• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.712-718
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• 1989

PMN ceramics with excess MgO addition in the range of 0 to 70m/o were prepared, and their electrical properties, such as dielectric constant, tan$\delta$, diffuseness coefficient, remanent polarization, coercive field and electrical conductivity were measured. Dielectric constant and remanent polarization increased with up to 5m/o excess MgO and then decreased presumely due to the precipitation of second phase, etc. Electrical conductivity slightly increased with the addition of excess MgO.

• Economic and Environmental Geology
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• v.44 no.5
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• pp.359-372
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• 2011

TA26 seamount, which is located at south part of Tonga arc, occurs widely hydrothermal plume and is area that sampled hostrock, hydrothermal ore and hydrothermal alteration rock for this study. Hostrocks are basalt and basaltic andesite. Altered rocks by hydrothermal solution consists of plagioclase, pyroxene, pyrite, ilmenite, amorphous silica, barite, smectite, iron sulfates, Fe-Si sulfates and Fe silicates. Gains and losses of major, trace and rare earth elements during wallrock alteration suggest that $K_2O$(+0.04~+0.45 g), $SiO_2$(-6.52~+10.56 g), $H_2O$(-0.03~+6.04 g), $SO_4$(-0.46~+17.54 g), S(-0.46~+13.45 g), total S(-0.51~+16.93 g), Ba(-7.60~+185078.62 g), Sr(-36.18~+3033.08 g), Ag(+54.83 g), Au(+1467.49 g), As(-5.80~+1030.80 g), Cd(+249.78 g), Cu(-100.57~+1357.85 g), Pb(+4.91~+532.65 g), Sb(-0.32~+66.59 g), V(-113.58~+102.94 g) and Zn(-49.56~+14989.92 g) elements are enriched from hydrothermal solution. Therefore, gained(enriched) elements(($K_2O$, $H_2O$, $SO_4$, S, total S, Ba, Sr, Ag, Au, As, Cd, Cu, Pb, Sb, V, Zn) represent a potentially tools for exploration of sea-floor hydrothermal deposits from the Tonga arc.

• Resources Recycling
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• v.26 no.4
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• pp.95-100
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• 2017

In this study, $Fe_2O_3$ was added as a flux to decrease melting temperature and refine during melting of Cu powder from scraped surface of the waste PCB (printed circuit board). The effect of $Fe_2O_3$ ratio to Cu powder and temperature on the recovery of Cu and content of impurities were investigated. It was found that the recovery of Cu was increased with increasing addition ratio of $Fe_2O_3$ and reaction temperature. The contents of O, Si and Fe in Cu phase were also decreased with increasing addition ratio of $Fe_2O_3$ and temperature. The formation of fayalite ($2FeO{\cdot}SiO_2$) and iron oxides phases in the slag was confirmed by XRD analysis after reaction with $Fe_2O_3$. Therefore, it was considered that the decrease of melting temperature and viscosity of slag by formation of fayalite slag contributed remarkably to the Cu recovery.

• International journal of advanced smart convergence
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• v.8 no.4
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• pp.26-33
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• 2019

We conducted research to evaluate economically and engineering about the synthesis of Magnesium Oxide, MgO, nanoparticles using physicochemical methods. The method used was economic evaluation by calculating GPM, BEP, PBP, and CNPV. The other method used was engineering perspective. MgO nanoparticles were synthesized by reacting Mg(NO₃)₂ and NaOH with a mole ratio 1: 2. Mg(OH)₂ formed was heated and calcined to remove water content and to oxidation to form MgO. An economic evaluation by calculating GPM and CNPV for the production of MgO nanoparticles on an industrial scale shows that the payback period (PBP) occur in the third year and profits increase each year. Tax variations show that the higher of tax, the lower profits received. When there was an increase of selling prices, the profit was greater. The variable cost used is the price of raw material. When there was an increased in the variable cost price, the payback period was longer and the profits was reduced. The benefit of this research is knowing the industrial production of MgO nanoparticles is beneficial. The function of MgO nanoparticles is a material for the manufacture of ceramics and can be used as an antimicrobial in the water filtration process.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.148-155
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• 2015

Electrospun $LaCoO_3$ perovskite nanofibers were produced for the air electrode in Zn-air rechargeable batteries using electrospinning technique with sequential calcination. The final calcination temperature was varied from 500 to $800^{\circ}C$ in order to determine its effect on the physical and electrochemical properties of the prepared $LaCoO_3$ perovskite nanofibers. The surface area of the electrospun $LaCoO_3$ perovskite nanofibers were observed to decrease with increasing final calcination temperature. Electrospun $LaCoO_3$ perovskite nanofibers calcined with final calcination temperature of $700^{\circ}C$ had the best electrocatalytic activity among the prepared perovskite nanofibers.

• Composites Research
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• v.26 no.1
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• pp.60-65
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• 2013

A nanolaminate consisting of alternate layers of aluminium oxide ($Al_2O_3$) (5 nm) and zirconium oxide ($ZrO_2$) (20 nm) was deposited at an optimized oxygen partial pressure of $3{\times}10^{-2}$ mbar by pulsed laser deposition. The nanolaminate film was analysed using high temperature X-ray diffraction (HTXRD) to study phase transition and thermal expansion behaviour. The surface morphology was investigated using field emission scanning electron microscopy (FE-SEM). High temperature X-ray diffraction indicated the crystallization temperature of tetragonal zirconia in the $Al_2O_3/ZrO_2$ multilayer-film was 873 K. The mean linear thermal expansion coefficient of tetragonal $ZrO_2$ was $4.7{\times}10^{-6}\;K^{-1}$ along a axis, while it was $13.68{\times}10^{-6}\;K{-1}$ along c axis in the temperature range 873-1373 K. The alumina was in amorphous nature. The FESEM studies showed the formation of uniform crystallites of zirconia with dense surface.

• Textile Coloration and Finishing
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• v.26 no.3
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• pp.195-200
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• 2014

Poly(vinyl alcohol)(PVA)/pullulan/titanium dioxide($TiO_2$) composite nanofibers were produced at different $TiO_2$ concentrations(1 and 3 wt.%) using the electrospinning method. The parameters of electrospinning including polymer contents, voltage and tip-to-collector distance(TCD) were optimized for fabrication process. The study showed that the best condition to make PVA/pullulan nanofiber and effect of $TiO_2$ nanoparticles. The PVA/pullulan/$TiO_2$ nanofibers were characterized by scanning electron microscope(SEM), transmission electron microscope(TEM), Thermogravimetric analysis (TGA) and X-ray diffraction(XRD).

• Journal of Korea Trade
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• v.26 no.8
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• pp.58-76
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• 2022

Purpose - This study examined the Rules of Origin (RoO) as a factor affecting free trade agreements' (FTA) utilization and analyzed the causal relationship and the effects of these factors on the export performance of automobile parts companies. Design/methodology - We analyzed and verified the impact of FTA utilization and the export performance of automobile parts companies by dividing the characteristics of the RoO into complexity and uncertainty. Following which, various statistical analyses were conducted on the interrelationships among these variables. Findings - This research analyzed the effect of the RoO factors of complexity and uncertainty on the use of FTA and the export performance of automobile parts companies. We found that these characteristics of RoO were generally related to and affected the FTA use and export performance of these companies. Based on this, this study's investigation into the characteristics of the RoO would then help companies in better utilizing the FTA, as well as providing suggestions on how to effectively respond to the application of the FTA in the future. Originality/value - Companies that want to utilize FTAs in international trade must follow the RoO. In the Regional Trade Agreement (RTA), the country-of-origin is a key factor, with the RoO being an important requirement for the application of preferential tariffs. These regulations are a requirement for receiving FTA preferential treatment; however, they also cause difficulties to companies in using the FTA.

• Proceedings of the Korea Crystallographic Association Conference
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• 2007.11a
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• pp.26-26
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• 2007

• Geotechnical Engineering
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• v.26 no.2
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• pp.26-34
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• 2010