• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.943-946
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• 1997

Electropolishing is the controlled electrochemical removal of surface metal, resultmg in a brilliant appearance andimproved properties. Sometimes described as "reverse plating," the process has a leveling effect, which produces smoothnessand increased reflectivity. Unlike conventional mechanical finishing systems, the electropolishing does not smear, bend,stress or fracture the crystalline metal surface to achieve smoothness. Instead, electropolishing removes metal from thesurface producing a unidirectional pattern that is stress-free, microscopically smooth and often highly reflective. In addition,improved corrosion resistance and passivity are achieved on many ferrous and some non-ferrous alloys. Pure aluminium doesnot electropolish well, if at all, but most other alloys of aluminum electropolish excellently.Therefore, the aim of this study is to determine the characteristics of electropolishing aluminium alloy in term of currentdensity, machining time, temperature, electrode gap and workpiece surface measurementkpiece surface measurement

• Resources Recycling
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• v.20 no.4
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• pp.23-35
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• 2011

In order to review the recycling status of urban mine resources in Taiwan, background and history of recycling industries, system of the recovery fund management committee(RFMC), copper recycling with non-ferrous metals, recycling of ELV(end of life vehicles) and recycling of EAF dust were surveyed. Taiwan is a leading country of the world in the metal consumption per capita. Therefore, a lot of waste metals were generated. In other words, urban mine resources are abundant in Taiwan and have some advantages in recycling. There are more than thou-sand recycling plants in Taiwan. Half of them are non-ferrous metal recyclers.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.106-114
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• 1995

Direct implantation of metallic ion species has been employed in surface processing of industrial components and tools with very encouraging improvements in recent years. In spite of high technicla effectiveness, this new surface processing technique has not been extensively accepted by industries mainly because of high cost(capital and operating) compared with other competitive surface processing techniques. High current and large implantation area with eliminating the mass analyzer and the beam-scanning unit make metal vapor vacuum are(MEVVA)source ion implantation versatile, simple and cheap to operate and well suited to commercial surface processing. In this paper, the recent development of MEVVA source ion implantation technique ar Beijing Normal University has been reviewed and the results of production trials of several industrial components and tools implanted by MEVVA source ion implantation have been presented and discussed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.4
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• pp.157-160
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• 2007

The van der Pauw technique is one of the popular methods for determining the conductivity of flat metal samples. Traceability of the national standard for the conductivity has been achieved by direct current measurement techniques in national measurement institutes of many countries. But recently, alternative current measurement techniques for determining the conductivity of flat metal samples is also interested. In this study, we measured the conductivity of non-ferrous and ferrous flat metals at alternative current using van der Pauw technique. As measurement results, the conductivities of the samples were decreased according to increasing the test frequency even though the decreasing ratio was different.

• Analytical Science and Technology
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• v.26 no.5
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• pp.333-339
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• 2013

This study was conducted to build up the inventories of Pb isotopic compositions of major Pb pollution sources in South Korea. Since non-ferrous metal smelters are one of major anthropogenic sources, two smelters for zinc, each one of smelter for lead and copper were selected for the study. The Pb concentrations and isotopic compositions of metal ores, wastewater, sludge, metal rod and produced sulfuric acid were analysed to understand the Pb isotopic patterns in environment. The isotopic ratio, $^{206}Pb/^{207}Pb$, of zinc ores from zinc smelter were in the range of 1.179~1.198 and the ratio of waste, flue gas and products samples were 1.105~1.147. This results implied that the isotopic patterns of output samples showed mixing patterns between two distinct metal ore soerces. In 2011, major importing countries of zinc ore were Australia, Peru and Mexico. Thus Pb isotopic patterns from zinc smelter is originated from the mixing patterns between less radiogenic Australian ores and more radiogenic South America's ores. Lead smelters also showed the same mixing patterns with those of zinc smelters. However copper smelter showed same Pb isotopic patterns with more radiogenic South America's ores.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.04a
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• pp.343-344
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• 2008

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.239-240
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• 2008

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.25-35
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• 2005

This study analyzed total concentrations and existing forms of heavy metals in soils of Ulsan using a sequential extraction method. Soil samples were collected from 6 categorized areas including green, residential, heavy traffic, petrochemical industrial complex(IC), mechanical and shipbuilding IC, and non-ferrous metal IC areas. which represent different emission characteristics. The highest total concentrations of heavy metals by a sequential extraction analysis were observed in the soils collected from the non-ferrous metal IC area, followed by the mechanical and shipbuilding IC and heavy traffic areas. Dominant(> 50%) existing forms of Cd, Cr and Ni were residual forms followed by Fe and Mn oxides in almost areas. Residual fractions in the non-ferrous metal IC areas were relatively lower than those in other areas. However, the fractions of organic and sulphides in the IC areas were higher. The dominant farms of Cu were much different with the investigated areas. In most areas, the dominant forms of Pb and Zn were Fe and Mn oxides, followed by residual fraction for Pb. The exchangeable and carbonate fractions represent mobility of metallic elements in soils. They are also significantly affected by the environmental renditions, such as pHs of soil and rainfall. In this study the exchangeable and carbonate fractions were lower than other fractions. Because the total concentrations of heavy metals in the soils of the non-ferrous metal IC area were extremely high, however, the mobile fractions of heavy metals in the IC area would be significant. Thus a large amount of heavy metals can be released into plants, water bodies, and soils. Therefore, urgent measures, such as source control for soil remediation of heavy metals, in the non-ferrous metal IC areas are essentially required. Analysis results obtained from the sequential extraction and the aqua regia extraction showed a high correlation, whose determination coefficients(R2) of heavy metals except Cd approximately ranged from 0.7 to 0.9.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.599-600
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• 2005

The measurement method of electrical conductivity of the metal use a generally DC technique. Traceability to national standards in many countries is achieved using DC measurement technique and recently it's interested in AC technique. As a results for AC technique, the properties of electrical conductivity of non-ferrous and ferrous metals is decreasing at low frequency level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1729-1734
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• 2009

About 40 million automotive vehicles all over the world and 0.55 million in Korea were retired from use annually. Every nation is desperate to decrease environmental pollution by ELVs(End of Life Vehicles) and try to tighten the regulations. Europe passed laws requiring OEMs to increase vehicles' recovery and reuse rate to 95% by 2015 from current 84%. The ferrous parts, 75% of total automobile weight, are almost recycled whereas the remaining 25% of the non-metal -predominantly plastics as well as form, glass and rubber- and the non-ferrous materials -copper, nickel and aluminium- end up in landfills. The recycling status of non-ferrous materials represented by copper and nickel is reviewed and how much the recycling rate will be improved is calculated.