-density lipoprotein (HDL) cholesterol (HDL-C) in human serum. We have investigated a plain and effective method to immobilize enzymes within the microchip without chemically modifying micro-channel or technically micro-fabricating column reactor and fluid channel network. In assessing risk factors of coronary heart disease, a micro-chip system would minimize requirements of instrument and reagent handling.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.17-24
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• 2003

A mathematical model of the hydrodynamic and heat transfer performances of two-phase flow (gas-liquid) in thin film region of micro channel is proposed. For the formulation of modeling, the flow of the vapor phase and the shear stress at the liquid-vapor interface are considered. In this work, disjoining pressure and capillary force which drive the liquid flow at the liquid-vapor interface in thin film region are adopted also. Using the model, the effects of the variations of channel height and heat flux on the flow and heat transfer characteristics are investigated. Results show that the influence of variation of vapor pressure on the liquid film flow is not negligible. The heat flux in thin-film region is the most important operation factor of micro cooler system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.5 s.236
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• pp.707-715
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• 2005

In this work, Scalar Passive code in Lattice Boltzmann Method is employed to simulate two-phase flow of low Reynolds number in a micro-channel. The mixing characteristics in a micro-channel is a function of Peclet number. The mixing length increases with the Peclet number. It is found that with the inclusion of static elements at the channel, rapid mixing of two liquids can be achieved, as shown by the results of computer simulations. The enhancement in mixing performance is thought to be caused by the generation of eddies and by lateral velocity component when the mixture flows past static elements. The results indicate that the size of static element has more effect on the mixing than the number of static element.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.24 no.1
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• pp.103-119
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• 2020

In this work, the hydromagnetic and thermal characteristics of natural convection flow in a vertical parallel plate micro-porous-channel with suction/injection is analytically studied in the presence of Hall current by taking the temperature jump and the velocity slip at the wall into account. The governing equations, exhibiting the physics of the flow formation are displayed and the exact analytical solutions have been obtained for momentum and energy equations under relevant boundary conditions. The impact of distinct admissible parameters such as Hartmann number, Hall current parameter, permeability parameter, suction/injection parameter, fluid wall interaction parameter, Knudsen number and wall-ambient temperature ratio on the flow formation is discussed with the aid of line graphs. In particular, as rarefaction parameter on the micro-porous-channel surfaces increases, the fluid velocity increases and the volume flow rate decreases for injection/suction.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.228-233
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• 2005

Two-dimensional Stokes flows through a micro channel with a couple of symmetric vertical fins are investigated. At far up- and down-stream from the fins, the plane Poiseuille flow exists in the channel. The slip boundary conditions are applied to take account of the Knudsen number effects. For the analysis, the method of eigen function expansion and collocation method are employed. By the results, the streamline patterns and pressure distributions are shown and the force exerted on the fin and the excess pressure drop due to the fins are determined as functions of the length of the fin and Knudsen number. It may be conjectured that the force and the excess pressure drop are almost independent of the Knudsen number.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.3
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• pp.256-264
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• 2012

A general procedure for the optimal design of a micro-channel heat exchanger for heat pump systems is presented. For this design, a performance analysis program that can reflect the various geometric variables of the micro-channel heat exchanger was developed. The deviation between simulated and experiment results of previous research was within 4% for the heat transfer rate. To prove the feasibility of the optimal design process, the performance of the reference heat exchanger was compared to that of the optimized heat exchanger. The $JF_{air}$ and PECv of the optimized heat exchanger were enhanced by 14% and 26%, respectively.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.280-284
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• 2023

In this study, a prototype micro-scale photomask and microfluidic channel mold were fabricated using the thermal shrinkage of the polymer. A polystyrene (PS) sheet was used as the heat-shrink polymer, and the patterns of the photomask and microchannel are interdigitated electrodes. Patterns were formed on the PS sheets using a commercial laser printer. The contraction ratio of the PS sheet was approximately 60% at a temperature of 150 ℃, and the transmittance was reduced by approximately 0% at a wavelength of 365 nm. The microfluidic channel had a round shape. The proposed technique is simple, facile, and inexpensive for fabricating a micro-scale photomask and microfluidic channel mold and does not involve the use of any harmful materials. Thus, this technique is well-suited for fabricating diverse micro-scale patterns and channels for prototype devices, including sensors.