• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.10
• /
• pp.1525-1530
• /
• 2015

Doenjang made with various concentrations of salt solution such as 13, 14, 15, 16, 17, and 18% for making low-salt Doenjang. Physicochemical and sensory characteristics of Doenjang made with various concentrations of salt solution were analyzed. As a result, salt contents of Doenjang made with various concentrations of salt solution were 6.09~13.47%. Amino-type nitrogen showed a higher value when prepared with lower salt solution. The pH value increased with lower concentration of salt solution, whereas total acidity decreased with lower concentration of salt solution. The pH values and total acidity of Doenjang made with more than 16% salt solution were not statistically different. The reducing sugar content ranged from 1.39~6.30 mg/g, and higher salt content was associated with higher reducing sugar content. In the sensory descriptive analysis, Doenjang had the most salty taste at a salt concentration of 18%, whereas Doenjang at concentrations of 15%, 16%, and 17% did not show any statistical differences. In the consumer acceptance test, Doenjang made with 17% and 18% salt solution showed the highest score, followed by Doenjang made with 15% and 16% salt solution. In conclusion, the salty taste of Doenjang made with 16% salt solution might be used to make low-salt Doenjang. However, consumer acceptance of these Doenjangs was lower than that of Doenjang made with 17% and 18% salt solution.

• Journal of Korean Society of Water and Wastewater
• /
• v.14 no.4
• /
• pp.343-349
• /
• 2000

Techniques such as dissolved air flotation and electroflotation, which utilize micro bubbles, are increasingly used for water and wastewater treatment. Most studies have concentrated on particle characteristics. Pretreatments that manipulate particle size and zeta potential were considered important. A recent study, which modeled the collision mechanism between micro bubbles and particles in dissolved air flotation, suggested bubble characteristics should also be important. Hydrogen micro bubbles were generated electrolytically and their zeta potentials measured under various conditions using a novel electrophoresis method. Effects of several parameters were investigated. Bubble zeta potentials were found to be pH dependent, and to have a negative value around neutral pH, becoming zero or positive at lower pH. The pH at zero zeta potential was 5.0 under study conditions. Using artificial solution and tap water, at fixed pH, bubble zeta potentials varied with solution composition. Zeta potentia]s of bubbles were affected by the types of cations and anions in solution but not by the voltage applied. These findings will help improve efficiencies of particle removal processes that utilize micro bubbles. As bubble zeta potential varies with solution composition, it needs to be measured for each composition to understand those effects, which increase removal efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05b
• /
• pp.132-136
• /
• 2002

In this paper, aging characteristics of outdoor silicone rubber insulator resulting from the acid rain have been investigated with regards to nitrate ion $({NO_{3}}^{-1})$. For this purpose, silicone rubber was aged by immersing into the nitric solutions with different level pH during 1500 hours and various tests (tracking, $tan{\delta}$, breakdown voltage, SEM, EDS, contact angle) were performed. It was observed that the degradation was increased to pH 2.5 slightly and at pH 1.5 highly. And thus, it could be expected that there is certain critical point between pH 1.5 and 2.5, which leads to throught degradation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.09a
• /
• pp.28-33
• /
• 2001

In this paper, aging characteristics of outdoor silicone rubber insulator resulting from the acid rain have been investigated with regards to nitrate ion ($NO^{-1}_{3}$ ). For this purpose, silicone rubber was aged by immersing into the nitric solutions with different level pH during 1500 hours and various tests (tracking, tan $\delta$, breakdown voltage, SEM, EDS, contact angle) were performed. It was observed that the degradation was increased to pH 2.5 slightly and at pH 1.5 highly. And thus, it could be expected that there is certain critical point between pH 1.5 and 2.5, which leads to throught degradation.

• Journal of Power System Engineering
• /
• v.20 no.1
• /
• pp.42-49
• /
• 2016

This study showed that on-site ferrate(VI) solution was synthesized by wet oxidation method and applied aqueous 2,4-dichlorophenol(DCP) solution to evaluate the degradation efficiency. On-site ferrate(VI) solution was synthesized by putting $FeCl_3{\cdot}6H_2O$ in the strong alkali solution with NaClO and NaOH and applied DCP solution directly. DCP solution was extracted by the liquid-liquid method and analyzed by GC-ECD. The factors such as pH, DCP initial concentration, injected ferrate(VI) dosage, temperature were investigated. The optimum pH and temperature conditions of DCP degradation were obtained in neutral condition and $35^{\circ}C$. And the experimental results showed that DCP removal efficiency also increased with the decrease of DCP initial condition and the injected ferrate(VI) dosage.

• Restorative Dentistry and Endodontics
• /
• v.29 no.3
• /
• pp.249-266
• /
• 2004

The purpose of this study was to determine whether pH and time has any influence on the degradation behavior of composite restoration by analyzing the leached monomers of dental composites qualitatively and quantitatively after storage in acetate buffer solution as a function of time using high performance liquid chromatography (HPLC) / mass spectrometer. Materials and Methods：Three commercial composite restorative resin materials (Z-250, Heliomolar and Aeliteflo) with different matrix structure and filler composition were studied. Thirty specimens (7mm $diameter{\times}2mm$ thick) of each material were prepared. The cured materials were stored in acetate buffer solution at different pH (4, 7) for 1, 7 and 45days. As a reference, samples of unpolymerized composite materials of each product were treated with methanol (10mg/ml). Identification of the various compounds was achieved by comparison of their mass spectra with those of reference compound, with literature data. and by their fragmentation patterns. Data were analysed statistically using ANOVA and Duncan's test. Results：1. Amounts of leached TEGDMA in Aeliteflo were significantly larger than those of UDMA in Z-250 and Heliomolar at experimental conditions of different storage time and pH variation (p<0.001). 2. As to comparison of the amounts of leached monomers per sorage time, amounts of leached TEGDMA in Aeliteflo and UDMA in Z-250 and Heliomolar were increased in the pH 4 solution more significantly than in the pH 7 solution after 1day, 7days and 45days, respectively (p<0.001). 3. In total amounts of all the leached monomers with storage times, the overall amounts of pH 4 extracts were larger than those of pH 7 extracts for all resin groups, but there was no significant difference (p>0.05).

• Korean Journal of Poultry Science
• /
• v.17 no.2
• /
• pp.109-114
• /
• 1990

Enzymatic activity of isolated Lysozyme from egg white by cation ion-exchange chromatography was detected with various methods and stability of lysozyme in solution was studied by heat and pH treatments. Lysozyme activity refered to mg pure lysozyme/mg sample was more accurate although it needed standard lysozyme. But lysozyme activity refered to units/mg sample could be detected easily and reducted total detection time. Enzymatic activity of isolated lysozyme which dissolved in 0.066M phosphate buffer(pH 6.3) and then incubated at $37^{\circ}C$ for 2hr was increased remarkably on the lysis of Micrococcus lysodeikticus. The activity of isolated lysozyme by CM Sephadex C-25 was higher in eluting solution of above O. D. 1.0 at 640nm and attained 36, 000 units/mg solid. The stability of isolated lysozyme was decreased by various heat treatment. Activity began to decrease above 6$0^{\circ}C$ and dropped rapidly at $100^{\circ}C$. Especially, 35% loss of activity occured in 0.066M phosphate buffer at $100^{\circ}C$. for 15min. The stability of lysozyme was also affected by pH. lysozyme was very stable in acidic solution but in alkaline solution. Enzymatic activity showed maximum value at pH 3.0 solution while decreased rapidly above pH 6.0 solution.

• Resources Recycling
• /
• v.27 no.4
• /
• pp.44-49
• /
• 2018

$MoO{_4}^{2-}$ is the stable chemical species of Mo(VI) in alkaline solution. In the pH range of 2 to 6, condensation polymerization between $MoO{_4}^{2-}$ and hydrogen ion results in the formation of various polyanions of Mo(VI). Polycations of Mo(VI) begin to form when solution pH is less than 2. As the concentration of inorganic acid increases, polycations of Mo(VI) can react with the anion of the inorganic acid, resulting in the formation of heteranions of Mo(VI). The distribution of Mo(VI) species at pH < 6 depends on the concentration of Mo(V) and inorganic acid. In order to analyze the solvent extraction and ion exchange data on Mo(VI) from concentrated inorganic acid solution, it is necessary to elucidate the nature of Mo(VI) complexes.

• Korean Journal of Plant Resources
• /
• v.18 no.3
• /
• pp.417-423
• /
• 2005

In order to investigate effects of dyeing conditions on the dyeing characteristics in silk during natural dyeing using indigo plants , various dyeing conditions including the temperature of dyeing solution, dyeing period, the concentration and pH of dyeing solution and mordants were treated. As the temperature of dyeing solution decreases low, the color of silk surface showed lower b value. The color of silk surface showed G line when the dyeing solution was $-5^{\circ}C$ and room temperature and GY line at more than $40^{\circ}C$. Coloring degree increased high as the temperature increases. Dyeing period showed no effect on the surface color, but as dyeing period was longer the coloring degree increased. When the concentration of dyeing solution was $1\~4\%$, the silk was colored to BG line and $5\%$ to B line. The coloring degree increased as the concentration of dyeing solution more increased. The pH of dyeing solution sensitively affected coloring of silk. The pH lower than 7 showed G line, pH 8 showed GY line and pH 9 showed YR line. Coloring degree decreased as pH was more increases. Surface color of silk was different according to the kinds of natural mordants and coloring degree was increased by the natural mordants.

• Nuclear Engineering and Technology
• /
• v.52 no.11
• /
• pp.2543-2551
• /
• 2020

Calculations of chemical equilibrium for multicomponent aqueous systems of the HyBRID dissolution of magnetite were performed by using the HSC Chemistry. They were done by using a Pitzer-based aqueous solution model with the recipe of raw materials in experiments conducted at KAERI. The change in the amounts of species and ions and the pH values of the solution at equilibrium was observed as functions of temperature and raw amount of CuSO₄. Precipitation of Cu₂O occurred at a large amount of CuSO₄ added to the solution, while no precipitation of Cu(OH)₂ was found at any amounts of CuSO₄. The E-pH diagrams for Cu were constructed at various Cu concentrations to provide the effect of the Cu concentration on the pH values at boundaries where the coexistence of Cu⁺ ion and Cu₂O solid occurred. To prevent Cu⁺ ions from being precipitated to Cu₂O, the raw amount of CuSO₄ should be adjusted so that the pH value of the solution from the equilibrium calculation is less than that from the E-pH diagram. We provided guidelines for the raw amount of CuSO₄ and the pH value of the solution, which prevent the formation of Cu₂O precipitates in the HyBRID dissolution experiments for magnetite.