• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.136-144
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• 2013

In this study, in order to establish a plan that will enable safe use of renewable resources such as diverse industrial by-products and urban recycled materials, we conducted experiments that focused on flow, bleeding, compressive strength and environmental pollution evaluation to evaluate the material properties of low strength concrete using BFS and SS. In the case of low strength concrete using BFS and SS, blending of at least BFS 6000 within a 30% range regardless of the type of sand used was found to be the most effective approach for improving the workability by securing the minimum unit quantity of water, restraining the bleeding ratio and establishing compressive strength by taking account of the applicability at the work site. In particular, in view of the efficient use of SS, the optimal mixing condition was found to be the mixing of BFS 8000 with in the 30% range, not only for improving the workability restraining the bleeding ratio and establishing the compressive strength but also for application to the work site. Further, the results of tests on hazardous substance content and those of elution tests conducted on soil cement using SS indicated that all values satisfied the environmental standards without any harmful effects on the surrounding environment.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.696-701
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• 2012

Non-aqueous processes have been developed for stable management and reuse of spent fuels. Nowadays, a plan for the management of spent fuel is being sought focusing on a non-aqueous process in Korea. Named as pyroprocessing, it includes an electrolytic reduction process using molten salt at high temperature for the spent fuels, which provides metallic product for a following electro-refining process. The electrolytic reduction process utilizes electrochemical reaction producing Li to convert oxides into metals in high temperature LiCl medium. Various kinds of elements in the spent fuels would be distributed in the system according to their respective reactivity with the reductant, Li, and the medium, LiCl. This study elucidates the reactions of the elements to understand the behavior of composite elements on the spent fuels by thermodynamic calculations. Uranium and transuranic are reduced into their metallic forms while rare-earth oxides, except for Eu, are stable against the reaction at a process temperature. This study also covers the tendency of reactions with respect to the temperature and, finally, estimates radioactivity and heat load on the distributed phases based on the reference spent fuel characteristics.

• Journal of Environmental Impact Assessment
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• v.22 no.2
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• pp.135-145
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• 2013

The recycling of coal bottom ash generated from coal power plants in Korea has been limited due to heterogenous characteristics of the materials. The most common management option for the ash is disposal in landfills (i.e. ash pond) near ocean. The presence of large coarse and fine materials in the ash has prompted the desire to beneficially use it in an application such as fill materials. Prior to reuse application as fill materials, the potential risks to the environment must be assessed with regard to the impacts. In this study, a total of nine test cells with bottom ash samples collected from pretreated bottom ash piles and coal ash pond in a coal-fired power plant were constructed and operated under the field conditions to evaluate the leachability over a period of 210 days. Leachate samples from the test cells were analyzed for a number of chemical parameters (e.g., pH, salinity, electrical conductance, anions, and metals). The concentrations of chemicals detected in the leachate were compared to appropriate standards (drinking water standard) with dilution attenuation factor, if possible, to assess potential leaching risks to the surrounding area. Based on the leachate analysis, most of the samples showed slightly high pH values for the coal ash contained test cells, and contained several ions such as sodium, potassium, calcium, magnesium, chloride, sulfate, and nitrate in relatively large quantities. Three elements (aluminum, boron, and barium) were commonly detected above their respective detection limits in a number of leachate samples, especially in the early leaching period of time. The results of the test cell study indicate that the pollutants in the leachate from the coal ash test cells were not of a major concern in terms of leaching risk to surface water and groundwater under field conditions as fill materials. However, care must be taken in extending these results to actual applications because the results presented in this study are based on the limited field test settings and time frame. Structural characteristics and analysis for coal bottom ash may be warranted to apply the materials to actual field conditions.

• Clean Technology
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• v.26 no.3
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• pp.228-236
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• 2020

Korea has an economy based on manufacturing industrial fields, which produce high amounts of hazardous wastes, in spite of few landfill candidates, and a significant concern for fine airborne particulates; therefore, traditional waste management is difficult to apply in this country. Moreover, waste collection and accumulation have recently been intensified by the waste import prohibitions or regulations in developing nations, the universalization of delivery services in Korea, and the global COVID-19 crisis. This study thus presents a domestic waste management strategy that aims to address the recent issues on waste. The contents of the strategy as the main results of the study include the (1) improvement of the compatibility of the classification codes between the domestic hazardous waste and the international ones such as those of the Basel Convention; (2) consideration of the mixed hazard indices to represent toxicity from low-content components such as rare earth metals often contained in electrical and electronic equipment waste; (3) management application based on risks throughout the life cycles of waste; (4) establishment of detailed material flow information of waste by integrating the Albaro system, Pollutant Release and Transfer Register (PRTR) system, and online trade databases; (5) real-time monitoring and prediction of the waste movement or discharge using positional sensors and geographic information systems, among others; and (6) selection and implementation of optimal treatment or recycling practices through Life Cycle Assessment (LCA) and clean technologies.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.3
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• pp.179-189
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• 2014

Pyroprocessing has been developed for the purpose of resolving the current spent nuclear fuel management issue and enhancing the recycle of valuable resources. An electrolytic reduction of the pyroprocessing is a process to reduce oxides into metals using LiCl as an electrolyte and requires a post-treatment process due to the inclusion of residual salt in porous metal products. A vacuum distillation has been adopted for various molten salt systems and could be applied to the post-treatment process of the electrolytic reduction. The residual salt in the metal products includes LiCl, alkali chlorides, and alkaline earth chlorides. In this paper, vapor pressures of chlorides have been estimated and the composition changes on the residual liquid during the vacuum distillation process have been calculated. A model combining a material balance and vapor-liquid equilibrium relations has been proposed under a constant vapor discharging flow rate and liquid composition changes have been calculated using the vapor pressures with respect to a dimensionless time. The behaviors have been compared with temperature and molten salt composition changes to simulate the process condition variation. The distillation of the residual salt has been dominated by LiCl which is the main component of the salt and CsCl of which vapor pressure is higher than that of LiCl would be readily removed. RbCl exhibits similar vapor pressure with LiCl and maintains its composition. However, $SrCl_2$ and $BaCl_2$ of which vapor pressures are much lower than that of LiCl are concentrated with time and expected to be possibly precipitated during the distillation when the initial compositions are increased.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.1
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• pp.100-114
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• 2005

Organic waste, which is defined as wastes derived from various biological organisms that contain more than 40% of organic materials, is generated about 100 million tons per year in Korea. These organic wastes are now controlled by several governmental entities, under different rules and regulations, leading to the improper management and inefficient treatment. Therefore, integrated management system is primarily needed for the efficient recycling of organic waste. In this study, six kinds of organic wastes, which are food waste, sludges(sewage, waste water, night soil), animal excreta, animals and plants residues, and three kinds of recycling by-products(compost, feed, anaerobic digestion by-products) made of organic wastes, were analyzed for their physical and chemical characteristics. On the basis of this result, a possibility for the efficient recycling of organic waste was investigated.

• Clean Technology
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• v.21 no.2
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• pp.85-89
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• 2015

Utilized in a variety of electronic components, electronic components industry with metallic ink technology was established itself as a major technology research and development was gradually increasing, silver ink that is excellent in conductivity and stability, have long been used in the industry of electronic components in recent years and silver ink has been the size of nanoscale particles dispersed by developing display, an electronic tag, a flexible circuit board or the like used in the semiconductor and electronics as has been highlighted in, however industry modernization of equipment by increasing the production and consumption of products generated during the production process and environmental pollutants by use of waste products is expected to bring a serious environmental problem. In this study, prepared by a wet reduction method, the manufacturing process of the silver nano-ink to the entire process of the environmental impact assessment (LCA) was evaluated using the techniques. Life cycle assessment software GaBi 6 was used as received from the relevant agencies of the silver nano-ink data with reference to the manufacturing process, building inventory was international organization for standardization (ISO) 14040, 14044 compliant LCA conducted over four stages.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.143-151
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• 2004

This study focused on examining the possibility of recycling mine solid waste as environmental materials, especially for porous media. Basic properties including mineralogical compositions, chemical compositions, and particle size distribution of the tailings from the Sangdong W mine were checked. The mineralogical and chemical compositions of the tailings samples were not much different in depth. According to Korean Standard Leaching Test for Wastes(KSLT), concentrations of heavy metals leached from the tailings were below the standard values. As a result of particle size analysis, the median diameter (d$_{50}$) of the tailings was in the range of 10 to 30 ${\mu}{\textrm}{m}$. The stable tailings slurry made up of 3 ${\mu}{\textrm}{m}$ in d$_{50}$ was prepared using Attrition Mill. The milling condition was 40 vol% in slurry concentration, 700 rpm in stirring speed, and 1 hour in milling time. PEI was added as dispersing agent. Concentrated slurry was extended to 3 times by foaming method. In the case of 3 times foamed slurry, the total and open porosity of ceramic supports sintered at 1,075$^{\circ}C$ for 90 minutes was about 80% and 72%, respectively. Pore size was in the range of 30∼350${\mu}{\textrm}{m}$. Therefore, the tailings could be recycled starting material for environmental materials such as macroporous ceramic support.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.905-909
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• 2002

This study was peformed to determine the anticarcinogenic activity of the Solanum tuberosum Peel (SP) on several microorganisms and human cancer cell lines. Among the various solvent fractions of SP, the ethylether Partition layer (SPMEE) showed the strongest antimicrobial activity, ethylacetate partition layer (SPMEA) and butanol partition layer (SPMB) resulted in good antimicrobial activity. We also determined the effect of SP extract and fractions on cytotoxicity, and chemopreventive effect on human cancer cells. The experiment was conducted to determine cytotoxicity of SP partition layers on HepG2, HeLa and MCF-7 cells by MTT assay. Among the various partition layers of SP, SPMEE and SPW were showed the strongest cytotoxic effects on all cancer cell lines. The quinone reductase induced activities of HepG2 cell, the butanol partition layer (SPMB) at a does of 40 $\mu\textrm{g}$/mL was 8.49 times more effective compared to the control value of 1.0. This value was significantly higher than that of previous results using the other materials. Therefore, based on these studies, SP may be developed into a potentially useful antimicrobial and anticarcinogenic agents.

• Journal of Energy Engineering
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• v.14 no.2 s.42
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• pp.159-166
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• 2005

In Korea, although the generation of waste plastic has been increasing, the rate of recycling is considerably low and moreover, there is no suitable method for the treatment of waste plastics. However, pyrolysis, which is appropriate for the treatment of highly polymerized compounds, such as plastics, has recently gained much interest. In this study, a property of the products from the pyrolysis of mixed waste plastics, with a possible practical use for the recycling oil produced, were assessed. First of all, in order to investigate the pyrolysis characteristic of waste plastics, TGA (Thermogravimetric analysis) and DCS (Differential Scanning Calorimetry) were performed on a number of different plastics, including PP, LDPE, HDPE, PET and PS, as well as others. According to the result, it appeared that PP was the most efficiently pyrolyzed by changing the temperature, followed by LDPE, HDPE, PET, PS and the other plastics, in that order. From the results, the optimum conditions f3r pyrolysis were set up, and the different waste plastics pyrolyzed. The recycling oil produced from the flammable gases generated during the pyrolysis was com-pared with fuel oil by an analysis using the petroleum quality inspection method on KS(Korea industrial Standard). The results of the analysis showed the recycling oil was of a similar standard to fuel oil, with the exception of the ignition point, with a quality somewhere between that of paraffin oil and diesel fuel. With respect to these results, the quality of the recycling oil produced by the pyrolysis of waste plastics was suf-ficient for use as fuel oil.