• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.35-38
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• 2003

The purpose of this study is to investigate the manufacture of light weight concrete panel using the artificial light-weight aggregate as a part of the substitution of foamed styrene and polyurethane because of narrow allocable temperature Bone in use. The experimental parameter of this study is 40, 60 and 8$0^{\circ}C$ of curing temperature at 100% relative humidity and the type of admixture such as cement, 6mm glass fiber and St/BA emulsion. Testing item is compressive and flexural strength and strength of specimen cured at standard condition is compared to that of specimen cured at 40, 60 and 8$0^{\circ}C$ of curing temperature at 100% relative humidity. As a result or this, it was revealed that the maximum or strength is developed in 6$0^{\circ}C$ or cure temperature at 100% relative humidity in case of the most of the specimen. Specimens modified by St/BA emulsion show the highest development of strength dependent on the curing tmeperature. So, it seems to be effective that evaporation curing method shoud be considered to curing the specimen as the panel core.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1369-1378
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• 2007

For effective exopolysaccharide production and mycelial growth by a liquid culture of Fomitopsis pinicola in an air-lift bioreactor, the culture temperature, pH, carbon source, nitrogen source, and mineral source were initially investigated in a flask. The optimal temperature and pH for mycelial growth and exopolysaccharide production were $25^{\circ}C$ and 6.0, respectively. Among the various carbon sources tested, glucose was found to be the most suitable carbon source. In particular, the maximum mycelial growth and exopolysaccharide production were achieved in 4% glucose. The best nitrogen sources were yeast extract and malt extract. The optimal concentrations of yeast extract and malt extract were 0.5 and 0.1%, respectively. $K_2HPO_4\;and\;MgSO_4{\cdot}7H_2O$ were found to be the best mineral sources for mycelial growth and exopolysaccharide production. In order to investigate the effect of aeration on mycelial growth and exopolysaccharide production in an air-lift bioreactor, various aerations were tested for 8 days. The maximum mycelial growth and exopolysaccharide production were 7.9 g/l and 2.6 g/l, respectively, at 1.5 vvm of aeration. In addition, a batch culture in an air-lift bioreactor was carried out for 11 days under the optimal conditions. The maximum mycelial growth was 10.4 g/l, which was approximately 1.7-fold higher than that of basal medium. The exopolysaccharide production was increased with increased culture time. The maximum concentration of exopolysaccharide was 4.4 g/l, which was about 3.3-fold higher than that of basal medium. These results indicate that exopolysaccharide production increased in parallel with the growth of mycelium, and also show that product formation is associated with mycelial growth. The developed model in an air-lift bioreactor showed good agreement with experimental data and simulated results on mycelial growth and exopolysaccharide production in the culture of F. pinicola.

• Korean Journal of Weed Science
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• v.30 no.1
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• pp.50-57
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• 2010

This experiment was conducted to investigate seedling emergence of Humulus japonicus in Seoul and Suwon and to predict its seedling emergence in various locations in Korea. Non-linear regression analysis to fit Gompertz model to accumulated seedling emergence of H. japonicus was performed to describe its seedling emergence. Parameter estimates from the non-linear regression and estimated effective accumulated temperature required for its seedling emergence were further used to predict seedling emergence of H. japonicus in 8 major geographical regions of Korea. Seedling emergence of H. japonicus versus effective accumulated temperature was well described by Gompertz model in both Seoul and Suwon. Effective accumulated temperatures required for the first seedling emergence and 50% of the maximum seedling emergence were estimated to be $56.7^{\circ}C$ and $76.3^{\circ}C$, respectively. Therefore, the dates for the first seedling emergence of H. japonicus were predicted to be 21 and 30 March in Daegu and Daejeon, while 4 and 6 April in Suwon and Chuncheon, respectively. The dates reaching 50% of maximum seedling emergence were also predicted to be 25 March in Daegu, while 3, 8 and 9 April in Daejeon, Suwon and Chuncheon, respectively.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.1
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• pp.109-118
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• 1997

In this study, we examined the structural analysis of water demand fluctuation for water distribution control of water supply network. In order to analyze for the length of stationary time series, we calculate autocorrelation coefficient of each case equally divided data size. As a result, it was found that, with the data size of around three months, any case could be used as stationary time series. we analyze cross-correlation coefficient between the daily water consumption's data and primary influence factors. As a result, we have decided to use weather conditions and maximum temperature as natural primary factors and holidays as a social factor. Applying the multiple ARIMA model, we obtains an effective model to describe the daily water demand prediction. From the forecasting result, even though we forecast water distribution quantity of the following year, estimated values well express the flctuations of measurements. Thus, the suitability of the model for practical use can be confirmed. When this model is used for practical water distribution control, water distribution quantity for the following day should be found by inputting maximum temperature and weather conditions obtained from weather forecast, and water purification plants and service reservoirs should be operated based on this information while operation of pumps and valves should be set up. Consequently, we will be able to devise a rational water management system.

• Journal of the Korean Ceramic Society
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• v.32 no.6
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• pp.659-668
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• 1995

Zirconium carbide was prepared from the mixture of metal zirconium and carbon powders in argon atmosphere by Self-propagating High-temperature Synthesis (SHS) in order to obtain the best carbon source and dilution contents. The most exellent result was obtained in the case that active carbon was added as a starting material, 20~30 wt% dilution content. From thermal profile analysis an apparent activation energy of 118 KJ/mol was calculated. The maximum heating rate achieved during 15 wt% ZrC reaction by product dilution method was approximately 1.54$\times$105 K/s. Coupling this value with the measured wave velocity of 1.026cm/s yielded a maximum thermal gradient fo $1.5\times$105 K/cm. Using the definition of t* and the measured wave velocity, the effective thermal diffusivity, $\alpha$, was calculated to be 0.62$\times$102 $\textrm{cm}^2$/s.

• Food Science and Preservation
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• v.15 no.1
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• pp.66-73
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• 2008

Response surface methodology (RSM) was applied for monitor the yields of desirable substances from fig (Ficus carica L) under different extraction conditions. The maximum yield was 66.46% at 22.08 mL/g of solvent to sample ratio, $90.59^{\circ}C$ extraction temperature and 148.04 min extraction time. The maximum total phenolics was $121.31{\mu}g/mL$ at 17.87 mL/g, $98.82^{\circ}C$, and 130.80 min. The maximum electron donating ability was 54.09% at $121.31{\mu}g/mL$, 18.13 mL/g, and $98.81^{\circ}C$. The maximum value of protease activity was 54.51 unit/min at 17.45 mL/g, $99.01^{\circ}C$, and 131.43 min. In addition, the maximum value of reducing sugar content was 19.14 mg/mL in 22.66 mL/g, $86.30^{\circ}C$, and 153.59 min. The optimum conditions estimated by RSM for maximal extraction of the effective components were $17{\sim}25$ mL/g of solvent to sample ratio, $80{\sim}100^{\circ}C$ of extraction temperature, and $100{\sim}170$ min of extraction time.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.194-198
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• 2005

Growth curves of Listeria monocytogenes in modified surimi-based imitation crab (MIC) broth were obtained by measuring cell concentration in MIC broth at different culture conditions [initial cell numbers, $1.0{\times}10^{2},\;1.0{\times}10^{3}\;and\;1.0{\times}10^{4}$, colony forming unit (CFU)/mL; temperature, 15, 20, 25, 37, and $40^{\circ}C$] and applied to Gompertz model to determine microbial growth indicators, maximum specific growth rate constant (k), lag time (LT), and generation time (GT). Maximum specific growth rate of L. monocytogenes increased rapidly with increasing temperature and reached maximum at $37^{\circ}C$, whereas LT and GT decreased with increasing temperature and reached minimum at $37^{\circ}C$. Initial cell number had no effect on k, LT, and GT (p > 0.05). Polynomial and square root models were developed to express combined effects of temperature and initial cell number using Gauss-Newton Algorism. Relative coefficients of experimental k and predicted k of polynomial and square root models were 0.92 and 0.95, respectively, based on response surface model. Results indicate L. monocytogenes growth was mainly affected by temperature and square root model was more effective than polynomial model for growth prediction.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.1
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• pp.37-40
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• 2003

The antibacterial action of violet pigment, a mixture of violacein and deoxyviolacein, isolated from phychrotrophic bacterium RT102 strain was examined, and the operational conditions for the effective production of violet pigment were studied. The antibacterial activity of the violet pigment was confirmed for several bacteria such as Bacillus licheniformis, Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, and Pseudomonas aeruginosa, and the high concentration of violet pigment, above about 15mg/L, caused not only growth inhibition but also death of cells. The growth properties of RT102 strain were clarified under various incubation conditions such as pH, temperature, and dissolved oxygen concentration. The maximum violet pigment concentration, i.e. 3.7 g/L, and the maximum productivity of violet pigment, i.e. 0.12 g .L$\^$-1/H$\^$-1/, were obtained in a batch culture of pH 6, 20$^{\circ}C$, and 1 mg/L of dissolved oxygen concentration.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3140-3141
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• 2008

The output power efficiency of the fuel cell system depends on the demanded current, stack temperature, air excess ratio, hydrogen excess ratio and inlet air humidity. Thus, it is necessary to determine the optimal operation condition for maximum power efficiency. In this paper, we developed a dynamic model of fuel cell system which contains mass flow model, diffusivity gas layer model, membrane hydration and electrochemistry model. In order to determine the maximum output power and minimum use of hydrogen in a certain power condition, response surface methodology (RSM) optimization based on the proposed PEMFC stack model is presented. The results provide an effective method to optimize the operation condition under varied situations.

• Solar Energy
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• v.19 no.4
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• pp.1-10
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• 1999

The phenomena of energy separation through the vortex tube was investigated experimentally, to see the effect of nozzle area ratio and partial admission rate on the energy separation and cooling capacity. The experiment was tarried out with various nozzle area ratios from 0.031 to 0.232 and partial admission rate from 0.176 to 0.956 by varying input pressure($0.2{\si\m}0.5$ MPa) and cold air mass fraction($y=0.1{\sim}1.0$). From the experimental result, we found the optimum nozzle area ratio and the effective partial admission rate for the available use and best cooling performance in given operation condition. While the maximum drop of cold air temperature was observed at around y=0.3 and $S_n=0.155$, the maximum cooling capacity was observed at around y=0.6 and $S_n=0.094$.