• Polymer(Korea)
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• v.36 no.4
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• pp.531-535
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• 2012

Conductive polyaniline (PANI) nanofibers in UV-curable resin were used for a transparent conductive film. The emeraldine-salt PANI (ES-PANI) nanofibers were prepared by chemical oxidation polymerization of aniline, which could be changed into emeraldine-base PANI by dedoping. EB-PANI nanofibers as a precursor for conductive fillers were thereby transformed into re-dpoed PANI (rES-PANI) by dodecylbenzenesulfonic acid in the UV-curable resin solution. rES-PANI nanofibers have high conductivity and long-term stability in the solution without a defect of nanostructure. The resulting conductive resin solution was proved to be highly stable where no precipitation of rES-PANI fillers was observed over a period of 3 months. The transparent film was spin-casted on a poly(methyl methacrylate) sheet of thickness ca. $5{\mu}m$. A surface resistance of $6.5{\times}10^8{\Omega}/sq$ and transmittance at 550 nm of 91.1% were obtained for the film prepared with a concentration of 1.4 wt% rES-PANI nanofibers in the solution. This transformation process of rES-PANI from ES-PANI by dedoping-redoping can be an alternative method for the preparation of an antistatic protection film with controllable surface resistance and optical transparencies with the PANI concentration in UV-curable solution.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.569-573
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• 2014

We demonstrate a low-cost, superbly efficient way of etching for the nano-, and micro-sized pyramid patterns on (100)-oriented Si wafer surfaces for use as a patterned master. We show a way of producing functional optical films for the viewing angle direction brightness-enhancement of Lambertian LED (light emitting diode)/OLED (organic light emitting diode) planar lighting applications. An optimally formulated KOH (Potassium hydroxide) wet etching process enabled random-positioned, and random size-distributed (within a certain size range) pyramid patterns to be developed over the entire (100) silicon wafer substrates up to 8" and a simple replication process of master patterns onto the PC (poly-carbonate) and PMMA (poly-methyl methacrylate) films were performed. Haze ratio values were measured for several film samples exhibiting excellent values over 90% suitable for LED/OLED lighting purposes. Brightness was also improved by 13~14% toward the viewing angle direction. Computational simulations using LightTools$^{TM}$ were also carried out and turned out to be in strong agreement with experimental data. Finally, we could check the feasibility of fabricating low-cost, large area, high performance optical films for commercialization.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.320-324
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• 2015

Optimization of the fabrication process of NiO-yttrium doped barium zirconate (BZY) composite anode substrates using tape-casting for high performance thin-film protonic ceramic fuel cells (PCFCs) is investigated. The anode substrate is composed of a tens of microns-thick anode functional layer laminated over a porous anode substrate. The macro-pore structure of the anode support is induced by micron-scale polymethyl methacrylate (PMMA) pore formers. Thermal gravity analysis (TGA) and a dilatometer are used to determine the polymeric additive burn-out and sintering temperatures. Crystallinity and microstructure of the tape-cast NiO-BZY anode are analyzed after the sintering.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.1
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• pp.24-29
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• 2005

Silicon nitride cantilevers integrated with silicon heaters and piezoelectric sensors were developed for the scanning probe microscope (SPM) based data storage application. These nitride cantilevers are expected to have better mechanical stability and uniformity of initial bending than the previously developed silicon cantilevers. Data bits of 40 nm in diameter were recorded on PMMA film and the sensitivity of the piezoelectric sensor was 0.615 fC/nm, meaning that indentations less than 20 nm in depth can be detected. For high speed operation, $128{\times}128$ cantilever array was developed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.333-338
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• 2003

Nano-imprint lithography(NIL) is a polymer embossing technique, capable of transferring nano-scale patterns onto a thin film of thermoplastics such as polymethyl methacrylate(PMMA) using this parallel process. Feature size down 10 nm have been demonstrated. In NIL, the pattern is formed by displacing polymer material, which can be squeeze flow of a viscous liquid. Due to the size of the pattern, a thorough understood of the process through experiments may be very different. Therefore we nead to resort to numerical simulation on the embossing process. Generally, there are two ways of numerical simulation on nano-scale flow, namely top-down and bottom-up approach. Top-down approach is a way to simulate the flow assuming that polymer is a continuum. On the contrary, in the bottom-up approach, simulation is peformed using molecular dynamics(MD). However, as latter method is not feasible yet. we chose the top-down approach. For the numerical analysis, two dimensional moving grid was used since the moving grid can predict the flow front. Effects of surface tension as well as the slip at the boundary were also considered.

• Journal of Environmental Science International
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• v.17 no.11
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• pp.1235-1241
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• 2008

Membrane separation is extensively used for water/wastewater treatment because of its efficiency separation processes. However, particles in the feed water can deposit and accumulate on the membrane surface to created cake layer. As a consequence, the selectivity of the membrane and flux through the membrane are decreased, which is called fouling/blocking phenomenon. In order to solve fouling problem, we developed a novel membrane named Carbon Whisker Membrane (CWM) which contains vapor-grown carbon fibers/whiskers on the surface of the membrane and a layer of carbon film coated on the ceramic substrate. We firstly employed polymethyl methacrylate (PMMA) as a testing material to investigate the fouling mechanism. The results suggested that Carbon Whiskers on the surface of the membrane can prevent the directly contact between the membrane body and particles so that the fouling/blocking could not occurred easily compared to the membrane without carbon whiskers. We also researched the relationship with the diameter, density of carbon whisker on the membrane surface and total flux of solutions. Finally, we will be able to control the diameter and density of carbon whiskers on the membrane and existence of carbon whiskers on the membrane, it is important factor, might be prevent fouling/blocking in the water treatment.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1336_1337
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• 2009

본 논문에서는 유기 박막 트랜지스터의 전극을 잉크젯 프린팅과 스크린 프린팅 방법을 이용하여 유기 박막 트랜지스터를 제작하였다. 전극으로 PEDOT:PSS와 Ag 잉크를 사용하였고, 게이트 절연막으로 polymethyl methacrylate (PMMA)와 poly(4-vinylphenol) (PVP)를 사용하였다. 유기물 활성층으로 pentacene을 진공 증착하였다. 잉크젯 프린팅 방법을 이용하여 제작한 유기 박막 트랜지스터는 전계이동도 (${\mu}_{FET}$) $0.068\;cm^2$/Vs, 문턱전압 ($V_{th}$) -15 V, 전류 점멸비 ($I_{on}/I_{off}$ current ratio) >$10^4$의 전기적 특성을 보였고, 스크린 인쇄 방법을 이용하여 제작한 유기 박막 트랜지스터는 전계이동도 (${\mu}_{FET}$) $0.016\;cm^2$/Vs, 문턱전압 ($V_{th}$) 6 V, 전류 점멸비 ($I_{on}/I_{off}$ current ratio) >$10^4$의 전기적 특성을 보였다. 이를 통하여 프린팅 방법을 이용한 유기 박막 트랜지스터 단일 소자 및 유기 전자 회로 제작의 가능성을 확인 하였다.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.136-141
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• 2007

This paper introduces an artificial neuron which is a nano composite continuous sensor. The continuous nano sensor is fabricated as a thin and narrow polymer film sensor that is made of carbon nanotubes composites with a PMMA or a silicone matrix. The sensor can be embedded onto a structure like a neuron in a human body and it can detect deteriorations of the structure. The electrochemical impedance and dynamic strain response of the neuron change due to deterioration of the structure where the sensor is located. A network of the long nano sensor can form a structural neural system to provide large area coverage and an assurance of the operational health of a structure without the need for actuators and complex wave propagation analyses that are used with other methods. The artificial neuron is expected to effectively detect damage in large complex structures including composite helicopter blades and composite aircraft and vehicles.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.278-281
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• 1999

The purpose of this study is to investigate the effect of the scattered x-rays on the subject contrast and image sharpness for various tube voltages. For the purpose, we measured the scatter-to-primary ratio(SPR) for the tube voltages f 50 to 100kV and obtained the tube voltage dependence of the subject contrast of an aluminum plate in a polymethyl methacrylate(PMMA) phantom. Furthermore, the overall modulation transfer functions(MTFs), which consist of MTFs of a screen-film system and scatter FTMs, were obtained for tube voltages of 50 to 100 kV. The subject contrast decreased with the tube voltage due to that the SPR increased with the tube voltage and that the difference in effective linear attenuation coefficients between the object and its surroundings decreased with the tube voltage. The maximum frequency of the overall MTF decreased from about 2 mm$\^$-1/ to 1 mm$\^$-1/ with the tube voltage increasing from 50 to 100 kV.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.22-25
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• 2005

In this research, a wafar-level transfer method of cantilever array on a conventional CMOS circuit has been developed for high density probe-based data storage. The transferred cantilevers were silicon nitride ($Si_3N_4$) cantilevers integrated with poly silicon heaters and piezoelectric sensors, called thermo-piezoelectric $Si_3N_4$ cantilevers. In this process, we did not use a SOI wafer but a conventional p-type wafer for the fabrication of the thermo-piezoelectric $Si_3N_4$ cantilever arrays. Furthermore, we have developed a very simple transfer process, requiring only one step of cantilever transfer process for the integration of the CMOS wafer and cantilevers. Using this process, we have fabricated a single thermo-piezoelectric $Si_3N_4$ cantilever, and recorded 65nm data bits on a PMMA film and confirmed a charge signal at 5nm of cantilever deflection. And we have successfully applied this method to transfer 34 by 34 thermo-piezoelectric $Si_3N_4$ cantilever arrays on a CMOS wafer. We obtained reading signals from one of the cantilevers.