• Journal of Nutrition and Health
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• 제36권9호
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• pp.942-949
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• 2003

This study was longitudinally conducted to evaluate the intakes of protein, Ca, Mg and P of exclusively breast-fed infants compared with the Recommended Dietary Allowances (RDA) for Korean infants. Twenty Korean lactating women and their infants during the first 3 months of lactation in Incheon area were participated. Protein, Ca and Mg, and P contents in the milk were determined using semimicro Kjeldahl (N ${\times}$ 6.38) , atomic absorption spectrophotometer and colorimeter, respectively, and also the milk consumption of the infants was measured by the test-weighing method. Protein contents of the milk were 1.96, 1.63, 1.51, 1.25 and 1.16 g/100 ml, and protein intakes of the breast-fed infants were 9.00, 9.85, 9.17, 8.97 and 7.76 g/day at 7, 15, 30, 60 and 90 days postpartum. The average protein intake per body weight of the breast-fed infants was 1.84 g/kg/day. The average intakes of Ca, Mg, P were 172.1 mg/day, 15.2 mg/day and 91.4 mg/day, respectively, and the average Ca/P ratio was 1.91. There was positive correlation between protein and Ca, protein and p, and Ca and P contents while negative correlation between Mg and P, The body weight of breast-fed infants increased normally from 3.6 $\pm$ 0.41 g at birth to three month during lactation. It is suggested that the breast-fed infants in Incheon area consume almost adequately protein, Ca and P from the milk compared with RDA for Korean infants.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.281-284
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• 2007

The effect of Ca addition on the microstructure evolution and deformation behavior of AZ31 magnesium alloy produced by hot extrusion was investigated. For this purpose, Ca was added into AZ31 melts to the level of 0.7 and 2.0 wt.% Ca. Then, AZ31 base alloy and Ca modified AZ31 alloys were extruded at $383^{\circ}C$. Ca added alloys showed finer grain size and increased hardness value rather than AZ31 base alloy. After isothermal hot compression, the shape of tested specimen exhibited a noticeable anisotropy due to the crystallographic texture effect. The ratio of major and minor axes of ovality was not directly related to test condition and Ca amount. Flow stress level increases with the increase of Ca addition at temperature below $300^{\circ}C$ because of fine microstructure. However, at high temperature and low strain rate region ($400^{\circ}C$ and $10^{-3}s^{-1}$), reverse tendency was observed since main deformation mechanism changes from dislocation slip to grain boundary sliding or diffusional process at high temperature.

• 한국환경농학회지
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• 제30권3호
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• pp.229-233
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• 2011

BACKGROUND: Soil acidification, which is known to be one of the reasons of forest decline, is associated with decreases in exchangeable Ca and increases in Al concentration, leading to low Ca/Al ratio in soil solution. As tree rings are datable archives of environmental changes, Ca/Al ratios of annual growth ring may show decreasing pattern in accordance with the progress of soil acidification. This study was conducted to investigate Ca/Al pattern of Pinus densiflora tree ring in an attempt to test its usefulness as an indicator of historical soil acidification. METHODS AND RESULTS: Three P. densiflora tree disks were collected from P. densiflora forests in Jeonnam province, and soil samples (0-10, 10-20, and 20-30 cm in depth) were also collected from the tree locations. Soils were analyzed for pH and exchangeable Ca and Al concentrations, and Ca/Al was calculated. Annual growth rings formed between 1969 and 2007 were separated and analyzed for Ca/Al. Soil Ca/Al was positively (P<0.01) correlated with soil pH, suggesting that soil acidification decreased Ca while increasing Al availability, lowering Ca/Al in soil solution. The Ca/Al of tree rings also showed a decreasing pattern from 18.2 to 5.5 during the period, and this seemed to reflect historical acidification of the soils. CONCLUSION(s): The relationship between soil pH and Ca/Al and the decreasing pattern of Ca/Al of tree ring suggest that Ca/Al of tree ring needs to be considered as a proxy of the progress of soil acidification in P. densiflora forest in southern Korea.

• The Korean Journal of Physiology and Pharmacology
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• 제12권1호
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• pp.31-35
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• 2008

Lysophosphatidylcholine (LPC), a metabolite of membrane phospholipids by phospholipase $A_2$, has been considered responsible for the development of abnormal vascular reactivity during atherosclerosis. $Ca^{2+}$ influx was shown to be augmented in atherosclerotic artery which might be responsible for abnormal vascular reactivity. However, the mechanism underlying $Ca^{2+}$ influx change in atherosclerotic artery remains undetermined. The purpose of the present study was to examine the effects of LPC on L-type $Ca^{2+}$ current $(I_{Ca(L)})$ activity and to elucidate the mechanism of LPC-induced change of $I_{Ca(L)}$ in rabbit portal vein smooth muscle cells using whole cell patch clamp. Extracellular application of LPC increased $I_{Ca(L)}$ through whole test potentials, and this effect was readily reversed by washout. Steady state voltage dependency of activation or inactivation properties of $I_{Ca(L)}$ was not significantly changed by LPC. Staurosporine (100 nM) or chelerythrine $(3{\mu}M)$, which is a potent inhibitor of PKC, significantly decreased basal $I_{Ca(L)}$, and LPC-induced increase of $I_{Ca(L)}$ was significantly suppressed in the presence of PKC inhibitors. On the other hand, application of PMA, an activator of PKC, increased basal $I_{Ca(L)}$ significantly, and LPC-induced enhancement of $I_{Ca(L)}$ was abolished by pretreatment of the cells with PMA. These findings suggest that LPC increased $I_{Ca(L)}$ in vascular smooth muscle cells by a pathway that involves PKC, and that LPC-induced increase of $I_{Ca(L)}$ might be, at least in part, responsible for increased $Ca^{2+}$ influx in atherosclerotic artery.

• Corrosion Science and Technology
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• 제5권4호
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• pp.129-136
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• 2006

High temperature corrosion behavior of AISI-type 316L stainless steel for the MCFC(molten carbonate fuel cell) bipolar application was studied by immersion test and penetration attack method in anode environment ($650^{\circ}C$, $Li_2CO_3/K_2CO_3=62/38$ mol%, $H_2/CO_2=80/20$ vol%) without or with different $CaCO_3$ content. Not only immersion test method but also morphological observation of samples in the carbonate melts are adopted as experimental methods. With aid of the morphological observation of cross section of samples immersed in a carbonate melt was possible to obtain penetration attack. The concentration effect of $CaCO_3$ inhibitor was investigated in order to verify the optimum concentration for practical application in MCFC stack operation. The corrosion rate in the presence of $CaCO_3$ was proven to be decreased as a function of $CaCO_3$ concentration. The corrosion rate in the presence of $CaCO_3$ was measured with a value of 6.9 mpy which is 2.4 times lower than that of inhibitor-free electrolyte. The cross section microscopy revealed that the internal penetration by oxidation in molten carbonate is very severe. In this case, the attack was occurred not only dissolution loss in the electrolyte by corrosion reaction but also weight gain through oxide layer by internal penetration.

• 한국결정성장학회지
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• 제21권5호
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• pp.210-213
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• 2011

$P_2O_5$ 함량에 따른 $5Na_2O-36CaO-10TiO_2-xP_2O_5$으로 구성된 glass-ceramic을 다음과 같은 방법으로 제조하였다: 1) 1 N HCl 용액 내에서 $Ca_3(PO_4)_2$와 $NaTi_2(PO_4)_3$ 간의 $Ca_3(PO_4)_2$ 결정을 2일간 추출하여 제거함. 2) Ag($NO_3$) 용액에서 1일간 $Na^+$ 이온을 $Ag^+$ 이온으로 이온 교환시킴. Glass-ceramic의 합성 여부를 SEM 및 XRD를 이용하여 확인하였다. Staphylococus aureus를 이용한 박테리아 실험 결과 3시간 이후에는 완전하게 박테리아가 제거됨을 확인할 수 있었다.

• 생물정신의학
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• 제7권1호
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• pp.64-73
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• 2000

이 연구는 MAOA CA 반복 유전자다형성에 따라 알코올의존 환자에서 행동 및 성격특성 그리고 임상양상의 차이를 알아봄으로써 유전자형과 표현형과의 관계를 알아보기 위해 수행되었다. 이 연구 결과 임상양상에서 S군에 비해 L군의 임상양상이 보다 부정적인 양상을 보이고 있었다. 이는 MAOA CA 반복 유전자다형성이 음주양상을 변화시키는 역할을 할 가능성을 시사하고 있다. 그렇지만 이러한 영향이 유전자의 직접적인 인과관계로 설명하기는 어렵고 간접적이고 이차적인 영향에 따른 결과로 생각해 볼 수 있겠다. 또한, 행동특성에서 L군이 S군에 비해 전체적으로 공격성이 많았고 자기주장적 태도가 강했다. 그리고 MAOA CA 반복 유전자다형성의 대립유전자 길이가 자기주장적 태도와 상관관계가 있었으며 이러한 자기주장적 태도를 MAOA CA 반복 유전자다형성의 대립유전자 길이가 부분적으로 설명하고 있었고, 자기주장적 태도가 강한 환자의 경우 길이가 긴 대립유전자를 가질 가능성이 많았다. 공격성도 그 자체가 여러 가지 측면을 가지고 있는 복합적인 행동특성이기 때문에 전체 공격성을 어느 하나의 유전자만으로 설명할 수 있을 것으로 기대하는 것은 비현실적이다. 그렇지만 이 연구에서 자기주장적 태도는 분화된 공격성의 한 측면이어서 MAOA CA 반복 유전자다형성이 일부분이지만 설명을 할 수 있다는 것을 시사하고 있어, 연구자들은 이 연구가 향후 유전자형이 공격성 같은 표현형을 설명하는 연구들에 있어 기초자료가 될 수 있을 것으로 생각된다. 아직까지 MAOA CA 반복 유전자다형성과 MAOA 활성도와의 관계가 명확하지 않고 대사산물과의 관계도 설명이 어려운 실정이어서 향후 이에 대한 연구들이 필요하겠다.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제17권1호
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• pp.41-56
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• 2014

본 연구는 디지털 스토리텔링을 적용한 수학수업이 학생들의 수학적 의사소통불안에 어떠한 영향을 미치는지를 알아보기 위한 목적으로 실시되었다. 이를 위해 초등학교 6학년 학생을 대상으로 의사소통불안검사 결과가 유의한 차이가 없는 2개 학급을 선정하여 일반 스토리텔링과 디지털 스토리텔링을 각각 10주에 걸쳐 적용한 후 사후 의사소통불안검사를 통해 그 효과를 분석하였다. 연구 결과, 일반 스토리텔링을 적용한 학급은 사전 사후 의사소통불안검사 결과 유의미한 차이가 없었으나 디지털 스토리텔링을 적용한 학급은 의사소통불안 요소의 소집단과 관련하여 유의미한 차이가 있었다. 또한 일반 스토리텔링과 디지털 스토리텔링을 적용한 두 학급간의 사후 의사소통불안 검사결과에서는 수학시간과 소집단의 요소에서 유의미한 차이가 있었다. 이러한 결과를 통해 디지털 스토리텔링의 적용이 초등학교 6학년 학생들의 수학시간의 발표, 소집단에 대한 의사소통불안을 줄이는데 도움이 된다는 것을 알 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.375-378
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• 2005

In this study, calcium chloride($CaCl_2$), sodium chloride (NaCl), organic acids-containing deicer(NS 40, NS 100), mixed deicier($NaCl\;70\%\;+\;CaCl_{2}\;30\%,\;NS\;40\;70\%\;+\;CaCl_{2}\;30\%,\;NaCl\;70\%\;+\;NS\;40\;30\%,\;NS\;40\;70\%\;+\;NaCl\;30\%$) is investigated based on the laboratory test for freez-thaw resistance of concrete and corrosion of metal. As a test results, in case of the use chloride-containing deicier in area that concrete structures has subjected to freez-thaw reaction in winter season, it showed desirable method that use deicing chemicals mixed with optimum ratio rather than use one deicing chemicals when is consider to deicing performance and effects, corrosion of steel materials, freez-thaw resistance of concrete. When use various deicing chemicals mixed, NS40($70\%$)+Calcium chloride($30\%$) showed the best effective method.

• 한국세라믹학회지
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• 제33권3호
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• pp.277-284
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• 1996

The water test results indicated that the impurities had detrimetal effect on the wear resistance of silicon nitride and the effects were getting severe as the temperature increased. Especially when Ca existed as an impurity the detrimental effects was the most severe. These results were resulted from the fact that impurities lowered the mechanical properties of the grain boundary phase of silicon nitride. The wear test results of glass/glass-ceramic specimens having a similar composition to the grain boundary phase of silicon nitride revea-led that the specimen containing CaO showed the lowest wear resistance. The existence of Fe and Ca at the grain boundary phase assisted forming a grain boundary phase with relatively low refractoriness. Therefore at a given wear condition the removal of deformed layer would be easier. The results showed that the glass phases could be modified by heat-treatment and this modification improved tribological characteristics of the silicon nitride.