• 한국재료학회지
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• 제27권5호
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• pp.237-241
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• 2017

As a basic study for the removal of oxygen in solid Nd metal by metal Ca vapour, by using the thermodynamic data such as ${\Delta}G-T$ diagrams and Nd-O and Nd-Ca equilibrium diagrams, the amount of residual oxygen in solid Nd metal formed based on deoxidation reaction by Ca vapour, instead of by direct contact of solid Nd metal and Ca solution, was determined. Deoxidation experiments were carried out for solid Nd metal in a temperature range of $890{\sim}970^{\circ}C$ for 1h to 4h and content of addition Ca of 0.6~1.8 g (5~15 wt% of solid Nd metal). As a result, it was found that as deoxidation temperature increased, dissolved oxygen decreased. Especially, it was observed that a small amount of Nd-Ca alloy liquid was formed on the surface of the solid Nd metal sample deoxidized at $970^{\circ}C$ for approximately 1 hour. Also, it was found that if the content of addition Ca was 1.8 g (15 wt% of solid Nd metal) the amount of produced Nd-Ca alloy increased slightly. However, for the Nd sample with which the deoxidation reaction was performed at $930^{\circ}C$ for 4h with content of addition of Ca of 1.5 g (13 wt% of Nd metal), the residual oxygen was found to decreased to 12.00 ppm.

• 한국결정학회지
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• 제12권4호
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• pp.216-221
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• 2001

채석장 및 서재 가공장에서 폐기되는 미립의 분말의 석분 슬러지를 활용하고자 수영양생법으로 인조 석판재를 제조하였다. 석분 슬러지의 주성분은 석영 및 알루이나로서 여기에소석회 및 규사를 첨가하여 증기압, 수열 반응시간, 소석회의 첨가량 등이 인조석판재의 강도 및 비중에 미치는 영향을 조사하여 수열양샡법을 적용한 인조석재 제조공정을 확립하고자 하였다. 석분 슬러지 70%, 소석회 20% 및 규사 10%에 수분 10% 비율로 혼합한 후 200kg/㎠의 압력으로 성형하여 증기압이 20kg/㎠인 조건으로 3시간 동안 반응시켜 제조한 인조석재는 압축강동 614kg/㎠흡수율 0.48%, 겉보기 비중 1.88인 물성을 나타내었다. 또한 각종 산화물계 안료의 첨가에 의하여 다양한 색상과 문양을 보유한 인조석재의 제조가 가능하였다.

• Membrane and Water Treatment
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• 제2권3호
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• pp.147-158
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• 2011

Membrane distillation process was used for desalination of hot (333 K) geothermal water, which was applied in the plant producing heating water. The investigated water contained 120 g salts/$dm^3$, mainly NaCl. The mineral composition was studied using an ion chromatography method. The obtained rejection of solutes was closed to 100%, but the small amounts of $NH_3$ also diffused through the membrane together with water vapour. However, the composition of obtained distillate allowed to use it as a makeup water in the heating water system. The geothermal water under study was concentrated from 120 to 286 g NaCl/$dm^3$. This increase in the solution concentration caused the permeate flux decline by a 10-20%. The geothermal water contained sulphates, which was subjected to two-fold concentration to achieve the concentration 2.4-2.6 g $SO{_4}{^{2-}}/dm^3$ and the sulphates then crystallized in the form of calcium sulphate. As a results, an intensive membranes scaling and the permeate flux decline was observed. The XRD analysis indicated that beside the gypsum also the NaCl crystallites were deposited on the membrane surfaces. The fresh geothermal water dissolved the mixed $CaSO_4$ and NaCl deposit from the membrane surface. This property can be utilized for self-cleaning of MD modules. Using a batch feeding of MD installation, the concentration of geothermal water was carried out over 800 h, without significant performance losses.