• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1316-1323
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• 2007

In order to induce high levels of protein secretion, we have constructed a recombinant plasmid, designated pBP244, into which was incorporated key components of the type-II See-dependent secretion system, including LepB (signal peptidase), SecA (ATPase), and SecB (chaperone). The biological activities of the LepB, SecA, and SecB components expressed from genes harbored by pBP244 appeared to play their normal roles. In order to evaluate the protein secretion, a pspA (Streptococcus $\underline{p}neumoniae\;\underline{s}urface\;\underline{p}rotein\;\underline{A}$) gene was cloned into pBP244, resulting in pBP438. S. typhimurium harboring pBP438 grown until the stationary phase, secreted a higher level of PspA into the culture supernatants than did the strain harboring pYA3494. The strain harboring pBP438 secreted a supernatant amount 1.71-fold, a periplasmic space amount 1.47-fold, and an outer membrane amount 1.49-fold higher than that of pYA3494. S. typhimurium ${\chi}8554$ kept the $Asd^+$ plasmid pBP244 and pBP438 for 60 generations in LB broth harboring DAP, thereby indicating that pBP244 and pBP438 were quite stable in the Salmonella strain.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.75.2-75.2
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• 2010

Polymer electrolyte fuel cells (PEFCs) have received a lot of attention as a power source for both stationary and mobile applications due to their attractive feature. In general, the performance of PEFCs is highly affected by the property of the electrodes. A PEFC electrode essentially consists of a gas diffusion layer and a catalyst layer. The gas difusion layer is highly porous and hydrophobicized with PTFE polymer. The catalyst layer usually contains electrocatalyst, proton conducting polymer, even PTFE as additive. Particularly, the proton conducting ionomer helps to increase the catalytic activity at three-phase boundary and catalyst utilization. Futhermore, it helps to retain moisture, resulting in preventing the electrodes from membrane dehydration. The most widely used proton conducting ionomer is perfluorinated sulfonic acid polymer, namely, Nafion from DuPont due to its high proton conductivity and good mechanical property. However, there are great demands for alternative ionomers based on non-fluorinated materials in terms of high temperature availability, environmental adaptability and production cost. In this study, the electrodes with the various content of the sulfonated poly(ether sulfone) ionomer in the catalyst layer were prepared. In addition, we evaluated electrochemical properties of the prepared electrodes containing the various amount of the ionomers by using the cyclic voltammetry and impedance spectroscopy to find an optimal ionomer composition in the catalyst layer.

• Analytical Science and Technology
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• v.12 no.5
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• pp.370-374
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• 1999

Extraction chromatography was used to scarch optimum separation conditions of terbium. Stationary phase was 2-ethylhexyl-2-ethylhexyl phosphonic acid(HEH[EHP])levextrel (-100~+150 mesh), column size was ${\Phi}20{\times}530mm$ and kept constantly temperature at $50^{\circ}C$, adsorption flow rate of $0.2mL/cm^2{\cdot}min$, elution flow rate of $1.0mL/cm^2{\cdot}min$, column diameter to packing height of 1:15. But to search optimum separation conditions of terbium, it changed the eluent acidity, the loading weight of sample. the composition of sample. In conclusion, acidity was 0.6 N HCl, loading weight of sample was about 5% and composition of sample was $Gd_2O_3(20%)+Tb_4O_7(60%)+Dy_2O_3(20%)$. Moreover purity of separated terbium by ICP-AES analysis was 99.98% in yield of 99.99%.

• Microbiology and Biotechnology Letters
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• v.43 no.3
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• pp.204-211
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• 2015

A bacterial strain capable of hydrolyzing xylan and locust bean gum (LBG) was isolated from the Saemangeum tideland of Korea. Based on the biochemical properties and the 16S rRNA gene sequence, the isolate YB-30 was identified as Bacillus subtilis. Xylanase productivity was increased effectively when B. subtilis YB-30 was grown in the presence of wheat bran, while mannanase productivity was increased drastically when grown in the presence of konjac or LBG. Particularly, maximum mannanase and xylanase activities were detected in the culture filtrate of media containing 3.5% konjac and 1% wheat bran. Both enzyme productivities reached maximum levels in the stationary growth phase. The culture filtrate exhibited the highest activity at 60℃ and pH 6.0 for mannanase and at 55℃ and pH 5.5 for xylanase, respectively. Both enzymes were not stable at high temperatures and xylanase was less stable than mannanase. In addition, wheat bran was hydrolyzed to liberate reducing sugar to a greater extent than rice bran by the culture filtrate because the wheat bran contained more arabinoxylan than the rice bran. Hence, xylanase and mannanase produced by B. subtilis YB-30 have a potential use as feed additive enzymes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.77-82
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• 2004

This paper presents polar converting logic(PCL) of BTT missiles against slowly moving or stationary targets. A guidance commands expressed in rectangular coordinates must be converted in the form of polar coordinates for BTT control. Since conventional PCL has nonlinear and discontinuous function, the missiles may lose controllability when pitch acceleration command equals to zero. Further, roll coupling may have a serious unstabilizing influence on homing guidance with two gimbals seeker. In this paper, a linear homotopy equation is introduced to improve the controllability and a command following performance at midcourse phase. We also design a PCL which is less sensitive to pitch acceleration command so that it may improve the stability of the homing loop. To substantiate our conclusion, results of the computer simulation have been illustrated.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.121-128
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• 1998

In fields of operating or handling a hydrogen isotope facility, and of the technology for nuclear fusion source management, gas chromatography has been used as one of the practical techniques lot separation and enrichment of hydrogen isotopic gases including tritium. Chromatographic separation experiments of the hydrogen isotope mixture (hydrogen, deuterium and tritium) were carried out by use of a commercially available gas chromatograph. An aliquot of gas sample was injected by a specially designed vacuum sampler into the stream of inert carrier gas which went through the separation column under liquid nitrogen temperature. The complete separation of hydrogen isotopic molecules was observed with an alumina adsorbent partially deactivated by coating with 10% manganese chlorine. In addition, fairly good separation conditions were obtained without any appearance of nuclear spin isomers with shorter retention time, which would be available for the practical applications of the hydrogen isotope separation and enrichment.

• Journal of Plant Biotechnology
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• v.4 no.4
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• pp.143-150
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• 2002

A strong oxidative stress-inducible peroxidase promoter (referred to as SWPA2 promoter) was cloned from tell cultures of sweetpotato (Ipomoea batatas) and characterized in transgenic tobacco cultured cells in terms of biotechnological applications. Employing a transient expression assay in tobacco protoplasts, with five different 5'-deletion mutants of the SWPA2 promoter fused to the $\beta$-glucuronidase (GUS) reporter gene, the 1314 bp deletion mutant showed approximately 30 times higher GUS expression than the CaMV 35S promoter. The expression of GUS activity in suspension cultures of transgenic cells derived from transgenic tobacco leaves containing the -1314 bp SWPA2 promoter-GUS fusion was strongly expressed following 15 days of subculture compared to other deletion mutants, suggesting that the 1314 bp SWPA2 promoter will be biotechnologically useful for the development of transgenic cell lines engineered to produce key pharmaceutical proteins. In this respect, we developed transgenic cell lines such as tobacco (Nicotiana tabacum L. BY-2), ginseng (Panax ginseng) and Siberian ginseng (Acanthopanax senticosus) using a SWPA2 promoter to produce a human lactoferrin (hLf) and characterized the hLf production in cultured cells. The hLf production monitored by ELISA analysis in transgenic BY-2 cells was directly increased proportional to cell growth and reached a maximal level (up to 4.3% of total soluble protein) at the stationary phase in suspension cultures. The SWPA2 promoter should result in higher productivity and increased applications of plant cultured cells for the production of high-value recombinant proteins.

• Korean Journal of Microbiology
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• v.37 no.3
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• pp.214-220
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• 2001

To develop the effective composting system, we isolated bacteria that have the abilities to degrade organic matters such as cellulose, carbohydrate, protein and lipid during the compositing of livestock manureAmong 24 strains, 6 bacteria have all the enzymatic activities of protease, amylase, cellulase and lipase.These microorganisms were identified as Corynebacterium varibilis, Bacillus spp., Pseudomonas spinosa,Acetobacter calcoaceticus and Athrobacter cumminsii All the enzymes produced by the bacteria showedactivities at the broad pH range and the maximal activities were obtained at $60^{\circ}C$. It seemed that after theincrease of temperature caused by fermentation of livestock manure, the enzymes started to degrade the rawmaterials, which are added for the control of humidity. However cellulase activity was maximum at $37^{\circ}C$,suggesting that the cellulase-producing bacteria work at an early stage of livestock manure fermentation toprovide the organic material for the growth of other bacteria. The production of the enzymes were growth-associated and maximal activities appeared at the early stationary phase of growth.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.225-230
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• 2011

A bacterium producing the extracellular mannanase and xylanase was isolated from Korean farm soil by successive subcultures in a minimal medium supplemented with palm kernel meal (PKM) and rice bran. The isolate YB-1106 showed 98% similarity with Microbacterium arabinogalactanolyticum on the basis of 16S rRNA gene sequences. The additional carbohydrates including locust bean gum (LBG) and PKM increased the mannanase productivity of the YB-1106, while the xylanase productivity of the isolate was increased by wheat bran, oat spelt xylan, rice bran and xylose. Particularly, maximum mannanase and xylanase activities were obtained in the culture filtrate of tryptic soy broth supplemented with 1% LBG or 2% wheat bran, respectively. Both enzyme activities were produced at stationary growth phase. The mannanase of culture supernatant was the most active at $50^{\circ}C$ and pH 6.0, while xylanase of culture supernatant was the most active at $55^{\circ}C$ and pH 6.5. The predominant products resulting from the mannanase or xylanase hydrolysis were oligosaccharides for LBG or xylan, respectively.

• Proceedings of the Korean Society of Life Science Conference
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• 2000.06a
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• pp.3-8
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• 2000

The complete genome sequence of a Gram-positive bacterium .Bacillus subtilis has recently been reported and it is now clear that more than 50% of its ORFs have no known function (1). To study the global gene expression in B. subtilis at single gene resolution, we have tested the glass DNA microarrays in a step-wise fashion. As a preliminary experiment, we have created arrays of PCR products for 14 ORF whose transcription patterns have been well established through transcriptional mapping analysis. We measured changes in mRNA transcript levels between early exponential and stationary phase by hybridizing fluorescently labeled cDNA (with Cy3-UTP and Cy5-UTP) onto the array. We then compared the microarray data to confirm that the transcription patterns of these genes are well consistent with the known Northern analysis data. Since the preliminary test has been successful, we scaled up the experiments to ${\sim}$94% of the 4,100 annotated ORFs for the complete genome sequence of B. subtilis. Using this whole genomic microarray, we searched genes that are catabolite-repressive and those that are under the control of ${\sigma}^{Y}$, one of the functionally unknown ECF sigma factors. From these results, we here report that we have established DNA microarray techniques that are applicable for the whole genome of B. subtilis.