• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.1-8
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• 2013

The water-in-fuel droplets were applied to investigate the effect of mixing ratio between water and decane, ambient temperature, droplet size and spacing between droplets on ignition and micro-explosion in a heated chamber with high temperature. The ignition temperature of droplet was found lower as the droplet size was increased and the contents of water was decreased. The life time of droplet, however, decreases as the contents of water increases due to the micro-explosion. The occurrence of micro-explosion also increases as the size of droplets and the ambient temperature increase. The flame spread speed gets faster as the contents of water and the number of suspender decreases.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.1-8
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• 2015

Micro igniter on the glass membrane for MEMS thruster was developed. The stability of the micro igniter by using a glass membrane with a thickness of tens of microns was improved. The micro igniter was fabricated by anisotropic wet etching of photosensitive glass and deposition of Pt/Ti for electric heat coil. The solid propellant was loaded into the propellant chamber without an especial technique due to the high structural stability of the glass membrane. Ignition tests were performed successfully. The minimum ignition delay was 27.5 ms with an ignition energy of 19.3 mJ.

• Korean Journal of Materials Research
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• v.20 no.7
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• pp.374-378
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• 2010

$MgTiO_3$ thin films were prepared by r.f. magnetron sputtering in order to prepare miniaturized NPO type MLCCs. $MgTiO_3$ films showed a polycrystalline structure of ilmenite characterized by the appearance of (110) and (202) peaks. The intensity of the peaks decreased with an increase in the chamber pressure due to the decrease of crystallinity which resulted from the decrease of kinetic energy of the sputtered atoms. The films annealed at $600^{\circ}C$ for 60min. showed a fine grained microstructure without micro-cracks. The grain size and roughness of the $MgTiO_3$ films decreased with the increase of chamber pressure. The average surface roughness was 1.425~0.313 nm for $MgTiO_3$ films prepared at 10~70 mTorr. $MgTiO_3$ films showed a dielectric constant of 17~19.7 and a dissipation factor of 2.1~4.9% at 1MHz. The dielectric constant of the films is similar to that of bulk ceramics. The dielectric constant and the dissipation factor decreased with the increase of the chamber pressure due to the decrease of grain size and crystallinity. The leakage current density was $10^{-5}\sim10^{-7}A/cm^2$ at 200kV/cm and this value decreased with the increase of the chamber pressure. The small grain size and smooth surface microstructure of the films deposited at high chamber pressure resulted in a low leakage current density. $MgTiO_3$ films showed a near zero temperature coefficient and satisfied the specifications for NPO type materials. The dielectric properties of the $MgTiO_3$ thin films prepared by sputtering suggest the feasibility of their application for MLCCs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.73-79
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• 1968

The resolving capacities of xanthophyll pigments on thin-layers of Silica Gel, Hyflo super-Cel, and Micro-Cel C with varying concentrations of acetone in petroleum ether as the developing solvent were compared. The results showed that the resolving capacity of Micro-Cel C thin-layer was superior to others and satisfactory for the separation of leaf carotenoids in clearly separated six bands; carotenes, lutein-zeaxanthin, antheraxanthin, violaxanthin, an unidentified band, and neoxanthin, when it was developed with $13\%$ acetone-petroleum ether solution for 15 to 20minutes in an unsaturated chamber. Adhension of Micro-Cel C to glass was adequate without binder. Calcium sulfate used as a binder appeared to inactivate the resolving capacity of Micro-Cel C. Removing an about 0.2cm-wide layer on bo side of thin-layer slide helped to prevent 'edge effect' which gave tailing and faster solvent ascending along the side than the center. An adequate thickness of thin-layer was obtained when a 3 ml aliquot of the suspension in which l0g powdered Micro-Cel C was suspended in 75 ml distilled water was coated on a $2\times20cm$ glass slide.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.1-7
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• 2017

The performance of a MEMS solid propellant thruster was predicted and analyzed through internal ballistics model and CFD analysis. The nozzle throat was $416{\mu}m$, and the area ratio of the nozzle was 1.85. As a result of the internal ballistics model, chamber pressure increased up to 197 bar and the maximum thrust was 3,836 mN. In CFD analysis, the chamber pressure of the internal ballistics model was applied as the operating pressure, and the CFD model was divided into an adiabatic and a heat loss model. As a result, the maximum thrust of the adiabatic model was 14.92% lower than that of the internal ballistics model, and the effect of heat loss was insignificant.

• Journal of Embryo Transfer
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• v.18 no.3
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• pp.171-178
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• 2003

This study was conducted to investigate the effect of electric fusion methods on cell fusion rate and embryo development by somatic cell nuclear transfer in Korean Native Cattle. The KNC ear cell was cultured in vitro for confluence in serum starvation condition(DMEM＋0.05％ FBS) for cell confluence. The zona pellucida of IVM oocytes were partially dissection using micro pipette. Ear cells were transferred into an enucleated oocyte. The reconstructed embryos were electrically fused with Zimmermann Cell Fusion Medium(ZCFM). Nuclear transfer embryos were activated with a combination of 10${\mu}{\textrm}{m}$ calcium ionophore(5 min) and 2.0mM 6-DMAP(3 hr). The activated embryos were cultured in CR1 -aa medium contains 0.3％ BSA or 10％ FBS at 37$^{\circ}C$, 90％ $N_2$, and 5％ $CO_2$in incubator for 6 days. The fusion rates were 51.6％(chamber) and 68.9％(needle), respectively and there were significantly difference between the fusion method(P<0.05). But, lysis rates were not significantly different(10.7％, 11.5％), respectively. The cleavage rates were significantly different between the chamber method(73.2％) and needle method(80.3％), respectively(P<0.05). The rates of early embryos(2∼4cells) and blastocysts of chamber and needle methods were 54.1％, 61.1％ and 18.4％, 26.3％ respectively, and needle method was significantly higher than chamber method(P<0.05). But, morulae formation rate were not significantly differences between the chamber(6.7％) and needle(6.2) method(P <0.05). These result suggest that electric fusion of needle method was to be profitable for nuclear transfer embryo fusion rate, blastocyst formation rate and reduce of oocyte lysis.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1900-1905
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• 2007

A micro cyclone combustor was developed to be used as a heat source of thermoelectric power generator (TPG). The cyclone combustor was designed so that fuel and air were supplied to the combustion chamber separately. The mixing and flow characteristics in the combustor were investigated numerically. The global equivalence ratio (${\Phi}$), defined using the fuel and air flow rates, was introduced to examine the flow features of the combustor. The mixing of fuel and air inside the combustor could be well understood using the fuel concentration distribution. It was found that the weak recirculating zone was formed upper the fuel-supplying tube in case of ${\Phi}$ < 1.0. In addition, it was found that small regions that have a negative axial velocity exist near the fuel injection ports. It is assumed that these negative axial velocity regions can stabilize a flame inside the micro cyclone combustor.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.139-144
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• 2007

A micro cyclone combustor was developed to be used as a component of mobile power generator (MPG). The cyclone combustor was designed so that fuel and air were supplied to the combustion chamber separately to prevent a flash-back. The flame shape stabilized inside the micro cyclone combustor was visualized experimentally and the flow field and the combustion characteristics of the combustor were investigated numerically. The global equivalence ratio (${\Phi}$), defined using the fuel and air flow rates, was introduced to examine the overall flow and flame features of the combustor. The flame stabilization mechanism could be well understood using the velocity distribution inside the combustor. For only non-reacting case, it was found that a weak recirculating zone was formed upper the fuel-supplying tube in case of ${\Phi}$ < 1.0. It was also found that small regions that have a negative axial velocity exist near the fuel injection ports for both of non-reacting and reacting case. It was identify that a flame front was stabilized at the negative axial velocity regions near the fuel injection ports.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1466-1467
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• 2008

We describe here a novel micro total analysis system for the purification and identification of the affinity-captured proteins. Also we demonstrated the mass analysis of the Carcinoembrionic antigen (CEA) and Alpha femtoprotein which were chosen as the target cancer marker. For MALDI-TOF analyses, the proteins should to be separated from a protein mixture and be concentrated when needed. This procedure usually takes a long time even before protease-digested samples are to be obtained from them. Here, we describe integrated and efficient micro chip for protein purification and digestion for MALDI-TOF analyses. At first, disease protein is purified by passing the micro chamber from a protein mixture or human whole serum and released from the micro affinity beads by thermal heating. Purified protein is then transfer to the hole for trypsin digestion. The final sample is analyzed by MALDI-TOF. All the processes could be finished successfully within one hour, which renders MALDI-TOF analyses of a target protein quite simple.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.12
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• pp.1042-1047
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• 2007

A micro cyclone combustor was developed to be used as a heat source of thermoelectric power generator (TPG). The cyclone combustor was designed so that fuel and air were supplied to the combustion chamber separately. The mixing and flow characteristics in the combustor were investigated numerically. The global equivalence ratio ($\Phi$), defined using the fuel and air flow rates, was introduced to examine the flow features of the combustor. The mixing of fuel and air inside the combustor could be well understood using the fuel concentration distribution. It was found that the weak recirculating zone was formed upper the fuel-supplying tube in case of ${\Phi}$<1.0. In addition, it was found that small regions that have a negative axial velocity exist near the fuel injection ports. It is assumed that these negative axial velocity regions can stabilize a flame inside the micro cyclone combustor.