• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.490-491
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• 2007

We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum$(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric polarization of organic light emitting diodes using impedance. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of 40Hz to $10^8Hz$. We obtained dielectric constant and loss tangent (tan ${\delta}$) of the device. From these analyses, we are able to interpret a dielectric dispersion and dielectric absorption contributed by an interfacial and orientational polarization.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.3
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• pp.166-173
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• 2001

Hysteresis loops of the ferroelectric thin films such as PLZT(10/30/70), PLT(10) and PZT(30/70) was simulated using the field-dependent polarization model and compared to the measured loops. In case of PZT(30/70) thin film, as the real saturation or polarization at the applied voltage or larger than 5V appears slack and its value is quite different from the simulated one, it is deduced that the ferroelectric polarization of PZT(30/70) is generated not only by the pure dipoles but also by various electric charges. The drain current of quasi-MFISFET is expressed by using the square-law FET and field-dependent polarization models. The modeling results are analogous to the experimental values. The channel of quasi-MFISFET using PZT(30/70) forms more quickly compared to that of quasi-MFISFET using PLZT(10/30/70) or PLT(10) in the state of 'write' gate voltage of -10V. This may be because the decrease rate of the polarization in the PZT(30/70) thin film is 3~4 times more rapid than that of the polarization in the PLZT(10/30/70) or the PLT(10) thin film in the retention characteristics.

• Journal of IKEEE
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• v.27 no.4
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• pp.512-517
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• 2023

In this study, we propose a liquid crystal-based polarization control technology that can control polarization by adjusting the voltage applied to the liquid crystal, and apply it to a Closed-circuit Television (CCTV) to transmit only the desired angle of polarized light. CCTV with conventional polarizing films cannot control polarization because they focus on backlight compensation, so light reflected from the water surface or highlights reflected from vehicles interfere with subject identification. However, the Vertical Alignment mode allows the polarization to be adjusted electrically, so that only the polarized light at the user's desired angle is transmitted, eliminating reflected highlights. The images obtained using this technique are optimized by computer software. Liquid crystal polarization panels, which can electrically control the polarization angle, transmittance, and polarization rate, have been applied to polarized image monitoring device to improve subject identification in conventional CCTV.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1206-1212
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• 2018

In this study, the polarization reversal characteristics of thin film capacitors with a thickness of 100 nm or less fabricated with ferroelectric polymer were measured and analyzed. For the fixed film thickness, polarization reversal occurred at higher coercive fields as the applied maximum electric field increased. For the fixed maximum electric field, polarization reversal occurred at the same coercive field irrespective of the thickness of the thin film. The proportional constant values between the logarithmic electric field and the logarithmic scale frequency were $0.12{\pm}0.01$ for all measurements. As a result, the ferroelectric polymer capacitors consistently exhibited polarization reversal characteristics without any size effects up to a thickness of 40 nm. This study shows the possibility of a polymer memory device that can operate at low voltage, which is useful for predicting the behavior of a low-voltage operating polymer memory device.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.25-32
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• 2021

In this paper, the Magneto-Electric(ME) dipole array antenna with dual-polarization in the X-Band is proposed and it is implemented and measured. The proposed array antenna is composed of 32 single ME dipole antenna and a Teflon PCB. 1 × 1 ME dipole antenna is implemented dual-polarization by radiating vertical polarization and horizontal polarization from two pairs of radiators. 2-port feeding structures are realized by lamination process using LTCC. And, each port independently feeds the radiator through a Γ-shaped feeding strip with isolation between ports. The Teflon PCB used in the antenna array has a 4-layer structure, and 2-port is fed through the top and bottom layers. The λ_g/4 transformer is applied to the transmission line of the Teflon PCB for impedance matching of the arrayed antenna and the Teflon PCB, and the optimal parameters are obtained through simulation. The measured maximum antenna gains of port 1 was 18.2 dBi, Cross-pol was 1.0 dBi. And the measured maximum antenna gains of port 1 was 18.1 dBi, Cross-pol was 3.2 dBi.

• Journal of the Optical Society of Korea
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• v.7 no.4
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• pp.234-239
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• 2003

Objective methods to assess quantitatively port wine stain (PWS) blanching in response to laser therapy are needed to improve laser therapeutic outcome. Previous studies have attempted to assess objectively PWS color based on point measurement devices. To date, these approaches have typically been limited by a number of factors such as small test area and need for contact. To address these issues, a polarization spectral imaging system and an image analysis method have been developed to evaluate quantitatively erythema and melanin content distribution in skin. The developed polarization spectral imaging system minimizes artifacts such as glaring, shadowing, and non-uniform illumination that interfere with image fidelity. Furthermore, the image analysis method has been employed to get images of skin melanin and erythema indices from the acquired color images for quantitative analysis. Finally, using PWS patient color image, the effectiveness in laser treatment of PWS was evaluated by calculating relative erythema index image that is the relative erythema index of PWS region to the normal region. The developed device and analysis method appears to be a simple and effective method for quantitative analysis of PWS blanching.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.134-139
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• 2002

We report an experimental investigation of the wavelength and polarization selectivity of a side-polished fiber in contact with a metal-clad planar waveguide. The influences of the structural parameters of the planar waveguide, including refractive index of the superstrate and metal thickness, on the optical transmission characteristics of the device were measured and explained. The conditions for high wavelength and polarization selectivity wore predicted and demonstrated experimentally.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.326-329
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• 1999

In this paper, we demonstrate a polarization independent optical phase modulator using electro-optic polymer, P2ANS. To overcome the intrinsic polarization dependency of electro-optic effect, we control the optic axis using a new electrode structure. P2ANS(42:75) and P2ANS(25:75) are used for the core layer and the cladding layer, respectively. The buried-type single mode waveguide is fabricated by oxygen ion reactive etching and electic poling is performed by applying 1, 200V at 135$^{\circ}C$. The measured V$_{\pi}$ of the device for both TE and TM modes are 70V.

• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.214-223
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• 2013

This paper proposes a theoretical analysis of hidden device detection and a design of multiband circular polarization patch array antenna for non-linear junction detector system application. A good axial ratio of circular polarization patch antenna is realized by a new approach that employs inclined slots, two rectangular grooves and a truncated ground for the conventional antenna. A good axial ratio of the 1.5 dB lower is measured by having an asymmetric gap distance between the ground planes of the coplanar waveguide feeding structure. The common ground plane of the linear array has an optimum trapezoidal slot array to reduce the mutual coupling without increasing the distance between the radiators. The higher gain of about 1 dBi is realized by using the novel common ground structure. The measured return loss, gain, and axial ratio of the proposed single radiator, as well as the proposed array antennas, showed a good agreement with the simulated results.

• Journal of the Optical Society of Korea
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• v.6 no.3
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• pp.117-120
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• 2002

Side-polished single-mode fiber covered with a thick planar-glass-waveguide is studied as a polarization-insensitive fiber-optic refractometer The properties of the device are very sensitive to the index variation of an upper cladding on top of the overlay waveguide. We investigate the spectral response, the polarization properties, and the relationship between the shift in coupling wavelength and the index variation of an upper cladding layer Index resolutions of the order of 10-4 have been achieved.