• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.1
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• pp.30-34
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• 2016

In this paper, we report that selective etching on N-polar face by EC (electro-chemical)-etching effect on the reduction of bowing and strain of FS (free-standing)-GaN substrates. We applied the EC-etching to concave and convex type of FS-GaN substrates. After the EC-etching for FS-GaN, nano porous structure was formed on N-polar face of concave and convex type of FS-GaN. Consequently, the bowing in the convex type of FS-GaN substrate was decreased but the bowing in the concave type of FS-GaN substrate was increased. Furthermore, the FWHM (full width at half maximum) of (1 0 2) reflection for the convex type of FS-GaN was significantly decreased from 601 to 259 arcsec. In the case, we confirmed that the EC-etching method was very effective to reduce the bowing in the convex type of FS-GaN and the compressive stress in N-polar face of convex type of FS-GaN was fully released by Raman measurement.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.9
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• pp.1248-1252
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• 2012

Potassium added with bamboo salt showed better antioxidative effects than bamboo salt, solar salt, or purified salt. It also showed inhibitory effects on the mutagenicity of MNNG (N-methyl-N-nitro-N-nitrosoguanidine) in a Salmonella Typhimurium TA100 tester strain. At concentrations of 1.25 and 2.5 mg/plate, potassium bamboo salt and bamboo salt showed weaker co-mutagenicity effects than either purified salt or solar salt, respectively. Anticancer effects of salts were evaluated using MTT assay in HCT-116 human colon carcinoma cells. At a 1% salt concentration, the growth inhibitory rate of potassium bamboo salt was 54%, higher than that of 1 time baked bamboo salt (36%). However, purified salt and solar salt showed relatively lower inhibitory effects of 19% and 23%, respectively. To determine the inhibitory mechanisms of potassium bamboo salt, the expression levels of Bax and Bcl-2 genes in HCT-116 cells were determined by RT-PCR. Potassium bamboo salt significantly increased Bax and decreased Bcl-2 expression levels unlike bamboo salt, purified salt, and solar salt (p<0.05). Therefore, addition of potassium to salt decreased co-mutagenicity and increased in vitro antioxidative and anticancer effects.

• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.66-69
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• 2012

Five strains out of 200 candidate strains (SG 1-9, 1-12, SG 2-8, 2-10, and 2-17) were selected to determine their antifungal activity against Raffaelea quercus-mongolicae. The 16S rDNA sequences of the five strains were determined by sequencing analysis and analyzed by the homology of the blast program at NCBI. The homology search showed that SG 1-9 and 1-12 had a 98% homology with Streptomyces cinnamoneus and 98% homology with Burkholderia cepacia, while SG 2-8, 2-10, and 2-17 had a 99% homology with Streptomyces fradiae, a 97% homology with Staphylococcus epidermidis, and a 99% homology with Staphylococcus epidermidis. Out of the five selected strains, organic extract and protein extracts of SG2-17 strain broth were employed to determine antifungal activity against Raffaelea quercus-mongolicae. The organic extract exhibited antifungal activity, but the protein extracts did not demonstrate such an activity. Three organic solvents, butanol, benzene, and ethyl acetate, were also used for determination of antifungal activities. The activity measurements revealed that benzene extract possessed the greatest inhibitory effect on the growth of Raffaelea quercus-mongolicae, with the next highest being butanol extract, and ethyl acetate extract being the lowest.

• Microbiology and Biotechnology Letters
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• v.38 no.2
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• pp.198-206
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• 2010

The aim of this work was to investigate the synergically bactericidal effects and cellular responses of tea polyphenols (TPP) and imipenem on imipenem-resistant Pseudomonas aeruginosa. Imipenem-resistant Ps. aeruginosa was isolated from patient in hospital. The bactericidal effects of TPP and imipenem were evaluated on the basis of its minimum inhibitory concentrations (MIC). The combined use of TPP and imipenem resulted in 16-fold and 8-fold reductions in the MICs of imipenem for the imipenem-susceptible and imipenem-resistant Ps. aeruginosa, respectively. The bactericidal effects of the imipenem and TPP against the Ps. aeruginosa was evaluated using the time-kill assay. The synergetic effects of the combinations of TPP and imipenem against Ps. aeruginosa were confirmed. Western blot using anti-DnaK and anti-GroEL monoclonal antibodies was performed to investigate the expression of stress shock proteins (SSPs) in imipenem-susceptible and imipenem-resistant strains exposed to TPP. The amount of SSPs were induced as the exposure time increased and decreased. The molecular weights of DnaK and GroEL were 70 kDa and 60 kDa, respectively. SDS-PAGE with silver staining revealed that the amount of lipopolysaccharides (LPS) increased or decreased in the strain treated to different concentrations and exposing periods of TPP. Scanning electron microscopic analysis demonstrated the presence of umblicated and wrinkled surfaces for cells treated with TPP or imipenem.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.179-185
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• 2005

Polycyclic aromatic hydrocarbons (PAHs) are a kind of toxic environmental pollutants and has been accumulated usually in marine sediments. Due to their potential hazardous to human, removal of PAHs from environments has been great concern. In the present study, the effect of microbial inoculation and the supplementation of mixed form cyclodextrin (M-CD) was assessed in the pre-sterilized or nonsterilized microcosms for optimizing operational conditions for ex situ bioremediation of sediments contaminated by PAHs. Activity of electron transport system (ETSA) was increased by the addition of M-CD regardless of inoculation of microorganisms in microcosms without sterilization. The degradation rate of PAHs in sterilized microcosms was app. 9-20% by the inoculation of single strain and 24-37% by the inoculation of microbial consortium supplemented with 1% M-CD, respectively. The degradation was not observed in microcosms without sterilization under the same conditions. The proportion of inoculated microorganisms also decreased in nonsterilized microcosms. Signals of inoculated bacteria were decreased to detection limit after 2 days in the microcosms without M-CD. In conclusion, microbial inoculation with appropriate carbon sources and removal of natural flora and grazers are required for the efficient ex situ bioremediation of sediments contaminated by PAHs in bioslurry reactor.

• Journal of Dairy Science and Biotechnology
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• v.32 no.2
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• pp.147-156
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• 2014

The aim of this study was to investigate the physiological characteristics and anti-obesity effects of E. faecalis MD366 isolated from raw milk. E. faecalis MD366 inhibited lipase activity ($65.0{\pm}0.9%$) and differentiation of 3T3-L1 adipocytes ($27.4{\pm}1.4%$) at a concentration of $100{\mu}g/mL$ ($10^8CFU/g$ E. faecalis MD366). The optimum growth temperature of E. faecalis MD366 was $37^{\circ}C$. Among 16 tested antibiotics, E. faecalis MD366 demonstrated the highest sensitivity to novobiocin and the highest resistance to neomycin, kanamycin, and vancomycin. The strain also showed high acid phosphatase activity. Moreover, E. faecalis was relatively tolerant to bile juice and acid, and displayed high resistance to Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus (80.4%, 60.2%, and 65.4%, respectively). These results demonstrate that E. faecalis MD366 can be potentially used as a probiotic with anti-obesity effects.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.206-211
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• 1996

It was generally known that over-ingestion of dietary orotic acid caused hepatic disorder by the lesion of fatty acid and cholesterol synthesis in rats. The present study was carried out to investigate the effects of dietary orotic acid on the lipid composition of serum, liver and kidney of rats. For the experiments, rats were fed with commercialized chow powder diet in the presence or absence of 1% orotic acid. The prepared diets were fed to male rats (Sprague-Dawley strain, $90{\sim}100$ g of body weight for 21 days. According to the results, orotic acid treated group showed that each concentration of serum cholesterol, triglyceride and phospholipid was significantly decreased (p<0.05). The centration of liver triglyceride was significantly decreased (p<0.05). In the presence of 1% orotic acid, the weight of liver inclosed while that of kidney decreased. The treatment of orotic acid seemed to have no effects on the phospholipid composition in liver and kidney, except the kidney lysophosphatidylcholine. In the comparison of the phospholipid composition between liver and kidney, the levels of sphingomyeline and phosphtidylethanolamine in the kidney were higher than those in the liver. Among the composition of fatty acid in kidney, the concentration of linoleic acid (18 : 2) was increased, and the concentration of arachidonic acid (20 : 4) was decreased with the addition of the orotic acid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.436-444
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• 2013

This article presents the dynamic response of nano-scale plates using the nonlocal continuum theory and higher-order shear deformation theory. The nonlocal elasticity of Eringen has ability to capture the small scale effects and the higher-order shear deformation theory has ability to capture the quadratic variation of shear strain and consequently shear stress through the plate thickness. The solutions of transient dynamic analysis of nano-scale plate are presented using these theories to illustrate the effect of nonlocal theory on dynamic response of the nano-scale plates. The relations between nonlocal and local theories are discussed by numerical results. Also, the effects of nonlocal parameters, aspect ratio, side-to-thickness ratio, size of nano-scale plate and time step on dynamic response are investigated and discussed. The amplitude and cycle increase when nonlocal parameter increase. In order to validate the present solutions, the reference solutions are used and discussed. The theoretical development as well as numerical solutions presented herein should serve as reference for nonlocal theories as applied to the transient dynamic analysis of nano-scale structures.

• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.101-106
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• 2003

In order to study the optimum daily protein allowance for broiler breeders of 24 to 64 weeks of age on a control-fed basis, an experiment was carried out with 400 hens of Arbor Acres strain. Four levels of protein allowances were used to supply 18 to 24g of protein per day in 2g increments. As the age of hens increased, a same stepwise increase and decrease in daily energy allotment was used in all treatments. Same amount of calcium, phosphorus, methionine and lysine were supplied in all treatments and throughout laying period. Hen-day egg production was highest in hens receiving 20g protein per day(p<0.05), but there was no significant difference among those fed daily protein ranging 18 to 22g, and increasing the daily protein allotment up to 24g resulted in a significant decrease(p<0.05). Average egg weight showed a trend to increase as the daily protein allowance increase(p<0.05), but no significant difference was found among the hens fed daily protein 20 to 24g. Feed and ME conversion was superior in hens receiving 20g daily protein(p<0.05). CP conversion was increased as the daily protein allowance increase(p<0.05), but there was no significant difference between hens receiving 18 and 20g daily protein. Feed cost required per egg or per kg egg was lowest in hens fed 20g daily protein. It could be concluded that the optimum daily protein allowance was 20g in all performances.

• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.107-112
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• 2003

This experiment was conducted to study the optimum energy feeding system for broiler breeders peaked in summer season with 400 caged hens of Ross strain. Four of energy supply series which were different in daily energy allotment during laying period were employed for 40 weeks from 24 to 64 weeks of age. All experimental diets were formulated to contain 2,750 kcal ME/kg with adjustments made in total feed allotment to provide the desired energy levels. Total consumption of the feed would provide 20 grams of protein, 4 grams of calcium and 0.35 grams of available phosphorus. There were no significant difference in hen-day egg production and average egg weight among the series of energy supply, but egg production showed a trend to decline as the level of energy allotment increased. Feed, ME and CP conversion and feed cost required per egg or per kg egg were significantly increased as the level of energy allotment increased(p<0.05). It was concluded that the Treatment 1, which supplied 280kcal ME per day at the age of 24 weeks and then increased the energy supply up to 400kcal ME per day at the peak period of 30∼34 weeks of age, was superior in all production parameters.