• Journal of Microbiology and Biotechnology
• /
• 제22권12호
• /
• pp.1673-1680
• /
• 2012

In this study, DEAE-corncobs [delignified corncob grits derivatized with 2-(diethylamino)ethyl chloride hydrochloride ($DEAE{\cdot}HCl$)] were prepared as a carrier to immobilize yeast (Saccharomyces cerevisiae) for ethanol production. The immobilized yeast cell reactor produced ethanol under optimized $DEAE{\cdot}HCl$ derivatization and adsorption conditions between yeast cells and the DEAE-corncobs. When delignified corncob grit (3.0 g) was derivatized with 0.5M $DEAE{\cdot}HCl$, the yeast cell suspension ($OD_{600}$ = 3.0) was adsorbed at >90% of the initial cell $OD_{600}$. This amount of adsorbed yeast cells was estimated to be 5.36 mg-dry cells/g-DEAE corncobs. The $Q_{max}$ (the maximum cell adsorption by the carrier) of the DEAE-corncobs was estimated to be 25.1 (mg/g), based on a Languir model biosorption isotherm experiment. When we conducted a batch culture with medium recycling using the immobilized yeast cells, the yeast cells on DEAE-corncobs produced ethanol gradually, according to glucose consumption, without cells detaching from the DEAE-corncobs. We observed under electron microscopy that the yeast cells grew on the surface and in the holes of the DEAE-corncobs. In a future study, DEAE-corncobs and the immobilized yeast cell reactor system will contribute to bioethanol production from biomass hydrolysates.

• 대한기계학회논문집A
• /
• 제35권9호
• /
• pp.1137-1143
• /
• 2011

초고온가스로의 중간열교환기는 원자로에서 생산된 $950^{circ}C$ 정도의 초고온 열을 수소생산 공장으로 전달하는 핵심 기기이다. 한국원자력연구원에서는 중간열교환기의 후보 형태로 고려되고 있는 인쇄기판형 열교환기의 소형 시제품을 제작하였다. 본 연구는 소형가스루프 시험조건하에서 인쇄기판형 열교환기 소형 시제품의 고온 구조건전성을 시험수행 전에 미리 평가하기 위한 작업의 일환으로 인쇄기판형 열교환기 소형 시제품에 대한 고온 구조해석 모델링, 거시적 열 해석 및 구조 해석을 수행하고 그 결과들을 정리한 것이다. 해석 결과는 곧 수행될 인쇄기판형 열교환기 소형 시제품 성능시험결과와 비교하고 또한 향후 제작될 중형 시제품 설계/제작에 반영할 것이다.

• Nuclear Engineering and Technology
• /
• 제54권7호
• /
• pp.2491-2509
• /
• 2022

As an important device in the nuclear island, the nuclear coolant pump can continuously provide power for medium circulation. The vane is one of the stationary parts in the nuclear coolant pump, which is installed between the impeller and the casing. The shape of the vane plays a significant role in the pump's overall performance and stability which are the important indicators during the safety serve process. Hence, the bionic concept is firstly applied into the design process of the vane to improve the performance of the nuclear coolant pump. Taking the scaled high-performance hydraulic model (on a scale of 1:2.5) of the coolant pump as the reference, a united bionic design approach is proposed for the unique structure of the guide vane of the nuclear coolant pump. Then, a new optimization design platform is established to output the optimal bionic vane. Finally, the comparative results and the corresponding mechanism are analyzed. The conclusions can be gotten as: (1) four parameters are introduced to configure the shape of the bionic blade, the significance of each parameter is herein demonstrated; (2) the optimal bionic vane is successfully obtained by the optimization design platform, the efficiency performance and the head performance of which can be improved by 1.6% and 1.27% respectively; (3) when compared to the original vane, the optimized bionic vane can improve the inner flow characteristics, namely, it can reduce the flow loss and decrease the pressure pulsation amplitude; (4) through the mechanism analysis, it can be found out that the bionic structure can induce the spanwise velocity and the vortices, which can reduce drag and suppress the boundary layer separation.

• 한국미생물·생명공학회지
• /
• 제27권1호
• /
• pp.46-53
• /
• 1999

The purpose of this study was to optimize the conditions of continuous mixed culture of C.butyricum and R. spaeroides K-7, which were able to produce hydrogen using biomass-dreived substrate. To investigate the possibility of continuous culture, semi-continuous culture was carried out for 20 days. In semi-continuous culture using the reactor system, the replacement rate of fresh medium was 30% of total medium volume for the highest hydrogen evolution. In continuous culture, the optimum dilution rate was determined to be 0.05$h^{-1}$. The continuous culture produced 3.1 times as compared with the hydrogen on batch culture. On the other hand, the continuous mixed culture produced 1.3~2.1 times as much as hydrogen of the continuous monoculture of C. butyricum. When 10g of glucose in the media (1l) was supplied as a carbon source on continuous culture, mixed culture of C. butyricum and R. sphaeroides K-7 increased hydrogen evolution rate. Because considerable amount of glutamate was contained in waste water of glutamate fermentation, utilization of glutamate was examined in mixed culture. As a result of examination, production of hydorgen was slightly inhibited by high concentration of glutamate, more than 20mM, on continuous monoculture of R. sphaeroides K-7. On the other hand, both on continuous monoculture of C. butyricum and on mixed culture of C. butyricum and R. sphaeroides K-7, production of hydrogen was not inhibited by high concentration of glutamate such as 100mM. Hence this suggests that high concentration of waste water can be used as good substrate for hydrogen production on monoculture of C. butyricum and mixed culture of C. butyricum and R. sphaeroides K-7.

• Applied Biological Chemistry
• /
• 제38권1호
• /
• pp.26-30
• /
• 1995

돼지감자 분말을 원료로 alginate에 고정화된 Kluyveromyces marxianus FO43의 에탄올 생산성을 향상시키기 위한 연구를 수행하였다. 15% 돼지감자 배지에서 발효시킨 고정화 효모에 의한 에탄올 농도와 이론치에 대한 에탄올 수율은 4일 후에 각각 3.38%(w/v), 54.20%로 이것은 고정화하지 않은 효모의 3.76%(w/v), 71.13% 보다 낮았다. Cellulase의 첨가는 $15{\sim}20%$ 돼지감자 배지의 점조성을 크게 낮추어 고정화 효모의 에탄올 생산성을 증가시켰다. 그리하여 20% 배지에서도 효소를 처리하여 고정화 효모를 4일 발효 시키면 에탄올 농도를 5.57%(w/v), 이론치에 대한 에탄올 수율을 68.86%까지 얻을 수 있었다. Repeated batch culture를 실시한 결과 bead의 활성이 22일 동안 저하되지 않고 유지되었다.

• 한국해양바이오학회지
• /
• 제1권4호
• /
• pp.292-297
• /
• 2006

오염된 양식 해수의 수질정화능력이 뛰어난 광합성세균의 고순도 대량배양을 위한 실험을 실험실 단위 및 파이롯트 단위에서 수행했다. Gas pack 반응기, flask 반응기 및 N-source로서 질소 가스를 사용한 실험 결과, 광합성세균은 현미경상 약 90%이상의 순도를 나타내었고, CFU 측정 결과에서도 붉은색을 띄는 광합성세균 colony만을 관찰 할 수 있었다. 배지의 교차에 의한 배양실험에서 기초배지를 이용한 배양이 광합성세균의 성장에 가장 효과적임을 알 수 있었다. 이러한 배양조건하에서의 5L bioreactor 배양에서 비증식속도가 $0.18h^{-1}$로 나타났고, 실험실 단위의 결과를 이용한 pilot 단위에서의 배양결과, 실험실 단위의 비증식속도와 동일한 값을 얻을 수 있었다.

• 한국축산식품학회지
• /
• 제44권2호
• /
• pp.372-389
• /
• 2024

This study investigated the efficacy of ultraviolet-C (UV-C) irradiation in enhancing the quality of raw bovine milk by targeting microbial populations and lipid peroxidation, both of which are key factors in milk spoilage. We categorized the raw milk samples into three groups based on initial bacterial load: low (<3 Log 10 CFU/mL), medium (3-4 Log 10 CFU/mL), and high (>4 Log 10 CFU/mL). Using a 144 W thin-film UV-C reactor, we treated the milk with a flow rate of 3 L/min. We measured the bacterial count including standard plate count, coliform count, coagulase-negative staphylococci count, and lactic acid bacteria count and lipid peroxidation (via thiobarbituric acid reactive substances assay) pre- and post-treatment. Our results show that UV-C treatment significantly reduced bacterial counts, with the most notable reductions observed in high and medium initial load samples (>4 and 3-4 Log 10 CFU/mL, respectively). The treatment was particularly effective against coliforms, showing higher reduction efficiency compared to coagulase-negative staphylococci and lactic acid bacteria. Notably, lipid peroxidation in UV-C treated milk was significantly lower than in pasteurized or untreated milk, even after 72 hours. These findings demonstrate the potential of UV-C irradiation as a pre-treatment method for raw milk, offering substantial reduction in microbial content and prevention of lipid peroxidation, thereby enhancing milk quality.

• Nuclear Engineering and Technology
• /
• 제41권2호
• /
• pp.187-198
• /
• 2009

In this paper, three power ramp tests performed on high burn-up Re-crystallized Zircaloy2 - UO2 BWR fuel rods (56 to 63 MWd/kgU) within the SCIP project are simulated with METEOR and ALCYONE 3D. Two of the ramp tests are of staircase type up to Linear Heat Rates of 420 and 520 W/cm and with long holding periods. Failure of the 420 W/cm fuel rod was observed after 40 minutes. The third ramp test consisted of a more standard ramp test with a constant power rate of 80 W/cm/min up to 410 W/cm with a short holding time. The tests were first simulated with the METEOR 1D fuel rod code, which gave accurate results in terms of profilometry and fission gas releases. The behaviour of a fuel pellet fragment and of the cladding piece on top of it was then investigated with ALCYONE 3D. The size and the main characteristics of the ridges after base irradiation and power ramp testing were recovered. Finally, the failure criteria validated for PWR conditions and fuel rods with low-to-medium burn-ups were used to analyze the failure probability of the KKL rodlets during ramp testing.

• KSBB Journal
• /
• 제8권5호
• /
• pp.478-482
• /
• 1993

LSM을 이용하여 KA112 균주의 고농도 배양을 시도하였다. Separator로는 hollow fiber를 사용하였고 reactor로는 Celligen을 이용하였다. Wroking volume 1리터로 10일간 배양하여 최고 세포농도가 회분식 배양에 비하여 10배 이상 증가한 $2.1\times10^7$ cells/ml이었고, 항체의 농도는 4.5배 정도 높았다. 최고 feed rate에서 항체생산속도는 회분식 배양보 다 9배 높았으며 배양 중 glucose농도가 Ig/e 이상일 때 specific productivity가 증가하였고, 1 g/6 이하얼 때 세포성장은 영향을 받지 않으냐 spe­c cific prodictivity는 감소하였다.

• 한국미생물·생명공학회지
• /
• 제21권4호
• /
• pp.373-380
• /
• 1993

When the cells of yeast K35 were immobilized in Ca-alginate gel, cell concentration and viability decreased as alginate concentration increased. Considering the results, 2% (w/v) Ca-alginate concentration would be suitable. Among various concentrations of additives and cross-lin-king agent, the addition of 1.67% (w/v) of bentonite together with 0.33% (v/v) of glutaraldehyde (ABG bead) resulted in the highest ethanol production of 1.8%(w/v), using YPD medium containing 2% glucose. ABG bead seemed to be more resistant to phosphate ion than Ca-alginate bead. 0.33%(w/v) of phosphate was a proper concentration for the ethanol production by ABG bead. Scanning electron microscopic observation depicted that the immobilized cells on the bead surface were coated by alginate gel and that the cells in the internal bead were cross-linked with alginate matrix. When repeated-batch culture was performed with ABG bead for 40 days in a packed-bed reactor, ethanol concentration of about 90~110 g/l-gel was maintained. Cell viability was maintained around 70%, and outgrowing cell concentration was below 6.3% of total cell concentration. Consequently, the results showed that ABG head was a potential carrier for continuous production of ethanol compared to conventional Ca-alginate bead.