• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.583-584
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• 2006

Printing technology has begun to get into the spotlight in many ways due to the low cost effectiveness to existent semi-conductor process. It also has very useful application areas, not only paper printing but also patterning for LCD color tilter, Photovoltaic patterning, RFID antenna, OLED, and so on. In this study, an apparatus of gravure offset printing was developed for fine line width printing. The pattern was composed of $20{\mu}m$ size of continuous lines of which pitch size was $40{\mu}m$. The printed pattern shows that it is possible to make around $20{\mu}m$ line-width printing pattern. The roll-to-roll printing system for fine line-width printing based on primary experiment is presented. For testing of multi-layer printing, the system was designed to be capable of printing two different materials from each printing unit using gravure-offset printing method and have a function of alignment of two printed materials.

• Journal of the Korean Graphic Arts Communication Society
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• v.30 no.2
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• pp.1-12
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• 2012

In this experiment, we have manufactured thermal-curable silver pastes for direct printing. And to enhance conductivity, printability, adhesion and hardness during polymer direct-gravure prints, we have manufactured Ag pastes by adding variety of filter contents. Then we have investigated characteristics of rheology in paste according to the gravure printability and the properties of printed conductive patterns. Depending on a variety of Ag powder, there was a big difference in sharpness of printed pattern. And also by the use of carbon, there was a big difference in amount of solvent used, conductivity and in hardness. We could improve doctoring and the sharpness of a pattern by adding Ag paste in carbon particle, but as we have used nano-sized particle, there was an increase in the amount of solvent used and also we have found out that it gives a bad effect as adhesive and hardness becomes weaker. Even though Ag particle has the same spherical shape, the surface treatments could differ from one another. And by the appropriate choice and with the suitable combination of Ag powder, excellent printability and conductivity could be obtained.

• Transactions on Electrical and Electronic Materials
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• v.6 no.2
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• pp.78-84
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• 2005

Standard crystalline solar cells are generally fabricated with the front grid pattern of silver paste contact. We have reported a detailed theoretical analysis of the proposed segmented cross grid line pattern in this paper. This work was carried out for the optimization of spacing and width of grid finger, main busbar and sub-busbar. The overall electrical and optical losses due to front contact were brought down to $10\%$ or even less as compared to the usual loss of $15\%$ or more in the conventional screen printed silver paste technology by choosing proper grid pattern and optimizing the grid parameters. The total normalized power loss for segmented mesh grid with plated metal contact was also observed and the total power loss could be brought down to $10.04\%$ unlike $11.57\%$ in the case of continuous grid and plated contact. This paper is able to outline the limitations of conventional screen printed contact.

• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.55-60
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• 2010

Ink transfer process from the printing roll to the moving web was investigated using a CFD technique for the application in R2R printed electronics. In line with the requirement that the web handling speed needs to be increased further for the cost competitiveness, the effects of web moving velocity with relatively complex roll patterns were analyzed. To make the present analysis more realistic, the numerical geometry and the ink properties were selected to match those of the real printing production system. Our numerical results showed that both web handling speed and complex printing-roll patterns influenced the shape of the transferred ink. As the web moving speed approaches towards 30mpm, a significant distortion of the shape of the transferred ink occurred. In the range of pattern width smaller than 100 microns, a phase distortion was also found to occur in all the printing-roll patterns considered in the present work but the ratio of the phase distortion to the line width gets smaller as the width becomes smaller. Thus, the web handling speed and the shape of printing-roll pattern will be important elements for the better printing quality under 100 micron line width range.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.6
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• pp.945-962
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• 2022

This study examines the use of traditional patterns by new Hanbok brands. A Saekdong print pattern based on previous research was developed and applied to clothing designs. A total of 488 images of printed products from the seven new Hanbok brands and 219 images from the collections of the National Folk Museum of Korea were analyzed. Traditional patterns accounted for 47.4% of the total printed products of the new Hanbok designs, with the following ratio of use, in descending order: flower patterns, traditional paintings, animals, geometrical designs, Dancheong, text and others, Jogakbo, and Saekdong. Saekdong was found in three brand products, and the color or shape was modified. To develop the Saekdong image, five colors - red, yellow, blue, white, and green - were selected. The ratio of use for each color and the width of each color were determined with reference to previous studies. The average color value was determined through color analysis of the Saekdong collections. A total of seven items were designed for the print pattern, and four items were added for coordination to consist of four styles. This study aims to use the results of this analysis to provide insights into product development using traditional patterns.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.21-27
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• 2022

Flexible pressure sensor was developed using low-cost conductive graphite as printed electronics. Flexible pressure sensors are attracting attention as materials to be used in future industries such as medical, games, and AI. As a result of evaluating various electromechanical properties of the printed electrode for flexible pressure sensors, it showed a constant resistance change rate in a maximum tensile rate of 20%, 30° tension/bending, and a simple pulse test. A more appropriate matrix pattern was designed by simulating the electrodes for which this verification was completed. Utilizing the Serpentine pattern, we utilized a process that allows simultaneous fabrication and encapsulation of the matrix pattern. One side of the printed graphite electrode was O₂ plasma surface treated to increase adhesive strength, rotated 90 times, and two electrodes were made into one through a lamination process. As a result of pasting the matrix pattern prepared in this way to the wrist pulse position of the human body and proceeding with the actual measurement, a constant rate of resistance change was shown regardless of gender.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.578-583
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• 2013

The lighting devices using organic light emitting diodes (OLEDs) are actively researched because of the various advantages such as high power efficiency and 2-dimensitonal lighting emitting. To commercialize those OLED lighting devices, the manufacturing cost must be downed to comparable price with conventional light sources. Here, we demonstrate a reverse gravure-offset or gravure off-set printed metal electrode for the auxiliary electrode for OLED lighting devices. For the fabricated OLED's auxiliary electrode, we used Ag nano-paste and printed metal grid structure with a line width and spacing of several ten and hundred micrometer by using gravure-offset printing. In the end the printing metal grid pattern are successfully achieved by optimization of various experimental conditions such as printing pressure, printing speed and printing delay time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.171-171
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• 2009

We have investigated the impact of coffee ring effect on the inkjet-printed $Al_2O_3$ thick films. In a single solvent system such as Dimethylformamide, the coffee-ring-pattern has appeared on the edge of sessile drop after evaporation. The peak-to-valley height difference in $Al_2O_3$ coffee ring is over 2um. This non-uniform deposition of $Al_2O_3$ over the surface leads to sever surface roughness of the inkjet-printed films. However, we have manipulated our printing parameters to improve the surface roughness and the packing density of the printed $Al_2O_3$ films. Our inkjet-printed $Al_2O_3$ films show 10 times smoother surface than the initially printed sample's surface. Also the packing density of the printed Ah03 film becomes 70% of high packed $Al_2O_3$. In this presentation, we would like to present the key process parameters of the inkjet printing process to overcome the genetic coffee ring problem.

• Journal of Fashion Business
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• v.13 no.2
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• pp.115-122
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• 2009

Marbling dyeing technique shows beautiful flowing pattern because the pattern is transferred to the medium by the pigments floating onto the viscous solution base. However, this marbling pattern does not have any reproducibility and the result of accidental pattern formation. Marbling process contains many complicated procedures such as making marbling base, mordanting the medium, and bubble removal with size limitation. Computer changed the many aspects in textile design and digital technique is used in many design production. However, it is impossible to produce marbling pattern with digital drawing. In this research, the digital textile design starting from marbling pattern was developed for digital textile printing. Marbling was done to produce the initial motifs and scanned. Several marbling media such as silk, polyester, and paper were used. Photoshop was used to process and develop textile design based on these marbling motifs. One repeat was developed and various colorways were tried. The developed textile design were printed using DTP.

• Textile Coloration and Finishing
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• v.23 no.3
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• pp.169-178
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• 2011

The purpose of this study is to develop eco-printing method using natural dyes combined with chitosan treatment to impart various pattern effect on cotton fabric. It was examined whether tone-on-tone pattern effects could be produced by screen printing with chitosan paste and subsequently dip-dyed in natural dye bath. For polychromic colorants, fabrics were pre-mordanted and then screen printed with chitosan, while only chitosan printing treatment was applied for monochromic colorants. Color, dye uptake, washing, light and rubbing fastnesses of printed fabrics were measured in relation to the presence of chitosan printing. Pre-mordanting and chitosan printing treatment were applied to such polychromic colorants as madder, sappanwood, onion and cochineal. Also, printing pattern formation on fabrics was evaluated by differences in dye uptake and color. The results suggested that madder, onion and cochineal were effective on pattern formation. Regarding sappanwood, since dye uptake was increased only by pre-mordanting without chitosan printing treatment, there was little color difference and thus patterns were not clearly distinguished. Chitosan printing treatment tended to increase washing, light and rubbing fastnesses of dyed fabrics with polychromic colorants. Chitosan printing treatment was applied to monochromic colorants such as chlorophyll, gardenia and indigo and the effect of printing formation was examined according to the difference in dye uptake. Among monochromic dyes tried, chlorophyll was effective and chitosan printing improved washing and light fastnesses.