• 한국세라믹학회지
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• 제39권2호
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• pp.194-198
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• 2002

$K_2O{\cdot}CaO{\cdot}P_2O_5$를 기본조성으로 하여 용융법에 의해 유리 형성범위를 정의하고자 하였다. TG-DTA와 DSC를 이용하여 열적 특성을 관찰하고자 하였으며, FT-IR과 Raman Spectroscopy를 이용하여 구조를 분석하였다. $K_2O{\cdot}CaO{\cdot}P_2O_5$의 함량이 증가함에 따라 유리전이온도 및 연화온도는 감소하였다. $K_2O{\cdot}CaO{\cdot}P_2O_5$ 유리의 기본 구조는 이웃한 구조와 상호 결합을 위한 $PO_2$와 $PO_4^{3-}$ 구조와 유리의 골격구조를 이루는 P-O-P 결합이며, CaO의 함량이 증가함에 따라, 유리내의 P-O-P의 결합력은 점차적으로 증가하였으며, $PO_2$와 $PO_4^{3-}$의 intensity는 점차적으로 감소하였다.

• 한국세라믹학회지
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• 제27권8호
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• pp.979-990
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• 1990

The possible use of bioglass as implant materials is due to its biocompatibility to human body. Even if many animal studies for the bioglasses have been performed, their structures and physical properties are not fully understood. In the present work, several investigations such as Raman spectroscopic analysis, density, thermal expansion coefficient, softening temperature, and refractive index measurement were carried out to find the structures and physical properties of bioglasses, where MgO is substituted for CaO in bioglass composition (46.1%SiO2, 24.4%Na2O, 26.9%CaO, 2.6%P2O5 ; mole%). Hydroxyapatite formation on the glass surface reacted in Tris-buffer solution was also examined. When CaO was replaced by MgO, nonbridging oxygen in glass structuer was diminished but the degree of disorder increased. Thermal expansion and softening properties showed the mixed oxide effect. Hydroxyapatite were formed on the surface of 0~11mole% of MgO containing bioglasses, and the thickness of SiO2-rich layer as well as hydroxyapatite layer were unchanged with MgO content. However, the hydroxyapatite was not formed on the surface of the bioglasses containing over 11 mole percent MgO, even if the glasses were reacted for long period.

• 전자공학회논문지A
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• 제29A권10호
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• pp.17-23
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• 1992

A ($Pb_{1-x}Ca_{x})ZrO_{3}$ system which has a high dielectric constant, low dielectric loss and temperature coefficient was investigated. For sintering temperatures above 1350$^{\circ}C$ the microstructures of sintered bodies were unchanged regardless of the amount of CaO. The dielectric constant and dielectric loss decreased and the temperature coefficient varied from positive to negative with the increasing amount of CaO. For the CaO content of 0.37, i.e. ($Pb_{0.63}Ca_{0.37})ZrO_{3}$, the ceramic showed very good dielectric properties such as ${\varepsilon}_1$=100, Q > 1200 at 3GHz, and T$_f$=$\pm$3ppm/$^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.42-45
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• 2001

$(Ba_{0.6}Sr_{0.4}Ca_{x})TiO_{3}+yZrO_{2}$ wt% (x=0.10, 0.15, 0.20, y=0.5~3.0) specimens were fabricated by the mixed-oxide method and then the structural and dielectric properties as a function of the composition ratio and $ZrO_2$ contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The Curie temperature and the dielectric constant at room temperature decreased with increasing the Ca/Ba composition ratio and $ZrO_2$ content. The BSCT(50/40/10) specimens showed the excellent tunability property. And the tunability were increased with increasing the contents of $ZrO_2$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.42-45
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• 2001

(Ba$_{0.6-x}$Sr$_{0.4}$Ca$_{x}$)TiO$_3$+yZrO$_2$wt% (x=1.10, 0.15, 0.20, y=0.5~3.0) specimens were fabricated by the mixed and ZrO$_2$ contents were studied. All BSCT specimens contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The Curie temperature and the dielectric constant at room temperature decreased with increasing the Ca/Ba composition ratio and ZrO$_2$ content. The BSCT(50/40/10) specimens showed the excellent tunability property. And the tunability were increased with increasing the contents of ZrO$_2$./TEX>.

• 자원리싸이클링
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• 제11권5호
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• pp.21-23
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• 2002

A new process based on the co-precipitation method was developed fer removing harmful impurities during Mn-Zn ferrite production such as $SiO_2$ and P from waste pickle liquor. By this process a final result of less than 100 ppm of $SiO_2$ and less than 10 ppm of P content in the ferric oxide is easily attained. Though Ca cannot be removed by this process, water rinsing of the ferric oxide is effective fer reducing Ca content to less than 100 pm. For further purification, the origins of each impurity must be investigated and then taken away.

• Applied Biological Chemistry
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• 제19권1호
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• pp.31-35
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• 1976

과맥 15개(個) 품종(品種) 또는 선발조건(選拔係統)(3개(個) 도원(道院)에서 재배(栽培)한 것)에 대(對)하여 단백질(蛋白質), 탄수화물(炭水化物) 및 P, K, Ca, Mg를 분석(分析)하고 염색법(染色法)과 Biuret에 의(依)한 단백질(蛋白質) 검정(檢定)을 하였으며 이들 상호간(相互間)의 상관관계(相關關係)를 분석(分析)한 결과(結果)는 다음과 같다. 1. 단백질함량(蛋白質含量)은 평균(平均) 7.67%(최대(最大)백동 10.3, 최소(最少)방주 6.0%)로 대맥(大麥)보다 낮았으며 염색법(染色法)(DBC)과는 r=-0.769, Biuret과는 0.616으로 1%에서 유의성(有意性)을 보였다. 2. 단백질함량(蛋白質含量)은 $P_2O_5$와 r=0.607, MgO와 0.498로 각각 1% 및 5%에서 유의성(有意性)을 보였다. 3. 방사선(放射線) 육종(育種) 계열(係列)의 단백함량(蛋白含量)은 최대(最大) 8.40%, 최소(最少) 6.75%로 큰 차이를 보였다. 4. 과맥은 대맥(大麥)보다 탄수화물(炭水化物)이 적은 편이나 무기성분(無機成分) 함량(含量)은 높은 편이다. 5. Ca는 K와 r=-0.560의 1%에서 유의상관(有意相關)을 보여 곡실(穀實)에로의 전류(轉流) 또는 흡수(吸收)에서의 길항적(拮抗的) 관계(關係)가 있는 것 같다. 6. 탄수화물함량(炭水化物含量)은 유의성(有意性)은 없으나 단백질함량(蛋白質含量)과 최대부상관(最大負相關)을 보였다. 7. 고단백품종(高蛋白品種)(백동)보다 저단백품종(低蛋白品種)(방주)은 시비구(施肥區)(16%)에서나 무비구(無肥區)(47%)에서 수량(收量)이 높았다.

• 한국결정성장학회지
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• 제8권3호
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• pp.503-507
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• 1998

마이크로파 유전체로 응용되는 $xCaTiO_3-La(Zn_{1/2}Ti_{1/2})O_3$계의 소결시 고용조성 변화(x=0.4-0.6) 및 소결거동에 따른 유전특성에 조사하였다. 소결밀도가 감소함에 따라 유전상수는 감소하였으며 품질계수(Q)는 증가하다 일정한 값을 유지하였다. 고용체형의 경우 유전상수는 $CaTiO_3$조성 증가에 따라 증가하였다. $0.5\;CaTIO_3\;0.5\;La(Zn_{1/2}Ti_{1/2})O_3$의 경우 유전상수 48, 온도계수는 $-1ppm/^{\circ}C$를 나타내었다.

• 한국환경과학회지
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• 제11권12호
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• pp.1291-1298
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• 2002

To utilize coastal aquaculture ground bottom sediment in which concentrations of harmful pollutants are low and organic content is high as an organic fertilizer alkaline stabilizers such as CaO, Oyster shell, Mg(OH)$_2$ were added to the bottom sediment organic additives of livestock or food wastes. Nutritive qualities of crude fertilizers were measured to examine effects of alkaline stabilizers and organic waste additions. The Mg(OH)$_2$-added crude fertilizer had significantly lower total carbon(T-C) and nitrogen(T-N) content, reflecting the dilution effect due to great amount of Mg(OH)$_2$ addition. However, the addition of oyster shell had no significant effect on the T-C and T-N content of the fertilizer. $P_2O_5$ and $K_2$O content was considerably higher in the mixed sample of aquaculture ground bottom sediments and livestock wastes than in the mixture of the sediments and food wastes, resulting from higher $P_2O_5$ and $K_2$O content in livestock wastes. Addition of Mg(OH)$_2$ increased the content of MgO In the crude fertilizer but significantly reduced the content of other nutritive elements such as $P_2O_5$, $K_2$O and CaO. Addition of oyster shell as an alkaline stabilizer seemed to have the advantage of saving time and expenses far dryness due to its role as a modulator of water content. Moreover, additions of effect Mg(OH)$_2$ decreased the concentrations of heavy metals in the fertilizer by the dilution while additions of oyster shell had no influence on heavy metal concentrations in the fertilizer.

• 한국세라믹학회지
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• 제49권2호
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• pp.146-150
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• 2012

The effects of $Al_2O_3$ on the crystallization behavior of glass compositions in the $Na_2O$-CaO-$SiO_2$ system were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effect of $Al_2O_3$ content on the mechanical properties, density, phase formation, and microstructures of $Na_2O$-CaO-$P_2O_5$-$SiO_2$ glass ceramics were studied. The thermal parameters of each glass were studied by DTA. The density of the glass ceramic samples was measured by Archimedes' method. It was found that the glass-ceramic containing 2.0 molar percent $Al_2O_3$ had desirable sintering behavior and reached an acceptable density. Phase investigation and micro-structural analysis were performed by XRD and SEM, respectively.