• Resources Recycling
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• v.15 no.2 s.70
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• pp.37-44
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• 2006

The total amount of graphite reserves in Korea is about 260 thousand tons. Graphite larks international competitiveness it is mined in only few mines, but recently the demand of portable electronic has increased. Therefore a research for manufacturing domestic high purity graphite is necessary because all of high purity graphite used electrode of 2nd batter depends on expensive importation. A preprocessing level for producing high purity graphite, flotation was conducted using microbubble column machine. In this research $D_{50}=10.314{\mu}m$ sample was used which was produced after grinding 29.50% F.C. primary crushing sample($D_{50}=69.393{\mu}m$) for 20 minutes through attrition mill. As a result using this sample, product above 95% F.C. with recovery over 90% was obtained with only after first stage process through the microbubble column.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2016.10a
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• pp.429-430
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• 2016

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.40-46
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• 2024

A novel approach is presented to address issues associated with the use of strong acidic solutions for the leaching of magnesium oxide (MgO) from spent magnesia-carbon refractories. An ultrasonic flotation and separation process is employed, with a mildly acidic solvent, acetic acid, used to selectively chelate MgO from the spent refractories. When using 2 M acetic acid as a solvent, the recovery of the graphite exhibited 99.7 % with high purity of 72.7 %, showing a significant improvement compared to using water as the solvent. Furthermore, the technology presented in this study offers a method for producing magnesium acetate through the reaction of MgO in spent refractory with acetic acid, providing a means for the purification and separation of graphite.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2015.10a
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• pp.279-280
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• 2015

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2016.05a
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• pp.315-316
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• 2016

• Journal of the Korean Ceramic Society
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• v.38 no.5
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• pp.485-491
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• 2001

일반 산업 및 원자력 관련 산업용 구조소재의 표면특성 향상을 위해 저압 화학기상 증착법에 의해 15~25cm 직경의 흑연기판 위에 고순도의 치밀한 SiC 증착층을 제조하였다. 미세구조와 두께가 균일한 증착층을 얻기 위하여 증착온도의 균일성, 반응가스 고갈효과, 가스 흐름 형태 등의 영향을 고려하였다. 이중에서 반응 용기내의 가스 흐름 형태가 증착층의 균일도에 가장 큰 영향을 주는 것으로 판단되었으며 가스 주입구의 위치와 크기를 조정함으로써 25cm의 직경을 갖는 흑연 기판에 두께 편차가 $\pm$12% 이내인 SiC 증착막을 제조할 수 있었다.

• Journal of Korea Foundry Society
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• v.11 no.3
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• pp.236-244
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• 1991

This paper describes a study of the nucleation and growth of graphite crystal of levitation melted high purity Fe-C-Si alloys with emphasis on hypereutectic composition. Spherulitic graphite was observed to form at high purity alloy and converted to compacted by changing the starting iron from ultra-pure zone refined iron to 99.95 pct electrolitic iron. Residual C-C clusters might be acting as an effective nucleation site for graphite, and sulphur was the element to prevent graphite from nucleating. The graphite morphology changed from compacted to spherulitic as the sulphur content decreased.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.7-16
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• 1991

Measurement of Co-60 gamma rays has been made for establishment of exposure standard and analyze it's overall uncertainties. Exposure rate determined by the charge mode method using vibrating reed amplifier with cylinderical type cavity chamber. The values of a variety of physical constants and the correction factors are evaluated. The resulting exposure rate is 690.81 R/h at the distance of 1m from the source and the related uncertainties is ${\pm}0.8%$

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.252-256
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• 1995

A study was carried out for the development of direct determination of antimony in high purity copper metal without preseparation. The large excess of copper seemed to be performed as the matrix modifier to enhance the absorbance of antimony in copper metal. Sensitivity enhancement of Sb was obtained at the condition of the ashing temperature of $600^{\circ}C(20s){\sim}700^{\circ}C(10s)$ rather than $1000^{\circ}C(20s){\sim}1100^{\circ}C(10s)$, and the atomization temperature of $2200^{\circ}C.$ The operating pressure of argon gas was readjusted to the optimum condition at 2.0 kg/$cm^2.$ The linearity of the Sb calibration graph could be obtained in the range of 20 ppb up to 200 ppb Sb in existence of 5,000 ppm Cu with the coefficient of variation of about 5%.

• Resources Recycling
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• v.26 no.3
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• pp.39-46
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• 2017

AlN powder was prepared by carbon reduction and subsequent nitridation method through lab- scale experiments. AlN powder was synthesized using the mixture of high purity $Al_2O_3$ powder and carbon black at $1,600{\sim}1,700^{\circ}C$ for 0.5~6 hours under nitrogen atmosphere (flow rate of nitrogen gas: $4.7{\times}10^{-6}{\sim}20{\times}10^{-6}m^3/sec$) with variation of charged height of the mixture powder. Experimental results showed that size of the synthesized particles grows with increasing of temperature. The reaction activation energy was calculated as 382 kJ/mol at the temperature range, and it was considered that chemical reaction is the rate determining step. Content of oxygen and nitrogen of the prpared samples were 0.71~0.96 wt% and 30.7~35.1 wt%. The results was similar with those of the commercial AlN product.