• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.578-581
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• 1999

Dot pattern print methods composed of a diffusion film and two prism sheets, have been generally used for backlighting systems of LCDs. However, this methods require complex structures and show high power consumption and optical loss. To improve these disadvantages of conventional backlight units, light guides using highly scattering optical transmissions (HSOT) polymer as scatters, have been introduced. In this study we analyzed multiple scattering effect in light guide by means of Monte carlo simulation based on Mie scattering theory and ray tracing method. As a result it was revealed that scattering intensity depends on the size of scatters. On the other hands, it was shown that scattering efficiency depends on the wavelength of fluorescent lamp as well as the size of scatters.

• Transactions on Electrical and Electronic Materials
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• v.14 no.1
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• pp.24-27
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• 2013

In this paper, we investigated the effect of luminescence properties of various concentrations of magnesium-doped ZnS:Mn phosphor excited by plasma luminescence device. The PL intensity was evaluated in the range of 300~500 nm excitation wavelengths. We found the highest PL intensity of the phosphors excited by 365 nm and 450 nm was observed at Mg concentrations of 1.4 wt% and 0.8 wt%, respectively. In addition, an emission peak was distinguished at 580 nm wavelength. With increasing Mg dopant level, enhanced PL intensity was observed, which is possibly applicable to color converting materials by blue emission for white light sources. Finally, we evaluated the luminance properties of color converting ZnS:Mn,Mg phosphors with plasma blue light source. the white luminance of plasma light source with CIE(0.36,0.26) was established by color converting phosphors of ZnS:Mn with 0.8 wt% Mg.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.518-521
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• 2002

New luminescent material, 6,11-Dihydroxy-5,12-naphthacenedione$(Alq_2-Ncd)$ was synthesized. And extended efforts have been made to obtain high-performance electro-luminescent(EL) devices, since the first report of organic light-emitting diodes(OLEDs) based on tris-(8-hydroxy-quinoline)aluminum$(Alq_3)$ Current-voltage characteristics, brightness-voltage characteristics, luminous efficiency and quantum efficiency were measured at room temperature. The maximum wavelength of the EL is at around 504nm and the brightness is up to $2702[cd/m^2]$ with the maximum efficiency up to 3.91 [1m/W]. This study indicates not only the sterical effect but also some other effect would be responsible for the change of the emission wavelength.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.49-49
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• 2003

Nanometer sized zinc oxide (ZnO) powder was synthesized by a novel "solution-combustion method" and its photocatalytic activity was evaluated with the recovery of Ag from a used photofilm developing solution. Different parameters affecting the reaction rates like wavelength of the W light used, reaction temperature, mass of the used photocatalyst, and effect of scavenger were tested. The optimum parameters were found as follows. UV wavelength of less than 385nm, reaction temperature between 40- 60 $^{\circ}C$, photocatalyst concentration of 3-6 g/1, and scavenger concentration of 0.3-0.4 g/1.

• Applied Science and Convergence Technology
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• v.24 no.2
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• pp.41-46
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• 2015

Transparent conductive oxides (TCOs) are essential material in optoelectronics such as solar cells, touch screens and light emitting diodes. Particularly TCOs are attractive material for infrared cut off film due to their high transparency in the visible wavelength range and high infrared reflectivity. Among the TCO, Indium tin oxide has been widely used because of the high electrical conductivity and transparency in the visible wavelength region. But ITO has several limitations; expensive and low environmental stability. On the other hands, fluorine doped tin oxide (FTO) is well known for low cost, weather ability and stable in acidic and hydrogen. In this study, two different magnetron sputtering techniques with RF and DC modes at room temperature deposition of FTO thin film was conducted. The change of oxygen content is influence on the topography, transmittance and refractive index.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.901-907
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• 2000

As the minimum feature size for making ULSI approaches the wavelength of light source in optical lithography, the aerial image is so hardly distorted because of the optical proximity effect that the accurate mask image reconstruction on wafer surface is almost impossible. We applied the Optical Proximity Correction(OPC) on isolated patterns assuming Attenuated Phase Shift Mask(APSM) as well as binary mask, to correct the widening of isolated patterns. In this study, we found that applying OPC to APSM shows much better improvement not only in enhancing the resolution and fidelity of t도 images but also in enhancing the process margin than applying OPC to the binary mask. Also, we propose the OPC method of APSM for isolated patterns, the size of which is less than the wavelength of the ArF excimer laser. Finally, we predicted the resolution limit of optical lithography through the aerial image simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.113-115
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• 1994

We considered the ion and photo-induced properties as a function of wavelength by exposing the light over the band gap of a-Ag/a-$Se_{75}$$Ge_{25}$ and the low-energy defocused $Ga^{+}$ ion beam on Ag/a-$Se_{75}$$Ge_{25}$ thin film. This film acts as a negative resist for photo or ion beam lithography. We observed that the absorbance coefficient decreased with increasing the photo-exposing time and exposing the ion beam. The bandgap shifts toward longer wavelength called a "darkening effect" are observed in the films exposed to both photons and ions. We suggest that a primary step in the Ag layer and a secondary step is in a-$Se_{75}$$Ge_{25}$ film layer.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.1-5
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• 2022

In this paper, the photocurrent characteristics of gate/body-tied (GBT) metal-oxide semiconductor field-effect transistor (MOSFET)-type photodetector with high sensitivity in the 408 nm - 941 nm range are presented. High sensitivity is important for photodetectors, which are used in several scientific and industrial applications. Owing to its inherent amplifying characteristics, the GBT MOSFET-type photodetector exhibits high sensitivity. The presented GBT MOSFET-type photodetector was designed and fabricated via a standard 0.18 ㎛ complementary metal-oxide-semiconductor (CMOS) process, and its characteristics were analyzed. The photodetector was analyzed with respect to its width to length (W/L) ratio, bias voltage, and incident-light wavelength. It was confirmed experimentally that the presented GBT MOSFET-type photodetector has over 100 times higher sensitivity than a PN-junction photodiode with the same area in the 408 nm - 941 nm range.

• Journal of Magnetics
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• v.11 no.4
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• pp.195-207
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• 2006

The recently published and new results on design and fabrication of magnetophotonic crystals of different dimensionality are surveyed. Coupling of polarized light to 3D photonic crystals based on synthetic opals was studied in the case of low dielectric contrast. Transmissivity of opals was demonstrated to strongly depend on the propagation direction of light and its polarization. It was shown that in a vicinity of the frequency of a single Bragg resonance in a 3D photonic crystal the incident linearly polarized light excites inside the crystal the TE- and TM-eigen modes which passing through the crystal is influenced by Brags diffraction of electromagnetic field from different (hkl) sets of crystallographic planes. We also measured the faraday effect of opals immersed in a magneto-optically active liquid. It was shown that the behavior of the faraday rotation spectrum of the system of the opal sample and magneto-optically active liquid directly interrelates with transmittance anisotropy of the opal sample. The photonic band structure, transmittance and Faraday rotation of the light in three-dimensional magnetophotonic crystals of simple cubic and face centered cubic lattices formed from magneto-optically active spheres where studied by the layer Korringa-Kohn-Rostoker method. We found that a photonic band structure is most significantly altered by the magneto-optical activity of spheres for the high-symmetry directions where the degeneracies between TE and TM polarized modes for the corresponding non-magnetic photonic crystals exist. The significant enhancement of the Faraday rotation appears for these directions in the proximity of the band edges, because of the slowing down of the light. New approaches for one-dimensional magnetophotonic crystals fabrication optimized for the magneto-optical Faraday effect enhancement are proposed and realized. One-dimensional magnetophotonic crystals utilizing the second and the third photonic band gaps optimized for the Faraday effect enhancement have been successfully fabricated. Additionally, magnetophotonic crystals consist of a stack of ferrimagnetic Bi-substituted yttrium-iron garnet layers alternated with dielectric silicon oxide layers of the same optical thickness. High refractive index difference provides the strong spatial localization of the electromagnetic field with the wavelength corresponding to the long-wavelength edge of the photonic band gap.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.7
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• pp.1044-1049
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• 2014

This study was conducted in order to investigate whether the presence of light or different colors of light would influence the energy expenditure and behavior of broiler chickens. Eight 8-week-old broiler chickens were adapted to a respiration chamber (Length, 28.5 cm; Height, 38.5 cm; Width, 44.0 cm) for one week prior to the initiation of the experiment. In experiment 1, energy expenditure and behavior of the chickens were analyzed in the presence or absence of light for four days. Chickens were exposed to 6 cycles of 2 h light/2 h dark period per day. In experiment 2, the broiler chickens that had been used in experiment 1 were used to evaluate the effect of 4 different wavelength light-emitting diodes (LEDs) on the energy expenditure and behavior of broiler chickens. The LEDs used in this study had the following wavelength bands; white (control), red (618 to 635 nm), green (515 to 530 nm) and blue (450 to 470 nm). The chickens were randomly exposed to a 2-h LED light in a random and sequential order per day for 3 days. Oxygen consumption and carbon dioxide production of the chickens were recorded using an open-circuit calorimeter system, and energy expenditure was calculated based on the collected data. The behavior of the chickens was analyzed based on following categories i.e., resting, standing, and pecking, and closed-circuit television was used to record these behavioral postures. The analysis of data from experiment 1 showed that the energy expenditure was higher (p<0.001) in chickens under light condition compared with those under dark condition. The chickens spent more time with pecking during a light period, but they frequently exhibited resting during a dark period. Experiment 2 showed that there was no significant difference in terms of energy expenditure and behavior based on the color of light (white, red, green, and blue) to which the chickens were exposed. In conclusion, the energy expenditure and behavior of broiler chickens were found to be strongly affected by the presence of light. On the other hand, there was no discernible difference in their energy expenditure and behavior of broiler chickens exposed to the different LED lights.