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You, Don-Sang;Park, Cheon-Young
- Journal of the Korean earth science society
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- v.35 no.6
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- pp.401-411
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- 2014
In order to enhance the Au Ag leach rate, a mechanochemical activation process and a mixed thiourea-thiocyanate solution has been applied to Au concentrate. To achieve mechanochemical activation, the Au concentrate was mechanically ground using a dry and a wet process. The results of a particle size distribution analysis and an XRD analysis, average particle size and crystallite size were much smaller in the dry-sample than in the concentrate sample. As well the size was smaller in the wet-sample than in the dry-sample. In SEM and XRD analysis, the amorphization effect was observed in the wet-sample due to mechanochemical activation. Au Ag leaching experiments were carried out with a thiourea solution, a thiocyanate solution and a mixed thiourea-thiocyanate solution. The Au Ag leach rate was much greater in the dry-ground-sample than in the concentrate sample, and the leach rate was greater in the wet-ground-sample than in the dry-sample. The Au Ag leach rate was much greater in the thiocyanate solution than in the thiourea solution, and the leaching rate was much greater in the mixed thiourea-thiocyanate solution than in the thiocyanate solution. Up to a 99% leach rate for Au Ag were only achieved in the wet-sample using the mixed thiourea-thiocyanate leaching solution.
https://doi.org/10.5467/JKESS.2014.35.6.401 인용 PDF KSCI

Kim, Eun-Suk;Cho, Byung-Eun
- Journal of Korean Home Economics Education Association
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- v.22 no.3
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- pp.77-94
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- 2010
The purpose of this study was to develop a practical problem-based lesson plan for the "Understanding Myself and My Family" unit and to examine the effects of the lesson plan. Learning objectives and contents were selected, and a practical problem-based lesson plan for five sessions was developed and implemented. With 150 students participating in the study, a pre-test and post-test comprised of a questionnaire were conducted to explore the effectiveness of the lesson plan on the students' sex role characteristics, awareness of gender-role equity in occupational, familial and societal settings and of participation in household chores. Results from the post-test revealed that the students displayed androgynous sex-role characteristics, a heightened awareness of gender-role equity and a higher degree of participation in household chores after the five sessions. Assessment of the class was found to be very positive. Consequently the study showed that the lesson proved to be helpful for the students.
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