• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.187.2-187.2
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• 2011

태양광산업의 value chain중 up-stream쪽인 고순도 실리콘산업은 셀, 모듈, 시스템 쪽에 비하여 영업 이익률이나 부가가치 측면에서 매우 높은 성장성을 현재 보여주고 있으며 최근 원자력산업의 안전성 문제가 대두됨으로 인하여 태양광수요가 전 세계적으로 증대되는 경향을 나타내어 태양광용 실리콘의 수요가 확대됨과 아울러 spot시장에서의 가격 또한 상승하고 있다. 이런 관점에서 잉곳 및 웨이퍼 가공 중에 발생하는 고순도 실리콘 폐기물의 재활용 이 다시 주목받고 있다. 태양전지 웨이퍼(wafer)용 소재는 6N급 이상의 결정질 실리콘 잉곳(ingot)이 주를 이루며, 고효율의 셀을 제조하기 위해서 단결정 실리콘 잉곳이 많이 사용된다. 실리콘 단결정을 육성하는 방법에는 Floating zone 법, Czochralski 법, Bridgeman 법, CVD 등 매우 다양하다. 이 중 Czochralski 법은 전체 생산량의 대부분을 차지하고 있는 방법으로, 용융액에서 결정을 인상하여 ingot을 제작하는 방법이다. 그러나 대량의 전기에너지를 소비하여 제작되는 고순도의 실리콘 단결정 잉곳은 후 가공공정에서 그 절반 이상이 분말(powder) 및 슬러지(sludge)로 폐기되므로, 자원의 재활용 및 환경오염 측면에서 주요과제가 되고 있다. Czochralski 법으로 제작된 ingot의 경우 그 표면이 매끄럽지 못하여, 웨이퍼 단위의 가공 시 형태가 진원이 될 수 있도록 표면을 미리 연마(grinding)하는데, 이때에도 미세 분말이 다량 발생하게 된다. 본 연구에서는 이러한 고순도 단결정 실리콘 ingot의 연마 가공공정에서 발생한 미세 분말을 용해하여 보았다. 진공 챔버(chamber) 내부에 유도가열 코일과 냉도가니로 구성된 장비를 통해 전자기유도가열을 이용하여 실리콘 분말 폐기물을 용해하고, 그 시편을 ICP-MS 및 비저항 측정을 통해 분말 의 특성을 조사하여 재활용 가능성을 검토해 보았다.

• Journal of Microbiology and Biotechnology
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• v.23 no.8
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• pp.1084-1091
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• 2013

In this paper, two statistical methods were applied to optimize medium components to improve the production of the milk-clotting enzyme by Bacillus amyloliquefaciens D4. First, wheat bran juice, skim milk powder, and $Na_2HPO_4$ were shown to have significant effects on D4 enzyme production using the Plackett-Burman experimental design. Subsequently, an optimal medium was obtained using the Box-Behnken method, which consisted of 3.31 g/l of skim milk powder, 5.0 g/l of sucrose, 0.1 g/l of $FeSO_4{\cdot}7H_2O$, 0.1 g/l of $MgSO_4{\cdot}7H_2O$, 0.1 g/l of $MnSO_4{\cdot}2H_2O$, 0.1 g/l of $ZnSO_4{\cdot}7H_2O$, 1.52 g/l of $Na_2HPO_4$, and 172.45 g/l of wheat bran juice. With this optimal medium, the milk-clotting enzyme production was remarkably enhanced. The milk-clotting enzyme activity reached 3,326.7 SU/ml after incubation of 48 h, which was 1.76-fold higher than that of the basic medium, showing that the Plackett-Burman design and Box-Behnken response surface method are effective to optimize medium components, and B. amyloliquefaciens D4 possessed a high rennet-producing capacity in the optimal medium.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.683-687
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• 2008

When suspended solids are removed by natural sedimentation, it is necessary to use mainly huge equipments and waste great cost. This is a problem that must be solved certainly as soon as possible. In this study, suspended solids of yellow soil water were rapidly removed by controlling pH and amounts of magnetic powder, organic and inorganic flocculants. In the case of the suspended solids of 0.3% yellow soil water, the most excellent turbidity was achieved at pH between 7 and 7.5.

• Resources Recycling
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• v.12 no.6
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• pp.47-56
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• 2003

PVC(polyvinyl chloride) powder were mixed with EAF(Electric Arc Furnace) dust and made as pellets. In order to recover the hydrochloride emitted from pyrolysis of PVC and the valuable metals in dust through making chlorides, pellets were roasted at $300 ^{\circ}C$ and investigated about the generation of chlorides. Two dust samples were collected at I steel making Co. and P Co. (called I dust and P dust respectively), which were mainly composed of zincite and franklinite. It was confirmed that about 50% of Zn in I dust and 48% of Zn in P dust compose zincite. The emission of HCl gas was completed in 15 min at 30$0^{\circ}C$ and the HCl mostly reacted with dust and made chlorides under 20% PVC mixed ratio. Because the reaction of HCl with zincite was faster than with franklinit, when generation and volatilization of ferric chloride is not allowed, the equivalent PVC powder mixed ratio in pellet depended on the amount of zincite in dust.

• Journal of Animal Environmental Science
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• v.19 no.2
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• pp.101-108
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• 2013

This study was to investigate the effect of addition levels of odor reducing contents on reducing the concentration of odorous compounds. Slurry treatments included three levels mixture of horseradish powder (HP), mushroom waste (MW) and probiotics powder (PP), and non-treatment control (n=4 each group). Levels of odorous compounds were measured from the liquid slurry incubated in room temperature ($20{\sim}25^{\circ}C$) for 2 wk in chamber whose structure is similar to slurry pit. Concentration of phenols and indoles was lower (p<0.05) in level 1, which was mixed HP 0.01%, MW 0.4% and PP 0.004% (98.69, 1.87 ppm) compared to control. Short chain fatty acid (SCFA) and branched chain fatty acid (BCFA) was lowest (p<0.05) level 1 (6,557, 1675 ppm). Taken together, lower level are effective in reducing odorous compounds in pig slurry.

• Journal of Powder Materials
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• v.23 no.4
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• pp.325-330
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• 2016

Owing to increasing demand of rare metals present in ICT products, it is necessary to promote the rare metal recycling industry from an environmental viewpoint and to prevent climate change. Despite the fact that information for toxic substances is partly indicated, a legal basis and an international standard indicating usage of rare metals is insufficient. In order to address this issue, a newly created study group of environment and climate change at the ITU (International Telecommunication Union) is doing research to develop methodologies for recycling rare metals from ICT products in an eco-friendly way. Under this group, the Republic of Korea has established two international standards related to rare metals present in ICT products. The first is 'Release of rare metal information for ICT products (ITU-T L.1100)' and the other is 'Quantitative and qualitative analysis methods for rare metals (ITU-T L.1101)'. A new proposal for recommending the provision of rare metal information through a label by manufacturers and consumer/recycling businesses has been approved recently and is supposed to be published later in 2016. Moreover, these recommendations are also being extended to IEC, ISO and other standardization organizations and a strategy to reinforce the ability for domestic standardization is being established in accordance with industrial requirements. This will promote efficient recycling of rare metals from ICT products and will help improve the domestic supply of rare metals.

• Journal of the Korean institute of surface engineering
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• v.40 no.3
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• pp.125-130
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• 2007

Many fundamental studies have been carried out regarding waste water and hazardous gas treatment technology using the photolysis effect of $TiO_2$. However, photolysis of both organic and organic-inorganic binders immobilizing $TiO_2$ makes permanent use impossible. In this study we manufactured a catalytic electrode by nickel-$TiO_2$ composite plating in order to immobilize $TiO_2$. The surface properties according to the current density changes of cathode and concentration changes of $TiO_2$ powder in nickel plating bath has been analysed with EDX, XRF, SEM, Raman spectrometer etc. The characterization of the catalytic electrode in decomposition of organic compound has been obtained by using UV-Visible spectrophotometer through analysing concentration changes of methyl orange solution containing the catalytic electrode vs. time with projecting UV-light in the solution. The study shows that a catalytic electrode of nickel-$TiO_2$ composite plating with high-efficiency in decompostion of organic compound has been formed under high concentration of $TiO_2$ powder and low current density of cathode.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.93-93
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• 2018

This study disclosed the aqueous fruits extract of Rubus coreanus as a sustainable agent for the synthesis of Rubus coreanus zinc oxide nanoparticle (Rc-ZnO Nps) using as a reducing and capping precursor for co-precipitation method. The development of Rc-ZnO was assured by white precipitated powder and analyzed by spectroscopic and analytical instruments. The UV-visible (UV-Vis) studies indicate the maximum absorbance at 357nm which confirmed the formation of ZnO Nps and the purity, functional group and monodispersity were assured by field emission transmission electron microscopy (FE-TEM), Fourier Transform Infrared (FTIR) Spectroscopy and dynamic light scattering (DLS). The X-ray powder diffraction (XRD) data revealed the Nps is 23.16 nm in size, crystalline in nature and possess hexagonal wurtzite structure. The Rc-ZnO Nps were subjected for catalytic studies. The Malachite Green dye was degraded by Rc- ZnO NPs in both dark and light (100 W tungsten) conditions and it degraded about 90% at 4 hours observation in both cases. The biodegradable, low cost Rc-ZnO NPs can be a better weapon for waste water treatment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.69-78
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• 2014

The paper recycling becomes more important technology in terms of the reduction of the municipal waste and of saving natural resource such as wood. However the more utilization of recycled fiber would result in the higher contaminants in the papermaking processes and in the deterioration of the paper quality. The oil marks in the paper products becomes one of the major defects of paper products originated from paper recycling. The coagulation of various stickies in recycled fiber stock led to the oil marks. In this work, we applied functional polymer additives such as the dispersing agents, the fixing agents and the hydrophobic talc powder for the control of those stickies in order to remove the oil marks. The addition of the talc powder showed the great reduction in the oil marks of the packaging paper products. The hydrophobic surface of the talc particles collected the individual sticky materials and prevented their aggregation in the recycled fiber stock, which resulted in the great reduction of the oil marks on the paper products.

• Resources Recycling
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• v.4 no.1
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• pp.4-11
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• 1995

The amounts of waste stone and stone powder sludge that occurred in the quarry and processing plant of s stone plates, have been increased with the development of stone industry. The manufactunng process of 따tificial s stone was studied to reduce the outlet of these wastes and utilIze them as raw materials for architecture, interior decoration and art work. In order to compare the properties of artiflcial stone with those of natural building-stone, the physi$\alpha$II properties of artificial stone such as specific gravity, absorption ratio, elastic wave velocity, compressive s strength, tensile strength, shore hardness, elasticity and Poission's ratio were measured. From the mesaured d data of physical properties, it was found that physical propertIes of artificial stone were controlled by homogeneous m mixing ratio of constituents, molding pressure, and amount of binder. Also, from the thermo-gravimetric analysis, it was found that artIfIcial stone manufactured had a good thermal stability up to $300^{\circ}C$. It was concluded that t the optimum conditions for manufacturing process of artificial stone were $200kg/\textrm{cm}^2$ of molding pressure, 12-15 w weight % of binder amounts.