• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1009-1013
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• 2009

In this study, we have been synthesized the dielectric layer using pure organic and organic-inorganic hybrid precursor on flexible substrate for improving of the organic thin film transistors (OTFTs) and, design and fabrication of organic thin-film transistors (OTFTs) using small-molecule organic semiconductors with pentacene as the active layer with record device performance. In this work OTFT test structures fabricated on polymerized substrates were utilized to provide a convenient substrate, gate contact, and gate insulator for the processing and characterization of organic materials and their transistors. By an adhesion development between gate metal and PI substrate, a PI film was treated using $O_2$ and $N_2$ gas. The best peel strength of PI film is 109.07 gf/mm. Also, we have studied the electric characteristics of pentacene field-effect transistors with the polymer gate-dielectrics such as cyclohexane and hybrid (cyclohexane+TEOS). The transistors with cyclohexane gate-dielectric has higher field-effect mobility, $\mu_{FET}=0.84\;cm^2/v_s$, and smaller threshold voltage, $V_T=-6.8\;V$, compared with the transistor with hybrid gate-dielectric.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.316-323
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• 1995

A vital step in magnetic tape manufacturing is the surface modification of polymer substrate prior to ink application. A critical element for good adhesion of magnetic ink on polymeric substrate is the ability to join ink in cost-effective manner. Corona discharging is one of the effective methods of modifying polymer surface to improve adhesion while maintaining the desirable properties of the film itself. Surface treatment by corona which is exposure of film surface to electron or ion bombardment, rather than mere exposure to active species, like atomic oxygen or ozone, can enhance adhesion by removing contaminant, electret, roughening surface, and/or introducing reactive chemical groups. Reactive neutrals, ions, electron and photons generated during the corona treatment interact simultaneously with polymers to alter surface chemical composition, wettability, and thus film adhesion. However, it is highly recommended that extensive chains scission be avoided because it can lead to side-effect by forming sticky matter, resulting in dropouts. This paper reviews principles of surface preparation of polymer substrate by corona discharging. In addition, the experimental section provides a description of parameter optimization on corona discharging treatment and its side-effect. Experimental results are discussed in terms of surface wetting as determined by contact angle measurements.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.5
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• pp.282-288
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• 2010

Experiment on the surface characteristics of polymer films treated by atmospheric pressure plasma has been conducted. We chose the process parameters as frequency, gas flow, treatment time, and scrutinized the effects of the process parameters on the surface characteristics of polymer materials by measuring the contact angle and examining SEM. As the result, the surface characteristics highly depends on frequency, reaction gas and treatment time. In the case of PC substrate, the contact angle was changed from $83.5^{\circ}$ (before plasma treatment) to $30^{\circ}$ (after plasma treatment) at 30 kHz, CDA 0.6%, and number of repeat 7. In the case of PET substrate, the contact angle change was found from $59^{\circ}$ to $23.5^{\circ}$ at 20 kHz, CDA 0.6%, and number of repeat 7. In the case of EVA substrate, it shows from $84^{\circ}$ to $44.2^{\circ}$ at 30 kHz, CDA 0.6%, and number of repeat 7.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.510-514
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• 2003

We have studied the alignment of liquid crystals (LCs) on homeotropic polymeric surface that is scanned using an atomic force microscope (AFM) tip by optical polarizing microscopy and computer simulation. The scanned areas on one substrate are 5 $\mu\textrm{m}$ ${\times}$ 5 $\mu\textrm{m}$, 10 $\mu\textrm{m}$ ${\times}$ 10 $\mu\textrm{m}$, and 20 $\mu\textrm{m}$ ${\times}$ 20 $\mu\textrm{m}$ and this substrate is assembled to another substrate coated. with homeotropic polymer. The fabricated micro-LC cell using two substrates does not show any hysteresis and disclination lines inside the nano-rubbing areas, while changing voltage up and down. This indicates that the pretilt angle exists in the areas, thereby forming a hybrid LC configuration. From the experimental and computer simulation results, we can understand that the AFM rubbing clearly changes surface status of homeotropic alignment layer and causes the pretilt angle to an initial scanning direction.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.11
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• pp.1256-1263
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• 2012

The present study covers the ultrasonic patterning process to replicate micro-patterns on a polymer substrate. The ultrasonic patterning process uses ultrasonic waves to generate frictional heat between an ultrasonic horn and the polymer substrate, from which the surface region of the polymer substrate is softened sufficiently for the replication of micro-patterns. The ultrasonic patterning process can divided into two categories according to the direction of vibration transmission: direct patterning and indirect patterning. The direct patterning uses a patterned horn, and the ultrasonic vibration is transferred directly from the patterned horn to the substrate. On the contrary, the indirect patterning process uses a plain horn, and the micro-patterns are engraved on a mold that is located below the substrate. Thus, the micro-patterns are replicated as an indirect manner. In this study, these direct and indirect patterning processes are compared in terms of the replication characteristics. Additionally, the possibility of double-side patterning is also discussed in comparison with the conventional single-side patterning process.

• Polymer(Korea)
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• v.36 no.6
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• pp.733-738
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• 2012

The effect of glass bead and glass fiber on the enhancement of dimensional stability in poly(ethylene naphthalate) (PEN) flexible substrate for photovoltaic devices has been studied. It was found that the coefficient of thermal expansion (CTE) and the optical transmittance decreased with increasing inorganic filler content. In addition to filler contents, the size and size distribution of fillers are the other important factors to improve CTE and optical transmittance of PEN film. Our results showed that the optimum filler content was found to be about 5 wt% to enhance the dimensional stability of PEN by more than 50% with maintaining the optical transmittance over 85% for the flexible substrate.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.3
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• pp.1-9
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• 2016

The objective of this study was to exam early stages of plant growth of Euonymus fortunei 'Emerald and Gold' and Hedera japonica grown in fabric felt bag attached on vertical greenery system with the ratio of hydrophilic polymer to substrate, 0(referred as Control), 0.1, 0.2, or 0.4% (v/v), in order to effectively utilize rainfall for low maintenance. After rainfall, the increase in volumetric water content of substrate amended with the hydrophilic polymer was between 13% and 87%, compared to that in Control. During drought period, higher ratio of hydrophilic polymer to substrate slowly decreased the volumetric water content, and increased plant height, leaf length, leaf width, number of leaves, branch number, and stem diameter of both Euonymus fortunei 'Emerald and Gold' and Hedera japonica with the highest fresh and dry weights of shoots or roots under the 0.1% ratio of hydrophilic polymer.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.91-94
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• 2004

We report on the opto-electronic properties of red, green, and blue poly (fluorene) co-polymer light-emitting devices (PLEDs) fabricated on a flexible plastic substrate. The plastic substrate used has a multi-layer structure with water vapor and oxygen transmission rates of less than $10^{-5}$ g/$cm^2$-day-atm and $10^{-7}$ cc/$cm^2$-day-atm, respectively. We obtained a wide range of color gamut and a maximum emission efficiency of 0.7, 10, and 1.7 cd/A for red, green, and blue PLEDs, respectively. Finally, a simple equivalent circuit model is proposed to simulate PLED current density-voltage characteristics.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1978.10a
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• pp.207.2-207
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• 1978

Arthrobacter simplex (ATCC 6946) was cultured, induced and immobilized in acrylamide polymer. The characteristics of the immobilized whole-cell enayme were studied using hydrocortisone as the substrate. The enzyme activity was increased during the incubation of the gel particle in 0.5％ peptone media. The ennzyme reaction kinetics of the Δ'-dehydrogenase (3-oxosteroid Δ'-oxydo reductase, E. C. 1.3.99.4) foliowed the Michaelis-Menten type. Km and Vm values were different significantly after immobilization of the cell. The optimum pH and temperature were changed, too. Nitrogen sources such as casitone, peptone or tryptone were good media for the enzyme reaction. And there was no need to add cofactors of the enzyme in the pre-sence of energy sources used in the test. The effect of metal ions on the enzyme activity was insignificant. Organic solvents were used increase the substrate concentration and there was no optimum solvent concentration depending on the substrate concentration.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1125-1128
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• 2007

The laminating technique for developing flexible liquid crystal display was demonstrated by using a thin UV curable polymer film and a plastic substrate with patterned polymer wall structure. We adopted the rigid wall structure to provide a solid mechanical support for the stable molecular alignment of liquid crystals (LCs) in the device. The cover film was prepared to have an ability of aligning LC molecules by patterning a micro-groove structure using the soft-lithographic process. These two substrates can be assembled tightly by the laminating and one-step UV irradiation process because of the adhesive nature of the used UV curable polymers. Proposed method can be used to fabricate the flexible LC display with simplicity and also be applicable for a cost-effective roll-to-roll process.