• Journal of Environmental Impact Assessment
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• 제16권6호
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• pp.407-419
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• 2007

This study investigated the predicted and abserved outflow of groundwater which occurred during tunnel constructions. Among the 586 road construction projects from 1986 to 2006, 4 route 25 tunnel construction areas and 26 waste water treatment facilities under construction were studied. Most of the tunnel outflow prediction in EIA (Environmental Impact Assessment) process have been classified into the 17 types of units depending on the assessor's options, which have not conformed to the request of the residents and non government organizations. The investigation results showed that the outflow of underground water in tunnel construction areas averaged about $0.133m^3/km{\cdot}min$ with the maximum $0.386m^3/km{\cdot}min$, and that the outflow mostly occurred in the early stage of tunnel excavation and diminished gradually. The prediction of outflow of underground water in the EIA process showed excessive results compared to observed outflow, the even 51.7 times. Consequently for more realistic prediction, current EIA method for prediction of outflow of underground water in tunnel construction areas has to adopt numerical methods coupled with hydraulics and geologic informations from unit methods of present time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.44-44
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• 2010

Conventional water treatment facilities like precipitation process need large-scale equipment and wide space to purify the wastewater of paper factory. In case of massive waste water, high gradient magnetic separation (HGMS) parts are more effective to purify it rapidly and to occupy relatively small space, since large voids at filter with HGMS are adopted. Cryo-cooled Nb-Ti superconducting magnet with room temperature bore in diameter of 100 mm and 600 mm in height was used for magnetic separator. Magnetic filters were designed by the analysis of magnetic field distribution at superconducting magnets.

• Journal of Korean Society of Water and Wastewater
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• 제31권3호
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• pp.257-262
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• 2017

Several disposal processes for waste sludge from wastewater treatment plants such as landfill, ocean dump, incineration, reuse as fuels or fertilizers are practiced. However, ocean dumping is prohibited by international treat. New constructions of landfill sites or incineration facilities are limited by NIMBY and reuse processes are still suffering from low energy yield. Therefore, development of alternative processes for sludge disposal are currently needed. In this study, alternative technique for sludge solubilization using HVI (high voltage impulse) was suggested and verified experimentally. Sludge solubilization was carried out for 90 minutes using HVI discharge with peak voltage of 16 kV and pulse duration for 40 microsecond. About 3~9 % of MLSS and MLVSS concentration were reduced, but the soluble COD, TN, TP of the sludge increased to 372 %, 56 % and 102 % respectively. It indicates that the flocs and/or cells of the sludge were damaged by HVI. These resulted in flocs-disintegration and cells-lysis, which means the internal matters were bursted out of the flocs as well as the cells. Thus, electrical conductivity in bulk solution was increased. All of the results verified that the HVI could be used as an alternative technique for sludge solubilization processes.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.837-842
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• 2012

A pilot scale circulating fluidized boiler (CFB) for refuse derived fuel (RDF) is designed and constructed to demonstrate a performance of CFB technology for waste fuel utilization. The boiler has a design capacity of 6 MWth with $400^{\circ}C$ 38 ata steam generation performance. The maximum steam rate of the boiler was about 8 ton/h. The main component of the fuel was RDF (Refuse Derived Fuel) with high volatile contents and showed fast ignition and easy combustion. The pilot plant showed over 99.5% of combustion efficiency. Stable operation of RDF CFBC depended on the content of non combustion materials other than ash and fast removal of them. Emission level was under legal limit except that of HCl without external flue gas treatment facilities. Also about 60% of fuel chlorine was absorbed to fly ash particles. For HCl emission control flue gas treatment technology is required such as wet and dry scrubber in order to comply with Korean regulation.

• Journal of the Korea Organic Resources Recycling Association
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• 제18권4호
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• pp.64-68
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• 2010

Recently, MBT(Mechanical Biological Treatment) facilities were built up and operated to separate and recycle MSW(Municipal Solid Wastes)in South Korea. However, the size distribution of MSW is very rough, and it is causing operation problem because MSW would be crushed in undersize diameter by mechanical equipment before feeding each seperation process. Also, the organic material should be pre-seperated to reuse recycle material in MSW. In this research, the reactor of 1ton/batch using the super-heated steam was tested to present the separation efficiency and the size distribution of MSW by experimental factors.

• Journal of the Korea Organic Resources Recycling Association
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• 제24권3호
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• pp.35-43
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• 2016

COD properties of waste activated sludge (WAS) were investigated for various solubilization rate of mechanical pretreatment method in anaerobic digestion process. Inert COD was 37.0% of total COD in untreated WAS. Particulate biodegradable COD was converted to soluble biodegradables and particulate unbiodegradables as solubilization was processed. Particulate unbiodegradable portion of COD in WAS can be increased as particulate biodegradable portion is decreased in case of relatively long SRT of biological treatment. Thus, COD properties of WAS should be investigated in case of relatively low particulate biodegradable COD, because of possible low effect of solubilization. COD removal rate in anaerobic digester was enhanced as much as 2.1% and 15.1% for solubilization rate 5% and 35% due to pretreatment, respectively. COD removal rate was increased from 25% to 40%, and methane gas generation was increased from $607m^3/d$ to $907m^3/d$ as particulate COD of WAS was solubilized to 35% in pretreatment facilities.

• Animal Bioscience
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• 제36권10호
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• pp.1612-1618
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• 2023

Objective: In our previous study, we observed that the addition of waste cooking oil (WCO) reduced ammonia (NH₃) emissions during laboratory-scale composting of dairy cattle manure under low-aeration condition. Therefore, this study aimed to evaluate the effect of addition of WCO on NH₃ emissions reduction during pilot-scale composting of dairy cattle manure, which is close to the conditions of practical composting treatment. Methods: Composting tests were conducted using pilot-scale composting facilities (1.8 m³ of capacity). The composting mixtures were prepared from manure, sawdust, and WCO. Two treatments were set: without WCO (Control) and with WCO added to 3 wt% of manure (WCO3). Composting was conducted under continuous aeration at 40 L/min, corresponding to 22.2 L/(min·m³) of the mixture at the start of composting. The changes in temperatures, NH₃ concentrations in the exhaust gases, and contents of the composted mixtures were analyzed. Based on these analysis results, the effect of WCO addition on NH₃ emissions and nitrogen loss during composting was evaluated. Results: During composting, the temperature increase of the composting mixture became higher, and the decreases of weight and water content of the mixture became larger in WCO3 than in Control. In the decrease of weight, and the residual weight and water content of the mixture, significant differences (p<0.05) were detected between the two treatments at the end of composting. The NH₃ concentrations in the exhaust gases tended to be lower in WCO3 than in Control. Nitrogen loss was 21.5% lower in WCO3 than in Control. Conclusion: Reduction of NH₃ emissions by the addition of WCO under low aeration condition was observed in pilot-scale composting, as well as in laboratory-scale composting. This result suggests that this method is effective in reducing NH₃ emissions in practical-scale composting.

• Journal of Soil and Groundwater Environment
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• 제10권6호
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• pp.75-80
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• 2005

Several metalliferous including Guedo mine, Manjung mine and Joil mine located at the upper watershed of Namhan river, were abandoned or closed since 1988 due to the mining industry promotion policy and thus disposed an enormous amount of mining wastes without a proper treatment facilities, resulting in soil pollution. In this research, total and fractional concentrations of heavy metals in mining wastes were analyzed and accordingly the degree of soil pollutions in the abandoned mine area were quantitatively assessed employing the several pollution indices. The mining waste samples from Guedo mine, Manjung mine and Joil mine recently abandoned were collected for the evaluation of the potential of water pollution by mining activities. Index of geoaccumulation fractional composition and removal efficiency of some heavy metals by different concentration of HCl treatment were analyzed. Index of geoaccumulation of Cd, Pb, Zn, Cu, Ni and Cr are 6, $4\~6,\;0\~6,\;4\~5$, 2 and 0 respectively. The index of geoaccumulation of Cd, Pb, Zn and Cu reveals the mining wastes has high pollution potential in the area. According to sequential extraction of metals in the mine wastes organic fraction of Cu, reducible fraction of Pb, residual fraction of Ni and Zn were the most abundant fraction of heavy metals in mining wastes.

• Korean Journal of Environmental Agriculture
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• 제40권2호
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• pp.83-91
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• 2021

BACKGROUND: Cultivation area using agricultural plastic film facilities in Korea is rapidly increasing every year; however, it accelerates the salt accumulation in soils due to repeated cultivation and excessive use of chemical fertilizers. Coal ash contains various trace elements and has high potential to be used in agricultural purposes. This research was aimed to improve the quality of salts-accumulated soils and crop growth grown in the plastic film facilities using the soil amendment derived from coal ash and zero-valent iron powder. METHODS AND RESULTS: Soil amendment used in the study was manufactured using coal ash with iron powder and subjected to a typical upland soil for soil quality enhancement and two salts-accumulated soils for crop growth. After one month incubation of the salts-accumulated soils treated with the soil amendment, soil pH increased significantly and soil EC decreased by approximately 50%, compared to the control or the treatment without the soil amendment. Since the soil salts' concentration is proportional to EC, the subjected soil amendment can be proposed as an effective way to overcome soil salts accumulation in agricultural plastic film facilities. For crop growth, the length of roots and stems increased by approximately 10% and the dry weight also increased by a maximum of 75%, compared to the control. CONCLUSION: The soil amendment made from waste resources such as coal ash and zero-valent iron was found to not only be effective in improving salt-accumulated soils and crop yield but also be safe against harmful heavy metals.

• Transactions of the KSME C: Technology and Education
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• 제3권4호
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• pp.257-264
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• 2015

To maintain sustainability of nuclear energy as an important energy source, both safety problem and Spent Nuclear Fuels(SNFs) problem should be solved. In case of Gen-IV reactors such as fast reactor, SNFs can be used as fuels by using fast neutrons. It can be a suitable treatment method of high-level waste in near future. Liquid metals such as Sodium or Lead-Bismuth Eutectic (LBE) can be possibly used as a coolant to use fast neutrons. In this paper, it was described that natural circulation parameter studies, design analyses, material selections and a completion of facilities. To develop a natural circulation facility, thermal hydraulic analyses were performed. Installation technique of liquid metal natural circulation were secured.