• 산업식품공학
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• 제21권4호
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• pp.403-408
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• 2017

양파를 이용하여 식초를 제조하기 위하여 막걸리로부터 분리된 내산성과 내알코올성이 우수하고 산생성능이 높은 Aectoacter orientalis MAK88를 사용하였다. 양파 추출액에 A. orientalis MAK88의 종배양액을 접종하여 초산 발효를 실시하였을 경우, 발효 최적 조건을 조사하였다. 앙파 추출액 중의 초기 에탄올 농도는 5% (v/v)가 최적이었으며, 발효 144시간에서의 산도는 4.31%이었다. 초기 초산 농도는 1% (v/v)가 최적으로 발효 144시간에서의 최종 산도는 5.32%였다. 최적 발효온도는 $28^{\circ}C$로 확인되었다. 양파 착즙액은 통 양파를 $121^{\circ}C$에서 15분간 가열한 뒤 가압 착즙 후 여과한 다음 $121^{\circ}C$에서 15분간 살균하여 제조한 것이 발효에 가장 적합하였으며, 희석하지 않은 착즙 원액을 사용하는 것이 가장 좋았다.

• Applied Biological Chemistry
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• 제40권1호
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• pp.18-22
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• 1997

Bifidobacterium longum을 고농도 배양하기 위하여 최적 생육 조건을 조사하고 cross-flow filtration으로 생육 저해 대사산물인 lactic acid와 acetic acid를 제거하면서 균체 순환 배양을 사용하였다. 회분 배양에서는 탄소원으로 glucose를 50 g/l 농도로 사용하고 초기 pH 6.5인 경우 생육이 가장 높았다. B. longum을 cross-flow filtration으로 12시간 배양한 결과, 희석속도 $0.31h^{-1}$에서 최대 균체농도에 도달하여 16.4g/l의 건조균체량을 얻었으며 이로써 회분 배양시 보다 약 4배 높은 균체를 생산하였다.

• 한국수소및신에너지학회논문집
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• 제13권1호
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• pp.42-51
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• 2002

Methane can be converted directly to hydrogen by pyrolysis. The reaction is highly endothemic and heat must be supplied at high temperatures. Gibbs free energy minimization calculations have been carried out for the methane pyrolysis to determine equilibrium products. The calculation parameters are the temperature, the initial H/C ratio, the pressure and Gibbs energies of each substance. Methane, ethylene, acetylene, benzene, naphthalene, and hydrogen are the main products. Excluding hydrogen, it is observed that ethylene and aromatics(benzene+naphthalene) are predominant products below 1400K, whereas acetylene is significantly formed above 1400K. Hydrogen dilution increases the selectivities for ethylene and acetylene and decreases the selectivity for aromatics. Increasing the pressure also decreases the decomposition of methane.

• 한국미생물·생명공학회지
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• 제19권4호
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• pp.419-427
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• 1991

에탄올의 발효 생산성을 높이기 위해서는 발효조의 균체농도를 높여 고농도의 배양을 해야하며 또한 에탄올에 의한 저해 작용을 감소시켜 비생산성을 향상시키기 위해서는 발효액 중에 축적되는 에탄올을 배출 시킬 필요가 있다. 이와 같은 목적으로 본 연구에서는 고분자 hollow fiber membrane, ceramic filter를 이용하여 가장 중요한 조작 변수인 희석율과 bleed stream ratio가 에탄올 생산성에 미치는 영향 및 조작의 문제점과 장기 조업 가능성을 검토하였다.

• Journal of Microbiology and Biotechnology
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• 제23권10호
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• pp.1460-1471
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• 2013

Microalgal biofuel production from wastewater has economic and environmental advantages. This article investigates the lipid production from high chemical oxygen demand (COD) bioethanol wastewater without dilution or additional nutrients, using a newly isolated heterotrophic microalga, Chlorella vulgaris LAM-Q. To enhance lipid accumulation, the combined effects of important operational parameters were studied via response surface methodology. The optimal conditions were found to be temperature of $22.8^{\circ}C$, initial pH of 6.7, and inoculum density of $1.2{\times}10^8cells/ml$. Under these conditions, the lipid productivity reached 195.96 mg/l/d, which was markedly higher than previously reported values in similar systems. According to the fatty acid composition, the obtained lipids were suitable feedstock for biodiesel production. Meanwhile, 61.40% of COD, 51.24% of total nitrogen, and 58.76% of total phosphorus were removed from the bioethanol wastewater during microalgal growth. In addition, 19.17% of the energy contained in the wastewater was transferred to the microalgal biomass in the fermentation process. These findings suggest that C. vulgaris LAM-Q can efficiently produce lipids from high-concentration bioethanol wastewater, and simultaneously performs wastewater treatment.

• Nuclear Engineering and Technology
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• 제38권3호
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• pp.301-310
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• 2006

Destructive methods were used for the burnup determination of U-Zr alloy nuclear fuel irradiated in the High-flux Advanced Neutron Application Reactor (HANARO) at KAERI. The dissolution rate of unirradiated U-Zr alloy fuel in $HNO_3$/HF mixtures was investigated for the experimental conditions of a different temperature, and initial concentrations of HF and $HNO_3$. The irradiated U-Zr alloy fuel specimen was dissolved in a mixed acid condition of 3 M HNO3 and 1 M HF at $90^{\circ}C$ for 8 hours under reflux. The total burnup was determined from measurement of the Nd isotope burnup monitors. The method includes U, Pu, $^{148}Nd,\;^P{145}Nd+^{146}Nd,\;^{144}Nd+^{143}Nd$ and total Nd isotopes determination by the isotope dilution mass spectrometric method (IDMS) using triple spikes $(^{233}U,\;^{242}Pu\;and\;^{150}Nd)$. The effective fission yield was calculated from the weighted fission yields averaged over the irradiation period. The results are compared with that obtained by the destructive -spectrometric measurement of the $^{137}Cs$ monitor.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1650-1660
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• 2020

Comparing with the large containment, the gas can not flow freely within the local compartment due to the small volume of the compartment in case of serious accident, which affects the hydrogen flow distribution, and it will determines the location where high concentration occurs in compartment. In this paper, hydrogen distribution and possible hydrogen risk in the vessel under the different conditions are investigated. The results show that when the initial gas momentum is increased, the ability of gas enters into the upper region of the vessel will be strengthened, and the hydrogen volume fraction in the upper region of the vessel is higher. Comparing with horizontal source direction, when source direction is vertically towards upper space, hydrogen is more likely to accumulate in the upper region of the vessel. With the increasing of steam mass flow, the dilution effect of steam on the hydrogen volume fraction will be strengthened, while the pressure in the vessel is also increased. When steam flow is decreased, the hydrogen explosion risk is higher in the vessel. The experiment data can provide technical support for the validation of the CFD software and the mitigation of hydrogen risk in the containment compartment.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1133-1136
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• 2004

The need for highly reliable methods for the determination of trace metals is recognized in analytical chemistry and environmental science. A method based on the cloud-point extraction (CPE) technique for the trace analysis of Pb and Cu in water samples is described in this study. The analytes in the initial aqueous solution are complexed with pyrogallol, and 0.1%(w/v) Triton X-114 is added as surfactant. Following phase separation at $50^{\circ}C$, based on the cloud point of the mixture and dilution of the surfactant-rich phase with acidified methanolic solution, the enriched analytes are determined by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, the enrichment factors of Pb and Cu were found to be 72 and 85, respectively. Under optimum conditions, the preconcentration of 60 mL of samples in the presence of 0.1%(w/v) Triton X-114 permitted the detection of 0.4 ${\mu}gL^{?1}$ of Pb and 0.05 ${\mu}gL^{?1}$ of Cu. The proposed method was applied successfully to the determination of Pb and Cu in water samples.

• 생명과학회지
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• 제7권4호
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• pp.377-383
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• 1997

The acute toxicity effect of triorganotin of trioganotin on the growth of microalgae and shellfish was investigated through flask culture. The value of 120 hr-LC$_{50}$ that is the median lethal concentration of TBTO on the shellfish (R. philipinarum) was found to be 6 $\mu$g/L. The acute toxicity effect of TBTO on T. suecica was obviously shown even at the concentration of 0.5 $\mu$g/L, and the effect diminished as the initial cell density increased. The effect also diminished less in the experiment done under aeration than in that done under non-aeration. To design a chemostat system for the test of chronic toxicity, the culture of T. suecica was executed in photobioreactor. In batch culture, the profiles of chlorophyII a and D.C.W. showed the growth of T. suecica very well, and the maximum specific growth rate was estimated to be 0.54 d$^{-1}$. with this value, as a dilution rate in contimuous culture, pH was nicely maintained between 7 and 9 when air was supplied with 3% CO$_{2}$. From all results and the natural environment of clam, a novel chemostat system was invented. Through this system, we can observe each independent toxicity effect of TBTO and plankton and combined toxicity effect as well.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.413-418
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• 1996

The main purpose of this paper is to develop the modified LTC code for accurate analysis of the boron concentration behavior of all components in the Nuclear Steam Supply System (NSSS). This is achieved by adapting a multi-cell mad to the existing Long Term Cooling (LTC) code. To verify the modified LTC, the simulated results were compared with the actual test results measured during YGN 4 initial criticality test. It was shown that the simulated results of this modified LTC were in good agreement with the actual test results. Also, the boron concentration behavior analysis were performed using the modified LTC code for both direct and indirect dilution/boration nude using YGN 3,4 design data. This modified LTC code can provide a valuable information in predicting boron concentration behavior during power maneuvering such as startup operation, shutdown operation and load follow operation. It is expected that the modified LTC can be applied to both on-line and off-line mode using Plant Computer System(PCS).