• International Journal of Highway Engineering
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• v.15 no.2
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• pp.105-112
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• 2013

PURPOSES : Compared to the criteria from advanced countries, Korea has conservative criteria for the buried depth of pipeline (about 30~70cm deeper) causing the waste of cost and time. Therefore, this research investigated the effect of various buried depths of pipeline on pavement performance in order to modify the criteria to be safe but economical. In addition, a recycled aggregate which is effective in economical and environmental aspect was evaluated to be used as a refilling material. METHODS : In this study, total 10 pilot sections which are composed with various combinations of pavement structure, buried depth of pipeline, and refilling material were constructed and the telecom cable was utilized as a buried pipeline. During construction, LFWD (Light Falling Weight Deflectometer) tests were conducted on each layer to measure the structural capacity of underlying layers. After the construction is completed, FWD (Falling Weight Deflectometer) tests and moving load tests were performed on top of the asphalt pavement surface. RESULTS : It was found from the LFWD and FWD test results that as the buried depth decrease, the deflections in subbase and surface layer were increased by 30% and 5~10%, respectively, but the deflection in base layer remained the same. In the moving load test, the longitudinal maximum strain was increased by 30% for 120mm of buried depth case and 5% for 100mm of buried depth case. Regarding the effect of refilling material, it was observed that the deflections in subbase and surface layer were 10% lager in recycled aggregate compared to the sand material. CONCLUSIONS : Based on the testing results, it was found that the change in buried depth and refiliing material would not significantly affect the pavement performance. However, it is noted that the final conclusion should be made based on an intensive structural analysis for the pavement under realistic conditions (i.e., repeated loading and environmental loading) along with the field test results.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.109-120
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• 2016

Flexural tests of full-scale concrete-filled U-shape hybrid composite beams were conducted. Ordinary (SS400) and high-strength (SM570) steel plates were used in the web and in the bottom flange of U-shape steel section respectively. The primary objectives were to develop the hybrid section configuration with maximized flexural capacity and to investigate its flexural strength and deformation capacity. All the hybrid test specimens in this study exhibited the plastic moment capacity and resonable deformability. It is shown that the plastic stress distribution can be assumed in calculating the flexural strength of the proposed hybrid composite beams if the plastic neural axis is located within 15% of the total beam depth from the top of the composite slab. The procedure for computing the effective flexural stiffness of hybrid composite beams is also recommended based on test results.

• Food Science of Animal Resources
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• v.28 no.2
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• pp.204-210
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• 2008

A total of 70 colonies were isolated from the Korean human milk samples on the BCP plate count agar. These LAB isolates were subcultured in 10% reconstituted skim milk, and two strain thereof were finally selected for their highest acid productions. These strains were identified as Enterococcusfaecium based on 16S rDNA sequencing data, named as Enterococcus faecium KHM-11. Sugar utilization of E. faecium KHM-11 was investigated by API 50CH kit, and 19 different sugars including D-arabinose, L-arabinose, galactose, D-glucose, D-fructose, and D-mannose were utilized. For fermentation profiles, a yogurt inoculated by E. faecium KHM-11 after 15 hour, reached at pH 4.09, titratable acidity at 1.10% and average viable counts $1.30{\times}10^9\;CFU/mL$. Effects of the administration of yogurt 0.5% of piglet diet to piglets were investigated for growth rate, analysis of blood and incidence of diarrhea. 24 heads of piglets were divided into two groups: the experimental and the control of 12 animals each. The average growth rate in the yogurt-fed group was higher for 21.67%, compared with control (p<0.05). There were no differences in the concentrations of blood glucose, cholesterol, albumin and globulin between the two treatments. Incidence of diarrhea was no in pigs fed yogurt as compare to control.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.253-258
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• 2001

A Bacillus circulans KCTC3004 $\beta$-1,3-glucanase gene contained in a recombinant plasmid pLM460 derived from subcloning the original recombinant plasmid pLM530 was trasferred into a new shuttle vector plasmid pLMS1180 by ligating linearized DNAs of pLM460 and pUB110. B. subtilis RM125 and B. megaterium ATCC14945 transformed with pLMS1180 produced the $\beta$-1,3-glucanase substantially. Most of the enzyme was produced during the exponential growth period. The maxium activities of the $\beta$-1,3-glucanase produced by the Bacillus transformants were compared with that of the B. circulans gene donor strain. The B. subtilis RM125 (pLM1180) enzyme showed the activity 14 times higher than that of the gene donor cells, followed by the B. megaterium ATCC14945 (pLMS 1180) enzyme with activity 5 times higher than that of the gene donor cells. While E. coli secreted about 7% of the produced enzyme, B. subtilis excreted the enzyme into the medium wholly and B. megaterium about 97% of the total product. The SDS-PAGE of this enzyme produced in E. coli (pLMS1180), B subtilis (pLMS1180) or B. megaterium (pLMS1180) indicated a molecular weight of 38,000. The enzymes overproduced in three different host cells hydrolyzed laminarin to produce mainly laminaribiose, laminaritriose, and laminarioligosaccharides. The plasmid pLMS1180 was stable in B. megaterium, E. coli, but was unstable in B. subtilis.

• Applied Biological Chemistry
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• v.45 no.2
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• pp.66-70
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• 2002

In this study, three kinds of Saccharomyces cerevisiae strains (KCTC 7106, 7238, 7904) were tested with respect to the ability of alcohol fermentation at $20^{\circ}C$ for 3 weeks, and S. cerevisiae KCTC 7106 was the most effective strain in alcohol fermentation with sweet persimmon. To increase the utility of sweet persimmon, the fruits stored for 1 year were used to make an alcohol beverage. It was adjusted 25% of total sugar content and allowed alcohol fermentation with shaking at 120 rpm and $30^{\circ}C$. The alcohol content of 11.6% showed at 15 days and it did not change until 25 days. The initial pH of the fermentation was near 5 then decreased to 4 within 5 days and the initial vitamin C content, 5.04 ${\mu}g/ml$, gradually decreased with fermentation periods. In the other study, the alcohol fermentation from fresh harvested persimmons showed 13% alcohol content at $20^{\circ}C$ for 30 days without agitation, while the alcohol content of the fermentation at $30^{\circ}C$ was 11.8% at 25 days and 13.4% at 35 days.

• Korean Journal of Environmental Biology
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• v.24 no.1 s.61
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• pp.38-45
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• 2006

Ecological characteristics of microbial populations inhabiting heavy metal polluted soil were investigated. The samples were collected from 293 sites around an factory and industry at Gyeoungsangbuk-do. We measured the contents of seven heavy metal elements (Cd, Cu, As, Hg, Pb, $Cr^{6+}$, CN), seven sites have been seriously contaminated by mercury and chrome. A quantitative evaluation of microbial populations in mercury and chrome contaminated soil was examined by using plate count method. Bacterial numbers in polluted soil samples ranged from $7.4X10^5\;to\;9.3X10^7\;cfu\;g^{-1}$, about $10\sim100$ fold less than the count for the unpolluted soil. Moulds were not detected in chrome polluted soil. The log values of actinomycetes of each contaminated soil samples were log ranged from 6.18 to 7.52. The ratio of actinomycetes was similar to unpolluted soil. The investigation showed actinomycetes to be the major microbial population inhabiting the mercury and chrome polluted soil. Thirty-one isolates among the total isolates were examined for antibacterial activity. These isolates were identified based on a phylogenetic analysis using 16S rRNA gene nucleotide sequences, they were categorized in three major phylogenetic groups, belong to the Streptomyces (6 strains), Saccharopolyspora (3 strains), Nocardiodes (1 strain). On the phylogenetic tree, the clade consisting of five isolates were distantly related to all of the established Streptomycetes genera, indicating the possibility as members of new species.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.63-67
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• 2012

Antibiotic resistance in animal isolates of enterococci is a public health concern, because of the risk of transmission of antibiotic-resistant strains or resistance genes to humans through the food chain. This study investigated phenotypic and genotypic resistances profile of tetracycline in 245 $Enterococcus$ isolates from bovine milk. A total of 245 enterococci were isolated from 950 milk samples. The predominant strain was $E.$ $faecalis$ (n = 199, 81.2%) and $E.$ $faecium$ (n = 25, 10.2%). $E.$ $avium$ (n = 7, 2.9%), $E.$ $durans$ (n = 6, 2.5%), $E.$ $gallinarum$ (n = 4, 1.6%), and $E.$ $raffinosus$ (n = 4, 1.6%) were also isolated. Of the 245 enterococcal isolates 76.3% (n = 187) displayed tetracycline resistance (${\geq}16{\mu}g/ml$). Of the 187 tetracycline-resistant isolates, 83.4% (n = 156), 16.1% (n = 30), and 26.7% (n = 50) possessed the genes $tet$(M), $tet$(L), $tet$(S) respectively. While 3.2% (n = 6) of the tetracycline-resistant isolates possessed all three genes $tet$(M) + $tet$(L) + $tet$(S), 8.6% (n = 16), 16.0% (n = 30), and 2.7% (n = 5) of them possessed two genes $tet$(M) + $tet$(L), $tet$(M) + $tet$(S), and $tet$(L) + $tet$(S) respectively. The tetracycline resistance pattern investigated in this study was attributable mainly to the presence of $tet$(M).

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.549-553
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• 2010

Yeast strains with good sensory properties were selected, and those yeasts were subjected to mutation to develop high glutathione producing yeasts. In addition, the antiradical activity and flavoring effect of the yeast extract were evaluated. A total of 68 strains were screened, and three strains of Saccharomyces utilis, four strains of Candida utilis, and one strain of Zygosaccharomyces rouxii were selected based on the flavoring effect. Among them, a random mutation was elicited against SEM-Y8, resulting in a high flavoring effect and growth rate. The glutathione production by SEM-Y8 increased 2.0-fold following the mutation, and the DPPH radical quenching effect of the SY8-M2-1-derived extract increased 3.2-fold compared to that of the wild type. The sensory properties of the SY8-M2-1-derived extract were better than those of garlic or onion extract in umami and mouthfulness. Thus, the SY8-M2-1 extract could be used as a functional flavoring material with improved antiradical activity.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.2
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• pp.110-117
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• 2018

In the present study, mec complex typing and SCCmec typing were performed to analyze the molecular genetic characteristics of 20 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from clinical specimens and 4 strains isolated from the ICU environments of secondary medical institutions in a Chungnam province, Korea, from June to July of 2017. Among a total of 20 MRSA strains isolated from clinical specimens, 8 cases (40%) were SCCmec type II, one case (5%) was SCCmec type IVa, and 11 cases (55%) were not-typeable in SCCmec type analysis. Among 4 MRSA isolates from the ICU environment, one strain did not have the mecA gene and 3 strains were typed as SCCmec types II, III, and IVa, respectively. Data from the present study showed that the origin of MRSA isolated from the clinical specimens was different from those from the ICU environment in most cases but the origin was concordant in one case. In this case, MRSA might be transmitted by healthcare workers to the ICU environment. Further study with a large number of cases and other hospital infection-related microorganisms will be needed. This continuous follow-up study might provide useful information on infection control in medical institutions.

• The Journal of the Korean Society for Microbiology
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• v.19 no.1
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• pp.11-24
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• 1984

Shigella remains to be an important enteric pathogen in this country for the present. Moreover, most of the isolates have become multiple resistant to various antibiotics which used to be drugs of choice for shigellosis. This study was made as an attempt to assess the present stage of antibiotic resistance and the incidence and transferability of R factors of Shigella. A total of one hundred and seventeen strains of Shigella isolated from patients in Seoul and provincial area between 1982 and 1983 were tested for their resistant to antimicrobial agents and transmission of R-plasmid. Antibiotic susceptibilities were determined by an agar dilution method. Muller hinton agar were used for the assay of drug resistance and tryptic soy broth were used for propagating medium for conjugation. Shigella isolated found to be one or more antibiotics were considered potential donor of R-plasmid. The following results were obtained. 1. Among 117 strains of Shigella isolated, 111 strains(94.9%) were found to be resistant to one or more drugs tested and 97.3% of these resistant strains were multiply resistant, indicating the multiply resistant strains were more than the single resistant strains. Only six strains were susceptible to all drugs tested. 2. Among 117 strains of Shigella isolated, 107 strains(91.5%) were resistant to Tetracyclin(Tc), 106 strains(90.6%) to Chloramphenicol(Cp) and Streptomycin(Sm), 97 strains(82.9%) to Ampicillin(Ap), 68 strains(58.1%) to Cephaloridine(Cr), 10 strains(8.5%) to Nalidixic acid(Na), 5 strains(4.3%) to Kanamycin(Km) and 2 strains(1.7%) to Rifampicin. No strain was resisfant to Amikacin(Ak) and Gentamicin(Gm). 3. All drug-resistant Shigella strains, except three, were multiply resistant to two or more drugs. Fifty eight strains were resistant to five drugs, followed by 26 strains resistant to dour drugs, 12 strains resistant to three drugs and 11 strains resistant to six drugs. 4. The 73% of multiply drug-resistant Shigella transferred their resistance to E. coli by conjugation and the resistance was considered to be mediated by R-plasmid. Resistance to Nalidixic acid and Rifampicin were not transferred by conjugation to recipient. As for the transferability of resistance to each seperate drug, Ap resistance was transferred with 73.2% frequence and Cm and Tc resistance were transferred with approximately 50-60% frequence whereas Sm and Cr resistance were transferred in 19.1-21.4% The other four drugs resistant failed to transfer their resistance to recipient. 5. As for the incidence and transferability of resistance to each seperate drug, the strains resistant to Tc and Cm were encountered most frequently with the rate of 91-92%, whereas transfer of Tc and Cm were low, 51-52%. The incidence of Sm resistance was very high(90.6%) but transferability of drugs resistance was much lower(25.4%). Though the incidence of Km reristance was much lower(4.3%) transferability of Km resistance was considerably higher(60%). 6. The greater the multiplicity of resistance, the greater was the likelihood that part of all of the resistance markers would be transferable.