• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.1077-1079
• /
• 2008

Nanoparticles-induced vertical alignment (NIVA) in the liquid crystal (LC) devices was observed and has been applied successfully on fabricating the hybrid-aligned nematic LC cells and guest-host LC cells. In this talk, we will discuss the characteristics of the electric and optical properties of NIVA-LC cells with different dopant concentrations and demonstrate that nanoparticles can be spin-coated on the substrate at a low temperature.

• Journal of Institute of Control, Robotics and Systems
• /
• v.5 no.7
• /
• pp.787-793
• /
• 1999

A self-sensing magnetic suspension system utilizing a LC resonant circuit is proposed by using the characteristic that the inductance of the magnetic system is varied with respect to the air gap displacement. An external capacitor is added into the electric system to make the levitation system be statically stable system, which much relieves the control effort required to stabilize the magnetic suspension system of haying an intrinsic unstable nature. For the realization of the self- sensing magnetically levitated system, an amplitude modulation / demodulation method is used with a positive position feedback controller Experimental results are presented to validate the proposed method.

• Proceedings of the KIEE Conference
• /
• 2002.06a
• /
• pp.153-157
• /
• 2002

Electricity living body formation operation appliance is using most imports until present. And, because electricity living body formation operation appliance is too expensive, it becomes burden to buy in small scale hospital. Also, problem that economical damage by income is added follows, Therefore, this treatise developed electricity living body formation operation appliance by home production, Ultra high frequency eruption circuit used LC circuit, and output frequency is possible to 8 [MHz], and output voltage amplified maximum 800 [V]. This operation appliance could display size of fixed current. This developed product could microscopic operation fewer than 1 [mm]. This development technology is considered by do metallic surface heat treatment, melting, welding, induction heating device and that can apply to domestic animals surgical operation and so on.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.11
• /
• pp.2860-2870
• /
• 1994

When crack are detected in aged turbine rotors of power plants, information on fracture resistance of the aged material at operating temperature is needed for determination of critical loading condition and residual life of the turbine. In this study, fracture toughness (J$_lc$) and tearing modulus(T$_mat$) of virgin and thermally degraded 1Cr-1Mo-0.25V steel, which is one of the most widely used rotor steels, were measured at 538.deg. C according to ASTM E813 and ASTM E1152, respectively. Five kinds of specimen with different degradation levels were prepared by isothermal aging heat treatment at $630^{\circ}C.$ It was observed that J$_lc$ and T$_mat$ value decreased as the degradation level increased. Analysis of microstructures using a scanning electron microscope showed that the decrement of J$_lc$ is related to segregation of impurities at grain boundaries. It was also verified that the DC electric potential drop method is accurate and reliable for crack length monitoring at elevated temperature.

• Journal of the Korean Applied Science and Technology
• /
• v.13 no.2
• /
• pp.29-37
• /
• 1996

The phase separated structure and the electo-optical properties of the polymer /liquid crystal(LC) composite films including a dye were investigated. The phase separated structure of the polymer /LC / dye composite film(GH composite film) including below 2wt% dye against LC was almost same with the composite film which does not include dye. But the electro-optical properties of the GH composite film strongly depended on weight fraction of the dye against the LC. The response time of the GH composite film increased with the increase of the dissolved dye in LC because the dye acts as a registivity for the orientation of LC molecules by the electric filed.

• Journal of the Korean Applied Science and Technology
• /
• v.12 no.2
• /
• pp.29-39
• /
• 1995

The phase separated structure and the electro-optical properties of the (polymer/liquid) crystal : LC) composite film strongly depended on the weight fraction of LC in it. The continuous LC phase was formed in a three-dimensional polymer network when the LC weight fraction was above 40wt%. The aggregation structure of the composite film could be controlled by controlling the solvent evaporation velocity during the film preparation process. The smaller LC domains or channels were formed in the case of the faster solvent evaporation velocity. The composite film exhibited reversible light scattering-light transmission switching upon electric field -OFF and -ON states, respectiverly. The light scattering properties of the composite film strongly depended on the spatial distortion of the nematic directors as well as the mismatch in refractive indices between matrix polymer and LC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.4
• /
• pp.241-245
• /
• 2017

This paper proposes a private display that can adjust viewing angles by using an electric-field-driven (EFD) LC Lens. The EFD LC Lens design and simulation were analyzed by using the Extended Jones Matrix Method. The conventional method for attaching a private film to the display was difficult. In order to solve this problem, in this study, by using the EFD LC Lens, we devised a method that can view images more conveniently. We analyzed the luminance and illumination of the optical viewing distance by using the Extended Jones Matrix Method. We also measured the intensity of the viewing angles. The simulation attached the EFD LC Lens to the 14" Full HD RGB stripe wide panel. We calculated the relative luminance distribution and the luminance distribution on the viewing angle of the image at the optimum viewing distance of 60 cm, using the EFD LC Lens and the lenticular lens. The proposed method could be used to design private displays that can adjust the viewing angle of the EFD LC Lens.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.4
• /
• pp.951-960
• /
• 2016

Tower insulators in electric power transmission network play a crucial role in preserving the reliability of the system. Electrical utilities frequently face the problem of flashover of insulators due to pollution deposition on their surface. Several research works based on leakage current (LC) measurement has been already carried out in developing diagnostic techniques for these insulators. Since the LC signal is highly intermittent in nature, estimation of pollution severity based on LC signal measurement over a short period of time will not produce accurate results. Reports on the measurement and analysis of LC signals over a long period of time is scanty. This paper attempts to use Random Forest (RF) classifier, which produces accurate results on large data bases, to analyze the pollution severity of high voltage tower insulators. Leakage current characteristics over a long period of time were measured in the laboratory on porcelain insulator. Pollution experiments were conducted at 11 kV AC voltage. Time domain analysis and wavelet transform technique were used to extract both basic features and histogram features of the LC signal. RF model was trained and tested with a variety of LC signals measured over a lengthy period of time and it is noticed that the proposed RF model based pollution severity classifier is efficient and will be helpful to electrical utilities for real time implementation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.34 no.5
• /
• pp.321-326
• /
• 2021

We fabricated BiAlO thin film by a solution process with a brush coating to be used as liquid crystal (LC) alignment layer. Solution-processed BiAlO was coated on the glass substrate by brush process. Prepared thin films were annealed at different temperatures of 80℃, 180℃, and 280℃. To verify whether the BiAlO film was formed properly, X-ray photoelectron spectroscopy analysis was performed on Bi and Al. Using a crystal rotation method by polarized optical microscopy, LC alignment state was evaluated. At the annealing temperature of 280℃, the uniform homogenous LC alignment was achieved. To reveal the mechanism of LC alignment by brush coating, field emission scanning electron microscope was used. Through this analysis, spin-coated and brush coated film surface were compared. It was revealed that physical anisotropy was induced by brush coating at a high annealing temperature. Particles were aligned in one direction along which brush coating was made, resulting in a physical anisotropy that affects a uniform LC alignment. Therefore, it was confirmed that brush coating combined with BiAlO thin film annealed at high temperature has a significant potential for LC alignment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1054-1057
• /
• 2003

We have studied $90^{\circ}$ twisted nematic (TN) mode driven by fringe electric field, where two polarizers are parallel each other such that the cell shows a black state before a voltage is applied. According to the studies by computer simulation for a LC with negative dielectric anisotropy, the LC twists perpendicular to the horizontal field direction of fringe electric field and the degree of tilt angle is very low, when a voltage is applied. Therefore, the new device exhibits wide viewing angle characteristic due to in-plane switching and high transmittance since the LC director aligns parallel to the polarizer axis.