• Resources Recycling
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• v.17 no.3
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• pp.35-41
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• 2008

The study of coking technology to upgrade oil sand bitumen which is considered as alternative fuel was performed by using thermogravity analyzer and delayed coking reactor(600ml). To analyzed and compared coking characteristics of oil sand bitumen, the reactivities of oil sand bitumen were measured in the TGA. At the temperature conditions of $400{\sim}550^{\circ}C$ and the temperature rising velocity of $50^{\circ}C/min$. the termination time of coking reaction and conversion efficiencies increased with an increase of bed temperature. However the increase rate decreased over $450^{\circ}C$. So the coking reaction with oil sand bitumen might be over $450^{\circ}C$. Also the termination time decreased with increasing the temperature rising velocity. But the content of coke increased with increasing temperature rising velocity. At the experiments in the delayed coker, the temperature condition at maximum oil yield was $475^{\circ}C$ and the fuel properties of oil from coking reaction was almost equal with conventional diesel. It was verified that the coking process might be useful process to upgrade the oil sand bitumem by using API and SIMDAS.

• KSBB Journal
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• v.25 no.4
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• pp.357-362
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• 2010

Green alga, Ulva pertusa kjelmann has been known to be one of the largest pollutants in Korea. Therefore, the efficient pretreatment processes have been required to improve the yields of fermentable sugar. The optimal pretreatment conditions were determined to be $195^{\circ}C$ for 15 min. The sugar yield of glucose and xylose were estimated as 20.5%, and 5.0% respectively, based on theoretical yields. However solid residues were estimated enzymatic digestibility of 90-95% with cellulase loading of 15 FPU/g glucan. This process was proved to generate the low concentration of Hydroxy-Methyl-Furfural (51 ppm), which resulted in ethanol production with 95% of the maximum conversion yield from glucose in the culture of Saccharomyces cerevisiae (ATCC, 24858). This study showed that Ulva pertusa kjellmann can be used as a bioetahnol resource using the high temperature liquefaction process.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.561-569
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• 2023

Furfural is a platform chemical that is produced from xylose, one of the hemicellulose components of lignocellulosic biomass. Furfural can be used as an important feedstock for phenolic compounds or biofuels. In this study, we compared and optimized the conditions for producing furfural from xylose in a batch system using two types of catalysts: sulfuric acid, which is commonly used in the furfural production process, and formic acid, which is an environmentally friendly catalyst. We investigated the effects of xylose initial concentration (10 g/L~100 g/L), reaction temperature (140~200 ℃), sulfuric acid catalyst (1~3 wt%), formic acid catalyst (5~10 wt%), and reaction time on the furfural yield. The optimal conditions according to the type of catalyst were as follows. For sulfuric acid catalyst, 3 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 10min of reaction time resulted in a maximum furfural yield of 59.0%. For formic acid catalyst, 5 wt% of catalyst concentration, 50 g/L of xylose initial concentration, 180 ℃ of temperature, and 150 min of reaction time resulted in a furfural yield of 65.3%.

• Proceedings of the Korean Society of Crop Science Conference
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• 1999.11a
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• pp.145-167
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• 1999

Our self-sufficiency of food has become less than $30{\%}$ and our nation is highly dependant on world's grain market for food. which is unstable in long term due to the world population growth faster than food production. Therefore, it is a great possibility that food might become a political weapon by way of its global shortage. its purchasing difficulty in international free trade market. and the resultant price rising. Our maximal capability of food production has become the most outstanding problem in the dimension of future food security. It would be the utmost scheme for maximal production of food to realize the maximal utilization of arable land through the enlargement of sufficient farming land and the conversion of rotation system for the more grain production. Extensional enlargement of arable land can be positively executed through the development of farming land in domestic and abroad countries. The readjustment of arable land and the installation or irrigation and drainage system can enforce the farming basement for maximal utilization of arable land through the improved rotation between paddy and upland. The prevention policy against farming land encroachment should be strictly executed through grain production encouragement on resting or marginal lands and regulation of utilization conversion for the other than food production on high grade farming lands. It is also required urgently to develope high yielding and high quality varieties through advanced genetic technology for the improvement of unit area yield, especially of wheat, corn. and soybean we import in large quantity The maximal utilization of arable land for the highest production of food can be realized through rational rotation system, the most adaptable crop cultivation on the suitable land, and the most optimal fertilization through the GIS analysis of agricultural environment information on the basis of the computerized soil resource data on super detailed soil maps(1:5000) surveyed plot by plot of whole nation.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.116-122
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• 2007

An efficient enzyme system for the synthesis of L-tyrosine was developed using a fed-batch reactor with continuous feeding of phenol, pyruvate, and ammonia. A thermo- and chemostable tyrosine phenol-lyase from Symbiobacterium toebii was employed as the biocatalyst in this work. The enzyme was produced using a constitutive expression system in Escherichia coli BL21, and prepared as a soluble extract by rapid clarification, involving treatment with 40% methanol in the presence of excess ammonium chloride. The stability of the enzyme was maintained for at least 18 h under the synthesis conditions, including 75 mM phenol at pH 8.5 and $40^{\circ}C$. The fed-batch system (working volume, 0.51) containing 1.0 kU of the enzyme preparation was continuously fed with two substrate preparations: one containing 2.2 M phenol and 2.4 M sodium pyruvate, and the other containing 0.4 mM pyridoxal-5-phosphate and 4M ammonium chloride (pH 8.5). The system produced 130g/I of L-tyrosine within 30h, mostly as precipitated particles, upon continuous feeding of the substrates for 22 h. The maximum conversion yield of L-tyrosine was 94% on the basis of the supplied phenol.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.398-404
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• 1991

- Ethanol production by calcium alginate-immobilized baker's yeast was studied in the continuous shaked-flask reactor (CSFR) using glucose medium as a feed. Immobilized cells were stable at 30~$37^{\circ}C$ and pH 4~8. Fermentation characteristics of immobilized baker's yeast were examined changing the initial glucose concentration employed were 50, 100 and 150 g/l, respectively. It was investigated that the influent glucose concentration and the dilution rate have an influence on the ethanol fermentation characteristics at steady state in continuous culture of immobilized baker's yeast. The optimum conditions for high ethanol productivity and low residual glucose output in ethanol prodution were shown to be 0.2 h ' for the dilution rate and 150 g/l for the influent glucose concentration. The maximum ethanol productivity, ethanol yield, specific growth rate and glucose conversion rate were around 7.12 g/$l\cdot h$, 0.23, 0.366 g/$l\cdot h$ and 78.43, respectively.

• KSBB Journal
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• v.27 no.6
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• pp.341-346
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• 2012

Indican (indoxyl-${\beta}$-D-glucoside) is a colorless natural compound and can be used as a precursor for the production of indigo. This production step only require an enzyme, ${\beta}$-glucosidase, that readily screened from microbial resource by using selective media supplemented with indican as a sole carbon source. Agrobacterium tumefaciens was well grown in this media and thus presumed to produce a related enzyme. The corresponding gene, encoding a protein with a calculated molecular mass of 51 kDa, was cloned and overexpressed as MBP fusion proteins. The purified enzyme was determined to be a dimer and showed the maximum activity for indican at pH 7.0 and $40^{\circ}C$. The kinetic parameters for indican, Km and Vmax, were determined to be 1.4 mM and 373.8 ${\mu}M/min/mg$, respectively. The conversion yield of indican into indigo using this enzyme was about 1.7-1.8 folds higher than that of previously isolated enzyme from Sinorhizobium meliloti. Additionally, this enzyme was able to hydrolyze various ${\beta}$-1,4 glycoside substrates.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.696-703
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• 2015

A gamma-aminobutyric acid (GABA)-producing microorganism was isolated from jeot-gal (anchovy), a Korean fermented seafood. The isolate, A156, produced GABA profusely when incubated in MRS broth with monosodium glutamate (3% (w/v)) at 37℃ for 48 h. A156 was identified as Lactobacillus sakei by 16S rRNA gene sequencing. The GABA conversion yield was 86% as determined by GABase enzyme assay. The gadB gene encoding glutamate decarboxylase (GAD) was cloned by PCR. gadC encoding a glutamate/GABA antiporter was located immediately upstream of gadB. The operon structure of gadCB was confirmed by RT-PCR. gadB was overexpressed in Escherichia coli BL21(DE3) and recombinant GAD was purified. The purified GAD was 54.4 kDa in size by SDS-PAGE. Maximum GAD activity was observed at pH 5.0 and 55℃ and the activity was dependent on pyridoxal 5'-phosphate. The K_m and V_max of GAD were 0.045 mM and 0.011 mM/min, respectively, when glutamate was used as the substrate.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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• pp.17-23
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• 2015

In bioethanol from acid hydrolysis process, neutralization of acid hydrolyzate is essential step, which resulted in dissolved cations in glucose solution. Impact of cations to Saccharomyces cerevisiae in glucose solution was investigated focused on ethanol fermentation. Both potassium and sodium cations decreased the ethanol fermentation and glucose to ethanol conversion as potassium or sodium cations. In sodium cation, more than 1.13 N sodium cation in glucose solution led to ethanol production less than theoretical yield with severe inhibition. In 1.13 N sodium cation concentration, ethanol fermentation was slowed down to reach the maximum ethanol concentration with 48 h fermentation compared with 24 h fermentation in control (no sodium cation in glucose solution). In case of potassium cation, three different levels of potassium led to silimar ethanol concentration even though slight slow down of ethanol fermentation with increasing potassium cation concentration at 12 h fermentation. Sodium cation showed more inhibition than potassium cation as ethanol concentration and glucose consumption by Saccharomyces cerevisiae.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.243-246
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• 2005

A novel esterase showing high enantioselectivity to (S)-ketoprofen ethyl ester was selected from fosmid environmental DNA library which is provided by Microbial Genomic & Applications Center. As a result of Blast search, the gene wasn't registerated in Gene Bank yet. And as we know, conserved domain region of esterase , G-X-S-X-G, wasn't discovered.$^{4)}$ And it is similar to Beta-lactamase. The DNA sequence of cloned esterase include an open reading frame consisting of 1170 bp, designated as EST-Y29, encoding a protein of 389 amino acids with a molecular mass of about 42.8 kDa. And amino acid sequence analysis revealed only a few identity (28%) to tile known esterases/lipases in the databases containing the conserved sequence motifs of esterases/lipases. when being comparison to other esterase revealed , this enzyme seems to be classified as a new member of esterase family. EST-Y29 was functionally overexpressed in a soluble form in E. coli with maximum conversion yield of (S)-ketoprofen at $65^{\circ}C$. This study demonstrates that functional screening combined with the sequential uses of restriction enzymes to exclude already known enzymes is a useful approach for isolating novel enzyme from a metagenome.