• Journal of Microbiology and Biotechnology
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• 제27권7호
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• pp.1331-1335
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• 2017

In this study, the feasibility of introducing calcite-forming bacteria into concrete pavements to improve their mechanical performance was investigated. Lysinibacillus sphaericus WJ-8, which was isolated in a previous study and is capable of exhibiting high urease activity and calcite production, was used. When analyzed via scanning electron microscopy (SEM) and X-ray diffraction, WJ-8 showed a significant amount of calcite precipitation. The compressive strength of cement mortar mixed with WJ-8 cells and nutrient medium (urea with calcium lactate) increased by 10% compared with that of the controls. Energy dispersive x-ray spectroscopy analyses confirmed that the increase in strength was due to the calcite formed by the WJ-8 cells.

• 약학회지
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• 제28권4호
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• pp.223-229
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• 1984

Microcapsules of indomethacin were prepared by the complex coacervation technique using gelatin-gum arabic as the wall-forming material. The effects of varying drug-to-matrix ratios and formalization time, and hydroxy propyl cellulose (HPC) added on the release of drug from microcapsules were studied. As the amount of wall-forming material increased, the drug content in the microcapsules decreased and the release of drug from microcapsules was retarded. The drug content was lower in the HPC added microcapsules than that in the microcapsules was retarded. The drug content was lower in the HPC added microcapsules than that in the microcapsules without HPC and the microcapsules with 1:4 drug-to-matrix ratio showed the slowest release. The release rate of the drug from microcapsules with 1:2 drug-to-matrix was delayed according to the increase of formalization time and the microcapsules formalized for 24hr showed ratio the most retardation.

• 한국세라믹학회지
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• 제37권4호
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• pp.332-337
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• 2000

Forming mechanism of fibrous TiC during self-propagating high temperature synthetic reaction was analyzed and suggested. It was revealed that critical temperature for the stable fiber formation was not the melting point of TiC, but the eutectic reaction temperature of TiC and C. Minimum amount of TiC diluent addition required to form fibers was calculated to be 25.6%, which was consistent with the experimental result. Synthesized fibers were found hollow tube-like. The morphology was explained by the diffusion rates of C and Ti in TiC, and by the molar volume chnage of C during the reaction. Expanding shell model was suggested for the hollow fiber formation mechanism.

• 미생물학회지
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• 제24권2호
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• pp.98-105
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• 1986

Rhizobium melitoli 102F51에 N-methyl-N'-nitro-N-nitrosoguanidine 및 UV를 처리하여 heme 합성 특성이 다른 세 그룹의 mutant 즉 백색, 적백색 및 적색근류형성 mutant를 선별하여 이들 중 mutant들의 acetylene 환원력, 및 ${\delta}-aminolevulinic$ acid dehydratase (ALAD)를 free living 및 bacteriod 상태하에서 서로 비교하였다. 백색 근류를 형성하는 mutant는 적색 근류형성 mutant에 비하여 acetylene 환원력이 훨씬 낮았으며 ALAS 및 ALAD 활성은 free-living 상태에서는 각 mutant group 사이에서 큰 차이를 보이지 않았으나 bacteriod 상태에서는 백색근류생성 mutant에서 적색 근류형성 mutant group에 비하여 ALAS 및 ALAD 공히 현저히 낮았다. 근류에서 ALAS 활성은 heme 합성양에 비례하여 급진적으로 증가하였으나 ALAD 활성은 plant fraction에서는 감소하는 반면 bacteroid fraction에서는 완만하게 증가하였다.

• Journal of Nutrition and Health
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• 제26권1호
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• pp.3-12
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• 1993

This study was performed to investigate effects of dietary fat content and degree of saturation on the function of the immune system. Sixty male BALB/c mice average-weighing 17g were divided into three dietary groups: 5% safflower oil group, 20% safflower oil group, 19.3% beef tallow & 0.7% safflower oil group. Food intake and body weight were measured every day. At 4th, 7th, 10th week after dietary treatment, organ weight measurements, delayed-type hypersensitivity test, plaque forming cell test, agglutination test, differential white cell count and histological examination of spleen were performed. Results are follows; 1) Body weight, food intake and calorie intake were not different in the three dietary groups during the experimental period($\alpha$=0.05). 2) Liver weight was significantly higher in 5% safflower oil group($\alpha$=0.05). Spleen index was slightly higher in mice fed 5% safflower oil and 19.3% beef tallow & 0.7% safflower oil. Thymus index in all mice was decreased by aging. 3) Delayed-type hypersensitivity of the mice fed 5% safflower oil and 19.3% beef tallow & 0.7% safflower oil was significantly higher than that of the mice fed 20% safflower oil. 4) The number of plaque forming cell was significantly reduced at 10th week compared to 7th week in all group($\alpha$=0.05). Although there was no difference in plaque forming cell among three groups at 10th week, 5% safflower oil group showed slightly higher plaque forming cell than 20% safflower oil group at 7th week. 5) At 4th week, agglutination test seems to be higher in 5% safflower oil group and 19.3% beef tallow & 0.7% safflower oil group compared to 20% safflower oil group. 6) Percentage of neutrophil and eosinophil was slightly reduced in 20% safflower oil group. 7) Spleen tissue was not affected by and dietary treatments. According to our results, the higher the fat content & unsaturation of the diet the lower the cell-mediated immunity of the mice. Humoral-immunity did not appear to be affected by the dietary manipulation. However humoral-immunity was decreased significantly by aging in all dietary groups.

• 한국치위생학회지
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• 제17권1호
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• pp.13-25
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• 2017

Objectives: The purpose of this study was to compare colony forming unit (CFU) method and multiplex real-time polymerase chain reaction (MRT-PCR) method for accurate quantitative analysis of bacteria. Methods: We compared the CFU method and the MRT-PCR method, which are still used in Korea, for Prevotella intermedius (P. intermedius), a periodontal disease pathogen selected by MRT-PCR, and Streptococcus mutans (S. mutans), a dental caries causative organism. The subjects of this study were 30 patients who visited the C dental hospital. Results: Total microorganisms in MRT-PCR method were significantly higher in both types of bacteria (p<0.05), since DNA of dead bacteria was also analyzed. This was because the periodontal dise(-) anaerobes, and even dead bacteria contain large amounts of toxic substances called LPS in the extracellular membrane, and fimbriae and pili, which are motility structures, still remain as a strong toxic substance in periodontal tissue. Conclusions: Therefore, in terms of the total amount of bacteria found, the MRT-PCR method will be a useful technique for searching all the bacteria in the oral cavity including live bacteria, as well as sterilization.

• Design & Manufacturing
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• 제13권4호
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• pp.23-27
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• 2019

People's interest in the environmental problems of the Earth is growing as they come to the modern world, and research is being actively conducted on how to protect the environment. As a result, the automobile industry, one of the causes of environmental pollution, is also affected. Therefore, research is being conducted to improve the fuel economy and light weight of cars, development of pollution-free cars such as electric cars, and aluminium materials that are lighter than ordinary steel sheets and easier to recycle are gaining attention. In this experiment, the material was formed to form a form of aluminium and the material reduction rate of the side wall of the foam was tested according to the amount of side wall. The material used in the experiment was A3003-O, which is less plastic than normal steel plates, but has excellent corrosion resistance, plasticity and weldability compared to aluminium materials, but has poor tensile strength. For tensile testing, a certain array of Forming Shapes was molded and the height of the Forming was set to 5mm, and the height of the Forming was 4.7mm, indicating that the difference between the first 5mm Forming and the height was not large. In addition, the material reduction rate was tested by giving 15, 0, and -0.15 teas, respectively, and was found to be valuable as a product only for -0.15.

• 한국세라믹학회지
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• 제46권1호
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• pp.53-57
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• 2009

The h-BN powder was synthesized by amorphous $B_2O_3$ and activated carbon at $1550^{\circ}C$ in nitrogen atmosphere, whose properties were examined according to $MgB_6$ addition. Amount of $MgB_6$ addition was varied in the range of $0{\sim}$10\;wt% of the initial mixture. It was observed that $MgB_6$ addition led to an increase in the amount and the grain size of h-BN and decrease in the amount of $B_4C$ forming. When $MgB_6$ added 5 wt%, the amount and crystallinity of h-BN increased as the holding time at the synthesis temperature was prolonged. It was also confirmed that the regularity of three-dimensional ordering of h-BN increases.

• 한국세라믹학회지
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• 제44권6호
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• pp.331-337
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• 2007

High temperature reaction behaviors of various oxide materials (such as bauxite, pyrophyllite, mullite and fused silica powders) used in the refractory materials for tap-hole plugging of blast furnace were investigated with varying temperature in the carbon surrounding. Kinetics of carbothermal reduction of $SiO_2$ for forming SiC with high corrosion resistance were strongly dependent on it's crystalline phase. SiC generation yield increased with increasing catalyst amount in oxide regardless of generated SiO gas amount at temperature of $<1500^{\circ}C$. However, in case of fused silica over $1500^{\circ}C$, SiC generation yield was dominantly influenced by SiO amount without catalyst effect. Bauxite showed the most effective carbothermal reduction reaction, since bauxite have a large amount of catalyst and well-dispersed $SiO_2$ phase in oxide matrix.

• 한국세라믹학회지
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• 제12권2호
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• pp.3-9
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• 1975

The continuous grading method of pyrophyllite particles was adopted to prepare the refractories for ladle. The optimum conditions of fabrication adjusting the binders, the amount of water, the forming pressure and the firing temperature were investigated. The various properties, such as strength, density, porosity, thermal shock, corrosion resistance to slag were measured and compared with properties of ladle bricks presently used at local steel plants. The specimen studied in the present investigation showed a rather superior properties to theconventional product available locally.