• Nutrition Research and Practice
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• v.7 no.4
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• pp.309-314
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• 2013

This study was conducted to investigate the relationship among the current status of calcium intake from milk and milk products, physical growth and bone mineral density in 664 male and female middle school and high school students aged 15-17 years. In the study, the current status of calcium intake from milk and milk products was analyzed, and the height, body composition, and bone mineral density of the right heel bone (calcaneus) were measured. The daily calcium intake of milk and milk products was calculated as the 'dairy equivalent of calcium', which is the calcium content in 200 mL of white milk. The cutoffs of tertiles of the dairy equivalent of calcium were calculated and then the subjects were categorized into 3 groups according to the tertiles, Q1 group (lower intake group), Q2 group (middle intake group) and Q3 group (upper intake group). The daily calcium intake of milk and milk products in Q1, Q2 and Q3 groups was 16.2 mg, 99.7 mg, and 284.0 mg, respectively, and the ratio of milk and milk product consumption to the daily total calcium intake was 5.4%, 27.4%, and 49.7%, respectively. The ratio of total calcium intake to the daily recommended intake in study subjects was 30.5% in Q1, 42.3% in Q2, and 60.7% in Q3, with significant differences (P < 0.05). Height, body weight, BMI, and % of body fat in three tertile groups (Q1, Q2 and Q3) were not significantly different. However, the T scores for bone mineral density in female students in three tertile groups (Q1, Q2 and Q3) was significantly different (P < 0.05). The study showed that the intake of milk and milk products in adolescents, particularly in girls, can improve the bone mineral density without increasing body weight, and thus confirmed that milk intake is important in adolescence.

• Journal of the Korean Geosynthetics Society
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• v.18 no.2
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• pp.1-10
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• 2019

This study was intended to evaluate the water permeability and structure for calcium bentonite-sand mixtures to utilize calcium bentonite as a liner. This study conducted physico-chemical properties tests, compaction tests, permeability test and Scanning Electron Microscopy analysis (SEM) analysis. It was found the higher the ratio of calcium bentonite, the lower the dry density with coefficient of permeability, and the higher the optimum moisture content. In particular, SEM analysis was found the higher the ratio of calcium bentonite, the higher the area of the montmorillonite particles. In conclusion, the optimum coefficient of permeability that finds the landfill liner condition (must be less than $1{\times}10^{-7}cm/sec$) was obtained when the ratio of calcium bentonite was 40% or higher. These findings may improve the understanding of the calcium bentonite as a liner. Calcium bentonite shows a similar permeability to sodium bentonite 7% when mixed at 40% or more. Therefore, it is considered that calcium bentonite can be utilized as a liner.

• Korean Journal of Plant Resources
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• v.10 no.1
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• pp.11-16
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• 1997

Effects of calcium on the total tuber yield, dry matter content, internal brown spot and hollow heart of a processing potato cv. Atlantic were investigated to obtain some basic informations in summer cropping. The occurrence rate of the internal brown spots in cv. Atlantic tubers were highly decreased with the significant differences in the Ca-treated plots compared to the Ca-nontreated plots. However, no significant differences amongs Ca-treated plots were shown. Plant height and the number of main stems were not affected by the changes of the calcium levels, but top fresh weight was the highest in the plots of Ca(200kg/ha) level. In addition to its total yield, dry matter content, hollow heart was not affected by calcium fertilization. Therefore, the causal factor of the internal brown spot is attributed to the calcium deficiency in the tubers of cv. Atlantic.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.337-340
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• 1987

This experiment was conducted on relatively acid sandy loam soil at Choong-ju campus, Kon-kuk University aimed at clarifying the influence of urea and ammonium nitrate on the effect of potassium to Chinese cabbage in soils either limed or unlimed with calcium silicate. The results are summarized as follows: a. Calcium silicate application enhanced cabbage growth and under this condition, the difference in effect of urea and ammonium nitrate can hardly be observed. b. Without calcium silicate application, the response of Chinese cabbage to ammonium nitrate was more distinctive than that to urea. This was partially attributable to the greater use of soil born potassium at ammonium nitrate treatment. c. Added potassium was not only affective in increasing cabbage yield but also contributed in improving quality of cabbage by producing greater edible portion of the cabbage. Such K effect was particularly pronounced on the acid soil where calcium silicate application was neglected. d. Potassium was easily translocated from outer leaves to inner leaves and thus, the concentration of K content in outer leaves played as a limiting factor of cabbage yield. Less than 20 me/100gr of K content in harvested dried outer leaves resulted in a linear reduction of cabbage yield.

• 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 $140{\sim}151\;mg\%,\;210{\sim}220\;mg\%$.

• Horticultural Science & Technology
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• v.18 no.5
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• pp.605-611
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• 2000

This experiment was conducted to examine the effects of foliar application of ethychlozate and ethyclozate mixed with different calcium formulae (clef-non, suical, cell-bine, and calcium acetate monohydrate) on the fruit quality and peel puffing of 'Miyagawa Wase' satsuma mandarin cultivated in a plastic film house. Foliar application of ethychlozate mixed with clef-non or suical showed a result that the 'a' value of peel chromaticity was increased, which are supposed to accelerate peel coloration without peel puffing. The reducing sugar levels of fruits in control, ethychlozate, ethychlozate+celef-non, ethychlozate+suical, ethychlozate+cell-bine, and ethychlozate+calcium acetate monohydrate treatment were 4.98, 5.30, 5.59, 5.00, 5.20, and 4.27%, respectively. Especially, in the case of ethychlozate mixed with clef-non, the reducing sugar level was 0.61% higher than that of control. Sucrose and total sugar content also had a similar trend as that in the reducing sugar contents. The sugar contents of fruits in various ethychlozate treatments mixed with different calcium formulae except those in ethychlozate treatment or ethychlozate treatment mixed with calcium acetate monohydrate were higher than $12^{\circ}Brix$. Especially, the treatment of ethychlozate treatment mixed with clef-non showed the highest sugar content with $12.7^{\circ}Brix$. The ratio of soluble solids to acidity also showed the similar tendency, but there was no significant difference in acidity among the treatments.

• Resources Recycling
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• v.11 no.4
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• pp.27-36
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• 2002

The clinker of which main component was calcium-chloroaluminate ($l1CaOㆍ7Al_2$$O_3$ㆍ$CaCl_2$), was synthesized with the bottom ash of municipal solid waste incinerator ash. The hydration mechanism and synthesis temperature of calcium-chloro-aluminate were investigated. The synthesized clinker was blended with a cement. It was substituted with 3～13 wt.% for clinker and $CaSO_4$ of ordinary portland cement. The compressive strength and the content of leached heavy metals of its mortar were measured. Calcium-chloroaluminate was synthesized above $800^{\circ}C$ and its main hydrate was ettringite ($3CaOㆍAl_2$$O_3$ㆍ$3CaSO_4$ㆍ$32H_2$O). The calcium-chloroaluminate was also synthesized above $800^{\circ}C$ with the bottom ash of which size fraction was below 30 mesh mainly. The compressive strength of the blended cement mortar was increased as the additive content of the clinker synthesized from the bottom ash was increased by 11 wt.%. The concentration of heavy metals leached from each mortar was satisfied with the value of the environmental standards and regulations.

• 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 Society of Food Science and Nutrition
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• v.37 no.4
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• pp.459-464
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• 2008

This study was performed to investigate the effect of calcium-rich large anchovy on calcium metabolism in rats for 5 weeks. Experimental animals were randomly assigned to 5 treatments with 14 heads of Spraque Dawley male rats in each group. The experimental diets were as follows; market milk group (M) as control, market milk+calcium-rich large anchovy group (MA), market milk＋calcium carbonate group (MC), market milk+calcium lactate group (ML), and enriched-calcium market milk group (M2), which were formulated with commercially semi-purified rat chow (AIN-diet) to maintain the same level of calcium (1%) in all groups. Femur lengths of M and M2 groups were significantly higher than other groups. Bone mineral density (BMD) and bone mineral content (BMC) and calcium content of femur were the highest in MA group than other groups. In vitro and in vivo calcium absorption rates were high in MA group (7.30% vs 27.50%) compared with those of the other groups. Serum total-cholesterol and HDL-cholesterol levels were significantly different between M group and MA group (p<0.05). Creatinine levels were significantly higher in M, MA and MC groups than in M2 group (p<0.05). Serum calcium, osteocalcin and ALPase activities were higher in calcium-rich large anchovy (MA) group among the treatments, but there was no significant difference. SGOT activity was significantly lower in M2 group than those of M, MA and MC groups (p<0.05). These results may indicate that the calcium-rich large anchovy has enforced the BMD, BMC and calcium absorption rates of in vitro and in vivo compared with the other groups and might be a calcium-enriched food with large anchovy.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.3
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• pp.175-184
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• 2002

Soil chemical parameters of peach orchards and the concentration of nutrients in peach leaves were investigated. Results of soil analysis showed that pH value and content of exchangeable calcium was quite low, required to adjust soil acidity in many investigated soils. Nitrogen and phosphorous contents in leaves were founded to be excessive comparing to RDA's optimal levels(N $29.3{\sim}35.9g\;kg^{-1}$, P $1.7{\sim}2.2g\;kg^{-1}$), while calcium contents were lower than optimal levels($11.2{\sim}21.0g\;kg^{-1}$) in many sites and Potassium content was higher in peach cultivars than nectarine cultivars. Correlation analysis revealed that organic matter contents in subsoils and exchangeable calcium content in soils(top and subsoil) were increased with cultivation year, but available phosphate contents in subsoils were decreased. Organic matter and exchangeable magnesium contents in top soils were positively correlated with potassium and magnesium contents in leaves, whereas were negatively correlated with calcium contents in leaves, impling antagonistic absorption of calcium against potassium and magnesium. The findings indicated that most of soils ought to managed to adjust soil acidity and application amount of nitrogen, phosphorous fertilizer and compost should be controlled properly.