• 한국환경과학회지
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• 제6권2호
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• pp.113-124
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• 1997

The basic mechanism of the granular sludge formation which is the most important factor in the start-up and stable operators is not confirmed yet. In this study, the effect of granular sludge formation was investigated with the different substrate concentrations and the various ratios of substrate supply/deficiency. The granular sludge formation in the UASB reactor was closely related to the substrate concentrations and the ratio of substrate supply/deficlency The granular sludge formation was not accelerated at low substrate concentration. It was convinced that granular sludge formation was accelerated when the substrate supply with high concentration was stopped at UASB reactor. From this experiment, it was estimated that granular sludge was formed by the combination of hydrogen utilizing bacteria that form hydrogen condition and acid forming bacteria at substrate deficit condition by mutual symbiosis. Though the removal efficiency of organic matter was decreased as the influent substrate concentration was Increased, the higher the influent substrate the better the granular sludge formation.

• Food Science and Biotechnology
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• 제16권6호
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• pp.999-1005
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• 2007

An oil-in-water (O/W) emulsion [20 wt% com oil, 0.5-6.0 wt% fish gelatin (FG), pH 3.0] was produced by high pressure homogenization, and the influence of pH, protein concentration, and homogenization condition on the formation of FG-stabilized emulsions was assessed by measuring particle size distribution, electrical charge, creaming stability, microstructure, and free FG concentration in the emulsions. Optical microscopy indicated that there were some large droplets ($d>10\;{\mu}m$) in all FG-emulsions, nevertheless, the amount of large droplets tended to decrease with increasing FG concentration. More than 90% of FG was present free in the continuous phase of the emulsions. To facilitate droplet disruption and prevent droplet coalescence within the homogenizer, homogenization time was adjusted in O/W emulsions stabilized by 2.0 or 4.0 wt% FG. However, the increase in the number of pass rather promoted droplet coalescence. This study has shown that the FG may have some limited use as a protein emulsifier in O/W emulsions.

• 한국분무공학회지
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• 제4권4호
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• pp.1-8
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• 1999

The concentration and spatial distribution of vapor phases in DI (Direct Injection) gasoline spray were measured quantitatively by exciplex fluorescence method. Fluorobenzene and DEMA (diethylmethylamine) in a solution of hexane were used as the exciplex-forming dopants. The fluorescence intensity of vapor phase were obtained by ICCD camera with the appropriate filter The relationship between fluorescence intensity and vapor concentration was induced fer the purpose of a quantitative analysis. The 2-D vapor/liquid images of fuel spray were captured under the evaporation condition, and the spatial distribution of vapor concentration was obtained. The spatial distribution of liquid phase had hollow-cone shape. And the vapor phase was widely distributed in the whole spray. The behavior of vapor phase was significantly affected by second flow such as entrainment, vortex, while that of liquid phase was scarcely affected.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2765-2770
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• 2008

The purpose of tunnel ventilation system for long road tunnels is to keep certain levels of Visibility Index and the concentration of CO. Additional equipments such as jet fans are used in road tunnel to discharge pollutants in the road tunnel. The control algorism of tunnel ventilation system takes the value of sensors as input, and then gives the operation method of jet fans in tunnel as output. Information on the variation of CO concentration in tunnel when jet fans are running is needed to minimize their operation time. Numerical analysis is used in this paper because of the difficulty of conducting experiments under standard condition for ventilation of road tunnel. The concentration of CO has been calculated by using 3-dimensional CFD under transient condition with speed of cars, quantity of air ventilation, and the results for various operation position of jet fans are compared.

• 한국세라믹학회지
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• 제36권8호
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• pp.853-858
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• 1999

To investigate the effect of H2 flow rate and TMS[Si(CH3)4] concentration on synthesizing ultrafine ${\beta}$-SiC powder by vapor phase reaction the experiment was performed at 1100$^{\circ}C$ of the reaction temperature under the condition of 200-2000 cc/min of H2 gas flow rate and 1-10% of TMS concentration respectively. The shape of ${\beta}$-SiC particles synthesized was spherical and the size of particles decreased and the distribution of particles was more uniform with increasing H2 gas flow rate. In this case Si powders were coexisted with ${\beta}$-SiC Pure and ultrafine ${\beta}$-SiC powders without Si were obtained under the condition of above 2% of TMS concentration and below 1500 cc/min of H2 gas flow rate.

• Biotechnology and Bioprocess Engineering:BBE
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• 제3권2호
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• pp.109-111
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• 1998

The effect of dissolved oxygen concentration on the metabolism of glucose in Pseudomonas putida BM014 was investigated. Glucose was completely converted to 2-ketogluconate via extracellular oxidative pathway and then taken up for cell growth under the condition of sufficient dissolved oxygen concentration. On the other hand, oxygen limitation below dissolved oxygen tension (DOT) value of 20% of air saturation caused the shift of glucose metabolism from the extracellular oxidative pathway to the intracellular phosphorylative pathway. Specific activities of hexokinase and gluconate kinase in intracellular phosphorylation pathway decreased as the DOT increased, while 2-ketogluconokinase activity in extracellular oxidative pathway increased under the same condition. This result can be usefully applied to microbial transformation of glucose to 2-ketogluconate, the synthetic precursor for iso-vitamine C, with almost 100% yield via extracellular oxidation by simple DOT control.

• 한국표면공학회지
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• 제29권2호
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• pp.132-139
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• 1996

Experiments on the automatic control of NaOH concentration and on the spraying condition of NaOH solution in the alkaline degreasing process of a continuous hot-dip galvanizing line have been carried out in order to improve degreasing performance of a galvanizing sheet steel using laboratory degreasing and galvanizing simulators. The concentration of NaOH for the good degreasing has been determined to be 6.0% and more and this concentration has been able to be automatically well controlled within $\pm$0.1% by employing a solution electrical conductivity meter under a flow injection analysis condition rather than by employing a sodium ion selective electrode in the degreasing simulator. Frequent blocking of the spraying nozzles of the solution has been reduced considerably by the set-up and periodical operation of an automatic valve system in the nozzle system. By applying this automatic valve system and by automatic controlling the NaOH concentration and other ordinary variables in the degreasing process, the degreasing performance has been increased from the conventional 76% to the new 85%.

• 한국식품과학회지
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• 제31권4호
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• pp.938-944
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• 1999

도라지의 색상발현을 위하여 반응표면분석법으로 도라지의 threonine 침지농도 및 볶음조건에 따른 도라지차의 기계적 색도 및 관능적 색상 변화를 모니터링 하였다. 기계적 색도와 관능적 색상에 대한 회귀식의 $R^{2}$는 모두 0.87 이상으로 5% 수준에서 유의성이 인정되었다. 백색도가 가장 높은 침지 및 볶음조건은 threonine 농도 0.09%에서 침지한 후 건조하여 $142.37^{\circ}C$에서 21.94분 볶음처리하는 것으로 나타났다. 적색도가 가장 높은 침지 및 볶음조건은 threonine 농도 1.24%에서 침지한 후 건조하여 $154.01^{\circ}C$에서 28.59분 볶음처리하는 것으로 나타났고, 가장 낮은 침지 및 볶음조건은 threonine농도 1.67%에서 침지한 후 건조하여 $137.61^{\circ}C$에서 24.62분 볶음처리하는 것으로 나타났다. 황색도가 가장 높은 침지 및 볶음조건은 threonine 농도 1.10%에서 침지한 후 건조하여 $154.72^{\circ}C$에서 27.12분 볶음처리하는 것으로 나타났다. 관능적 특성으로서 도라지차의 색상에 대한 관능평점은 threonine 농도 1.25%, 볶음온도 $141.81^{\circ}C$및 볶음시간 34.14분에서 가장 높았다.

• 현장농수산연구지
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• 제11권1호
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• pp.95-101
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• 2009

약용 및 관상식물로 개발가치가 있는 백리향의 종자발아 및 삽목조건 구명을 위한 몇 가지 실험결과는 아래와 같다. 종자발아는 20℃ 광 조건에서 89%의 발아율로 가장 좋았다. 적정 삽목시기는 5월20일이 94%의 발근율로 가장 양호했고, 삽목용토는 단용보다는 peatmoss(50%) + perlite(50%) 혼용처리에서 좋았으며 삽목전 삽수의 IBA 처리농도는 100mg/L 침지처리에서 96% 발근율을 나타내었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.93-100
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• 2000

In this study, we used photoelastic coating method which is a kind of model test for examining the stress condition of rock masses around underground structures. Using this method, we could know adaptability and usefulness of photoelastic coating method for various shape of tunnel models. And, in spite of higher cross section efficiency, square shape model showed unstable status because of high stress concentration. So, we cut the slits at the each corner of tunnel, and we could make more stable stress condition by means of moving high stress concentration to rock mass.