• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.5
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• pp.464-470
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• 1985

Some eels Anguilla japonica, ranging from 16 to 23 g in their weight(average: 20 g), were sampled at the private eel farming company equipped with water recycling system, located at Kimhae city, Kyungnam Province, Korea. Three kinds of vaccine were prepared with Vibrio anguillarum (EPM-8406) isolated at National Fisheries University in Korea for the immune response experiment against eels; those vaccines were made by inactivating the strain with $0.3\%$ formalin for 24 hrs at $25^{\circ}C$, heating for 3 mins or for 15 mins at $121^{\circ}C$, respectively. The various optimal vaccination conditions for the control of vibriosis in the fish were investigated based on the cultivation temperature, vaccination concentration and booster effect. The maximum titer rapidly increased with higher temperature up to $23^{\circ}C$, but there were little differences between $23^{\circ}C\;and\;28^{\circ}C$. The formalin-killed vaccine showed good efficacy at the injection concentration of above $10^8$ cells per fish and little effect at the below $10^7$ cells. The booster effect on the vaccination showed good efficacy above twice-injections with little difference between the numbers of injection.

• Journal of the Korea Concrete Institute
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• v.21 no.5
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• pp.573-580
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• 2009

This paper presents the mix composition, production method, and curing condition applied to the extruded ECC(Engineered Cementitious Composite) panel which are able to exhibit multiple cracking and potential pseudo strain-hardening behavior. In addition to the production technique of extruded ECC panel, the effect of fiber distribution characteristics, which are uniquely created by applying extrusion process, on the flexural behavior of the panel is also focussed. In order to demonstrate fiber distribution, a series of experiments and analyses, including image processing/analysis and micro-mechanical analysis, was performed. The optimum mix composition of extruded ECC panel was determined in terms of water matrix ratio, the amount of cement, ECC powder, and silica powder. It was found that flexural behavior of extruded ECC panel was highly affected by the slight difference in mix composition of ECC panel. This is mainly because the difference in mix composition results in the change of micro-mechanical properties as well as fiber distribution characteristics, represented by fiber dispersion and orientation. In terms of the average fiber orientation, the fiber distribution was found to be similar to the assumption of two dimensional random distribution, irrespective of mix composition. In contrast, the probability density function for fiber orientation was measured to be quite different depending on the mix composition.

• Journal of the Korean Electrochemical Society
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• v.6 no.4
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• pp.266-270
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• 2003

The $LiN_{0.8}Co_{0.2}O_2$ has shown outstanding electrochemical properties. The microstructure of $LiN_{0.8}Co_{0.2}O_2$ cathode was investigated by using TEM (transmission electron microscopy) and X-ray diffraction techniques. The $LiN_{0.8}Co_{0.2}O_2$ was produced by sol-gel method to synthesize fine particles less than $1{\mu}m$ in the average diameter. In this study, emphasis was given to the examination and interpretation of the microstructural change during charge-discharge cycling experiments, which appeared to be one of the main causes of early degradation of rechargeable batteries. Results showed that the $1{\mu}m$ cathode produced by sol-gel method had high reversible capacity and excellent cycling stability due to its homogeneous distribution of Ni and Co cations on u atomic scale. In particular, the $1{\mu}m$ cathode did not show severe strain induced structural defects or cubic spinel disordering during cycling experiments, which had been observed in the conventional $LiCoO_2$ cathode. The $LiNi_{0.8}Co_{0.2-x}M_x[M=Al]$ compounds show good reversibility but low discharge capacity.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.4
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• pp.177-183
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• 2016

Sewage treatment using microorganisms is affected by multiple factors such as microbial properties, characteristics of sewage and operating conditions, and nanoparticles inflow may cause negative effects on sewage treatment system especially on the system stability and efficiency. It was studied to assess the toxic effects of nanoparticles on microorganism growth. The activated sludge in the sewage treatment plant of university was cultured in the optimized medium for each strain. Bacillus (gram-positive), Pseudomonas and E.coli (gram-negative) in the activated sludge were selected as target microorganisms, and ZnO and $TiO_2$ were chosen as nanoparticles. For same concentration of nanoparticles, average growth inhibition rate of Bacillus was 60% or more, while that of Pseudomonas was less than 10%. The toxicity of nanoparticles was shown to be higher for gram-positive bacteria than gram-negative bacteria because of their differences on structure of cell wall, components of cell wall protein, physiology of cells and metabolism. ZnO affected 3 times more negative on the growth of microorganisms as compared to $TiO_2$. It was assumed that, therefore, toxicity of ZnO was found to be greater than $TiO_2$.

• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.137-145
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• 2005

Traditional screening techniques have missed up to 99% of microbial resources existing in the nature. Strategies of direct cloning of environmental DNAs comprising tine genetic blueprints of entire microbial metagenomes provide vastly more genetic information than is contained in the culturable. Therefore, one way to screening the useful gene in a variety of environments is the construction of metagenomic DNA library. In this study, the water samples were collected from Daecheong Reservoir in the mid Korea, and analyzed by T-RFLP to examine the diversity of the microbial communities. The crude DNAs were extracted by SDS-based freezing-thawing method and then further purified using an $UltraClean^{TM}kit$ (MoBio, USA). The metagenomic libraries were constructed with the DNAs partially digested with EcoRI, BamHI, and SacII in Escherichia coli DH10B using the pBACe3.6 vector. About 14.0 Mb of metagenomic libraries were obtained with average inserts 13 ${\sim}$ 15 kb in size. The genes responsible for degradation of 1, 2-dichloroethane (1, 2-DCE) via hydrolytic dehalogenation were identified from the metagenomic libraries by colony hybridization. The 1, 2-dichloroethane dehalogenase gene (dhlA) was cloned and its nucleotide sequence was analyzed. The activity of the 1, 2-DCE dehalogenase was highly expressed to the substrate. These results indicated that the dhlA gene identified from the metagenomes derived from Deacheong Reservoir might be useful to develop a potent strain for degradation of 1, 2-DCE.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1085-1091
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• 1998

The purpose of this study was to investigate the rheological properties of surimi gels and imitation crab-leg products by stress-relaxation test and to examine the correlations between stress-relaxation parameters and T.P.A. parameters. The linear viscoelasticity of surimi gels and imitation crab-leg products was observed in the range of the strain of $5{\sim}20%$ at cross-head speed 2.4 mm/sec. The average tensile forces of surimi gels and imitation crab-leg products were similar, 370.4 g and 436.4 g, respectively, but surimi gels showed higher relaxation time and viscous component (17256.1 sec, $1.357{\times}10^{10}$ poise) than those of imitation crab-leg products (6110 sec, $0.519^{\ast}10^{10}$ poise). Estimated tensile force of each exponential term in relaxation test was highly related with hardness, gumminess and chewiness of T.P.A (r=0.93, 0.93, 0.95, p<0.01), the relaxation time of each exponential term was rrelated with cohesiveness (r=0.89, p<0.01) of T.P,A. and the elastic component of exponential term with gumminess, chewiness and hardness (r=0.92, 0.94, 0.93. p<0.01) of T.P.A.. The viscous component of exponential term was related with cohesiveness (r=0.83, p<0.05) of T.P.A.. The degree of texturization was negatively related with the relaxation time and viscous component (r=-0.92, -0.96, p<0.01).

• Parasites, Hosts and Diseases
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• v.27 no.1
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• pp.47-56
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• 1989

Some biological characteristics of Centrecestus armatui were studied using albino rats as its experimental host. The metacercariae were collected from Zacco Platypus by artificial digestion method. Laboratory rats(Wistar) were fed each 100 or 200 metacercariae and sacrificed on 1, 2, 3, 4, 5, 6, 8, 14 and 28 days after infection to recover worms of various ages. The average recovery rate was 10.7% from 82 rats. The rate decreased rather slowly for the first 8 days but showed a steep decrease thereafter. Of the worms, 35.5% were recovered from the duodenum and 62.5% from the jejunum. At metacercarial stage, body length was $293{\mu\textrm{m}}$ and body width $144{\mu\textrm{m}}$. At adult stage, the length and width reached $382{\mu\textrm{m}}$ and $214{\mu\textrm{m}}$ respectively at 14 days after infection. The testes and Mehlis' gland were recognized at metacercarial stage, whereas the ovarian anlage appeared on the 1st day of infection, seminal vesicle and vitellaria on the 2nd day, and seminal receptacle and uterine eggs on the 3rd day. Until 8 days after infection the genital organs developed continuously and the number of uterine eggs increased. The above results show that albino rats are one of useful experimental hosts for C. armatus and the worms can develop to adults in 3 days after infection.

• Korean Journal of Microbiology
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• v.40 no.4
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• pp.334-341
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• 2004

Polysaccharides were prepared from Orostachys japonicus by extration with hot steam water (OJPl). The OIPl fraction was further purified by Sephadex G-50 gel filtration chromatography to produce FI (polysaccharides) and FII (oligosaccharides) fraction. The average molecular masses o fFI and FII fraction were determined to be 3050 kDa and 13 kDa, respectively. The antimicrobial activity of OIPl was tested against 8 strains of bacteria and one strain of yeast by the disc diffusion method, fluorescein diacetate (FDA) method and broth dilution method. The OIPl exhibited a very strong growth inhibition to Candida albicans. The OIPl remarkably sup­pressed the growth of Salmonella typhimurium and Staphylococcus aureus. The OIPl showed higher growth inhibition to Escherichia coli and Pseudomonas aeruginosa than propolis, positive control. When the anticancer activity of the OIPl, FI or FII was examined against human cancer cell lines and the Sarcoma 180 cells, these widely suppressed the proliferation of cell lines in the MTT assay and morphology study. Especially, they remarkably inhibited the growth of A549, HeLa and AGS cells. Also treatment of cancer cells with OJPl, FI or FII induced apoptotic cell death characterized by DNA fragmentation. The OJPl, FI or FII exhibiting various biological activities such as antimicrobial activity and anticancer activity is expected to be developed as new biohealth products.

• Journal of Life Science
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• v.8 no.4
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• pp.437-442
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• 1998

Seed and leaf size is the important morphological traits considered by plant breeder and is the important yield components in soybean. The objective of this research was to know the relationship between seed size and leaf size in 66 $F_2$ populations derived from half diallel mating system with 12 soybean strains, representing distinct seed and leaf size. The range of seed size for 12 parents used was 6.7 to 43.8 g/100 seed. Leaf width leaf length ranged 5.7 to 8.6 cm and 9.4 to 12.9 cm, respectively. Leaf width was highly correlated with leaf length with an R square of 0.754 in the $F_2$ generation. The $F_2$ regression` coefficient indicated that leaves were, on average 1.4 times greater length than in width . Leaf size (width) was highly correlated (r.0.91) with seed size (g/100 seed) in the $F_2$ generation with an R square of 0.833. Our results indicate postive correlation within seed and leaf size is common in $F_2$ segregating populations derived from crossing with soybean. The strong liner relationship we observed between leaf size and seed size in $F_2$ segragating population is useful in that in that indirect selection for a secondary character may be superior to direct selection for the primary character.

• Microbiology and Biotechnology Letters
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• v.3 no.2
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• pp.63-68
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• 1975

A biological active substance was isolated from the cultured medium of Streptomyces sp. and its biochemical characteristics were investigated. Isolation process of the substance was as follows; the pH of filterate of the cultured medium was adjusted to 3.0 with N-hydrochloric acid and saturated with sodium chloride, then chloroform was added to this filterate in one fifth portions and stirred vigorously. After extracting the active substance with chloroform in 3 stages, the chloroform layer combined and evaporatea after dehydrating with sodium sulfate. The substance was found to be to be toxic to various fresh water fishes; the lethal dose for an average size Pseudorasbora parva T. et. S. was 50ug per ml. In the acidic condition, the toxicity of the substance remained fora long time, while in the alkaline state, the toxicity was decreased very fast. This substance was found to be stable to organic solvents, but labile to heat treatment. The maximal revival time of Pseudorasbora parva T. et. S. was about 20 minutes in 25 ug/ml of the substance solution.