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

• Journal of Nutrition and Health
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• v.33 no.2
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• pp.147-157
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• 2000

This study examined the effects of excess intake of calcium (Ca) and iron (Fe) supplement on bone loss, nephrocalcinosis and renal function in osteoporotic model rats. Seven-week-old female rats were first fed a Ca-deficient diet for four weeks after ovariectomy operation, and then one of nine experimental diets for additional eight weeks, containing three levels of Ca, normal (0.5%) or high (1.5%) or excess (2.5%) and three levels of Fe, normal (35ppm) or high (210ppm) or excess (350ppm). The osteoporotic model rats showed a remarkable increase in body weight, serum alkaline phosphatase (ALP) and decrease in breaking force, Ca, P, Mg contents of femur. Serum Ca concentration was not significantly affected by dietary Ca and Fe levles. Liver Ca content increased in rats fed a high-and excess-Ca diet. Kidney Ca content and microscopic Ca deposition remarkably increased in osteoporotic model rats compared to control group, and showed a tendency to decrease in rats fed a excess-Ca diet. Breaking force of femur increased with increasing dietary Ca levels, but Ca, P contents of femur and serum ALP were not significantly affected by dietary Ca and Fe levels. Serum total protein decreased in rats fed a excess-Ca diet, BUN increased in rats fed a excess-Ca diet, while serum uric acid and creatinine were not significantly affected by dietary Ca levels. Urinary creatinine, GFR increased in rats fed a high-and excess-Ca, diet, and GFR was highest in rats fed a excess-Ca/excess-Fe diet. These results suggest that excess intake of Ca may increase breaking force of femur, but not increase mineral contents of femur, and decrease kidney function. Furthermore, excess intake of Fe and Ca concurrently may aggravate kidney function leading to potential health problems in ovariectomized osteoporotic model rats.

• Journal of Nutrition and Health
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• v.28 no.5
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• pp.434-441
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• 1995

The model rats with postmenopausal osteoporosis were comparatively observed with regard to the effects of bovine ash and calcium phosphate on calcium metabolism. The modelling design involved the five week-old week-old female SD-strain rats ovariectomized and fed a low-Ca diet(20% casein, 0.06% Ca and 0.38% P) for three weeks. The rats were divided into five groups, one of which was fed the low-Ca diet(basal), and the rest of which were divided into five groups, one of which was fed the low-Ca diet(basal), and the rest of which were fed four kinds of Ca-supplemental diets(20% protein, 1.06% Ca and 0.8% P) for three weeks. The Ca-suplements diets contained two kinds of Ca sources, bovine bone ash(BBA) or calcium phosphate, tribasic [Ca3(PO4)2] and two kinds of protein sources, casein or isolated soy protein(ISP). The model rats of postmenopausal osteoporosis fed basal diet showed a significant decrease in Ca utilization in reference to serum Ca concentration, breaking force of bone, Ca and P contents of bone, and Ca absorption and retention. However, the supply of Ca for three weeks demonstrated the improved utilization of Ca. One step further, BBA was more effective than calcium phosphate in improving Ca utilization in ISP-fed groups. On the other hand, no significant difference was seen in casein-fed groups. It is to conclude that BBA could be more effective in accelerating Ca utilization under vulnerable dietary or physiological conditions such as vegetable protein intake and osteoprosis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3D
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• pp.329-334
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• 2009

The various behaviors of vehicular traffic flow are generated through both car-following and lane-changing behaviors of vehicles. Especially lane-usage varies by lane-changing behaviors. In the area of microscopic vehicle simulation, a lane-changing model connected to a car-following model parallel is essential to generate both various traffic flows relationships and laneusages. In Korea, some studies on car-following models have been reported, but few studies for lane-changing models stay in the beginning stage. In this paper, a two-lane changing model for the simulation modeling of large freeway network is introduced. The lane-changing model is developed based on CA (Cellular Automata) model. The developed model is parallel combined with an existing CA car-following model and tested on a closed link system. The results of simulation show that the developed model generates the various behaviors of lane usage, which existing CA lane-changing models could not generate. The presented model is expected to be used for the simulation of more various freeway traffic flows.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.78-88
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• 2015

Purpose: The objective of this study is to review researches regarding factors that potentially affect adolescent calcium (Ca) metabolism, and to suggest a potential modeling approach for optimizing gastrointestinal Ca absorption and peak bone mass. Background: Optimal gastrointestinal Ca absorption is a key to maximizing peak bone mass in adolescents. Urine Ca excretion in adolescents rises only after bone accretion is saturated, indicating that higher intestinal Ca absorption and bone retention is necessary to ensure maximum bone accretion. Hence, maximizing peak bone mass is possible by controlling the factors influencing gastrointestinal Ca absorption and bone accretion. However, a mechanism that explains the unique adolescent Ca metabolism has not yet been elucidated. Review: Dietary factors that enhance gastrointestinal Ca absorption may increase the available Ca pool usable for bone accretion, and a specific hormone may direct optimal Ca utilization to maximize peak bone mass. IGF-1 is an endocrine hormone whose levels peak during adolescence and increase fractional Ca absorption and bone Ca accretion. Prebiotics, generally obtained from dietary sources, have been reported to exert a beneficial effect on Ca absorption via microbiota activity. We selected and reviewed three candidates that could be used to propose a comprehensive Ca metabolic model for optimal Ca absorption and peak bone mass in adolescents. Modeling: Modeling has been used to investigate Ca metabolism and its regulators. Herein, we reviewed previous Ca modeling studies. Based on this review, we proposed a method for developing a comprehensive model that includes regulatory effectors of IGF-1 and prebiotics.

• Journal of Nutrition and Health
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• v.30 no.6
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• pp.605-613
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• 1997

This study was to investigate interaction between dietary protein and Ca levels in Ca metabolism and renal function in osteporosis rats. Five week-old female rats were fed a low Ca diet for 4 weeks after ovariectomy operation to establish rat models of osteoporosis. The ovariectomized osteoporosis rats were divided into six groups and were fed experimental diets which contained two levels of protein, normal (20%) and high(40%) , and three levels of Ca, low (0.06%), normal (0.47%) and high(0.94%) for 4 weeks , respectively. The ovaricetmized rat model of osteoporosis showed a remarkable decrease in serum Ca concentration, fresh weight and breaking force of femur, Ca and P contents of femur, and apparent absorption and retention of Ca. The supplementations of Ca and P contents of femur, and apparent absorption and retention of Ca. The supplementations of Ca at the dietary levels of normal and high levels significantly enhanced Ca bioavailability shown in the above experimental rat models of osteoporosis, regardless of dietary protein levels ; whereas the rats which were fed the low Ca diet demonstrated rather a decrease in its bioavailability. Irrespectively of the dietary Ca levels, the rats which were fed high protein diet exhibited an increase in kidney weight, urinary Ca, volume and hydroxyproline, and glomerular filtration ratio(GFR). The results show that dietary protein and calcium levels affect the renal function and Ca metabolism independently, while the interaction between protein and calcium have not been shown.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.209-217
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• 2010

Recently, some mathematical models for the prediction on progress of carbonation of concrete were reported. These models take account for $CO_2$ diffusion and chemical reaction between $Ca(OH)_2$ and $CO_2$. Based on the assumption that $CO_2$ diffuses in the carbonation zone and reacts with $Ca(OH)_2$ at the outer face of carbonation zone and non-carbonation zone. In this study, a mathematical model to predict the progress of carbonation of concrete has been established based on the reducing concentration of $Ca(OH)_2$ in the carbonation progress zone, where $Ca(OH)_2$ reacts with $CO_2$ and $Ca(OH)_2$ and $CaCO_3$ coexist. Also, the prediction model of carbonation progress rate of concrete using the air permeability coefficient regarding to $CO_2$ diffusion is developed. As a result of this study, an expression, the model equation is obtained for the prediction of carbonation based on the time and interaction velocity between $CO_2$ and Ca(OH)$_2$ dependent air permeability coefficient. The prediction by the model satisfied the experimental data of the accelerated carbonation for painted concrete. Consequently, the model can predict the rate of carbonation and the potential service life of concrete structure exposed to atmosphere.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.4
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• pp.217-239
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• 2011

We carried out a series of experiment demonstrating the role of mitochondria in the cytosolic and mitochondrial $Ca^{2+}$ transients and compared the results with those from computer simulation. In rat ventricular myocytes, increasing the rate of stimulation (1~3 Hz) made both the diastolic and systolic [$Ca^{2+}]$ bigger in mitochondria as well as in cytosol. As L-type $Ca^{2+}$ channel has key influence on the amplitude of $Ca^{2+}$ -induced $Ca^{2+}$ release, the relation between stimulus frequency and the amplitude of $Ca^{2+}$ transients was examined under the low density (1/10 of control) of L-type $Ca^{2+}$ channel in model simulation, where the relation was reversed. In experiment, block of $Ca^{2+}$ uniporter on mitochondrial inner membrane significantly reduced the amplitude of mitochondrial $Ca^{2+}$ transients, while it failed to affect the cytosolic $Ca^{2+}$ transients. In computer simulation, the amplitude of cytosolic $Ca^{2+}$ transients was not affected by removal of $Ca^{2+}$ uniporter. The application of carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP) known as a protonophore on mitochondrial membrane to rat ventricular myocytes gradually increased the diastolic [$Ca^{2+}$] in cytosol and eventually abolished the $Ca^{2+}$ transients, which was similarly reproduced in computer simulation. The model study suggests that the relative contribution of L-type $Ca^{2+}$ channel to total transsarcolemmal $Ca^{2+}$ flux could determine whether the cytosolic $Ca^{2+}$ transients become bigger or smaller with higher stimulus frequency. The present study also suggests that cytosolic $Ca^{2+}$ affects mitochondrial $Ca^{2+}$ in a beat-to-beat manner, however, removal of $Ca^{2+}$ influx mechanism into mitochondria does not affect the amplitude of cytosolic $Ca^{2+}$ transients.

• Korean Journal of Community Nutrition
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• v.5 no.2
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• pp.243-252
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• 2000

This study examined the effects of excess intake of calcium(Ca) and iron(Fe) supplements on iron bioavailability, liver and kidney functions in anemic model rats. Seven-week-old female rats were first fed and Fe-deficient diet for ten weeks, and then fed one of nine experimental diets for an additional eight weeks, containing three levels of Ca, normal (0.5%) or high(1.5%) or excess (2.5%) and three levels of Fe, normal(35ppm) or high(210 ppm) or excess(350ppm). In anemic model rats, serum Fe, total iron binding capacity(TIBC), hemogolin(Hb), hematocrit(Hct) and liver Fe contents were significantly decreased. Apparent Fe absorption significantly increased with increasing dietary Fe levels, and decreased with increasing dietary Ca levels. serum Fe concentration significantly increased in rats fed a high- and excess-Fe diet, and decreased in rats fed a excess-Ca diet. TIBC was decreawed in rats fed a excess-Ca diet, and transferrin saturation(%) increased in rats fed ahigh- and excess-Fe diet. Hb and Hct were decreased in rats fed an excess-Ca diet regardless of dietary Fe levels. Fe and thiobarbituric acid reactin gsubstance(TBARS) Contents of liver significantly increased in rats fed a high- and excess0-Fe diet, and decreased in rats fed a high- and excess-Ca diet. Fe content of the spleen showed similar results. Urinary creatinine and GFR increased in rats fed an excess-Ca diet regardless of dietary Fe levels. GOT, GPT and LDH were not significantly affected by dietary Ca and Fe levels. These results suggest that excess intake of Fe may increase liver Fe deposits and TBARS, and excess intake of Ca may decrease Fe bioavailability and kidney function leading to potential health problems in anemic model rats.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.11-16
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• 2010

Various researches have been performed on the topic of pedestrian traffic flow. At the beginning, the modeling and simulation method for the vehicular traffic flow was simply applied to pedestrian traffic flow. Recently, CA based simulation models are frequently applied to pedestrian flow analysis. Initially, the square Lattice Model is a base model for applying to pedestrians of counterflow and then Hexagonal Lattice Model improves its network as a hexagonal cell for more realistic movement of the avoidance of pedestrian conflicts. However these lattice models express only one directional movement because they express only one directional movement. In this paper, MLPM (the Multi-Layer Pedestrian Model) is suggested to give various origins and destinations for more realistic pedestrian motion in some place.