• Polymer(Korea)
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• v.36 no.6
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• pp.733-738
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• 2012

The effect of glass bead and glass fiber on the enhancement of dimensional stability in poly(ethylene naphthalate) (PEN) flexible substrate for photovoltaic devices has been studied. It was found that the coefficient of thermal expansion (CTE) and the optical transmittance decreased with increasing inorganic filler content. In addition to filler contents, the size and size distribution of fillers are the other important factors to improve CTE and optical transmittance of PEN film. Our results showed that the optimum filler content was found to be about 5 wt% to enhance the dimensional stability of PEN by more than 50% with maintaining the optical transmittance over 85% for the flexible substrate.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.2
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• pp.93-99
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• 2002

This study was performed to investigate the color stability of IPS Empress 2 glass-ceramic after heat-pressing and/or heat-treatments. Three types of IPS Empress 2 ingots (shade 100, 300, 500) were tested. For this study, three groups were prepared as follows: group 1 is as-received material, group 2 is heat-pressed material, and group 3 is fully heat -treated material. The color of the specimens was measured with a colorimeter. The data were statistically evaluated with one-way ANOVA and Scheffe's multiple test. The results obtained were as follows: 1. IPS Empress 2 glass-ceramic demonstrated less color stability according as the shade is lighter. Namely, the shade 500 showed the lowest color shifts and the shade 100 showed the greatest color shifts after heat-pressing and heat-treatments. 2. In the cases of shade 100 and 300, the changes of ${\Delta}E^*$ were affected mostly by the changes of $L^*$ and $b^*$. 3. In ${\Delta}E^*$ of the shade 100, there were significant differences among the group 1, 2, and 3 (P<0.001). 4. In ${\Delta}E^*$ of the shade 300, there were significant differences between the group 1 and 2, and the group 1 and 3 (P<0.001). 5. In ${\Delta}E^*$ of the shade 500, there was significant difference only between the group 1 and 3 (P<0.001).

• Current Optics and Photonics
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• v.4 no.1
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• pp.44-49
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• 2020

In this paper, a new method is presented to measure the refractive index of single plain glass or multilayered materials, based on a laser frequency-shifted confocal feedback microscope. Combining the laser frequency-shifted feedback technique and the confocal effect, the method can attain high axial-positioning accuracy, stability and sensitivity. Measurements of different samples are given, including N-BK7 glass, Silica plain glass, and a microfluidic chip with four layers. The results for N-BK7 glass and Silica plain glass show that the measurement uncertainty in the refractive index is better than 0.001. Meanwhile, the feasibility of this method for multilayered materials is tested. Compared to conventional methods, this system is more compact and has less difficulty in sample processing, and thus is promising for applications in the area of refractive-index measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.11
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• pp.1050-1054
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• 2006

There have been intensive and continuous efforts in the field of DLC coating process because of their feature, like high hardness, high elasticity, abrasion resistance and chemical stability and have been applied widely the industrial areas. In this research, optimal grinding condition was investigated using Microlens Process Machine for the development of aspheric glass lens which is to be used for mobile phone module with 3 mega pixel and 2.5X optical zoom, and tungsten carbide(WC) mold cote was manufactured using high performance ultra precision machining and the effects of DLC coating on the form accuracy(PV) and surface roughness(Ra) of WC mold core was evaluated.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1057-1058
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• 2006

The preparation of $Ti_{50}Cu_{28}Ni_{15}Sn_7$ metallic glass composite powders was accomplished by the mechanical alloying of a pure Ti, Cu, Ni, Sn and carbon nanotube (CNT) powder mixture after 8 h milling. In the ball-milled composites, the initial CNT particles were dissolved in the Ti-based alloy glassy matrix. The bulk metallic glass composite was successfully prepared by vacuum hot pressing the as-milled CNT/$Ti_{50}Cu_{28}Ni_{15}Sn_7$ metallic glass composite powders. A significant hardness increase with the CNT additions was observed for the consolidated composite compacts.

• Journal of the Korean Wood Science and Technology
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• v.47 no.4
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• pp.472-485
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• 2019

When wood plastic composites (WPCs) have been used for a certain period of time, they become waste materials and should be recycled to reduce their environmental impact. Waste WPCs can be transformed into reinforced composites, in which fillers are used to improve their performance. In this study, recycled WPCs were prepared using different proportions of waste WPCs, nanoclay, and glass fiber. The effects of nanoclay and glass fiber on the microstructural, mechanical, thermal, and water absorption properties of the recycled WPCs were investigated. X-ray diffraction showed that the nanoclay intercalates in the WPCs. Additionally, scanning electron micrographs revealed that the glass fiber is adequately dispersed. According to the analysis of mechanical properties, the simultaneous incorporation of nanoclay and glass fiber improved both tensile and flexural strengths. However, as the amount of fillers increases, their dispersion becomes limited and the tensile and flexural modulus were not further improved. The synergistic effect of nanoclay and glass fiber in recycled WPCs enhanced the thermal stability and crystallinity ($X_c$). Also, the presence of nanoclay improved the water absorption properties. The results suggested that recycled WPCs reinforced with nanoclay and glass fiber improved the deteriorated performance, showing the potential of recycled waste WPCs.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.54-59
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• 2021

In this work, narrow-band green-emitting CsPbBr3 particles are embedded in commercialized glass composites by a facile dry process. By optimizing the method through sintering in glass frit (GF) composites including CsBr and PbBr2, used as precursors, the encapsulation of CsPbBr3 particles made them waterproof with green fluorescence. To improve the fluorescent properties by reducing aggregation of CsPbBr3, fumed silica (FS) is additionally used to help particles avoid bulking up in the glass matrix. The CsPbBr3 perovskite/glass composites are characterized using scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDS) maps, which support the existence of CsPbBr3 particles in the glass matrix. The photoluminescence (PL) properties demonstrate that the emission spectrum peak, full width at half maximum (FWHM), and photoluminescence quantum yield (PLQY) values are 519 nm, 17 nm, and 17.7 %. We also confirm the water-resistant properties. To enhance water/moisture stability, the composite sample is put directly into water, with its PLQY monitored periodically under UV light.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1042-1046
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• 2007

In this study, we investigated the mechanism responsible for the thermal stability of CoSi by addition of a foreign chemical element. Addition of W was found to increase the heat of formation of CoSi. This increase was claimed to inhibit the glass formation, which is preferred by silicide formation kinetics depicted by the maximum system energy degradation rate. In this case, there forms at the interface between CoSi and Si wafer a crystalline structure, the effective diffusion coefficient of which is much less than the self-diffusion rate provided by the glass. It was stated that the phase transition requires a higher thermal energy as the consequence, thereby enhancing the thermal stability of CoSi.

• International Journal of Highway Engineering
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• v.18 no.3
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• pp.67-74
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• 2016

PURPOSES : This study evaluated the field applicability and laboratory performance of glass fiber-reinforced asphalt (GFRA) mixtures. METHODS : The general hot-mix asphalt (HMA) and GFRA mixtures were paved in five sites, including three national highways, one express highway, and an arterial road, to evaluate field applicability and durability. The plant mixing and construction method for the GFRA were similar to those for the general HMA. The lab performances of the field samples were relatively compared through the mechanical measures from the Marshall stability, indirect tensile strength, and dynamic stability. The field performance was surveyed after a year. RESULTS : The lab tests verified the superior lab performances of the GFRA compared to the general HMA. The Marshall stability of the GFRA increased for about 128% of the general HMA. The indirect tensile strength of the GFRA was 115% greater than that of the general HMA. The dynamic stability of the GFRA resulted in 16,180 reps/mm, which indicated that high rut resistance may be expected. No noticeable defects, such as cracks or deformation, were observed for the GFRA sections after a year. CONCLUSIONS : The lab tests and field survey for the five GFRA sites resulted in superior performances compared to the general HMA. The relatively low-cost GFRA, which required no pre-processing procedures, such as polymer modification, may be a promising alternative to the polymer-modified asphalt mixtures. The long-term performance will be verified by the superior field durability of the GFRA in the near future.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.6
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• pp.572-576
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• 2002

This investigation was designed to estimate the biaxial flexure strength and fracture toughness of lithium disilicate glass-ceramics of IPS Empress 2 system pressed with as-received ingots and their sprue buttons. Two groups of the lithium disilicate glass-ceramics were prepared as follows: group 1 is ingot-pressed group; group 2 is sprue button-pressed group. A ball-on-three-ball test was used to determine biaxial flexure strength (BFS) of disks in wet environment. Scanning electron microscopy(SEM) analysis was conducted to observe the microstructure of the ceramics. Unpaired t-test showed that there were no differences in the mean biaxial Hem strength (BFS) and KIC values between group 1 and 2 (p > 0.05). Two groups showed similar values in the KIC and the strength at 5% failure probability. The SEM micrographs of the IPS Empress 2 glass-ceramic showed a closely packed, multi-directionally interlocking pattern of numerous lithium disilicate crystals protruding from the glass matrix. The lithium orthophosphate crystals could not be observed on the fracture surface etched. There was no a marked difference of the microstructure between group 1 and 2. Although there were no tests including color stability, casting accuracy, etc., the results of this study implied that we could reuse the sprue button of the pressed lithium disilicate glass-ceramic of IPS Empress 2 system.