• Journal of Korean Society on Water Environment
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• v.32 no.5
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• pp.458-464
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• 2016

This study evaluated the dewatering efficiency of inorganic dehydrating agents that contain oyster shells. A filter press dehydrator was used for this study. The experiments were performed by the single injection of calcium-based chemicals, the single injection of oyster shells, and the mixed injection of oyster shells and calcium-based chemicals. The moisture content of the dewatered cake generated after dehydration confirmed that the best dewatering efficiency was found at the mixing ratios of CaCO₃ to sludge, oyster shell to sludge, and inorganic dehydrating agent to sludge of 3:1, 10:1, and 1.5:2.5:1, respectively. The moisture contents exhibited less than 58% when the injection mixing ratio of inorganic dehydrating agent to sludge was 1.5:2.5:1. From EPS, SEM, and EDX analysis, it was found that the calcium adsorbed on the sludge surface could reduce extracellular polymeric substances (EPSs) and enhanced the dewaterbility. Based on the above results, it is considered possible to apply inorganic dehydrating agents containing recycled oyster shells in sludge dewatering in order to reduce sludge.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.483-487
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• 2001

As a part of basic investigation for utilizing of cuttle bone as a calcium source, we examined on the extraction methods (calcining at $800^{\circ}C$ for 2 hrs, autoclaving at $121^{\circ}C$ for 10 hrs and ultrasonic treatments at $60^{\circ}C$ for 10 hrs) as a pretreatment methods for preparation of calcium-based powder from cuttle bone, The color of calcined calcium-based powder from cuttle bone was white, while that treated by other methods was light yellow. The calcium content in calcined calcium-based powder was $70.5\%$, and revealed high about 2 times compared to those pretreated by other methods. And, calcium solubility in calcined calcium-based powder was improved 22 times compared to raw cuttle bone powder, Among calcining, autoclaving and ultrasonic treatments as a pretreaoent methods for preparation of calcium-based powder from cuttle bone, calcining treatment was superior to other methods on the aspect of color, calcium solubility and purity of calcium-based powder, Judging from X-ray diffraction pattern of calcined calcium-based powder, most of calcium was present as a form of calcium oxide, But, pH of calcined calcium-based powder revealed strong alkali of pH 12.9. This pH value might invoke health risk in using food resource. Therefore, for utilization effectively calcined calcium-based powder from cuttle bone, it requires a suitable treatment such as adjustment of pH to neutral condition.

• Korean Journal of Veterinary Research
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• v.36 no.3
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• pp.709-718
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• 1996

This experiment was carried out to clarify the effect of lead poisoning on the lead and essential trace elements homeostasis of tissues in rats. Fifty female Wistar rats, 7 weeks old, were divided into four experimental groups(B, C, D, and E) and a control(A). The four experimental groups received diets contaminated artificially with 10 (B group), 100 (C group), 1,000 (D group) and 5,000 (E group) ${\mu}g/g$ of lead as lead acetate, respectively. The control group received normal diet. Rats were necropsied on the 4th or 8th week of experimental periods and heart, liver, spleen, kidney, muscle, lung and hair were taken. The tissues were analysed for lead, copper, zinc, iron and calcium content by atomic absorption spectrophotometry. From these experiments following results ware obtained ; In C group, lead content of the heart, liver, kidney and hair were significantly increased both on the 4th and 8th week of experiment. In D and E group, lead content of all tissues including heart, liver, spleen, kidney, muscle, hair and lung were significantly increased in accordance with the lead contamination both on the 4th and 8th week of experiment. In C group, copper content of tissues were significantly increased in the heart, liver, kidney and lung on the 4th week and all tissues on the 8th week of experimental periods. In D and E group, copper content of the liver were significantly increased both on the 4th and 8th week of experiment. But the copper content of tissues were gradually decreased compared with C group in accordance with the lead contamination. Especially the content in spleen, heart or kidney were significantly decreased compared with the control group. The zinc content of kidney, heart, or spleen were decreased in D and E groups whereas the iron and calcium content showed no significant change.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.137-145
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• 1981

The mutual effects of calcium, potassium and boron on the growth of the leaf lettuce and its following crop of soybean in the granite soil were observed. The results obtained were as follows : 1. The yields of leaf lettuce and soybean were greatly increased by the application of calcium. It was observed that the calcium content in soybean leaf correlated positively with the yields, the number of pods and dry weight of soybean. 2. The application of calcium was effective by itself on the plant growth, the Ca+B application was better effective, and the best effective plot was $Ca+B_1+K_1$. 3. No significant tendency was observed between the Ca/B ratio in plant tissue and its growth. 4. The application of boron increased calcium absorption in plant tissue regardless of the application of calcium. 5. The number of pods and 100 grains weight of soybean were increased by the application of boron, And a positive correlation was observed between the boron content in soybean leaf and the number of pods of soybean. 6. One basal application of calcium, potassium and boron was effective both on leaf lettuce and on its following crop of soybean.

• Korean Journal of Agricultural Science
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• v.3 no.2
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• pp.139-144
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• 1976

To deter-mine the most reasonable method for improving of newly reclaimed soil, seven kinds of improving methods were tested and the soybean was cultivated as test crop. The results obtained are summarized as follow: The newly reclaimed soil where this experiment was carried out showed low acidity and was deficient in the humus, the phosphate, the calcium and the magnesium. Both the fused phosphate as well as the calcium was much effective to the correction of the soil acidity. The compost was the most effective source to increase the content of the humus in the soil, and also the calcium application showed a significant effect to increase the amount of humus. Not only compost but also fused phosphate were much effective to increase the content of calcium in the soil. Each factor as the calcium, the fused phosphate, the compost and the deep plowing has an effect to increase the amount of magnesium in soil significantly. The compost increased the potassium in soil. The amount of magnesium in soybean plant was significantly increased by the application of the calcium, the fused phosphate or the compost. And the calcium and the fused phosphate had an effect to increase the grain yield of soybean. The highest grain yield of soybean was taken at the treatment of N.P.K.+Compost+Calcium+Deep-plowing. The grain yield of soybean was significantly correlated with the soil acidity, the amount of the humus and the magnesium in soil and the amount of the magnesium in soybean plant.

• Journal of Nutrition and Health
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• v.38 no.7
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• pp.544-552
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• 2005

This study was conducted to examine the correlation among bone mineral density (BMD), hair and nail calcium and magnesium contents, and nutrient intakes in preschool children in Chungnam district. A total of 111 preschool children (61 boys, 50 girls) measured the anthropometric characteristics, the bone mineral density of carpus using DEXA and hair and nail calcium and magnesium contents were analyzed by ICP spectrometer. The average ages of the study subjects were 55.7 months in boys and 53.0 months in girls (3.8${\~}$7 years). The birth height and weight of subjects were 51.0 cm and 3.3 kg in boys and 50.3cm and 3.2kg in girls, respectively. The average height, weight, $\%$ body fat, and obesity index were 111.6 cm, 19.6 kg, $15.0\%,\;96.1\%$ in boys and 108.6 cm, 18.5 kg, $17.5\%,\;98.1\%$ in girls, respectively. The bone mineral density in carpus was $0.25 g/cm^2$ in boys and $0.24 g/cm^2$ in girls. The hair calcium and magnesium contents were 440.9 ppm, 16.4 ppm in boys and 373.2 ppm, 28.9 ppm in girls. The nail calcium and magnesium contents were 9.4 ppm, 2.1 ppm in boys and 10.4 ppm, 2.4 ppm in girls. The intakes of energy, calcium, iron, zinc, vitamin A. niacin, and vitamin C did not meet the Korean RDAs. The ultradis and average carpus BMD were positively correlated to the plant calcium intake (p < 0.05, p < 0.05). And the ultradis, distal, and average carpus BMD were positively correlated to the plant iron intake (p < 0.05, p < 0.05, p < 0.05). The average bone mineral density in the carpus was positively correlated to the nail magnesium content (p < 0.05). Therefore, more systematic studies to investigate the roles of iron and calcium intakes, nail magnesium content in bone development of preschool children were required.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.315-320
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• 1996

In this paper, we investigated the retention amounts(ash contents) according to the addition amounts of retention aid and calcium carbonate and compared the mechanical and optical properties of sheets under the same ash content. As the addition amounts of retention aid increase, the retention of calcium carbonate, that is, ash contents of sheets increase in all retention system. In this case, the sheets included ash content as already expected is produced by adjusting the addition amounts of retention aid and calcium carbonate. Tensile index, burst index, tear index, internal bonding strength of sheets straightly decrease as the ash content of sheets increases. Especially, in the same ash content, all sorts of strength are high in compozil system, low in dual polymer system. Opacity increases along with according to the increase of ash content, and is high in hydrocol system, the worst in dual polymer system. In equal opacity, the strength of paper decreases compozil, hydrocol, and dual polymer system in order. But to judge she superiority or inferiority of retention aids, it should consider the various factors such as the optimum production and process conditions besides the retention amounts of filler and the sheet strength.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1266-1271
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• 2007

This study examined effects of calcium supplemented milk on bone loss in ovariectomized rats. Twenty four Sprague-Dawley female rats, 7 weeks-old, were divided into 4 groups, ovariectomized and fed diets containing: 1) control, no Ca supplemented milk, 2) ovx 1, Ca carbonate supplemented milk, 3) ovx 2, ionized Ca supplemented milk, and 4) ovx 3, nano Ca supplemented milk. All rats were fed 1 ml of milk containing 20 mg supplemented Ca. After 18 wk feeding, body weight gain and food efficiency ratio were significantly different between ovx 1 and ovx 3. Serum concentration of calcium and phosphorus were not different among groups. However, there was a significant difference in calcium content of dry femoral weight in ovx 3 compared with the control and ovx 2. In addition, femoral bone mineral density ($g/cm^2$) was significantly greater in ovx 3 than in other groups (p<0.05). The ovx 3 group showed the highest stiffness (N/mm), maximum energy (N) in femur and trabecular bone area (%). The present study indicated that nano Ca supplementation in milk may be an effective way to enhance bone calcium metabolism for ovariectomized rats.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.10
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• pp.1477-1482
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• 2016

This study was conducted to investigate the effects of diets with varying levels of calcium on egg production, shell quality and overall calcium status in aged laying hens. A total of five hundred 70-wk-old Hy-Line Brown layers were divided five groups and fed one of the five experimental diets with 3.5%, 3.8%, 4.1%, 4.4%, or 4.7% Ca, for 10 weeks. There were no significant differences in feed intake, egg production and egg weight among groups. The cracked eggs were linearly reduced as dietary Ca levels increased to 4.7% (p<0.01). A significant linear improvement for eggshell strength and thickness were determined with increasing dietary Ca levels (p<0.01). The contents of serum Ca and phosphorus were not affected by dietary Ca levels. With increase in dietary Ca levels, the tibial breaking strength slightly increased. There were no significant differences in the tibial contents of ash, Ca and phosphorus among groups. In conclusion, eggshell quality, as measured by appearance, strength and thickness of eggshell, were influenced by dietary Ca content as expected (p<0.05). These results suggested that aged laying hens require relatively higher level of Ca than required levels from current Korean feeding standards for poultry.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.1
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• pp.13-22
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• 1994

This study was designed to investigate the effects of dietary protein and caffeine consumption levels on Ca, P, Na and K metabolism. One hundred twenty rats were divided into twelve groups according to age, protein level and caffeine consumption such as group(120-130g young rat, 250-300g adult rat) , dietary protein group (20% normal protein , 85 low protein) , caffeine consumption group(0, 3.5mg, 7.0mg). Low protein diet containing high caffeine levels caffeine levels increased calcium, phosphorus, sodium and potassium contents of urine and fecal in rats. Young rat has higher level of calcium, phosphorus , sodium and potassium than adult rat. In the serum, calcium contents were not affected by age, dietary protein levels and caffeine consumption . However, phosphorus, sodium and potassium contents of serum in adult rat were higher than young rat. In the liver, potassium decreased with decreasing dietary protein levels. In the kidney, calcium , phosphorus and potassium contents were not different by age group, dietary protein levels and caffeine consumption , but sodium content was significantly reduced in the adult rat.