• Resources Recycling
• /
• v.23 no.2
• /
• pp.17-25
• /
• 2014

The thermal effect on the compositional change of the $SO_2$ absorption process product was investigated compared with the composition of raw material when dolomite is employed in place of lime in the scrubbing process based on thermodynamic estimation. It was considered that the equilibrium reactions which directly related with the formation of $CaSO_4$ and $MgSO_4$, the absorption process products, are those between $Ca^{2+}$ and $Ca(OH)_2$, $Mg^{2+}$ and $Mg(OH)_2$, and the secondary dissociation reaction of $H_2SO_4$. It was thought to be necessary to examine the enthalpy change for the formation reactions of $CaSO_4$ and $MgSO_4$ along with the thermal feature of the relative reactions to figure out the influence of temperature on the compositional change of absorption process products. The stable regions for $Ca(OH)_2$ and $Mg(OH)_2$ in Pourbaix diagram were found to be increased as temperature rises and the equilibrium reaction between $Ca^{2+}$ and $Ca(OH)_2$ was investigated to be more strongly influence by temperature change compared with the equilibrium reaction between $Mg^{2+}$ and $Mg(OH)_2$. The amounts of $CaSO_4$ and $MgSO_4$ were anticipated to be decreased with temperature considering the thermal characteristics for the equilibrium reactions regarding calcium, magnesium, and $H_2SO_4$. It was understood that the formation ratio between $CaSO_4$ and $MgSO_4$ is greater than the composition ratio between calcium and magnesium contained in dolomite at specific temperature and the decrease of the formation ratio of $CaSO_4$ and $MgSO_4$ with temperature was estimated to be diminished as the content of calcium in dolomite is increased. In addition, the extent of the change in the compositional ratio between absorption process products was examined to be reduced compared with the composition of raw material as the calcium content in dolomite is raised.

• Korean Journal of Food Science and Technology
• /
• v.30 no.5
• /
• pp.1197-1202
• /
• 1998

Organic acids-eggshell calcium salts were prepared to recycle calcium component from discarded egg shells, and the effects of addition of the salts on dough characteristics of raw noodle and physical properties of cooked noodle were also investigated. Based on Farinograms, calcium malate (CM) affected absorption, stability time, and development time more considerably than calcium citrate (CC). Maximum concentrations of both CM and CC with little influence on dough characteristics were found to be 0.1% and 0.4%, respectively. Addition of calcium salts led to reduce the volume expansion rate of cooked noodle and this was more clearly shown in a sample fortified with CM than CC. As for CC, addition of more than 0.6% resulted in rapid increase in springiness which was in a good agreement with sensory evaluation results. Calcium ion concentration of cooked noodle fortified with 0.4% CC was 48 ppm, equivalent to 86 mg of calcium obtained from 200 g of cooked noodle.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.1
• /
• pp.48-54
• /
• 2006

This study was conducted to investigate the effect of calcium and boron intakes on calcium utilization in ovariectomized (OVX) rats. Rats were divided into 9 groups and fed diets containing various levels of calcium $(0.1\%,\;0.5\%,\;1.5\%)$ and boron (0.5 ppm, 50 ppm, 100 ppm) for 4 weeks. The half of rats in each group were ovariectomized and the others were sham-operated. Rats were fed same diets for 8 weeks after operation. Feed intake and weight gain were significantly increased as the dietary calcium was increased and those of OVX group were higher than in sham-operated group. Feed efficiency ratio was significantly higher in OVX group than that in sham-operated one. With boron supplementation, serum calcium level was significantly increased in low-calcium group, but decreased in adequate/high-calcium group. In calcium balance, calcium intake was significantly increased with increasing levels of calcium and boron and higher in OVX group than that in sham-operated one. With increasing calcium intake, fecal and urinary calcium excretions were significantly increased. Urinary calcium excretion was significantly decreased with increment of boron intake. Apparent calcium absorption of adequate-calcium OVX group was the highest among the groups. Daily calcium retention was significantly increased as the dietary calcium was increased and that of high-calcium OVX group was higher than high-calcium sham-operated group. According to these results, the boron supplementation increased the calcium intake and decreased the urinary calcium excretion. Therefore, it could be suggested that the boron supplementation may be complementary to calcium nutrition and useful for bone health.

• Journal of Photoscience
• /
• v.3 no.3
• /
• pp.133-136
• /
• 1996

Calcium modulates the activity of guanylate cyclase and plays a key role in dark and light adaptation in the visual system. We have measured the Ca$^{2+}$, K$^+$ and Na$^+$ concentration in dark and light adapted bullfrog's (Rana catesbeiana) vitreous humor by using the atomic absorption spectrophotometer. The calcium concentration of the light adapted bullfrog's vitreous humor was higher than that of the dark adapted bullfrog's vitreous humor. This means that ion activity between the photoreceptor and vitreous humor side is light dependent and we have found that a Ca$^{2+}$ channel and Na$^+$ - Ca$^{2+}$ exchanger exist in the vitreous humor.

• Food Science and Biotechnology
• /
• v.15 no.2
• /
• pp.308-311
• /
• 2006

Saesongi (Pleurotus eryngii) was cultivated in both potato dextrose agar (PDA) and sawdust media supplemented with Ca salts. The addition of Ca phosphate and Ca carbonate to sawdust media did not affect the growth, whereas Ca sulfate addition suppressed the mycelial growth appreciably. The efficiencies of Ca accumulation in the fruiting were studied based on mycelial growth experiments on Ca-supplemented sawdust media. Supplementation with 0.1 to 5% Ca phosphate increased the Ca content in the fruiting body by 4.5-6.5 fold, to a level of $314.6{\pm}22.7$ to $449.7{\pm}29.3$.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.11a
• /
• pp.67-70
• /
• 2000

This study was performed to investigate the material behavior of hybrid thermoplastic composites contained glass fiber and calcium carbonate. The composite was prepared with each combination ratio of calcium carbonate, and the content of glass fiber was fixed with 10% by weight. In order to investigate the material behavior for various combination ratio, tension test, flexural test, and impact test were performed. Microscopic observation were conducted to examine the fractured surface of specimen for tension test. And the material behavior of the hybrid thermoplastic composite immersed in salt water with definite time was investigated.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.213-214
• /
• 2021

External insulation method is used to conserve energy of buildings. However, the current external insulation method uses organic insulating materials to become a diffusion path in case of fire. In this study, the purpose of this study is to provide basic data on the required performance of the plastering material according to the CaCO₃ powder addition of the finishing material of the external insulation method. In Figure 1, when powder was added, the adhesion strength decreased by 30% to 35% at 10% and 0% to 50% at 20% compared to Plain. In Figure 2, the moisture permeability increases approximately twice when powder is added. The results for the water absorption coefficient are shown in Figure 3.

• Journal of Nutrition and Health
• /
• v.26 no.3
• /
• pp.277-285
• /
• 1993

To investigate the effects of dietary calcium levels on the Ca metabolism in a rat model of ovariectomized osteoporosis, two studies were conducted. In Expt. I, five week-old femalc rats ovariectomized and fed a low Ca diet(0.06% Ca) for four weeks were compared with rats fed a normal (0.53% Ca) or low Ca diet under the sham-operated condition. Ovariectomized rats showed a significant increase in body weight and food intake. In rats fed the low Ca diet, a remarkable decrease was shown regardless of ovariectomy in serum Ca concentration, breaking force of bones, Ca and phopsphrus contents of bones, and apparent absorption and retention of Ca. Furthermore hte decrease of Ca contents of serum and bones in rats ovariectomized and fed the low Ca diet was similar to that in rats model of postmenopausal osteoporosis. In Expt. II, rats ovariectomized and fed on the low Ca diet for four weeks were divided into three groups, those given low Ca diet, normal Ca diet and high Ca diet(1.06%) respectively. The results indicated that supplementations of Ca at the intake level of 0.53% and 1.06% for 4 weeks tend to improve the relative Ca deficiency shown in experimental rat model of ovariectomized osteoporosis.

• International Journal of Concrete Structures and Materials
• /
• v.9 no.3
• /
• pp.295-306
• /
• 2015

Simulating natural leaching process for cementitious materials is essential to perform long-term safety assessments of repositories for nuclear waste. However, the current test methods in literature are time consuming, limited to crushed material and often produce small size samples which are not suitable for further testing. This paper presents the results from the study of the physical (gas permeability as well as chloride diffusion coefficient) and mechanical properties (tensile and compressive strength and elastic modulus) of solid cementitious specimens which have been depleted in calcium by the use of a newly developed method for accelerated calcium leaching of solid specimens of flexible size. The results show that up to 4 times increase in capillary water absorption, 10 times higher gas permeability and at least 3 times higher chloride diffusion rate, is expected due to complete leaching of the Portlandite. This coincides with a 70 % decrease in mechanical strength and more than 40 % decrease in elastic modulus.

• Geomechanics and Engineering
• /
• v.22 no.4
• /
• pp.329-337
• /
• 2020

Polyacrylamide (PAM) possesses high water absorption capacity and a unique pH-dependent behavior that confer large potential to enhance the engineering performance of clays. In this study, calcium bentonite was treated with a nonionic PAM. Flexible-wall permeability test and the consolidation test were performed at different pH values to evaluate the effects of PAM treatment on the hydraulic and consolidation properties. Test results demonstrate that index properties are affected by the adsorbed PAM on clay surface: a decrease in specific gravity, a decrease in net zeta potential, and an increase in liquid limit are observed due to the PAM treatment. At a given pH, the compressibility of the treated clay is greater than that of the untreated clay. However, the compression indices of untreated and treated clays can be expressed as a single function of the initial void ratio, regardless of pH. Hydraulic conductivity is reduced by PAM treatment about 5 times at both neutral and alkaline pH conditions under similar void ratios, because of the reduction in size of the water flow channel by PAM expansion. However, at acidic pH, the hydraulic conductivity of the treated clay is slightly higher than the untreated clay. This reflects that the treated bentonite with PAM can be beneficially used in barrier system for highly alkaline residues.