• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1690-1691
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• 2008

Micro cell stimulation device is interested in many researchers because it has several advantages such as saving time and reagents. We introduce new micro-bioreactor using micro bead and conduct cell stimulation experiments to verify effective time because cell have operated by cell-cycle (G1, S, G2, and M phase). Micro-bioreactor was made by soft lithography and CAPE (calf pulmonary artery endothelial cell) was cultured in PDMS (polydimethylsiloxane) micro device for 12 hour and cell starvation process was performed for 24 hours. Micro glass beads were rolled only by slating device every hour during 15 hour because of minimizing other stimulation force like flow and pressure. The result represents that cells under exposed under micro bead stimulation show higher growth rate than normal condition and earlier and later stimulation time are more effective.

• Journal of Power System Engineering
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• v.20 no.2
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• pp.43-50
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• 2016

This research proposal is based on a novel non-contact technique of micro-sized bead injection process for fabrication of electronic paper display. This non-contact injection process is based on the principle of electrostatic force and uses micro-sized metal-coated beads dispersed in a solution. The dispersion retention times of three different solutions with viscosities of 10 cps, 100 cps, and 1000 cps were measured by optical equipment showing the retention times of 5 mins, 10 mins, and 30 mins respectively. The dispersion retention rate dropped as the time passed. The dispersion retention characteristic of 1000 cps solution was more stable as compared to those of 10 cps and 100 cps meaning that higher viscosity has better retention properties. The experimental results of bead injection at different viscosity levels of the solution were also measured and a stable injection result was achieved by using 1000 cps solution. This results show that stable injection is dependent on solution viscosity and dispersion.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1629-1630
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• 2006

This paper describes a micro total analysis system ($\mu$ TAS) for detecting and digesting the target protein which includes a bead based temperature controllable microchip and computer based controllers for temperature and valve actuation. We firstly combined the temperature control function with a bead based microchip and realized the on-chip sequential reactions using two kinds of beads. The PEG-grafted bead, on which RNA aptamer was immobilized, was used for capturing and releasing the target protein. The target protein can be chosen by the type of RNA aptamer. In this paper, we used the RNA aptamer of HCV replicase. The trypsin coated bead was used for digesting the released protein prior to the matrix assisted laser desorption ionization time of flight mass spectrometer (MALDI TOF MS). Heat is applied for release of the captured protein binding on the bead, thermal denaturation and trypsin digestion. PDMS microchannel and PDMS micro pneumatic valves were also combined for the small volume liquid handling. The entire procedures for the detection and the digestion of the target protein were successfully carried out on a microchip without any other chemical treatment or off-chip handling using $20\;{\mu}l$ protein mixture within 20 min. We could acquire six matched peaks (7% sequence coverage) of HCV replicase.

• KSBB Journal
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• v.24 no.5
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• pp.432-438
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• 2009

Here, we demonstrated simple nucleic acid, RNA, concentration method using polymer micro chip containing glass bead ($100\;{\mu}m$). Polymer micro chip was fabricated by PDMS ($1.5\;cm\;{\times}\;1.5\;cm$, $100\;{\mu}m$ in the height) including pillar structure ($160\;{\mu}m\;(I)\;{\times}\;80\;{\mu}m\;(w)\;{\times}\;100\;{\mu}m\;(h)$, gap size $50\;{\mu}m$) for blocking micro bead. RNA could be adsorbed on micro glass bead at low pH by hydrogen bonding whereas RNA was released at high pH by electrostatic force between silica surface and RNA. Amount of glass beads and flow rate were optimized in aspects of adsorption and desorption of RNA. Adsorption and desorption rate was measured with real time PCR. This concentrated RNA was applied to amplification micro chip in which NASBA (Nucleic Acid Sequence Based Amplification) was performed. As a result, E.coli O157 : H7 in the concentration of 10 c.f.u./10 mL was successfully detected by these serial processes (concentration and amplification) with polymer micro chips. It implies this simple concentration method using polymer micro chip can be directly applied to ultra sensitive method to measure viable bacteria and virus in clinical samples as well as environmental samples.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.69-71
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• 2001

본 논문에서는 FACS(fluorescence activated cell sorting)의 초소형화를 위한 미세 유체소자들을 플라스틱 기판에 집적하여 제작하고 전기삼투를 이용해서 세포가 일렬로 이송되는 특성을 시험한다. 제작된 미세 유체 소자는 유리 하부 기판과 플라스틱 상부 기판 및 전원장치로 구성된다. 상부기판은 세포를 주입하기 위한 샘플 측 레저버와 세포를 운반 및 일렬 이송이 가능하게 하는 버퍼를 저장할 두 개의 레저버가 있고 이들이 배출되는 레저버로 구성된다. 마이크로머시닝 기술을 이용하여 실리콘 기판 위에 미세 채널 몰드를 제작한 후 PDMS(polydimethylsiloxane)로 주물을 제작한다. $O_2$ 플라즈마를 이용하여 유리 기판과 PDMS 주물을 접합하며 제작된 채널에 적색 잉크와 bead를 샘플 측에 충전하고 버퍼 측에 sodium borate를 충전한 후 전기삼투로 구동시킨다. bead가 일렬로 이송되도록 전장을 조절하고 이때의 유속과 유량을 측정한다. 다양한 전장에 따른 실험을 통하여 채널의 구조를 최적화한다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.167-168
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• 2006

This paper is concerned about the development system that the bead width's size can be controlled. In order to control the bead width, DC motor driving slide on auto carriage is used. The adjustment of bead width is carried by amplitude and weaving shape is controlled by MCU(Micro Controller Unit). We confirmed the result by tracking experiments.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.30-36
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• 2014

Many different cells types have been found to be highly sensitive to mechanical force imposed by their surroundings. The cellular response to external mechanical forces has very important effects on numerous biological phenomena. In spite of its importance in biological processes, the cell adhesion force remains difficult to measure quantitatively at the cellular level. In this paper, to enhance quantitative measurements of cell adhesive interactions, a new attaching system and a method in which a glass bead can be attached to an AFM cantilever was designed and fabricated, and the degree of range displacement was controlled in the system. In an experiment, the movement of the stage in the attaching system and the attaching process were measured. The effectiveness of this system was confirmed as well in the experiment. In addition, through a commercial AFM system, the spring constant of the modified AFM probe could be measured.

• Journal of Welding and Joining
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• v.28 no.5
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• pp.51-57
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• 2010

Brittle microstructure created in a heat affected zone (HAZ) during the welding of low alloy steel can be eliminated by post-weld heat treatment (PWHT). If the PWHT is not possible during a repair welding, the controlled bead depositions of multi-pass welding should be applied to obtain tempering effect on the HAZ without PWHT. In order to anticipate and control the tempering effect during the temper bead welding, the definition of temperature curve obtained from the analytical solution was suggested in this research. Because the analytical solution for heat flow is expressed as a mathematical equation of weld parameters, it may be effective in anticipating the effect of each weld parameter on the tempering in HAZ during the successive bead depositions. The reheating effect by the successive bead layer on the brittle coarse grained HAZ formed by earlier bead deposition was estimated by comparing the overlapped distance between the temperature curves in the HAZ. Three layered weld specimens of SA508 base metal with A52 filler were prepared by controlling heat input ratio between layers. The tempering effect anticipated by using the overlapped distance between the temperature curves was verified by measuring the micro-hardness distribution in the HAZ of prepared specimens. The temperature curve obtained from analytical solution was expected as a good tool to find optimal temper bead welding conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1025-1028
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• 2004

In this paper, we studied low cycle fatigue behavior of laser welded sheet metal that used automobile body panel. Specimens were manufactured as weld condition and sheet metal using automobile manufacturing company at present. For to know mechanical properties, micro Vicker's hardness test was performed of specimens. But, we can't confirm mechanical properties of weld bead and heat affected zone because laser weld makes very narrow weld bead and heat affected zone than other welding method. Therefore, we performed low cycle fatigue test with similar weldment, dissimilar weldment, similar thickness and dissimilar weldment, and dissimilar thickness and dissimilar weldment for fatigue properties of thickness and welding direction. As well, we analysis stress distribution of base metal, weld bead, and heat affected zone according to strain load using finite element method.

• Laser Solutions
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• v.15 no.3
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• pp.11-15
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• 2012

The laser weld of AZ31 magnesium alloy was characterized with OM, EBSD and micros vickers hardness tester in experiment. EBSD analysis and micro-hardness measurements were carried out at the three regions (Equiaxed Zone, Columnar Dendrite Zone, Base Metal) of the welded AZ31Mg alloy sheets. The magnesium alloy show the rectangular shape bead in laser weld. EBSD analysis revealed that the three regions show the heterogeneous distribution of grain size and microtexture. Micro-hardness measurement also revealed that the heterogeneous distribution of microstructure contributed to the heterogeneous micro-hardness distribution in the three regions.