• Journal of the Mineralogical Society of Korea
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• 제9권1호
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• pp.1-6
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• 1996

Woolastonite from Susan occurs as intercalations in limestone beds of Lower Paleozoic Joseon Supergroup. It is a thermal metamorphic product of impure limestone. Electron microprobe analysis shows that it is considerably pure wollastonite. It has triclinic cell with a=7.932$\AA$, b=7.328$\AA$, c=7.069$\AA$, $\alpha$=89.995$^{\circ}$, $\beta$=$95.255^{\circ}$, and $ \Upsilon=103.367^{\circ}$.Dissolution behaviors of wollastonite have been studied conducting three different dissolution experiments; two different reactions with HC1 (one batch and one re-initialization experiment) and one traction with distilled water. In the batch type powder wollastonite-HCl reaction, pH of solution rapidly increases in the early stage and then its rate of increase slows down to reach plateau resulting in parabolic relationship with time. It is represented by the early rapid rise and fall in pH giving a sharp pH-edge and succeeding slow rise in the re-initialization experiment. The early rapid rise in pH is due to the rapid sorption of H- in solution to oxygens on the reactive surface of wollastonite and the fall in pH means that all reactive surface sites are occupied by H- ions and no more H- adsorption occurs. The slow rise in pH following the pH- edge is due to the dissolution of wollastonite as evidenced by the correlation of pH variation and cation concentration. Dissolution of powder wollastonite in HCl shows linear trend with time. Si is dissolved predominantly over Ca at a constant rate. Ca is dissolved predominantly in the very early stage. Dissolution rate of coarse-grained wollastonite fragments in distilled water is parabolic with times howing a rapid reaction in the early stage and a slow reaction in the advanced stage. The Ca/Si ratio in solution is high in the case of coarse-grained wollastonite fragment as compared with powder wollastonite. The coarse-grained wollastonite fragment-water (acid) reaction resulted in the solution with an elevated constant pH value (alkaline) giving an important significance on the environmental view point.

• Journal of Environmental Science International
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• 제27권3호
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• pp.219-225
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• 2018

This study was conducted to investigate the possibility of utilizing various types of nozzles and gas-liquid mixers to increase the dissolution rate of plasma gas containing ozone generated in a dielectric barrier plasma reactor. After selecting the air atomizing nozzle with the highest gas dissolution rate among the 13 types of test equipment, we investigated the influence of the operating factors on the air atomizing nozzle to determine the optimal plasma gas dissolution method. The gas dissolution rate was measured by a simple and indirect method, specifically, the measurement of KLa instead of direct measurement of ozone concentration, which requires a longer analysis time. The results showed that the KLa value of the simple mix of air and water was $0.372min^{-1}$, Which is 1.44 times higher than that ($0.258min^{-1}$) of gas emitted from a normal diffuser. Among the nozzles of the same type, the KLa value was highest for the nozzle having the smallest orifice diameter. Among the 13 types of devices tested, the nozzle with highest KLa value was the M22M nozzle, which is a gas-liquid spray nozzle. The relationship between water circulation flow rate and KLa value in the experimental range was linear. The air supply flow rate and KLa value showed a parabolic-type correlation, while the optimum air supply flow rate for the water circulation flow rate of 1.8 L / min is 1.38 times.

• Textile Coloration and Finishing
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• 제8권3호
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• pp.36-51
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• 1996

In order to investigate the degradation behavior of PET fabrics, sodium diethylene glycolate (SDEG)-diethylene glycol (DEG) solutions were prepared and PET fabrics were treated in the solution. The dissolution rate constant and apparent activation energy of the PET fabrics were calculated by Eyring's and Arrhenius's equation respectively and measured dyeing properties, moisture and antistatic properties. Then compared SDEG-treated fabrics with NaOH-treated. The results were as follows; 1. PET fabrics decreased their weight in SDEG-DEG solution, and the decreasing rate showed a linear relationship to the treating time at constant temperature and concentration of SDEG-DEG solution. 2. The dissolution rate constant showed a linear relationship to the concentration of SDEGDEG solution and an exponential relationship to treating temperature. 3. Apparent activation energy of dissolution was 23.45 kcal/mol. 4. The K/S values and the ΔL values of fabrics treated with SDEG-DEG solution are higher and lower respectively than fabrics treated with NaOH. 5. SDEG-DEG solution treatment improved fabric's moisture regain and it reached almost maximum at about 40% weight loss. 6. In the both reagent the light, wet and sublimation fastness of fabrics are similar. 7. SDEG-DEG solution gave more electrical discharge effect to the fabrics than that of NaOH. 8. NaOH treated PET microfiber have crater-like surface, while SDEG-DEG solution give bathochromic effect to the PET microfiber because which has wrinkles on the surface.

• Journal of Distribution Research
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• 제9권3호
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• pp.21-47
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• 2004

This study has investigated the effects of relieving and promoting factors on dissolution intention under the condition of low commitment buyer-seller relationships. Based on intensive literature reviews, eight alleviating factors (dependence, cooperation, communication, relational norms, transaction specific investments, relationship termination costs, satisfaction, and trust) and five promoting factors (opportunism, conflict, goal incongruity, attractiveness of alternatives, and unfairness) were included. A total of thirteen hypotheses were testee using data collected from a dining franchising system. Among 300 collected, 79 cases of low commitment buyer-seller relationships were analyzed. The results showed that eight out of thirteen hypotheses were supported. But five hypotheses related to the variables of cooperation, transaction specific investments, relationship termination costs, attractiveness of alternatives, and opportunism were not supported. following a detailed presentation of the analysis results, the paper concludes by discussing the academic and managerial implications of the findings.

• Journal of the Mineralogical Society of Korea
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• 제26권2호
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• pp.119-127
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• 2013

Borosilicate glass dissolution is an important chemical process that impacts the glass durability as nuclear waste form that may be used for high-level radioactive waste disposal. Experiments reported that the glass dissolution rates are strongly dependent on the bulk composition. Because some relationship exists between glass composition and molecular-structure distribution (e.g., non-bridging oxygen content of $SiO_4$ unit and averaged coordination number of B), the composition-dependent dissolution rates are attributed to the bulk structural changes corresponding to the compositional variation. We examined Na borosilicate glass structures by performing classical molecular dynamics (MD) simulations for four different chemical compositions ($xNa_2O{\cdot}B_2O_3{\cdot}ySiO_2$). Our MD simulations demonstrate that glass surfaces have significantly different chemical compositions and structures from the bulk glasses. Because glass surfaces forming an interface with solution are most likely the first dissolution-reaction occurring areas, the current MD result simply that composition-dependent glass dissolution behaviors should be understood by surface structural change upon the chemical composition change.

• YAKHAK HOEJI
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• 제33권4호
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• pp.229-236
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• 1989

Even though two different preparations are chemically equivalent, the variance of bioavailability differenciates the clinical effect of preparations, so that the preparations need to be evaluated by comparing bioavailability in vivo as well as chemical equivalence. In this study, bioequivalence tests of commercially available isoniazid tablets A, B, C and D (standard) were performed to give some guidelines to bioequivalence test. The bioavailability parameters obtained by drug administeration were statistically analyzed. Statistical evaluation of the data involved an analysis of variance for a cross over design. Cross over design was employed with 8 healthy volunteers. The results were within 20% difference of mean value in the AUC, Cmax, Tmax and amount of urinary excretion (Au) between standard and isoniazid tablets. The results of ANOVA showed no significant differences for 'group or sequence', but almost not for 'between subjects'. The tablet. A, B and D were within 20 min, but tablet C was within 50 min. Tablet A was biologically equivalent in the Au. tablet B biologically equivalent in the Au and AUC. Tablet C was biologically equivalent in the Au. The relationship between the dissolution rate and Au was significant.

• Korean Journal of Crystallography
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• 제11권4호
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• pp.224-230
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• 2000

We have been investigated the flaking mechanism of the soda-line glass. The pH of aqueous solution approached to 10 and increased with reaction time by ion exchange reaction between Na/sup +/ ion of glass and H/sup +/ ion of aqueous solution under the conditions of below pH 9 of start solution. The relationship between the pH of solution and reaction time shows logarithm. Total dissolution reaction of glass components by OH/sup -/ ion in aqueous seems to be dominant after the pH solution reached to 10 and the dissolution rate linearly increased with reaction time. The above tow reactions are simultaneously occurred. The dissolved Ca/sup 2+/ ions are reprecipitated on the glass surface to Ca-compound. The flakes are formed by the separation of leached layer of glass due to the different thermal expansion coefficient.

• Journal of Welding and Joining
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• 제34권6호
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• pp.55-61
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• 2016

Recently developed ferritic heat resistance steel, T24 was used to evaluate microstructure characteristics of simulated heat affected zone. Also, correlation between the prior austenite grain size and amount of $M_{23}C_6$ carbide dissolution was discussed. With the increasing of peak temperature, Grain size steadily increased up to $1050^{\circ}C$ and then rapidly increased at $1150^{\circ}C$. Of the peak temperature $950{\sim}1050^{\circ}C$, amounts of $M_{23}C_6$carbide dissolution are low. But Most of $M_{23}C_6$ carbide that is inhibited grain growth were dissolved above $1050^{\circ}C$ and decreased volume fraction of carbide. This indicates that grain growth may be achieved through dissolution of carbide in the base material. As of welding, due to very rapid heating rate, $M_{23}C_6$ carbide exists above equilibrium solution temperature that is $800^{\circ}C$, even at $1050^{\circ}C$. So, It was confirmed that close correlation between carbide dissolution in the base material and grain growth. Calculated grain size has a linear relationship with peak temperature, on the other hand, measured grain size discontinuously increased between $950{\sim}1050^{\circ}C$ and above $1050^{\circ}C$. Grain size of heat affected zone at $1350^{\circ}C$ peak temperature showed maximum 67um and minimum 4um. Also, The number of side showed 3 to 10.

• Journal of Pharmaceutical Investigation
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• 제39권2호
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• pp.97-106
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• 2009

Although lovastatin (LS) is widely used in the treatment of hypercholesterolemia, its bioavailability is known to be around 5%. This study was aimed to increase the solubility and dissolution-permeation rates of LS using solid dispersions (SDs) with bile salts. The solubilities of LS in water, aqueous bile salt solutions and non-aqueous vehicles were determined, and effects of bile salts on the cellulose or duodenal permeation of LS from SDs were evaluated using a horizontal permeation system. SDs were prepared at various ratios of LS to carriers, such as sodium deoxycholate (SDC), sodium glycocholate (SGC) and/or 2-hydroxypropyl-$\beta$-cyclodextrin (HPCD). The addition of bile salts (25 mM) in water increased markedly the solubility of LS by the micellar solubilization. Some non-aqueous vehicles were effective in solubilizing LS. From differential scanning calorimetric studies, it was found that the crystallinity of LS in SDs disappeared, indicating a formation of amorphous state. The SDs showed markedly enhanced dissolution compared with those of their physical mixtures (PMs) and drug alone. In the dissolution-permeation studies using a cellulose membrane, the donor and receptor solutions were maintained as a sink condition using pH 7.0 phosphate buffer containing 0.05% sodium lauryl sulfate (SLS). The flux of LS alone was nearly same as that of LS-SDC-HPCD (1:3:6) PM. However, the flux of LS-SDC-HPCD (1:3:6) SD slightly increased compared with drug alone and PM, suggesting that entrapment of LS in micelles does not significantly hinder the permeation across cellulose membrane. In the dissolution-duodenal permeation studies using a LS-HPCD-SDC (1:3:6) SD, the addition of various bile salts in donor solutions (25 mM) enhanced the permeation of LS markedly, and the fluxes were found to be $0.69{\pm}0.41$, $0.87{\pm}0.51$, $0.84{\pm}0.46$, $0.47{\pm}0.17$ and $0.68{\pm}0.32{\mu}g/cm^2/hr$ for sodium cholate (SC), SDC, SGC, sodium taurodeoxycholate (STDC) and sodium taurocholate (STC), respectively. The stepwise increase of donor SGC concentration increased the flux dose-dependently. From the relationship of donor SGC concentration and flux, the concentration of SGC initiating the permeation across the duodenal mucosa was calculated to be 11.1 mM, which is nearly same as the critical micelle concentration (CMC, 11.6 mM) of SGC. However, with no addition of bile salts and below CMC, the permeation was very limited and irratic, indicating that LS itself is very poor permeable. Higher protions of bile salt in SD such as LS-SDC or LS-SGC (1 : 49 and 1 : 69) showed highly promoted fluxes. In conclusion, SD systems with bile salts, which may form their micelles in intestinal fluids, might be a promising means for providing enhanced dissolution and intestinal permeation of practically insoluble and non-absorbable LS.

• Korean Journal of Materials Research
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• 제24권2호
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• pp.81-86
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• 2014

The nitrogen solubility and nitride capacity of $CaO-SiO_2-Al_2O_3-MgO-CaF_2$ slag systems were measured by using gas-liquid equilibration at 1773K. The nitrogen solubility of this slag system decreased with increasing CO partial pressure, with the linear relationship between nitrogen contents and oxygen partial pressure being -3/4. This system was expected to show two types of nitride solution behavior. First, the nitrogen solubility decreased to a minimum value and then increased with the increase of CaO contents. These mechanisms were explained by considering that nitrogen can dissolve into slags as "free nitride" at high basicities and as "incorporated nitride" within the network at low basicities. Also, the basicity of slag and nitride capacity were explained by using optical basicity. The nitrogen contents exhibited temperature dependence, showing an increase in nitrogen contents with increasing temperature.