• Applied Biological Chemistry
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• v.19 no.3
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• pp.130-138
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• 1976

In order to utilize the agricultural waste products, two strains of mold producing powerful cellulolytic enzyme were sereened from various soils, composts, rotten wood and others. The optimum condition of cellulase production was studied. The results obtained were summarized as follows. 1. Two strains of mold which showed remarkably high cellulolytic activity were identified as Aspergillus niger-SM 6 and Trichoderma viride-SM 10. 2. The highest cellulase production was obtained at pH 5.0-6.0 in 5 days. 3. Cellulase production in strain Aspergillus niger-SM 6 increased with the addition of C.M.C., $(NH_4)_2SO_4$, C.S.L., orange peel powder and rice hull. The rice hull, treated with 3N NaOH at $120^{\circ}C$ for 15 min. and neutralized with various acids, was used. Up to 50% of wheat bran could be substituted by the treated rice hull without any decrease of cellulase activity. 4. In the strain of Trichoderma viride-SM 10, cellulase production increased with the addition of C.M.C., $NH_4NO_3$, Vitamin-free casamino acid and orange peel powder, while the other carbon, nitrogen, phosphate sources, natural nutrients and organic substances gave no remarkable effect.

• Applied Biological Chemistry
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• v.50 no.2
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• pp.87-94
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• 2007

A bacterium which has high enzymatic activities such as amylase, cellulase and protease was isolated from Korean traditional soybean food, doenjang. The isolated bacterium was identified to Bacillus subtilis HS25 by the test of morphological and biochemical properties according to Bergey's Manual of Systematic Bacteriology and API 50 CHL kit, and by the 16S rDNA sequence. The isolated B. subtilis HS25 had a potent antibacterial activity against food born causative or pathogenic bacteria. B. subtilis HS25 is endospore forming cell and contained flagella and abundant viscous material at the out layer of cell wall. It was rod type bacterium $(0.5{\sim}0.8{\times}3{\sim}5{\mu}m)$ having biochemical characteristics such as gram staining(+), catalase(+), oxidase(-) and hydrolysis of esculin(+). The optimal medium compositions for production of antibacterial substance in the B. subtilis HS25 were 1% of soluble starch, 0.5% of yeast extract, 0.5% of peptone and 0.05% of MgCl$_2{\cdot}6H_{2}O$. The optimum temperature and pH of the growth of the B. subtilis HS25 was 35$^{\circ}C$ and pH 7.5, respectively. The antibacterial activity was more high in neutral to a little alkaline pH (6.5-10.5) than in acidic pH. The optimal shaking speed to grow and to produce antibacterial substance of the B. subtilis HS25 was 160${\sim}$200 rpm. The optimal culture time for antibacterial activities of the bacterium were shown to be in the range of 12-36 hr.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.255-260
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• 2007

This study was conducted to isolate and identify bacteria producing xylanase and cellulase from spent mushroom substrates and to determine the optimal medium conditions for their growth. Bacteria showing high xylanase and carboxymethyl cellulase activities and low protease and amylase activities were strain 201-3 and strain 206-3. Strain 201-3 was identified as Enterobacter ludwigii and named Ent. ludwigii KU201-3. 206-3 was identified as Bacillus cereus and named B. cereus KU206-3. The optimal medium condition of Ent. ludwigii KU201-3 was obtained when 1%(w/v) of soybean meal and 3%(w/v) of sucrose were used as nitrogen and carbon source, respectively. That of B. cereus KU206-3 was obtained when 3%(w/v) of soybean meal and 1%(w/v) of molasses were used as nitrogen and carbon sources, respectively.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.390-399
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• 2012

Endoglucanase gene egIV was cloned from Trichoderma viride AS 3.3711, an important cellulose-producing fungus, by using an RT-PCR protocol. The egIV cDNA is 1,297 bp in length and contains a 1,035 bp open reading frame encoding a 344 amino acid protein with an estimated molecular mass of 35.5 kDa and isoelectronic point (pI) of 5.29. The expression of gene egIV in T. viride AS 3.3711 could be induced by sucrose, corn straw, carboxymethylcellulose (CMC), or microcrystalline cellulose, but especially by CMC. The transcripts of egIV were regulated under these substrates, but the expression level of the egIV gene could be inhibited by glucose and fructose. Three recombinant vectors, pYES2-xegIV, $pYES2M{\alpha}$-egIV, and $pYES2M{\alpha}$-xegIV, were constructed to express the egIV gene in Saccharomyces cerevisiae H158. The CMCase activity of yeast transformants $IpYES2M{\alpha}$-xegIV was higher than that of transformant IpYES2-xegIV or $IpYES2M{\alpha}$-egIV, with the highest activity of 0.13 U/ml at induction for 48 h, illustrating that the modified egIV gene could enhance CMCase activity and that $MF{\alpha}$ signal peptide from S. cerevisiae could regulate exogenous gene expression more effectively in S. cerevisiae. The recombinant EGIV enzyme was stable at pH 3.5 to 7.5 and temperature of $35^{\circ}C$ to $65^{\circ}C$. The optimal reaction condition for EGIV enzyme activity was at the temperature of $55^{\circ}C$, pH of 5.0, 0.75 mM $Ba^{2+}$, and using CMC as substrate. Under these conditions, the highest activity of EGIV enzyme in transformant $IpYES2M{\alpha}$-xegIV was 0.18 U/ml. These properties would provide technical parameters for utilizing cellulose in industrial bioethanol production.

• Journal of Korean Society of Forest Science
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• v.95 no.6
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• pp.729-734
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• 2006

This paper aimed to suggest decision-making method for forest management planning using integer programming. Thus, the study examined 85 stands consisting of Korean pine, Japanese larch and oak stands-all of which were at the most suitable time for tending, selection thinning, commercial thinning and final cutting-in the experimental forest of Kangwon National University. The forest management model comprised one objective function, maximizing harvest volume in each stand according to tree species and the kinds of practices, and seven constraints: frequency and stands of practices, minimum and maximum yields, even yields, maximum production, and decision-making varialbes. Besides, the entire period intended by the study was 10 years, divided into 5 management periods. In conclusion, the forest management planning model using integer programming proved that among 85 stands, forest practices were conducted over 68 stands (202.8 ha), producing the total harveted volume of $20,000m^3$, while the rest was reserved. This case study could help make decisions on whether and when the forest practices and harvests could be done in a specific condition.

• Journal of the Korean Geographical Society
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• v.46 no.3
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• pp.277-290
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• 2011

Changes of the characteristics in summer rainfall in the Republic of Korea by the regime shift and their causes were examined by analyzing long-term observational data. There has been an abrupt increase in rainfall variability since 1998, which was mainly due to the enhanced rainfall during August~September, although the gradual increase was also detected in June~July. In June~July, the enhanced rainfall developed as a band type covering the whole East Asia while in August~September, it is only found over the Republic of Korea with the greatest increase of 130 mm over Seoul and Gyeonggi area. The two intensified anticyclonic anomalies over the north-northwest/east of the Republic of Korea resulted in producing northerlies/southeasterlies, transporting cold/warm-wet air flows, respectively. The center of the convergence zone from the two separate systems located in the Republic of Korea, leading to a favorable condition for the development of the extreme rainfall. The enhanced barotropic anticyclonic anomalies also affected in warming the sea surface temperature anomalies covering from the eastern coast of East Asia to North Pacific Ocean, which in turn leaded to enhance warm air transporting back to the Republic of Korea.

• Journal of the Korean Geotechnical Society
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• v.34 no.6
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• pp.49-59
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• 2018

When a tracked vehicle travels off-road, shearing action and ground sinkage occur on the soil-track interface and severely affect tractive performance of the tracked vehicle. Especially, the ground sinkage, which is induced by vehicle's weight (hereinafter referred to as static sinkage) and longitudinal forces in the direction of travel producing slip (hereinafter referred to as slip sinkage), develops soil resistance, directly restricting the tractive performance of an off-road tracked vehicle. Thus, to assess the tractive performance of an off-road tracked vehicle, it is imperative to take both of static sinkage and slip sinkage into consideration. In this research, a series of model track experiments was conducted to investigate the slip sinkage which has not been clarified. Experiment results showed that the slip sinkage increased with increasing the slip ratio, but the increasing rate gradually decreased. Also, the slip sinkage was found to increase as relative density of soil decreased and imposed vertical load increased. From the experiment results, the normalized slip sinkage defined as slip sinkage to static sinkage calculated in the identical condition was investigated, and an empirical equation for the slip sinkage was developed in terms of slip ratio, which allows vehicle operators to predict the slip sinkage in a given soil and operating conditions.

• KSBB Journal
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• v.10 no.4
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• pp.349-356
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• 1995

To produce PHA(polyhydroxyalkanoic acid) from microbr, dozens of microorganism have been screened from sewage sludge. Selected a strain HJ out of 50 strains of PHA producing bacteria has a capability of accumulating large amounts of PHB/HV copolymer when grown in batch culture with a single carbon source (glucose) that was not generally considered as precursor of hydroxyvalerate monomer unit. The strain HJ was identified as the genus Pseudomonas with respect to morphological, cultural, and biochemical characteristics. The optimal temperature and pH for cell growth were $37^{\circ}C$ and 7.0. The optimal medium compositions for cell growth were glucose 1% as a carbon source, (NH4) 2SO4 0.2% as a nitrogen source, K2HPO4 0.3%, and KH2PO4 0.45%. TO investigate she optimal condition for PHA production two-step cultivation method was employed. PHA production was inducted by deficiency of NH4+, SO4-2, Mg+2. Besides carbon source, deficiency of all nutrients stimulated PHA productivity but deficiency of NH4+ stimulated the most HV monomer content. The highest PHA production was C/N molar ratio 95.2. Pseudomonas sp. HJ was also able to pyoduc PHB/HV copolymer when cultivated on alkane, alkanoate, alcohol as carbon sources. The contents of PHA and she proportions of hydroxyvalerate monomer units varied depending on the carbon sources. Especially Pseudomonas sp. HJ was able to incorporate hydroxyvalerate into PHB/HV to level as high as from 49 to 74 mol% when grown in a medium containing hexadecane and propionate. The purified PHA was identified PHB/HV copolymer by HNMR analysis.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.739-746
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• 2008

The aim of this study is finding the optimal design parameters and the optimal operation variables of a reactive distillation column. Different from steady state optimization, dynamic optimization makes it possible considering operation ability as well as design problems at process design step. For performing dynamic optimization, dynamic simulation should be done first. If dynamic simulation is already finished, dynamic optimization can be performed with less effort than that of dynamic simulation.Reactive distillation systems involving reaction and separation in a single unit have the potential to reduce capital and operating costs, particularly when reaction have conversion constraint or when azeotropes exist making conventional separation difficult and expensive. This study here present work on the continuous distillation process, the homogeneous catalyzed esterification of methanol and acetic acid, the synthesis of methyl acetate. Based on an equilibrium stage model of a reactive distillation column a dynamic optimization problem was formulated and solved. And the results were verified by performing dynamic simulation and showing the variation of conversion and purity as the variation of the operation variables. As the results of dynamic optimization, this study found optimal feed ratio, reflux ratio and reboiler duty of this system. And as this study applied it to dynamic simulations the dynamic characteristics of a reactive distillation column are showed under optimal operating condition.

• Clean Technology
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• v.20 no.1
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• pp.57-63
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• 2014

In this work, we performed the methanation with steam and synthesis gas of a low $H_2/CO$ ratio to develop a process for producing SNG (synthetic natural gas). In this experiment conditions, the water gas shift reaction and the methanation reaction take place at the same time, and insufficient supply of steam might cause the deactivation of the catalyst. Therefore, the reaction characteristics with the amount of steam was performed, and the methanation on syngas containing $CO_2$ of the high concentration were studied. As a result, the temperature in the catalyst bed decreased by the supply of steam, and the methanation and the water gas shift reaction occurred at the same time. Although methane yield slightly decreased at the methanation using syngas containing $CO_2$ of the high concentration, the long-term operation (1,000 h) in the experimental conditions of this study indicates that this condition is suitable for the new commercial scale SNG process.