• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.1 s.256
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• pp.51-61
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• 2007

This paper presents numerical and theoretical studies of acoustic wave interactions in slightly compressible liquids within piezoelectrically driven inkjet print heads. The interconnected flow channels may cause jet crosstalk, resulting in poor printing quality. It should be reduced by modifying the channel structure with the acoustic wave interactions considered. Compressible gas flow driven by the sudden movement of a top wall in the channel is calculated using Flow3D and is validated with the narrow gap theory. Limited compressibility model of the Flow3D is employed to calculate pressure waves of slightly compressible ink flow. It is found that reducing restrictor width can damp out the jet crosstalk by inhibiting the pressure wave propagation. The degree of crosstalk has been quantified using the maximum values of cross-correlations between neighboring channels and a critical channel dimension for acceptable crosstalk has been proposed. This finding is verified by drop visualization experiments using silicon-micromachined piezo inkjet print heads that are fabricated by our group.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.154-154
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• 2006

Samsung Electro Mechanics ink jet has developed ultra high resolution alignment system. The alignment system has been developed for repeatable printing of conductive ink. The resolution of alignment system is 0.5um and the velocity of printing working plate is 1.5m/s. So far repeated printing results included sintering process have over 30um of drop mislocation data. In order to improve line thickness and conductivity of metal line, we need to develop the higher mechanical accurate align system. On the demand, this developed align system has under $1{\sim}2{\mu}m$ mispositioning performance and can measure of mechanical accuracy of inkjet printer, as well as the straightness of jetted drop from inkjet head. There is no kinds limit of substrate and ink to use SEM alignment system. By using this alignment system, we progress two experiment of reiterate printing drop and making conductive line on the glass and photo paper. Optical microscope and 3D profiler has been used for measurement of printed ink.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.1
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• pp.35-45
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• 2000

Recently, as the prepress mainstream is changed to the digital workflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. However, most of the digital proofing devices have lower resolution than analog proofing systems and differ with actual color presses in the color gamuts. Therefore, proper color compensations are needed for digital color proofing in order to match colors between the proofs and the press sheets. This study shows the application method of Look-up Table to the digital color proofer of Rainbow, the analog proofer of Matchprint-II, and an actual offset press is effective on the color compensations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.203-203
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• 2009

Low temperature annealing for oxide TFTs including IGZO on PI substrate is the essential process to fabricate flexible display devices, since low heat-resistance on PI and PEN substrates limits the temperature range. Laser annealing is one of the promising candidates for low temperature process, and it has been used for various application in semiconductor and LCD fabrication. We irradiated laser to solution-based IGZO thin films on PI substrate were irradiated to laser beam, and investigated laser damage of PI layer. Based on transmittance analysis, wavelength(532nm) and scan speed(1000mm/s) is the optimized condition for laser irradiation about ink-Jet printed oxide TFTs on PI substrates.

• Journal of the Korean Society of Visualization
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• v.15 no.2
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• pp.21-25
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• 2017

If a liquid droplet evaporates on a solid substrate, when it completely dries, it leaves a peculiar pattern, which depends on the composition of the liquid. Not only a single component liquid but also complex liquids are studied for a different purpose. In particular, a binary mixture droplet has been widely studied and used for an ink-jet printing technology. In this study, we focus on investigating to visualize the internal flow field of an ethanol-water mixture by varying a concentration ratio between two liquids. We measure the in-plane velocity vector fields and vorticities. We believe that this fundamental study about the internal flow field provides a basic idea to understand the dried pattern of the binary mixture droplet.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.215-219
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• 2004

We reported two new techniques of barrier rib formation that are applicable to a variety of structures for high-efficiency PDPs suitable for mass-production [1]. These two methods are mold replication and direct glass sculpting. Especial progress has since been made in improving these methods to be more suitable for high-efficiency PDPs with the DelTA cell structure. This paper reports photolithographic fabrication methods for the masters used in mold replication. The masters for more complex barrier rib forms are easier to make with these methods. The paper also reports a process that combines the direct glass sculpting method with an ink-jet printing method of electrode formation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.61-67
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• 2004

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field-assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time and magnetic abrasive size. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• Proceedings of the Korean Printing Society Conference
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• 2000.12b
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• pp.17-28
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• 2000

Recently, as the prepress mainstream is changed to the digital workflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. However, most of the digital proofing devices have lower resolutions than analog proofing systems and differ with actual color presses in the color gamuts. Therefore, proper color compensations are needed for digital color proofing in order to match color between the proofs and the press sheets. In this paper, we used 3-dimensional look-up table(LUT) and tetrahedral interpolation method for the color space conversion between the device independent color space(CIEXYZ or Lab) and the device dependent color space(CMY) to reduce the color differences between the original copy and digital color proofs and the press sheets.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.285-292
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• 2016

Three-dimensional (3D) printing is driving major innovation in various areas including engineering, manufacturing, art, education and biosciences such as biochemical engineering, tissue engineering and regenerative medicine. Recent advances have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional tissues. Compared with non-biological printing, 3D bioprinting involves additional complexities which require the integration of technologies from the fields of biochemical engineering, biomaterial sciences, cell biology, physics, pharmaceutics and medical science.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1771-1773
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• 2007

Surface modification of the gate dielectric has a strong influence on the performance of printed transistors. The surface modification occurs between the gate dielectric and semiconductor. The printed transistor with evaporated vanadium pentoxide ($V_2O_5$) modification exhibits a mobility of $0.2cm^2\;V^{-1}\;s{-1}$ and a subthreshold slope of 1.47 V/decade.