• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.87-93
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• 2014

Optical brightening agents (OBA) is generally used to improve the optical property of printing paper in the paper industry. However, effects of OBA addition on paper preservability has been not fully understood yet. Therefore, this study was aimed to investigate effects of a OBA on the aging characteristics of paper. The OBA treatment of three different types was performed by dipping a filter paper into each a OBA solutions of different concentrations. The filter papers applied with a OBA were artificially aged at 80oC and 65% RH, and their optical and mechanical properties were evaluated. It was found that application of OBAs influenced the aging characteristics of paper. Especially, after aging, the optical and mechanical properties of the filter paper treated with the tetra-type OBA were more significantly decreased than those of the non-treated filter paper. The more the concentration of the tetra-type OBA increased, the more decreasing rate of optical and mechanical properties of the filter paper. While, in case of di-type OBA and hexa-type OBA, paper optical and mechanical properties were slightly decreased or not changed with a OBA treatment.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.494-499
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• 2013

In this paper, we present an optical encryption and information authentication of 3D objects considering wireless channel characteristics. Using the optical encryption such as double random phase encryption (DRPE) and 3D integral imaging, a 3D scene with encryption can be transmitted. However, the wireless channel causes the noise and fading effects of the 3D transmitted encryption data. When the 3D encrypted data is transmitted via wireless channel, the information may be lost or distorted because there are a lot of factors such as channel noise, propagation fading, and so on. Thus, using digital modulation and maximum likelihood (ML) detection, the noise and fading effects are mitigated, and the encrypted data is estimated well at the receiver. In addition, using computational volumetric reconstruction of integral imaging and advanced correlation filters, the noise effects may be remedied and 3D information may be authenticated. To prove our method, we carry out an optical experiment for sensing 3D information and simulation for optical encryption with DRPE and authentication with a nonlinear correlation filter. To the best of our knowledge, this is the first report on optical encryption and information authentication of 3D objects considering the wireless channel characteristics.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.61-66
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• 2010

A flat luminaire utilizing 32" flat fluorescent lamp was developed and its optical characteristics were compared with that of the troffer using three T8 regular fluorescent tubes. The optical characteristics of the 32" flat luminaire was similar to that of the troffer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.6
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• pp.480-486
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• 2006

The radiation characteristics of a high-luminance light-emitting diode (LED) light source were studied to evaluate its potential as an energy-saving light source for fishing lamps. The angle of the LED light source with 50% illuminance was $8-15^{\circ}$, and it had strong directional characteristics. The wavelengths at which the radiance and irradiance were maxima were 709, 613, 473, 501, 525, and 465 nm for red, orange, blue, peacock blue, green, and white light, respectively. The underwater transmission characteristics of the LED light source were superior in the order blue, white, peacock blue, and green in optical water type I: blue, peacock blue, white, and green in optical water type II; and blue, peacock blue, green, and white in optical water type III. Setting the underwater transmission characteristics of the LED light source in optical water type I at 100%, the transmission of water types II and III decreased to 67 and 17%, respectively. Based on the underwater transmission characteristics calculated in optical water types I-III, the blue and peacock blue LED light sources can be used as an energy-saving light source for fishing lamps.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.67-72
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• 2005

This study proposes a design methodology to determine the optimum configurations of the optical flying head (OFH) for near-field recording systems. Since the OFH requires stricter static and dynamic characteristics of slider air-bearings within an optical tilt tolerance over the entire recording band, an optimum design to keep the focusing and tracking ability stable is essential. The desired flying characteristics considered in this study are to minimize the variation in flying height between the SIL and the disk from a target value, satisfying the restriction of the minimum flying height, to keep the pitch and roll angles within an optical tilt tolerance, and to ensure a higher air-bearing stiffness. Simulation results demonstrate the effectiveness of the proposed design methodology by showing that the static and dynamic flying characteristics of the optimally designed OFH are enhanced in comparison with those of the initial. The gap between the SIL and the disk can be kept at less than 100 nm even if the optical tilt tolerance of the SIL is considered.

• Current Optics and Photonics
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• v.7 no.1
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• pp.28-32
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• 2023

Frequency characteristics of gain-saturated erbium-doped fiber amplifier (EDFA) are experimentally evaluated to mitigate the optical signal fluctuation induced by atmospheric turbulence in terrestrial freespace optical communication systems. Here, an acousto-optic modulator (AOM) is used to emulate optical signal fluctuations induced by atmospheric turbulence. The waveform which is generated in proportion to the refractive-index structural parameters is used to drive the AOM at various periodic frequencies. Thus, the dependence of the signal fluctuation suppression on the frequency is evaluated. The experiment is conducted using a periodic frequency sweep of the AOM driving voltage waveform and signal input power variation of the amplifier. It is observed that a low periodic frequency and high input signal power effectively suppress the optical signal fluctuation. This study evaluates the experimental results from the high-pass filter and gain-saturation characteristics of the EDFA.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.162-163
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• 1999

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.142-146
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• 2007

Nowadays, itis inevitable trend to use high Xe gas contents for increase luminous efficiency and luminance in plasma display panel. However, the increase of Xe gas contents causes the driving voltage, although the brightness is increase. In this paper, we study the characteristics of electro optical according to Xe gas contents and gas pressure. Electro-optical characteristics were investigated by the discharge voltage, luminance and luminous efficacy measurements, respectively. With some increasing Xe gas contents and pressure, the electro-optical properties increased. However, the characteristics of electro-optical begin to be saturated, when too high increased Xe gas contents and pressure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.63-64
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• 2006

Recently, researches for high-speed optical devices have been increased to provide mass data transmission and high-speed optical communication. Optical modulator in the transmission link is one of the crucial devices in total optical network system and it can affect a great effect to the whole transmission properties. In this paper, traveling wave electro-absorption modulator (TWEAM) is examined to ensure high efficiency in the RF range and wide bandwidth. In addition, the temperature-dependence electrical characteristics of TWEAM is investigated. Temperature dependent property variations were characterized using I-V and C-V measurement.

• ETRI Journal
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• v.34 no.6
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• pp.954-957
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• 2012

Titanium foils for use in photoelectrochemical devices are treated with a $HNO_3$-HF solution. After this treatment, the optical reflection characteristics of the Ti substrates are markedly increased in terms of not only reflectivity but also optimized wavelength. Furthermore, the "multiple beam interference" theory and optical analysis of surface morphologies clearly verify the origin of the optimized optical reflection properties.