• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.6
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• pp.253-257
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• 2008

To enhance the luminescence properties, the red phosphor composed of $(Y,\;Zn)_2O_3$:$Eu^{3+}$ as doping concentration of Zn ion is synthesized at $1200^{\circ}C$ for 6 hrs in air atmosphere by conventional solid reaction method. As a result of the red phosphor $(Y,\;Zn)_2O_3$:$Eu^{3+}$ is measured X-ray diffraction (XRD), The main peak is nearly corresponded to the same as JCPDS card (No. 41-1105). When the doping concentration of Zn ion is more than 5 mol%, However, the ZnO peak is showed by XRD analysis. Therefore, when the doping concentration of Zn ion is less than 5 mol%, the Zn ion is well mixed in $Y_2O_3$ structure without the impurity phases. The photoluminescence (PL) properties is shown as this phosphor is excited in 254 nm region and the highest emission spectra of $(Y,\;Zn)_2O_3$:$Eu^{3+}$ has shown in 612 nm region because of a typical energy transition ($^5D_0{\rightarrow}^7F_2$) of $Eu^{3+}$ ion. As the doping concentration of Zn ion is more than 10 mol%, the emission peak is suddenly decreased. when the highest emission peak as doping concentration of Zn ion is shown, the composition of this phosphor is $(Y_{0.95},\;Zn_{0.05})_2O_3$:$Eu^{3+}_{0.075}$ and the particle size analyzed by FE-SEM is confirmed from 0.4 to $3{\mu}m$.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.513-517
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• 2013

This study focused on the synthesis of $Nb_xSrTi_{1-x}O_3$ photocatalysts which partially inserted Nb ions with excellent ability of fluorescence into the perovskite structured $SrTiO_3$ frameworks and their photocatalytic hydrogen productions from methanol/water splitting corresponding to the molar ratios of Ti and Nb. The characteristics of the synthesized $SrTiO_3$ and $Nb_xSrTi_{1-x}O_3$ powders were analyzed by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), and UV-Visible spectrometer. The hydrogen evolution from methanol/water photo-splitting was enhanced over $Nb_{0.05}SrTi_{0.95}O_3$ compared to those over $SrTiO_3$ and another $Nb_xSrTi_{1-x}O_3$; 4.9 mL of hydrogen gases was collected after 8 h when 0.5g of $Nb_{0.05}SrTi_{0.95}O_3$ catalyst was used in pH 10.

• Journal of Conservation Science
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• v.34 no.5
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• pp.333-343
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• 2018

This study was conducted to evaluate the conservation environment by monitoring temperature and humidity for two years and mapping the remaining pigments of mural paintings to diagnose the conservation state of mural paintings of Royal Tombs in Neungsan-ri. We evaluated the characteristics of condensation in the tomb. Compared with the results of a 2008 survey, we conducted state change of mural paintings in the tomb. The temperature in the main room, which has an annual average soil temperature distribution at 5 m depth in Korea, is maintained at $13{\sim}18^{\circ}C$. The temperature range of the main room was between less than $0.1^{\circ}C$ to $0.5^{\circ}C$, and the diurnal variation of temperature between summer (June to September) and winter (December to January) is the greatest. Condensation is more concentrated in the summer because the outdoor air was typically at higher temperatures than the main room inflows in the tomb. Mapping the remaining pigment composition and particle distribution of mural paintings showed that it was in the range of 36.72~39.53% of the wall area. The pigment range was confirmed to be the same as it was in 2008, through ultraviolet fluorescence reaction and infrared ray investigation. Therefore, the underground environment that receives dew condensation in the summer has been stable since 2008. However, continuous monitoring is needed because the deterioration of mural painting proceeds considerably after excavation and only a small percentage of the pigments survive.