• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.629-636
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• 2014

For surface modification, bulk metallic glass coatings were fabricated using metallic glass powder and a mixture of a self-fluxing alloy or/and hard metal alloys with a heat-resisting property using a high velocity oxy-fuel coating thermal spraying process. Microstructural analyses and mechanical tests were carried out using X-ray diffraction, a scanning electron microscope, an atomic force microscope, a three-dimensional optical profiler, and nanoindenation. As a result, the monolithic metallic glass coating was found to consist of solid particle and lamellae regions that included many pores. Second phase-reinforced composite coatings with a self-fluxing alloy or/and hard metal alloy additives were employed with in-situ $Cr_2Ni_3$ precipitate or/and ex-situ WC particles in an amorphous matrix. The mechanical behaviors of the solid particles and lamella regions showed large hardness and elastic modulus differences. The mechanical properties of the particle regions in the metallic glass composite coatings were superior to those of the lamellae regions in the monolithic metallic glass coatings, but indicated similar trends in matrix region of all the coating layers.

• Transactions of Materials Processing
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• v.19 no.5
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• pp.311-319
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• 2010

Rare earth metal Ce has a relatively low melting point and high specific gravity. Because of its significantly high affinity to oxygen, nitrogen and sulfur, it is highly usable as a steel refining agent. However, because Ce compound has relatively high specific gravity, it is difficult to be separated from molten steel through floatation, and it degrades the purity of molten steel, or may clog the nozzle in continuous casting. Such problem may be solved by using an appropriate deoxidation agent together with Ce and settling molten steel sufficiently after refining. Thus a fundamental study in the formation behavior of non-metallic inclusion in Ce added Hyper Duplex STS melts was investigated. The addition amount of Ce, melt temperature were considered as experimental variables. A main non-metallic inclusion in mother alloy is 51(wt%MnO) - 27.6(wt%SiO$_2$)- 10.9(wt%$Cr_2O_3$). Non-metallic inclusion was dramatically decreased and the particle size was fined as the amount of Ce increased. Moreover (%MnO) and (%SiO$_2$) of non-metallic inclusion were decreased. But (%$Al_2O_3$)were relatively increased. The number of non-metallic inclusion were decreased and the large particle size were increased by increasing the temperature of molten steel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.831-836
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• 2015

This paper dealt with the PD (partial discharge) characteristics produced by metallic particles presented in a gas insulated switchgear. Four types of metallic particles such as a ball, a trapezoid, a rectangle, and a twist were fabricated and placed in a PD cell filled with $SF_6$ gas. PD pulses were detected through a $50{\Omega}$ non-inductive resistor. Calibration was carried out according to IEC 60270 and the sensitivity was calculated as 4 mV/pC. Apparent charge, pulse count, DIV (discharge inception voltage), DEV (discharge extinction voltage), and TRPD (time resolved partial discharge) were analyzed. Among the metallic particle types, the twist frequently occurred PD pulse at the lowest DIV, while the rectangle showed the highest. DEV of the twist was about 2 times lower than that for the rectangle. Kurtosis of ball clustered at high value, and skewness of other three metallic particles distributed at low value. TRPD showed different distribution by metallic particle types.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.262-263
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• 2006

The free sintering of metallic powders blended with non sintering inclusions is investigated by the Discrete Element Method (DEM). Each particle, whatever its nature (metallic or inclusion) is modeled as a sphere that interacts with its neighbors. We investigate the retarding effect of the inclusions on the sintering kinetics. Also, we present a simple coarsening model for the metallic particles, which allows large particles to grow at the expense of the smallest.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.420-423
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• 2002

In this paper the characteristics of surface flashover for high temperature superconducting transformer(HTS) was discussed. The transformer, will be developed in the shell type with double pancake coil, isn't developed yet in the world. We conducted experiment of surface flashover that could occur in the windings of the transformer. First, we distinguished the surface flashover with electrode alignment into two type, such as parallel and vertical, and then compared with each characteristics of surface flashover. And the surface flashover with metallic particle was tested, it was also affected by the particle position. .

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.8-13
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• 2012

The experiments have been performed to obtain zinc complex compound with smaller particle size, which is used as a charge control agent in manufacturing toner. Metallic salts and polyhydric alcohols have been studied to investigate their effects on the formation of different sizes of zinc complex-compound particle. Reactants such as zinc chloride and 3,5-di-tert-butyl salicylic acid have been used to form the complex compound. Polyethylene glycol (PEG-300), glycerin and ethylene glycol have been added into the zinc chloride solution beforehand to lower the reaction rate in the formation of zinc complex-compound. Zirconium (IV) oxychloride octahydrate has been mixed in the zinc chloride solution beforehand to restrain crystals from growing. When PEG-300 and zirconium (IV) oxychloride octahydrate are used to lower the reaction rate and to restrain the particle size from growing, the average particle size of zinc complex compound decreases from 5.28 to 1.84 ${\mu}m$, which is 34.9% of 5.28 ${\mu}m$.

• Composites Research
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• v.36 no.3
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• pp.199-204
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• 2023

A combination of a metallic mesh and an adhesive layer of metallic particle/epoxy composite was introduced as an intermediate layer to enhance the adhesion between cold-sprayed particles and fiber-reinforced composites (FRCs). Aluminum was considered for both the metallic particles in the adhesive and the metallic mesh. To predict the mechanical characteristics of the intermediate bond layer under a high strain rate, the properties of the adhesive layer needed to be calculated or measured. Therefore, in this study, the Al particle/epoxy adhesive was homogenized by using a rule of mixture. To verify the homogenization, the penetration depth, and the thickness decrease after the cold spray deposition from the undeformed surface, was monitored with FE analysis and compared with experimental observation. The comparison displayed that the penetration depth was comparable to the diameters of one cold spray particle, and thus the homogenization approach can be reasonable for the prediction of the stress level of particulate polymer composite interlayer under a high strain rate for cold spray processing.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.2
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• pp.135-144
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• 2019

Targeted alpha therapy (TAT) based on metallic radionuclides has attracted a lot of attention lately due to its impressive therapeutic efficacy displayed in couple of clinical studies for cancer. Representative metallic radionuclides emitting alpha-particle include 225Ac, 213Bi, and 227Th, and there have been variety of TAT formulations based on different targeting moiety and chelating agents. In this review, we introduce strategies to label metallic radioisotopes with biomolecules and look at some of recent preclinical and clinical results of TAT for cancer.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1355-1367
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• 2007

This study summarizes the relations among $PM_{2.5}$ concentration, water-soluble ions concentration, metallic element Components characteristics and SPSS in negative ion and metallic element of $PM_{2.5}$ particle in Miryang.(By the urban area, the industrial complex area and the suburban area according to the season) $PM_{2.5}$ concentration of total 72 samples collected from 3 sites turned out to range from 3.47 to 34.7 ${\mu}g/m^3$, and the average concentration was the suburban area-the kin nup(16.00 ${\mu}g/m^3$) > the urban area-the roof of the old Miryang university(10.32 ${\mu}g/m^3$) > the industrial complex-Sapo industrial complex(10.29 ${\mu}g/m^3$). In particular, the suburban area had $PM_{2.5}$ concentration 1.5 times those of urban area, industrial complex. It was thought although the site was suburban and farm-side without pollutants around, it had a higher concentration value influenced by external factors including the brickyard, small-scale incinerator, driving range construction, construction on the Daegu-Busan express and the widening of the four-lane road between Miryang-Anyang nearby. As for water-soluble ions among $PM_{2.5}$ particle collected in Miryang area, $SO4_{2^-}$ accounted for 60% and $NO_{3^-}$, was 30% in spring and summer. And $NO_{3^-}$ accounted for 50% and $SO4_{2^-}$ was 35% in fall and winter. The AI value of metallic Components among $PM_{2.5}$ particle collected in Miryang area had a high value influenced by the apartment complex construction and the extension work of road. The industrial complex area had Zn concentration 3 times, and Fe concentration 2 times those of urban area and suburb area. When it comes to the relation with metallic elements in urban area, the highest coefficient of correlation was between Cr-Fe with 0.85, and Pb-Cd turned out in the reverse correlation. Among metallic elements, the coefficients of correlation between Zn and Cr, Mn, Fe, NI were high in industrial complex area. The highest coefficient of correlation was between Mn-Zn with 0.88, meanwhile Ni and Cu, Cd turned out in the reverse correlation in the suburb area. These coefficients of correlation are attributed to the difference in pollutant sources, rather than difference in pollutant and non-pollutant.

• Journal of the Korean institute of surface engineering
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• v.41 no.6
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• pp.301-307
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• 2008

In this paper, nanocrystallization of CuNiTiZr bulk metallic glass (BMG) subjecting to a kinetic spraying, dependent on impact velocity, was investigated by numerical and experimental approaches. The crystallization fraction and nucleation activation energy of initial feedstock and as-deposited coating were estimated by DSC and Kissinger method, respectively. The results of numerical modeling and experiment showed that the crystalline fraction and nucleation activation energy in BMG coatings were depended on kinetic energy of incident particle. Upon impact, the conversion of particle kinetic energy leads to not only decreasing free energy barrier but also increasing the driving force for an amorphous to crystalline phase transformation. The nanocrystallization of BMGs is associated with the strain energy delivered by a plastic deformation with a high strain rate.