• Language and Information
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• v.7 no.2
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• pp.81-101
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• 2003

This paper introduces a computerized version of the Korean Standard Pronunciation Rules that can be used in speech engineering systems such as Korean speech synthesis and recognition systems. For this purpose, we build Petri net models for each item of the Standard Pronunciation Rules, and then integrate them into the sound conversion table. The reversion of the Korean Standard Pronunciation Rules regulates the way of matching sounds into grammatically correct written characters. This paper presents not only the sound conversion table but also the character conversion table obtained by reversely converting the sound conversion table. Malting use of these tables, we have implemented a Korean character into a sound system and a Korean sound into the character conversion system, and tested them with various data sets reflecting all the items of the Standard Pronunciation Rules to verify the soundness and completeness of our tables. The test results show that the tables improve the process speed in addition to the soundness and completeness.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.185-193
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• 1987

Ten species of herbae, which have been used to treat cancers in Chinese medicine, were tested to investigate their mutagenicity or antimutagenicity in S. typhimurium TA97, TA98, TA100, TA1535, and TA1538. Scolopendra centipede was weakly active in reversion of the frameshift mutation in S. typhimurium TA97 strain and the base-pair substitution in TA100 and TA1535 strains. Other herbae such as Coix lachryma, Dianthus superbus, Tricanthoshse kirilowii, Eupatorium formosanum, Lithospermum erythrorhizon, Ansaema japonicum, Curcuma zedoaria, Helicteres angustifolia, and Euonymus sieboldianus did not show any of the mutagenic potential, regardless of the metabolic activation with rat hepatic microsomal fraction. Dianthus superbus, Eupatorium formosanum, and Euonymus sieboldianus exhibited suppressive activities on microbial mutagenesis of N-methyl-N'-nitrosoguanidine, a base-pair substitution mutagen, in TA1535 and TA100 tester strains. The antimutagenic activities of Dianthus superbus and Euonymus sieboldianus appeared to be dose-dependant.

• Elastomers and Composites
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• v.39 no.4
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• pp.263-273
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• 2004

The effects of zinc surfactant (ZB) on the bis(triethoxysilylpropyl)disulfide (TESPD)-silica mixture in natural rubber (NR) and solution butadiene-co-styrene rubber(S-SBR) were compared with respect to their rheological property, processability, physical properties, and silica dispersion. In the NR compound, addition of the ZB increased the reversion resistance time (T-2), the tensile modulus, and the BO time; however, lowered the viscosity, the HBU, and tans values. In the S-SBR copound, addition of the ZB increased the $tan{\delta}$ values while lowered the T-2, the tensile modulus the BO time, the viscosity, and the HBU of the compound. In the NR compounds, addition of the ZB significantly increased the processability and mechanical property. However, in the S-SBR compounds, it improved the processability the mechanical property was not improved.

• Korean Journal of Agricultural Science
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• v.15 no.1
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• pp.15-22
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• 1988

Factors affecting the regeneration, reversion of protoplasts from mycelium of F. velutipes were investigated and the selection of auxotrophic mutants from protoplasts of F. velutipes was performed. PDP medium stabilized with 0.6M sucrose was suitable for the regeneration of protoplasts, and regeneration frequency was 0.47-1.32. The regeneration frequency of protoplasts was increased when nutrients were added to the regeneration medium. Especially, yeast extract was the most effective to regeneration of protoplasts. Regeneration pattern of protoplasts was formation of germ tubes from bud-like cells. 13-18% of monokaryotic strains was appeared from reverted protoplasts. Five of auxotrophic mutants were isolated from strains showed survival frequency of 1.9-16.

• Korean Journal of Microbiology
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• v.50 no.2
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• pp.108-113
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• 2014

Pseudomonas aeruginosa and Vibrio vulnificus are Gram-negative human pathogens, which exert their virulence through quorum sensing (QS) regulation. The infection of these pathogens have been known to be mediated by biofilm formation in many cases and this study carried out the time-course analysis of biofilm formation depending on the QS regulation in P. aeruginosa and V. vulnificus. In P. aeruginosa, our results demonstrated that QS-deficient mutant better attached to surface at initial stage of biofilm formation, but poorly proceeded to the maturation of the biofilm structure, while wild type less attached at initial stage but developed highly structured biofilm at late stage. Because of this, the quantitative comparison of biofilm formation between wild type and the QS mutant showed the reversion; the QS mutant formed more biofilm until 10 h after inoculation than wild type, but wild type formed much more biofilm after 10 h than QS mutant. V. vulnificus has been reported to form more biofilm with the mutation on QS system. When we performed the same time-course analysis of the V. vulnificus biofilm formation, the reversion was not detected even with prolonged culture for 108 h and the QS mutant always forms more biofilm than wild type. These results indicate that the QS regulation negatively affects the attachment at early stage but positively facilitates the biofilm maturation at late stage in P. aeruginosa, while the QS regulation has a negative effect on the biofilm formation throughout the biofilm development in V. vulnificus. Based on our results, we suggest that the developmental stage of biofilm and bacterial species should be considered when the QS system is targeted for biofilm control.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1371-1377
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• 1999

Antimutagenic and antioxidative activities in the different milling fraction of rice(Oryza sativa L., illpumbyeo) were investigated. Twelve milling fractions including embryo, bran(I, II, III, IV and all) and milled rice(I, II, III, IV and V) and were obtained by abrasive milling. Antimutagenic effects of milling fraction against Trp-P-2-induced mutagenicity were shown as ${\approx}0%$ for embryo fraction, $27{\sim}86%$ for bran fractions and $64{\sim}95%$ for milled rice fractions in salmonela typhimurium reversion assay. Milled rice V, inner fraction with 80.9% milling yields, showed the highest antimutagenic activity among milling fractions Antioxidative activity, measured by peroxide value(POV) of different milling fractions was higher in embryo(28%) and bran fractions ($25{\sim}34%)$ than milled rice fractions($6{\sim}22%)$. In terms of thiobarbituric acid(TBA). embryo. bran and milled rice fractions exhibited 14, $5{\sim}21\;and \;6{\sim}20%$ antioxidative activity, respectively. Antioxidative activity, measured by electron donating ability(EDA), was 45% for embryo fraction. $35{\sim}40%$ for bran fractions and $41{\sim}65%$ for milled rice fractions. Antimutagenic activity if milling fractions was correlated with POV (r=-0.471, p<0.01) and EDA (r = 0.609, p<0.001) but not correlated with TBA. Contents of total phenolic acid and SH were higher in bran and embryo fractions than in milled rice fractions, and were reversely correlated with antimutagenic activity (r=-0.523 and -0.451. respectively, p<0.05).

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.10
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• pp.1588-1593
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• 2014

This study evaluated the genotoxic effects of 30 kGy of X-ray irradiation to four foods (chicken, egg powder, dried green onion, and black pepper). In bacterial reversion assay with Salmonella Typhimurium TA98, TA100, TA1535, and TA1537, the X-ray irradiated foods did not show a significantly increased number of revertant colonies in the presence or absence of the S9 metabolic activation system. In chromosomal aberration tests with Chinese hamster ovary (CHO) cells, the X-ray irradiated foods showed no increase in the frequency of chromosomal aberrations. In in vivo mouse micronucleus assay, the X-ray irradiated foods did not show any increase in the frequency of polychromatic erythrocytes with micronuclei. These results indicate that 30 kGy of X-ray irradiation to four foods (chicken, egg powder, dried green onion, and black pepper) showed no genotoxic effects under these experimental conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.909-915
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• 2014

This study was carried out to evaluate the genotoxicity of imported oranges irradiated with ionizing energy (0.5 and 1 kGy). In bacterial reversion assays with Salmonella Typhimurium TA98, TA100, TA1535, and TA1537, imported oranges irradiated with ionizing energy (0.5 and 1 kGy) showed no significant increase in the number of revertant colonies in both the absence and presence of the S9 metabolic activation system. In chromosomal aberration tests with Chinese hamster ovary (CHO) cells, imported oranges irradiated with ionizing energy (0.5 and 1 kGy) showed no increase in the frequency of chromosomal aberrations. In in vivo mouse micronucleus assay, imported oranges irradiated with ionizing energy (0.5 and 1 kGy) showed no increase in the frequency of polychromatic erythrocytes with micronucleus. These results indicate that imported oranges irradiated with ionizing energy (0.5 and 1 kGy) showed no genotoxic effects under these experimental conditions.

• Molecular & Cellular Toxicology
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• v.2 no.3
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• pp.176-184
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• 2006

The controversy on genotoxicity of molinate, an herbicide, has been reported in bacterial system, and in vitro and in vivo mammalian systems. To clarify the genotoxicity of molinate, we performed bacterial gene mutation test, in vitro chromosome aberration and mouse lymphoma $tk^{+/-}$ gene assay, and in vivo micronucleus assay using bone marrow cells and peripheral reticulocytes of mice. In bacterial gene mutation assay, no mutagenicity of molinate ($12-185{\mu}g/plate$) was observed in Salmonella typhimurium TA 98, 100, 1535 and 1537 both in the absence and in the presence of S-9 metabolic activation system. The clastogenicity of molinate was observed in the presence ($102.1-408.2\;{\mu}g/mL$) of metabolic activation system in mammalian cell system using Chinese hamster lung fibroblast. However, no clastogenicity was observed in the absence ($13.6-54.3\;{\mu}g/mL$) of metabolic activation system. It is suggested that the genotoxicity of molinate was derived some metabolites by metabolic activation. Molinate was also subjected to mouse lymphoma L5178Y $tk^{+/-}$ cells using microtiter cloning technique. In the absence of S-9 mixture, mutation frequencies (MFs) were revealed $1.4-1.9{\times}10^{-4}$ with no statistical significance. However, MFs in the presence of metabolic activation system revealed $3.2-3.4{\times}10^{-4}$ with statistical significance (p<0.05). In vivo micronucleus (MN) assay using mouse bone marrow cells, molinate revealed genotoxic potential in the dose ranges of 100-398 mg/kg of molinate when administered orally. Molinate also subjected to acridine orange MN assay with mouse peripheral reticulocytes. The frequency of micronucleated reticulocytes (MNRETs) induced 48 hr after i.p. injection at a single dose of 91, 182 and 363 mg/kg of molinate was dose-dependently increased as $10.2{\pm}4.7,\;14.6{\pm}3.9\;and\;28.6{\pm}6.3\;(mean{\pm}SD\;of\;MNRETs/2,000\;reticulocytes)$ with statistical significance (p<0.05), respectively. Consequently, genotoxic potential of molinate was observed in in vitro mammalian mutagenicity systems only in the presence of metabolic activation system and in vivo MN assay using both bone marrow cells and peripheral reticulocytes in the dose ranges used in this experiment. These results suggest that metabolic activation plays a critical role to express the genotoxicity of molinate in in vitro and in vivo mammalian system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2096-2109
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• 2012

This study investigates empirical issues that have received little attention in the previous research in the Korean capital market. It is to find any financial determinants on the capital structure for the firms listed in the KOSDAQ(Korea Securities Dealers Automated Quotation). Another test is performed to find any possible discriminating factors by utilizing a robust methodology, which may distinguish between the firms belonging the 'prime section' and the 'venture section' in terms of their financial aspects. Moreover, the null hypothesis that the changing trend or movement of a firm's capital structure with respect to its industry mean (or median) may be random, is also tested. For the book-value based debt ratios, size(INSIZE), growth(GROWTH), Market to book value of equity(MVBV), volatility(VOLATILITY), market value of equity (MVE) and section dummy (SECTION) showed their statistically significant effects on the book-value based leverage ratios, respectively, while size(INSIZE), growth(GROWTH), market value of equity(MVE), beta(BETA) and section dummy (SECTION) showed their statistically significant effects on the market-value based leverage ratios. This study also found an interesting result that a firm belonging to each corresponding industry has a tendency for reversion toward its mean and median leverage ratios over the five-year tested period.