• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.122-123
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• 2003

LCD(Liquid Crystal Display)는 얇고, 가벼우며 소비전력이 적기 때문에, 휴대성 및 이동성이 높아 소비량이 급속도로 증가하고 있다. 또한 90년도 이후 LCD에 대한 연구 개발이 집중되고 제조기술이 향상됨에 따라 제품의 가격이 떨어져서 LCD의 효용가치는 더욱 높아지고 있다. 하지만, 현재 주로 사용되고 있는 Nematic 액정의 경우에 화면 표시 속도가 느려, 원활한 동화상을 구현하기에는 잔상이 남는 단점이 있다. (중략)

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.575-577
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• 2003

Achiral swallow-tailed liquid crystals derived from 1,3-dialkoxy-2-propanol were prepared and their mesomorphic properties were investigated. 1,3-Dialkoxy-2-propyl swallow-tailed material showed antiferroelectric-like smectic C phase at lower temperature and in broader temperature range than the corresponding compounds with a branched alkyl group as a swallow-tail. They could serve as suitable host for antiferroelectric mixtures.

• Bulletin of the Korean Chemical Society
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• v.25 no.8
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• pp.1171-1176
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• 2004

Three banana-shaped achiral compounds, 4-chloro-1,3-phenylene bis [4-{4-(undecenyloxy)phenyl imino-methyl} benzoate] derivatives, were synthesized with variation of a substituent (x=H, F, Cl); their antiferro-electric properties are described. The smectic mesophases, including a switchable chiral smectic C(Sm $C^{\ast}$) phase, were characterized by differential scanning calorimetry, polarizing optical microscopy, triangular wave method, and X-ray diffractometry. The presence of vinyl groups at the terminals of linear side wings in the banana-shaped achiral molecules induced a decrease in melting temperature and formation of the switchable Sm $C^{\ast}$ phase in the melt. The smectic phase having a lateral fluorine-substituent at 3-position of the Schiff's base moiety showed antiferroelctric switching, and the value of spontaneous polarization on reversal of an applied electric field was 250 nC/$cm^2$ .

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.581-584
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• 2003

Most modeling about dynamic behavior of Antiferroelectric Liquid Crystal (AFLC) is limited to the hysteric characteristics of AFLC cells or thresholdless switching of frustrated AFLC cells. In this paper, domain growth of AFLC cells is modeled with extended bilayer model. When driving pulses that consist of a selection voltage, a bias voltage, and a reset voltage are applied to the AFLC cell, its dynamic behavior is simulated.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.445-448
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• 2002

New banana-shaped achiral compounds, 1,3-phenylene bis [4-{4-(7-octenyloxy)phenyliminomethyl}benzoate](PBOEB), 1,3-phenylene bis [4-{3-fluoro-4-(7-octenyloxy)phenyliminomethyl}benzoate] (PBFOEB), 1,3-phenylene bis [4-{4-(10-undecyloxy)phenyliminomethyl}benzoate](PBEUB), and 1,3phenylene bis [4-{3-fluoro-4-(10-undecyloxy)phenyliminomethyl}benzoate](PBFEUB) were obtained by general synthetic methods. PBOEB and PBFOEB having the octenyloxy groups such as $-(CH_2)_6CH=CH_2$ showed ferroelectric switching, and their values of spontaneous polarization on reversal of an applied electric field were 120 nC/$cm^2$ and 225 nC/$cm^2$, respectively. PBEUB and PBFEUB having the undecyloxy groups such as $-{CH_2)_9CH=CH_2$ showed antiferroelectric switching, and their values of spontaneous polarization on reversal of an applied electric field were 120 nC/$cm^2$ and 140 nC/$cm^2$, respectively. We could obtain ferroelectric and antiferroelectric phases by controlling the number of carbon atom in alkenyloxy chains of bent-core molecules.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.108-109
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• 2000

1988년 Chandani와 동료 연구원들에 의해 처음으로 반강유전성 액정 MHPOBC$^{(1)}$ 를 발견한 이래로 이 반강유전성을 디스플레이에 적용하기 위한 여러 가지 노력이 진행되고 있다. $^{(2).(3)}$ 또한 최근에는 thresholdless antiferroelectric liquid crystal(TLAF)을 이용하여 TFT-LCD에서 완전한 동화상을 구현하려는 연구가 활발하게 진행되고 있으며, 이미 Toshiba 연구소에서는 TFT-TLAF-LCD 시제품을 시연한 바도 있다.$^{(4)}$ 하지만 이러한 시제품은 아직 약하게 히스테리시스가 있고, AC 구동시에 contrast 비가 낮은 등 여러 가지 문제점이 있기 때문에 제품을 양산하지 못하고 있다. 이러한 문제점들은 배향제 및 액정의 재료개발과 구동방법 개발을 통해서 해결할 수 있는데, 아직 반강유전성 및 TLAF 액정의 스위칭 특성에 대한 메카니즘이 명확하게 규명되어 있지 않았기 때문에 쉽게 가시적인 성과를 얻지 못하고 있는 실정이다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.112-113
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• 2000

주변의 광원을 이용하는 단일 편광판 반사형 액정 표시장치는 전력 소모의 70%이상을 차지하는 배면조명이 필요 없으므로 가볍고 얇으며, 소비전력이 적고, 큰 반사효율을 얻을 수 있는 장점으로 인해 큰 주목을 받고 있다. 현재 단일 편광판 반사형 액정 표시장치는 reflective TN(RTN)$^{(1)}$ 과 mixed-mode TN(MTN)$^{(2)}$ 과 같은 TN액정 모드를 기본적으로 사용하고 있다. 하지만 TN액정 모드를 사용한 반사형 액정 표시장치는 좁은 시야각과 느린 응답 특성 등의 문제점이 있다. 이러한 문제점들을 해결하기 위해 reflective-optically compensated bend(R-OCB)$^{(3)}$ 및 reflective homeotropic TN mode$^{(4)}$ , 반사형 BTN$^{(5)}$ 등을 이용한 반사형 액정 표시장치 등이 보고된 바 있다. (중략)

• Journal of the Optical Society of Korea
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• v.5 no.2
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• pp.39-42
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• 2001

A new method of switching mode in AFLC cell is proposed for faster switching time and higher contrast ratio. In this mode the ″dark″ state is obtained by applying negative full voltage while the ″bright″ state is achieved by applying positive full voltage to the cell. The switching time is reduced to 100 $mutextrm{s}$ for the cell whose switching time is 22 ms when operated in conventional mode. The contrast ratio is also improved vastly with this method. The possibility of achieving gray scale was shown in this mode of operation.

• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.235-239
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• 2001

In this paper, we propose an optical configuration of a reflective AFLC display mode using a half-wave AFLC cell in which inplane tilt angle is $22.5^{\circ}C$. To check the validity of our design, we fabricate a reflective half-wave AFLC cell of which the in-plane tilt angle is $24.9^{\circ}C$, and measure viewing angle and visible spectra characteristics. In the results, the half-wave AFLC cell in the reflective configuration exhibits wide viewing-angle as well as high brightness and contrast. trast.