• 한국건축시공학회지
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• 제14권1호
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• pp.68-75
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• 2014

In order to increase the integrity of the wellbore which is used to prevent the leakage of supercritical $CO_2$, it is necessary to develop a concrete that is strongly resistant to carbonation. In an environment where the concentration of $CO_2$ is exceptionally high, $Ca^{2+}$ ion concentration in pore solution of Portland cement concrete will drop significantly due to the rapid consumption of calcium hydroxide, which decreases the stability of the calcium silicate hydrate. In this research, calcium phosphates were used to modify Portland cement system in order to produce hydroxyapatite, a hydration product that is strongly resistant to carbonation under such an environment. According to the experimental results, calcium phosphates reacted with Portland cement to form hydroxyapatite. The formation of hydroxyapatite was verified using X-ray diffraction analyses with selective extraction techniques. When using dicalcium phosphate dihydrate and tricalcium phosphate, the 28-day compressive strength was lower than that of plain cement paste. However, the specimen with monocalcium phosphate monohydrate showed equivalent strength to that of plain cement paste.

• 한국토양비료학회지
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• 제46권5호
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• pp.308-312
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• 2013

The monitoring of chemical dynamic changes in controlled horticultural lands is very important for agricultural sustainability. Field monitoring was performed to evaluate the soil chemical properties of 200 controlled horticultural soil samples in Gyeongnam province every 4 years from 2000 to 2012. Soil chemical properties such as pH, amount of organic matter, available phosphate, nitrate nitrogen, and exchangeable potassium, calcium, magnesium, and sodium were analyzed. The amount of exchangeable calcium and soil pH were significantly higher in 2012 than in 2000. In 2012, the frequency distribution for values of pH, organic matter, available phosphate, and exchangeable potassium, calcium, and magnesium that were within the optimum range was 16.0%, 22.5%, 11.5%, 3.5%, 2.5%, and 5.0%, respectively. Especially, available phosphate and exchangeable calcium were excess level with portions of 76.0% and 96.5%, respectively. These results indicated that a balanced management of soil chemical properties can reduce the amount of fertilizer applied for sustainable agriculture in controlled horticultural lands.

• 한국세라믹학회지
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• 제47권3호
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• pp.244-248
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• 2010

Porous calcium phosphates were successfully fabricated by using a cuttlefish bone. The cuttlefish bone, which is composed of $CaCO_3$, showed a special porous microstructure containing uniform-sized voids. In this study, the pre-forms infiltrated distilled phosphoric acid were sintered at $1200^{\circ}C$ in an air atmosphere. The porous microstructure of the pre-forms was kept their original pattern after sintering with a synthesis of calcium phosphate. The obtained porous calcium phosphate, sintered at $1200^{\circ}C$ for 3 h at 17% concentration of phosphoric acid, showed uniform open pores of 150 ${\mu}m$ in size and $\beta$-TCP phase in the XRD patterns. Above 16% concentration, CaO phase, derived from the decomposition of $CaCO_3$, decreased gradually in the sintered samples, and the measured Ca/P ratios of the samples prepared from 16% and 18% concentration were 1.67 and 1.43, which are close to stoichiometric HA (1.66) and $\beta$-TCP (1.50).

• 한국재료학회지
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• 제13권4호
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• pp.246-250
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• 2003

Calcium phosphate was prepared by chemical reaction formula using Oyster shells and $H_3$$PO_4$solutions. After added to 0.1 M∼0.9$ M H_3$$PO_4$ solution for oyster shell, prepared powders were investigated for heating properties and formation phase with heat treatment temperatures. As the results of XRD analysis of heated powders at $500^{\circ}C$∼$1200^{\circ}C$,$ CaCO_3$ phases were observed at the temperature of below 900 TEX>$^{\circ}C$ and in the condition of 0.1 M∼0.9 M $H_3$$PO_4$ solutions. However, $CaCO_3$, $CaPO_3$(OH) and $Ca_3$($PO_4$)$_2$ phases were appeared at the temperature range between $500∼900^{\circ}C$ and in the solution of 0.7 M to 0.9 M $H_3$$PO_4$. $Ca_{ 5}$($PO_4$)$_3$(OH) and CaO phases due to the decarbonation of oyster shells($CaCO_3$) were appeared at above $1000^{\circ}C$ and in the solution of below 0.5 M $H_3$X$PO_4$. However in the case of above 0.7 M $H_3$$H_4$ solutions, $Ca_{5}$ ($PO_4$)$_3$(OH) was decomposed into $Ca_3$($PO_4$)$_2$ at more higher 100$0^{\circ}C$. Thus $Ca_3$(X$Ca_4$)$_2$ phases were appeared at higher than 100$0^{\circ}C$.

• 한국결정성장학회지
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• 제22권2호
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• pp.99-104
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• 2012

BCP(biphasic calcium phosphate) 분말을 제조하기 위하여 $Ca(NO_3)_2{\cdot}4H_2O$, $(NH_4)_2HPO_4$를 출발 물질로 공침법(co-precipitation process)을 이용하여 합성하였다. 합성된 분말의 열처리 전 후의 HAp(Hydroxyapatite)/${\beta}$-TCP(${\beta}$-Tricalcium phosphate) 결정상 비율 및 분광학적 특성을 XRD 및 FT-IR를 이용하여 분석하였다. BCP 분말의 생체활성 거동을 평가하기 위하여 Hanks' Balanced Salt Solution(HBSS)에 침적시켜 시간에 따라 형상, 이온농도의 변화 및 결정상을 분석한 결과 낮은 결정화도의 HAp가 생성됨을 확인하였다. BCP분말의 세포독성 평가에서도 대조군에 비하여 세포성장률이 우수함을 관찰하였다.

• 농업과학연구
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• 제3권2호
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• pp.139-144
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• 1976

신개간지토양(新開墾地土攘)의 합리적(合理的)인 지력증진(地力增進) 개선방안(改善方案)을 구명(究明)하기 위(爲)하여 7종(種)의 토양개량방법(土壤改良方法)을 처리(處理)하고 대두(大豆)을 재배(栽培)하였던바 그결과를 요약(要約)하면 다음과 같다. 신개간지(新開墾地) 토양(土攘)에서는 pH가 낮고 유기물(有機物)과 인산(燐酸)은 물론 석회(石灰) 마그네슘등(等)의 염기가 부족(不足)하였다. 석회(石灰)와 용성인비(熔成燐肥)는 토양산도(土壤酸度)의 교정효과(校訂效果)가 컷으며 유기물(有機物)의 증가(增加)에 대해서는 퇴비(堆肥)의 효과(效果)가 가장 큰 것과 퇴비(堆肥)와 용성인비(熔成燐肥)는 토양중(土壤中)의 칼슘함량(含量)을 증가(增加)시키는 효과(效果)가 컷으며 석회(石灰) 용성인비(熔成燐肥) 퇴비(堆肥) 및 심경(深耕)모드가 토양중(土壤中)의 고토함량(苦土含量)을 현저(顯著)히 증가(增加)시켰다. 그리고 퇴비(堆肥)는 토양중(土壤中)의 가리함량(加里含量)을 증가(增加) 시키는 효과(效果)가 현저(顯著)하다. 석회용성인비(石灰熔成燐肥) 및 퇴비(堆肥)는 식물체내의 마그네슘함량(含量)의 증가(增加)에 현저(顯著)한 효과(效果)를 나타내었으며 석회(石灰) 및 용성인비(熔成燐肥)는 각각(各各) 종실중(種實重)의 증효효과(增效效果)가 컸다. 3요소(要素) 퇴비(堆肥) 및 석회시용(石灰施用)과 동시(同時)에 심경(深耕)을 실시(實施)한 구(區)에서 최고(最高)의 종실수량(種實收量)을 보였다. 종실수량(種實收量)은 토양산도(土壤酸度), 토양중(土壤中)의 유기물(有機物) 고토함량(苦土含量) 그리고 식물체내의 고토함량(苦土含量)과 현저(顯著)한 정(正)의 상관관계(相關關係)를 나타내었다.

• 생명과학회지
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• 제14권1호
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• pp.174-179
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• 2004

난용성 인산염을 가용화시키는 균주를 염류직접 및 인산과다처리 재배지로부터 다수 분리하였다. 다수의 균들은 대다수가 tri-calcium phosphate의 가용화능을 가진 균주들이 었고 hydroxyapacte의 가용화능을 가진 균주가 소수있었다. 본 연구는 hydroxyapatite 가용화능을 가진 분리균주 Klebsiella sp. DA7l-1의 배양특성에 따른 난용성 인산염(hydroxyapatite, tri-calcium phosphate, aluminium phosphate), pH변화 및 배양온도에 따른 인산염의 가용화특성 등을 조사하였다 인산 가용화능은 유기산 생성과 밀접한 관련이 있다고 많이 보고되어 졌지만 아직 pH저하에 따른 인산 가용화의 정확한 기작은 확인이 되지않은 상태이며 배지내의 pH저하는 균주의 유기산 생성에 따른 것으로 사료되어진다. 조사한 결과 배양시간 12 이후부터 pH 저하를 나타냈으며 pH저하는 균생육에 영향을 미치지 않는 범위내에서 이루어졌으며 pH가 저하된 상태의 배지 조건에서 균의 생육이 계속될수록 인산가용화능이 높게 이루어졌다. 또한 DA7l-1은 초기 pH에 영향을 크게 받지 않았으며 일반 토양의 온도와 비슷한 조건의 온도에서도 가용화 능력이 뛰어난 것으로 나타났다.

• 약학회지
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• 제36권6호
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• pp.513-517
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• 1992

The effect of solubility and hygroscopicity of some tablet diluents on the disintegration of enzyme tablets was investigated. Tablets were prepared by direct compression method using sodium starch glycolate, crospovidone, croscarmellose sodium and low-substituted hydroxypropyl cellulose as super disintegrants. Lactose, dextrose, sucrose, sorbitol and calcium phosphate dibasic were selected as typical diluents in this study. They were different in solubility (sucrose, sorbitol>dextrose>dextrose>lactose>calcium phosphate dibasic) and hygroscopicity (sorbitol>sucrose>dextrose>caicium phosphate dibasic, lactose). The disintegrants accelerated differently the disintegration of the tablets prepared with different diluents in the decreasing order of calcium phosphate dibasic>lactose>dextrose>sucrose and sorbitol. These results indicate highly soluble and/or hygroscopic diluents decrease the efficiencies of super disintegrants in the enzyme tablets.

• 농업과학연구
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• 제38권3호
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• pp.459-464
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• 2011

A simplified model for the colloidal calcium phosphate (CCP) nanocluster was developed from an active role of phosphate in the precipitation of casein (CN)/Ca mixtures and the composition of casein micelles (CM). The possible shape of the CCP nanocluster was selected as a tetrahedron, and we estimated that 4 CN molecules were involved in crosslinking a single CCP nanocluster. Similar values were obtained for the number of CN molecules involved in stabilizing the nanocluster when the number of CNs attached onto each nanocluster surface was deduced from the composition of CM. If one phosphoserine cluster consisted of 3 phosphoserine residues, the theoretical molecular weight and volume for the nanocluster were estimated to be 4,898 g/mol and 2.88 $nm^3$, respectively. It was also shown that the position of Ca present in our model were reasonably located to accommodate the serine phosphate in CN molecule.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.161-162
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• 2012