• 한국전기전자재료학회논문지
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• 제13권2호
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• pp.157-162
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• 2000

The electro-optical characteristics of TN(twisted nematic)-LCD(liquid crystal display) with photo-dimerized on a PMCh(poly(4'methacryoyloxylchalcone)) surface using a new photo-dimerization method was studied. The excellent voltage-transmittance(V-T) curve of TN-LCD with photo-dimerized on a PNCh surface for 1 min. using a new photo-dimerization method was observed. Also, the voltage-hold-ing-ratio(VHR) of TN-LCD with photo-dimerized on a PMCh surface using a new photo-dimerization method is higher than that of conventional photo-dimerization method. Consequently, we suggest that the new photo-dimerization method. Consequently, we suggest that the new photo-dimerization method for LC aligning is the most promising rubbing-free techniques.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.541-544
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• 1999

We synthesised a novel photo-alignment material of PCEMA (poly(cinnamolyethyl methacrylate)) on photo-dimerization reaction. Next we investigated the electro-optical (EO) characteristics of photo-aligned twisted nematic (TN)-liquid crystal display (LCD) with linearly polarized ultraviolet (UV) light irradiation on PCEHA surface. The excellent voltage-transmittance characteristics of photo-aligned TN-LCD on PCEMA surface were obtained. The threshold voltage of photo-aligned TN-LCD decreases with increasing the UV light irradiation time on PCEMA surface. Also, the response time of photo-aligned TN-LCD on PCEMA surface is almost the same as rubbing-aligned TN-LCD.

• 폴리머
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• 제30권5호
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• pp.417-421
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• 2006

신나모일 그룹의 광배향 메커니즘과 공정 조건들과의 관계를 이해하기 위하여 폴리(실록산 신나메이트) (PSCN)를 이용한 광배향 연구를 진행하였다. DSC와 편광현미경 실험에서 PSCN의 등방성 온도는 $105^{\circ}C$ 이상이었으며 액정 온도 구간에서 한 번 배열된 분자들은 저온이나 고온의 등방성 온도 구간에서도 없어지지 않는 열안정성을 보였다. UV/Vis 흡수 실험을 통해서는 광이량화 반응이 주된 광배향 반응이며 신나모일기가 스스로 배열되는 경향이 강하여 광이량화 반응의 효율을 높이는데 기여하지만 광조사가 지나칠 경우 경쟁 관계에 있는 photo-fries 반응이 증가하여 오히려 광배향 성질이 떨어짐을 알 수 있었다. 한편, photo-fries 반응은 UV의 파장을 조절하여 억제할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.835-838
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• 2000

A new photo-alignment material, copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy) chalcone-cholesterol methacrylate) was synthesized and the electro-optical (EO) characteristics for the photo-aligned vertical-aligned (VA)-LC display (LCD) were studied. Good voltage-transmittance (V-T) and response time characteristics for the photo-aligned VA-LCD with polarized UV exposure on the copolymer-1 (2%) surfaces for 1 min. were observed. EO performance for the photo-aligned VA-LCD decreased with increasing UV exposure time on a copolymer surface. Also, excellent V-T and response time characteristics for the photo-aligned VA-LCD with UV exposure on copolymer-2 and copolymer-3 surfaces for 3min. can be achieved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.141-144
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• 2000

New photo-alignment materials based on PCEMA (Poly (4-methacryloyloxylchalcone)) for liquid crystal (LC) aligning were synthesized. And the electro-optical (EO) characteristics of the photo-aligned TN-LCD were investigated. The excellent LC alignment and voltage-transmittance (V-T) characteristics for the photo-aligned TN-LCD on PCEMA surface containing more cinnamoly group can be achieved. However, the reverse tilt disclinations for the photo-aligned TN-LCD on the PCEMA surface containing more OH group were observed. Consequently, we suggest that the LC aligning capabilities can be increased by increasing of cinnamoly group on the PCEMA surfaces.

• 한국전기전자재료학회논문지
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• 제13권3호
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• pp.235-240
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• 2000

New photh-alignment materials based on PCEMA (poly(4-methacryloyloxylchalcone))for liquid crystal (LC) aligning were synthesized. and the electro(EO) characteristics of the photo-aligned TN-LCD were investigated. The excellent LC alignment and voltage-transmittance (V-T) characteristics for the photo-aligned TN-LCD on PCEMA surface containing more cinnamoly group can be achieved. However the reverse tilt disclinations for the photo-aligned TN-LCD on the PCEMA surface containing more OH group were observed. Consequently we suggest that the LC aligning capabilities can be increased by increasing of cinnamoly group on the PCEMA surfaces.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.181-184
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• 2000

A new photo-alignment material, copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy) chalcone-chalconemethacryl) was synthesized and the electro-optical (EO) characteristics for the photo-aligned vertically aligned (VA)-LC display (LCD) were investigated. The monodomain alignment of the NLC for the photo-aligned VA-LCD by linearly polarized UV exposure on the photo-dimerized copoly (PM4Ch-ChMA) surfaces was observed. Excellent voltage-transmittance characteristics for the photo-aligned VA-LCD by UV exposure for 1 min. on the copoly (PM4Ch-ChMA) surfaces were achieved. The response time of the photo-aligned VA-LCD by UV exposure on for 1 min. the copoly (PM4Ch-ChMA) surfaces was about 39.3 ms. The response time for the photo-aligned VA-LCD decreased with increasing UV exposure time.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1163-1166
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• 2004

Cinnamate group is well-known for the dimerization reaction by ultra-violet irradiation and cinnamate polymers are studied for photo-alignment materials. The cinnamate groups of flexible polymer are found to produce LC alignment parallel to polarization direction of ultra-violet light, which is contrary to the LC orientation on conventional cinnamate polymers. The un-reacted cinnamate groups in the flexible polymer are also found to participate in cycloadducts formation by additional thermal reaction that preserves the orientation of cycloadducts, leading to the enhancement of thermal stability of LC alignment.

• 한국전기전자재료학회논문지
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• 제13권7호
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• pp.625-629
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• 2000

We synthesized a new copoly (PM4Ch-ChMA) copoly(poly(4-methacryloyloxy) chalcone-cholesteryl methacrylate) having chalconyl and cholesteryl moiety for homeotropic liquid crystal(LC) alignment. Pretilt angles of nematic(N) LC generated by linearly polarized UV exposure on the copolymer surfaces were investigated. Good thermal stabilities of the synthesized copolymer were obtained by TGA (Thermogravimetric Analysis) measurement. Pretilt angles of the NLC decreased with increasing UV exposure time on the copolymer surfaces. We consider that the pretilt angle of the NLC is attributed to increased chalcone by increased UV exposure time. High pretilt angle of the NLC is attributed to increased chalcone by increased UV exposure time. High pretilt angle of 81$^{\circ}$was observed after the UV exposure for 3 min.

• BMB Reports
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• 제32권3호
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• pp.215-225
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• 1999

Phytochromes (with gene family members phyA, B, C, D, and E) are a wavelength-dependent light sensor or switch for gene regulation that underscore a number of photo responsive developmental and morphogenic processes in plants. Recently, phytochrome-like pigment proteins have also been discovered in prokaryotes, possibly functioning as an auto-phosphorylating/phosphate-relaying two-component signaling system (Yeh et al., 1997). Phytochromes are photochromically convertible between the light sensing Pr and regulatory active Pfr forms. Red light converts Pr to Pfr, the latter having a "switch-on" conformation. The Pfr form triggers signal transduction pathways to the downstream responses including the expression of photosynthetic and other growth-regulating genes. The components involved in and the molecular mechanisms of the light signal transduction pathways are largely unknown, although G-proteins, protein kinases, and secondary messengers such as $Ca^{2+}$ ions and cGMP are implicated. The 124-127 kDa phytochromes form homodimeric structures. The N-terminal half contains the tetrapyrrolic phytochromobilin for red/far-red light absorption. The C-terminal half includes both a dimerization motif and regulatory box where the red light signal perceived by the chromophore-domain is recognized and transduced to initiate the signal transduction cascade. A working model for the inter-domain signal communication within the phytochrome molecule is proposed in this Review.