• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2005.09a
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• pp.15-18
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• 2005

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.114-120
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• 2005

In this study, a biological reaction and measurement control system was developed to rapidly measure the insecticide imidacloprid residues in agricultural products. The biological reaction part of the system was designed to include micro-pumps and valves for fluid transport, and a polystyrene covet as a reaction chamber. The measurement control part of the system consisted of a photodiode with a light-emitting diode for optical density measurement, and a control microcomputer to implement assay. Signal output was read as the rate of change in optical density at 645 nm. The sensitivity of the system was 2.2 ng/mL ($IC_50$). The system could execute a measurement cycle in about 19 minutes. Research will be continued to develop an automatic sampler fur imidacloprid residues from agricultural products.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.281-286
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• 2005

We created a new graphite-Cu(II) electrode and found that the electrode could catalyze FADH$_2$ oxidation and FAD reduction coupled to electricity production and consumption, respectively. In a fuel cell with graphite-Cu(II) anode and graphite-Fe(III) cathode, the electricity was produced by coupling to the spontaneous oxidation of FADH$_2$ Fumarate and xylose were not produced from the enzymatic oxidation of succinate and xylitol without FAD, respectively, but produced with FAD. The production of fumarate and xylose in the reactor with FAD electrochemically regenerated was maximally 2- 5 times higher than that in the reactor with FAD. By using this new electrode with catalytic function, a bioelectrocatalysts can be engineered; namely, oxidoreductase (e.g., lactate dehydrogenase) and FAD can function for biotransformation without an electron mediator and second oxidoreductase for cofactors recycling.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.362-368
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• 2001

The effects of water soluble materials in paper mill sludge on cellulase and $\beta$-glucosidase activities were studied while the optimization of enzyme system for hydrolysis of the paper mill sludge for production of glucose was made. Water soluble materials in the paper mill sludge showed stimulatory effect on carboxymethyl cellulose (CMC) activity, inhibitory effect on filter paper (FP) activity, and no effect on avicelase and $\beta$-glucosidase activities. CMC and ${\beta}$-glucosidase activities at 5 and 10, 5 or 10 and 10, and 10 and 10 U/ml were optimal for hydrolysis of 5, 10, and 20% of the paper mill sludge, respectively.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.85-87
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• 1994

Feeding biological cells one by one is the key point in the manipulation of cells. The conventional valve systems have many difficulties in feeding cells one by one, because they shut the whole flow of fluids when they are closed and have possibilities of breaking the fragile cells. They need some other equipments for continuous supply of suspension and to protect the cells. We design a check valve for feeding biological cells one by one using polyimide all the silicon substrate. The cells are fed by hydraulic pressure through the isotropically etched cavity. When the suspension flows continuously along the channel the valve is bent by hydraulic pressure and a cell is fed to the outlet. We have studied a cell fusion device fabricated with polyimide and electroplating. If the designed check valve is located in front of the cell fusion device it is helpful to fuse two different kinds of cells.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.83-89
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• 2012

Due to the potential importance and usefulness, usage of highly ordered nanoporous anodized aluminum oxide can be broadened in industry, when highly ordered anodized aluminum oxide can be placed on a substrate with controlled thickness. Here we report a facile route to highly ordered nanoporous alumina with the thickness of hundreds-of-nanometer on a silicon wafer substrate. Hexagonally or tetragonally ordered nanoporous alumina could be prepared by way of thermal imprinting, dry etching, and anodization. Adoption of reusable polymer soft molds enabled the control of the thickness of the highly ordered porous alumina. It also increased reproducibility of imprinting process and reduced the expense for mold production and pattern generation. As nanoporous alumina templates are mechanically and thermally stable, we expect that the simple and costeffective fabrication through our method would be highly applicable in electronics industry.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3143-3146
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• 2013

• Macromolecular Research
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• v.15 no.2
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• pp.154-159
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• 2007

Polyaniline (PANI) nanospheres, 4 run in diameter, were fabricated by the microemulsion polymerization of octyltrimethyl ammonium bromide (OTAB). The size of the PANI nanoparticles could be controlled as functions of the surfactant concentration, surfactant spacer length and polymerization temperature. The diameter of the PANI nanospheres decreased with increasing surfactant concentration and decreasing temperature. The PANI nanoparticles revealed enhanced conductivity compared to conventional bulk PANIs. In addition, the PANI nanoparticles could be applied as optically transparent conducting materials due to their high conductivity and the nanosize effect. With 9 wt% PANI in the PC matrix, the PANI/PC film exhibited a conductivity of $8.9\times10^{-3}S/cm$ and transparency exceeding 95% over the entire visible light range.

• Macromolecular Research
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• v.16 no.5
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• pp.418-423
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• 2008

Poly[(R)-3-hydroxy butyrate] (PHB) and methoxy poly(ethylene glycol) (mPEG) were conjugated by the transesterification reaction with tin(II)-ethylhexanoate (Sn(Oct)-II) as a catalyst. Hydrophobic PHB and hydrophilic mPEG formed an amphiphilic block copolymer which was formed with the self-assembled polymeric micelle in aqueous solution. In this study, we tried to determine the optimum ratio of hydrophobic/hydrophilic segments for controlled drug delivery. The particle size and shape of the polymeric micelle were measured by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Their size were 61-102 nm with various block ratios. Griseofulvin was loaded in the polymeric micelle as a hydrophobic model drug. The loading efficiency and release profile were measured by high performance liquid chromatography (HPLC). The model drug in our system was constantly released for 48 h.

• Macromolecular Research
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• v.16 no.8
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• pp.711-716
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• 2008

We synthesized gold nanonetwork using the amphiphilic polymer brush, poly(oxyethylene) containing decyltri(oxyethylene)thiomethyl ($C_{10}H_{21}(OCH_2CH_2)_3SCH_2-$) side groups, as a stabilizer and/or a template. When tetrabutylammonium borohydride solution in THF was added to a mixture solution of the polymer and $LiAuCl_4$ in THF, 0-D gold nanomaterials were obtained. However, when an aqueous solution of sodium borohydride was added, gold nanonetworks were synthesized. The composites composed of polymer/0-D gold nanomaterials and polymer/gold nanonetworks showed electrical conductivities of ${\sim}10^{-9}$ and ${\sim}10^{-3}S/cm$, respectively, which indicated that the gold nanonetworks increased the electrical conductivity.