• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.309-313
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• 2007

In Activated Sludge Model, COD fraction of primary settled municipal wastewater was a very important parameter. In this study, the COD fraction was determined using the oxygen utilization rate experiments. Readily biodegradable COD ($S_S$) fraction was observed about 29.7% of influent TCOD. $S_I$, $X_I$, and $X_S$ were analyzed to be 7.6%, 7.3%, and 55.4% of TCOD, respectively. The model used in this study was developed based on ASM3 and modified Bio-P module in order to simulate the existing BNR process. Parameter estimation results showed that $Y_{STO,O2}$, $Y_{STO,NO}$, $Y_{H,O2}$, $Y_{H,NO}$, $Y_{PO4}$, ${\mu}_H$, $b_H$, ${\mu}_A$, $q_{PHA}$, $q_{PP}$ and ${\mu}_{PAO}$ were 0.7, 0.64, 0.61, 0.48, 0.31, 3.9, 0.1, 1.35, 4.98, 1.8 and 0.59, respectively. Using the presented model and the estimated parameters, the simulation of the existing BNR process was successfully conducted.

• Microbiology and Biotechnology Letters
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• v.17 no.1
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• pp.69-73
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• 1989

Cellular autolytic enzyme was isolated from the supernatant fluid of exponentially growing cuiture of Cl. butyricum ID-113. The autolysin was partially pruified by ammonium sulfate fractionation, chromatography on DEAE-Sephadex A-50 and gel filtration through Sephadex G-200. This autolytic enzyme lysed SDS-treated cell wall fractions of Cl. butyricum ID, but not whole cells at all. Its optimum pH and temperature were 5.0 and 37$^{\circ}C$, respectively. This enzyme was relatively stable at neutral pH, but sensitive to heat treatment. Enzyme activity was not influenced by the addition of various divalent cation, but inhibited by Cu$^{++}$.

• Proceedings of the Korean Environmental Health Society Conference
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• 2003.06a
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• pp.140-143
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• 2003

This research was to determine and compare the inactivation of total coliform as the indicator organism with chlorine, chlorine dioxide and ozone for drinking water treatment. The inactivation of total coliform was experimentally analyzed for the dose of disinfectant, contact time, pH, Temperature and DOC. The experiments for the characterization of inactivation were performed in a series of batch processes with the total coliform as a general indicator organism based on chlorine, chlorine dioxide and ozone as disinfectants. The nearly 2.4, 3.0, 3.9 log inactivation of total coliform killed by injecting 1mg/L at 5 minutes for chlorine, chlorine dioxide and ozone. For the inactivation of 99.9%, Disinfectants required were 1.70, 1.00 and 0.60 mg/L for chlorine, chlorine dioxide and ozone, respectively. The bactericidal effects of disinfectants were decreased as the pH increased in the range of pH 6-9. The influence of pH change on the killing effect of chlorine dioxide was not strong, but that on ozone and free chlorine was sensitive. The bactericidal effects of the disinfectants were increased as the temperature increase. The activation energies were 36,053, 29,822, 24,906 J/mol of chlorine, chlorine dioxide, ozone for coliforms. The inactivation effects were shown in the lowest order of chlorine, chlorine dioxide and ozone.

• Journal of Sensor Science and Technology
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• v.28 no.2
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• pp.76-80
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• 2019

The characteristics of a titanium oxide layer prepared using a plasma electrolytic oxidation (PEO) process were investigated, using an extended gate ion sensitive field effect transistor (EG-ISFET) to confirm the layer's capability to react with hydrogen ions. The surface morphology and element distribution of the PEO-processed titanium oxide were observed and analyzed using field-emission scanning-electron microscopy (FE-SEM) and energy-distribution spectroscopy (EDS). The titanium oxide prepared by the PEO process was utilized as a hydrogen-ion sensing membrane and an extended gate insulator. A commercially available n-channel enhancement MOS-FET (metal-oxide-semiconductor FET) played a role as a transducer. The responses of the PEO-processed titanium oxide to different pH solutions were analyzed. The output drain current was linearly related to the pH solutions in the range of pH 4 to pH 12. It was confirmed that the titanium-oxide layer prepared by the PEO process could feasibly be used as a hydrogen-ion-sensing membrane for EGFET measurements.

• 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.

• Applied Biological Chemistry
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• v.36 no.4
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• pp.260-264
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• 1993

In order to determine the stability of ginseng components in this salt concentration when used to ginseng as additive ingredient of sauces or seasonings, we study on the content and charactristic of ginsenosides and changes in pH and color, ginseng tail and ginseng extract were treated with various concentration of NaCl solution. In this experiment, extract of ginseng tail were increased in pH as NaCl concentration were increased, but ginseng extract have not changed evidently. The both solution were decreased in color as the salt concentration were increased. Yield of n-butanol extract was decreased in 5% NaCl concentration, while it was increased in the above concentration, and ginseng extract was changed higher than ginseng tail. Ginsenosides content were increased in 5% NaCl concentration, both $ginsenosied-Rb_1$, $-Rb_2$, -Rc, -Rd of diol line and ginsenoside-Re of triol line and increased in above NaCl concentration. Especially ginsenoside-Re showed to sensitive response to the changes of the salt concentration.

• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.124-128
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• 2003

In order to isolate and characterize a novel fungal strain capable of producing cellulase, each samples of the old rice straw, soil, and the old tree were screened by congo red test. One of the fungi screened has been identified as Aspergillus tubingensis strain from the results of the phylogenic analysis based on partial DNA sequence and the basis of its biochemical properties. A carboxymethyl cellulase activity of the strain was higher than that of A. oryzae KCTC 6291. In CMCase activity measurement, it wasn't sensitive about pH 2.0, 3.0, 4.0, but the enzyme was more stable than A. oryzae under the various pH and temperature conditions and the enzyme activity was more similar to neutrality and alkali. Therefore, it could be suggested that the isolated strain has a potential possibility for the developing of the probiotics.

• Journal of Life Science
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• v.9 no.1
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• pp.111-120
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• 1999

A bacteriocin-producing strain, J-105, was isolated from Kimchi and identified as Lactococcus sp. The optimum conditions for the bacteriocin production from the isolated microorganism were evaluated. For maximum yield of bacteriocin from Lactotoccus sp. J-105, the cell should be harvested at the early stationary phase and temperature, pH and NaCl concentration should be $25^{\circ}C$, pH 8.0 and without the addition of NaCl, respectively. Maltose should be used as a carbon source and organic nitrogen such as polypeptone should be used as a nitrogen source for the best yield. The bacteriocin from isolate was inhibitory against Acetobacter aceti, Bacillus subtilis and several strains of lactic acid bacteria. The bacteriocin of J-105 was sensitive to pepsin, but stable for heat treatment. It was stable even at autoclaving temperature for 15 min.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.238-238
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• 2011

Ion sensitive field effect transistor (ISFET)는 용액의 이온 농도를 측정하는 반도체 센서로, 1970년 Bergveld에 의해 처음으로 제안되었다. ISFET가 제안된 이래로, 제조공정이 간단하고 감지막의 감지 특성 평가가 용이한 electrolyte-insulator-semiconductor (EIS) pH센서 또한 지속적으로 연구되었다. EIS pH센서는 작은 소자 크기, 견고한 구조, 빠른 응답속도와 CMOS공정과의 호환성이 좋다는 장점이 있다. EIS 또는 ISFET 센서를 이용하여 생물학적 요소의 신호 감지 특성을 평가함에 있어 소자의 signal to noise 비율이 우수해야 한다. EIS pH센서의 높은 signal to noise 비율을 얻기 위해, 소자의 표면적을 증가시키거나 감지막으로 유전상수가 높은 물질을 사용하여 출력 특성을 향상시켜야 한다. 본 연구에서는 trench구조와 SiO2/HfO2/Al2O3 (OHA) 적층 감지막을 갖는 EIS pH센서를 제작하여 출력 특성을 증가시키는 실험을 실시하였다. 120 nm, 380 nm, 780 nm의 다양한 깊이를 가진 trench를 형성하였으며, trench 깊이에 따른 출력특성을 비교하였다. 또한, 제작된 EIS 소자의 pH감지 특성을 분석하였다. 제작된 EIS소자의 감지막 중 SiO2는 Si와 high-k물질의 계면 상태를 보완하기 위한 완충막으로 성장되었고, HfO2는 높은 유전상수를 가지고 있어 signal to noise 비율을 향상시키는 물질로 증착되었다. 최종적으로 Al2O3는 pH용액과의 화학적 손상을 막기 위한 물질로 증착되었다. 실험 결과, trench 깊이가 깊어질수록 출력값이 증가하였고 이는 signal to noise 비율이 향상되는 것을 의미한다. 결론적으로 trench 형성을 통한 표면적 증가와 high-k물질을 적층한 감지막으로 인해 높은 출력 특성을 갖는 우수한 EIS 바이오센서를 제작할 수 있었다.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.461-468
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• 2016

In recent years, various naturally occurring defence peptides such as plectasin have attracted considerable research interest because they could serve as alternatives to antibiotics. However, the production of plectasin from natural microorganisms is still not commercially feasible because of its low expression levels and weak stability. A tandemly arrayed plectasin gene (1,002 bp) from Pseudoplectania nigrella was generated using the isoschizomer construction method, and was inserted into the pPICZαA vector and expressed in Pichia pastoris. The selected P. pastoris strain yielded 143 μg/ml recombinant plectasin (Ple) under the control of the methanol-inducible alcohol oxidase 1 (AOX1) promoter. Ple was estimated by SDS-PAGE to be 41 kDa. In vitro studies have shown that Ple efficiently inhibited the growth of several gram-positive bacteria such as Streptococcus suis and Staphylococcus aureus. S. suis is the most sensitive bacterial species to Ple, with a minimum inhibitory concentration (MIC) of 4 μg/ml. Importantly, Ple exhibited resistance to pepsin but it was quite sensitive to trypsin and maintained antimicrobial activity over a wide pH range (pH 2.0 to 10.0). P. pastoris offers an attractive system for the cost-effective production of Ple. The antimicrobial activity of Ple suggested that it could be a potential alternative to antibiotics against S. suis and S. aureus infections.