• 한국식품영양학회지
• /
• 제12권6호
• /
• pp.569-574
• /
• 1999

Response surface methodology(RSM) was applied to determine the optimum heating conditions(tem-perature and time) for the inactivation of bacteria associated with food hygiene. Coefficients of determinations(R2) for the cell growth were 0.9155(P<0.05) in Pseudomonas aeruginosa 0.8997(P<0.05) in Escherichia coli 0.9690(P<0.01) in Salmonella typhimurium 0.9393(P<0.05) in Enterobacter aerogenes and 0.7905 in Vibrio parahaemolyticus. The growth of strains was significantly affected by the temperature and time and reaction to temperature was most closely correlated to the inhibition of growth. On the basis of superimposed contour maps of cell growth the optimum range of heating conditions were 55.62-6$0^{\circ}C$ and 19.25-30 min.

• KSBB Journal
• /
• 제13권4호
• /
• pp.431-437
• /
• 1998

Optimal media and cultural conditions for the production of prodigiosin-like pigment were established using Serratia sp. KH-95. Glucose and phosphate(K2PO4) stimulated the cell growth, but inhibited the production of pigment at concentration levels of above 10 g/L and 2.0 g/L, respectively. Addition of soy been oil or rice oil to the production medium accelerated cell growth up to more than 2-3 times, but the production of prodigiosin increased about 15-20% in spite of the good cell growth. The effect of pH on the production of pigment was investigated in a 5 liter-bioreactor. When the pH of culture broth was maintained below 8.0, most of pigment was attached to the surface of cells. When the pH of culture broth was above 8.5, however, about 70% of total pigment was suspended in the supernatant of the broth. The cell growth and production of pigment were inhibited at dissolved oxygen concentration of below 10% of air-saturation.

• 한국정밀공학회지
• /
• 제19권8호
• /
• pp.92-99
• /
• 2002

This work investigated the optimal condition for an uniform deposition growth rate in the vertical cylindric CVD chamber. Heat transfer, surface chemical reaction and mass diffusion in the flow field of CVD chamber h,id been computed using Fluent v5.3 code. A SIMPLE based finite Volume Method (FVM) was adopted to solve the fully elliptic equations for momentum, temperature and concentration of a chemical species. The numerical analysis results show good agreements with the measurements obtained by N. Yoshikawa. The results obtained by the numerical analysis showed that the film growth rate in the center of a susceptor is increasing, as the inner flow approaches to the forced convection. To the contrast, as it approaches to the natural convection, that in the outside of a susceptor is increasing. As the Reynolds number increases, the uniformity may not hold due to the larger temperature gradient at a susceptor surface. Therefore, when the temperature gradient on the surface of a susceptor is zero, the film growth rate becomes uniform on most surface.

• 한국수소및신에너지학회논문집
• /
• 제19권1호
• /
• pp.41-48
• /
• 2008

Fermentative $H_2$ production was studied using microbial consortia isolated from heat-treated ($90{\circ}C$, 20 min) sewage sludge. Important parameters investigated were carbon(C) and nitrogen(N)-sources, C/N ratio, phosphate concentration, pH and temperature during anaerobic cultivation in serum bottles. Starch, ribose, sucrose and glucose were good C-sources for the culture growth and $H_2$ production. Yeast extract was better N-source than $(NH_4)_2SO_4$ or peptone when individually added to the synthetic media, however the combination of above three N-sources exhibited the additional effect for cell growth and $H_2$ evolution. Addition of 100 mM phosphate as a buffering agent prevented the rapid pH drop during the cultivation. The optimum initial pH for the cell growth was at 7.0, whereas $H_2$ production was observed at pH 5.5. Optimum temperature for the cell growth and $H_2$ production was $37{\circ}C$. Initial C/N ratio of 1.22 in the media using glucose and yeast extract as the C- and N-sources, respectively, showed the $H_2$ yield 1.0 mol $H_2$/mol glucose.

• 한국미생물·생명공학회지
• /
• 제46권4호
• /
• pp.377-389
• /
• 2018

In this study, a novel microalgal strain, Desmodesmus sp. KAERI-NJ5, was isolated, identified, and evaluated as a candidate for biodiesel feedstock. In a preliminary study, the effects of four general microalgal growth factors, including temperature, pH, light intensity, and concentration of nitrogen source ($KNO_3$), on the microalgal photoautotrophic growth were evaluated. With the exception of light intensity, the growth factors needed to be optimized for the microalgal biomass production. Optimization was done using response surface methodology. The optimal conditions for biomass production were pH 6.54, $27.66^{\circ}C$, and 0.52 g/l $KNO_3$. The biomass production at the optimal conditions was 1.55 g/l, which correlated well with the predicted value of 1.5 g/l. The total lipid and fatty acid methyl ester contents of the cells grown at the optimal conditions were 49% and 21.2% of cell dry weight, respectively. To increase the lipid content of the biomass, microalgae were challenged by nitrogen starvation. Enhancement of total lipid and fatty acid content up to 52.02% and 49%, respectively, were observed. Lipid analysis of the nitrogen-starved cells revealed that C16 and C18 species accounted for 95.9% of the total fatty acids. Among them, palmitic acid (46.17%) and oleic acid (39.43%) dominantly constituted the algal fatty acids. These results suggest Desmodesmus sp. KAERI-NJ5 as a promising feedstock for biodiesel production.

• Structural Engineering and Mechanics
• /
• 제25권3호
• /
• pp.275-289
• /
• 2007

In this paper a brief overview of methods to assess the reliability of mechanical systems and structures is presented. A selection of computational procedures, stochastic structural dynamics, stochastic fatigue crack growth and reliability based optimization are discussed. It is shown that reliability based methods may form the basis for a rational decision making.

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
• /
• pp.72-72
• /
• 2008

• 한국생명과학회:학술대회논문집
• /
• 한국생명과학회 2006년도 제47회 학술심포지움 및 추계국제학술대회
• /
• pp.111.2-111.2
• /
• 2006

• 한국생명과학회:학술대회논문집
• /
• 한국생명과학회 2002년도 제35회 학술심포지움 및 춘계학술대회
• /
• pp.75-75
• /
• 2002

• 한국생명과학회:학술대회논문집
• /
• 한국생명과학회 2002년도 제35회 학술심포지움 및 춘계학술대회
• /
• pp.76-76
• /
• 2002