• 한국식품과학회지
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• 제33권1호
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• pp.1-6
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• 2001

수용성 단백질을 첨가한 유화물을 형광 조명하에서 $5^{\circ}C$에서 8일간 저장하였을 때 POV(Peroxide value) 값의 변화를 측정한 결과 저장 초기에 유의적인 증가를 나타냈고 TBA(Thiobarbituric acid) 값의 변화에서도 저장 4일까지 상당량의 카르보닐 화합물이 발생하는 것으로 나타나서 일반적인 지방의 자동산화와는 다른 양상을 보였고 대두유 같은 유지에서 저장 초기에 나타나는 변향의 발생과 비슷한 결과를 나타냈다. 이러한 원인으로는 육색소인 myoglobin에 의한 산화로 사료되며 superoxide anion보다는 일중항 산소에 의한 산화일 가능성이 높은 것으로 사료된다. 빛을 차단하였을 때에도 전체적인 양상을 비슷했지만 산화생성물의 생성량이 빛을 쪼였을 때보다 약간 적었고 일중항 산소의 효과도 두드러지지 않았으며 유화물 제조과정 중에 생성된 일중항 산소가 저장 초기의 변향에 관여하였을 것으로 추정된다. 수용성 단백질을 첨가하지 않은 경우에는 과산화물의 생성량이 지속적인 증가를 나타내서 수용성 단백질 처리구와 차이를 보였는데 과산화물의 분해속도가 수용성 단백질 처리구에 비해 작은 것으로 사료되며 특히 저장 4일 이후에 카르보닐 화합물의 생성속도가 줄어드는 것으로 나타났다. 저장 중에 일중항 산소의 발생 가능성이 있는 것으로 나타났으나 대두유의 탈색과정에서 잔존하였을 식물성 감광체가 원인일 것으로 추정된다. 빛을 차단하였을 때에는 저장 초기의 산화생성물 발생량이 빛을 쪼였을 때보다 미미했고 소거제 처리에 대한 효과도 드러나지 않아서 지질의 산화에 대한 빛의 촉진효과를 나타내는 결과라고 사료된다.

• 대한기계학회논문집B
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• 제29권5호
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• pp.617-624
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• 2005

An analysis of the effects of $CO_{2}$ on fundamental combustion characteristics was performed in Oxygen enriched condition by comparing the laminar burning velocities, flame structures, fuel oxidation paths. Fictitious $CO_{2}$ was introduced to discriminate the chemical reaction effects of $CO_{2}$ from the thermal effects. PREMIX code was utilized to evaluate the laminar burning velocities. OPPDIF code was utilized to investigate the flame structure and fuel oxidation path variation. The contributions of thermal effects on laminar burning velocities are dominant at lowly oxygen-enriched condition but those of chemical reaction effects become dominant at highly oxygen-enriched condition. Chemical reaction effects caused the additional flame temperature decrease besides thermal effects and oxygen-leakage increase in non-premixed flame. Specific fuel oxidation path and CO production path is enhanced in spite of overall decrement of fuel consumption rate by chemical reaction effects of$CO_{2}$.

• 한국포장학회지
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• 제21권1호
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• pp.1-10
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• 2015

Enzyme kinetics-based respiration model can be effectively used for estimating respiration rate in $O_2$ consumption and $CO_2$ production of fresh produce as a function of $O_2$ and $CO_2$ concentrations. Arrhenius equation can be applied to describe the temperature dependence of the respiration rate. Parameters of enzyme kinetics-based respiration model and activation energy of Arrhenius equation were compiled from analysis of literature data and closed system experiment. They enable to estimate the respiration rate for any modified atmosphere conditions at temperature of interest and thus can be used for design of modified atmosphere packaging of fresh produce.

• 한국미생물·생명공학회지
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• 제25권4호
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• pp.427-433
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• 1997

Sludge Returned CMAS process was applied to treat the wastewater from electric accessory manufacturing company while this type of wastewater was usually treated by chemical process. This result show that the removal rate of TCOD was about 70-80% regardless of hydraulic retention time, On the contrary, the removal rate of BOD was abtained in a range of 77-92% depending on hydraulic retention time. In order to remove more than 80% of organic materials with the proposed process, the F/M ratio should be maintained below 0.17. In this case, the calculated value of organic removal rate, Km, was calculated to be 1.26 hr$^{-1}$, and the ratio of cell synthesis/total energy was 0.32 and 0.26 for COD and BOD base, respectively. The yield coefficient was calculated to be 0.242 and the half velocity coefficient was 0.3 hr$^{-1}$. The value of endogenous respiration coefficient was 0.02 hr$^{-1}$. The measured effluent BOD concentration, MLSS concentration in aeration tank, oxygen uptake rate, and sludge production were matched relatively well with the calculated values using above coefficients, In order to optimize the dewatering of sludge, the hydraulic retention time was recommended to be 15. 6 hrs. These results indicate that the wastewater from an eletric accessory manufacturing company can be treated safely with a biological process.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.333-335
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• 2001

A simple control strategy of DO-stat was introduced to the recombinant rGuamerin production process in Pichia pastoris. This induction strategy consisted of two interrelated control loops ‘by which oxygen ratio of inlet gas and methanol feeding rate was controlled. Using this control strategy, over-feeding or under-feeding of methanol could be avoided in concomitance with the efficient control of dissolved oxygen level. As a result, the cell concentration reached 130 g/L and rGuamerin expression level was 450 iu/L, which was more than 40% increased result comparing with the fed-batch process using manual control of methanol feeding rate.

• 한국수산과학회지
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• 제43권6호
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• pp.679-686
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• 2010

To investigate the contribution of macroalgae to biogeochemical nutrients and carbon cycles, we measured the uptake rates of nutrients and $CO_2$ by Undaria pinnatifida using an incubation method in an acrylic chamber. From January to March 2010, U. pinnatifida was sampled at Ilkwang, a well-known area of macroalgae culture in Korea. The initial and final concentrations of nutrients, dissolved oxygen, total alkalinity, and pH of the chamber water were measured, and production/uptake rates were calculated using concentration changes, chamber volume, and incubation time. The production rate of dissolved oxygen by U. pinnatifida (n = 32) was about $5.4{\pm}4.0\;{\mu}mol\;g_{fw}^{-1\;}h^{-1}$. The uptake rate of total dissolved inorganic carbon (TDIC), calculated by total alkalinity and pH, was $7.9{\pm}6.5\;{\mu}mol\;g_{fw}^{-1}\;h^{-1}$. Nutrients uptake averaged $141.7{\pm}119.2$ nmol N $g_{fw}^{-1}\;h^{-1}$ and $15.0{\pm}9.1$ nmol P $g_{fw}^{-1}\;h^{-1}$. A positive linear correlation ($r^2$ = 9.6) existed between the production rate of dissolved oxygen and the uptake rate of total dissolved inorganic carbon, suggesting that these two factors serve as good indicators of U. pinnatifida photosynthesis. The relationships between fresh weight and uptake rates of nutrients and $CO_2$ suggested that younger specimens (<~50 g fresh weight) are much more efficient at nutrients and $CO_2$ uptake than are specimens >50 g. The amount of carbon uptake by the total biomass of U. pinnatifida in Korea during the year of 2008 was about 0.001-0.002% of global ocean carbon uptake. Thus, more research should be focused on macroalgae-based biogeochemical cycles to evaluate the roles and contributions of macroalgae to the global carbon cycle.

• Journal of Microbiology and Biotechnology
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• 제14권2호
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• pp.237-242
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• 2004

Cell growth and the production of pullulan by Aureobasidium pullulan HP-2001, the UV-induced mutant of A pullulans ATCC 42023, increased with increased concentration of glucose up to 15.0% (w/v). Maximal production of pullulan in the flask scale was 27.65 g/l, when concentrations of glucose and yeast extract were 15.0 and 0.25% (w/v), respectively. Maximal conversion rate of pullulan from glucose as the carbon source was 0.37, when those of glucose and yeast extract were 5.0 and 0.15% (w/v), respectively. On the basis of total amount of pullulan, the conversion rate of pullulan from glucose, and utilization rate of glucose to cell mass and pullulan by A. pullulans HP-2001, the optimal concentrations of glucose and yeast extract for the mass production of pullulan were determined to be 10.0 and 0.25% (w/v), respectively, at which concentrations the production of pullulan and its conversion rate were 27.14 g/l and 0.27, respectively. Maximal production of pullulan with optimized concentrations of carbon and nitrogen sources by A. pullulans HP-200l in a 7-1 bioreactor was 32.12 g/l for 72 h culture, and that in a 100-1 bioreactor with the inner pressure of $0.4 kgf/cm^2$ was 36.87 g/l. Increased inner pressure of a 100-1 bioreactor resulted in a higher concentration of dissolved oxygen in the medium, which might enhance the production of pullulan by A. pullulans HP-2001.

• Journal of Microbiology and Biotechnology
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• 제25권11호
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• pp.1819-1826
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• 2015

Poly(ε-ʟ-lysine) (ε-PL) is a novel bioactive polymer secreted by filamentous bacteria. Owing to lack of a genetic system for most ε-PL-producing strains, very little research on enhancing ε-PL biosynthesis by genetic manipulation has been reported. In this study, an effective genetic system was established via intergeneric conjugal transfer for Streptomyces albulus PD-1, a famous ε-PL-producing strain. Using the established genetic system, the Vitreoscilla hemoglobin (VHb) gene was integrated into the chromosome of S. albulus PD-1 to alleviate oxygen limitation and to enhance the biosynthesis of ε-PL in submerged fermentation. Ultimately, the production of ε-PL increased from 22.7 g/l to 34.2 g/l after fed-batch culture in a 5 L bioreactor. Determination of the oxygen uptake rate, transcriptional level of ε-PL synthetase gene, and ATP level unveiled that the expression of VHb in S. albulus PD-1 enhanced ε-PL biosynthesis by improving respiration and ATP supply. To the best of our knowledge, this is the first report on enhancing ε-PL production by chromosomal integration of the VHb gene in an ε-PL-producing strain, and it will open a new avenue for ε-PL production.

• 약학회지
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• 제51권1호
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• pp.75-82
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• 2007

Reactive oxygen species (ROS) are produced in the metabolic process of oxygen in cells. The superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in cells systemize the antioxidant enzymes to control the oxidative stress. Genistein is one of the isoflavonoids, and its role in controlling cellular oxidative stress is presently the active issue at question. In this study; we analyzed genistein-induced survival rates of the CHO-K1 cells, activities of antioxidant enzymes, ROS levels, and expression levels of antioxidant enzyme genes in order to investigate the effect of genistein on cellular ROS production and antioxidative systems in CHO-K1 cells. As results, the survival rate of cells was decreased as the dose of genistein increases (12.5${\sim}$200 ${\mu}$M). Genistein increased cellular ROS levels, while it reduced total SOD activities and the expression of CuZnSOD. In conclusion, we suggest that genistein may induce oxidative stress via down-regulation of SOD.

• Korean Chemical Engineering Research
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• 제56권5호
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• pp.647-654
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• 2018

지구 온난화 문제 해결과 온실가스 감축을 위하여 화력발전소를 중심으로 순산소 연소를 통한 $CO_2$ 포집 기술이 개발되었으나, 산소 생산 비용이 높아 경제성이 떨어지는 문제를 가지고 있다. 순산소 연소에 필요한 대량의 산소(>2,000 tpd)를 생산하는 방법은 초저온 공기분리장치(ASU: Air Separation Unit)가 가장 적합한 것으로 알려져 있으나, 대부분 고순도(>99.5%) 산소 생산에 최적화되어 건설되었다. 이런 초저온 공기분리장치에서 순산소 연소에서 사용이 가능한 낮은 순도(90~97%)의 산소를 생산하고 공정을 최적화할 경우, 공정 효율이 높아져 산소 생산 비용 절감이 가능하다. 본 연구에서는 순산소 연소 발전시스템에 산소를 공급할 수 있는 초대형(>2,000 tpd $O_2$) ASU 개발을 위하여 공정 분석 및 비교 평가를 수행하였다. 상용 프로그램인 AspenHysys를 이용하여 산소 순도에 따른 회수율 및 전력소모량을 계산하고 공정의 효율을 평가하였다. 그 결과 ASU를 통해 순산소 연소에 공급되는 산소는 약 95%가 최적이며, 생산 공정 최적화 시 약 12~18%의 전력소모량 절감이 가능한 것을 확인 할 수 있었다.