• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.6
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• pp.446-450
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• 2005

We have built a spherically focused, not using acoustic mirrors, capacitive micromachined air-coupled ultrasonic transducer. A flexible backplate of a copper/polyimide backplate is used, permitting it to conform to a spherically shaped substrate. The backplate is patterned with $40-{\mu}m$ depressions having $80-{\mu}m$ center-to-center spacing. A $6-{\mu}m$ thick aluminized Mylar film completing the transducer is deformed to allow it to conform to the spherical backplate. The device's frequency spectrum is centered at 805kHz with -6dB points at 440 and 1210kHz.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1450-1451
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• 2008

To investigate the reliability of the conductive lines patterned by ink-jet printing, we evaluated the reliability of the ink-jet printed silver (Ag) patterns according to the guide lines built up as assessments methods in the production of conventional rigid printed circuit boards. The assessment methods include the uniformity of line width and space, adhesive strength, dielectric withstand, solder float, thermal shock test and pressure cooker test (PCT). To prepare assesment vehicles, different regular test patterns were created by Ag ink-jet printing on the same polyimide substrate for each of assessment methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.4
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• pp.721-726
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• 2017

We fabricated stretchable thin-film transistors(TFTs) on a polydimethylsiloxane substrate with patterned polyimide island structures by using an amorphous InGaZnO semiconductor and parylene gate insulator. The TFTs exhibited a field- effect mobility of $5cm^2V^{-1}s^{-1}$ and a current on/off ratio of $10^5$ at a relatively low operating voltage. Furthermore, the fabricated transistors showed no noticeable changes in their electrical performance for large strains of up to 50 %.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.402-407
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• 2011

The current paper describes a simpler ground-type, single-plate electrowetting configuration for droplet transport in digital microfluidics without performance degradation. The simplified fabrication process is achieved with two photolithography steps. The first step simultaneously patterns both a control electrode array and a reference electrode on a substrate. The second step patterns a dielectric layer at the top to expose the reference electrode for grounding the liquid droplet. In the experiment, a $5{\mu}m$ thick photo-imageable polyimide, with a 3.3 dielectric constant, is used as the dielectric layer. A 10 nm Teflon-AF is coated to obtain a hydrophobic surface with a high water advancing angle of $116^{\circ}$ and a small contact angle hysteresis of $5^{\circ}$. The droplet movement of 1 mM methylene blue on this simplified device is successfully demonstrated at control voltages above the required 45 V to overcome the contact angle hysteresis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1114-1119
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• 2004

The photodepositioned tungsten film by laser CVD has been carried out the taping test with scotch tape over 10 times. As a result, it exhibited strong adhesion to the under-film such as ITO and SiNx patterned on the LCD substrate. However, it was seriously attacked by alkaline solution used for removing polyimide. And a thickness of laser CVD tungsten film had a close relation to a speed of laser scanning. Also we have improved the success rate of a laser CVD repair with making two pairs of contact hole structure and decreasing laser scanning speed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.133-133
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• 2009

DC 마그네트론 스퍼터링법을 이용하여 투명 폴리이미드 기판위에 $CeO_2$가 0.5, 3.0, 4.0, 6.0wt% 도핑된 고밀도 ITO 타켓으로 증착된 ITO:Ce 박막의 구조적, 기계적 특성, 전기적 특성을 연구하여싸. ITO 박막 내에 Ce 함량이 증가할수록 결정성이 감소하였으며 $CeO_2$가 3.0wt% 도핑된 ITO타켓으로 증착한 박막의 경우 비정질구조로서 $3.96{\times}10^{-4}{\Omega}cm$의 가장 낮은 비저항 값을 관찰할 수 있었고, 기계적 내구성 또한 가장 우수하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.134-134
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• 2009

ITZO 박막은 2개의 캐소드 (DC, RF)를 이용하여 마그네트론 2원 동시 방전법에 의해 고온에서 안정한 polyimide 기판위에 상온에서 증착하고 $200^{\circ}C$에서 어닐링 하였다. XRD 측정 결과 어닐링 과정을 거친 막들은 Zn의 도입에 따란 결정성이 감소하다가 RF파워 280W에서 증착한 박막은 완전한 비정질 구조를 보였다. AFM 측정과 밴딩 테스트 결과, ITO 및 ITZO 박막들은 결정성이 감소할수록 매끄러운 표면과 낮은 저항 변화율을 보여주었다. 전기 비정항은 Zn 함량이 증가함에 따라 증가하였지만, 광학적 투과율은 $200^{\circ}C$ 어닐링 과정을 거친후의 막들에 있어서 증가됨을 보였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.258-258
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• 2011

최근 유연 기판을 이용한 태양전지 및 TFT 등 전자소자 개발에 관한 연구가 주목받고 있다. 본 연구에서는 공정 시 유리한 유리기판상 전자소자 제작 후 폴리이미드막 박리를 통한 유연전자 소자 구현을 목적으로 한다. 폴리이미드막 박리를 목적으로 희생층으로서 a-Si:H을 사용하였다. 유리기판상에 60 nm 두께의 a-Si : H을 ICP (Induced coupled plasma) 공정으로 증착한 후 a-Si : H층 상부에 30 ${\mu}m$ 두께로 폴리이미드를 코팅하여 Hot plate와 furnace에서 열처리를 거쳤다. 이후 각기 다른 파장을 갖는 레이저의 파워를 가변하며 유리 기판 후면에 조사하였다. 실험 결과 355 nm UV 레이저로 가공한 경우 희생층으로 사용 된 a-Si : H층 내에 존재하는 수소가 레이저 빛 에너지에 의해 결합이 끊어지면서 유리기판과 폴리이미드막이 분리됨을 확인하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.203-203
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• 2012

The SWCNTs network are formed on various plastic substrates such as poly(ethylene terephthalate) (PET), polyimide (PI) and soda lime glass using roll-to-roll printing and spray process. Selective patterning of carbon nanotubes film on transparent substrates was performed using a femtosecond laser. This process has many advantages because it is performed without chemicals and is easily applied to large-area patterning. It could also control the transparency and conductivity of CNT film by selective removal of CNTs. Furthermore, selective cutting of carbon nanotube using a femtosecond laser does not cause any phase change in the CNTs, as usually shown in focused ion beam irradiation of the CNTs. The patterned SWCNT films on transparent substrate can be used electrode layer for touch panels of flexible or flat panel display instead indium tin oxide (ITO) film.

• Electrical & Electronic Materials
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• v.10 no.10
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• pp.1011-1015
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• 1997

In this paper we investigated the electro-optical characteristics of amorphous (a)- twisted nematic (TN)-liquid crystal display(LCD) on polymide (PI) surfaces with different molecular structure. It was found that the domaine size of a-TN-LCD on PI with high polarization is small compared to a-TN-LCD on PI with medium polarization. It is considered that the response time of a-TN-LCd contributes to surface effect between the substrate surfaces and the LC molecules. Finally we obtained that the viewing angle of a-TN-LCD on PI surfaces increases with decreasing the domain size.