• 청정기술
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• 제22권3호
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• pp.203-207
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• 2016

Here, we report a novel fabrication technique for patchable organic lasing sheet based on non-volatile liquid organic semiconductors and freestanding polymeric film with high flexibility and patchability. For this work, we have fabricated the second-order DFB grating structure, which leads to surface emission, embedded in the freestanding polymeric film. Using an ultra-violet (UV) curable polyurethaneacrylate (PUA) mixture, the periodic DFB grating structure can be easily prepared on the freestanding polymeric film via a simple UV curing process. Due to unsaturated acrylate remained in the PUA mixture after UV curing, the freestanding PUA film provides adhesive properties, which enable mounting of the patchable organic lasing sheet onto non-flat surfaces with conformal contact. To achieve laser actions in the freestanding resonator structure, a composite material of liquid 9-(2-ethylhexyl)carbazole (EHCz) and organic laser dyes was used as the laser medium. Since the degraded active materials can be easily refreshed by a simple injection of the liquid composite, such a non-volatile liquid organic semiconducting medium has degradation-free and recyclable characteristics in addition to other strong advantages including tunable optoelectronic responses, solvent-free processing, and ultimate mechanical flexibility and uniformity. Lasing properties of the patchable organic lasing sheet were also investigated after mounting onto non-flat surfaces, showing a mechanical tunability of laser emission under variable surface curvature. It is anticipated that these results will be applied to the development of various patchable optoelectronic applications for light-emitting displays, sensors and data communications.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.141-145
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• 2005

Since the electromagnetic properties of fiber reinforced polymeric laminate composite can be tailored effectively by adjusting its composition and regulating the stacking sequence, it is plausible material for fabricating the radar absorbing structures (RAS) of desired performance. In order to design the effective electromagnetic wave (EM) absorber with the fiber reinforced polymeric laminate composite, its electromagnetic characteristics should be available and could be regulated easily in the target frequency bands. In this study, dielectric characteristics of the E-glass/epoxy laminate composites were measured by the free space method in the X-band frequency range ($8.2\;{\sim}\;12.4\;GHz$). In order to describe the dielectric behavior of laminate composites of arbitrary stacking sequences, the equivalent circuit model and the laminating equations for estimating dielectric properties were proposed, and experimentally verified. From the comparison of the predicted and measured data, the proposed method predicted well the experimentally measured data.

• 한국세라믹학회지
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• 제31권11호
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• pp.1271-1282
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• 1994

The surface of commercial alumina fibers used for reinforcing the MCFC matrix has been coated with ${\gamma}$-LiAlO2 being the same material as the matrix, by the sol-gel method in order to enhance the corrosion resistivity of alumina fibers. Stable LiAlO2 complex polymeric sols for coating was synthesized by mixing aluminum alkoxide polymeric sols with LiNO3 solution. It was found that the LiAlO2 polymeric sol prepared by adding the mixed chelate of acethylacetone and triethanolamine (the mole ratio of AA/TEA = 0.125/0.75) to the 1 mole of the aluminum alkoxide had the excellent stability and coating behavior. The crystalline structure of the dried gel from the ${\gamma}$-LiAlO2 sol was completely transformed into the ${\gamma}$-LiAlO2 at $600^{\circ}C$. The optimum viscosity of the sol for coating the alumina long fibers was 30~40 cP, while it was 12~20 cP in case of the short fiber coating. The ${\gamma}$-LiAlO2 coated alumina fibers without defects fully densified when heat-treated at 120$0^{\circ}C$.

• 한국세라믹학회지
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• 제36권2호
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• pp.151-158
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• 1999

유기단분자인 $\varepsilon$-Caprolactame을 montmorillonite의 층사이에 삽입하여 증합반응시켜 고분자화해 줌으로써 무기고분자와 유기고분자를 화학결합에 의해 연결시켜 주었다. X-선 및 IR-분석결과 층내에서의 $\varepsilon$-Caprolactame의 고분자반응이 성공적으로 이루어졌음이 입증되었다. 고분자 반응생성물을 좀 더 자세히 분석조사하기 위해 고분자 물질을 층사이로부터 격리시켜 X-선회절분석 및 IR 분석한 결과와 montmorillonite없이 $\varepsilon$-Caprolactame만 고분자화시켜 얻은 순수고분자에 대한 동일한 분석 결과를 비교해 본 결과 서로 동일한 화합물임이 입증되었다.

• 접착 및 계면
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• 제3권1호
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• pp.13-19
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• 2002

We have studied on the surface and adhesion properties for acrylic terpolymers, having both hydrophobic and hydrophilic side chains, synthesized via solution polymerization. In order to develop a waterborne material. we tried to synthesize these terpolymers via emulsion polymerization. The polymeric emulsion synthesized was mainly composed of methyl methacrylate (MMA), methoxy-polyethyleneglycol methacrylate (MPEGMA) having hydrophilic side chains and methoxypolypropyleneglycol methacrylate (MPEGMA) having hydrophobic side chains. The viscosities of this series increased with an increase in the content of the co-monomer such as MPEGMA and (MPEGMA). This behavior resulted in the increase in the diameter and heterogeneity of the emulsion particle via AFM observation. Furthermore. the tensile adhesion strength and 90-degree peel strength of the adhesive of these polymeric emulsions were measured. In the case of polymeric emulsion composed of the same content of both hydrophilic and hydrophobic component, the adhesion property showed the highest value. However, since the adhesion properties as a practical applicable adhesive were poor, some improvements were required. When the composition above was modified with butyl acrylate (BA), the improvement effect on adhesion strength was accepted. In particular, 90-degree peel strength increased up to a maximum of 400% of the original value.

• 대한화학회지
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• 제42권4호
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• pp.487-500
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• 1998

A bird's-eye view on preparation, structure and properties of polymeric complexes in the field of Inorganic-Organic-Hybrids is presented in the view point of solid state and materials chemistry. These materials are useful precursors for preparing nanoparticles and fine grain oxides. Some of them are electroactive and are used as protonic or lithium electrolytes, electrochromic materials or membranes for sensors and actuators. New results on bio-hybrids, a class of material not far from polymeric complexes, are also described.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.631-632
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• 2011

• 한국자동차공학회논문집
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• 제18권4호
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• pp.121-126
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• 2010

The automotive weather strip has functions of isolating of water, dust, noise and vibration from outside. To achieve good sealing performance, weather strip should be designed to have the high contact force and wide contact area. However, these design causes excessive permanent deformation of weather strip. The causes of permanent deformation is generally explained to be the chemical material detrioration and physical variation and cyclic loading, etc. This paper introduces a numerical method to predict the permanent deformation using the time dependent viscoelastic model which is represented by Prony series in ABAQUS. Uniaxial tension and creep tests were conducted to obtain the material data. And the lab. test for the permanent deformation was accelerated during shorter time, 300 hours. The permanent deformation of weather strip was successfully predicted under the different loading conditions and different section shapes using the suggested numerical process.

• 폴리머
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• 제30권6호
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• pp.550-555
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• 2006

잉크젯프린터용 잉크가 수성화되어 감에 따라 전용 인화지에 사용되는 코팅제 역시 수성 코팅제가 사용되고 있는 추세이다. 이 수성 코팅제에 사용되는 재료를 살펴보면 안료로는 알루미나솔, 주 바인더로 폴리 (비닐 알콜), 부족한 물성을 향상시키기 위해 고분자 첨가제를 사용한다. 된 연구에서 사용된 고분자 첨가제는 스티렌과 부틸아크릴레이트를 기본으로 하구 메타크릴산, 아크릴산, 아크릴 아미드 단량체들을 조합하여 에멀션 중합법으로 합성하였다. 중합시 비이온 및 음이온 유화제를 혼합 혹은 단독으로 사용하고, 단량체 조합과 고분자 첨가제의 입자구조를 변화시켜 흡수성, 퍼짐성, 광학밀도의 인쇄적성과 광택도 내수성 등의 변화를 살펴보았다. 이 결과, 음이온 유화제나 카복실기를 가지는 아크릴산 같이 음이온성이 큰 물질을 사용한 경우 알루미나 솔과의 상용성에서 문제를 야기하였고 아크릴 아미드는 인쇄적성에서 뛰어난 결과를 얻었지만 광택도가 떨어지는 경향을 알 수 있었다. 메타크릴산이 함유된 경우 광택도는 향상되었지만 인쇄적성이 떨어졌다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1249-1250
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• 2004

In this paper, we report new technique of preparation of material for flexible displays and E-paper technology. This material represents porous polymeric fiber based on polyacrylonitrile filled by liquid crystal.