• Resources Recycling
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• v.16 no.6
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• pp.34-38
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• 2007

For recycling of tantalum from obsolete condenser, physical separations and chlorination of tantalum scraps with $Cl_2$ and $CCl_4$ were investigated. The recovery ratio of tantalum from obsolete condenser was 98% by using a multidisciplinary process of crushing by stamp mill, wet gravity separation by the shaking table, and air classification. In the chlorination reaction of non-oxidized Ta anode with $Cl_2$, the highest weight loss ratio is at least 60%, while in the chlorination reaction of Ta anode with $CCl_4$, the reaction rate for the oxidized Ta anode is faster than that of the non-oxidized Ta anode.

• Resources Recycling
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• v.18 no.2
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• pp.30-38
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• 2009

In this research, we studied the scale-up triboelectrostatic process for separation of PVC from higher gravity fraction of plastic wastes produced from wet gravity separation process. High density polyethylene (HDPE) was found to be the most effective materials for a tribo-charger in the separation of plastic tailings. In a commercial scale triboelelctrostatic separator unit, using the HDPE pipe-line charger, a grade of 99.1% with PET, PS and others and a recovery of 86% was obtained under optimum conditions at over 250 kV/m electric field, a splitter position of -8 cm from the center, and less than 40% relative humidity. The developed unit can process the plastic wastes at a 300 kg/h, and the product can be utilized as RPF or RDF of over grade 2.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.289-302
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• 2007

Separation process of heavy minerals was performed with sand from Dunjang beach of Jaeundo, Shinangun, Chonnam, and the feasibility study separating heavy minerals was carried out, and their properties were studied. Samples were selected in three parts, which were upper part, middle part and lower part, with depth. Samples of heavy mineral groups separated with the spiral separator were chosen as starting materials, and they were separated with 3 times of table separation. Heavy minerals presenting in this area were ilmenite, zircon, rutile, anatase, monazite, and xenotime. In the results of 3 times of table separation, minor content of quartz, orthoclase, albite and muscovite were existed as gangue minerals. Accordingly, we concluded that additional specific gravity separation was needed. In the results of separation of heavy minerals by hand picking, it was confirmed that heavy minerals had various genesis because of their various roundness and color.

• Journal of the Mineralogical Society of Korea
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• v.22 no.3
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• pp.191-197
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• 2009

It is very important to raise the purity of silica for manufacturing metallurgical-grade silicon because the purification of silicon in the smelting process is very difficult. In present study, the silica sand which is obtained from Vietnam was mineralogically analyzed. Based on the results, a novel process to separate impurities from the silica sand was developed, which consisted of classification, specific gravity and magnetic separation steps. Using the developed process, high-grade silica sand concentrate containing over 99.8 wt% $SiO_2$ was prepared, being suitable for manufacturing the metallurgical-grade silicon.

• Korea journal of population studies
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• v.31 no.3
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• pp.159-178
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• 2008

The main purpose of this paper is to examine selectivity and rasons for move of internal migrants in Korea. There have only been a few studies available on the issues of selectivity and reasons for move of internal migration in Korea, mainly due to the lack of appropriate data. The main source of data for this analysis come from the raw data set of the 1997 Special Migration Survey conducted by the National Statistical Office. Analysis of selectivity of those who moved across the provincial boundary revealed that females, young adults, singles in their marital status and more educated are more likely to move. Among various reasons for move, employment related reason is the most important for all migration streams. But with different migration streams, diverse patterns are emerged. For those who moved into the Capital Region, employment related reason is outstanding. But those who moved out from the Capital Region, moved for employment as well as family related reasons. For movement within the Capital Region, housing related reason is equally important together with employment and family reason. The analysis also found that among individual attributes, age and marital status affect most significantly to the reasons for move. Education level and housing ownership are also important for explaining for variations in reasons for move.

• Resources Recycling
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• v.16 no.5
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• pp.13-18
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• 2007

The recycled aggregates produced from waste concrete by crushing and granularity adjusting processes only can't be used for structural aggregates because they display low density and high abrasion rate by including lots of mortar and cement paste. However, the recycled aggregates include a lot of aggregates for concrete. Using the heavy medium separation method that is one of the specific gravity separation methods, about 45% of the waste concrete could be converted to the recycled aggregates.

• Resources Recycling
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• v.29 no.5
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• pp.15-27
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• 2020

Microplastics are recognized as critical and serious environmental problem in worldwide. Plastics are inexpensive, lightweight, excellent in processability, and various in material-specific properties. Along industrial development, the production and disposal amount of plastics are also rapidly increasing. In particular, abundant plastic wastes are eventually disposed into marine environment with harmful impacts on the ecosystem. Therefore, lots of relevant studies were recently progressed in various fields. However, many studies are being just conducted due to its difficulty in applying a general treatment method for those small particle sizes and their various characteristics. In the meantime, lots of researches are being conducted on applying methods using physical properties such as specific gravity, magnetic, and electrostatic separation, which are beneficiation processes of minerals. However, since it is still in the laboratory stage, the development of larger scale separation technology for efficient treatment is urgent.

• Resources Recycling
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• v.25 no.1
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• pp.24-30
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• 2016

The study to obtain tantalum concentration from electronic components (ECs) on Printed circuit board assembly (PCBA) of laptop was conducted. Electronic components on laptop PCBA were detached from boards by using self-developed experimental apparatus. The detached electronic components were sieved and 93.2 wt.% of tantalum capacitors were concentrated from the size interval from 2.80 mm to 6.35 mm. The tantalum capacitors were pulverized by hammer mill and electrodes (anode and cathode) were removed from the grinding products by using magnetic separators under the magnetic force of 300 Gauss. Finally, tantalum concentrate was concentrated from the magnetic separator products by using Knelson concentrator, and the maximum efficiency of 76.9% was achieved under the operating condition of bowl rotating speed of 200 rpm, and fluidizing water flowrate of 7 L/min. The grade and recovery of Ta concentrate under the condition were 81.1% and 78.8%, respectively.

• The Microorganisms and Industry
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• v.13 no.3
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• pp.18-21
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• 1987

효소산업에 있어서 가장 큰 비중을 차지하는 것은 우량균주의 확보로서 이는 무한한 자원에서 보다 좋은 균주를 선별해야 하고 또 이를 계속 개량해야 한다. 즉, 경쟁대상보다 항상 우수한 균주를 확보하고 있어야 하는 것이다. 그 밖에도 여러 무제들이 산재해 있지만 여기서는 국내 공업적 효소 생산및 이용현황을 중심으로 하여 기술코자 한다.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.24 no.2
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• pp.65-71
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• 2018

Paper packs, glass bottles, metal cans, and plastic materials are classified according to packaging material recycling groups that are Extended Producer Responsibility (EPR). In the case of waste paper pack, the compressed cartons are dissociated to separate polyethylene films and other foreign substance, and then these are washed, pulverized and dried to produce toilet paper. Glass bottle for recycling is provided to the bottle manufacturers after the process of collecting the waste glass bottle, removing the foreign substance, sorting by color, crushing, raw materializing process. Waste glass recycling technology of Korea is largely manual, except for removal of metal components and low specific gravity materials. Metal can is classified into iron and aluminum cans through an automatic sorting machine, compressed, and reproduced as iron and aluminum through a blast furnace. In the case of composite plastic material, the selected compressed product is crushed and then recycled through melt molding and refined products are produced through solid fuel manufacturing steps through emulsification and compression molding through pyrolysis. In the recycling process of paper packs, glass bottles, metal cans, and plastic materials, the influx of recycled materials and other substances interferes with the recycling process and increases the recycling cost and time. Therefore, the government needs to improve the legal system which is necessary to use materials and structure that are easy to recycle from the design stage of products or packaging materials.