• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.448-456
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• 2010

The mechanical behavior of granular soils is affected by particle bonding including natural cementation. This study addresses a simple model of small strain stiffness and salt concentration based on wave measurements of salt-cemented particulate media. Published models of artificially cemented soils with different curing methods and several types of cementation agents are reviewed. Glass beads with the median diameter of D50 = 0.5mm are prepared in rectangular cells using the water-pluviated method in salt water with different concentrations. Piezo disk elements and bender elements embedded in the cell are used for the measurements of compressional and shear waves. The relationships between elastic wave velocities and salt concentration show an exponential function. The measured small strain stiffness matches well the predicted small strain stiffness based on micromechanics for simple cubic monosized sphere particles. This study demonstrates that the salt concentration in salt-cemented specimen may be evaluated by using elastic wave velocities.

• 생명과학회지
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• 제18권7호
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• pp.947-951
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• 2008

아연은 많은 생리학적인 기능을 가지는 필수미량 원소로, 특히 성기능에 있어서 중요한 역할을 하는 것으로 잘 알려져 있다. 열대 과일 Rambutan으로부터 분리된 아연 고함유 효모의 미네랄 성분은 아연 306 ppm, K 28,640 ppm, Mg 2,342, Na 1,048 ppm, Ca 366 ppm, Fe 236 ppm 및 Mn 4 ppm이 함유되어 있었다. 혈청 중 성호르몬인 테스토스테론(testosterone) 농도는 정상군에 비해 에탄올 급여 실험군에서 감소 경향을 나타내었다. 에탄올 급여에 의한 성호르몬 테스토스테론의 농도 감소는 아연 고함유 효모 투여로 현저하게 증가하였다. 또한, 혈청 중 아연 함량에 에탄올 급여 실험군에서 감소경향을 보였고, 이러한 감소는 아연 고함유 효모 투여로 현저하게 증가하였다. 따라서, 에탄올 투여에 의한 혈중 아연 및 테스토스테론 농도의 감소효과는 아연 고함유 효모 투여로 상쇄되는 것으로 나타나 본 실험에 사용된 아연 고함유 효모는 성기능 관련 건강기능식품의 소재로서 산업적으로 유용하게 사용될 것으로 사료되어 진다.

• 한국환경보건학회지
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• 제23권1호
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• pp.18-27
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• 1997

The isolation, morphological study and growth characteristics of the algae were investigated from Lake Chuam. The isolated algae were applied the Agal Growth Potential test. The method of isolation and purification of the algae were used to Agar plating(AP), nutrient enrichment(NE), dilution(DI) and micro capillary technique(MC). Total isolated algae were 21 species. They were composed of Cyanophyceae, Dinophyceae, Bacillariophyceae, Euglenophyceae and Chlorophyceae. The numbers of algal strain by isolation technique were highest in dilution(21 species), and those of the rests were showed in order of NE > MC > AP. The sizes of isolated Selenastrum and Scenedesmus were $1.8\pm 1.4 \mu m$, $3.3\pm 0.9 \mu m$ in diameter and $6.4\pm 2.3 \mu m$, $13.6\pm 1.9 \mu m$ in length respectively. The morphology of isolated algae and NIES-collection strain was very similar each other, but the size was smaller isolated algae than that of NIES-collection. The optimum culture condition of isolated Selenastrum and Scenedesmus was about 30$\circ$C(25$\circ$C-35$\circ$C) in temperature and the maximum growth was appeared between 7,000 lux and 8,000 lux in the light intensity. The comparison of $\mu$(specific growth rate) on the concentration of nutrients such as nitrate and phosphate, isolated Selenastrum was appeared maximum it at 1.0 mg $NO_3-N/l$ but NIES-collection strain was showed 95% of maximum it at same nitrate concentration. Maximum g of isolated algae and NIES-collection strain in Scenedesmus onto nitrate concentration were very similar with the result of selenastrum. The specific growth rates of isolated algae and NIES-collection strain on the gradient concentration of phosphate were showed 0.72/day and 0.70/day at 0.02 mg $PO_4-P/l$ in Selenastrum but those of Scenedesmus were appeared 0.61/day and 0.57/day at same concentration $PO_4-P$.

• Journal of Microbiology and Biotechnology
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• 제16권7호
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• pp.1068-1077
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• 2006

Pseudomonas sp. PhCN strain, which has the potential to utilize phenol and cyanide as a sole carbon and nitrogen source, was isolated. A comparison of the effect of cyanide on phenol degradation and vice versa by strain PhCN showed that the degradation time was significantly delayed by an increase in either phenol or cyanide concentration, and the greatest activities were obtained in basal medium containing a low concentration of cyanide and phenol. This strain contained two plasmids of approximately 120 kb (pPhCN-1) and 110 kb (pPhCN-2). Plasmid curing experiments produced a plasmid-free strain as well as strains containing either the 120- or the 110 kb plasmid. The strains were tested for their ability to utilize phenol and KCN. The results demonstrated that the ability to utilize phenol was encoded by the 120 kb plasmid, whereas the ability to utilize cyanide appeared to be encoded by the chromosome.

• 한국정밀공학회지
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• 제27권4호
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• pp.87-94
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• 2010

When occlusal force is applied to a tooth, stress concentration occurs on the dental cervical line. This study investigated to find the maximum force and strain of natural teeth using an Instron and strain gauges, comparing the strain of cervical enamel using finite element analysis(FEA). Tests were conducted with a mandibular first premolar applying the conditions of occlusion. Then, the FEA was processed with the same as conditions of the fracture test. The test showed that the maximum force, maximum compressive strain and maximum tensional strain was $278{\pm}26$ N, $0.668{\times}10^{-3}{\pm}0.678{\times}10^{-3}$ and $0.248{\times}10^{-3}{\pm}0.102{\times}10^{-3}$, respectively. It was found that six of eight measured strains were within the range of estimated strains by the FEA. Even though it was assumed that properties of FE models were isotropic, it could prove useful as a reference in understanding the tendency of dental strain.

• Food Science and Biotechnology
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• 제17권6호
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• pp.1207-1213
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• 2008

The possible protective effects of highly zinc-containing yeast Saccharomyces cerevisiae, FF-10 strain, isolated from tropical fruit rambutan on acute alcoholic liver injury in rats were evaluated. Zinc concentration in this strain was 30.6mg%. The activities of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and $\gamma$-glutamyl transpeptidase ($\gamma$-GTP) were highly increased when alcohol was treated, relative to the normal rats. Also, a highly significant increase in the blood alcohol and acetaldehyde levels by alcohol treatment was observed. Administration of FF-10 strain markedly prevented alcohol-induced elevation of the activities of serum ALT, AST, and $\gamma$-GTP, and the levels of blood alcohol and acetaldehyde, and these reduced levels reached to that of normal rats. As compared with alcohol treated control rats, the FF-10 strain supplementation showed highly decreased the triglyceride concentration in serum. Alcohol treatment induced the marked accumulation of small lipid droplets, hepatocytes necrosis, and inflammation, but FF-10 strain administration attenuated to alcohol-induced accumulation of small lipid droplets and hepatocyte necrosis in the liver. Therefore, the current finding suggests that zinc-enriched yeast FF-10 strain isolated from tropical fruit rambutan may have protective effect against alcohol-induced hepatotoxicity.

• 비파괴검사학회지
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• 제26권5호
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• pp.329-335
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• 2006

기계구조물 설계시 파손이나 갑작스런 붕괴를 방지하기 위하여 응력집중을 실험적으로 측정해야 할 필요가 있다. 본 연구에서는 중앙에 원형구멍이 있는 외팔보 시편의 응력집중계수를 스트레인 게이지와 광탄성법으로 측정하였다. 스트레인 게이지법에서는 구멍 주위에 3개의 스트레인 게이지를 부착하여 측정된 값으로부터 외삽법을 사용하여 구멍에 인접한 지점에서 최대 변형률을 추정하였다. 광탄성법에서는 두 가지 측정법, 즉 배비넷-솔레일 보상법과 위상이동법을 이용하여 응력분포를 측정하였다. 스트레인 게이지와 광탄성법에 의한 측정값들을 서로 실험오차 이내로 근접하였다.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1211-1216
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• 2004

A MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) induced chromium resistant strain ($Cr^{r}18$) of unicellular cyanobacterium Anacystis nidulans has been isolated and characterized. The resistant strain could grow (although restricted to $50\%$ of control) in chromium concentration (180${\mu}M$) lethal to the wild-type. Sublethal ($160{\mu}M$) concentration of $Cr^{6+}$ significantly reduced (13-$37.5$) all the photosynthetic pigments of A. nidulans with maximum reduction in phycoerythrin followed by ChI $\alpha$. Pigments of A. nidulans were drastically decreased in lethal concentration of Cr^{6+} with maximum reduction in phycoerythrin ($75\%$) and allophycocyanin ($67.5\%$). Resistant strain $Cr^{r}18$ resisted toxic effects of sublethal and lethal concentrations of $Cr^{6+}$ on photosynthetic pigments as revealed by less decrease in pigments as compared to A. nidulans. Effect of $Cr^{6+}$ stress was also studied on nitrogen assimilation and phosphate uptake. Sublethal concentration of $Cr^{6+}$ drastically reduced ($71.5\%$) nitrate uptake by A. nidulans while a decrease of $29\%$ was observed in strain $Cr^{r}18$. Short (2 day) exposure of A. nidulans and its resistant strain $Cr^{r}18\;to\;Cr^{6+}$ did not affect nitrate reductase and glutamine synthetase (transferase), whereas longer (10 day) exposure to $Cr^{6+}$ lowered activities of both enzymes in A. nidulans but not significantly in the strain $Cr^{r}18$. Ammonium uptake by both strains was not affected by $Cr^{6+}$. Thus, $Cr^{6+}$ affected photosynthetic pigments, nitrogen assimilation, and phosphate uptake of A. nidulans, while strain $Cr^{r}18$ was able to resist toxic effects of the metal. Advantages of using strain $Cr^{r}18$ for bioremediation purposes have been evaluated by studying $Cr^{6+}$ removal from the solution. Resistant strain $Cr^{r}18$ was able to remove $33\%$ more $Cr^{6+}$ than A. nidulans and thus it can prove to be a good candidate for bioremediation of $Cr^{6+}$ from polluted waters.

• 기술사
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• 제19권4호
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• pp.5-10
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• 1986

On SWS 41 Plates jointed by the F11T M 20 high strength bolts the study on stress behavior and safety degree until rupture in static tensile tests were performed. By these results, in case of no clamping force stress concentration was extremed for strain of about 10% higher ratio. Elastic strain occurred to change of test specimens depth by the load and plastic strain occurred to local minute sleep after elastic strain. compared shear stress with tension stress from the fracture load it was showned lower values than the maximum shear stress theory and stress strain energy theory.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.150-153
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• 2001

In this paper, the tensile test of three kinds of the specimens was performed. Type I specimen is without notch and type II, III specimens have a radius of semi-circular edge crack of 2.5mm, 4.0mm. The tensile load(20kN and 30kN) was applied to the specimen by Universal Testing Machine. 3D-ESPI system and strain gauge measured simultaneously the strain in the center of the specimen and near the edge crack. The test results were compared with each other. Moreover, the stress concentration factor based on geometric information was calculated to confirm the accuracy of the strain measured by 3D-ESPI system. The calculated strain was compared with the measured one by 3D-ESPI system. As a result, it was confirmed that 3D-ESPI system measured the right strain near the semi-circular edge crack of the specimens.