• Journal of the Optical Society of Korea
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• v.13 no.2
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• pp.256-260
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• 2009

The optical performance of the reflective polarizer was investigated over three kinds of direct-lit backlights and/or different configurations of the optical sheets. The optical gain factor achieved by using the reflective polarizer increased as the diffuse nature of the optical sheet was enhanced, because of the more efficient polarization conversion. In addition, the gain factor decreased substantially in flat-lamp backlights compared to tubular-lamp backlights, which was ascribed to the high loss factor during the polarization recycling process due to the complex structure and large area of flat lamps. All these results suggested that reducing the loss factor of the backlight is very important for efficient polarization conversion and thus high optical gain of the reflective polarizer.

• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.170-175
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• 2010

This article proposed polarization selective antenna for UHF RFID system. The proposed antenna is consist of microstrip patch antenna with dual feeding and two SPDT switches and a SP4T switch and 3dB hybrid coupler. Through control of voltage of switches, the proposed reader antenna can select horizontally linear polarization, vertically linear polarization, left-hand circular polarization (LHCP) and right hand circular polarization (RHCP). The proposed reader antenna satisfied 2:1 VSWR at 902MHz ~ 928MHz. and 3dB under AR(axial ratio). And it can select appropriative polarization with user environment and tag polarization. So it minimize PLF and increased reading distance.

• Journal of Information Display
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• v.10 no.1
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• pp.28-32
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• 2009

The correlation between the optical performance of the reflective polarizer, which is a key optical component for the brightness enhancement of the liquid crystal display (LCD), and the configuration of optical sheets was investigated in a direct-lit CCFL (cold-cathode fluorescent lamp) backlight. The optical gain of the reflective polarizer, the polarization state of the light emitted from each film, and the loss factor for the polarization conversion process occurring in the lower part of the backlight were determined using a phenomenological approach for the polarization recycling process. The present study suggests that the correlation between the optical performance of the brightness enhancement films and the backlight configuration should be carefully considered in the optimization of the backlight structure.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.2
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• pp.72-78
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• 2021

This paper proposes a wide-band dual-polarization stacked patch array antenna for satellite SAR system applications. The array antenna was designed for loss minimization and wide-band characteristics to enhance the performance of the SAR system and optimize it for active return loss in applications to active phased arrays. The fabricated array antenna showed a performance of 19.26%/19.79% fractional bandwidth within the -10 dB reference level of the active return loss and showed loss characteristics of 0.797 dB/0.799 dB averaged within the operational frequency for both H/V-polarization cases. The pattern performance was verified by comparing the measured patterns with the calculated patterns obtained by the array factor.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.425-426
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• 2008

The Panda-type polarization maintaining fibers were fabricated by VAD(vapor-phase axial deposition) method. We fabricate Panda style polarization maintaining fibers that have small form factor($80{\mu}m$), high H-parameter of about $1{\times}10^{-4}/m$ and low optical loss of about 3dB/km.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.107-112
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• 2013

In this paper, we discuss a 3-dimensional localization sensor node using EM waves (Electromagnetic waves) with RSSI (Received Signal Strength Indicator). Generally EM waves cannot be used in underwater environment, because the signal is highly attenuated by the water medium according to the distance. Although the signal quickly reduces in underwater, the reducing tendency is very clear and uniform. Hence EM waves have possibility as underwater distance sensors. The authors have verified the possibility by theory and several experiments, and developed calibration methods in case of linear and planer environment. For 3-dimensional localization in underwater, it must be known antenna's radiation pattern property in electric plane(called E-plane). In this paper, we proceed experiments to verify attenuation tendency with z axis movement, PLF (Polarization Loss Factor) and ILF (Inclination Loss Factor) with its theoretical approach.

• Journal of Ocean Engineering and Technology
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• v.17 no.3 s.52
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• pp.39-45
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• 2003

Shot peening is an effective method of improving the fatigue strength of components and structures. The compressive residual stress produced by surface plastic deformation with shot peening is usually regarded as the major factor in increasing fatigue strength. In this study, the influence of shot peening on corrosion was investigated. Spring steel immersed in $3.5\%$ NaCl prior was used to evaluate the effect of shot peening on fatigue properties. The immersion test was performed on the five kinds of specimens with shot peened and unpeened. The distributions of residual stresses of shot peened spring steels were measured in an X-ray diffraction apparatus, using the two-point method. Corrosion potential, polarization curve, residual stress, etc. were investigated, based on the experimental results. From test results, the effect of shot peening on the corrosion was evaluated.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.151-156
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• 2012

Reflective polarizers can be used as luminance enhancement films for LCD backlights via the polarization recycling process. The optical performances of a wire grid polarizer (WGP) as a reflective polarizer adopted in edge-lit backlights were investigated by luminance evaluation and a time-domain simulation technique. The results were compared to those of a commercial dielectric multilayer film. The luminance gain factor of WGP was smaller than that of the multilayer film by 18%. This was attributed to a much larger internal loss of WGP due to light absorption by metal wires. The internal losses of both reflective polarizers and the polarization conversion efficiency of the backlight were obtained numerically based on a phenomenological model. The optical performances of WGP were optimized by using a time-domain simulation technique. The luminance gain increased and was found to become comparable to, but slightly less than the case of the dielectric multilayer film with decreasing line width.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.665-668
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• 1999

Thin films of Pb(Zr,Ti)O$_3$ were fabricated by means of the sol-gel spin-coating method and the multi-coating of eight coating numbers. The thin films were dried on the temperature range of 250 ~ 400($^{\circ}C$), whenever the specimens were dried after each coating Processing. The fabricated ferroelectric thin films of lead zirconate titanate(PZT) were treated with the rapid thermal annealing(RTA) at 650($^{\circ}C$),or 3(min), and direct insertion thermal annealing(DITA) at 650($^{\circ}C$), for 30(min). The measured properties of dielectric thin films were following: The good results of dielectric properties were shown by the RTA specimen. The saturation polarization(Ps), remanent polarization(Pr), coercive field (Ec), dielectric constant and dielectric loss factor of the RTA specimen were estimated to be about 27.1[ $\mu$ C/$\textrm{cm}^2$], 13.7[ $\mu$ C/$\textrm{cm}^2$], 55.6(kV/cm), 786 and 6.4(%) respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.10a
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• pp.25-28
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• 2000

In this paper, the technology for accelerating degradation & life estimation on the traction motor was introduced with the stator form-winding sample coils of the 200 Class insulation system The accelerative degradation was performed in 10 cycles, which were composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, condition diagnosis test such as insulation resistance & polarization index, capacitance & dielectric loss and partial discharge properties were investigated in the temperature range of $20{\sim}160^{\circ}C$. Relationship between degradation conditions and diagnosis results were analyzed to find an dominative degradation factor at the end-life point