• 한국전기화학회:학술대회논문집
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• 2004.10a
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• pp.11-11
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• 2004

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.1
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• pp.23-30
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• 1994

The objective of this study was to analyze the effect of the dissolution of detergent on washing and rinsing efficiency, and the possibility of saving detergent in washing. Washing and rinsing efficiency were reviewed in three different ways : A method was to input dissolved detergent by the use of rapid detergent dissolution instrument, B method was to input dissolved detergent beforehand, and C method was to input undissolved detergent. The results were as follows 1. A method > B method > C method was shown in detergency with washing time and three method's gaps were reduced because detergent dissolution effect was reduced by mechanical action in proportion of washing time. Especially, according to detergency of A method of 0.07% and C method of 0.1% was appeared approximately, saving detergent was expected by rapid dissolution of detergent. 2. A method > B method > C method was shown in detergency with washing temperature. As the washing temperature rose, the detergent reached chemically more activated state and become easily soluble. It resulted for the detergent to penetrate and adhere to laundry easily. 3. A method > B method > C method was shown in detergency with detergent concentration and C method was more sensitive than A, B method against change of detergent cocentration. Rapid detergent dissolution made it possible not only to enhance the washing efficiency but also to save the detergent because detergency of A method in low concentration is higher than that of C method. 4. A method $\geq$ B method > C method was shown in rinsing ratio with detergent input method. It indicated input dissolved detergent was advantageous in rinsing. 5. The result of anion surfactant concentration test of each process with detergent input method was shown like that A method In B method > C method in washing and reverse result was shown in rinsing. The anion surfactant concentration of C method was low during washing but high during rinsing. This was identical with previous results which shown the washing and rinsing efficiency improved with dissolved detergent usasge. 6. C method > B method > A method was shown in the degree of remaining detergent after rinsing. There was no remaining detergent after second rinsing in A and B method, but in C method four rinsings were required for the same result. Consequently, in A and B methods, less water and electricity were used, and less abrasion of cloth.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.635-641
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• 2002

Electrical conduction of $SrZrO_3$ doped with $Y_2O_3$ was measured as a function of gas atmosphere and temperature by impedance spectroscopy. Hydrogen dissolution, due to an enhanced driving force in the presence of oxygen, results in protonation by water incorporation. Proton conductivity increased with water vapor pressure, ${P_w}^{1/2}$. In the pure hydrogen atmosphere, the dissolution of hydrogen,$H_2(g)=2H_{i}$ +2e', is supposed to be driven by a reduced activity of electrons, ascribable to their trapping in oxygen vacancies. The activation energy of electrical conductivity was 50 kJ/mol, in wet argon atmosphere in the temperature range of $600~900^{\circ}C$, similar to those reported for proton conduction in the literature. Grain boundary effect in proton conduction was substantial in the 10% doped case at temperatures lower than $700^{\circ}C$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.187-196
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• 2021

Chemical equilibrium calculations for multicomponent aqueous systems involving the reductive dissolution of magnetite (Fe₃O₄) with oxalic acid (H₂C₂O₄) were performed using the HSC Chemistry® version 9. They were conducted with an aqueous solution model based on the Pitzer's approach of one molality aqueous solution. The change in the amounts and activity coefficients of species and ions involved in the reactions as well as the solution pH at equilibrium was calculated while changing the amounts of raw materials (Fe₃O₄ and H₂C₂O₄) and the system temperature from 25℃ to 125℃. In particular, the conditions under which Fe₃O₄ is completely dissolved at high temperatures were determined by varying the raw amount of H₂C₂O₄ and the temperature for a given raw amount of Fe₃O₄ fed into the aqueous solution. When the raw amount of H₂C₂O₄ added was small for a given raw amount of Fe₃O₄, no undissolved Fe₃O₄ was present in the solution and the pH of the solution increased significantly. The formation of ferrous oxalate complex (FeC₂O₄) was observed. The equilibrium amount of FeC₂O₄ decreased as the raw amount of H₂C₂O₄ increased.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.61-71
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• 1992

Through the low-temperature(60-150${\circ}C$) hydrothermal treatment of perlite with the alkaline solution at various NaOH concentrations, the mode of volcanic glass alteration and resultant zeolite formation were investigated in a closed system. At a temperature of 80${\circ}C$ and alkalinities of pH range 8 to 12, corresponding to the natural environments of diagenetic zeolite formation, only weak dissolution of perlitic glass occurs without zeolite formation despite the residence time of 100 days. Activities of Si and Al increase progressively, as a consequence of increasing pH, whereas activity ratios of Si/Al decrease. Zeolites were synthesized from perlite in the alkaline solution at above 0.1M NaOH concentrations. Below the temperature of 100${\circ}C$ Na-P was mainly formed, whereas analcime was the dominant zeolite at the temperature range of 100-150${\circ}C$. During Na-P synthesis chabazite and Na-X were also formed as by-products in case of lower proportion of solution/sample(<10ml/g) and higher NaOH concentraion (>3M), respectively. The alteration modes of perlite in the zeolite synthesis reflect that the formation of synthetic zeolites occurs as an incongruent dissolution likely with the diagenetic formation of natural zeolites from volcanic glass. Considering much difference in reaction kinetics between natural and synthetic systems, however, the evaluated synthetic conditions in these experiments were not directly applicable to the natural diagenetic system.

• Archives of Pharmacal Research
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• v.24 no.6
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• pp.568-571
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• 2001

The purpose of this work was to study the effect of storage time and temperature on the in vitro release kinetics of a commercial sustained-release dosage form of theophylline, at different pHs of the dissolution medium. The formulation was stored at $35^{\circ}C$ for 16 months and at $45^{\circ}C$ for 8 months, with a relative humidity of 60%. The in vitro release tests were performed at pHs 2, 4, 6 and 7.4. The mean values of the transport coefficient n, were close to 0.5 in all the conditions tested, which indicates that the transport system is not modified after storage of the formulation at $35^{\circ}C$ and $45^{\circ}C$. The mean values of the dissolution rate constant ranged from 0.036 to 0.043 $min^{-n}$, under all the conditions tested. Significant differences (${\alpha}=0.05$) were found between pHs 2, 4 and 6, 7.4 for all the model-independent parameters studied. When the formulation was kept at $35^{\circ}C$ for 16 months, the mean percentage of drug dissolved at 8 hours was 25.61% (pHs 2, 4) and, 36.12% (pHs 6, 7.4), representing a 26% and 24% reduction, respectively. Simitar results were obtained after storing the formulation at $45^{\circ}C$ for 8 months, corresponding to 33.3% (pHs 2, 4) and, 22.5% (pHs 6, 7.4) diminution, respectively. The values of the similarity factory $f_2$, obtained were lower than 50, which indicates the lack of similarity among the dissolution profiles, after storing the formulation under the experimental Conditions tested.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.1
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• pp.43-50
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• 2000

In this study, experiments were carried out to measure the variations in the corrosion potential and current density of polarization curves using polycarbonate. The results were particularly examined to identify the influences affecting the corrosion potential including various conditions such as temperature, pH, catalytic enzyme, and salt. The lines representing the active anodic dissolution were only slightly shifted in the potential direction by temperature, pH, enzyme, and salt. The tafel slope for the anodic dissolution was determined based on the polarization effect with various conditions. The slope of the polarization curves describing the active-to-passive transition region were noticeably shifted in direction. Also, from the variation in the conditions, the optimum conditions were established for the most rapid transformation, including temperature, pH, corrosion rate, and resistance of corrosion potential. The second anodic current density peak and maximum passive current density were designated as the critical corrosion sensitivity(Ir/If). The value of Ir/If was then used in measuring the extent of the critical corrosion sensitivity of the polycarbonate. The potentiodynamic parameters of the corrosion were obtained using a Tafel plot.

• Journal of the Korean Society for Heat Treatment
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• v.24 no.5
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• pp.262-270
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• 2011

Carbide precipitation and dissolution behavior at various temperatures during heat treatment has been studied in STD11 cold working die steel through confocal scanning laser microscopy; dilatometry; and X-ray diffraction analysis. The equilibrium phase diagram and phase fractions with temperature were calculated using a FactSage program. Confocal laser microscopic observation revealed that ${\alpha}$ to ${\gamma}$ transformation temperature is near $800^{\circ}C$; M7C3 carbides melt at $1245^{\circ}C$; and the melting temperature of STD11 is near $1370^{\circ}C$. XRD results indicated that the M23C6 carbides dissolve in the matrix if austenitized at over $1030^{\circ}C$; while the M7C3 carbides remain up to $1200^{\circ}C$ although their amount decreases. The calculated equilibrium phase diagram showed good agreement with experimental results on carbide dissolution and phase transformation temperatures.

• Korean Journal of Metals and Materials
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• v.49 no.12
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• pp.917-923
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• 2011

Dissolution and precipitation behaviors of complex carbonitrides in austenite of a V-Nb microalloyed steel were quantitatively examined through electrical resistivity measurement and transmission electron microscopy. The electrical resistivity increased with solution treatment temperature up to $1240^{\circ}C$ and then was saturated at $225n{\Omega}m$ for a holding time of 10 min. The electrical resistivity method was also used to quantitatively measure the isothermal precipitation kinetics of the complex carbonitrides in austenite. Nb-rich precipitates were observed in austenite at the early stages of precipitation, but Nb was replaced by V up to the equilibrium amount within the precipitates with further holding time. The time-temperature-precipitation diagram showed a C-type curve; nose temperature and its incubation time were $900^{\circ}C$ and 100 s, respectively.

• Journal of the Mineralogical Society of Korea
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• v.27 no.1
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• pp.53-62
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• 2014

In order to remove Fe impurity from low-grade pyrophyllite ore, the effect of certain variables such as particle size, concentration of sulfuric acid, amount of ammonium sulfate, added hydrogen peroxide, and temperature were studied. The euhedral cubic pyrites were observed in the low-grade pyrophyllite ore by reflected light microscopy, and quartz and dickite were identified in the sample by XRD analysis. The results of the Fe removal experiments showed that the best Fe removal parameters were when the particle size was at -325 mesh, the addition of $H_2SO_4$, $(NH_4)_2SO_4$ and $H_2O_2$ was at a 2.0 M, 10.0 g/l, and 3.0 M concentration, respectively, and at a $70^{\circ}C$ leaching temperature. In the dissolution kinetics analysis, the dissolution of Fe from the pyrite surface was a controlled chemical reaction, and the Fe dissolution reaction was proportioned to 0.066/R, $[H_2SO_4]^{1.156}$, $[(NH_4)_2SO_4]^{0.745}$, $[H_2O_2]^{0.428}$.