• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.293-294
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• 2009

We proposed a novel single gap transflective liquid crystal display (LCD) using liquid crystal with negative dielectric anisotropy. We designed cell structure driven by fringe electric field in the transmissive (T) part and vertical electric field in the reflective (R) part. In the device, high surface pretilt angle of the LC in the R-part is achieved through polymerization of an UV curable reactive mesogen (RM) monomer at surfaces. By optimizing the parameters, a newly developed transflective display has characteristics such as single gap and single gamma curve.

• 공업화학
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• 제5권5호
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• pp.857-861
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• 1994

독성이 있는 아크릴 모노머를 비닐에테르로 대체시켜 우레탄아크릴레이트와 배합시키는 것을 특징으로 하는 자외선 경화형 하이브리드 시스템을 조사하였다. 일반적으로 하이브리드 시스템의 코팅 물성은 자유 라디칼계보다은 우수하나 양이온계보다는 열세하게 나타났다. 아크릴계 올리고머 함량이 70% 이상으로 배합된 경우의 하이브리드계는 코팅물성과 경화물성면에서 자유라디칼계와 양이온계보다 뛰어나게 나타났다. 다양한 코팅 시스템의 경화과정을 조사하기 위해서 광열분석기를 적용하였다. 그 결과 코팅 배합물의 경화속도에 미치는 결정적인 인자는 배합물 특성에 따라 달라짐을 알 수 있었다. 동류의 하이브리드계의 경우에는 광경화개시제의 효율보다는 모노머/올리고머 비가 더욱 중요함을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 및 기술 세미나 논문집 디스플레이 광소자
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• pp.51-52
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• 2008

A single gap transflective liquid crystal display(LCD) driven by fringe electric field in the transmissive(T) region and vertical electric field in the reflective(R) region was designed. Because the pretilt angle is formed in $53^{\circ}$ through polymerization of an UV curable reactive mesogen(RM) monomer at the surface, the effective cell retardation $(d{\Delta}n_{eff})$ value of the R region becomes half of that in the T region where the LCs are homogenously aligned. Consequently, a transflective display driven by a vertical and fringe electric field with a single cell gap and single gamma curves is realized.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.339-340
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• 2008

The Conventional PVA (patterned vertical alignment) mode showed characteristics of 8-domain using T-T type or C-C type. But these methods have disadvantages such as decreasing aspect ratio and transmittance. In order to resolve these problems, in this paper we have studied a new 8-domain method which is partially using the UV curable reactive mesogen (RM) that is a role in surface stabilization. The characteristic of off-axis color shift is decreased because the part of surface stabilized area is compensated to other area in a pixel. Consequently, the device shows improved color shift by 8-domain.

• 한국생산제조학회지
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• 제20권6호
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• pp.756-760
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• 2011

This paper proposed an alignment stage driven by piezo actuators for alignment process of a contact-type lithography. Among contact-type lithography processes, an UV-curable nanoimprint process is an unique process to be able to align patterns on upper and lower layers. An alignment stage of the UV-curable nanoimprint process requires nano-level resolution as well as high stiffness to overcome friction force due to contact moving. In this paper, the alignment stage consists of a compliant mechanism using flexure hinges, piezo actuators for high force generation, and capacitive sensors for high-resolution measurement. The compliant mechanism is implemented by four prismatic-prismatic compliant chains for two degree-of-freedom translations. The compliant mechanism is composed of flexure hinges with high stiffness, and it is directly actuated by the piezo actuators which increases the stiffness of the mechanism, also. The performance of the ultra-precision stage is demonstrated by experiments.

• Macromolecular Research
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• 제14권5호
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• pp.517-523
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• 2006

The effects of particle content, size and shape on the thermal conductivity (k) and adhesion properties of thermally conductive, pressure-sensitive adhesives (PSAs) were investigated. The matrix resins were thermally crosslinkable, 2-ethylhexyl acrylic polyol and ultraviolet (UV)-curable, random copolymer consisting of acrylic oligomer and various acrylates. We found that k increased with increasing diameter and particle aspect ratio, and was further enhanced due to the reduction of the interfacial thermal barrier when the coupling agent, which increases the adhesion between particles and the matrix resin, was used. On the other hand, adhesion properties such as peel strength and tack of the thermally crosslinkable resin decreased sharply with increasing particle content. However, for UV curable resin, increased particle addition inhibited the decrease in adhesion properties.

• 한국재료학회지
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• 제27권4호
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• pp.199-205
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• 2017

In this study, (3,4-epoxycyclohexane)methyl 3,4-epoxycyclohexylcarboxylate acrylate was synthesized by reacting (3,4-epoxycyclohexane)methyl 3,4-epoxycyclohexylcarboxylate with acrylic acid to minimize hardening shrinkage and to improve heat resistance, which are known as disadvantages of photopolymers for 3D printing application. Urethane acrylate was synthesized by reacting 1,3,5-triazine-2,4,6-triamino alcohol, 2-hexylethyl acrylate, and isophorone diisocyanate in order to improve the mechanical properties without deteriorating the heat resistance. The physical properties before and after the synthesis of the acrylate and the mechanical properties when the urethane acrylate was applied were investigated. The reaction progress of the composite was examined by FTIR and $^{13}C$ NMR. The heat deflection temperature, flexural strength, and surface hardness of the molding were measured. The curing behavior by Photo-DSC ultraviolet irradiation was also examined.

• 한국세라믹학회지
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• 제56권5호
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• pp.461-467
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• 2019

Ink-jet printing technology, which utilizes a digitalized design to print fine ink directly on a substrate, has been of interest in various industries due to its high efficiency and adaptability to various materials. Recently, active attempts have been made to apply ceramic materials having excellent heat resistance, light resistance, and chemical resistance to the ink-jet printing process. In this study, ceramic ink was synthesized by combining ceramic pigments with UV curable polymer. 3D printability at various contact angles between ceramic ink and substrate was analyzed in detail. Rheological properties of the synthesized ceramic ink were optimized to meet the requirements of the ink-jet printing process, and the contact angle of UV curable ceramic ink was controlled through surface treatment of the substrate. The potential for additive manufacturing of ceramic material using ink-jet printing was investigated by analyzing the effect of contact angle control on ceramic ink droplets and their 3D printability.

• 한국염색가공학회지
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• 제34권4호
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• pp.217-223
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• 2022

Flame-retardant finished silk fabrics could release carcinogenic formaldehyde resulting from the conventional finishing agents. New water-soluble cyclophosphazene derivative can be used as a formaldehyde-free flame retardant for the silk protein. Dichloro tetrakis{N-[3-dimethylamino)propyl]methacrylamido}cyclophosphazene(DCTDCP) can be cured by heat or UV irradiation as a durable flame retardant for the silk fabrics. Treatment conditions were optimized including curing temperature and time, finishing formulations, and UV energy. At the 30% DCTDCP application, peak HRR and THR decreased by 42.6% and 49.6% respectively compared to the pristine silk fabrics. Also char residue increased up to 48% from 11% indicating solid-phase retarding mechanism. The flame-retardant silk fabrics showed a LOI of 31.1 and the washed sample maintained a LOI of 26.8 even after ten laundering cycles.

• 한국정밀공학회지
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• 제32권9호
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• pp.781-786
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• 2015

Recently, studies of 3D printing methods have been working in various applications. For example, the powder base method laminates the prints by using a binding or laser sintering method. However, the draw back of this method is that the post process is time consuming and does not allow for parts to be rapidly manufactured. The binding method requires the post process while the time required for the post process is longer than the manufacturing time. This paper proposes a UV curing binding method with an integrated piezo printing head system. The optimization of an arbitrary waveform generation for the control of a UV curable resin droplet was researched, in addition to developed optimized UV curing processes in multi nozzle ink jet heads.