• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.12
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• pp.3899-3908
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• 1996

In order to clarify the effects of nonmetallic inclusion contents insteels (SM45C & SCM440) on the tool life, cutting experiment was performed under various cutting conditions. Tool life, cutting force, roughness of machined surface and cutting mechanism are examined on these two kinds of steel. The following conclusions were obtained from the analysis (1) Cutting force of the steels was not affected by chemical component and nonmetallic inclusion. (2) If the rate of amount, Ca/S has a value grater than about 0.2 and addition of less amount of Al, Mn, tool wear of tips decreasesinturning. (3) It is also proved that higher contents of nonmetallic inclusion improve roughness of the surface. (4) Less amount of Ca, higher amount of S, Mn and Al improve the chip breakability.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.1-5
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• 2013

Printing papers published in between 1950's and 1990's were treated with three methods such as distilled water washing, $CaCO_3$ solution washing and methyl cellulose solution coating for improving their conservational properties. Accelerated aging with $80^{\circ}C$ and 80% RH for 14 days was applied to the testing papers. Results showed that distilled water and $CaCO_3$ washing kept increased pH even after accelerated aging, but did not improve folding endurances for 1950's-60's papers. Methyl cellulose treatment did not increased pH of the old papers, but increased folding endurances remarkably for 1950's-60's papers even after accelerated aging. It suggests that methyl cellulose treatment after $CaCO_3$ washing should give improvements both in pH and folding endurance.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.41-47
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• 2002

La/sub 1-x/Ca/sub x/MnO₃ manganese oxide were grown using the floating zone image furnace with halogen lamps as heat source. The growth condition was 4∼6 mm/hr growth rate in air atmosphere, 45∼50 rpm and 20∼25 rpm of rotation rate of feedrod and growing crystal, respectively. Characterization analyses of the crystal were carried out using XRD, SEM, and EPMA. Orientation of crystal was determined using EBSD. The electromagnetic properties were measured with Quantum Design PPMS by 4 point probe method and resulted MR value of 462% at 215 K.

• Journal of Life Science
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• v.24 no.2
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• pp.112-117
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• 2014

We investigated the effects of extracts from Rubus coreanus (RC) and Artemisia princeps var. orientalis (AP) on DNA damage response in ultraviolet B (UVB)-exposed HaCaT cells. Cell activity upon treatment for 24 h with RC or AP alone was similar to or greater than that of the nontreated control. When UVB-exposed cells were postincubated for 24 h in medium containing RC or AP, cell activity increased in a concentration-dependent manner. Nuclear fragmentation analysis showed that postincubation with RC or AP decreased UVB-induced apoptosis by about 20% and 15%, respectively, of that in cells postincubated with growth medium. When UVB-exposed cells were postincubated for 24 h in medium containing RC or AP, the level of cyclobutane pyrimidine dimer decreased in a concentration- dependent manner. Western blot analysis showed that treatment of cells not exposed to UVB with RC or AP alone did not significantly change the levels of phospho-p53 and GADD45 protein. Interestingly, when UVB-exposed cells were postincubated for 24 h in medium containing RC or AP, phospho-p53 and GADD45 levels decreased in a concentration dependent manner. Our results suggest that RC and AP extract assist the survival of UVB-exposed cells in parallel with a decrease in levels of UVB-induced DNA damage and damage-response proteins, such as p53 and GADD45.

• Korean journal of applied entomology
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• v.17 no.3 s.36
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• pp.155-160
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• 1978

This experiment was carried out to develope a technique for labelling pine gall midge with ·radioactive phosphorus and calcium. This technique evolved would help to obtain basic information on the appropriate concentration of $^{32}P\; and\; ^{45}Ca$ in tagging and determination of adult flight ranges which considered as one of the factors in dissemination. 1. Labelling at the larval stage of pine gall midge by injection of $^{45}Ca$ into pine tree trunk appeared not to be effective for tagging the adults because radioactivity was gradually decreased to background by emergence. 2. The radioactivities of larvae in the galls gradually increased in September but from October 1 the activity was gradually decreased for 10 days then equilibrium was maintained thereafter. The results seem to indicate that larval diet termination occured early October. 3. A maximum level of radiation was detected at 3 weeks after $^{32}P$ injection and thereafter it was gradually reduced. This result implies that $^{32}P$ is not appropriate radioisotope in labelling pine gall midge through trunk injection method. 4. After washing in running water for 10 minutes, the optimum$^{32}P$ concentration for treated overwintered larvae and pupae was found to be 0.5 micro curie per ml. for 30 minutes dipping.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.5
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• pp.529-535
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• 1997

The present study was aimed at investigating whether the vascular calcium regulation is altered in hypertension. Two-kidney, one clip (2K1C) and deoxycorticosterone acetate (DOCA)-salt hypertension were made in rats, and their thoracic aortae were taken 4 weeks later. The isometric contractile response and calcium uptake of the endothelium-denuded aortic preparations were determined. Caffeine ($0.1{\sim}35\;mmol/L$) induced a greater contraction in 2K1C and DOCA-salt hypertension than in normotensive control. When the vascular calcium store was functionally-depleted by a repeated exposure to caffeine, it took longer to reload the store and to resume the initial contraction force in response to caffeine in both 2K1C and DOCA-salt hypertension. The vascular $^{45}Ca$ uptake following the functional depletion of the cellular store was also greater in both models of hypertension than in control. Ryanodine, calcium channel activator of the sarcoplasmic reticulum, attenuated the restoration of caffeine-induced vascular contraction, which was not affected by either 2K1C or DOCA-salt hypertension. Nifedipine, an L-type $Ca^{2+}$ channel blocker, attenuated the restoration of caffeine-induced contraction, which was not affected by DOCA-salt hypertension, but was more pronounced in 2K1C hypertension. Nifedipine also diminished the vascular $^{45}Ca$ uptake, which was not affected by DOCA-salt hypertension, but was more pronounced in 2K1C hypertension. Ouabain, a $Na^+,\;K^+-ATPase$ inhibitor, increased the caffeine-induced contraction by a similar magnitude in control and 2K1C hypertension, which was, however, markedly attenuated in DOCA-salt hypertension. Ouabain enhanced the vascular $^{45}Ca$ uptake, the degree of which was not affected by 2K1C hypertension, but was markedly attenuated in DOCA-salt hypertension compared with that in control. Cyclopiazonic acid, a selective inhibitor of $Ca^{2+}-ATPase$ of the sarcoplasmic reticulum, attenuated the restoration of caffeine-induced contraction, which was not affected by 2K1C hypertension, but was more marked in DOCA-salt hypertension. These results suggest that the increased vascular calcium storage may be attributed to an enhanced calcium influx in 2K1C hypertension, and to an impaired $Na^+-K^+$ pump activity of the cell membrane and subsequently increased calcium pump activity of the cellular store in DOCA-salt hypertension.

• Journal of Ginseng Research
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• v.45 no.6
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• pp.683-694
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• 2021

Background: Ginsenoside Rg1 (Rg1) has been well documented to be effective against various cardiovascular disease. The aim of this study is to evaluate the effect of Rg1 on mechanical stress-induced cardiac injury and its possible mechanism with a focus on the calcium sensing receptor (CaSR) signaling pathway. Methods: Mechanical stress was implemented on rats through abdominal aortic constriction (AAC) procedure and on cardiomyocytes and cardiac fibroblasts by mechanical stretching with Bioflex Collagen I plates. The effects of Rg1 on cell hypertrophy, fibrosis, cardiac function, [Ca²⁺]_i, and the expression of CaSR and calcineurin (CaN) were assayed both on rat and cellular level. Results: Rg1 alleviated cardiac hypertrophy and fibrosis, and improved cardiac decompensation induced by AAC in rat myocardial tissue and cultured cardiomyocytes and cardiac fibroblasts. Importantly, Rg1 treatment inhibited CaSR expression and increase of [Ca²⁺]_i, which similar to the CaSR inhibitor NPS2143. In addition, Rg1 treatment inhibited CaN and TGF-b1 pathways activation. Mechanistic analysis showed that the CaSR agonist GdCl₃ could not further increase the [Ca²⁺]_i and CaN pathway related protein expression induced by mechanical stretching in cultured cardiomyocytes. CsA, an inhibitor of CaN, inhibited cardiac hypertrophy, cardiac fibrosis, [Ca²⁺]_i and CaN signaling but had no effect on CaSR expression. Conclusion: The activation of CaN pathway and the increase of [Ca²⁺]_i mediated by CaSR are involved in cardiac hypertrophy and fibrosis, that may be the target of cardioprotection of Rg1 against myocardial injury.

• The Korean Journal of Physiology
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• v.10 no.1
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• pp.1-5
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• 1976

The trypanocidal drug suramin, an impermeant polyanion, has been shown to be a powerful inhibitor of the calcium uptake and calcium-stimulated ATPase activity of sarcoplasmic reticulum (Fortes et al., 1974). In view of this finding, an attempt was made to investigate the effect of suramin on $Ca^{++}$ transport in resealed red cells and on $Ca^{++}$-activated ATPase in red blood cell membrane fragments (RBCMF). The results obtained are summarized as follows. 1. $Ca^{++}$ outflux from the resealed RBC was inhibited by suramin and the inhibitory action of suramin is proportional to the concentration of drug added inside the RBC preparation. When suramin is added both inside and outside the RBC preparation simultaneously, the magnitude of the inhibitory effect was more pronounced, suggesting that suramin inhibits both active $Ca^{++}-^{45}Ca$ exchange diffusion across the RBC membrane. 2. Suramin inhibits the $Ca^{++}$-activated ATPase of the RBCMF and the effect of inhibition by the drug was also concentration dependent. From the above results, it may be concluded that suramin inhibits $Ca^{++}$ transport across RBC membrane by inhibiting $Ca^{++}$-activated ATPase activity which has been known to be linked with active $Ca^{++}$ transport.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.2
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• pp.115-121
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• 1987

A pot experiment was conducted to investigate the influence of Ca and Mg saturation ratios of soil on the uptake of Ca, Mg and K by rice plant. A silty loam soil was treated with $CaCl_2$ and $MgCl_2$ to obtain different degrees of Ca and Mg saturation. The studied ranges of Ca and Mg saturation ratios were 81:19, 70:30, 52:48, 55:45, and 31:69 in terms of the ratio of exchangeable Ca and Mg. Two levels of K application (90kg/ha, and 180kg/10a as $K_2O$) were also included in this study. The significant observation were summarized as follows. 1. When the Ca saturation of soil was dominant over Mg, the soil solution contained more Ca than Mg and vice versa. These led to the higher uptake of Ca by rice plant in Ca dominant soils and higher uptake of Mg in Mg dominant soils. 2. When the Ca and Mg saturation ratio was about equal, more Mg was released to soil solution leading to higher concentration of Mg in rice plant compare to that of Ca. 3. A trend was observed that the concentration of K in soil solution was lower in Mg dominant soils than in Ca dominant soils. This also resulted in the depressed uptake of K by rice plant under Mg dominant system when compare to Ca dominant system. 4. The increase application of K led to the increase in relative concentration of K to (Ca+Mg+K), and to the depression of divalent uptake by rice plant. However, it was observed that the degree of depression in uptake divalent by K application was more sensitive in case of Mg than that of Ca. 5. When viewed from grain yield of rice, it is pointed out that the optimum range of Ca to Mg ratio in soil may fall in the vicinity of 7:3. 6. Although K uptake by rice plant was influenced by the term of $AK^+/{\sqrt{A(Ca^{{+}{+}}+Mg^{{+}{+}})$ in soil solution, $AK^+$ itself was affected by the ratios of Ca:Mg in soil, as it were $AK^+$ value was decreased in Mg dominant soil than in Ca.

• The Korean Journal of Malacology
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• v.28 no.4
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• pp.343-347
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• 2012

The growth rates of offspring of selected abalone (SA), Haliotis discus hannai, population for rapid growth were compared to those of offsping of the control abalone (CA) at bred under the same condition. The growth traits (shell length, shell breadth and total weight) of SA were significantly faster than those of CA at this experiment. At the 45th day and 90th day, the growth rates in shell length of SA were estimated 31.7% and 17.8% faster than those of CA, total weight of SA were estimated 43.7% and 25.6%, respectively. Moreover, the relative growth rate between shell length and total weight of SA showed significant differences higher than one in CA at 90th day. The results suggest a possibility of improving the growth rate of cultured abalone using selection techniques.