• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.141-148
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• 2016

This paper employed finite element method (FEM) to study the dynamic response of Steel Fiber-Reinforced Concrete(SFRC) panels subjected to impact loading by spherical projectiles. The material properties and non-linear stress-strain curves of SFRC were obtained by compression test and flexural test. Various parametric studies, such as the effect of fiber volume fraction and thickness of panels, are made and numerical analyses are compared with experiments conducted. It is shown that protective performance of concrete panels will be improved by adding steel fiber. Area loss rates and weight loss rates are decreased with increasing fiber volume fraction. Also, penetration modes can be expected by FEM, showing well agreement with experiment. Results can be applied for designing the protection of military structures and other facilities against high-velocity projectiles.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.461-471
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• 1989

For the mixed-mode crack problems the direction of crack growth, the crack path and the rational representation of fatigue crack growth rates should be studied to predict fatigue life and safety of structures. In this study, a round specimen which produce nearly identical effects in all loading directions is proposed to make an easy measurement of initial direction of crack growth. The mode I and mode II stress intensity factors of the specimen were calculated using finite element method, in which the square root singular stresses at the crack tip are modeled by means of four rectangular quarter-point eight-noded elements surrounding the crack tip. Experimental results for high strength aluminum alloy showed that the direction of mixed-mode crack growth agree well with maximum principal stress criterion as well as minimum strain energy density criterion, but not with maximum shear stress criterion. From data of fatigue crack growth rates using crack geometry projected on the line perpendicular to the loading direction it is easily established that mixed-mode fatigue crack growth in 5083-H115 aluminum alloy goes predominantly with mode I crack growth behaviors.

• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.70-77
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• 2007

Pseudomonas sp. KM1 was separated from soil contaminated by petroleum and identified. The isolated strain is Gram-positive, rod-shaped and immotile. In batch culture, the optimum cultivation temperature and pH was $35^{\circ}C$ and 7, respectively. Biodegradation of PAHs experiment with soil slurry system was performed using Pseudomonas sp. KM1. Pseudomonas sp. KM1 could degrade 7 PAHs including naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, pyrene, and fluoranthene. These mixed PAHs was easily degraded within one day except fluoranthene, which was degraded much slowly, taking several days by this isolated bacteria. Pseudomonas sp. KM1 is good candidate for bioremediation of PAHs contaminated soils. Biodegradation rates of naphthalene, phenanthrene and pyrene in soils were different at each soil, and the rates were decreased as sorption capacity increased.

• Korean Journal of Crystallography
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• v.3 no.2
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• pp.120-128
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• 1992

Single crysals of BaTiO3 were grown by TSSG technique at various cooling rates. Morpolo girts, defects and domain structures of the grown crystals were investigated. At the cooling rates below 0.5℃/hr, equant single crystals were obtained and the 11111 faces were dominantly developed. If the cooling rate was much faster or if the vortical temperature gradient in the so lotion was very large, the solution became unstable and the needle formed BasTil04 o crystals were precipitated. Two sets of parallel lamella domains are arranged perpendicular to each other and the irregularly shaped boundaries are fixed between them. These sets of domains show remarkable orientation contrast in x-ray topography. Heating the crystal above 127℃, the phase transition from tetragonal to cubic occurs. The phase transition front (PTF) moves in the direction of temperature gradient. Domains in the tetragonal phase are successively rearranged and regular strain patterns appear in the cubic phase. The habit plane of PTF in BaTi03 is found to deviate from a l1101 lattice plane by app roximately 9°.

• Journal of Food Hygiene and Safety
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• v.35 no.6
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• pp.602-606
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• 2020

This study was designed to investigate the dynamic behaviors of phages against Salmonella enterica subsp. enterica serovar Typhimurium ATCC 19585 (STWT), S. Typhimurium KCCM 40253 (STKCCM), ciprofloxacin-induced S. Typhimurium ATCC 19585 strains (STCIP), and S. Typhimurium CCARM 8009 (STCCARM). Phages, including PBST-10, PBST-13, PBST-32, PBST-35, P-22, and P-22 B1 had narrow host ranges. The adsorption rates of all phages ranged from 47 to 85%, 58 to 95%, and 61 to 93%, respectively, against STWT, STKCCM, and STCIP, while the lowest adsorption rates ranged from 14 to 36% against STCCARM. The phage burst sizes were from 43 to 350, 37 to 530, 66 to 500, and 24 to 500 plaque-forming units (PFUs) per infected STWT, STKCCM, STCIP, and STCCARM, respectively. The STCIP strain was effectively inhibited by all phages at the early of incubation period. These results provide useful information for better understanding the phage behaviors against antibiotic-resistant and antibiotic-sensitive pathogens.

• ALGAE
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• v.32 no.1
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• pp.57-66
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• 2017

The red alga Gracilaria vermiculophylla, a species native to the waters of Korea and Japan, has invaded marine coastal areas of Europe and the Americas, thriving in conditions that differ from those of its native habitat. In recent years, G. vermiculophylla has been discovered in the Long Island Sound (LIS) estuary growing alongside the native congener Gracilaria tikvahiae. The goal of this study was to determine whether the two strains of G. vermiculophylla from different regions of the world have evolved genetic differences (i.e., ecotypic differentiation) or if the physiological performance of the strains simply reflects phenotypic plasticity. Two strains of G. vermiculophylla (isolated in Korea and LIS) and a strain of the LIS native G. tikvahiae were grown for four weeks under temperatures ranging from 20 to $34^{\circ}C$ using a temperature gradient table (all other environmental conditions were kept constant). At the end of each week, wet weight of each sample was recorded, and thalli were reduced to the original stocking density of $1gL^{-1}$ (excess biomass was preserved for tissue carbon and nitrogen analysis). Generally, the growth rates of Korean G. vermiculophylla > LIS G. vermiculophylla > G. tikvahiae. After one week of growth G. tikvahiae grew 9.1, 12.0, 9.4, and 0.2% $d^{-1}$, at temperatures of 20, 24, 29, and $34^{\circ}C$, respectively, while G. vermiculophylla (LIS) grew 6.6, 6.2, 5.7, and 3.6% $d^{-1}$. G. vermiculophylla (Korea) grew 15.4, 22.9, 23.2, and 10.1% $d^{-1}$, much higher than the two strains currently inhabiting the LIS. On average, the LIS G. vermiculophylla strain contained 4-5% DW N, while the Korean strain and G. tikvahiae had more modest levels of 2-3% N DW. However, tissue N content declined as temperature increased in LIS and Korean G. vermiculophylla. The non-native haplotype may have evolved genetic differences resulting in lower growth capacity while concentrating significantly more nitrogen, giving the non-native a competitive advantage.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.9
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• pp.1236-1243
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• 2010

The aim of this study was to screen lactic acid bacteria for the fermentation of garlic and to assess the increase in inhibitory activity of garlic fermented against antibiotic-resistant pathogens for use as an animal feed supplement. We screened 45 strains of lactobacillus for the fermentation of garlic. Of these strains, 23 showed similar growth rates with or without allicin. Cultures of the 23 strains were mixed with an equivalent amount of garlic juice and incubated overnight at $37^{\circ}C$. The three strains with the lowest pH values were Lactobacillus paracasei KCTC 3169, L5 strain, and L. reuteri SW. Garlic juice fermented by the L5 strain more strongly inhibited antibiotic-resistant pathogenic bacteria than L. paracasei KCTC 3169, L. reuteri SW, or garlic juice itself. By examining carbohydrate utilization, morphologic properties and 16S rRNA gene sequences, we identified the L5 strain as Pediococcus pentosaceus and deposited it in the name of P. pentosaceus KACC 91419 into the Korea Agricultural Culture Collection. To identify the antimicrobial compound from the garlic filtrate fermented by P. pentosaceus KACC 91419, we fractionated P. pentosaceus KACC 91419 culture on a C18 column and checked the antimicrobial activity of fractions A6 to A10. Only fraction A9 showed inhibitory activity on Staphylococcus aureus. Comparing the mass spectra of the fractions with and without antimicrobial activity, we observed a single dominant product ion (m/z 157.99) from the fraction showing antimicrobial activity. Its molecular mass (157.99) was 2 atomic mass units less than that of allicin (162.02). This suggests that allicin might be converted to its derivative, which has antimicrobial activity, during fermentation by P. pentosaceus KACC 91419.

• Journal of Mushroom
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• v.10 no.1
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• pp.37-43
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• 2012

This study was carried to identify a correct species and asses genetic diversity within the same species of Polyporus spp. preserved in Division of applied Microbiology. Contaminated isolates showed different growth rates, morphology and color of hyphae. We have reconstructed the phylogenetic tree of a select group of Polyporus spp. using nucleotide sequences of the internal transcribed spacer region(ITS) region. The phylogenetic tree was constructed by using the neighbor-joining method. PELF primers of 20-mer were used to assess genetic diversity of preserved isolates. Sequence analysis showed that three strains were different species and four strains were identified completely different nomenclature. According to the analysis of ITS sequences, the genus Polyporus clustered into five distinct group, most of which correlated with species-groups identified by RAPD method. Four isolates included strain PM02 showed high similarity with P. arcularius, four isolates included strain PM03 high similarity with P. alveolaris, three isolates included strain PM01 high similarity with P. tuberaster, and PM 06 and PM04 high similarity with P. brumalis and P. squamossus. Isolates were collected in the United States(PM10, PM11) was identified as P. alveolarius and P. arcularius. RAPD analysis of genetic polymorphisms of genus Polyporus showed a very different band patterns. As the result of RAPD and ITS region sequences analysis for preserved isolates, it seems likely that 6 isolates of Polyporus spp. may be need to reclassify or eliminate from preserved catalogue.

• Parasites, Hosts and Diseases
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• v.31 no.4
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• pp.363-370
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• 1993

This study was performed to evaluate the prophylactic effects of trimethoprim- sulfamethoxazole (TMP-SMZ) In mice experimentally infected with virulent RH strain and avirulent Beverley strain of T dognii. The mice infected with $1{\times}10^5$ tachyzoltes were used In the measurement of mean survival days, and the mice infected with 10 cysts were used In the tltratlons of specific antibodies and enumeration of brawn cysts. Mean survival days of mice were significantly increased In mice treated with TMP-SMZ as compared with splramycln-treated and untreated control group. Mean survival days and survival rates of mice were Increased according to the Increment of dosages, and TMP-SMZ protected 100% of mice after fifteen daily dose of 24 mg/mouse or more admlnlsted orally. Toxoplasma-specific serum IgG and IgM antibody titers were slgnlflcantly lower in mice treated with TMP-SMZ than those of splramycln-treated and untreated control group. Toxoplosma cysts were not found In mice treated with TMP-SMZ at a dose of 24 mg/mouse or more per day but the group of splramycin treatment and untreated controls were found in the brain from 20 days after Infection. The present results revealed that TMP-SMZ can be used as a prophylactic agent against murine toxoplasmosls after Intraperitoneally challenges with the virulent or avlrulent strain of T. gondii.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.7
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• pp.1027-1032
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• 2008

A study was conducted to evaluate the effects of dietary yeast derived ${\beta}$-glucan and single-strain probiotics on the growth performance and antibody response in broiler chicks. Six hundred and thirty 1-d-old male broiler chicks were divided into seven groups, placed into three pens per group (30 birds per pen) and fed one of seven non-medicated corn-SBM based experimental diets containing 0.025, 0.05 or 0.1% Saccharomyces cerevisiae ${\beta}$-glucan and 0.05, 0.1 or 0.2% Bacillus amyloliquefaciens (BA-pro, $1.3{\times}10^9/g$) or devoid of them for 5 wk. The body weight gains in groups fed diets containing 0.025 or 0.1% ${\beta}$-glucan, 0.1% or 0.2% BA-pro were significantly higher (p<0.05) than the control over 1-35 d. Feed conversion rates of groups fed ${\beta}$-glucan and BA-pro tended to be improved compared to the control group. There were no significant differences in the relative weights of liver, abdominal fat and breast muscle. No significant differences were observed in the activities of serum enzymes and concentrations of various cholesterol fractions. The antibody titers against Newcastle disease or infectious bronchitis virus in the chicks fed diets containing ${\beta}$-glucan and BA-pro were significantly higher (p<0.05) than in the control. The concentrations of cecal lactic acid bacteria in all groups fed BA-pro were significantly increased (p<0.05) compared to the control. These results indicated that dietary yeast derived ${\beta}$-glucan and BA-pro exerted growth-promoting and immune-enhancing effects in broiler chickens. In addition, BA-pro added to the diets modulated the profiles of cecal microflora, reflecting a potential to be beneficial microorganisms in chickens.