• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.209-210
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• 2009

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.1
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• pp.52-60
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• 2009

A printing defect known as fluting (or waviness) of the web printed by heatset web offset printing process is one of the chronically serious problems deteriorating print quality. In this paper, fluting occurrence on uncoated papers was explored in terms of many printing conditions including drying temperature, fountain solution amount, ink supply, and press configurations. For this purpose, fluting on prints from real press runs was appraised in a quantitative manner. As results, ink supply was a distinctive factor for fluting such that the lower ink amount, the milder fluting. However increase in fountain solution seemed to make fluting severer while the effect of drying temperature was inconsistent for each paper. This result might indicate variable drying requirements for each paper. Thereby it was suggested that the optimum drying conditions related to the printabilities of each paper need to be established to minimize fluting potential. A press with short dryer and drastic cooling unit produced higher fluting. Suggestions for future work were given along with interpretation for the results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.8
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• pp.709-714
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• 2014

Reverse-offset printing is one of the technologies that can be used for patterning fine features of the order of a few micrometers for printed electronics. In reverse-offset printing, a coated ink film is transferred to a blanket made of elastomer-like poly-dimethylsiloxane. Then, the blanket is impressed onto a clich$\acute{e}$ that has intaglio patterns. The blanket is deformed by penetrating the intaglio of the clich$\acute{e}$ according to the printing pressure. Excessive deformation of the blanket can cause printing defects upon touching the bottom of the intaglio pattern, especially in large patterns. In this paper, we modelled the deformation of the blanket using the finite element method. Considering the actual printing parameters, a condition for fabricating a clich$\acute{e}$ is proposed to prevent defects by the deformation of the blanket.

• Journal of the Korean Graphic Arts Communication Society
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• v.28 no.2
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• pp.69-85
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• 2010

Currently, environmental contaminants that can cause Aromatic types of hydrocarbons, less than 1% made of Aromatic Free kind of used products, soybean oil products with linseed oil with the products, rice products using a wide range of environmentally ecological ink since 2000 is released quickly. All materials used in printed material, if the green is the best way to print the composite materials in industrial applications, because each process on the print quality and productivity, there can be many differences in this experiment because it accounts for a large proportion in the print general ink in the ink section and the International color standards(ISO2846-1:2006) certified ecological ink were compared. Therefore, in this paper has the ink released from the same company, each common general ink and ecological ink in the same condition which results were focused on whether the emerging international color standard(ISO 2846-1:2006) recognized for environmentally ecological ink printed color reproduction of the actual offset(color reproduction) how conformity to ISO 12647-2 standard color on the basis of the offset would check Color Reproduction. Based on the results of the experiments of this study, given the ecological ink coated paper, uncoated paper both color difference and the gamut of the ISO 12647-2 standard is suitable for ecological ink, the ink's color gamut reproduction, even more than existing international standards, there is no confirmed that the correct color reproduction possible. Using environmentally ecological ink industries is expected to respond to environmental policy.

• Journal of the Korean Graphic Arts Communication Society
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• v.14 no.1
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• pp.31-45
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• 1996

For the purpose of study on the printability of domestic art papers, the physical properties of domestic coated paper for offset printing were investigated. 25 kinds of sample papers were prepared and were examined in accordance with KS and TAPPI standard testing method i.e., basis weight, density, opacity, gloss, roughness, smoothness, brightness, and K&N absorption. IGT printability tester was used to obtain the printability parameters, such as maximum ink requirement of paper Y, limiting printing density D print through, and density smoothness constant m value.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.60-69
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• 2008

The principal reasons for applying a pigment coating to paper are to improve appearance and printability. The pigment coating provides a surface that is more uniform and more receptive to printing ink than are the uncoated fibers and, in turn, both facilitates the printing process and enhances the graphic reproduction. The improvement in print quality is readily apparent, especially in image areas or when multiple colors are involved. Although pigment coating of paper is to improve the printability, coated paper is not completely free from printing defects. Actually there are a number printing defects that are observed only with the coated papers. Among the printing defects that are commonly observed for coated papers, print mottle during multi-color offset printing is one of the most concerned defects, and it appears not only on solid tone area but also half dot print area. There are four main causes of print mottle ranging from printing inks, dampening solution, paper, and printing press or its operation. These indicates that almost every factors associated with lithographic printing can cause print mottle. Among these variation of paper quality influences most significantly on print mottle problems in multicolor offset printing, and this indicates that paper is most often to be blamed for its product deficiency as far as print mottle problems are concerned. Furthermore, most of the print mottle problems associated with paper is observed when coated papers are printed. Uncoated papers rarely show mottling problems. This indicates that print mottle is the most serious quality problems of coated paper products. Overcoming the print mottle is becoming more difficult because the operating speeds of coating and printing machines are increasing, coating weights are decreasing, and the demands on high-quality printing are increasing. Print mottle in offset printing is caused by (a) nonuniform back trap of ink caused by a nonuniform rate of ink drying, referred as "back trap mottle, and (b) nonuniform absorption of the dampening solution. Furthermore, both forms of print mottle have some relationship to the structure of the coated layer. The surest way of eliminating ink mottling is to eliminate unevenness in the base paper. Coating solutions, often easier to put into practice, should, however, be considered. In this paper the principal factors influencing print mottle of coated papers will be discussed. Especially the importance of base paper roughness, binder migration, even consolidation of coating layers, control of the drying rate, types of binders, etc. will be described.

• Journal of the Korean Graphic Arts Communication Society
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• v.25 no.1
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• pp.1-9
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• 2007

• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.2
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• pp.15-32
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• 2011

In printing, managing color means that how closely its color reproducts and printing supplier meets customers' requirements. When applying device profiles, it depends on properties of the devices. But color management of domestic digital prints is accomplished more scientifically and objectively than any other printing. According to this paper addresses a method of evaluating between proof prints and offset prints which are produced by identical date on the field. We evaluate two cases normal proof prints and domestic offset prints based on standardized color data analysis and subjective data analysis. We gathered objective data by measuring solid density, $CIEL^*a^*b^*$ and ${\Delta}E^{*_}{ab}$. Furthermore, we evaluated the offset prints and proof prints through human eyes to decide the ranking.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.10
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• pp.1146-1152
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• 2011

Ink transfer process is very important to determine quality of printed pattern, therefore its mechanism should be understood to control printing quality. Although there have been many attempts to understand ink transfer mechanism by numerical simulation and experimental studies, their model was too much simple to model realistic printing process and our understanding is not enough yet. In this paper we designed ink transfer visualization system to present flow visualization of ink transfer process for gravure offset printing. We considered rotational effect of blanket roll which is related with printing speed and used non-Newtonian fluid as working fluid such as Ag paste. For printing unit, cantilever-type blanket roll is used for convenient visualization of ink transfer. Serial images were captured continuously by using high-speed CMOS camera and long range microscope. We investigated the effects of various design parameters such as printing speed and pattern angle on the ink transfer process. We found more stretched ink filament for non-Newtonian fluid than Newtonian fluid. As increasing printing speed, length of stretched ink filament and height of break-up point are also increased. We also compared ink transfer process between CD and MD pattern and its relationship with ink transfer mechanism.

• Proceedings of the Korean Printing Society Conference
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• 1998.10a
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• pp.7-15
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• 1998