• Journal of Biomedical Engineering Research
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• v.28 no.2
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• pp.244-249
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• 2007

Fluidic conditions for the separation of phases were surveyed in a microfluidic aqueous two-phase extraction system. The infusion ratio between polyethylene glycol (PEG) and dextran solution defines the concentrations of each polymer in micro-channel, which determine the phase-separation. The appropriate ratio between PEG (M.W. 8000, 10%, w/v) and dextran T500 (M.W. 500000, 5%, w/v) in order to perform the separation of phases of both polymers was observed as changing the mixed ratio of both polymers. Based on the fluidic conditions, stable two-phase solutions were obtained within 4% to 8% and 3% to 1% of PEG and dextran, respectively. In addition, the characteristics of the two-phase were discussed. The separation technique studied in the paper can be applied for the implementation of a lab-on-a chip which can detect various biological entities such cells, bacterium, and virus in an integrated manner using built in a biosensor inside the chip.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.5
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• pp.432-443
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• 2005

Microarray technology has contributed Significantly to the understanding of bacterial genetics and transcriptional regulation. One neglected aspect of this technology has been optimization of microarray-generated signals and quality of generated information. Full genome microarrays were developed for Clostridium acetobutylicum through spotting of PCR products that were designed with minimal homology with all other genes within the genome. Using statistical analyses it is demonstrated that Signal quality is significantly improved by increasing the hybridization volume. possibly increasing the effective number of transcripts available to bind to a given spot, while changes in labeled probe amounts were found to be less sensitive to improving signal quality. In addition to Q-RT-PCR, array validation was tested by examining the transcriptional program of a mutant (M5) strain lacking the pSOL1 178-gene megaplasmid relative to the wildtype (WT) strain. Under optimal conditions, it is demonstrated that the fraction of false positive genes is 1% when considering differentially expressed genes and 7% when considering all genes with signal above background. To enhance genomic-scale understanding of organismal physiology, using data from these microarrays we estimated that $40{\sim}55%$ of the C. acetobutylicum genome is expressed at any time during batch culture, similar to estimates made for Bacillus subtilis.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.540-546
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• 2004

We deviced a new graphite-Mn(II) electrode and found that the modified electrode with Mn(II) can catalyze NADH oxidation and $NAD^+$ reduction coupled to electricity production and consumption as oxidizing agent and reducing power, respectively. In fuel cell with graphite-Mn(II) anode and graphite-Fe(III) cathode, the electricity of 1.5 coulomb (A x s) was produced from NADH which was electrochemically reduced by the graphite-Mn(II) electrode. When the initial concentrations of pyruvate and acetaldehyde were adjusted to 40 mM and 200 mM, respectively, about 25 mM lactate and 35 mM ethanol were produced from 40 mM pyruvate and 200 mM acetaldehyde, respectively, by catalysis of ADH and LDH in the electrochemical reactor with $NAD^+$ as cofactor and electricity as reducing power. By using this new electrode with catalytic function, the bioelectrocatalysts are engineered; namely, oxidoreductase (e.g., lactate dehydrogenase) and $NAD^+$ can function for biotransformation without electron mediator and second oxidoreductase for $NAD^+$/NADH recycling.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.1120-1124
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• 2006

Supplementation with rice oil and its major components (oleic acid and linoleic acid) was found to have a significant influence on cephalosporin C (CPC) production and cell growth by A. chrysogenum M35 in shake flask cultures. Five percent (v/v) rice oil had the most robust effect and 5% (v/v) oleic acid was the second most efficient on cell growth, whereas 3% (v/v) linoleic acid was found to be optimal for CPC production. Rice oil, oleic acid, and linoleic acid also significantly improved the rates of glucose consumption. When glucose was almost consumed, CPC production was initiated and, on the addition of rice oil, lipase activity increased steadily to 1.56 U/ml for 4 days. These results suggest that rice oil and fatty acids are used as carbon source to produce CPC by A. chrysogenum M35. Moreover, a mixture, composed of 40% (v/v) oleic acid and 60% (v/v) linoleic acid, had the strongest stimulatory effect on CPC production, due to a synergistic effect of the two fatty acids. Consequently, the maximum CPC titer (7.44 g/l) was improved about 4.5-fold.

• Environmental Engineering Research
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• v.10 no.5
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• pp.239-246
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• 2005

The effect of Pt addition over $V_2O_5-WO_3/TiO_2$ catalyst supported on PRO-66 was investigated for NO reduction in order to develop the catalytic filter working at low temperature. Catalytic filters, $Pt-V_2O_5-WO_3/TiO_2/PRD$, were prepared by co-impregnation of Pt, V, and W precursors on $TiO_2$-coated ceramic filter named PRD (PRD-66). Titania was coated onto the pore surface of the ceramic filter using a vacuum aided-dip coating method. The Pt-loaded catalytic filter shifted the optimum working temperature from $260-320^{\circ}C$(for the catalytic filter without Pt addition) to $190-240^{\circ}C$, reducing 700 ppm NO to achieve the $N_x$ slip concentration($N_x\;=\;NO+N_2O+NO_2+NH_3$) less than 20 ppm at the face velocity of 2 cm/s. $Pt-V_2O_5-WO_3/TiO_2$ supported on PRD showed the similar catalytic activity for NO reduction with that supported on SiC filter as reported in a previous study, which implies the ceramic filter itself has no considerable interaction for the catalytic activity.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.313-315
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• 1997

We developed a new analysis technique for the assessment of irregular vibratory movement of vocal folds. Successive frames of pre-recorded video images from videostroboscopy were transferred to computer memory and a vibratory tract of one selected point was described as a waveform by displaying the same lines of all frames along the y-direction. By applying this technique, irregular vibratory patterns of multiple regions, such as asynchronized registration of glottal cycles, could be easily visualized. It would be possible to monitor and analyze the pathologic changes of vocal fold movement by means of this newly developed system.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.5
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• pp.331-338
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• 2004

The Separation of two amino acids, phenylalanine and tryptophan, was carried out using laboratory simulated moving bed (SMB) chromatography. The SMB process consisted of four zones, with each zone having 2 columns. The triangle theory was used to obtain the operating conditions for the SMB. The mass transfer coefficients of the two amino acids were obtained from the best-fit values by comparing simulated and experimental pulse data. The competitive adsorption isotherms of the two amino acids were obtained by single and binary frontal analyses, taking into consideration the competition between the two components. A competitive Langmuir isotherm, obtained from single-component frontal chromatography, was used in the first run, and the isotherm from binary frontal chromatography in the second, with the flow rate of zone 1 modified to improve the purity. Compared to the first and second runs, the competitive Langmuir isotherm from the binary frontal chromatography Showed good agreement with the experimental results. Also, adjusting the flow rate in zone 1 increased the purity of the products. The purities of the phenylalanine in the raffinate and the tryptophan in the extract were 99.84 and $99.99\%$, respectively.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.598-603
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• 2008

In petrochemical complex, Hydrogen Network optimization is surveying the extra Hydrogen and needed Hydrogen of each company and calculating the optimized distribution. This paper compares the case of using the existing pipeline and the case of not using the existing pipeline to show the effect quantitatively and clearly by modeling the both cases and using mathematical programming. As a result, using the existing pipeline can save the pipe cost over 20% and increase the whole network benefit by thirteen billion won.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.111-115
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• 2015

To produce patterns with high resolution in gravure printing, it is important to increase ink transfer ratio. The ink which has higher affinity with substrate can be transferred more from the roll to the substrate due to the good wettability between ink and substrate. However, it is difficult to evaluate the affinity between the substrate and the ink which is viscoelastic in nature. In this study, we suggest a practical method to evaluate the interfacial interaction between the ink and various substrates.

• KSBB Journal
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• v.14 no.6
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• pp.737-741
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• 1999

Phenanthrene degrading bacteria were isolated from the petroleum contaminated soil near an oil tank. Four of 15 strains decreased surface tension of culture broth of phenanthrene-containing minimal media. H6, one of the isolated bacteria decreased surface tension of culture broth below 33 dyne/cm during growth on glucose. H6 was identified as Bacillus subtilis and biosurfactant produced by H6 was lipopeptide. The biosurfactant was produced at 0.13 g/L in the mineral medium containing 2% glucose. Critical micelle concentration(CMC) of the biosurfactant was 52 mg/L. Foaming power was similar to Tween 80 and dispersing power was superior to Tween 80m SDS and Brij30. High thermal stability and emulsion index were also observed.