• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.382-386
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• 1998

The objectives of this study are to reveal relationship between tree physiology and spectral reflectance on effects of artificial acid rain and to obtain basic data on optimal wave length for forest of LRC sensor on KOMPSAT-2. Three pH levels of artificial acid rain - control, pH4.5 and pH3.0 - were applied to Pinus and Quercus species. Three types of the acid rain were spraied at the amount of 500m1 in every two days. Spectral reflectance data was collected once in a month by using GER 1500 (350~2500nm) or Ll 1800(300~1100nm) Spectroradiometer. The data was measured three times in a pH level. The results of this study are as follows; in April, the spectral reflectance of Pinus species was high in order at the level of pH3.0, control and pH4.5; in May, control, pH3.0 and pH4.5; in June, control, pH4.5 and pH3.0. That of Quercus species was high in the order of control, pH4.5 and pH3.0 in May; in June, control, pH3.0 and pH4.5, especially, within infrared wave length range, control, pH4.5 and ph3.0.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.457-460
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• 1996

An adaptive pH control is developed to manipulate the nonlinearities and time-varying properties of pH systems. In this research, we estimate two adjustable parameters by using the recursive least squares method and a nonlinear PI controller is used to control pH systems based on the estimated two parameters.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.145-151
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• 1996

The effectiveness of physiological or chemical acid - alkali solution was investigated as the method to control pH value of nutrient solution in hydroponics dynamically. Lettuces were cultivated using NH$_4$H$_2$PO$_4$ as physiological acid and NaNO$_3$ as physiological alkali or H$_2$SO$_4$ as chemical acid in dynamic control system. The pH of nutrient solution was controlled satisfactorily in the range of pH 5.5-6.5, regardless of treatments. Chemical acid changed pH of solution faster than chemical acid when supplied to the nutrient solution. Any of them did not show any harmful symptom. It is recommended that chemical acid is preferred during the growing stage and physiological acid like as NH$_4$H$_2$PO$_4$ is preferred from several days before harvest stage.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.215-223
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• 2006

The internal corrosion of water distribution systems is the main cause for the problem of the public health threat as well as water leakage in the damaged pipeline, red water, and odor and taste of the tap water. This study was examined the effect of chemicals used for pH and alkalinity control and corrosion inhibitors for producing the optimal corrosion control method. Corrosion study at different pH and alkalinity indicated that these control using alkaline chemicals was effective in corrosion rate, Fe release reduction, but examined to be increased in turbidity and corrosion-by-products(TTHMs) problems. The turbidity was slightly increased, requiring caution in controlling corrosion with $Ca(OH)_2$. At pH 9.0, TTHMs concentration is increased two times corn pared with non-control of pH. Using the pipe which had experienced 28 years of exposure, iron release was decreased with the corrosion inhibitor. Consequently, pH, Alkalinity control method using alkaline chemicals must be complemented by corrosion inhibitor application for efficient corrosion control.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.17-22
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• 2013

In this study, a pH control method by carbon dioxide ($CO_2$) was applied to coagulation process in water treatment plant (WTP) to investigate the coagulation efficiency and residual dissolved aluminum when high pH raw water is flowing into the plant during algal blooming. Existing coagulant dose (1 mg/L in raw water) resulted in the pH reduction of 0.0384 by LAS, 0.0254 by PAC, 0.0201 by A-PAC, and 0.0135 by PACS2, respectively. And then the concentration of dissolved aluminum was 0.02 mg/L at pH 7.44, 0.07 mg/L at pH 7.96, 0.12 mg/L at pH 8.16, 0.39 mg/L at pH 8.38 showing the concentration increase with pH in the coagulation process. It was noteworthy that rapid increase was observed at pH above 8.0 next the rapid mixing. Therefore it is necessarily required to control pH below 7.8 in the coagulation process in order to meet drinking water quality standard of aluminum for high pH raw water into WTP, $CO_2$ injection could control pH successfully at about 7.3 even for the raw water of high pH above 8.0. In addition it was found that the pH control by $CO_2$ injection was significantly effective for coagulation in terms of turbidity removal, coagulant dosage, and residual dissolved aluminum concentration.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.476-481
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• 1988

In this paper a pH process of a weak acid with a strong base is modeled into a bilinear form, and a self-tuning pH control algorithm which is robust against initial values of solution and disturbances is presented. The control algorithm employs the recursive least square method for the parameter estimation and the generalised minimum variance criterion as the objective function. The computer simulation shows that the tracking of desired pH values is obtained in satisfactory manner regardless of the initial values chosen for the process.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.551-554
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• 2003

This study was carried out to investigate the effects of the pH of irrigation water on the growth, yield, and grain quality of rice. It acquire fundamental knowledges to set up irrigation water quality standards. The pot experiment was conducted with 5 treatments using irrigation waters with various pH values(control, 4, 6, 8, 10) and replicated four times with randomized block design. The results of this study showed that the uptake of N, P, and K, Ripened grain ratio and yield of rice tended to be reduced at the irrigation water of pH 4 and pH 10. P uptake, Ripened grain ratio and yield of rice at pH 4 water were significantly lower than the control. K uptake at pH 10 water was significantly lower than the control. Plant height, SPAD value and protein content of rice were not affected by the pH of irrigation water.

• Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.177-181
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• 2012

To understand the effects of lower pH levels due to elevated $CO_2$ and salinity, we designed and constructed a pH-control system that included automatic $CO_2$ infusion and measured the hatching rate of a crustacean model species, Artemia franciscana. The pH-control system was cost-effective and capable of performing animal tests in which pH fluctuated around $8.0{\pm}0.1$, with the temperature around $27{\pm}0.5^{\circ}C$. Hatching rate was observed under four different pH levels (7.0, 7.3, 7.6, and untreated control) combined with three salinity ranges (15, 25, and 35 ppt). The results demonstrated that lower pH levels led to decreased hatching rates regardless of salinity, and the minimum hatching rate was detected at pH 7.0 compared to the control (pH $8.0{\pm}0.1$), supporting the idea that OA has adverse effects on hatching rates and increases the risk of juveniles being introduced in the ecosystem. In contrast, salinity changes exhibited no synergistic effects with pH and had independent effects.

• Journal of Bio-Environment Control
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• v.4 no.2
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• pp.203-210
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• 1995

Using the programmable logic controller (PLC), a kind of microcomputer, a facility to control EC and pH automatically in nutriculture of tomato was developed. A program for the automatic control of nutriculture was written in ladder diagram language. EC and pH levels of nutrition solution could be maintained at 1.70-1.72 and 6.1-6.5, respectively, during the entire growing period. Better fruits and higher yield were obtained in automatic control plot than in the control plot. Inorganic elements in plant were higher in the former than in the latter.

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.4
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• pp.357-365
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• 2020

The aim of present study was to investigate regulatory mechanism of alpha-linolenic acid (ALA) during in vitro maturation (IVM) on nuclear and cytoplasmic maturation of porcine oocytes. Basically, immature cumulus-oocyte complexes (COCs) were incubated for 22 h in IVM-I to which hormone was added, and then further incubated for 22 h in IVM-II without hormone. As a result, relative cumulus expansion was increased at 22 h after IVM and it was enhanced by treatment of ALA compared with control group (p < 0.05). During IVM process within 22 h, cAMP level in oocytes was decreased at 6 h (p < 0.05) and it was recovered at 12 h in ALA-treated group, while oocytes in control group recovered cAMP level at 22 h. In cumulus cells, it was reduced in all time point (p < 0.05) and ALA did not affect. Treatment of ALA enhanced metaphase-I (MI) and MII population of oocytes compared with oocytes in control group at 22 and 44 h, respectively (p < 0.05). Intracellular GSH levels in ALA group was increased at 22 and 44 h after IVM (p < 0.05), whereas it was increased in control group at 44 h after IVM (p < 0.05). In particular, the GSH in ALA-treated oocytes during 22 h of IVM was higher than control group at 22 h (p < 0.05). Lipid amount in oocytes from ALA group was higher than control group (p < 0.05). Treatment of ALA did not influence to absorption of glucose from medium. Cleavage and blastocyst formation of ALA-treated oocytes were enhanced compared with control group (p < 0.05). These findings suggest that supplementation of ALA could improve oocyte maturation and development competence through increasing GSH synthesis, lipid storage, and regulation of cAMP accumulation during early 22 h of IVM, and these might be mediated by cumulus expansion.