• 대한화학회지
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• 제9권1호
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• pp.49-54
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• 1965

One of the difficult and time consuming problems in the production of magnesia from sea water is a settling rate of magnesium hydroxide. In this experiments, authors attempted to accelerate its settling rate by addition of various sedimenting agents as C.M.C., Separan and Starch, and sought for optimum calcination temperature for domestic dolomite, as alkali source, mole ratio of dolomite milk to bittern. It is observed through experiments that the small amounts of sedimenting agents, C.M.C., Separan, starch, 20 mg/l, 40 mg/l, 400mg/l, respectively increase the settling rate of magnesium hydroxide by 8 times or more. The following conditions resulted in good yield of magnesium hydroxide from sea water with relatively tolerable calcium oxide contaminated for the magnesium clinker. Calcinating temperature, $1,100{\sim}1,200^{\circ}C$, mole ratio of 10% dolomite milk to magnesium salts in sea water or bittern, 1. 2 : 1.

• 대한치과의사협회지
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• 제54권8호
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• pp.658-665
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• 2016

Treatment of immature permanent teeth with irreversibly damaged pulp has been challenging in dental practice because of the lack of apical constriction, thin dentinal walls, and short roots. This may lead to the extrusion of filling materials, and fracture of the root due to its more fragile feature during shaping of the root canal. Apexification with calcium hydroxide or MTA is one of the treatment options for these cases. Although favorable results of apexification have been reported, these treatment procedures do not guarantee the increase of root length and/or width even after a long term period. Thus, treated teeth are still prone to fractures. Recently, pulp revascularization has been proposed as an alternative treatment for immature teeth with necrotic pulp and periapical pathosis. Pulp revascularization allows the stimulation of the apical development and the root maturation. There have been many treatment protocols using various materials such as antibiotics and calcium hydroxide medicament. In this case report, literature review about pulp revascularization and two related cases are presented.

• 동의생리병리학회지
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• 제18권4호
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• pp.1098-1101
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• 2004

This study was carried out to investigate the solubility of the ingredients of the kidney stone in the solution of the traditional oriental medicines. Calcium hydroxide, apatite and uric acid were chosen as the ingredients of the kidney stone. Plantaginis Semen, Lysimachiae Herba, Saururi Herba seu Rhizoma, Imperatae Rhizoma, Allium tuberosum Rottler were studied as the oriental medicines for the kidney stone. Calcium hydroxide had showed the very good solubility in the solution of Imperatae Rhizoma, the apatite had showed the good solubility in the solutions of Saururi Herba seu Rhizoma and Allium tuberosum Rottler. Uric acid had showed the mild solubility in the solution of Lysimachiae Herba and Saururi Herba seu Rhizoma.

• Computers and Concrete
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• 제13권1호
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• pp.97-115
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• 2014

Silica fume is a by-product of induction arc furnaces and has long been used as a mineral admixture to produce high-strength, high-performance concrete. Due to the pozzolanic reaction between calcium hydroxide and silica fume, compared with that of Portland cement, the hydration of concrete containing silica fume is much more complex. In this paper, by considering the production of calcium hydroxide in cement hydration and its consumption in the pozzolanic reaction, a numerical model is proposed to simulate the hydration of concrete containing silica fume. The heat evolution rate of silica fume concrete is determined from the contribution of cement hydration and the pozzolanic reaction. Furthermore, the temperature distribution and temperature history in hardening blended concrete are evaluated based on the degree of hydration of the cement and the mineral admixtures. The proposed model is verified through experimental data on concrete with different water-to-cement ratios and mineral admixture substitution ratios.

• Advances in environmental research
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• 제4권3호
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• pp.183-196
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• 2015

Migration of leachate generated through embankment of construction waste soil (CWS) in low-lying areas was studied through physical and chemical analysis. A leachate solution containing soluble cations from CWS was found to have a pH above 9.0. To determine the distribution coefficients in the alkali solution, column and migration tests were conducted in the laboratory. The physical and chemical properties of CWS satisfied environmental soil criteria; however, the pH was high. The effective diffusion coefficients for CWS ions fell within the range of $0.725-3.3{\times}10^{-6}cm^2/s$. Properties of pore water and the amount of undissolved gas in pore water influenced advection-diffusion behavior. Contaminants migrating from CWS exhibited time-dependent concentration profiles and an advective component of transport. Thus, the transport equations for CWS contaminant concentrations satisfied the differential equations in accordance with Fick's 2nd law. Therefore, the migration of the contaminant plume when the landfilling CWS reaches water table can be predicted based on pH using the effective diffusion coefficient determined in a laboratory test.

• Journal of Pharmaceutical Investigation
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• 제3권1_2호
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• pp.34-50
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• 1973

There are many reports on the stability of drugs in powders and tablets. The stabilities of ascorbic acid in the antacid preparations, such as calcium carbonate, magnesium carbonate, magnesium trisilicate, magnesium alumino silicate, and dried aluminum hydroxide gel under various humidities were examined. From the result of the experiment, it was assumed that the concentration of ascorbic acid, the amount of water-vapor sorption, and the physical character of the antacid ingredients were the main factors, influencing the degradation of ascorbic acid. The ascorbic acid, mixed with carbonates, such as calcium carbonate, was degradaded rapidly, while the preparation with dried aluminum hydroxide gel was slightly degraded after 10 days. A 2% ascorbic acid in the prepation was rapidly degraded than 10% ascorbic acid in the preparation.

• 한국세라믹학회지
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• 제33권5호
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• pp.519-523
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• 1996

시멘트 수화시 생성되는 수산화칼슘은 시멘트 모르타르의 강도 및 내구성을 감소시킨다. 이에 포졸란물질인 meta kaolin 및 silica fume을 이용하여 이러한 결점을 해결하고자 하였다. Meta kailin 및 silica fume의 함량변화에 대한 수산화칼슘의 감소는 Fourier의 시차열분석에 의해 규명되었고, mela kaolin 및 silica fume을 무첨가(0%)에 비하여 10% 이상 첨가시 수산화칼슘양이 큰 폭으로 감소함을 나타내었다. 이는 meta kaolin 및 silica fume의 SiO2 성분과 시멘트의 CaO와의 포졸란반응에 의한 것으로 나타났다.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.567.2-567
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• 2001

The purpose of this study was to evaluate the shape, the composition of Calcium Hydroxide Points (CH Point) and to determine the pH level in water. The shape of CH Point was measured by using a profile projector. The composition of the CH Point was analyzed by the X-ray diffraction and the EPMA. ＃60 CH Point was stored in 10ml of demineralized water that was replaced every day or not replaced for 7 days period. The pH levels of the water were measured by using an ion electrode with an ion meter every day.(omitted)

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.147-148
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• 2016

Generally, the vegetable oil contains glycerin esther and free fatty acid. When the vegetable oil reacts with concrete, the glycerin esther from oil induces saponification by reacting with and hydrolyzing calcium hydroxide from cement hydration. As a result of this saponification, it has been reported the expansion of concrete. although the free fatty acid from vegetable oil, as an acid, can decompose the concrete by producing soluble salt from calcium hydroxide or CSH, the hydration products of cement, there was no report on the harmful oil type for concrete. therefore, in this research, the property change of cement mortar incorporating fly ash was analyzed experimentally by immerging various types of vegetable oils.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.13-14
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• 2014

Ultra high performance concrete (UHPC) consists of cement, silica fume (SF), sand, fibers, water and superplasticizer. Typical water/binder-ratios are 0.15-0.20 with 20-30% of silica fume. The development off properties of hardening UHPC relates with both hydration of cement and pozzolanic reaction of silicafume. In this paper, by considering the production of calcium hydroxide in cement hydration and its consumption in the pozzolanic reaction, a numerical model is proposed to simulate the hydration of UHPC. The degree of hydration of cement and degree of reaction of silica fume are obtained as accompanied results from the proposed hydration model. The properties of hardening UHPC, such as degree of hydration of cement, calcium hydroxide contents, and compressive strength, are predicted from the contribution of cement hydration and pozzolanic reaction. The proposed model is verified through experimental data on concrete with different water-to-binder ratios and silica fume substitution ratios.