• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.325-328
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• 2000

The effects of DO and pH on the mass production of pullulan with high-molecular weight from A. pullulans ATCC 42023 were evaluated. The maximum pullulan production yield (51%) was obtained at pH non control (initial pH 6.5) and DO control (above 50%) condition. The pullulan degrading enzyme was activated when the pH of broth reached lower than 5.0 and portion of low molecular weight pullulan was increased. The formation of a black pigment was observed at the initial stationary phase, 40hr of fermentation. Therefore, the fermentation should be carried out in pH non control and DO control condition and harvested before reaching stationary phase around 40h for the production of high molecular weight pullulan.

• 농업과학연구
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• 제45권3호
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• pp.419-427
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• 2018

The present study was conducted to investigate the effect of different levels of Korean corn grain on in vitro ruminal fermentation with total mixed ration (TMR) as a basal feed. Three ruminal cannulated Holstein steers (Body Weight $479{\pm}33.0kg$) were used as rumen fluid donors. Treatments for in vitro fermentation were TMR only (control, 3.0 g), TMR substituted partially with high level (HC, TMR 1.5 and corn 1.5 g), and with low level of Korean corn grain (LC, TMR 2.25 and corn 0.75 g), respectively. To measure in vitro ruminal pH, gas production, ammonia N and volatile fatty acids (VFA), the in vitro fermentation incubation was triplicated at $39^{\circ}C$, 120 rpm for 0, 1, 3, 6, 12, 24 and 48 h, respectively. Mean ruminal pH was significantly lower (p < 0.05) for HC than control. Changes in rumen pH was rather similar between the groups till 6 h after incubation, but the lowest pH for HC (pH 5.10) appeared at 48 h compared with control and LC. Total gas production was tended (p < 0.09) to be higher and ammonia N was significantly lower (p < 0.05) for HC than control and LC. Total VFA was higher (p < 0.05) for HC and LC than control but no differences appeared between HC and LC. Overall, the present data indicate that feeding different levels of Korean domestic corn grain may lead to high and sustainable starch degradation in the rumen.

• 한국재료학회지
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• 제10권6호
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• pp.445-449
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• 2000

가압 경수형 원자로 (pressurized light water reactor) 냉각재 계통 내의 주된 분식 생성물로 알려져 있는 nickel ferrite의 거동에 대해 고찰하기 위해 모의 nickel ferrite($Ni_{0.75}Fe_{2.25}O_4$)를 공침법으로 제조하였다. 수용액-pH-조절로는 am-monia 또는 potassium carbonate를, 공침물-세척제는 ammonia 수용액이나 potassium carbonate 수용액 또는 2차 증류수를 사용하였다. Nickel ferrite의 생성 및 수용액-pH-조절제와 공치물-세척제가 최종 생성물의 Ni-Fe 몰 비에 따른 수율 및 특성에 미치는 영향은 EDX, XPS, XRD 및 SEM으로 고찰하였다. 반응 전.후 Ni/Fe 몰 비에 따른 수율은, pH를 potassium carbon-ate로 조절한 후 2차 증류수로 공침물을 세척한 경우가 0.994로 가장 높이 나왔으며, pH-조절제로 potassium carbonate를 사용한 경우가 ammonia를 사용한 경우에 비해 높은 수율을 나타냈다. 이러한 차이는 공침 시에 수용액 내에서 ammonia가 보여주는 상대적으로 큰 $Na_{2+}{\leftarrow}NH_3$ 착화 효과와 더불어 공침물-세척제의 pH에 기인하는 것으로 해석하였다.

• 한국축산식품학회지
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• 제21권3호
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• pp.200-207
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• 2001

Effects of dietary chitosan on physico-chemical properties of pork were investigated. A total 24 pigs (55$\pm$5kg) were fed a control diet (a commercial feed) or chitosan-supplemented diets (T1: 0.2% chitosan, T2: 0.4% chitosan, T3: 0.6% chitosan) for 6 weeks. The 6 weeks later the initiated of the experiments, pigs were slaughtered and loins were collected from each treatment groups. The samples were stored at 0$\pm$1$^{\circ}C$ for 15 days. Ultimate pH tended to higher in the control than those in the treatments, and that of T3 was significantly lower than those of the others (P<0.05). Shear force and the total moisture contents were not significantly different between control and treatments and they decreased with storage days (P<0.05). Hunter L* values of control, T1 and T2 were significantly lower than that of T3 at 1 and 10 days (P<0.05). Hunter a* values of control were significantly higher than that of others at 1 and 5 days (P<0.05). Hunter b* values of control were significantly higher than that of others at 5 days (P<0.05).

• Journal of Biosystems Engineering
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• 제20권4호
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• pp.383-389
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• 1995

This study was conducted to develop an automatic nutrient control system for trickle application of nutrient solution. Temperature, electric conductivity(EC). pH and dissolved oxygen(DO) were selected as control variables. A controller using single-chip microcomputer was constructed. An automatic control system for nutrient solution and a controller using single-chip microcomputer with control algorithm were developed. The control system was tested, and could control temperature, EC and pH within the error ranges of $pm 0.2^{circ} pm 0.2mS/cm, pm 0.1pH$, respectively.

• Transactions on Control, Automation and Systems Engineering
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• 제2권2호
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• pp.130-135
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• 2000

A two parameter model of a single fictitious weak acid with unknown dissociation constant has been successfully applied to design a neutralization system for many multi-component acid streams. But there are some processes for which above two parameter model is not satisfactory due to poor approxmation of the nonlinearity of pH process. Here, for etter control of wide class of multi-component acid streams, a three parameter model of a strong acid and a weak acid with unknown dissociation constant is proposed. The model approximates effectively three types of largest gain variation nonlinearities. Based on this model a nonlinear pH control system is designed. Parameters can eeasily estimated since their combinations appear linearly in the model equations and nonlinear adaptive control system may also be constructed just as with the two parameter model.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1122-1126
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• 2009

The exogenously added cadaverine is effective in protecting Vibrio vulnificus from methyl viologen (MV)-induced superoxide stress at pH 8.5. Such a protective effect by cadaverine was not observed at pH 7.5. Consistently, the accumulated level of intracellular cadaverine at pH 8.5 is approximately four times as much as that of the control cell at pH 7.5. Cadaverine accumulation is not affected by MV. The protection of V. vulnificus by cadaverine from superoxide stress was abolished when cadB coding for the lysine-cadaverine antiporter was interrupted. However, the cadaverine-mediated protection was complemented with cadB DNA. Therefore, CadB of V. vulnificus not only acts as a lysine-cadaverine antiporter at acid pH to neutralize the external medium, but also mediates cadaverine uptake at alkaline pH to result in cell protection from superoxide stress.

• 한국환경과학회지
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• 제32권2호
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• pp.139-143
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• 2023

The effects of essential oils on pH, pathogens, and volatile fatty acids (VFA) in two poultry litters were investigated through a lab study. Essential oil-added poultry litters were randomly divided to two groups: control (200 g poultry litter) and Treatment (50 g thymol/Briefly, 200 g broiler litter was treated with or without 50 g thymol (Control and T1, respectively; 1 groups) and 200 g duck litter was treated with or without 50 g carvacrol (Control and T2, respectively; 2 group). Adding thymol to broiler litter increased the pH, reduced pathogens, and did not affect VFA. Interestingly, adding carvacrol slightly reduced the pH of duck litter, but had no significant effect on reducing pathogens and VFA. This difference is probably because the essential oil used and the properties of the two litters are different. In addition, pH was thought to control the odor generated from the litter, but this has not been proven. Further field studies should focus on clarifying this point.

• 한국물환경학회지
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• 제18권4호
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• pp.401-409
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• 2002

In this study, to evaluate the applicability of ORP and pH as process control parameters for an intermittent aeration process, a 200L/d bench-scale plant was installed and operated for 90 days. It was fed with synthetic wastewater which contained $COD_{Cr}$ : 400mg/L, TN : 40mg/L and TP : 7mg/L. ORP & pH were measured on-line and compared with the variation of nutrient concentrations. As the results, both of the ORP and pH were able to monitor successfully nitrification and denitrification. Bending-points on the ORP curve and peak points on the pH curve corresponded to the termination of nitrification and denitrification. For P uptake and release, pH was the best indicator for performance evaluation. The aerobic pH apex was appeared when P uptake was accomplished and there was a relationship between the P release and pH variation. But the pH curve needed filtering because there were many noises on it. In this study, the shape of the ORP & pH curves were varied as the operating conditions such as aeration rates and organic loads were changed. It allowed the operating states of biological systems to be effectively evaluated. If it is properly managed to show the bending points and peak points clearly, the on-line monitoring of ORP & pH will be a reliable and effective technique for process control of intermittent aeration processes.

• 한국유기농업학회지
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• 제25권4호
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• pp.901-916
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• 2017

6가지 천연 식물 추출물의 첨가가 반추동물의 메탄 감소에 대한 연구를 수행하였다. 반추위액은 cannula가 장착된 한우에서 채취하였으며, 공시축의 사양관리는 timothy와 농후사료 6:4 비율로 급여하였다. 50 ml serum bottle에 timothy 0.3 g, 반추위액 5 ml, McDougall's buffer 10 ml를 각각 넣고 인삼, 도라지, 유카식물, 동백나무, 차나무, 오갈피 추출물을 기질의 5%를 첨가한 뒤 발효시간대별(3, 6, 9, 12, 24, 48, 및 72시간) 7처리 3반복 수행하였다. pH는 6.55~7.41로 반추위 적정 pH 범위에 속하였다. 건물소화율은 첨가구에서 대조구에 비해 유의적(P<0.05)인 차이가 없었다. 총 가스 발생량은 발효 24시간대 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. 이산화탄소 발생량은 발효 9시간대, 메탄 발생량은 6시간대에서 첨가구와 대조구간 유의적(P<0.05)인 차이가 나타나지 않았다. 미생물성장량은 발효 12시간대 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였고, 발효 24시간대 인삼, 유카식물, 차나무, 오갈피 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. Total VFA 농도는 발효 12시간 차나무, 오갈피 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였고, 발효 48시간 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. Acetate 농도는 발효 24시간 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 감소하였고, propionate 농도는 발효 48시간 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. 결과적으로 6가지 천연식물 추출물의 첨가는 in vitro 반추위 발효성상에는 이상이 없었으나 메탄 감소의 효과는 나타나지 않았다. 추후 6가지 천연 식물 추출물의 농도를 달리하여 추가적인 시험이 필요할 것으로 사료 된다.