• 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.

• Journal of the Korea Convergence Society
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• v.9 no.10
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• pp.237-242
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• 2018

A micromixer is a component of a lab-on-a-chip or microfluidic device that mixes two or more chemicals together(convergence). The purpose of this study is to assess the performance of passive micromixer of various shapes. Six shapes of micromixers were compared and three dimensional modeling was carried out to have the same hydraulic diameter. The commercial code, ANSYS Fluent, was used to simulate the internal mixing flow. A numerical analysis method is described in detail in this paper. The performance of the micromixer was compared with the mixing index and pressure drop. Consequently, the CDM-8T shape showed reasonable mixing performance and relatively low pressure drop.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.52.1-52.1
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• 2005

• 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.9
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• pp.851-857
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• 2010

In this study, an experiment was performed to obtain the optimum design of a passive micromixer for effective mixing by using a microsized device and rectangular obstacles; a low Reynolds number was maintained in the microchannel. The experiment was carried out by varying the number, size, and location of the rectangular obstacles. Further, the Y-channel's shape was optimized for maximizing the mixture ratio, which has limit qualification that an allowed value of pressure drop. The increase in the efficiency of mixing was observed to be greater than that in the case of circular obstacles by approximately 2.5%.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.6 s.348
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• pp.46-52
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• 2006

We report on a high performance 94 GHz MMIC resistive mixer using 70-nm metamorphic high electron mobility transistor (MHEMT) and micro-machined W-band ring coupler. A novel 3-dimensional structure of resistive mixer was proposed in this work, and the ring coupler with the surface micro-machined dielectric-supported air-gap microstrip line (DAMLs) structure was used for high LO-RF isolation. The fabricated mixer showed an excellent LO-RF isolation of -29.3 dB and a low conversion loss of 8.9 dB at 94 GHz. To our knowledge, compared to previously reported W-band mixers, the proposed MHEMT-based resistive mixer using micro-machined ring coupler has shown superior LO-RF isolation as well as similar conversion loss.

• The KSFM Journal of Fluid Machinery
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• v.8 no.5 s.32
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• pp.47-53
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• 2005

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.1
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• pp.33-37
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• 2005

A micromixer plays an important role in Bio-MEMS or μ-TAS. Mixing is generally generated by turbulence and interdiffusion of two fluids. Because of low Reynolds number values (Re << 2000) within microchannels, it is difficult to generate turbulence, and consequently mixing mainly depends on interdiffusion. So, channel distance is often prohibitively long to mix two different fluids properly. To reduce this mixing length, we proposed a new mixer for micromixing in which two fluids were effectively mixed by an ultrasonic wave generated by PMN-PT. The ultrasonic wave was radiated into a chamber In the cross-sectional direction into the boundary surface formed by two fluids. The two fluids were positioned one on top of the other. The mixing state was measured by observing the color of samples due to the reaction of NaOH and phenolphthalein.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.38-38
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• 2003

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.93-96
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• 2009

In the cathode channel of a PEM fuel cell, the local concentration of oxygen near the gas diffusion layer (GDL) decreases in streamwise direction due to chemical reactions, which degrades the efficiency of the oxygen consumption and overall fuel cell efficiency. We numerically studied the influence of the swirling flow generated by a slanted groove mixer (SGM) on the concentration distribution of oxygen. We found that the swirling flow can increase the concentration of oxygen near the GDL, and subsequently improves the oxygen consumption rate.