• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.3
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• pp.179-182
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• 2001

Porcine liver esterase was immobilized in polyacrylamide gel for the enantioselective production of levofloxacin from ofloxacin butyl ester. The initial activity of immobilized esterase was found to be significantly affected by the polyacrylamide gel composition. The optimum concentrations of monomer and crosslinker were determined to be 20% and 8.3%, respectively. The activity of immobilized esterase was 55.4% compared to a free enzyme. Enantiomeric excess was maintained at 60%, almost the same level as that of free enzyme. In addition, the immobilized esterase could be used repeatedly up to 10 times without experiencing any severe loss of activity and enantioselectivity.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.205-211
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• 2004

A 16S rDNA clone library was generated to investigate the bacterial diversity in tidal flat sediment in Ganghwa Island, Republic of Korea. A total of 103 clones were sequenced and analyzed by comprehensive phylogenetic analyses. No clones were identical to any of known 16S rRNA sequences in public databases. Sequenced clones fell into thirteen lineages of the domain Bacteria: the alpha, beta, gamma, delta, and epsilon Proteobacteria, Actinobacteria, CFB group, Chloroflexi, Acidobacteria, Planctomycetes, Verrucomicrobia, and known uncultured candidate divisions (OP11, BRC1, KSB1, and WS1). Two clones were not associated with any known bacterial divisions. The majority of clones belonged to the gamma and delta Proteobacteria (46.7%). Clones of Actinobacteria were distantly related to known taxa. It is evident from 16S rDNA-based community analysis that the bacterial community in tidal flat sediment is remarkably diverse and unique among other marine environments examined so far.

• Environmental Engineering Research
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• v.25 no.4
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• pp.597-604
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• 2020

In the present study, the application of sequential biological and photocatalytic process was evaluated as a feasible process for the degradation of imidacloprid (IMI) in soil. Photocatalysis was carried out as a post and pre-treatment to the biological process as Microbial Photocatalytic (MP) and Photocatalytic Microbial (PM), respectively, to enhance the degradation and mineralization of IMI in soil. By both the processes, there was an enhancement in the percentage degradation of IMI i.e 86.2% for PM and 94.6% for MP process. The obtained results indicate that MP process is apparently more efficient in degradation of IMI which was observed with 15 days of biological treatment followed by 18 h of photocatalytic degradation (15 d + 18 h). The present work also reveals that though the difference in terms of the degradation of IMI after 5 d + 18 h, 10 d + 18 h & 15 d+ 18 h of MP process is not drastic, yet significant variation has been observed in terms of mineralization that truly signifies the removal of IMI from the soil. The LC analysis has shown that the intermediates formed during MP process are more and smaller in comparison to PM process, which further provides evidence that MP process is better than PM process for effective degradation of IMI in soil.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.459-463
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• 1997

In this paper, we present the elimination of ECG artifact from the polysomnographic EEG and EOG. The idea of this method is that the ECG synchronized EEG segment is detected from ECG and regard samples of that segment a missing signal. After this, we used two interpolation methods to recover the missing segment. One is the Lagrange Polynomial Interpolation Method and the other is the Least Square Error AR Interpolation method. We tested those methods by applying to simulated signals. AR methods works well enough to reject the artifact about 10% of the main artifact level. We practically applied to real EEG and EOG signals. We also developed the algorithm to detect whether the artifact level is high or not. If the artifact level is high, then the interpolations are applied.

• Korea-Australia Rheology Journal
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• v.17 no.2
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• pp.79-85
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• 2005

Aqueous mixtures of hyaluronic acid and poly(vinyl alcohol) system and hydrogels thereof were introduced to obtain new bioartificial materials that have excellent mechanical properties, biocompatibility and enhanced rheological properties. The interactions between hyaluronic acid and poly(vinyl alcohol) and/or borax were investigated by rheological measurements. Preparation parameters of the aqueous mixtures were mixture composition, the degree of hydrolysis of poly(vinyl alcohol) and borax concentration. From the rheological behavior, it could be deduced that the key factor of the interaction between hyaluronic acid and poly(vinyl alcohol) was the hydrogen bonding between them and the effect was pronounced with borax. Enhanced viscosity was observed at the composition of $20wt\%$ of hyaluronic acid solution and $80wt\%$ of poly(vinyl alcohol) and borax solution. Rheological properties were influenced by the degree of hydrolysis of poly(vinyl alcohol) and borax concentration. As the degree of hydrolysis and borax concentration increased, rheological properties increased due to the increased hydrogen bonding and networking of hyaluronate aggregates. Physical hydrogels from hyaluronic acid and poly(vinyl alcohol) were prepared and the composition dependence of the gels was rheologically investigated as well.

• Journal of Biomedical Engineering Research
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• v.23 no.4
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• pp.329-332
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• 2002

We have investigated the role of slow inhibitory neurons in spontaneous activity using a model network controlled by stochastic mean field theory based on Integrated-and-Fire excitatory and fast inhibitory neurons. It is found that inputting slow inhibitory neurons to such network induces stable spontaneous activity at a much lower threshold than without slow inhibitory neurons in the network. This threshold range is low enough to be considered as biological threshold of cortical neurons. Only slow inhibitory neurons can give adjustable negative feedback in the network keeping lower rate and lower threshold.

• Journal of Aquaculture
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• v.6 no.4
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• pp.311-321
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• 1993

Ammonia accumulation is regarded as the limiting factor of the first priority in water qualities of aquatic culture systems. Nitrification efficiency and characteristics in seawater were evaluated using Rotating Biological Contactor (RBC) process as a part of the recycling water treatment facilities for marine fish culture system. Ammonia removal efficiency regarded 99.7 to $83.7\%$ at the ammonia surface loading rates of 48 to $393 mg/m^2$ -day. RBC process was able to withstand to the fluctuation of influent ammonia concentrations and loading and produced the stable effluent. The mathematical model on the fixed-film biological reactor developed by Kornegay seemed to be suitable to RBC process kinetic evaluation for the recycling water treatment of the marine fish culture system. Area capacity constant (P) and half-velocity constant (Ks) in the model were 0.188g/m^2$-day and 1.25mg/l, respectively.

• Mycobiology
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• v.46 no.3
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• pp.177-184
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• 2018

The genus Trichoderma (Hypocreaceae, Ascomycota) consists of globally distributed fungi. Among them, T. harzianum, one of the most commonly collected Trichoderma species, had been known as a polyphyletic or aggregate species. However, a total of 19 species were determined from the polyphyletic groups of T. harzianum. Thus, we explored Korean "T. harzianum" specimens that were collected in 2013-2014. These specimens were re-examined based on a recent study with translate elongation factor 1-alpha ($EF1{\alpha}$) sequences to reveal cryptic Trichoderma species in Korea. As a result, four different species, T. afroharzianum, T. atrobruneum, T. pyramidale, and T. harzianum, were identified. Except T. harzianum, the other three species have not been reported in Korea. In this work, we describe these species and provide figures.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.139-143
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• 2001

The efficacies of several entomopathogenic nematodes of Steinernema and Heterorhabditis spp. were examined against tobacco cutworm, Spodoptera litura Fabricius. H. bacteriophora HY showed 100% mortality after 20 h against 2nd instar of tobacco cutworm. In the case of 3-4th instar, S. carpocapsae PC, H. bacteriophora HY and S. monticola CR showed 100% mortality after 47 h. In the case of 5-6th instar, S. carpocapsae PC proved more effective than the others. Generally, the number of nematodes harvested as their size decreased. Also, the highest number of nematodes was obtained in the 5-6th instar of S. litura by H. bacteriophora HY, showing about $1.3{\times}10^6$ nematodes per larva. In vitro cultured S. carpocapsae PC showed 100% mortality after 73 h against 5-6th instar tobacco cutworm, indicating that nematodes produced in vitro can be potentially used for the biological control of S. litura instead of nematodes in vivo.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.3
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• pp.187-191
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• 2003

Proteolytic enzymes existing in plant cell cultured media are the major reason for the loss of secreted human granulocyte-macrophage colony-stimulating factor (hGM-CSF). The addition of pepstatin, aprotinin and PMSF relatively decreased the proteolytic degradation of hGM-CSF in a conditioned medium, but sufficient prevention against the proteolytic activity could not be obtained with chemical protease inhibitors. Gelatin, as a competitive substrate for protease, showed a stabilizing effect in a conditioned medium. Compared to the initial hGM-CSF concentration in a conditioned medium. with 10 g/L of gelatin, 68% of the hGM-CSF remained after 5 days. In a cell culture experiment, 5 g/L of gelatin significantly stimulated the hGM-CSF production and accumulation in culture media, with no growth inhibition. compared to the controls (4.72 $\mu\textrm{g}$/L), the extracellular hGM-CSF level could be increased to 39.78 $\mu\textrm{g}$/L with the addition of 5 g/L of gelatin.