• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.7 s.250
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• pp.700-706
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• 2006

This study presents a numerical procedure to optimize the shape of dimple surface to enhance turbulent heat transfer in a rectangular channel. The response surface based optimization method is used as an optimization technique with Reynolds-averaged Wavier-Stokes analysis of fluid flow and heat transfer with shear stress transport (SST) turbulence model. The dimple depth-to-dimple print diameter ratio, channel height-to-dimple print diameter ratio, and dimple print diameter-to-pitch ratio are chosen as design variables. The objective function is defined as a linear combination of heat transfer related term and friction loss related term with a weighting factor. full factorial method is used to determine the training points as a mean of design of experiment. The optimum shape shows remarkable performance in comparison with a reference shape.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.159-162
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• 2007

This study presents a numerical procedure to optimize the shape of a staggered dimpled surface to enhance the turbulent heat transfer in a rectangular channel. A optimization technique based on neural network is used with Reynolds-averaged Navier-Stakes analysis of the fluid flow and heat transfer with Shear Stress Transport turbulence model. The dimple depth-to-dimple print diameter ratio, channel height-to-dimple print diameter ratio, and dimple print diameter-to-pitch ratio are chosen as design variables. The objective function is defined as a linear combination of terms related to heat transfer and friction loss with a weighting factor. Latin Hypercube Sampling is used to determine the training points as a mean of the Design of Experiment. Optimal values of the design variables were obtained in a range of the weighting factor.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.285-288
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• 2004

This study presents a numerical procedure to optimize the shape of dimple surface to enhance turbulent heat transfer in rectangular channel. The response surface based optimization method is used as an optimization technique with Reynolds-averaged Wavier-Stokes analysis of fluid flow and heat transfer with shear stress transport (SST) turbulence model. The dimple depth-to -dimple print diameter ratio, channel height- to- dimple print diameter ratio. and dimple print diameter-to-pitch ratio are chosen as design variables. The objective function is defined as a linear combination of heat transfer coefficient and friction drag coefficient with a weighting factor. Full factorial method is used to determine the training points as a mean of design of experiment.

• The KSFM Journal of Fluid Machinery
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• v.10 no.3 s.42
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• pp.39-46
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• 2007

This study presents a numerical procedure to optimize the shape of staggered dimple surface to enhance turbulent heat transfer in a rectangular channel. The RBNN method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer with shear stress transport (SST) turbulence model. The dimple depth-to-dimple print diameter (d/D), channel height-to-dimple print diameter ratio (H/D), and dimple print diameter-to-pitch ratio (D/S) are chosen as design variables. The objective function is defined as a linear combination of heat transfer related term and friction loss related term with a weighting factor. Latin Hypercube Sampling (LHS) is used to determine the training points as a mean of the design of experiment. The optimum shape shows remarkable performance in comparison with a reference shape.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.2 s.115
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• pp.16-21
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• 2006

Uneven ink transfer of a print can be traced to several causes such as an incomplete contact between the paper surface and ink film, a coarse pattern of a continuous ink film after transfer, uneven absorption, etc. Uneven ink transfer was studied in this points by the Tollenaar. Uneven distributions of printed density are reflected in low ${\ulcorner}m{\lrcorner}$ values of the print. Tollenaar's smoothness coefficient ${\ulcorner}m{\lrcorner}$ value was important factor that deciding printed quality which was easily obtain by densitometry. Limiting print density $D_{\infty}$ that obtained Tollenaar's formulation working as a influence factor at the printed quality. In this study, we obtained limiting print density $D_{\infty}$ and smoothness coefficient ${\ulcorner}m{\lrcorner}$ value of domestic newspapers and foreign newspapers. And we analyzed about properties of the newspaper. The result of this study, smoothness coefficient ${\ulcorner}m{\lrcorner}$ value and limiting print density $D_{\infty}$ showed the good results in the low porosity and low roughness newspaper. Datum which obtained by this study was used as printability factor for the quality control and improvement of domestic newspaper and wished to apply as a basic data for the domestic newspaper quality.

• Journal of the Korean Graphic Arts Communication Society
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• v.23 no.2
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• pp.59-75
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• 2005

In gravure printing, the amount of ink from cells has a great effect on the qualities of final printed products. And printability of final products is determined by every kinds variables. Ink transfer process is not verified scientifically because gravure cell is of small size and print speed is rapid. Therefore in order to study of ink transfer mechanism, this study is using the Computational Fluid Dynamics Evaluation. Polyflow 3-10 simulation software is used for considering of non-Newtonian flow. Among the various factors, this study have dealt with gravure cell types used computer simulation in order to define distinctive features in ink flow and transfer. The results of simulation, it defined the distribution of pressure, speed, stream function, viscosity, shear rate during the gravure printing. It is fined out the difficulties and characteristics according to the shape of cell types. Through this study, the condition of gravure printing is depending on the print condition and characteristic of cells.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.3
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• pp.53-58
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• 2002

This paper was performed to investigate the effect of pore structure on ink residual behavior. To prepare different coating structures as substrates against inks, fine, medium and coarse calcium carbonate were used in the coating color. It is well known ink properties can affect to print qualities. After printing on the coated paper, ink layer can consider as third structure addition to paper and coating layer. To compare effect of ink properties on the surface structure and print qualities, several properties of ink were also adopted as raw material. Particle size of pigment effect on gloss evaluation of coated paper increased with calendering. It was shown that ink transfer rate increased as surface of the sample was smooth. The ink contained low viscosity resin evaluated more print gloss. Finer pigment particle size, smaller pore size and higher porosity. Pore volume of coated paper was slightly decreased with printing as the coating was prepared with the finest particle size. However, it founded that ink resin could not affect on pore volume and distribution of printed paper

• Journal of the Korean Graphic Arts Communication Society
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• v.15 no.1
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• pp.17-30
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• 1997

In this work, we have investigated the printability such as print through and str-off of domestic newspapers. Nine kinds of domestic newspapers Hansol, Deahan, Sinho, Hanla and Sepung, were tested by IGT printability tester, and studied using maximum ink requirement method. We obtained the datum of printability parameters such as maximum ink requirment of paper Ymax, printing density D, print through, set-off and gloss. The results of this test showed that a choice of the fillers on the newspaper had an effect on print through, set-off and density of newspapers in the maximum ink transfer point.

• Journal of the Korean Graphic Arts Communication Society
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• v.19 no.1
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• pp.42-54
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• 2001

The combination of a silicone surfaced plate and high viscosity ink produced a waterless printing system that worked well, but had limitation. The limitation was that this system was restricted to relatively short run lengths. In the waterless printing process, the press tended to heat up rapidly. Heat in turn, broke down the resins in the inks, causing them to become more fluid. When the ink is heated, the viscosity will drop, the ink will become too liquid and the plate will no longer be able to resist it. The ink will adhere to the non-print portions of the plate, and will print as a very fine mist or speckle pattern in the non-image area. On the other hand, when the ink gets too cold, viscosity will increase until ink transfer is impeded. This study carried otu to investigate the effect of temperature variations of the inks on the print quality in waterless lithography and to examine the adaptability of waterless lithography to conventional offset press without cooling system.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.1 s.113
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• pp.27-33
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• 2006

Newsprint is quantitatively the most important printing paper. The demands for its printability are continuously increasing. It is well known that the relationship between the physically tested paper properties and newspaper printability is unsatisfactory. In order to improve the printing quality of Korean newsprint, the printability coefficients such as maximum ink requirement(Ymax), print through were investigated. Kinds of newspapers and black printing ink were tested by IGT printability tester. Experiment condition of IGT printability tester was 14 steps between $0.2{\sim}2.8g/m^2$ of ink requirement, printing pressure was 200 N and printing velocity was 1 m/sec. The properties of newspaper samples (basis weight, bulk density, roughness, smoothness, porosity, i. e.) were examined in accordance with KS and TAPPI standard testing methods. The result of this study are respected for usefulness printing quality management of Korean newsprint.