• 한국생물공학회:학술대회논문집
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• 2000.11a
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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.

• Korean Journal of Agricultural Science
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• v.45 no.3
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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.

• Korean Journal of Materials Research
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• v.10 no.6
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• pp.445-449
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• 2000

Nickel ferrite $(Ni_{0.75}Fe_{2.25}O_4$ was synthesized by co-precipitation method in order to investigate its behavior under conditions of the reactor coolant system in pressurized light water nuclear power plants. Ammonia or potassium carbonate was used as a solution pH control agent, and aqueous ammonia or potassium carbonate solution or secondary distilled water was used as a co-precipitate washing agent. The effects of the pH control agent and the co-precipitate washing agent on the production yield on the basis of the Ni/Fe molar ratio and the particle characteristics of final products were investigated by XRD, SEM, EDX and XPS. The production yield was almost congruent with that of the initial aqueous mixture in case of using potassium carbonate as a pH control agent, while in case of using ammonia, it was quite changed. The difference seemed to be due to the effects of $Ni^{2+}{\leftarrow}NH_3$complexation in the aqueous solution and of the pH of co-precipitate washing agent.

• Food Science of Animal Resources
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• v.21 no.3
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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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• v.20 no.4
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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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• v.2 no.2
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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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• v.19 no.10
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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.

• Journal of Environmental Science International
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• v.32 no.2
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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.

• Journal of Korean Society on Water Environment
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• v.18 no.4
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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.

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.901-916
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• 2017

This study was conducted to evaluate natural plant extracts for methane gas reduction in ruminants. Rumen fluid was collected from cannulated Hanwoo cow ($450{\pm}30kg$) consuming 400 g/kg concentrate and 600 g/kg timothy. The 15 ml of mixture comparing McDougall's buffer and rumen fluid in the ratio 2 to 1, was dispensed anaerobically into 50 ml serum bottles. Rumen fluid contents were collected and in vitro fermentation prepared control (timothy, 300 mg), ginseng, balloon flower, yucca plant, camellia, tea plant and ogapi extracts were added at the level of 5% against 300 mg of timothy as a substrate (v/w) and incubated for 3, 6, 9, 12, 24, 48, and 72 h. In vitro pH values range 6.55~7.41, this range include rumen titration. The dry matter digestibility was not differ between all treatments and control. Total gas emission was significantly higher (p<0.05) in ginseng and balloon flower treatments on 24 h than in control. Carbon dioxide emission was not differ all treatments on 9 h than in control and significantly higher (p<0.05) yucca plant, camellia and tea plant treatments on 12 h than control. Methane emission was not differ all treatments on 6 h than in control. The rumen microbial growth rate was significantly higher (p<0.05) in ginseng, balloon flower on 12 h and significantly higher (p<0.05) in ginseng, yucca plant, tea plant and ogapi treatments on 24 h than in control. Total VFA was significantly higher (p<0.05) in tea plant and ogapi treatments on 12 h than in control and significantly higher (p<0.05) in ginseng, balloon flower treatments on 48 h than in control. Acetic acid was significantly lower (p<0.05) in ginseng and balloon flower treatments on 24 h than in control. Propionic acid was significantly higher (p<0.05) in ginseng and balloon flower treatments on 48 h than in control. As a results, sixth natural plant extracts had no significant effect dry matter digestibility and negative on rumen fermentation, but not effect methane reduction.