• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2301-2307
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• 2015

The aim of this study was to evaluate the feasibility of application of the high voltage impulse (HVI) technique to the control of scale formation by calcium carbonate, which is pointed out as an important issue in industrial water treatment. The HVI system consisted of the power supply, high voltage generator, capacitors, switch and impulse generator was designed and made in laboratory scale, which can make 17kV impulse. HVI was introduced to the reactor that was filled with synthetic water containing $Ca^{2+}$ion. The concentration of calcium ion decreased only 3.0% after 5 minutes of contact time. However, it decreased up to 13.7% after 60 minutes of HVI contact time. Temperature and pH increased but conductivity decreased due to precipitation of the calcium carbonate. Although the decrease in concentration of calcium ion was not sufficient, it was verified that the HVI technique could be applicable for the softening and desalting processes.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.726-730
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• 2019

The removal of calcium ions using zeolite to solve problems of the CaCO₃ manufacturing process using cement kiln dust was investigated. To do so, a modified zeolite was employed and experiments were conducted to select the optimal zeolite type considered the binding cation and structure, evaluate the removal performance of calcium ions, the influence of the type and concentration of the modifying solution, and the removal selectivity when K coexists. Among five zeolites, 13X zeolite was found to have the best calcium ion removal performance, and it was confirmed that the removal performance was enhanced when KCl was used as a modifying solution instead of NaCl. This study is expected to be the basis for the solution of carbonation process and high concentration of KCl recovery technology.

• Resources Recycling
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• v.12 no.4
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• pp.38-43
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• 2003

Phosphate is an essential material for the growth of organisms. However. since relatively small amount is required. a large amount of phosphate is abandoned in wastes and wastewater. which contaminate the ecological environment including aquatic system. Purpose of this study is to treat especially high concentrated phosphate wastewater by use of calcium precipitation method. The pH range considered was from 6 to 12 and the maximum removal of phosphate was attained at pH 12. The con-centration of phosphate was observed to decrease rapidly until a half amount of calcium ion to its equivalent for the formation of calcium phosphate precipitate was added. which resulted in the decrease of the remaining concentration of phosphate down to 0.0027 mM. The effect of fluoride ion was examined and the concentration ratio between the phosphate and fluoride ion did not have any significant influence on the removal efficiency of phosphate. The effect of pH was also investigated. With the increasing of the pH in solution, the removal rate of phosphate was increased. Also it was investigated that the effect of fluoride on the phosphate removal was not significant.

• Food Science and Preservation
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• v.11 no.4
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• pp.472-477
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• 2004

This study was carried out to investigate the effect of liquid calcium(LC) on the quality of kimchi during fermentation. LC retarded the decreasing rate of pH and the increasing rate of titratable acidity during fermentation at $10^{\circ}C$, and the effect was more conspicuous at $7.0\%(v/w)$ than at $3.5\%(v/w)$ in each LC type. Microbial counts of total and lactic acid bacteria were lower in LC added kimchi than control before 8 days but higher in LC added kimhi after 8 days. Changes in color of a value were gradually increased, but L and b value were decreased. Calcium content of added LC on kimchi; A concentration $3.5\%(v/w),\;7.0\%(v/w)$ were $103{\sim}110\;mg\%,\;145{\sim}163\;mg\%$ and B concentration $3.5\%,\;7.0\%$ were $140{\sim}151\;mg\%,\;210{\sim}220\;mg\%$.

• Journal of Nutrition and Health
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• v.34 no.5
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• pp.532-540
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• 2001

This study explored the effect of calcium levels and/or ovariectomy on bone composition and its related factors using the female Sprague-Dawley rats which achieved peak bone mass in normal(0.5%) calcium intake during growth period. The rats were randomly divided into six groups and fed 0.1%, 0.5% and 1.5% calcium diets for 8 weeks after ovariectomized and sham operation. The results indicated that body weight gain was higher in ovariectomized groups than sham groups, regardless of dietary calcium levels and food intakes. Serum Ca and P concentrations were normal level regardless of dietary calcium levels and operation. Estrogen concentration was decreased in ovariectomized rat groups. Serum alkaline phosphatase activity and urinary hydroxyproline were increased in ovariectomized groups. When rats were fed normal Ca diet during growing period, weight, length and breaking force of femur were not significantly different in all groups but increased the same level. Generally, lipid contents in lumbar and femur were lower in low calcium groups and this effect was more pronounced in femur. In case of femur, the significant decrease in Ca contents of bone was observed in a relatively short period of feeding low Ca diet, even though it appeared th desirable peak bone mass had achieved through the growing period by supplementing the adequate amount of calcium. The marked decrease of estrogen levels after ovariectomy did not seem to influence greatly bone parameters measured except bone wet weight. Therefore, this study indicated that lower intake of Ca might be more important determinating factor against osteoporosis than postmenopausal state stimulated by ovariectomy in female rats. With normal or high intake of Ca it appears possible to prevent bone loss in postmenopausal period, and this might apply only in case of achieving peak bone mass in the growing with the adequate intake of calcium. (Korean J Nutrition 34(5) : 532∼540, 2001)

• Journal of the Korean Society of Clothing and Textiles
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• v.5 no.1
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• pp.9-14
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• 1981

The influence of laundering conditions on calcium deposition on the fabric was studied by repeated laundering the cotton fabric with soap in the hard water of 200 P.P.M. $CaCO_3$. The experimental variables were: 1) soap concentrations ($0.06\%$, $0.13\%$, $0.25\%$), 2) water contents in the fabric after hydroextraction. ($65\%$, $150\%$, $315\%$), 3) builders (Na-EDTA, sodium carbonate, sodium metasilicate), 4) washing cycle (5, 10, 15, 20 cycles). The fabric was washed for 15 minutes at $23\pm1^{\circ}C$ in a washing machine (Model; Gold Star Wp-2005) under the similar conditions with those of home laundering, and rinsed 5 times for 5 minutes. The amount of calcium deposits on the fabric was determined by the EDTA-Back titration method described by Wasserman and Basch. Results of this study were follows: 1) The amount of calcium deposits on the fabric increased with increasing wash cycles. 2) During the rinsing process, residual calcium content on the fabric increased with water content in the fabric after hydroextraction. 3) The amount of calcium deposits on the fabric decreased with the increasing soap concentration above the equivalent amount of calcium ion content in the water. 4) Sequestering agents and alkaline builders influenced the amount of calcium deposits on the fabric. The amount of calcium deposits on the fabric was in the order of sodium metasilicate, sodium carbonate, nonbuilder, and EDTA.

• Korean Journal of Community Nutrition
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• v.5 no.2
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• pp.273-279
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• 2000

This study was carried out to evaluate the calcium and phosphorus intakes and correlation with growth performance of 25male breast and formula-fed infants from 1 to 3 months postpartum. There were four groups breast-fed(BF) and three formula-fed groups(FFM, FFN and FFP). There was no significant difference in the height and weight of infants according to feeding methods and formula brands. Milk intake and the concentration of calcium and phosphorus from human milk and the formulas were measured. The average calcium content of human milk was 26.6$\pm$4.1mg/dl and 13.5$\pm$2.0mg/dl, respectively. The average calcium intakes of the brest-fed and formula-fed infants were 205.5$\pm$29.3mg/day and the 460.5$\pm$70.6mg/day, respectively the average calcium intake of breast-fed infants was significantly lower than that of formula fed infant. The percent of RDA(41%) of breast-fed infants was lower than that(75.4%) of formula fed infant. The average phosphorus intake of the brest-fed and formula-fed infants were 105.1$\pm$20.1mg/day and 288.3$\pm$37.3mg/day, respectively. The precent of RDA(27%) for brest fed was significantly lower than that(75.4%) of formula fed. The Ca/P ratios were 2.1 in brest fed and 1.6 in formula fed infant. The average calcium and phosphorus intakes of the formula fed infants was higher than that of the brest-fed infants. This data suggests the calcium and phosphorus intakes form human milk sufficiently support the growth of infants. Therefore, the level of calcium and phosphorus recommended dietary allowances for infants should be reduced.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.561-566
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• 2010

The effects of calcium concentrations of coating bag treatment to reduce berry cracking were investigated through the changes of pericarp structure and berry cracking rate in 'Kyoho' grape. The soluble solids and anthocyanin contents in harvested grapes were highest at $18.1^{\circ}Brix$ and $2.56{\mu}g{\cdot}cm^{-2}$ in non bagging group compared with those of calcium coating bag treatments. The firmness of pericarp was lowest in non bagging group ($1.18kg{\cdot}5mm^{-1}{\O}$) compared with bagging treatments (1.23, 1.24, 1.27, $1.35kg{\cdot}5mm^{-1}{\O}$) which increased effectively in proportion to calcium concentration. As a result of histological observation of the fruit skin, the bagging with higher calcium concentration developed thicker epidermal and sub-epidermal layer of cell wall than that of non bagging. Moreover, the strengthened berry skin of calcium treatments effectively decreased berry cracking rate under critical turgor pressure. However, the 9% calcium coating bag treatment which was the most effective for cracking reduction seriously decreased marketability of harvested grape with white color staining on berry skin caused by eluted calcium from the coated paper bag. Based on our results, we recommend that 6% calcium coating bag be available for berry cracking reduction and higher quality production.

• The Korean Journal of Pain
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• v.27 no.3
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• pp.229-238
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• 2014

Background: A toxic dose of bupivacaine produces vasodilation in isolated aortas. The goal of this in vitro study was to investigate the cellular mechanism associated with bupivacaine-induced vasodilation in isolated endothelium-denuded rat aortas precontracted with phenylephrine. Methods: Isolated endothelium-denuded rat aortas were suspended for isometric tension recordings. The effects of nifedipine, verapamil, iberiotoxin, 4-aminopyridine, barium chloride, and glibenclamide on bupivacaine concentration-response curves were assessed in endothelium-denuded aortas precontracted with phenylephrine. The effect of phenylephrine and KCl used for precontraction on bupivacaine-induced concentration-response curves was assessed. The effects of verapamil on phenylephrine concentration-response curves were assessed. The effects of bupivacaine on the intracellular calcium concentration ($[Ca^{2+}]_i$) and tension in aortas precontracted with phenylephrine were measured simultaneously with the acetoxymethyl ester of a fura-2-loaded aortic strip. Results: Pretreatment with potassium channel inhibitors had no effect on bupivacaine-induced relaxation in the endothelium-denuded aortas precontracted with phenylephrine, whereas verapamil or nifedipine attenuated bupivacaine-induced relaxation. The magnitude of the bupivacaine-induced relaxation was enhanced in the 100mM KCl-induced precontracted aortas compared with the phenylephrine-induced precontracted aortas. Verapamil attenuated the phenylephrine-induced contraction. The magnitude of the bupivacaine-induced relaxation was higher than that of the bupivacaine-induced $[Ca^{2+}]_i$ decrease in the aortas precontracted with phenylephrine. Conclusions: Taken together, these results suggest that toxic-dose bupivacaine-induced vasodilation appears to be mediated by decreased calcium sensitization in endothelium-denuded aortas precontracted with phenylephrine. In addition, potassium channel inhibitors had no effect on bupivacaine-induced relaxation. Toxic-dose bupivacaine-induced vasodilation may be partially associated with the inhibitory effect of voltage-operated calcium channels.

• The Journal of the Korea Contents Association
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• v.22 no.9
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• pp.583-591
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• 2022

The purpose of this study was to determine the incidence of dental erosion according to the type of lactic acid bacteria fermented oil and to identify a method for preventing dental erosion. For the lactic acid bacteria fermented milk, liquid fermented milk, condense-stirred type fermented milk, and condense-drink type fermented milk were used, and bovine tooth specimens used in the experiment were used. As a method to prevent dental erosion, the method of adding calcium to the lactic acid bacteria fermented milk, the method of applying high and low concentrations of fluoride to the teeth before exposure to the lactic acid bacteria fermented milk, and the method of applying these two methods together were measured to measure the preventive effect of dental erosion. As a result of immersing the specimen in the experimental beverage, the surface hardness of liquid fermented milk decreased the most. When comparing the difference in surface hardness before and after prophylaxis care, the Ca 2% group and the NaF 0.05%+Ca 0.5% group showed no significant difference from the negative control group, confirming that it is an effective method for preventing dental erosion. However, considering the change in taste and the stability of ingredients, a method of adding calcium at a low concentration rather than adding a high concentration of calcium is proposed. Therefore, it is recommended to use low-concentration calcium and low-concentration fluoride together to recognize the possibility of dental erosion when ingesting lactic acid bacteria and to prevent dental erosion caused by it.