• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1523_1524
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• 2009

Inkjet technology has various merits as a direct patterning process in plenty of industrial applications, but critical issue such as coffee ring effect should be overcome for the application to an industrial manufacturing process. In this paper, we introduced the morphological analysis of inkjet printed pattrerns on the characristics of inks and substrates. In case of Triethlene Glycol Monoethly Ether based ink, the coffee ring effect was observed. However, an ethanol based ink showed the round shaped morphology under the same printing conditions and surface conditions. An ink consisted of the solvent with high boiling point results in coffee ring effect. This experimental results showed that the morphological change of the printed droplet is caused by the main solvent of ink, rather than the metal content, viscosity and surface tension.

• Journal of Sericultural and Entomological Science
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• v.25 no.2
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• pp.58-64
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• 1984

Silk fabric was printed with the reactive dyes (mono and di-chlorotriazinyl type) in order to investigate the change of adsorption and fixation by steaming time, viscosity of dyeing paste, and alkali concentration. It was found that the amount of adsorption and fixation of mono-chlorotriazinyl type dye increased with the increase of steaming time, while di-chlorotriazinyl type dye showed the maximum uptake at 20 minutes. The amount of dye uptake of each dye showed the maximum value at 340 cp of dyeing paste. The light fastness of each dye was poor but the washing fastness was excellent.

• Journal of the Korean Society of Combustion
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• v.11 no.4
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• pp.27-35
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• 2006

The impacts of equivalence ratio on flow structure and flame dynamic in a model gas turbine combustor are investigated using large eddy simulation(LES). Dynamic k-equation model and G-equation flamelet model are employed as LES subgrid model for flow and combustion, respectively. As a result of mean flow field for each equivalence ratio, the increase of equivalence ratio brings about the decrease of swirl intensity through the modification of thermal effect and viscosity, although the same swirl intensity is imposed at inlet. The changes of vortical structure and turbulent intensity etc. near flame surface are occurred consequently. That is, the decrease of equivalence ratio can leads to the increase of heat release fluctuation by the more increased turbulent intensity and fluctuation of recirculation flow. In addition, the effect of inner vortex generated from vortex breakdown on the heat release fluctuation is increased gradually with the decrease of equivalence ratio. Finally, it can be identified that the variations of vortical structure play an important role in combustion instability, even though the small change of equivalence ratio is occurred.

• Journal of the Korean Graphic Arts Communication Society
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• v.21 no.2
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• pp.75-87
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• 2003

Printing inks are mainly composed of pigment and vehicles. Among these components, the Vehicle affect the rheologic property of the ink the most but pigment content of characteristic also after to the fluidity property not less than the vehicle. In the study, It is tested effect to the ink fluidity and structure recovery according to change the pigment particle size. The ink fluidity have been observed by using rheometer at the various conditions and it has been tested to observe what the ink fluidity has different means. In result We have found that the viscosity value of the low shear rate range has relatively higher value with decreasing the pigment particle size in the ink. Also, it has been found that when the pigment particle size decreases, the yield stress gradually increase. In the case of ink's structure recovery, when the pigment particle size decreases in the ink, the less changing shear rate, and it takes less time to recover.

• Applied Biological Chemistry
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• v.48 no.4
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• pp.404-410
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• 2005

Sopoongsan is an oriental medicinal composition including 12 medicinal herbs. Sopoongsan is known to have anti-inflammatory, antimicrobial, anti-allergic, and anticancer effects on human skin. The results of stability test showed that the creams containing Sopoongsan extracts were very stable at both accelerated temperature conditions and sun-light. And pH and viscosity of each cream did not change greatly for 56 days. From the particle size and rheological measurements, it can be known that when the amount of the Sopoongsan extracts increases, the mean value of particle size decreases, and the value of the complex modulus and loss angle increases, which means the Sopoongsan extracts help stabilize the emulsion. From the result of human patch test to assess the safety of cream containing Sopoongsan extracts, there was no stimulus of negative reaction on skin. In result of the user tests, it can be known that the higher concentration of the Sopoongsan was preferred by customers.

• Journal of the Korea Furniture Society
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• v.21 no.2
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• pp.126-132
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• 2010

High wear resistances are obtained with an additional coating of the surface of the decor film in the same operation of impregnating with low viscosity melamine resin by liquid overlay system. The cellulosic fibers have a good adhesion to the corundum particles and keep them sufficiently homogeneous in the blend with the resin. The amount of these fibers in nearly as big as it is in a common overlay in relation to the resin. Therefore these fibers keep the resin inside during the press process and consequently very the surface of the decor print of the film. That means that the corundum particles are equally dissipated throughout the entire layer over the decor. The change of the color of the print is nearly not visible as the particles are almost equally dissipated. Looking to the flooring purposes of liquid overlay one can see that by the lesser exposure of the corundum particles on the very surface, there is no longer an abrasive surface but a feeling like a normal melamine surface.

• Computers and Concrete
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• v.11 no.1
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• pp.39-49
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• 2013

The use of ground fly ash in concrete can increase the risk of slump loss due to the drastic surface change of the particles after the grinding treatment and the accelerated reaction compared to the untreated ash. This study is aimed at the early age hydration and time-dependent rheology changes of cement paste containing ground fly ash. An original fly ash is ground into different fineness and the hydration of cement paste containing the ground fly ash is monitored with the ultrasound propagation method. The zeta potentials of the solid particles are measured and the changes of rheological parameters of the cement pastes with time are analyzed with a rheometer. A particle packing model is used to probe packing of the solid particles. The results show that the early age hydration of the paste is strongly promoted by replacing Portland cement with fly ash up to 30 percent (by mass), causing increase of the yield stress of the paste. The viscosity of a paste containing ground fly ash is lower than that containing the untreated ash, which is explained by the denser packing of the solid particles.

• Journal of Powder Materials
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• v.24 no.3
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• pp.223-228
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• 2017

Nanopowders provide better details for micro features and surface finish in powder injection molding processes. However, the small size of such powders induces processing challenges, such as low solid loading, high feedstock viscosity, difficulty in debinding, and distinctive sintering behavior. Therefore, the optimization of process conditions for nanopowder injection molding is essential, and it should be carefully performed. In this study, the powder injection molding process for Fe nanopowder has been optimized. The feedstock has been formulated using commercially available Fe nanopowder and a wax-based binder system. The optimal solid loading has been determined from the critical solid loading, measured by a torque rheometer. The homogeneously mixed feedstock is injected as a cylindrical green body, and solvent and thermal debinding conditions are determined by observing the weight change of the sample. The influence of the sintering temperature and holding time on the density has also been investigated. Thereafter, the Vickers hardness and grain size of the sintered samples have been measured to optimize the sintering conditions.

• Journal of Conservation Science
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• v.34 no.4
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• pp.295-303
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• 2018

The application of reinforcing agents with hydraulic property and strength development characteristics was studied under conditions similar to those of mural-painting mortar made with oyster shell powder. Reinforcement mortar made with oyster shell powder showed hydraulic properties and strength to supplement the weaknesses of natural hydraulic lime(NHL); this confirmed its possibility as a wall-reinforcing material with enough strength for preserving mural paintings. Reinforcement mortar 1 showed hydraulic property and general characteristics of lime mortar, such as consistency and viscosity, as well as lower strength and higher whiteness compared to an NHL product. For Reinforcement mortar 2, the original wall sample characteristics were reflected by mixing more shell produced through calcination; and it showed similar strength to that of Reinforcement mortar 1 as well as high whiteness. In measuring the contraction ratio of reinforcement mortar samples, Reinforcement mortar 1 and 2 showed more stability in property change compared to the NHL Group.

• Current Research on Agriculture and Life Sciences
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• v.30 no.1
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• pp.41-50
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• 2012

As a part of abating formaldehyde emission of urea-formaldehyde resin, this study was conducted to investigate the rmalcure kinetics of both neat and modified urea-formaldehyde resins using differential scanning calorimetry. Neat urea-formaldehyde resins with three different formaldehyde/urea mol ratios (1.4, 1.2 and 1.0) were modified by adding three different additives (sodium bisulfite, sodium hydrosulfite and acrylamide) at two different levels (1 and 3wt%). An isoconversional method at four different heating rates was employed to characterize thermal cure kinetics of these urea-formaldehyde resins to obtain activation energy ($E{\alpha}$) dependent on the degree of conversion (${\alpha}$). The $E{\alpha}$ values of neat urea-formaldehyde resins (formaldehyde/urea = 1.4 and 1.2) consistently changed as the ${\alpha}$ increased. Neat and modified urea-formaldehyde resins of these two F/U mol ratios did show a decrease of the $E{\alpha}$ at the final stage of the conversion while the $E{\alpha}$ of neat urea-formaldehyde resin (formaldehyde/urea = 1.0) increased as the ${\alpha}$ increased, indicating the presence of incomplete cure. However, the change of the $E{\alpha}$ values of all urea-formaldehyde resins was consistent to that of the Ea values. The isoconversional method indicated that thermal cure kinetics of neat and modified urea-formaldehyde resins showed a strong dependence on the resin viscosity as well as diffusion control reaction at the final stage of the conversion.