• Clean Technology
• /
• v.17 no.4
• /
• pp.389-394
• /
• 2011

A compact adsorption-based process for removal of carbon dioxide and nitrogen from natural gas has been discussed. Among the adsorption-based processes, especially, the pressure swing adsorption (PSA) process has been a suitable unit operation for the purification and separation of gas because of low operation energy and cost. A step cycle is made up of pressurization, feed, equalization, blowdown and rinse. In this work, the PSA process is composed of zeolite 13X and carbon molecular sieve (CMS) for removal of carbon dioxide and nitrogen from mixed gas containing $CH_4/CO_2/N_2$ (75:21:4 vol%). A CMS selectively removes carbon dioxide and a zeolite 13X separates nitrogen from methane. CMS is investigated experimentally due to the high throughput of the faster diffusing component ($CO_2$). The gas composition of top, bottom and feed tank was measured with the gas chromatography (GC) using TCD detector, helium as carrier gas and packed column for analysis of methane, carbon dioxide, and nitrogen.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.9 no.1
• /
• pp.15-22
• /
• 1980

In this study, two species of algae, Ecklonia stolonifera, Sargassum thunbergii and one species of marine plant, Zostera marina(rhizoid and stem) were collected and extamined to determine the extractability of water soluble protein and the influences of various factors including extraction time, temperature, ratio of sample vs solvent and pH upon the extractability were tested. The effects of precipitation treatments for isolation of algal protein from the extracts(TCA treatment, methanol treatment and pH control) were also tested. Amino nitrogen and total nitrogen of purified samples made by obtained optimum conditions were estimated. The effect of the ratio of sample vs solvent on extractability differed from species to species which was enhances at 1:100(w/v) in Sargassum thunbergii and Zostera marina while 1:150(w/v) for Ecklonia stolonifera. The effect of extraction time and temperature was revealed differently in all species which might be considered to be caused by differences in the constitution of algal tissues. But in case of TCA insoluble nitrogen, it was showed the maximum extractability at $40-50^{\circ}C$ for 1 hour extraction. The optimum pH for the ext action of total nitrogen was 9-12 while the optimum pH was 6-7 for TCA insoluble nitrogen. And the pH control appeared to be most effective in the influence of precipitation treatment for isolation of algal protein.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.5
• /
• pp.35-41
• /
• 2004

In computational study on RF(Radio Frequency) plasmas, a 1D fluid models with an advantage of a short computational time are often adopted. However, in order to obtain realistic calculation results under a typical chamber geometry with unequal-sized electrodes, modeling of the plasma space is an issue to be investigated. In this paper, it is focused on that how much a 1D model can approximate a 2D model. 1D fluid models with unequal-sized electrodes, which have spherical and frustum geometry systems, were developed and their results were compared with those of 2D model with Gaseous Electronic Conference cell structure. Behavior of $N_2$ RF plasmas has been simulated using 1D and 2D fluid models and a technique to take account of unequal-sized electrodes in a 1D fluid models has been examined. Features of the plasma density and the electric potential were discussed as characteristic quantities representing the asymmetry of the chamber geometry.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.5
• /
• pp.600-605
• /
• 2006

B. subtilis JM3 pretense from naturally fermented anchovy sauce was purified in $40{\sim}60%$ ammonium sulfate fraction. In order to accelerate the fermentation of anchovy sauce,2% and 4% of crude B. subtilis JM3 protease were added to 6 month-fermented anchovy sauces, respectively and then the various quality characteristics such as pH, lactic acid, amino-nitrogen, VBN, browning and hydrolysis degree, VBN, and sensory evaluation were analyzed at different storage times. pH was constant during storage time in all samples, whereas lactic acid contents of anchovy sauces hydrolyzed by 2% and 4% proteases were higher than that of control. The amino-nitrogen and volatile basic nitrogen contents of anchovy sauce with 2% and 4% proteases were twice higher than those of control. Anchovy sauces with 2% and 4% pretense increased the hydrolysis rate by 27% and 32%, respectively. Browning degree of anchovy sauce with 4% was higher than those of 2% and control. Anchovy sauce with 2% and 4% proteases was good in sensory evaluation of color, aroma, and taste attributes.

• The Korean Journal of Pesticide Science
• /
• v.14 no.4
• /
• pp.361-370
• /
• 2010

Considering the efficiencies of the preparation process at each stage obtained in previous studies, the analytical determination method was established for multi-pesticide residues in soils. It consist of the acetone-extraction, the dichloromethane-partition, the Florisil or silica-gel chromatography and the gas chromatography analysis equipped with the electron capture detector and the nitrogen-phosphorus detector. In the soil recovery test by Florisil clean-up system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 165 pesticides for paddy soil, 169 pesticides for upland soil and 159 pesticides in both soils through the tested 183 pesticides. And in the soil recovery test by silica-gel system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 154 pesticides for paddy soil, 145 pesticides for upland soil, and 134 pesticides in both soils.

• Korean Journal of Microbiology
• /
• v.39 no.1
• /
• pp.1-7
• /
• 2003

The aim of this work was to investigate the characterization and sequence of catechol 2,3-dioxygenase isolated from Delfia sp. JK-2, which could utilize aniline as sole carbon, nitrogen and energy source. In initial experiments, several characteristics of C2,3O separated with ammonium sulfate precipitation, DEAE-sepharose were investigated. Specific activity of C2,3O was approximately 4.72 unit/mg. C2,3O demonstrated its enzyme activity to other substrates, catechol and 4-methylcatechol. The optimum temperature of C2,3O was $$Cu^{2+}$^{\circ}C$, and the optimal pH was approximately 8. Metal ions such as $Ag^{+}$, $Hg^{+}$, and $Cu^{2+}$ showed inhibitory effect on the activity of C2,3O. Molecular weight of the enzyme was determined to approximately 35 kDa by SDS-PAGE. N-terminal amino acid sequence of C2,3O was analyzed as $^{1}MGVMRIG-HASLKVMDMDA- AVRHYENV^{26}$, and exhibited high sequence homology with that of C2,30 from Pseudomonas sp. AW-2, Comamonas sp. JS765, Comamonas testosteroni and Burkholderia sp. RPO07. PCR product was amplified with the primers derived from N-terminal amino acid sequence. In this work, we found that the amino acid sequence of Delftia sp. JK-2 showed high sequence homology of C2,3O from Pseudomonas sp. AW-2 (100%) and Comamonas sp. JS765 (97%).

• Microbiology and Biotechnology Letters
• /
• v.31 no.3
• /
• pp.250-256
• /
• 2003

Lactic acid bacteria with amylolytic and acid producing activities can ferment starch directly to lactic acid thereby producing a monomer for the production of biodegradable poly lactic acid (PLA). In this study, the strain producing L-lactic acid from soluble starch was isolated from Nuruk. The isolated strain was identified as Enterococcus sp. through its morphological, cultural, biochemical characteristics as well as the 16S rDNA sequence analysis, and named Enterococcus sp. JA-27. Enterococcus sp. JA-27 produced exclusively L-lactic acid from soluble starch as a carbon source. The optimal conditions for the maximum production of L-lactic acid from Enterococcus sp. JA-27 were 30 C, pH 8, 1.5 % soluble starch as a substrate and 3.5 % tryptone as a nitrogen source, 0.1 % $K_2$$HPO_4$, 0.04 % $MgSO_4$. $7H_2$O, 0.014 % $MnSO_4$$.$4$H_2O$, 0.004% $FeSO_4$$.$$7H_2$O. Batch and fed batch culture were carried out and the former was more effective. L-Lactic acid production in the optimum medium was significantly increased in a 7 L jar fermenter, where the maximum L-lactic acid concentration was 3 g/L. For the purification of lactic acid in fermented broth, two stage ionexchange column chromatographies were employed and finally identified by HPLC.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.4
• /
• pp.596-601
• /
• 2020

Silicon carbide is considered a potentially useful material for high-temperature electronic devices because of its large band gap energy and p-type or n-type conduction that can be controlled by impurity doping. Accordingly, the thermoelectric properties of -SiC powder prepared by refined diatomite were investigated for high value-added applications of natural diatomite. -SiC powder was synthesized by a carbothermal reduction of the SiO₂ in refined diatomite using carbon black. An acid-treatment process was then performed to eliminate the remaining impurities (Fe, Ca, etc.). n-Type semiconductors were fabricated by sintering the pressed powder at 2000℃ for 1~5h in an N2 atmosphere. The electrical conductivity increased with increasing sintering time, which might be due to an increase in carrier concentration and improvement in grain-to-grain connectivity. The carrier compensation effect caused by the remaining acceptor impurities (Al, etc.) in the obtained -SiC had a deleterious influence on the electrical conductivity. The absolute value of the Seebeck coefficient increased with increasing sintering time, which might be due to a decrease in the stacking fault density accompanied by grain or crystallite growth. On the other hand, the power factor, which reflects the thermoelectric conversion efficiency of the present work, was slightly lower than that of the porous SiC semiconductors fabricated by conventional high-purity -SiC powder, it can be stated that the thermoelectric properties could be improved further by precise control of an acid-treatment process.

• Microbiology and Biotechnology Letters
• /
• v.35 no.2
• /
• pp.128-134
• /
• 2007

Previously, we isolated plant growth promoting rhizobacterium (PGPR) Bacillus licheniformis K11 which could produce auxin, cellulase and siderophore. The siderophore of B. licheniformis K11 $(siderophore_{K11})$ was determined to be a catechol type siderophore which is produced generally by Bacillus spp. B. licheniformis K11 could produce the siderophore most highly after 96 h of incubation under nutrient broth at $20^{\circ}C$ with initial pH 9.0. For the production of the $siderophore_{K11}$, trehalose and $NH_4Cl$ were the best carbon and nitrogen sources in Davis minimal medium, respectively. The $siderophore_{K11}$ was Produced in M9 medium (pH 9.0) after 4 days at $20^{\circ}C$, and purified from culture broth of B. licheniformis K11 by using Amberlite XAD-2, Sephadex LH-20 column chromatography, and reversed-phase HPLC. The $siderophore_{K11}$ had the biocontrol activity against spore germination of P. capsici and F. oxysporum on potato dextrose agar (PDA). The results indicate that the $siderophore_{K11}$ is an antifungal mechanism of B. licheniformis K11 against phytopathogenic fungi.

• Applied Biological Chemistry
• /
• v.50 no.1
• /
• pp.18-22
• /
• 2007

The optimum production condition for the antibiotic from Bacillus thuringiensis BK4 was determined, and the suppression rate of Fusarium-wilt by the butanol-extracted antibiotic was verified by employing tomatoes in vitro and in vivo pot tests. Cell growth and antifungal activity were the best when 0.5% xylose and 0.2% peptone No.3 were given as carbon and nitrogen sources, respectively, in the presence of 5mM $CaCl_2$. The partially purified antibiotic successfully prevented Fusarium oxysporum pathogen in pot experiments. When the pots were treated with both live cells and the partially purified antibiotic, an additive-effect was seen in the suppression of Fusarium-wilt, but synergistic effect was not detected. The antibiotic, denoted BK4, purified by Sephadex LH-20 column chromatography was eluted with a single peak at a retention time of 38 min. on prep-HPLC; Minimum inhibition concentration of the homogenous antibiotic was determined to be 50${\mu}$g/ml.