• 한국위성정보통신학회논문지
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• 제10권2호
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• pp.75-79
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• 2015

본 연구에서는 폴리이미드 박막위에서의 수직 및 수평배향에서 혼합액정의 배향 특성에 대해서 연구하였다. 혼합액정은 러빙을 이용하여 배향처리하였으며, 러빙에 사용된 폴리이미드 박막은 알킬기를 Side Chain으로 가진 수직배향용 배향막과 그렇지 배향막으로 나누어서 프리틸트각 특성을 측정하였다. 실험결과 혼합액정을 사용하여 양호한 배향상태를 얻을 수 있었으며, 고온에서의 열 안정성에서도 우수한 특성을 보이는 것을 알 수 있었다. 또한 프리틸트각의 발생 원리를 이해하기 위해서 접촉각 측정을 실시하였으며, 이 둘이 밀접한 상관관계를 갖고 있음을 알 수 있었다

• 복식문화연구
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• 제24권6호
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• pp.817-824
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• 2016

The introduction of natural dyes into modern dye houses is very promising green chemistry concept that should be popularized more to reduce the dependency of leather dyeing on some toxic and non-biodegradable synthetic dyes. In this study, the properties of dyeing of cochineal on cow leather were evaluated. The proper dyeing conditions were identified with dye uptake (K/S values) depending on the colorant concentration, dyeing duration, dyeing temperature, and dye bath pH. For the proper mordanting conditions, color changes for different mordants were observed as $La^{*}b^{*}$ and H V/C values. Color fastness (light, rubbing, and dry cleaning) was also examined. Additionally, antibacterial properties and UV protection were examined. The results were as follows: The optimized dyeing conditions were 300% o.w.f., $40^{\circ}C$, 40 min., and pH 5. The cow leather color was red in the absence of mordanting, while it was red purple after being mordanted with Al and Cu, and purple mordanted with Fe. The K/S value of cow leathers increased in the order of the dyeing using $AlK(SO_4)_2$ > $CuSO_4$ > $FeSO_4$. The colorfastness to light and rubbing were reduced compared to original (untreated) cow leather. However dry cleaning fastness was very satisfactory, with a 4~5 rating. The dyed and pre-mordanting dyed cow leather showed excellent antibacterial properties.

• Transactions on Electrical and Electronic Materials
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• 제3권4호
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• pp.36-40
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• 2002

The polar anchoring strength and surface ordering in a NLC,4-n-pentyl-4'-cyanobiphenyl (5CB), on a rubbed polyimide (PI) surface containing trifluoromethyl moiety were studied. The large extrapolation length de of 5CB for washing process of water was measured at RS=114 mm. The polar anchoring energy of 5CB on the rubbed PI surface is decreased by the washing process. Also, the polar anchoring energy of 5CB increases with the rubbing strength on the PI surface. The surface ordering of 5CB for all washing processes is smaller than the non-washing process; it is attributed to the washing process.

• Tribology and Lubricants
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• 제28권3호
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• pp.117-123
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• 2012

Tribological properties of hybrid type friction materials were studied. Hybrid friction materials were produced by combining non-steel(NS) and low-steel(LS) type friction materials. The emphasis of the investigation was given to possible synergistic effects from the two different friction materials, in terms of friction stability at high temperatures and the amplitude of friction oscillation, also known as stick-slip at low sliding speeds. The high temperature friction test results showed that the friction effectiveness of the hybrid friction material was well sustained compared to LS and NS friction materials. Wear resistance of the hybrid type was similar to LS friction materials. Examination of the rubbing surfaces after tests revealed that the friction characteristics of the hybrid friction material were attributed to the wear debris produced from low-steel friction materials, which were migrated to the surface of the non-steel friction material, forming new contact plateaus. The stick-slip amplitude and its frequency were pronounced when non-steel friction material was tested, while hybrid and low-steel types showed relatively small stick-slip amplitudes. These results suggest possible improvement of tribological properties by designing a hybrid composite of low-steel and non-steel friction materials.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1585-1587
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• 1997

We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in the cell with slanted non-polarized ultraviolet (UV) light irradiation on two kinds of the polyimide (PI) film. It was shown that the monodomain alignment in NLC is obtained in the cell with slanted non-polarized UV light irradiation on PI surface. The pretilt angle of NLC is generated about 3 degrees in the cell with slanted non-polarized UV light irradiation with 70 degrees on PI surface without side chain. But, the pretilt angle of NLC is generated about 1 degree in the cell with slanted non-polarized UV light irradiation with 80 degrees on PI surface with side chain. We consider that the pretilt angle generation in NLC is attributted to anisotropic dispersion force between the LC molecular and the PI surface.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 및 기술 세미나 논문집 디스플레이 광소자
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• pp.44-44
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• 2008

To date, rubbing has been widely used to align LC molecules uniformly. Although rubbing can be simple, it has fundamental problems such as the generation of defects by dust and static electricity, and difficulty in achieving a uniform LC alignment on a large substrate. Therefore, non contact alignment has been investigated. Ion beam induced alignment method, which provides controllability, nonstop process, and high resolution display. In this study, we investigated liquid crystal (LC) alignment with ion beam (IB) that non contact alignment technique on polyimide and electro-optical characteristics of twisted nematic (TN)-liquid crystal display (LCD) on the polyimide under various ion beam angles. In this experiment, Polyimide layer was coated on glass by spin-coating and Voltage-transmittance(VT) and response time characteristics of the TN cell were measured by a LCD evaluation system. The good characteristics of the nematic liquid crystal (NLC) alignment with the ion beam exposure polyimide surface was observed. The tilt angle of NLC on the PI surface with ion beam exposure can be measured under $1^{\circ}$ for all of irradiation angles. In addition, it can be achieved the good EO properties, and residual DC property of the ion beam aligned TN cell on polyimide surface.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.911-917
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• 1998

In this paper, we have investigated the generation of pretilt angle for nematic liquid crystal (NLC) in a cell with oblique non-polarized ultraviolet(UV) light irradiation polyimide (PI) surface. It was found that the monodomain alignment of the NLC is obtained with an angle of incidence of 70∼85。 on PI surface. It is considered that the monodomain alignment of NLC is attributed to anisotropic of NLC is about 3。 with and angle of incidence of 70∼75。. Finally, we observed that the voltage-transmittance, response time, and voltage-holding-ratio(VHR) characteristics of photo-aligned twisted nematic(TN)-LCD with and angle of incidence of 85。 on PI surface were almost same compared to rubbing -treated TN-LCD.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.545-548
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• 1999

The electro-optical characteristics of photo-aligned vertical-alignment (VA)-liquid crystal display (LCD) with non-polarized ultraviolet (UV) light irradiation of 45\`on homeotropic polyimide (Pl) surface were investigated. LC alignment on photo-aligned VA-LCD is attributed to photo-depolymerized reaction of the polymer with non-polarized UV light irradiation on PI surface. We had good voltage-transmittance (V-T) characteristics of photo-aligned VA-LCD. The response time of photo-aligned VA-LCD was slower than that of the rubbing-aligned VA-LCD. Finally, we suggest that the slow response time of photo-aligned VA-LCD depends on the LC domain.

• 한국염색가공학회지
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• 제27권2호
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• pp.105-112
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• 2015

In order to detect gas phase strong acid on fabrics, a hexyl-substituted monoazo yellow dye, which was the modified form of a conventional pH-indicating dye, Methyl Yellow, was studied in view of acid-gas sensing properties and its fastness. The dye was printed on polypropylene non-wovens for protective coveralls and examined under various conditions of strong acid such as hydrochloric acid. The dye showed color change from yellow to red on exposure to gas phase hydrochloric acid as low concentration as 1~3 ppm very instantly. Considering reuse of the dye-printed non-wovens, the repeatability of color change was tested on the same sample for 50 repeats and 100 days. The acid-gas sensing function was maintained almost the same level of initial performance. The color fastness of the dye on polypropylene non-wovens was very good showing higher than ratings 4 except for 3~4 to rubbing under wet condition.

• 패션비즈니스
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• 제20권4호
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• pp.88-95
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• 2016

This paper investigated to the effectiveness of an eco-friendly method for oiling cow leather. After leather was lac-dyed with a vegetable leather processing solution and a mordant, olive oil was used to treat the leather. Changes in surface color and dyeability, light fastness, rubbing fastness, and water fastness were measured. An increase in dyeability caused by the mordant appeared in all the samples. The dyeability of leatger treated with Cu-mordant was higher than that treated with Fe-mordant and Al-mordant, and the three times greater than when no mordant was used. Dyeability after oiling more than doubled compare with before oiling. An increase in dyeability by oiling was highe greater than doubled compared with before oiling. The non-mordant-treated samples exhibited a 5-fold increase in dyeability, and the other samples showed more than two times more dyeability than did non-oiled samples. A color difference of more than 20.0-fold appeared in all samples, and the differences in lightness and chroma were greater than were the differences in other color factors. The colors after oiling were measured R, P, and PB. Light fastness improved in all samples after oiling, and all of the measurements were reduced in the order of Fe-mordant> Cu-mordant> Al-mordant ${\geq}$non mordant.