• Current Optics and Photonics
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• v.1 no.2
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• pp.157-162
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• 2017

In large liquid crystal displays, the image quality in an oblique viewing direction is a crucial issue. From this perspective, 8-domain polymer-stabilized vertical alignment (PS-VA) mode has been developed to suppress the color shift in oblique viewing directions, compared to that in 4-domain PS-VA mode. To realize the 8-domain PS-VA, the four domains in a pixel are each divided into two regions, such that applying different electric potentials result in different tilt angles in these two regions, while keeping four azimuthal directions in each domain. However, applying different voltages in a pixel causes drawbacks, such as requiring additional processes to construct a capacitor and a transistor, which will further reduce the aperture ratio. Here we propose a different approach to form the 8-domain, by controlling surface polar anchoring energy and the width of patterned electrodes in two regions of a pixel. As a result, the gamma-distortion index (GDI), measured at an azimuthal angle of $0^{\circ}$, is reduced by about 23% and 8%, compared to that of a conventional 4-domain at polar angles of $30^{\circ}$ and $60^{\circ}$ respectively.

• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.757-764
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• 2013

A panoramic video which supports to make viewers feel an immersion through fitting to a wide field of view (FOV) larger than the human visual angle needs an interactive viewing method such as selecting targeted view point among widely viewing points of a panoramic video because it difficult to simultaneously view a whole panoramic video due to a limited viewing environment and bandwidth. When a user officially uses a view navigation in order to select a view point, it happens waste of resources such as bandwidth owing to the transmitted video data of unnecessary view points. Therefore, this paper proposes the spatial-temporal prediction filter (STPF) which is based on the direction and velocity of the view navigation for transmitting only the necessary video data. As a result of simulation, STPF reduces bitrate saving rates by from 6% to 37% compared to conventional methods in the interactive panoramic video streaming service required high bandwidth.

• Journal of the Optical Society of Korea
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• v.5 no.2
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• pp.55-59
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• 2001

Results of an experimental study of possible ways to extend the capabilities of a big size transmission type holographic screen are presented. Different approaches to the problem of making a big size screen have been considered and tested experimentally. Up to 60$\times$80 $\textrm{cm}^2$ screens have been recorded on a single photographic plate VRP-M. By attaching a mirror behind the screen, the reflection mode of operation has been obtained. In this arrangement some additional peculiarities appear in the screen, which can be used to extend the screen capabilities. The first possibility is to increase the screen size by mosaicking the subscreens in the reflection mode of operation. Screens of 120$\times$80 $\textrm{cm}^2$ and 180$\times$40 $\textrm{cm}^2$ have been obtained by proper alignment of 60$\times$40 $\textrm{cm}^2$ subscreens. The second possibility is to move the viewing Bone by rotation of the screen together with the mirror and thereby realize by the eye-tracking capability. Methods of increasing vertical size of the viewing zone have been considered. Along with the multi-exposure method, which was considered in previous papers, addition of the vertical diffuser with the optimized scattering angle has been tested experimentally. The vertical size of the viewing zone has been increased by up to 10-15 cm. Another method consists of usage of a diffraction grating with vertical dispersion to solve the same problem.

• Proceedings of the KSRS Conference
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• v.2
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• pp.651-654
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• 2006

Infrared channels of newly launched Japanese geostationary satellite, MTSAT-1R are compared with well calibrated MODIS/Terra infrared measurements at 3.7, 6.7, 11, 12 ${\mu}m$ bands. There are four steps in this intercalibration method: 1) data collection, 2) spectral response function correction, 3) data collocation, and 4) calculation of mean bias and conversion coefficients. In order to minimize the navigation error of MTSAT-1R, comparisons are made over the area in which the viewing angle of MTSAT-1R is less than 50$^{\circ}$. The calibration method was tested for August 2005 and within the 40$^{\circ}N$-40$^{\circ}S$, 100$^{\circ}$E-180$^{\circ}$E domain. The differences of spectral response functions were corrected through radiative transfer model simulation. Constructing collocated data differences in viewing geometry, observation time and space were taken into account. In order to avoid the radiance variation induced by cloud presence, clear-sky targets are selected as intercalibration target. The mean biases of 11, 12, 6.7, and 3.7 ${\mu}m$ bands are about -0.16, 0.36, 1.31, and -6.69 K, suggesting that accuracies of 3.7 ${\mu}m$ is questionable while other channels are comparable to MODIS

• Journal of the Korean Society of Visualization
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• v.14 no.2
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• pp.18-24
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• 2016

This paper presents an experimental investigation to visualize cross-sectional two-phase flow structure and identify liquid-gas interface for condensation of steam at a low mass flux in a slightly inclined tube using the axial-viewing technique, which permits to look directly into flow during condensation of steam. In this technique, two-phase flow is viewed along the axis of a pipe by locating a high-speed video camera in front of a viewer that is fitted at the outlet of the pipe. A short section of the pipe is illuminated and is recorded through the viewer, which is kept free of liquid by mildly introducing air. Experiments were conducted in a pipe of 19.05 mm in inner diameter at atmospheric pressure. Cross-sectional two-phase flow structure is obtained at a steam mass flux of $2.62kg/m^2s$ as a function of steam quality in the range from 0.5 to 0.9. The results show that stratified-wavy flow is a unique flow pattern observed in the scope of the present study. Condensate film thickness, stratification angle and void fraction were measured from the obtained flow structure images. Finally, heat transfer coefficient was calculated using the measurement data and discussed in comparison with existing correlations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.494-498
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• 2016

In this paper, we proposed the 3-dimenstional (3D) analysis for calculating the optical characteristics of an autostereoscopic display with electric field driven liquid crystal (ELC) lens. From 3D analysis considering the slanting of lens, we calculate the cross-talk of each images and the distortion of viewing zone. Using geometric opics and extended Jones matrix method (EJMM), phase retardation of ELC lens according to position is calcuated and then optical path difference in 3D space considering tilt and azimuth angle of incident light is gotten. Then, intensity distribution is presented in the space. Through camparing the intensity distribution using ideal lens with the ELC lens, we identify the noise and image distortion of ELC lens. As a result, this analysis is expected to provide optimum design conditions for realistic and rigorous 3D display with ELC lens.

• Journal of Information Display
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• v.5 no.2
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• pp.23-26
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• 2004

For high end, large area displays, all current LC modes require some degree of optical compensation to improve the front of screen viewing experience. Currently most optical films are laminated to the outside of the LCD cell, between the glass and polariser. In this paper we wish to show how it is possible to integrate the compensating optical film within a VA mode LCD cell. The paper will describe the process of making the biaxial film through the process of in-situ photopolymerisation of an aligned film of reactive mesogens in the cholesteric phase using polarised UV light. The film can be made on the colour filter array side of the LCD panel. In addition the process of fabricating a VA mode LCD containing this film will be described and the performance of this module will be presented.

• Journal of the Korean housing association
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• v.20 no.5
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• pp.9-21
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• 2009

This study classified visual perception types of access space at 17 five-star hotels in Jejudo and examined their cognitive characteristics and image formation structures in an effort to provide basic information important for designing the elevation and the access spaces of a hotel. The results of this study are as follows. Access space image of experimental hotels showed more negative evaluations at both city hotels and resort hotels, viewing angle (upward angle) was also positively evaluated between $10^{\circ}{\sim}12^{\circ}$ and $18^{\circ}$ and central type in arrangement type and detour access and straight access types in access circulation type were positively evaluated. When viewed from an upward angle of $10^{\circ}$ to $12^{\circ}$, the most important factors were as plasticity, decorativeness, and creativity; from $18^{\circ}$ it was such factors as harmony and peculiarity; and at $45^{\circ}$ it was factors like decorativeness and stability. In considering the various access types, the most important factors in a straight access type were peculiarity and harmony; for one-time curved access type it was by decorativeness, creativity, Peculiarity, and stability; and for detour access types it was decorativeness, stability, and peculiarity. Influential of factors affecting image formation and plasticity and harmony factors and the form had more influences on image formation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.172-172
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• 2010

The Patterned vertical alignment (PVA) mode has many advantages such as perfect dark state at the normal direction and wide viewing angle. However, PVA mode needs additional process to pattern electrodes of both substrates and complicated assembly process. Moreover, this mode shows slow response time. To overcome these problems, we use plane shape ITO on top substrate instead of patterned electrode and form proper tilt angle of LC director on the surface while maintaining these original merits. Consequently, we achieve fast response time and improve transmittance.

• Journal of the Ergonomics Society of Korea
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• v.28 no.4
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• pp.71-76
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• 2009

Effects of dark adaptation have large safety implications. This study was aimed to investigate the effects of varying illuminance and the size of critical detail on visual performance (i.e., time-to-detect) in a dark room environment. While adapting to the dark environment, ten subjects were asked to detect and answer simple numerical expressions under 9 experimental conditions (3 illuminance level $\times$ 3 target size). The ANOVA results revealed that the time-to-detect was significantly affected by both of the illumination level and the size of critical detail. As illumination increased from 10 lux to 20 lux, the time-to-detect was significantly declined. For the size of critical detail, 0.5/min size (i.e., equal to 2 minutes of visual angle) resulted in a shorter time-to-detect, as compared to 0.7/min size (i.e., equal to 1.6 minutes of visual angle). Potential applications of this research include the development of design guidelines for illumination and warning signs in poorly illuminated viewing environments.