• Current Optics and Photonics
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• 제3권5호
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• pp.423-428
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• 2019

Visibility of road-surface markings is one of the critical issues that should be secured for self-driving cars as well as human drivers. Glass beads are taking on the role of retroreflectors, and therefore are considered a necessity in modern pavements. In this context, retroreflectance is sensitively dependent not only on the refractive index of glass beads but also on that of the surrounding medium. This implies that the optimum refractive index of glass beads immersed in water, i.e. under wet conditions, is different from that of glass beads surrounded by air, i.e. under dry conditions. A refractive index of approximately 1.9, which is known to maximize retroreflectance under dry conditions, actually exhibits much poorer retroreflectance under wet conditions. This suggests that glass beads with optimal refractive index for wet conditions need to be installed together with those for dry conditions. We propose a facile but practical model capable of calculating retroreflectance of glass beads surrounded by an arbitrary medium, here water in particular, and experimentally verify its capability of assessing the refractive index of commercial glass beads. Changes in retroreflectance according to the mixing ratio of glass beads with different refractive indices are also discussed, in an effort to propose the proper use of glass beads produced for dry and wet conditions.

• 한국전기전자재료학회논문지
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• 제32권6호
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• pp.477-482
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• 2019

This study investigated the influence of the viscoelastic property of slag when producing glass fiber, MFS631 with 60% of manganese slag, 30% of steel slag, and 10% of silica stone. To fabricate the MFS631 glass bulk, slag materials were placed in an alumina crucible, melted at $1,550^{\circ}C$ for 2 h, and then annealed at $600^{\circ}C$ for 2 h. It was found that glass is non-crystalline through X-ray diffraction analysis. MFS631 fiber was produced at speed in the range of 100~300 rpm at $1,150^{\circ}C$. The loss modulus (G") and storage modulus (G') of the produced glass fiber were evaluated at high temperatures. G' and G" of MFS631 were greater than $893^{\circ}C$, and the modulus value was 136,860 pa. This is similar to the results of a general E-glass fiber graph. Therefore, it was concluded that its spinnability is similar to that of E-glass fiber; therefore, it can be commercialized.

• 대한조선학회논문집
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• 제55권5호
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• pp.448-455
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• 2018

Glass wool is an eco-friendly materials that is manufactured through a continuous process by processing waste glass. This materials is low cost compared with another materials and has excellent thermal conductivity. For this reason, glass wool is installed as insulation system for LNG carriers and as insulation of building wall as well as various industries. The mechanism of insulation of glass wool is the conduction of the wool itself and convection by space between fibers. Therefore, in order to develop the enhanced thermal conductivity of glass wool is necessary to reduce its own conduction or to insert additional material after manufacturing as well as prevent convection. In this respect, many researchers have been actively studying to decrease thermal conductivity of polyurethane foam using by inserted glass wool or change the chemical component of glass wool. However, many research are aiming reduction of glass wool itself. This study focus on post-processing and inserted different materials; silica-aerogel, kevlar fiber 1mm, 6mm and glass bubble. Experimental results show that the thermal conductivity almost decreases with the addiction of glass bubble and silica aerogel.

• 한국재료학회지
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• 제27권1호
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• pp.43-47
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• 2017

E (Electric) -glass fibers are the most widely used glass fibers, taking up 90 % of the long glass fiber market. However, very few papers have appeared on the physical characteristics of E-glass fibers and how they depend on the fiberizing temperature of fiber spinning. Glass fiber was fabricated via continuous spinning process using bulk E-glass. In order to fabricate the E-glass specimen, raw materials were put into a Pt crucible and melted at $1550^{\circ}C$ for 2hrs; mixture was then annealed at $621{\pm}10^{\circ}C$ for 2hrs. The transmittance and adaptable temperature for spinning of the bulk marble glass were characterized using a UV-visible spectrometer and a viscometer. Continuous spinning was carried out using direct melting spinning equipment as a function of the fiberizing temperature in the range of $1175{\sim}1250^{\circ}C$, while the winder speed was fixed at 500 rpm. Subsequently we investigated the physical properties of the E-glass fiber. The average diameter of the synthesized glass fiber was measured by optical microscope. The mechanical properties of the fiber were confirmed using a UTM (universal materials testing machine); the maximum tensile strength was measured and found to be $1843{\pm}449MPa$ at $1225^{\circ}C$.

• 한국세라믹학회지
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• 제42권12호
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• pp.842-845
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• 2005

Glass composites containing ceramic fiber have been developed for Solid Oxide Fuel Cell (SOFC) seals. Effect of glass type, loading pressure and thermal cycle the leak rates of composite seals was investigated. Seal performance of two commercial glasses was compared with that of $SiO_2BaO-B_2O_3$ glass synthesized in this work. The leak rate for seals made of pyrex(R) increases from $\~0.0005\;to\;\~0.004sccm/cm$ as the gas pressure increases from 10 to 50 kPa. The soda lime silicate glass seal shows the leak rate two times higher than the one made of pyrex(R) or $SiO_2BaO-B_2O_3$ glass. The viscosity of glass at the seal test temperature is presumed to affect the leak rate of the glass seal. As the applied loading pressure increases from 0.4 to 0.8 MPa at $750^{\circ}C$, the leak rate decreases from 0.038 to 0.024 sccm/cm for composite seals. It has been found that during 50 thermal cycles between $450^{\circ}C\;to\;700^{\circ}C$ leak rates remained almost constant, ranging from 0.025 to 0.03sccm/cm. The results showed an excellent thermal cycle stability as well as sealability of the glass matrix ceramic fiber composite seals.

• 한국세라믹학회지
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• 제49권1호
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• pp.100-104
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• 2012

Barium zincoborate (BZB) glass was added to $Ba_{0.5}Sr_{0.5}TiO_3$, and sintered at $875^{\circ}C$ for 2 h in air. When the BZB glass was added in quantities ranging from 15 to 20 wt%, the relative bulk density ranged from 93.1% to 94.2%, while the density decreased to roughly 81% thereafter up to 30 wt% glass addition. Quantitative XRD analysis showed that the $Ba_{0.5}Sr_{0.5}TiO_3$ filler was significantly dissolved into the BZB glass. However, no secondary phase was identified by XRD up to 30 wt% glass addition. The dielectric constant was about 130 to 140 at 1MHz up to 20 wt% BZB glass addition, while it decreased to about 60 thereafter, which may be ascribed to decreased density, partial dissolution of the $Ba_{0.5}Sr_{0.5}TiO_3$, and associated changes in the glass composition. The dielectric loss of the 20 wt% glass added specimen was 0.008.

• 한국세라믹학회지
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• 제50권1호
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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.

• 한국재료학회지
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• 제26권10호
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• pp.549-555
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• 2016

We have investigated a glass-forming region of $V_2O_5-P_2O_5-ZnO$ glass and the effects of the addition of modifier oxides ($B_2O_3$) to the glass systems as a sealing material to improve the adhesion between the glass frits and a soda lime substrate. Thermal properties and coefficient of thermal expansion were measured using a differential scanning calorimetry, a dilatometer and a hot stage microscopy. Structural changes and interfacial reactions between the glass substrate and the glass frit after sintering (at $400^{\circ}C$ for 1 h) were measured by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope. The results showed that the adhesion strength increases as the content of $B_2O_3$ at 5 mol% increases because of changes in the structural properties. It seems that the glass structures change with $B_2O_3$, and the $Si^{4+}$ ions from the substrate are diffused to the sealing glass. From these results, we could understand the mechanism of strengthening of the adhesion of soda lime silica substrate by ion-diffusion from the substrate to the glass.

• 공업화학
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• 제16권3호
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• pp.440-448
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• 2005

폐 유리병을 비롯한 폐 유리들을 대상으로 이들을 세척 또는 불순물의 분리 등 전처리를 하지 않고 건축용 단열재로서 발포유리 제조를 위한 원료로서의 적용 가능성 여부를 타진하기 위하여 폐 병유리, 폐판유리 및 LCD 유리 등의 물리화학적 특성을 조사하였다. 이를 위해서 폐 유리의 화학적 성분 분석, 열분석, 결정학적 분석, 점성, 유변학적 분석을 시행하였으며 이 결과를 바탕으로 정성적인 발포유리 제조도 시도하였다. 모든 분석 및 검토의 결과 및 폐 유리병 및 판유리는 발포유리의 제조 원료로서 충분한 사용가능성을 보여 주었다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2002년도 추계학술발표강연 및 논문개요집
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• pp.107-107
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• 2002