• Korean Journal of Plant Resources
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• v.24 no.5
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• pp.499-506
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• 2011

The purpose of this study was to search available resources for new natural colorants. The extraction efficiency of colorants from black cowpea seed coats and their storage stability were examined according to the various extraction and storage conditions in this study. The results obtained were as follows: the optical density (O.D.) values of the extracted colorants increased with increasing extract time and temperature. Extraction at pH 4 was seen to be the most efficient among the various pH conditions. The color of the extract solutions were seen to change with variation in pH, for example, anthocyanins display color changes from orange-red, to orange, to blue, to greenish-blue at pH 3.0, 4.0-6.0, 7.0 and 9.0-11.0, respectively. The color changes of the extract solutions over various storage periods were determined using UV/Vis spectra these color changes indicate characteristic absorption patterns and a discoloration index which indicates the rate of absorbance (532 nm/454 nm). Methionine addition influenced the storage stability of the colorant solutions and this addition led to better storage stability than non-addition. In paper chromatography of juice extracted colorant, a long stripe was seen on development. Among three colorants obtained via paper chromatography according to development rate, at least two different colorants were mixed indicated by the appearance, or not, of a shoulder at 552 nm depending on the extent of development.

• 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.

• YAKHAK HOEJI
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• v.6 no.1
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• pp.5-7
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• 1962

Like the condensation reaction of general aldehyde, that of benzaldehyde with semicarbazide also depends upon the concentration of carbonium ion that is produced by hydrogen ion. The lower pH value is the facility of the formation of carbonium ion in the condensation reaction, while the reactivity of semicarbazide as a reactant is reduced. In this paper, therefore we want to find out the optimum pH value in the condensation reaction of benzaldehyde with semicarbazide. This optimum pH value was determined by using the simple paper-chromatographic method. According to the result of this experiment, the condensation reaction between benzaldehyde and semicarbazide reacts with its highest point at 3.5pH value. It seems clear that at this point the benzaldehyde acquires the most suitable amount of carbonium ion for the condensation reaction with semicarbazide, and the semicarbazide also has the optimum reactivity.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.6
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• pp.15-20
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• 2012

The effects of sulfur dioxide on paper were investigated since these sulfur compounds could cause damages on cellulose and organic materials in papers. For the reason, exposure ageing tests were performed on traditional Korean paper (Hanji) and two different types of modern paper (acid-free and acid paper) to determine the damage with regard to the optical as well as physicochemical properties according to the varying $SO_2$ concentration. As a result, optical properties were not changed while physical and chemical peoperties were remarkably changed with the exposure period. In the case of pH, $SO_2$ had little impact on the pH of the Hanji and acid-free paper while the pH of acid paper was remarkably decreased. The decrease of the folding endurance of the Hanji was relatively smaller than those of the acid-free and acid paper. The results prove Hanji was more resistant to $SO_2$ than the modern paper in terms of optical, physical and chemical properties. In addition, it was also suggested that $SO_2$ concentration should be kept below 0.01 ppm for the preservation of paper objects.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.218-222
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• 1984

Browning pattern was developed in aqueous solutions of glucose/glycine mixture under controlled conditions. Browning pattern was definitely influenced by pH of medium and concentration of reactants. Filter paper disks were immersed in diluted solutions of glucose/glycine system and fried in cooking oil. Concentrations of reactants only affected browning pattern of fried filter paper disks and pH effect was obscured at high temperatures. Amorphous brown precipitate was obtained from the lowest pH medium of glucose/glycine system. An attempt was made to characterize the brown pigment produced in the present model system.

• Journal of Sensor Science and Technology
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• v.20 no.4
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• pp.234-237
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• 2011

This paper presents a study into pH Indicator-Embedded hydrogel micro-particles which are encoded various shapes according to the captured indicator. We incorporate various pH indicators into a photo-curable hydrogel, PEG-DA(Poly(ethylene glycol) diacrylate). Using the latest fluidic lithography techniques, we can easily fabricate variously patterned hydrogel particles based on in-situ photopolymerization of the PEG-DA in a micro-fluidic channel. The shape of the particle is related to the pH indicator inside the particle. We demonstrate that the micro pH sensors change their colors according to the pH levels. The micro pH sensors have various characteristics that are related to the curing time, particle size, etc. By changing these conditions, we can adjust the long term stability and reaction time of the hybrid micro pH sensors.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.1-6
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• 2003

This paper reports on a pilot scale comparison of PACS coagulation with and without pH preadjustment. The pH of the water was adjusted with carbon dioxide and sulfuric acid. Process performance was assessed on the basis of total organic carbon(TOC), UV absorbance, turbidity and disinfection by-product(DBP) precursors. Coagulation pH appeared to be a determining factor for maximum NOM removal. The optimum coagulation pH in order to decrease TOC and turbidity were pH 7. Preadjustment of pH 7 increased TOC removal to as much as 43, 47 percent with sulfuric acid and carbon dioxide. Moreover, coagulation at pH 7 caused a reduction in UV$_{254}$, THMFP and HAAFP compared to the baseline coagulation. For preadjustment of pH 7 with carbon dioxide, the percentage of TOC, UV$_{254}$, THMFP and HAAFP shows the reduction rate of 3.8, 0.5, 4.8, 9.4％ comparing to the coagulation rendition using sulfuric acid. Acid addition to depress pH during coagulation decrease Langelier Saturation Index(LSI), potentially causing increase corrosion in water distribution systems. LSI for carbon dioxide and sulfuric acid at pH 6 was -2.3, -3.3. Therefore, carbon dioxide was more effective at controlling corrosion than sulfuric acid.

• Journal of applied mathematics & informatics
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• v.40 no.5_6
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• pp.873-882
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• 2022

In this paper, we construct the multiple (h, p, q)-Hurwitz-Euler eta function by generalizing the multiple Hurwitz-Euler eta function. We get some explicit formulas and properties of the higher-order (h, p, q)-Euler numbers and polynomials.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.2
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• pp.26-33
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• 2009

A new testing method to evaluate the deposition potential of white pitch was developed. The new method involves depositing the potential white pitch particles on the air bubble covered plastic film in the pitch deposit tester (PDT) developed by KRICT and analysing the deposited area of white pitch using an image analyzer. In addition, the effect of two important factors (pH and calcium hardness) on white pitch deposition potential was elucidated. When pH of the coated broke stock was increased from neutral to alkali or the calcium hardness of the stock was decreased, the pitch deposit area was decreased, implying that these two factors have to be controlled during the evaluation of pitch deposition potential. It was found that hydrophobicity of the surface of latex binding films repulped is a key factor influencing white pitch deposition.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.4
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• pp.59-65
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• 2008

Electrochemical properties of pulp fiber could be modified by LbL(Layer-by-Layer) multilayering. Salt concentration and pH affect the conformation and ionization degree of polyelectrolyte. In this study, therefore, we intended to evaluate the effect of pH and salt concentration in polyelectrolyte multilayering on the electrochemical properties of pulp fiber. The pH of the stock was varied to 4, 7, and 10. Salt concentration was controlled at 0.001, 0.003, and 0.005 M of NaCl. Higher zeta potential was obtained when pulp fibers were multilayered at the condition of higher pH and higher salt concentration. The final zeta potential of pulp fiber after multilayering was dependent on the adsorption ratio of polyelectrolyte and the initial zeta potential of fibers.