• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.146-151
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• 2001

The effects of slant interface in the hybrid specimen on the dynamic crack propagation behavior have been investigated using dynamic photoelasticity. The dynamic photoelasticity with the aid of Cranz-Shardin type high speed camera system is utilized to record the dynamic stress field around the dynamically propagating inclined interface crack tip in the three point bending specimens. The dynamic load is applied by a hammer dropped from 0.08m high without initial velocity. The dynamic crack propagation velocities and dynamic stresses field around the interface crack tips are investigated. Theoretical dynamic isochromatic fringe loops are compared with the experimental reults. It is interesting to note that the crack propagating velocity becomes comparable to the Rayleigh wave speed of the soft material of a specimen when slant angle decreases.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.4 no.4
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• pp.43-51
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• 1990

레이저 비임이 대기중을 전파할 때 고류(turbulence)의 영향을 고려해야 한다. 고류의 영향에 의한 프린지 시도는 extended Huygens-Fresnel principle을 도입하여 타원체로 간주할 수 있는 프린지 체적에서 장의 전 분포를 시하고 이 전 분포로부터 평균 강도분포를 얻었으며, 평균 강도분포를 구하기 위해 Fourier-Bessel적분을 행하였다. 평균 강도분포에서 최대 평균 강도분포max 및 최소 평균 강도분포 min을 얻었으며, 이 식들을 프린지 시도의 정의 식 V=(Imax-Imax)/(Imax+Imin)에 적용하였다. 본 논문에서는 광원으로 파장 =4880[]인 아르곤 레이저를 사용하였고 광원의 모우드는 TEM..모우드로 하였다. 또한 비임의 교각 =5˚, 광원으로부터 프린지 체적 까지의 거리 L=10[m], en 광원간의 거리 B=(2tan /2)L, 특성 비임 반경 =2 /[ ( /2)]을 이용하여 프린지 시도에 관한 결과를 얻었으며, 이 결과에 의하면 L'( / ·L)에 대한 변수 r의 비 r/L'= 에서 V=1이고, r/L=0.1에서 프린지 시도가 감소한다. 또 강 고 류인 경우와 약 고 류인 경우에 대해 프린지 시도를 비교하였을 때 강 고류에서 감소폭이 크다는 사실을 알 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.43-44
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• 2000

The fringe-field switching (FFS) display is known to exhibit wide-viewing-angle and high transmittance. We have simulated pretilt effects on electro-optic characteristic of the device when a liquid crystal with positive and negative dielectric anisotropy is used. The results show that asymmetry in contour of luminance and light leakage in the dark state are increased but voltage-dependent transmittance curves remain about the same, as the pretilt angle increases to $10^{\circ}$.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.426-429
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• 2005

The fringe-field switching (FFS) mode associated with a transition from a homogenously aligned to twist deformation require rubbing process. In this devices, $1^o$ of misalignment in an azimuthal direction could cause voltage-dependent transmittance (V-T) to be different from that in a normal area and consequently results in a rubbing mura. According to our studies, the single domain FFS cells are much more sensitive to the rubbing mura than the dual domain FFS cell. Moreover, the FFS cells with negative LC are much more sensitive to the rubbing mura than the FFS cells with positive LC.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.419-422
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• 2005

We have studied transflective liquid crystal displays (LCDs) associated with fringe-field switching (FFS) mode to achieve high image quality. In the past, several cell structures were used to fabricate transflective FFS liquid crystal display s. Their structures and characteristics are carefully examined to find their merits and cons. Further, optimization of cell parameters to achieve a single driving circuit is performed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1028-1032
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• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also, the former method shows higher transmittance than that of the latter.

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.10-15
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• 2011

In this paper, we propose an auto-focusing algorithm which extracts a depth parameter by analyzing a selected part of a hologram, and we use experimental results to show that the algorithm is practical. First, we record a complex hologram using Optical Scanning Holography. Next we select some part of hologram and extract depth information through Gaussian low pass filtering, synthesizing a real-only hologram, power fringe-adjusted filtering and inverting to a new frequency axis. Finally, we reconstruct the hologram automatically using the extracted depth location.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.545-548
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• 2007

This Viewing angle control of fringe-field switching (FFS)-LCD using only one panel has been investigated. Viewing angle switching cell is composed of main- and sub-pixel, in which the former has a role of image expression and the latter has a role of viewing angle switching.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.527-530
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• 2007

Film compensation to suppress a light leakage in the dark state of fringe-field switching (FFS) at off normal direction was performed by optimizing retardation value of discotic (negative A) and TAC films including in-plane switching (IPS). The normal FFS mode shows wide viewing angle characteristics that region of CR 10:1 is over $70^{\circ}$ of polar angle in all directions. The optimized FFS cell exhibits much better performances than other methods do in terms of CR and color uniformity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.12
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• pp.1068-1071
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• 2007

When a dielectric layer, in-cell retarder (ICR) is formed between electrode and LC layer to get a single gap transflective fringe-field switching (FFS) display, the operating voltage ($V_{op}$) is highly increased due to the thickness of dielectric material. But, we also knew the phenomenon that the increasing rate of Vop is different whether the 1st common electrode was composed of plate type or slit type. In this paper, the common electrode in transmissive part was composed of slit type which had less steepness effect of the Vop and in reflective part was composed of plate type. The rubbing angle of reflective part can be adjusted properly to match the voltage dependent transmittance and reflectance.