• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.59-62
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• 2019

Y2O3-MgO nanocomposites are promising materials for hypersonic infrared windows and domes due to their excellent midIR transmittance and mechanical properties. In this work, influence of SPS heating rate on the microstructure, IR transmittance, and mechanical properties of Y2O3-MgO nanocomposites was investigated. It was found that the average grain size decreases with a decreasing heating rate, which can be attributed to high defect concentration by rapid heating and deformation during densification. Also, the residual porosity decreases with a decreasing heating rate, which is ascribed to the enhancement of grain boundary diffusion by a large grain-boundary area (a small grain size). Consequently, high transmittance and hardness were attained by the low heating rate. On the other hand, the mechanical strength showed little difference with the heating rate change, which is somewhat different from the general knowledge on ceramics and will be discussed in this letter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.21-23
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• 1994

By adding La₂O₃ to optical multicomponent glass composition, after making mother glass and core fiber that enable to enlarge the infrared transmittance region, then surveyed the optical properties. Through thermal analysis of the glass abstained by melt-quenching after selecting stable basic composition on devitrification and replace SiO₂ by 4-12wt% La₂O₃. As La₂O₃ increases up to l2wt% transition temperature, refractive index, density, deformation temperature increased, whereas thermal expansion coefficient decreased. As a result of inspectig transmittance in UV/VIS/IR region, visable region indicated the decrease of transmittance by increasing the La₂O₃ and transmittance region was enlarged by increasing the La₂O₃ in IR region. Also, fabricate core fiber at 820℃ and severy the optical loss we could fact that La₂O₃ composition added 12wt% showed the minimum optical loss.

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.107.2-108
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• 2001

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.88-91
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• 2003

Electromagnetic interference shielding and near-infrared cutoff filters for plasma display panel application were designed and fabricated by radio frequency magnetron sputtering. Three types of the filters were prepared: the basic structure of type A consisted of [$TiO_2$ Ti Ag $TiO_2$]; type B, of [$TiO_2$ ITO Ag $TiO_2$]; type C, of [$TiO_2$ ITO Ag ITO $TiO_2$]. Ti and ITO layers deposited on Ag layers were employed as barriers to prevent the oxidation and the diffusion of Ag film into the adjacent oxide layers. Optical, electrical, chemical, and structural properties were investigated, and the result shows that the filters with the ITO barrier layers provided an enhancement in transmittance in the visible owing to a lower absorption of ITO layers than Ti layers. Type C filter showed better optical and electrical performances and smoother surface roughness than Type B and C filters: the average sheet resistance was as low as 1.51 $\Omega\Box$ (where $\square$ stands for a square film), the peak transmittance in the visible was as high as 78.2 %, and the average surface roughness was 1.48 nm.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.82-89
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• 2014

The damage in germanium (Ge) optical window irradiated by a near-infrared continuous wave (CW) laser was studied. Laser-induced heating and melting process were surveyed, and the specific laser power and the irradiance time to melt were estimated by numerical simulation. The experiments were also carried out to investigate the macro and micro structure change on Ge window. Results showed that the surface deformation was formed by melting and resolidification process, the damaged surface had a polycrystalline phase, and the transmittance as an optical performance factor in mid-infrared region was decreased. We confirmed that an abnormal polycrystalline phase and surface deformation effect such as hillock formation and roughness increase reduced the transmittance of Ge window and were the damage mechanism of CW laser induced damage on Ge window.

• Journal of Technologic Dentistry
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• v.34 no.1
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• pp.1-9
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• 2012

Purpose: The purpose of this study was to investigate the transmittance differences of pressable ceramic core due to thickness within the visible light spectrum. Methods: 36 specimens were divided into 2 groups (0.6mm, 0.8mm) which have each 3 specimens. The size of specimens was 10mm high and 10mm wide. The transmittance of specimens are measured by spectrophotometer Model Cary 500 that can measure infrared-ray, visible wave and ultraviolet-ray. Results: The results shows that there was no significant difference between specimen's thickness(0.6mm, 0.8mm) and transmittance. Conclusion: The individual's color perception is personal and there are numerous factors that influence on it. In general, human eye can perceive the color of thing only within visible light spectrum but in this experiment through spectrophotometer there was no big difference between specimen's thickness(0.6mm, 0.8mm) and transmittance. To sum up, The most important factors were a layed porcelain structure and its thickness rather than core thickness in the porcelain crown. Also, When making all ceramic core with dead pulp (nervous treatment tooth) when used as a restorative esthetic think is more efficient to improve.

• Journal of Technologic Dentistry
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• v.33 no.2
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• pp.129-136
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• 2011

Purpose: The purpose of this study was to investigate the transmittance differences of zirconium core due to thickness within the visible light spectrum. Methods: 36 specimens were divided into 3 groups (0.6mm, 0.8mm, 1.0mm) which have each 12 specimens. The size of specimens was 10mm high and 10mm wide. The transmittance of specimens are measured by spectrophotometer Model Cary 500 that can measure infrared-ray, visible wave and ultraviolet-ray. Results: The results shows that there was no significant difference between specimen's thickness and transmittance. Conclusion: The individual's color perception is personal and there are numerous factors that influence on it. In general, human eye can perceive the color of thing only within visible light spectrum but in this experiment through spectrophotometer there was no big difference between specimen's thickness and transmittance. To sum up, The most important factors were a layed porcelain structure and its thickness rather than core thickness in the porcelain crown.

• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.331-336
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• 2021

The Non-dispersive Infrared (NDIR) gas sensor has high selectivity, measurement reliability, and long lifespan. Thus, even though the NDIR gas sensor is expensive, it is still widely used for carbon dioxide (CO₂) detection. In this study, to reduce the cost of the NDIR CO₂ gas sensor, we proposed the new optical waveguide structure design based on ready-made gas pipes that can improve the sensitivity by increasing the initial light intensity. The new optical waveguide design is a structure in which a part of the optical waveguide filter is inclined to increase the transmittance of the filter, and a parabolic mirror is installed at the rear end of the filter to focus the infrared rays passing through the filter to the detector. In order to examine the output characteristics of the new optical waveguide structure design, optical simulation was performed for two types of IR-source. As a result, the new optical waveguide structure can improve the sensitivity of the NDIR CO₂ gas sensor by making the infrared rays perpendicular to the filter, increasing the filter transmittance.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.1-11
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• 2015

In this study, an online seed potato sorting system using a visible and near infrared (40 1100 nm) transmittance spectral technique and statistical model was evaluated for the nondestructive determination of infected and sound seed potatoes. Seed potatoes that had been artificially infected with Pectobacterium atrosepticum, which is known to cause a soil borne disease infection, were prepared for the experiments. After acquiring transmittance spectra from sound and infected seed potatoes, a determination algorithm for detecting infected seed potatoes was developed using the partial least square discriminant analysis method. The coefficient of determination($R^2_p$) of the prediction model was 0.943, and the classification accuracy was above 99% (n = 80) for discriminating diseased seed potatoes from sound ones. This online sorting system has good potential for developing a technique to detect agricultural products that are infected and contaminated by pathogens.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.5
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• pp.672-679
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• 2014

To improve sensing capability of infrared, heat-resistance and mechanical properties, the $SiO_2$ and $TiO_2$ anti-reflective layers were coated on sapphire substrate by MOCVD. The standard wavelength was 4,600nm, and the thickness of anti-reflective layers were 379 and 758nm in case of ${\lambda}/4$ and ${\lambda}/2$ of incident angle($65^{\circ}$), respectively. The $SiO_2$ and $TiO_2$ anti-reflective layers were coated 12.6 and 9.7nm/min of deposition rates by increasing oxygen pressure to set the ideal refractive index of 1.283. In case of $SiO_2({\lambda}/2)$ coating, the transmittance increased from 55.0 to 62.7%. The transmittance of $TiO_2({\lambda}/2)$ anti-reflective layer also increased from 55.0 to 64.8%. The flexural strength of $SiO_2({\lambda}/2)$ and $TiO_2({\lambda}/2)$ layer coated sapphire increased from 337.8 to 362.9 and 371.8MPa, respectively. The flexural strength at $500^{\circ}C$ of these materials also increased respectively to 304.5, 358.2MPa from 265.9MPa. From these results, we confirmed these materials can be used as transmission window of infrared light.