• Korean Journal of Materials Research
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• v.22 no.12
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• pp.669-674
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• 2012

Yellow phosphor dispersed color conversion glasses are promising phosphor materials for white LED applications because of their good thermal durability, chemical stability, and anti-ultraviolet property. Six color conversion glasses were prepared with high Tg and low Tg specimens of glass. Luminous efficacy, luminance, CIE (Commission Internationale de l'Eclairage) chromaticity, CCT (Correlated Color Temperature), and CRI (Color Rendering Index) of the color conversion glasses were analyzed according to the PL spectrum. Color conversion glasses with high Tg glass frit, sintered at higher temperature, showed better luminous properties than did color conversion glasses with low Tg glass frit. The characteristics of the color conversion glass depended on the glass composition rather than on the sintering temperature. The XRD peaks of the YAG phosphor disappeared in the color conversion glass with major components of $B_2O_3$-ZnO-$SiO_2$-CaO and, in the XRD results, new crystalline peaks of $BaSi_2O_5$ appeared in the color conversion glass with major components of $Bi_2O_3$-ZnO-$B_2O_3$-MgO. The characteristics of CIE chromaticity, CCT, and the CRI of low Tg color conversion glasses showed worse color properties than those of high Tg color conversion glasses. However, these color characteristics of low Tg glasses were improved by thickness variation. So color conversion glasses with good characteristics of both luminous and color properties were attained.

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1022-1034
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• 1999

A relation between composition and properties of Na2O-Al2O3-SiO2 glasses was investigated with application of the extreme vertical design. Properties investigated in this study include glass transition temperature density refractive index thermal expansion electrical conductivity bending strength and hardness, Most of the quadratic models fitted on property data were statistically significant. The properties estimated from the fitted equation agreed well with the measured properties. The estimated properties were compared with those reported by other investigators. Additional composition except for those of extreme vertices were needed to yield a slightly better result for the simple system such as a temary system. In addition an optimal composition on each property could be calculated by using optimization technique on result obtained from the fitted quadratic models.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.75-81
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• 2013

We fabricated translucent opal glass to replace the polycarbonate diffuser in LED lighting systems in order to solve the durability problem. Batch materials of opal glass with a composition of calcium phosphate were created and melted at $1550^{\circ}C$, and the effect of opaqueness was identified by an addition of 1~7% calcium phosphate as an opacifier raw material. As a result, translucent opal glass was obtained by the melting of the mixed batch materials with a composition of more than 5% calcium phosphate glass at $1550^{\circ}C$ for 2 hrs, which had excellent optical properties for the diffuser of a LED lighting system with no dazzling from direct light by a high haze value exceeding 90% and a low parallel transmittance value of about 5%. For the thermal properties, the thermal expansion coefficient was found to be $5.6{\sim}5.9{\times}10^{-6}/^{\circ}C$ and the softening point was $874{\sim}884^{\circ}C$. In addition, good thermal properties such as good thermal shock resistance and feasibility for use with a general manufacturing process during the forming of glass tubes and bulbs were noted. Therefore, it is concluded that this translucent opal glass can be used as a glass diffuser material for LED lighting due to its high heat resistance and high durability as a replacement for a polycarbonate diffuser.

• Journal of the Korean Ceramic Society
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• v.16 no.2
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• pp.83-88
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• 1979

The Anorthite is useful compound for some ceramic industries but it is difficult to produce Anorthite because of its high melting point (1553$^{\circ}C$) and narrow firing range. On this study, glass frit was added to Anorthite batch composition to widen firing range and lower melting point. After mixing a glass frit $(Na_2O-CaO-6SiO_2)$ with Anorthite, it was melted and quenched. Ratio of Anorthite vs. glass frit was 9 : 1, 8.5 : 1.5, 8 : 2, 7.5 : 2.5, 7 : 3. In those batch composition added amount of $No_2O$ were between 1.3wt.% and 3.9wt.%. To find the thermal change of the quenched, D.T.A. was surveyed. The quenched were fired at various vitrification temperature and detected by X-Raydiffraction analysis. With addition of glass frit, firing range and vitrification temperature of Anorthite was 100~15$0^{\circ}C$ and 1050~115$0^{\circ}C$ respectively. Optimum amount of glass frit was 20wt.% for the upper mentioned.

• Journal of Korean Society for Quality Management
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• v.16 no.1
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• pp.1-7
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• 1988

The most important element upon the quality of family glass products is the color of glass, which is the first object of consumers concern in purchasing. Therefore, colorless and transparent color tone can level up the additional value of the products. But we have produced the glass products in a large quantity by using the automatic tank brazier, chronic problem has been left over the color tone. By compounding and analizing the management techniques applied by peculiar technique and design of experiments pertinently, and by adjusting the decoloring composition ratio, we can contribute to improvement of color tone as well as to the cost reduction by diminishing the unnecessary decoloring agent. Intangible effect was the securing the superiority of quality home and abroad with the improvement of color tone and was taking a triangular position the factors influencing the glass decoloring which had been an unexhausted field. Tangible effect was the reduction of decoloring cost by diminishing the unnecessary oxidant. We registered the optimal composition ratio condition which was searched by applicating the design of experiments. To maintain good color tone, we manage the degree of purity, the most important thing among the items of color tone, continuously by control chart and it has maintained steady state now.

• Fire Science and Engineering
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• v.16 no.4
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• pp.65-71
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• 2002

In this paper, the thermal and flame properties of GFRP with various flame retardant(aluminum trihydrate, antimony trioxide) compositions have been investigated by thermal analysis and flammability tests(LOI test, flammability 45 degree test). The flame and mechanical properties(hardness, tensile strength, modulus) of general purpose grade glass fiber/unsaturated polyester composite with flame retardant composition have been also evaluated. The effect of cure pressure on the flame properties of aerospace grade glass fiber/epoxy composite was investigated. Considering the flame and mechanical property of composite, we could determine the optimum flame retardant composition(ATH 10∼20 phr). Test results show that the flame property of glass fiber/epoxy composite is considerably affected by cure pressure conditions.

• Journal of the Korean Ceramic Society
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• v.43 no.5 s.288
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• pp.293-298
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• 2006

For substrate glass applied to PDP (Plasma Display Panel), it has been developed many glass compositions that have to not only meet the specifications of PDP but also satisfy the float process as production technology. In the present work several compositions with no deformation at PDP processing temperature and thermal expansion coefficient of $83{\sim}9{\times}10^{-7}/K$ were designed. Based on viscosity at high temperature and liquidus temperature for those compositions, three candidate compositions named T-2, T-4, T-6 were selected finally. It was examined additionally that thermal shrinkage at PDP processing temperature and visible transmittance. The properties of T-series were compared with those of commercial glasses and discussed from the view point of PDP device and glass production.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2025-2037
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• 2021

The influence of lead cations on natural quartz (QZ) from Egypt as a glass shielding material for the composition with nominal formula (10Na₂O - (90 - x) QZ - xPbO (where x = 30, 35, 40, 45 and 50 mol %)) was examined. The studied samples are synthesized via the melt quenching method at 1050 ℃. The X-ray diffraction XRD patterns were confirmed the glass nature for studied samples. Moreover, the optical properties, and the transparency for all compositions were examined by UV-Vis spectroscopy. Also, the major elemental composition of the natural quartz were estimated via the X-ray fluorescence (XRF) technique. Further, the density and molar volume were determined. Furthermore, the nuclear shielding parameters such as, mass attenuation coefficient, effective atomic number, electronic density, the total atomic, and electronic cross sections as well as the mean free path, and the half value layer with different gamma ray energies (81 keV-1407 keV) were calculated. Besides, the results showed that the shielding behavior towards the gamma ray radiation for all glass samples was increased as the increment in PbO concentration in the glass system.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1456-1463
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• 2022

The aim of this work is to study the radiation shielding properties of cement samples with waste glass incortated into its composition. The mass attenuation coefficient (MAC) of the samples were experimentally determined to evaluate their radiation shielding ability. The experimental coefficient was evaluated using NaI detector for gamma energies between 59.53 keV and 1408.01 keV using different radioactive point sources Am-241, Eu-152, Co-60, and Cs-137, and the gamma transmission parameters half-value layer, mean free path, and transmission factor were calculated. The theoretical coefficient of the composites was determined using Geant4 and XCOM software. The results were also compared against Geant4 and XCOM simulations by calculating the relative deviation between the values to determine the accuracy of the results. In addition the mechanical properties (including Compressive and porosity) as well as the thermogravimetric analysis were tested for the present samples. Overall, it was concluded that the cement sample with 50% waste glass has the greatest shielding potential for radiation shielding applications and is a useful way to reuse waste glass.

• Journal of Conservation Science
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• v.35 no.2
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• pp.169-176
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• 2019

The material composition of 19 ornaments used for women's hats in the late $19^{th}$ century to $20^{th}$ century, which are kept at National Folk Museum of Korea, was analyzed using SEM-EDS. Sixteen ornaments were composed of $Na_2O$ and PbO, which form adifferent lead glass from those that have been excavated or handed down since ancient times in Korea. The chemical composition analysis has confirmed that two ornaments belong to the mixed alkali glass, while one belongs to the potash glass IIItype. This lead glass is similar in composition to the Japanese craft lead glass that was imported to Joseon during the Japanese colonial era. It is estimated that the lead glass ornaments used in women's hats in the late $19^{th}$ century to $20^{th}$ century were made from raw materials imported from Japan or made from lead glass used for crafts in Japan. This shows that jewelry such as jade and amber, which have been traditionally used in the modern and present ages, have been replaced by craft lead glass imported from Japan.