• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.4
• /
• pp.363-366
• /
• 2007

[ $Zn_2SiO_4:Mn$ ] green phosphors doped with $NH_4Cl$ and Al for PDP were synthesized by solid state reaction method. The luminescence of 532 nm in $Zn_2SiO_4:Mn$ phosphors was associated with $^4T_1{\to}^6A_1$ transition. Photoluminescence intensity of $Zn_2SiO_4:Mn$ doped with $NH_4Cl$ 15 mol% increased about two times as compared with that of $NH_4Cl$ non-doped sample. The color of the emission of Al-doped $Zn_2SiO_4:Mn$ phosphors changed to yellowish green.

• Nuclear Engineering and Technology
• /
• v.56 no.6
• /
• pp.2258-2265
• /
• 2024

The present investigation aims to study the role of Pr₂O₃ on the structural, physical, and radiation shielding properties of a dense cadmium lead borate glass. The XRD was used to affirm the glassy amorphous structure of fabricated sample materials. Moreover, the FTIR was used to record the change in the FT-IR spectra due to the addition of Pr₂O₃ in the wavenumber interval between 400 and 4000 cm^-1. The features of glass surfaces and the elemental analyses for the synthesized Pr₂O₃-reinforced cadmium lead borate glasses were performed using a SEM, supported by an energy-dispersive spectrometer. The γ-ray protection capacity was evaluated using the Monte Carlo method in a wide energy interval ranging between 0.015 and 15 MeV. The linear attenuation coefficient (LAC) at 1 MeV was reduced by a factor of 10 % from 0.372 cm^-1 to 0.340 cm^-1. The decrease in the LAC values negatively affected the other shielding properties such as half-value thickness and the transmission factor. Although the linear attenuation coefficient is decreased slightly with the partial substitution of CdO by Pr₂O₃ compound, the fabricated glass samples still have a high shielding capacity compared to the traditional commercial glasses as well as previous similar reported glasses.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.7
• /
• pp.1598-1602
• /
• 2009

The particle size of Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode powder was controlled effectively by dispersion using lauric acid as a surfactant. The samples treated by lauric acid showed smaller particles of approximately half the original size compared to the particles of a pristine sample. A structural change due to the dispersion of Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ powder was not detected. The rate performance of the Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode was improved by dispersion using lauric acid, which was likely due to the decrease of the particle size. In particular, a sample dispersed pristine powder using lauric acid (L2) presented a greatly enhanced discharge capacity and capacity retention at a high C rate. The discharge capacity of a pristine sample was only 133 m$Ahg^{-1}$ (3C rate) and 96 m$Ahg^{-1}$ (12C rate) at the tenth cycle. In contrast, the L2 electrode delivered higher discharge capacities of 160 m$Ahg^{-1}$ (3C rate) and 129 m$Ahg^{-1}$ (12C rate) at the tenth cycle. The capacity retention at a rate of 12C/2C was also enhanced from ~ 45% (pristine sample) to 57% (L2) by treatment with lauric acid.

• Journal of Life Science
• /
• v.25 no.6
• /
• pp.673-679
• /
• 2015

The culture conditions needed to maximize the production of laccase from Pholiota highlandensis mycelia were investigated. Among the tested media for laccase production, Coriolus versicolor medium (CVM; 2% dextrose, 0.4% peptone, 0.6% yeast extract, 0.046% KH₂PO₄, 0.1% K₂HPO₄, 0.05% MgSO₄·7H₂O) showed the highest activity for the enzyme. Then, to optimize culture conditions for laccase activity, the influences of various carbon, nitrogen, phosphorus, and inorganic salt sources in CVM were investigated. The optimum culture medium was 2% fructose, 0.4% peptone with 0.6% yeast extract, 0.05% NaH₂PO₄, and 0.05% MgSO₄·7H₂O as carbon, nitrogen, phosphorus, and inorganic salt sources, respectively. Several aromatic compounds in the medium enhanced laccase activity to varying degrees. Guaiacol induced maximum laccase production, yielding 114.1 U/ml laccase activity after cultivation for 11 days at 25℃. The optimum pH and temperature for laccase production were 8.0 and 35℃, respectively. Native polyacrylamide-gel electrophoresis (PAGE) followed by laccase-activity staining with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the substrate was performed to identify the presence of laccase under the optimum conditions studied. Zymogram analysis of the supernatant culture showed an enzymatic band with a molecular mass of about 90 kDa.

• Journal of Conservation Science
• /
• v.37 no.6
• /
• pp.712-722
• /
• 2021

This study presents a method for conserving shamanistic spirits in Chiseonggwang Buddha. Scientific investigation has revealed that these spirits have been subject to degeneration as a result of severe exfoliation and pollution. The materials and preservation treatment techniques used in create these shamanistic spirits were identified through visual inspection and using appropriate scientific equipment. The different types of background paper, background material, and color pigments used in create the shamanistic spirits were analyzed using a colorimeter, stereoscopic microscope, and SEM-EDS techniques. The analysis revealed that the pulp paper was used as the background and synthetic fiber polyester as the background material. In addition, the study of the pigment revealed that the color components were all synthetic, except for red lead [Pb₃O₄] and oyster shell white [CaCO₃]. Moreover, it was confirmed that the green pigment, identified as emerald green [Cu(C₂H₃O₂)₂.3Cu(AsO₂)₂], was a major component of shamanistic spirits in the late 19^th century. The shamanistic spirits in Chiseonggwang Buddha were conserved by identifying raw materials and pigments through this detailed analysis.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.6
• /
• pp.927-933
• /
• 2022

We synthesized (C₁₀H₈N₂H)₂Cr₂O₇, The structure of the product was characterized with FT-IR(infrared) and elemental analysis. The oxidation of benzyl alcohol by (C₁₀H₈N₂H)₂Cr₂O₇ in organic solvents showed that the reactivity increased with the increase of the dielectric constant. The oxidation of alcohols was examined by (C₁₀H₈N₂H)₂Cr₂O₇ in DMF, acetone. As a resuit, (C₁₀H₈N₂H)₂Cr₂O₇ was found as efficicent oxidizing agent that converted benzyl alcohol, allyl alcohol, primary alcohol and secondary alcohols to the corresponding aldehydes or ketones(65%~95%). The selective oxidation of alcohols was also examined by (C₁₀H₈N₂H)₂Cr₂O₇ in DMF, acetone. (C₁₀H₈N₂H)₂Cr₂O₇ was selective oxidizing agent(15%~95%) of benzyl alcohol, allyl alcohol and primary alcohol in the presence of secondary ones. In the presence of DMF solvent with acidic catalyst such as H₂SO₄. (C₁₀H₈N₂H)₂Cr₂O₇ oxidized benzyl alcohol(H) and its derivatives. The Hammett reaction constant(ρ) was -0.69(308K). The observed experimental data were used to rationalize the hydride ion transfer in the rate determining step.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.7
• /
• pp.610-614
• /
• 2005

In this paper, simple AT-cut crystal resonator utilizing $Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}TiO_3$ relaxator ceramics as load capacitator were designed and their frequency-temperature characteristics were investigated. In order to modify temperature dependance of dielectric constant, $Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}TiO_3$ ceramics were manufactured with the variations in Sr substitution. At the composition with $6\;mol\%$ Sr substitution as load capacitator, frequency-temperature characteristics of AT-cut crystal resonators with the series load capacitance were similarly varied as those of cut orientation variation, and also compensated.

• Journal of the Semiconductor & Display Technology
• /
• v.21 no.2
• /
• pp.85-89
• /
• 2022

We reported on annealing effect on Ga₂O₃/Al₂O₃/SiC devices grown by radio frequency sputtering method. Post-deposition annealing at 900 ℃ was performed, which results in crystallization in the Ga₂O₃ films. The major peaks (-401) and (403) of Ga₂O₃ which was thermally treated at 900 ℃ appears in the x-ray diffraction (XRD) results. Auger electron spectroscopy (AES) shows that Ga and Al atoms seems to be diffused into the opposite direction Al₂O₃ and Ga₂O₃ after annealing. Transfer and output characteristics of back-gate transistor were analyzed where SiC substrate is used as gate material. On-state current and on/off ratio increased almost 10⁹ and 10⁶ times higher in the 900 ℃ annealed sample.

• Journal of Environmental Science International
• /
• v.11 no.6
• /
• pp.589-596
• /
• 2002

Photocatalytic degradation of chlorpyrifos and diazinon, which are extensively used as an organophosphorous pesticide in the agriculture field, has been investigated with UV-radiated TiO$_2$ in aqueous phase. Photodegradation rate was increased with increasing pH of the solution. The removal efficiencies of chlorpyrifos and diazinon were 100% after 200 min in pH 9. Photodegradation followed a pseudo-first-order reaction. The rate constants of chlorpyrifos and diazinon were 0.0160min$\^$-1/ and 0.0180min$\^$-1/, respectively. NO$_3$$\^$-/, PO$_4$$\^$3-/, SO$_4$$\^$2-/ and Cl$\^$-/ were found as end products on the photocatalytic degradation of chlorpyrifos and diazinon with TiO$_2$/UV.

• Journal of the Korean institute of surface engineering
• /
• v.48 no.6
• /
• pp.315-321
• /
• 2015

Rare-earth zirconates, such as $La_2Zr_2O_7$ and $Gd_2Zr_2O_7$, have been investigated as one of the candidates for replacing conventional yttria-stabilized zirconia (YSZ) for thermal barrier coating (TBC) applications at higher turbine inlet temperatures. In this study, double-ceramic-layer (DCL) TBCs of YSZ 1st layer and $La_2Zr_2O_7$ top coat layer are fabricated by suspension plasma spray with serial liquid feeders. Microstructures, hardness profiles, and thermal durability of DCL-TBCs are also characterized. Fabricated DCL-TBCs of YSZ/$La_2Zr_2O_7$ exhibit excellent properties, such as adhesion strength (>25 MPa) and electrical thermal fatigue (~1429 cycles), which are comparable with TBCs fabricated by atmospheric plasma spray.