• Journal of Conservation Science
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• v.29 no.3
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• pp.261-277
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• 2013

This study aims to research the relationship between whitewares and their rare materials from the site of Yanggu and Bunwon through the componential characteristic of the excavated whitewares from the 1st and the 2nd kilns of Chiljeon-ri in Bangsan-myeon, Yanggu-gun. As a result, the sherds were devided according to the chemical compositions of the body and the glaze via their respective production era. However, it considered that the whitewares from Chiljeon-ri had been manufactured with geochemically similar materials and the production process, such as refining and combining materials, had been different. It assumed that the firing temperatures of the whitewares from Chiljeon-ri were around $1,100-1,200^{\circ}C$ and substantially lower than for general whitewares. In the componential analysis, there were disparate properties in the cobalt pigment, which contained trace elements and rare earth elements. A review of the literature revealed a correlation between the whitewares from the late Chosun kiln site in Bunwon-ri and the raw materials from Yanggu-gun, but this was there were various techniques for refining and combining materials in Bunwon-ri.

• Korean Journal of Materials Research
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• v.23 no.5
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• pp.271-275
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• 2013

Cobalt (Co) compounds have been used for centuries to impart rich blue color to glass, glazes and ceramics. Cobalt monoxide (CoO), an oxide of Co, is an inorganic compound that has long been used as a coloring agent in the ceramic industry. Unlike other coloring agents, CoO can be used to develop colors other than blue, and several factors such as its concentration in the glaze and firing condition have been suggested as possible mechanisms. For example, CoO produces a typical blue color called "cobalt blue" at very low concentrations such as 1 wt% in both oxidation and reduction firing conditions; a higher concentration of CoO (5 wt%) develops a darker blue color under the same firing conditions. Interestingly, CoO also develops a purple color at high concentrations above 10 wt%. In this study, we examined the applicability and mechanism of a novel purple glaze containing cobalt(II, III) oxide, one of the well characterized cobalt oxides. Experimental results show that an Augite crystal isoform (Augite-Fe/Co) in which Fe was replaced with Co is the main component contributing to the formation of the purple color. Based on these results, we developed a glaze using chemically synthesized Augite-Fe/Co crystal as a color pigment. Purple color glaze was successfully developed by the addition of 6~15 wt% of $Co_3O_4$ to magnesia lime.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.226-232
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• 2002

We searched thermal stability of ${\alpha}-Fe_2O_3$ using red color filter for display. In the PDP(Plasma Display Panel), the color filter layer is lied normally between front glass and transparent dielectric materials, so it might be needed to study the reaction of ${\alpha}-Fe_2O_3$ and transparent dielectric materials. The transparent dielectric materials containing ZnO has good transparency. Red colorlayer of ${\alpha}-Fe_2O_3$ contacted with dielectric material layer containing ZnO is changed to colorlessness over 500$^{\circ}$C because ZnO defuse ${\alpha}-Fe_2O_3$, the dielectric materials without ZnO, however, maintain red color at the same condition. We suggest that a layer contacting with ${\alpha}-Fe_2O_3$ red color layer has to lie with transparent dielectric materials without ZnO, then the materials containing ZnO is coated over to get color of ${\alpha}-Fe_2O_3$ for red color filter

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1115-1122
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• 2001

The tendency of the miximum brightness of $Y_2$O$_3$:Eu phosphor with various activator concentration, by different surface treatment methods as well as different exciting energies were investigated. The surface treatment methods were the adsorption method used $\alpha$-Fe$_2$O$_3$powder prepared emulsion-drying process and the precipitation method used FeSO$_4$/ethanol. Eu concentration of maximum brightness of $Y_2$O$_3$:Eu phosphor prepared by solid-solid state was changed with various exciting energies. The concentrations were 0.02 mol at VUV(147 nm) as well as 400 V and 0.03 mol at 5 kV. The phosphor treated both by adsorption method and precipitation method showed decreasing luminescent intensity with increasing amount of $\alpha$-Fe$_2$O$_3$, and the methods are chosen by exciting energy. Adsorption method was effective in a low voltage and VUV(147nm) region, and precipitation method was effective in the high voltage region.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.2
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• pp.159-167
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• 2023

Titanium dioxide (TiO₂) is commonly used in sunscreen formulations to protect the skin surface and prevent the penetration of harmful ultraviolet (UV) rays by the physical scattering action of light. However, a disadvantage of using TiO₂ is that it can cause white turbidity when used on skin due to its inactive mineral ingredient. In addition, when TiO₂ particles are reduced to nanosize to eliminate opacity, they can increase the transmittance of visible light and reduce whitening, but may lead to serious skin problems, such as allergic inflammation. To overcome these issues, the bandgap of TiO₂ was controlled by adjusting the amount of oxygen defect and nitrogen amount, resulting in color TiO₂ tailored to the skin. This innovative technology can reduce the whitening phenomenon and effectively block blue light, which is known to cause skin aging by inducing active oxygen. The bandgap controlled TiO₂ compounds proposed in this study are hypoallergenic, broad-spectrum, and environmentally friendly. Furthermore, these compounds have been shown to significantly enhance sun protection factor (SPF) of sunscreens, demonstrating their compatibility with blue light blocking products.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.47-54
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• 2020

To develop the bright-vivid red- and yellow-inorganic fluorescent pigments with high luminescence properties, A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments were synthesized by a water assisted solid state reaction (WASSR) method and a conventional solid state reaction method. Although impurity peaks corresponding to the AVO₃ and AV₃O₈ (A = K, Rb, and Cs) were observed in all samples prepared, the trigonal structure A₃V₅O₁₄ (A = K and Rb) and orthorhombic structure Cs₂V₄O₁₁ were successfully obtained as a main phase. These inorganic pigments showed the broad absorption band (under 550 nm) originated from CT transitions of VO₄ polyhedron, and the strong broad red- and green-emission bands due to ³T₂ → ¹A₁ and ³T₁ → ¹A₁ transitions of the [VO₄]^3- group. The A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ pigments showed a bright-vivid red- and yellow-body color, where the a* values of the A₃V₅O₁₄ (A = K and Rb) were +35.5 and +45.9, respectively, and b* value of Cs₂V₄O₁₁ pigments was +50.3. The L* values of the A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments were over +45. These results indicate that the A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments could be an attractive candidate as a bright-vivid red- and yellow inorganic pigments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.317-327
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• 2013

Air pollution and artificial heat of urban areas have caused the urban heat island in which asphalt pavements absorb solar heat during the daytime and release the heat at night. Hence, in order to improve the environment of urban areas, it is necessary to examine cooling pavements that can reduce heat on road pavements in urban areas. The application of temperature insulation paints on road pavements require to reduce black brightness for visibility, to increase the reflection rate of infrared light and minimize the reflection rate of visible light. In the study, one part of Acrylic-emulsion was used as a main binder, and the changes in black brightness and the changes of addition ratio (0%, 15%, 30%) of hollow ceramics, as well as kinds of paints (carbon black pigment, mixed mineral pigment) were selected as the main experimental factors. The performance of temperature reduction of cooling pavements was analyzed through the reflection rate of spectrum, the reflection rate of solar heat, and the lamp test. Abrasion resistance, UV accelerated weather resistance, and sliding resistance were tested in real situations. In addition, the performance of heat reduction of testing pavements covered with high-reflection paints was analyzed by using an infrared camera. As the test results, when using mixed mineral paints and hollow ceramic of 30%, the reflection rate of spectrum was 43% in the area of near-infrared ray and 17% in the area of visible light at black brightness of $L^*$=42.89 and the reflection rate of solar heat was 27.5%. Total color difference was ${\Delta}E$=0.27 in the test of UV Accelerated Weather Resistance, indicating almost no changes in color. BPN was more than 53 when scattering #2 and #4 silica sand of more than $0.12kg/m^2$. In Taber's abrasion resistance test, abrasion loss was up to 86.4mg at 500 rotations. The performance of heat reduction was evaluated using an infrared camera at the test section applying high-reflection paints to asphalt pavements, in which the results showed that the temperature was reduced by $12.7^{\circ}C$ on CI-30-40 cooling pavements ($L^*$=38.76) and by $14.2^{\circ}C$ on CI-30-60 cooling pavements ($L^*$=57.12).