• Environmental Engineering Research
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• v.9 no.5
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• pp.193-200
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• 2004

A study of the treatment of piggery wastes using a multilayered metal-activated carbon system followed by carbon bed filtration was carried out at bench scale. From the physicochemical properties obtained from samples treated with aqueous solutions containing metallic ions such as Ag$^+$, Cu$^{2+}$, Na$^{-}$, K$^+$ and Mn$^{2+}$, main inspections are subjected to isothem shape, pore distribution with micropore, SEM and EDX. Multilayered metal-activated carbons were contacted to waste water to inwestigate the simultaneous catalytic effect for the COD, BOD, T-N and T-P removal. From these removal performance was achieved. The high efficiency of the multilayered metal-activated carbon bed, satisfactory removal performance was achieved. The high efficiency of the multilayered metal-activated carbon bed was derermined by the properties of this material for trapping, catalytic effect and adsorption of organic solid particles.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1921-1923
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• 2000

This paper describes the particle-initiated breakdown characteristics of various spacers, which have a ribbed surface, in the presence of a metallic particle. The particles was attached on the surface of each spacer. The breakdown voltages were measured by changing the particle position on the spacer, the length and thickness of the rib. Also the electrical field analyses were performed. As a result, the breakdown voltage of the spacer with two ribs was highest, and it was varied by the length and the thickness of the rib. Especially, in case of the rib with round edge the breakdown voltage was higher than that with rectangular edge, which complied with the result through the field analysis.

• Journal of Korea Foundry Society
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• v.22 no.2
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• pp.82-88
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• 2002

Al-5.5Zn-2.5Mg-l.5Cu semi-solid slurry was prepared by cooling the liquid metal with a low superheat to a solid and liquid co-existing temperature. Relatively round solid particles could be obtained in the slurry through the simple process. The prepared slurry was deformed into the metallic mold by a press and the mechanical properties of obtained specimens were investigated. Mold filling ability of the alloy slurry was also investigated and compared with that of A356 alloy. Al-Zn-Mg-Cu alloy showed lower mold filling ability than A356 alloy probably because small amount of eutectic phase is present and the heat of fusion generated during solidification is smaller than that of A356 alloy.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.268.1-268.1
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• 2013

Immobilization of conducting nanoparticles on a nanogap comprising two electrodes spaced at a distance comparable to the particle size can be used as a simple and sensitive method of detecting the particles. In this work, we have examined the performance of the nanogap devices in the measurement of metallic nanoparticles, particularly gold nanoparticles (Au NPs). Detection of pM-level Au NPs in an aqueous suspension was quite straightforward irrespective of the existence of non-conducting materials. Speed of detection or the time necessary for the completion of the measurement, however, was strongly dependent upon the immobilization process. Active trapping process was found to be much more efficient and also effective in the detection of nanoparticles than its passive counterpart.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.155-160
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• 2018

The materials used for 3D printing are mainly plastic and metal. These materials are usually used in the powdered form. In order to improve the surface roughness of a manufactured product, these powders should consist of small uniform spherical particles. However, the powdered forms are sold at a considerably higher price than bulk or wired materials. When a wire-type material is used instead of a powder, we can supply a relatively large amount of the material at one time as well as reduce the cost. Moreover, the use of this form of the material will increase the process efficiency. This paper deals with the technology required to feed a wire material in front of the tool movement and discusses the examples used for the verification.

• Journal of Powder Materials
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• v.27 no.6
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• pp.449-457
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• 2020

Iron and copper are practically immiscible in the equilibrium state, even though their atomic radii are similar. As non-equilibrium solid solutions, the metastable Fe-Cu alloys can be synthesized using special methods, such as rapid quenching, vapor deposition, sputtering, ion-beam mixing, and mechanical alloying. The complexity of these methods (multiple steps, low productivity, high cost, and non-eco-friendliness) is a hinderance for their industrial applications. Electrical explosion of wire (EEW) is a well-known and effective method for the synthesis of metallic and alloy nanoparticles, and fabrication using the EEW is a simple and economic process. Therefore, it can be potentially employed to circumvent this problem. In this work, we propose the synthesis of Fe-Cu nanoparticles using EEW in a suitable solution. The powder shape, size distribution, and alloying state are analyzed and discussed according to the conditions of the EEW.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.177-178
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• 2006

The results of monotonic and cyclic uniaxial compression tests, in which the deviatoric component of the stress is predominant, carried out on green and recrystallized iron compacts with different levels of density are presented and discussed in order to analyse the macro and micro-mechanisms governing the mechanical behaviour of non-sintered PM materials. The plastic deformation of the particles, especially at the contact areas between neighbouring grains, produces an internal friction responsible for the main features observed in the behaviour of green metallic compacts. These results show important discrepancies with the plasticity models, Cam-Clay and Drucker-Prager Cap.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.657-662
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• 2005

In this study, the deposition of micrometer-scale metallic interconnects on LCD glass for the repair of open-circuit type defects is investigated. Although there had been a few studies Since 1980 s for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and $W(CO)_6$ was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 nm depending on laser power and scan speed while the width was controlled between $3\~50{\mu}$ using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below 1 $O\cdot{\mu}m$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• Analytical Science and Technology
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• v.16 no.2
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• pp.143-151
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• 2003

In the present study, we made measurements of PM-bound metal concentrations from seven different urbanized locations in Seoul for the period covering March 2001 through May 2002. The measurement data were analyzed to explore the possible influences of spatial factors on metal distribution characteristics. To check for the importance of such aspects on metal distribution characteristics, the measured data were compared between different metals and between different sites by several criteria including (1) coefficient of variation (CV) values; (2) temporal variability; and (3) the abundance of strongly correlated pairs. The overall results of our study indicate strong diversity in the distribution characteristics of different metals. It is found that some metals (like Fe, Mn, and Pb) tend to exhibit strong compatibility among different study sites. However, no such compatibility appears to exist for certain metals like Cu. To account for the importance of spatial factors, complex relationships between source/sink processes and geochemical characteristics of a given metallic component may have to be examined in a systematic manner.

• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.199-203
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• 2002

To investigate an effect of sintering atmosphere on microstructure and properties of metallic particle dispersed ceramic based composites, the powder mixtures of $Al_2O_3$/Fe-Ni, synthesized by chemical solution process, were hot-pressed under different atmospheres such as hydrogen or argon gas and different sintering temperature. Hot-pressed composite in a hydrogen atmosphere exhibited less reaction phase of $FeAl_2O_4$ and enhanced mechanical properties than that in an argon atmosphere. Furthermore, decreasing hot-pressing temperature produced a refinement of ceramic matrix and metallic dispersion particles as well as improvement of mechanical properties. The change of mechanical properties in the composites with different sintering conditions was explained by microstructural characteristics relating to reaction phase formation.