• Journal of the Korean Society for Heat Treatment
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• v.14 no.2
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• pp.96-102
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• 2001

$Al_2O_3$-copper alloy has been successfully made by gas atomization, mechanical alloying and hot pressing. In order to investigate microstructure and phase, it has been studied by using scanning electron microscope, transmission electron microscope and X-ray diffractometor. Mechanical properties have been examined using hardness tester and compressive tester according to annealing temperature. Although comparatively large Cu-Al powders are milled, the reaction between Cu-Al and $Cu_2O$ occurs and very fine $Al_2O_3$ particles in the matrix particles (5-10nm) are obtained. Compressive strength of this alloy is more than that of GlidCop Al60.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.127-130
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• 2002

Recently, the contamination with heavy metals in closed mines has been seriously considered since it can disturb human health through the polluted drinking-water and crops. Therefore, the concerns about the remediation of polluted land and treatment technology for hazardous matters have been accelerated. However, any of practical methods for treatment and/or remediation have not been yet suggested. In this research, a novel technology was studied to immobilize arsenic in tailings and soils disturbed by mining. In this technology, Fenton-like reaction were applied to immobilize arsenic in tailings. In the examination of Fenton-like reaction using pure pyrite, $H_2O$$_2$ and arsenic, the concentrations of extracted arsenic and iron were reduced up to 90 and 75%, respectively From the result of SEM-EDS, the Immobilization of arsenic was observed on the surface of pyrite. Thus, it can be said that the coating and/or adsorption prevents the extraction of arsenic.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.318-322
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• 2004

Arsenic is a toxic and carcinogenic metalloid, whose sources in nature include mineral dissolution and volcanic eruption. Abandoned mines and hazardous waste disposal sites are another major source of arsenic contamination of soil and aquatic systems. To predict concentrations of the toxic inorganic arsenic in aqueous phase. the biogeochemical redox processes and transport behavior need to be studied together and be coupled in a reactive transport model. A new reaction module describing the fate and transport of inorganic arsenic species (As(II)), dissolved oxygen, nitrate, ferrous iron, sulfate, and dissolved organic carbon are developed and incorporated into the RT3D code.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.492-494
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• 2004

The purpose of this study is to investigate the hydrochemical characteristics of groundwater in the Umsung area, and to elucidate the effect of host rock type, well depth and mineralization zone on the groundwater chemistry, We carried out chemical analysis, isotopic analysis, statistical analysis of Box-Whisker and trigging analysis for this study. The chemical and isotopic compositions of the groundwater is distinguished into two areas according to host rocks(Cretaceous sedimentary rocks and Jurassic granite) and recharge altitude, and is not greatly influenced by mineralization zone of the mines.

• Korean Journal of Microbiology
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• v.11 no.4
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• pp.189-195
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• 1973

With the gradual expansion of copper demands, the utilization of enormous tonnages of waste copper mineral containig up to 0.5% copper becomes available. In order to investigate the possibilities on the application of bacterial leaching method to waste dumps or abandoned mines, the authors had carried out microbial leaching of copper minerals by F.ferrooxidans isolated from the Dalsung copper mine water. The results obtained were as follows : 1. The copper extraction rate from the Dalsung chalcopyrite has been a little accerelated by using flasks in place of percolators. 2. The percentage of copper extracted from the Dalsung chalcopyrite sample was 100% in 30 days in the presence of iron-oxidizing bacteria F.ferrooxidans while 9.27% in the absence of bacteria. 3. F.ferroxidans was capable of producing sufficient quantities of ferric sulfate and sulfuric acid from ferrous iron to bring about the dissolution of 100% of copper from the Dalsung chalcopyrite.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.7-12
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• 1998

The waste sludge is by-produced about 20-30% of total production and arised to the severe problems of this mine's surrounding environmnet. This study was invested the composition of component, particle of size of the waste sludge by Chemical Analysis, X, R, D, Particle Size Analyzer and the physical properties (air content, slump, strength, etc) of concrete when the waste sludge is added into concrete. so, It's recomended the proper content of the waste sludge to be added into concrete. and then, is verified to be applied at batch plant in field. Above the results, the recomeded content of the waste sludge is about 2-4% (about 4-8% in cement) in aggregates and when it's added the recomended content, they are detected to be more or less changed the physical properties of concrete, ( equally strength and durability, little less air con tent, little increased shinkage, etc). but the application of the recomended content don't arise the problem of the basic quality control of concrete and physical properties.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.99-107
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• 2010

This paper is a study about the relationships among topologies and intuitionistic fuzzy topology induced, respectively, by approximation operators and an intuitionistic fuzzy approximation operator associated with an approximation space (X, R), when the relation R on X is precisely reflexive and transitive. In particular, we consider an intuitionistic fuzzy approximation operator on an approximation space X (i.e., a set X with a reflexive and transitive relation on it), which turns out to be an intuitionistic fuzzy closure operator. This intuitionistic fuzzy closure operator gives rise to two saturated fuzzy topologies on X and it turns out that all the level topologies of one of the fuzzy topology coincide and equal to the topology analogously induced on X by a crisp approximation operator. These observations are then applied to intuitionistic fuzzy automata.

• Journal of Powder Materials
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• v.7 no.4
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• pp.197-204
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• 2000

Gas atomization mechanical alloying and hot pressing have successfully made high temperature Al-9.45Fe-4.45Cr alloy. The microstructure and mechanical properties of this alloy has been studied by using optical microscope, scanning electron microscope, transmission electron microscope, X-ray diffractometer and compressive tester. It contains high concentration of transition elements of Fe and Cr, which form thermally stable dispersoids in the aluminum matrix. Proper oxidation of powders during ball milling strengthens the bulk extrudates by providing the obstacle particles. The oxide particles are very chemically and thermally stable and prevent the coarsening of the intermediate compounds.

• Explosives and Blasting
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• v.30 no.1
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• pp.52-59
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• 2012

Fragmentation is one factor to affect productivity and economic efficiency of mine. Authors investigate the blasting pattern and improve it step by step while observing the fragmentation results. Final pattern was suggested and the fragmentation improved 24 % compared to traditional pattern, with 50 % is passing rate.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.186-191
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• 1998

This study was investigated the distributions of heavy metal concentration in a soil near abandoned mine in Chung thong Nam Do. The abandoned mines were Gubong gold mine and Sinsung coal mine. The results were as follows : 1) The concentration of As and Pb in Gubong mine were 309.2mg/kg and 1163.5mg/kg, that is exceeded the countermeasure criteria. Cadmium concentration was 14.70mg/kg, that is exceeded anxiety criteria. But all items in Sinsung coal mine was detected below criteria. 2) The heavy metals contamination of riverbed soil by gold mine showed higher than coal mine. 3) The heavy metals contamination in the vicinal paddy and dry field soil area was higher than other mine. Arsenic concentration was 29.29mg/kg, that is exceeded the anxiety criteria as 10.22mg/kg.