• Korean Journal of Mineralogy and Petrology
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• v.36 no.1
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• pp.19-32
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• 2023

This study was conducted to remove fluorine (F) (initial concentration of 9.5 mg/L) from leachate of reclaimed mine waste dump site via different methods: (1) co-precipitation using Ca-based materials; (2) adsorption using activated carbon and fly ash; and (3) coagulation and sedimentation using alum. The F removal efficiencies of each case were estimated as 65.6% (Ca co-precipitation), 27.9% (adsorption of activated carbon), 71.5% (adsorption of fly ash), and 96.6% (alum coagulation and sedimentation). In addition, the applicability of the continuous treatment process using alum coagulation was evaluated by lab-scale experiments using simulated mine drainage containing F of lower (6.4 mg/L) and higher (15.7 mg/L) concentrations, and it was confirmed that the treatment of both cases met the domestic standard (below 3 mg/L) for discharged water in clean areas. Furthermore, the results of bench-scale field tests indicated that the water quality standard of discharged water could be satisfied with the proper operation and management of the process.

• Korean Journal of Organic Agriculture
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• v.17 no.1
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• pp.55-62
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• 2009

In this paper, we assessed the growth of rice seedlings(Chucheong variety) in commercial organic growth medium that was substituted with different ratios of vermicast of oyster mushroom waste grown under potting alone, and potting and floor layering treatment. The commercial organic growth medium was substituted with vermicast at ratios of control, 2%, 4% and 6%, respectively. The control consisted of commercial organic growth medium alone without vermicast. Incorporation of $4%{\sim}6%$ vermicast of oyster mushroom waste into a commercial organic growth medium enhanced the growth of rice seedlings significantly as compared to commercial organic growth medium alone(control), and 2% amended with vermicast in potting treatment. This results demonstrate that substitution with low ratios of vermicast($4%{\sim}6%$) will promote growth of rice seedlings. The growth of rice seedlings in commercial organic growth medium alone without vermicast was enhanced significantly as compared to the substituted with vermicast in floor layering treatment, it may due to nutrient uptake by elongated root from the vermicast when applied to on the floor layering. Floor layering treatment is an effective method for potting processing of vermicast. The vermicast of oyster mushroom waste should have a high safety and great potential as materials of growth media for increasing plant growth, either as soil conditioner, or as substitution or amendments to commercial organic growth medium. For the enhanced growth of rice seedlings, demand to increase with total nitrogen, and decrease with the carbon and nitrogen ratio(C/N) of commercial organic growth medium supplied by such as vermicast.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.223-228
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• 2021

The final disposal method for asbestos building materials is to be landfilled at a designated waste landfill in accordance with the Waste Management Act. However, it is difficult to secure a domestic designated waste landfill site to landfill the entire amount of asbestos waste, which is expected to emit more than 400,000 ton/year by 2044. In this study, a detoxification treatment was performed on a ceiling tex with a density of 1.0 to 1.2g/cm³ containing 3 to 7% of chrysotile, and it was used as a reinforcing fiber for extruded panels. It was confirmed that asbestos components were detoxified through the reaction process using 30% oxalic acid and carbon dioxide, and it was recognized that these detoxifying properties were maintained even after extrusion molding. However, it was found that milling to a fiber size of less than 1mm for complete detoxification of asbestos resulted in a decrease in reinforcing performance. Therefore, in the case of using detoxified asbestos fibers in the extrusion molding process, it is considered desirable to add fibers with a length of 5mm or more to improve the reinforcing performance.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1315-1323
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• 2018

We studied the carbonization due to the annealing condition of waste coffee powder for application as an active anode material for lithium-ion batteries (LIBs). The coffee powder used as an active anode material for LIBs was obtained from coffee beans, not from a coffee shells. The waste coffee powder was dried in air and heat-treated in an $Ar/H_2$ atmosphere to obtain a pore-forming activated carbon powder. The specific capacity of the sample annealed at $700^{\circ}C$ was still 303 mAh/g after 1000 cycles at a current density of 1000 mA/g and with a coulombic efficiency of over 99.5%. The number of pores and the pore size of the waste coffee powder were increased due to chemical treatment with KOH, which had the some effect as an increased specific surface area. The waste coffee powder is considered to be a very promising active anode material because of both its excellent electrochemical properties due to enhanced carrier conduction and its being a cost effective resource for use in LIBs.

• Journal of Climate Change Research
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• v.3 no.2
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• pp.129-142
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• 2012

This study was carried out to evaluate carbon footprint during unhulled rice production and to compare mitigation technologies of methane, main carbon source during rice production, Carbon footprint of unhulled rice was a sum of $CO_2$ emission of agri-materials manufacture, rice cultivation and waste treatment. It was emitted 1.40 kg $CO_2$ during unhulled rice production, its distribution was 71.1% by $CH_4$ emission of rice cultivation, 11.8% of $N_2O$ emission by nitrogen application and 7.6% of complex fertilizer manufacture. $CH_4$ emission could be mitigated by some technologies; cultivation of the early maturing rice variety emitted lower by 44.4% than the mid maturing variety, intermittent drainage of submerged water by 43.8% than the continuous flooding condition, direct seeding by 32.0% than transplanting cultivation, no-ploughing by 20.9% than ploughing cultivation. It means that LCA on Global Warming Potential and the statistical data on innovated technical practice are key tools to systemize Measurable-Reportable-Verifiable (MRV) system for carbon footprint and carbon emission trade in the farm base.

• Computers and Concrete
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• v.19 no.4
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• pp.419-427
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• 2017

With the rising global environmental awareness on energy saving and carbon reduction, as well as the environmental transition and natural disasters resulted from the greenhouse effect, waste resources should be efficiently used to save environmental space and achieve environmental protection principle of "sustainable development and recycling". This study used recycled cement mortar and adopted the volumetric method for experimental design, which replaced cement (0%, 10%, 20%, 30%) with recycled materials (fly ash, slag, glass powder) to test compressive strength and ultrasonic pulse velocity (UPV). The hyperbolic function for nonlinear multivariate regression analysis was used to build prediction models, in order to study the effect of different recycled material addition levels (the function of $R_m$(F, S, G) was used and be a representative of the content of recycled materials, such as fly ash, slag and glass) on the compressive strength and UPV of cement mortar. The calculated results are in accordance with laboratory-measured data, which are the mortar compressive strength and UPV of various mix proportions. From the comparison between the prediction analysis values and test results, the coefficient of determination $R^2$ and MAPE (mean absolute percentage error) value of compressive strength are 0.970-0.988 and 5.57-8.84%, respectively. Furthermore, the $R^2$ and MAPE values for UPV are 0.960-0.987 and 1.52-1.74%, respectively. All of the $R^2$ and MAPE values are closely to 1.0 and less than 10%, respectively. Thus, the prediction models established in this study have excellent predictive ability of compressive strength and UPV for recycled materials applied in cement mortar.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.1
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• pp.31-40
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• 2005

High temperature - high pressure apparatus was developed to simulate nickel fewite corrosion products which were main compositions of the radioactive crud in the nuclear power plant. Corrosion product similar to the crud was obtained by a tube accumulator system. Nickel alloy (Inconel 690) and carbon steel (SA106 Gr. C) were corroded at 270 $\^{circ}C$ in the corrosion product generator. Ni ions and Fe ions dissolved by corrosion reaction were able to be transported to the accumulator because the crud generation mechanism was the solubility change with temperature. To evaluate the properties of simulated corrosion products, scanning electron microscope (SEM) observation and EDAX analysis were performed. SEM observation of corrosion product showed the needlelike or crystal structure of oxide depending on precipitating location. The crystal oxide was the nickel ferrite, which was similar to the crud in nuclear power plants.

• Textile Coloration and Finishing
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• v.35 no.3
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• pp.169-178
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• 2023

The extended use of polyester nowadays has increased the amount of waste polyester (PET) released into the environment. Although these materials don't directly harm living things or the ecosystem, their inability to biodegrade remains one of the major global threats, driving up the amount of solid waste made up of PET. Environmental concerns have approved an increasing interest in recycled PET however the production of recycled PET with sufficient mechanical properties is still a challenge. Recycled Polyester (rPET) yarns are inexpensive and have the potential to acquire better mechanical characteristics through physical treatments, particularly by using technically simple method like uniaxial drawing. This study inspected the drawn behavior of virgin PET yarns and rPET yarns under various drawing parameters by first analyzing the initial material characteristics of both yarn. The impact of stretching on mechanical and morphological properties was also investigated. The results showed that virgin PET has better properties than rPET yarn; however, mechanical properties resembling virgin PET are achieved after optimizing the draw ratio.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.5
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• pp.416-422
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• 2016

Lots of plastics are widely used in a variety of industrial field. And the amount of plastic waste is massively produced. In the study of waste recycling, it is emerged as an important issue to prevent the waste of potentially useful resource materials as well as to reduce ecological damage. So, the recycling of plastic waste has been currently paid attention to from the view point of reuse. Existing automatic sorting system consist of near infrared ray (NIR) sensors to classify the types of plastics. But the classification of black plastics still remains a challenge. Black plastics which contains carbon black are not almost classified by NIR because of the characteristic of the light absorption of black plastics. This study is focused on handling how to identify black plastics instead of NIR. Raman spectroscopy is used to get qualitative as well as quantitative analysis of black plastics. In order to improve the performance of identification, Support Vector Machine(SVM) classifier and Principal Component Analysis(PCA) are exploited to more preferably classify some kinds of the black plastics, and to analyze the characteristic of each data.

• Ocean and Polar Research
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• v.38 no.3
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• pp.225-234
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• 2016

This project sought to conduct an economic feasibility study regarding the commercial production of bio-hydrogen by the marine hyperthermophilic archaeon, Thermococcus onnurineus NA1 using carbon monoxide-containing industrial off-gas. We carried out the economic evaluation of the bio-hydrogen production process using the raw material of steel mill by-product gas. The process parameter was as follows: $H_2$ production rate was 5.6 L/L/h; the conversion of carbon monoxide was 60.7%. This project established an evaluation criterion for about 10,000 tonne/year. Inflation factors were considered as 3%. The operating costs were recalculated based on prices in 2014. The total investment required for development was covered 30% by capital and 70% by a loan. The operation cost for the 0.5-year test and integration, and the cost for the first three months in the 50% production period were considered as the working capital in the cost estimation. The costs required for the rental of office space, facilities, and other related costs from the construction through to full-scale production periods were considered as continuing expenses. Materials, energy, waste disposal and other charges were considered as the operating cost of the development system. Depreciation, tax, maintenance and repair, insurance, labor, interest rate charges, general and administrative costs, lubrication and miscellaneous expenses were also calculated. The hydrogen price was set at US$ 4.15/kg for the economic evaluation. As a result, the process was considered to be economical with the payback period of 6.3 years, NPV of 18 billion Won and IRR of 26.7%.