• 한국재료학회지
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• 제9권6호
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• pp.547-550
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• 1999

Optical and electrical properties of MgO-CaO films as a protective layer for AC plasma display panel were studied. When the [(CaO/(MgO+CaO)] ratio of evaporation starting materials was optimum composition, 0.1, firing voltage and memory margin of the film were 176V and 0.5, respectively. When [CaO/(CaO+MgO)] was 0, 0.1 and 0.2, memory margin was 0.39, 0.5 and 0.41, respectively, and surface roughness of films was $27.7\AA$, $21.1\AA$ and $40.3\AA$, respectively. It was thought that memory margin had a reverse-relation with surface roughness. The density of film was calculated by measuring the refractive index of film. The density of MgO film was 3.21g/㎤ and the density of film, when [CaO/(CaO+MgO)] was 0.1, was 3.632g/㎤. The mixture of MgO-CaO films showed a good transmittance property in the visual range.

• 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.

• Journal of Advanced Marine Engineering and Technology
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• 제28권6호
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• pp.1000-1009
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• 2004

The environment friendly calcareous deposit films were formed on steel plates by electrodeposition technique in natural seawater and synthetic solutions such as dissolved $\textrm{Mg}^{2+}$ and $\textrm{Ca}^{2+}$ ions at various potential conditions. The influence of potential conditions on composition ratio, structure and morphology of the electrodeposited films were investigated by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray diffractor (XRD). Accordingly, this study was provided a better understanding of the composition between the growth of $\textrm{Mg(OH)}_2$ and that of $\textrm{CaCO}_3$ during the formation of calcareous deposit films on steel substrate under cathodically electrodeposition in synthetic and natural seawater. The results showed that the formation of good overall calcareous deposited film in seawater can be achieved by controlling the Ca/Mg ratio according to interfacial pH with the effective use of the electro deposition technique.

• 생명과학회지
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• 제11권2호
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• pp.153-158
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• 2001

To investigate the effects of soil acidification on growth of Impatiens balsamina L. plants were transplanted to acidified soils with H$_2$SO$_4$ solution. The concentrations of soluble Ca, Mg, K, Al and Mn in the acidified soils increased with increment of H$^{+}$ addition to the soil. In both species, the plant height and root length were inhibited by soil acidification, showing much severer inhibition in Impatiens balsamina L. than in Tagetes patula L., As the soil pH decreases, the growth of underground parts decreased greatly than that of above ground parts in both species. Total dry weight decreased with increased Al concentration as well as lowered soil pH in both plants. There was a strong positive correlation between relative total dry weight and molar (Ca+Mg+K) / Al ratio of the soil. The results suggest that molar(Ca+Mg+K)/ Al ratio of the soil may be useful indicator for assessing the critical load of acid deposition in herb species.s.

• 자연과학논문집
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• 제8권2호
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• pp.175-179
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• 1996

수확 후 '십장랑'과실의 당도와 산함량은 저장기간이 경과할수록 과실의 크기와는 관계없이 감소되었으며, 과실경도도 감소되었는데 소과보다 대과의 감소솔이 컸다. 과실의 에틸렌발생은 저장기간 중 증가되었고 호흡량은 수확 후 2주와 6주에 두 번의 상승이 있었다. 과실의 칼슘과 마그네슘함량은 과피부분이 가장 높고 과심이 그 다음이며 과육이 가장 낮았으며, 특히 칼슘함량은 외부의 과육이 내부의 과육보다 낮았고 마그네슘은 중간부위의 과육이 낮았다. Ca/Mg 율은 과심주위의 과육이 높았고 K/Ca 율은 외부과육이 높았다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.79-82
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• 2002

$(Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3$ + ywt% MgO (x=0.10, 0.15, 0.20, y=0.0~3.0) ceramics were fabricated by the conventional solid-state reaction, and their structural and dielectric properties were investigated with variation of composition ratio and MgO doping content. A second phase, representative of MgO, appears in 3wt% MgO-doped BSCT specimens. Average grain sizes decreased with increasing amounts of MgO, and the BSCT(40/40/20) specimens doped with 3wt% MgO showed a value of $9.3{\mu}m$. The Curie temperature and relative dielectric constant at room temperature were decreased with increasing MgO doping content and Ca composition ratio. The relative dielectric constant was non-linearly decreased as the field strength is increased. The tunability was increased with decreasing a Ca content and the BSCT(50/40/10) specimen doped with 1.0wt% MgO content showed the highest value of 6.4% at 5kV/cm.

• 한국세라믹학회지
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• 제39권3호
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• pp.222-225
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• 2002

Microwave dielectric properties of the layered and functionally graded materials (FGMs) of $Mg_{0.93}Ca_{0.07}TiO_3$ (MCT) and $(Ca_{0.3}Li_{0.14}Sm_{0.42})TiO_3$(CLST) were investigated as a function of the volume ratio of two components. Dielectric constant was decreased with an increase of the volume ratio of MCT which had a lower dielectric constant thant CLST. For the layered FGMs specimens, the difference of thermal expansion coefficients between two components induced thermal strain to dielectric layers, which was confirmed by the plot of ${\Delta}$k (X-ray diffraction peak width0 versus k (scattering vector) using the double-peak Lorentzian function, f(x). Quality factor of the specimens was affected by the thermal strain of dielectric layer, especially MCT layer. For the specimen with the volume ratio of MCT/CLST = 2, the qulaity factor of the specimen showed a minimum value due to the maximum thermal strain fo MCT layer.

• 한국진공학회지
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• 제8권1호
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• pp.70-74
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• 1999

Plasma Display Panel(PDP)에서 보호막 물질로 사용중인 MgO 특성을 개선하기 위하여 본 연구에서는 MgO-CaO 박막을 전자빔 증착법으로 제조하였다. MgO 최대 증착속도는 1025 $\AA$/min이었으며 CaO 첨가비가 증가함에 따라 증착속도는 감소하였고, XRD 패턴은 전체적으로 낮은 2$\theta$각 방향으로 이동하였다. MgO 대한 CaO의 최대 고용도는 0.13이다. 최적전압특성을 나타낸 조성은 Mg 47.1 at%, Ca 1.3 at%, O 51.6 at%이었으며 이때 방전개시전압은 176 V, 메모리마진은 0.5였으며 증착속도는 515$\AA$/min이었다.

• 한국건설순환자원학회논문집
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• 제8권4호
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• pp.404-412
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• 2020

본 연구는 무기질 재료인 Calcium sulfoaluminate(CSA), Crystalline admixture(CA) 그리고 Magnesium oxide(MgO)가 포함된 시멘트 모르타르의 물성 및 자기치유성능을 조사하였다. 자기치유성능을 분석하기 위해 모르타르 강도시험, 물투과성 실험을 실시하였으며, 다양한 균열폭 변화는 디지털 광학현미경을 사용하여 측정하였다. 자기치유를 통해 생성된 수화물에 대해서는 X-ray powder diffraction, Thermogravimetry를 통한 성분분석을 실시하였다. 분석결과 CA치환량이 증가 할수록 압축 및 휨 강도는 증가하였다. 하지만 MgO치환 시에는 오히려 CA치환량이 증가 할수록 압축 및 휨 강도는 감소하였다. 회복된 균열부에 생성된 치유물질은 Ca(OH)2, MgCO3, CaCO3으로 확인되었다. CaCO3은 균열부에 생성된 주요 치유 성분으로 나타났으며, Ca(OH)2, MgCO3보다 높은비율을 차지하고 있는 것으로 확인 되었다. 또한, 물 투과성과 균열폭 결과를 통한 최적의 배합은 CSA 8% + CA 1% + MgO 2.5%으로 나타났다.

• Journal of Nutrition and Health
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• 제12권1호
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• pp.17-22
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• 1979

This study was designed to investigate calcium intake, the ratio of Ca intake versus R.D.A. (Recommended Dietary Allowance) for Ca, apparent Ca absorption rate, and Ca sources of food among school children in Korea. One hundred school children aged from 6 to 12 years were engaged in this study; 33 subjects were from farming village neal Seoul, and 67 children from big cities. Two days of food consumption records and feces collections of the subjects had been done from April 1978 to June 1978. The following observations were made in the present study; 1) Average Ca intake of total subjects was $457{\pm}214mg$ which is only 76% of R.D.A. for Ca. Calcium intakes for farming village children was higher than that of the subjects from big cities (p<0.05). 2) Survey on the food sources of Ca revealed that the amount of Ca taken from cereals averaged 120 mg (22.3% of total Ca intake), 111 mg (24.3%) from fruits and vegetables, 176 mg (38.5%) from meats, poultry, fishes and eggs, and only 68 mg (14.9%) was supplied by milk and milk products. From the data collected, following observations were made; a) No significant difference in Ca intake from cereals was found between village children and the ones from big cities. b) Average Ca intake from fruits and vegetables of city children was significantly higher than that of village children (p<0.005) with the values for 133 mg for the former and 64 mg for the latter. c) For the group of meats, poultry, fishes and eggs, significantly higher intake was found in village subjects than city children (p<0.0005) with the values of 340 mg and 95 mg, respectively. d) Contrarily, Ca intake from milk and milk products was significantly (p<0.0005) much higher in the city children (98 mg) than village ones (7 mg). 3) Apparent Ca absorption rate of total subjects was 51%; 44% for village children and 54% for city children. Ca absorption rate tends to be higher in the city subjects but no significant difference was noted.