• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.128-135
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• 2007

Micro-channels for a wave micropump have been fabricated using the Stereolithography and UV Photolithography. The micro-channel with a channel height of $500\;{\mu}m$ was fabricated with stereolithography. UV photolithography was used for producing micro-channels with a channel length less than $100\;{\mu}m$. The fabrication process data including spinning rpm, pre-bake and post-bake time, and develop time for single layer and multiple layer 3D micro-structures using SU-8 photo resist are experimentally found. A film mask printed with a 40,000 dpi laser printer was used for UV lithography and micro-structures in the order of tens of micrometers in dimension were successfully fabricated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.2 s.245
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• pp.157-163
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• 2006

Our research dealt with micro fabrication using micro forming process. The goal of the research was to establish the limit of forming process concerning the size of forming material and formed shape. Flat-rolled ultra thin metallic foils of pure copper(3.0 and $1.0{\mu}m$ in thickness)and stainless steel($2.5{\mu}m$ in thickness) were used for forming material. We obtained the various shapes of micro channels as using designed forming process. $12-14{\mu}m$ wide and $9{\mu}m$ deep channels were made on $3.0{\mu}m$ thick foil and $6{\mu}m$ wide and $3{\mu}m$deep channels were made on $1.0{\mu}m$ thick foil. Si wafer die for forming was fabricated by using etching technique. And the relation of etching time and die dimension was investigated for fabricating precisely die groove. For the forming, die and metal foil were vacuum packed and the forming was conducted with a cold isostatic press. The formed channels were examined in terms of their dimension, surface qualities and potential for defects. Base on the examinations, formability of ultra thin metallic foil was also discussed. Finally, we compared the forming result with simulation. The result of research showed that metal forming technology is promising to produce micro parts.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.9
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• pp.605-613
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• 2017

Recently, efficient heat dissipation has become necessary because of the miniaturization of devices, and research on boiling on micro-channels has attracted attention. However, in the case of micro-channels, the friction coefficient and heat transfer characteristics are different from those in macro-channels. This leads to large errors in the micro scale results, when compared to correlations derived from the macro scale. In addition, due to the complexity of the mechanism, the boiling phenomenon in micro-channels cannot be approached only by experimental and theoretical methods. Therefore, numerical methods should be utilized as well, to supplement these methods. However, most numerical studies have been conducted on macro-channels. In this study, we applied the lattice Boltzmann method, proposed as an alternative numerical tool to simulate the boiling phenomenon in the micro-channel, and predicted the bubble growth process in the channel.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.5
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• pp.1090-1095
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• 2014

The experimental and numerical studies of the single-phase flow pressure drop in parallel micro-channels were performed. The parallel micro-channels consisted of 15 channels with depth 0.2mm, width 0.45mm and length 60mm. The FC-72 was used as the working fluid and the mass fluxes ranged from 62.8 to $1371.6kg/m^2s$. The numerical analysis was performed iterative calculations to solve governing equations and finds the appropriate value. The experimental data was compared with the numerical data, the results showed good agreement with the numerical data.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.3
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• pp.879-894
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• 2016

In micro-fluid systems, fluids are injected into extremely narrow polymer channels in small amounts such as micro-, nano-, or pico-liter scales. These channels themselves are embedded on tiny chips. Various specialized structures in the chips including pumps, valves, and channels allow the chips to accept different types of fluids to be entered the channel and along with flowing through the channels, exert their effects in the framework of different reactions. The chips are generally crystal, silicon, or elastomer in texture. These highly organized structures are equipped with discharging channels through which products as well as wastes of the reactions are secreted out. A particular advantage regarding the use of fluids in micro-scales over macro-scales lies in the fact that these fluids are much better processed in the chips when they applied as micro-scales. When the laboratory is miniaturized as a microchip and solutions are injected on a micro-scale, this combination makes a specialized construction referred to as "lab-on-chip". Taken together, micro-fluids are among the novel technologies which further than declining the costs; enhancing the test repeatability, sensitivity, accuracy, and speed; are emerged as widespread technology in laboratory diagnosis. They can be utilized for monitoring a wide spectrum of biological disorders including different types of cancers. When these microchips are used for cancer monitoring, circulatory tumor cells play a fundamental role.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1821-1824
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• 2008

A novel in-mold packaging process has been developed to manufacture devices with closed channels. In this unified process, fabrication of open channels and forming the rigid cover on top of them are sequentially integrated in the same mold. The entire process is comprised of two phases. In the first phase, the open channels are fabricated under an exquisitely controlled temperature and pressure using the conventional micro injection molding technology. In the second phase, the closed channels are fabricated by conducting the injection molding process using the molded structure with the open channels as a mold insert. As a result, the in-mold technology can eliminate the bonding processes such as heating, ultrasonic or chemical processes for cohesion between the channel and the cover, which have been required in conventional methods.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.49-50
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• 2002

In micro-channels, the electro-viscous effect is caused by the electrical double layer on pressure-driven liquid flow. Velocity fields of flow inside micro-channels were measured using micro-PIV system for investigating the electro-viscous effect. De-ionized water and aqueous NaCl solutions with four different concentrations were used as working fluid in a PDMS micro-channel of $100{\mu}m$ width and $66{\mu}m$ height. The pressure gradient, dP/dx, was determined from the pre-determined input flow rate Q of syringe pump. The mean velocity $u_m$ used for calculating Reynolds number was obtained from the PIV velocity field data. These are used to plot the pressure gradient as a function of Reynolds numbers. The pressure gradient far lower concentration solution $(10^{-5}\;M)$ was higher than that for the higher concentration solution. The increase of flow resistance was about $30\%\;and\;37.5\%$ at Re=0.02 and 0.06, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.551-552
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• 2006

The miniature fuel cells have emerged as a promising power source for applications such as cellular phones, small digital devices, and autonomous sensors to embedded monitors or to micro-electro mechanical system (MEMS) devices. Several chemicals run candidate at a fuel in those systems, such as hydrogen. methanol, ethanol, acetic acid, and di-methyl ether (DME). Among them, hydrogen shows most efficient fuel performance. However, there are some difficulties in practical application for portable power sources. Therefore, more recently, there have been many efforts for development of micro-reformer to operate highly efficient micro fuel cells with liquid fuels such as methanol, ethanol, and DME In our experiments, we have integrated a micro-fuel processor system using low temperature co-fired ceramics (LTCC) materials. Our integrated micro-fuel processor system is containing embedded heaters, cavities, and 3D structures of micro- channels within LTCC layers for embedding catalysts (cf. Figs. 1 and 2). In the micro-channels of LTCC, we have loaded $CuO/ZnO/Al_2O_3$ catalysts using several different coating methods such as powder packing or spraying, dipping, and washing of catalyst slurry.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.539-540
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• 2006

It is so difficult to small amounts of two or more fluid species into single in microchannel because flows are usually laminar. In this regard multilamination micro mixer including recirculation zone is presented. Alternating feed micro channels make multilamination and converging-diverging channels form recirculation zone. Multilamination with geometric focusing decreases diffusion path ana recirculation zones make vortex. In this paper flow patterns and mixing properties of multilamination micro mixer including recirculation zone were investigated by Computational Fluid Dynamics (CFD). The CFD results provided qualitative information on mixing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.49-53
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• 2005

The objective of this research was to establish the size limitation of micro metal forming and analyze the formability of foil. Flat-rolled ultra thin metallic copper foil($3{\mu}m$ in thickness) was used as a forming material and foil was annealed to improve the formability at the temperature of $385^{\circ}C$. Forming die was fabricated by using etching technique of DRIE(deep reactive ion etching) and HNA isotropic etching. For the forming die and coupe. foil were vacuum packed and the forming was conducted as applying hydrostatic pressure of 250MPa to the vacuum packed unit. We successfully obtained the micro channels of $12\~14{\mu}m$ width and $9{\mu}m$ depth from micro forming process we designed. We also investigated the thickness strain distribution of foil from experiment and FE simulation result. Micro channels had a good formability of smooth surface and size accuracy. We expect that micro metal forming technology will be applied to production of micro parts.