• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.481-487
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• 2009

In this of study, effects of input air velocity(0.05~0.22 m/sec) and molten carbonate salt temperature ($870{\sim}970^{\circ}C$) on flow regime transition have been studied by adopting a drift-flux model of air holdup and a stochastic analysis of differential pressure fluctuations in an air-molten sodium carbonate salt two-phase system(molten salt oxidation process). Air holdup where the flow regime transition begins was determined by air holdup-drift flux plot. The air holdup value which the flow regime transition begins was increased with increasing molten carbonate salt temperature due to the decrease of viscosity and surface tension of molten carbonate salt. To characterize the flow regime transition more quantitatively, differential pressure fluctuation signals have been analyzed by adopting the stochastic method such as phase space portraits and Kolmogorov entropy, The Kolmogorov entropy decreased with an increasing of molten carbonate salt temperature but increased gradually with an increase in an air velocity, however, it exhibited different tendency with the flow regime and the air velocity value which flow regime transition begins was same to the results of drift-flux analysis.

• Clean Technology
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• v.29 no.2
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• pp.95-101
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• 2023

An experiment was conducted to produce vaterite-type precipitated calcium carbonate from waste oyster shells in order to use them as recyclable resources. Calcined oyster shells containing calcium oxide as their main component were prepared at a temperature of 800℃ for 24 h. The oyster shells were dissolved in nitric acid or hydrochloric acid solution to make 0.1 M calcium nitrate or calcium chloride aqueous solution, and a carbonation reaction was performed using a 0.1 M sodium carbonate aqueous solution under various experimental conditions, which included varying the amount of aspatic acid additive, the amount of NH₄OH added, the reaction time, the reaction temperature, the stirring speed, and the type of dissolved acid. The XRD, SEM, and size distributions were analyzed and the vaterite content was calculated. Spherical precipitated calcium carbonate with a vaterite content of 95.9% was synthesized by adding 0.1 mol aspatic acid/1 mol CaO and 2 cm³ of NH₄OH, and reacting for 1 h at 25℃ while stirring at 600 rpm. The average particle diameter was found to be 12.11 ㎛. Calcium carbonate contatining high vaterite is used as high value added calcium carbonate for medical, food, inke additiver, etc.

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.218-230
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• 2016

The effect of steam explosion coupled with alkali (1% sodium hydroxide, 1% potassium hydroxide and 15% sodium carbonate) or organosolv solvent (85% methanol, 70% ethanol and dioxane) on the production of sugar, changes in the chemical composition of M. sinensis were evaluated. The steam explosion coupled with 1% potassium hydroxide and dioxane were better as compared with other treatments based on the removals of acid insoluble lignin, and about 89.0% and 85.4%. Enzymatic hydrolysis of steam explosion with 1% potassium hydroxide and dioxane treated M. sinensis, gave a 98.0% and 96.5% of glucose conversion, respectively. These results suggested that pretreatment of M. sinensis with either potassium hydroxide or dioxane could be a promising pretreatment method for glucose production.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.64-69
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• 1999

Slags are by-products of the metallurgical industry. The most important slag from the standpoint of the quantity used as building material is iron blastfurnace slag. Slags are either crystalline stable solid used as aggregates or glassy material used as hydraulic binder. Slag cements are low heat of hydration cements. Slags react more slowly with than portland cement but they can be activated chemically. Activatiors can be either alkaline activators such as soda, lime, sodium carbonate, sodium silicate or sulphate activators such as calcium sulphate or phosphogypsum. So, in this study slaked lime was used as an activator that the compressive strength of this modified cement(M1 type) is high range in early age. And initial setting time of M1 type cement was shorter than conventional cements.

• Journal of Ginseng Research
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• v.22 no.3
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• pp.205-210
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• 1998

Glucosidic bonds at the C20 position of the sapogenins were hydrolyzed easily in the lower pH, higher temperatures and longer times to give prosapogenins and sugars. The glucosidic bond of saponin at the C3 of ginsenoside-Rb1, which is secondary carbon, was relatively stable due to the low electron density of -0.2. But the bond of saponin at the C20 position, which is tertiary carbon with the relatively high electron density of -0.3, was liable to be hydrolyzed even in weakly acidic solution by the increase of heating time. On the other hand, red ginseng contained 13.34 mg/g of citric acid, 8.78 mg/g of malonic acid, 3.70 mg/g of oxalic acid, 2.13 mg/g of malic acid and 0.44 mg/g of succinct acid. Ginseng saponins were very stable in ginseng extract neutralized with sodium carbonate or sodium bicarbonate corresponding to the equivalent amount of the total organic acid in the red ginseng.

• Food Science of Animal Resources
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• v.30 no.5
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• pp.746-754
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• 2010

Response surface methodology was adopted to model and optimize the effects of microbial transglutaminase (TG) and calcium alginate (CA) systems of various ratios on the gelation characteristics of porcine myofibrillar protein (MP) at various salt levels. The CA system consisting of sodium alginate (SA), calcium carbonate (CC) and glucono-$\delta$-lactone (GdL) showed no remarkable changes in the salt-soluble fraction, and only minor effects on electrostatic interactions were observed. Increasing CA concentration caused acid-induced hydrophobic interactions in MPs, resulting in increased MP gel strength. The TG system, containing TG and sodium caseinate (SC), induced cold-set MP gelation by formation of covalent bonding. The main advantage of the combined system was a higher cooking yield when the MP gel was heated. These results indicated that 0.7% TG combined with 0.8% CA system can form a viscoelastic MP gel, regardless of salt levels.

• Journal of the Korean Society of Clothing and Textiles
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• v.9 no.3
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• pp.53-61
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• 1985

This paper has been studied on the method of washing without any damage on wool, namely foam washing method. Effect of washing was obtained with experimental equipment manufactured by way of trial. but some deflects were found that the volume of detergent solution and blow ratio changed with time passes by. This difficulties should be improved by farther studies. The solution mixed with sodium oleate ($0.5\%$) and sodium carbonate ($0.3\%$) was found suitable for detergent solution, and under the conditions of washing temperature at $50\~60^{\circ}C$ and washing time for 5 minutes, the washing effect was obtained good. Desoaping treatment with $Na_2CO_3$ solution after washing might be thought to be necessary, and from the scanning electron micrographs (SEM), no damage on wool and wool sureface washed was, observed. From the results of this study foam washing of wool may be expected to be very effective.

• Journal of Electrochemical Science and Technology
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• v.8 no.2
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• pp.146-154
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• 2017

In this study, copper (II) oxide was prepared for use in a copper electroplating solution. Copper chloride powder and copper (II) oxide are widely used as raw materials for electroplating. Copper (II) oxide was synthesized in this study using a two-step chemical reaction. Herein, we developed a method for the preparation of copper (II) oxide without the use of sintering. In the first step, copper carbonate was prepared without sintering, and then copper (II) oxide was synthesized without sintering using sodium hydroxide. The optimum amount of sodium hydroxide used for this process was 120 g and the optimum reaction temperature was $120^{\circ}C$ regardless of the starting material.

• Food Science of Animal Resources
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• v.29 no.5
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• pp.590-598
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• 2009

The aim of this study was to model and optimize the calcium alginate (CA) and microbial transglutaminase (TG) systems to form a cold-set myofibrillar protein (MP) gel containing 0.1 M or 0.3 M NaCl using a response surface methodology. The gel strengths of cold-set and heat-induced MP gels, and cooking yields were measured. All measured parameters showed determination coefficients ($R^2$) above 0.7 without a lack-of-fit. The CA system had the best results with component ratios of 1.0:0.3:1.0 corresponding to sodium alginate, calcium carbonate and glucono-$\delta$-lactone, respectively, and was favourable at 0.1 M NaCl. In contrast, the TG system only had an effect on cold-set MP gelation at 0.3 M salt, and the optimal ratio of TG to sodium caseinate was 0.6:0.5. By combining the two systems at 0.3 M NaCl, an acceptable cold-set MP gel with an improved texture and high cooking yield could be formed. Therefore, these results indicated that the functionality of the cold-set MP gel could be enhanced by combining these two optimized gelling system.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.18-24
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• 2013

The influences of various operating parameters on physico-chemical techniques were evaluated to remediate petroleum-contaminated sandy soil including S/L ratio, kinetic, and effect of soil particle size. The simple extraction using tap water removed only 20.6% of total petroleum hydrocarbon (TPH), and addition of NaOH enhanced the removal of TPH to approximately 30%. To meet the regulation levels, a surfactant, sodium dodecyl sulfate, was added, and the removal of TPH increased to 4 times. Probably, the carbonate minerals affected chemical aging and soprtion of petroleum, which inhibited the extraction of TPH. The soil with smaller particle size contained more TPH, and the removal of TPH was obstructed with smaller particle size. However, NaOH addition increased the removal of TPH in the smaller particles. The physico-chemical properties of soil influenced greatly the removal of petroleum even in sandy soil.