• Journal of Powder Materials
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• v.26 no.4
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• pp.282-289
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• 2019

Ti has received considerable attention for aerospace, vehicle, and semiconductor industry applications because of its acid-resistant nature, low density, and high mechanical strength. A common precursor used for preparing Ti materials is $TiCl_4$. To prepare high-purity $TiCl_4$, a process based on the removal of $VOCl_3$ has been widely applied. However, $VOCl_3$ removal by distillation and condensation is difficult because of the similar physical properties of $TiCl_4$ and $VOCl_3$. To circumvent this problem, in this study, we have developed a process for $VOCl_3$ removal using Cu powder and mineral oil as purifying agents. The effects of reaction time and temperature, and ratio of purifying agents on the $VOCl_3$ removal efficiency are investigated by chemical and structural measurements. Clear $TiCl_4$ is obtained after the removal of $VOCl_3$. Notably, complete removal of $VOCl_3$ is achieved with 2.0 wt% of mineral oil. Moreover, the refined $TiCl_4$ is used as a precursor for the synthesis of Ti powder. Ti powder is fabricated by a thermal reduction process at $1,100^{\circ}C$ using an $H_2-Ar$ gas mixture. The average size of the Ti powder particles is in the range of $1-3{\mu}m$.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.666-679
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• 1998

This study aims at providing the fundamental data on the field of cosmetics by comparing heavy metal concentration in terms of domestic/foreign products, items, companies and colors. This study has determined the concentration of chromium, lead, mangagnese, nickel, copper and vanadium in cosmetics such as moisturizer, concealer, foundation (Ivory-yellow), compact powder (Ivory-yellow), lip colo. (Red, brown), eye shadow (Red, brwon and dark green) and eye liner (Black) manufactured by five domestic cosmetic companies and five foreign cosmetic companies on the market. The samples have been collected in cosmetic stores in Pusan from Dec. lst 1996 to Jan. 3lst 1997. The results are as follows : 1. The heavy metal concentration in cosmetics was $2.420{\mu}g/g$ for chromium, $0.82{\mu}g/g$ for lead, $4.49{\mu}g/g$ for manganese, $1.69{\mu}g/g$for nickel, $0.53{\mu}g/g$ for copper, and $51{\mu}g/g$ for vanadium, respectively. 2. Lead and vanadium concentration were significantly higher in domestic cosmetics than foreign cosmetics(p<0.05). 3. The mean(GM) concentrations of heavy metal were different significantly (p<0.01) when classified with cosmetic items. The highest means shown at eye shadow in $Cr(14.96{\mu}g/g),\;Cu(1.32{\mu}g/g),\;V(1.28{\mu}g/g),\;and\;Ni(8.30{\mu}g/g)$, compact powder in $Pb(2.50{\mu}g/g)$, eye liner in $Mn(90.62{\mu}g/g)$. 4. The mean(GM) concentrations of heavy metal were different significantly (p<0.01) among colored cosmetics. The highest mean concentration of Cr, Ni, Cu and V were dark green-colored cosmetics, that of Mn was black-colored cosmetics, and that of Pb was ivory yellow- colored cosmetics.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.1
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• pp.1-9
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• 2010

In this study, the selective catalytic reduction of $NO_x$ with ammonia was carried out in a filter bag support reactor. The experiments were performed by powder type $MnO_x$ and $V_2O_5$/$TiO_2$ catalyst at low temperature between 130 and $250^{\circ}C$. Also, the effect of $SO_2$ and $H_2O$ on the NO conversion was investigated under our test conditions. The powder type catalysts were analyzed by X-ray photoelectron spectrum (XPS), X-ray diffraction(XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). It was observed that NO removal efficiency of the powder type $V_2O_5$/$TiO_2$ catalyst was 85% at low temperature($200^{\circ}C$) under presence of oxygen and that of $MnO_x$ was 50% at the same condition. The powder type $V_2O_5$/$TiO_2$ catalyst, in conclusion, was found to be available for SCR reaction in a filter bag support system.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.647-653
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• 2020

Stainless steel is used commonly in nuclear applications for shielding radiation, so in this study, three different types of new stainless steel samples were designed and developed. New stainless steel compound ratios were determined by using Monte Carlo Simulation program Geant 4 code. In the sample production, iron (Fe), nickel (Ni), chromium (Cr), silicium (Si), sulphur (S), carbon (C), molybdenum (Mo), manganese (Mn), wolfram (W), rhenium (Re), titanium (Ti) and vanadium (V), powder materials were used with powder metallurgy method. Total macroscopic cross sections, mean free path and transmission number were calculated for the fast neutron radiation shielding by using (Geant 4) code. In addition to neutron shielding, the gamma absorption parameters such as mass attenuation coefficients (MACs) and half value layer (HVL) were calculated using Win-XCOM software. Sulfuric acid abrasion and compressive strength tests were carried out and all samples showed good resistance to acid wear and pressure force. The neutron equivalent dose was measured using an average 4.5 MeV energy fast neutron source. Results were compared to 316LN type stainless steel, which commonly used in shielding radiation. New stainless steel samples were found to absorb neutron better than 316LN stainless steel at both low and high temperatures.

• Journal of Electrochemical Science and Technology
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• v.5 no.4
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• pp.109-114
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• 2014

The $Li_3V_2(PO_4)_3$/graphene nano-particles composite was successfully synthesized by a facile sol-gel method. The addition of a graphene in $Li_3V_2(PO_4)_3(LVP)$(LVP) showed the high crystallinity and influenced the morphology of the $Li_3V_2(PO_4)_3$ particles observed in X-ray diffraction (XRD) and scanning electron microscopy (SEM). The LVP/graphene samples were well connected, resulting in fast charge transfer. The effect of the addition graphene nano-particles on electrochemical performance of the materials was investigated. Compared with the pristine LVP, the LVP/graphene composite delivered a higher discharge capacity of $122mAh\;g^{-1}$ at 0.1 C-rate, better rate capability and cyclability in the potential range of 3.0-4.3 V. The electrochemical impedance spectra (EIS) measurement showed the improved electronic conductivity for the LVP/graphene composite, which can ensure the high specific capacity and rate capability.

• Journal of Powder Materials
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• v.28 no.5
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• pp.417-422
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• 2021

In the present work, Inconel 718 alloy is additively manufactured on the Ti-6Al-4V alloy, and a functionally graded material is built between Inconel 718 and Ti-6Al-4V alloys. The vanadium interlayer is applied to prevent the formation of detrimental intermetallic compounds between Ti-6Al-4V and Inconel 718 by direct joining. The additive manufacturing of Inconel 718 alloy is performed by changing the laser power and scan speed. The microstructures of the joint interface are characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and micro X-ray diffraction. Additive manufacturing is successfully performed by changing the energy input. The micro Vickers hardness of the additive manufactured Inconel 718 dramatically increased owing to the presence of the Cr-oxide phase, which is formed by the difference in energy input.

• Journal of Powder Materials
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• v.29 no.1
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• pp.8-13
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• 2022

In this study, we have prepared a Ti-6Al-4V/V/17-4 PH composite structure via a direct energy deposition process, and analyzed the interfaces using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The joint interfaces comprise two zones, one being a mixed zone in which V and 17-4PH are partially mixed and another being a fusion zone in the 17-4PH region which consists of Fe+FeV. It is observed that the power of the laser used in the deposition process affects the thickness of the mixed zone. When a 210 W laser is used, the thickness of the mixed zone is wider than that obtained using a 150 W laser, and the interface resembles a serrated shape. Moreover, irrespective of the laser power used, the expected σ phase is found to be absent in the V/17-4 PH stainless steel joint; however, many VN precipitates are observed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.108-114
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• 1998

The mechanical characteristics of the high speed steel by powder metallurgy process(PM-HSS) has been reported to improve with several alloying constituents, such as high carbon, vanadium and cobalt. In this paper, sliding wear test has been conducted using a pin-on-disc machine for three PM-HSS which contains 0%, 5% and 12% cobalt respectively, in order to evaluate the effect of cobalt on wear properties of PM-HSS. The results of this study showed that the wear resistance of PM-HSS has been increased by the addition of cobalt on the range of experimental friction velocities. When compared with the effect of addition of cobalt, the wear resistance of PM-HSS with 5% cobalt has been found to be superior to that of PM-HSS with 12% cobalt.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.107-111
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• 2005

We have performed a study on the electrochemical characteristics and nuclear ($^7Li$) magnetic resonance of $V_2O_5$ xerogels that have been synthesized by the sol-gel reaction of $V_2O_5$ powder with hydrogen peroxide. NMR measurements revealed that chemical shift of $Li^+$ ions varied as lithium ions were inserted into $V_2O_5$ xerogel and that several different sites for $Li^+$ ions existed in the $V_2O_5$ xerogel structure. The electrochemical properties of the xerogel electrodes did not depend much upon the concentration of $V_2O_5$ and HCl that were used for the synthesis of $V_2O_5$ gels. The specific capacity of $V_2O_5$ xerogels were about 140 mAh/g, similar to that of the xerogels prepared by the ion exchange method.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.723-732
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• 2020

The spent RHDS (Residue HydroDeSulfurization) catalyst is deactivated mainly by deposition of various contaminants such as coke, sulfur and vanadium on the surface of catalyst. To eliminate those contaminants, the following remanufacturing process was conducted. The first, heavy oil on the surface of the spent RHDS catalyst was removed by kerosene and dehydrated. The second, the high temperature incineration was carried out to eliminate coke and sulfur components deposited on the surface of spent RHDS catalyst. The third, the excessive quantity of Vanadium deposited on the surface of catalyst was removed by leaching process as follows: ultrasonic agitation was carried out at 50℃, for 10 seconds with 0.5% and 1% oxalic acid solution. The purpose of this process is to find out regenerated RHDS catalyst can be used as SCR catalyst for NOx reduction by controlling the vanadium residual content of the regenerated RHDS catalyst through leaching process. The composition of regenerated RHDS catalyst was analyzed by XRF and the NOx reduction efficiency was also measured by continuous catalytic fixed bed reactor. As the result, regenerated catalyst, with 0.5% oxalic acid, ultrasonic agitation in 10 seconds, showed the most stable NOx reduction efficiency. Also, in comparison with commercial SCR catalyst, the NOx reduction performance of regenerated catalyst was similar to that of commercial SCR catalyst at the temperature 375℃ and higher whereas was lower than commercial SCR catalyst at the temperature range between 200~250℃. Therefore, it was confirmed that the regenerated catalyst as powder form wash coated on the surface of metal corrugated substrate can be used for commercial SCR catalyst.