• Transactions of Materials Processing
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• v.24 no.2
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• pp.83-88
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• 2015

For chromaticity correction, it is necessary to dispense high viscosity phosphor slurry since it greatly affects the performance of white LEDs. However, it is quite difficult to dispense high viscosity fluorescent materials. In the current study, micro-discharge electrostatic printing has been used for dispensing various high viscosity phosphor slurries. We have achieved dispersions of up to 50 µg using drop on demand (DOD) discharge experiments. The experiments were conducted with different combinations of process variables such as applied voltage, pneumatic pressure, and frequency.

• Korea-Australia Rheology Journal
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• v.16 no.3
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• pp.153-160
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• 2004

Open microcellular foams having small-sized cell and good mechanical properties are desirable for many practical applications. As an effort to reduce the cell size, the microcellular foams combining viscosity improvers into the conventional formulation of styrene and water system were prepared via high internal phase emulsion polymerization. Since the material properties of foam are closely related to the solution properties of emulsion state before polymerization, the flow behavior of emulsions was investigated using a controlled stress rheometer. The yield stress and the storage modulus increased as viscosity improver concentration and agitation speed increased, due to the reduced cell size reflecting both a competition between the continuous phase viscosity and the viscosity ratio and an increase of shear force. Appreciable tendency was found between the rheological data of emulsions and the cell sizes of polymerized foams. Cell size reduction with the concentration of viscosity improver could be explained by the relation between capillary number and viscosity ratio. A correlative study for the cell size reduction with agitation speed was also attempted and the result was in a good accordance with the hydrodynamic theory.

• Journal of Energy Engineering
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• v.13 no.4
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• pp.235-241
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• 2004

This experiment was undertaken to investigate the atomization characteristics of the high viscosity biodiesel blended fuel and ultrasonic energy irradiation one. Test fuels were conventional diesel fuel and biodiesel one. We compared to the characteristics of viscosity and surface tension, SMD between high viscosity biodiesel blended fuel and ultrasonic energy irradiation one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension were measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600c. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy irradiation situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than those of the conventional situation.

• Journal of the Korea Institute of Building Construction
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• v.19 no.3
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• pp.219-228
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• 2019

The aim of the research is to provide a fundamental data of low viscosity typed superplasticizer (SP) on cement-based materials incorporating various supplementary cementitious materials (SCMs). As a relatively new product, low-viscosity typed SP has introduced for high performance concrete with high viscosity due to its high solid volume fraction with various SCMs. However, there are not enough research or reports on the performance of the low viscosity typed SP with cement-based materials incorporting SCMs. hence, in this research, for cement paste and mortar, fluidity and rheological properties were evaluated when the mixtures contained various SCMs such as fly ash, blast furnace slag, and silica fume. From the experiment conducted, it was checked that the low viscosity typed superplasticizer decreased the plastic viscosity of the mixture as well as the yield stress. From the results of this research, it is expected to contribute on introduction of new type SP for high performance concrete or high-viscous cementitious materials.

• Tribology and Lubricants
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• v.30 no.3
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• pp.189-198
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• 2014

This paper presents the results of an experimental investigation of the correlation between the lubrication characteristics of an engine and its fuel economy. Improving the lubrication characteristics of the engine oil is one of the most efficient ways to improve a car's fuel economy. The methods to accomplish this include lowering the viscosity, adding a friction modifier and optimizing the shear stability index of a viscosity index improver. In addition, it is necessary to use different methods to reduce the friction to individual lubrication areas, because different lubrication regimes are used for different engine parts. The experimental investigation in this study is based on design of experiments ; this paper presents the results of a modified Sequence VID test, which is an ASTM standard test used to measure the effects of automotive engine oils on the fuel economy of passenger cars. The results demonstrate the effects of the following lubrication factors on the fuel economy : the low temperature cranking viscosity, high-temperature high shear (HTHS) viscosity, friction modifier, polymer type and shear stability index of the viscosity index improver. Moreover, this study involves an analysis of variance based on design of experiments. The test results show that the HTHS viscosity, friction modifier and shear stability index of the viscosity index improver are more effective than the other factors. Therefore, lowering the viscosity, adding a friction modifier and optimizing the shear stability index of a viscosity index improver should be considered to improve fuel economy.

• Journal of the Korean Society of Tobacco Science
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• v.22 no.1
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• pp.45-50
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• 2000

In order to improve the sowing practice, pelleted seeds of tobacco NC 82(Nicotiana tobacco L.) were manufactured in use of binders at the different levels of viscosity, and their physical properties according to pellet size and biological activity in seed germination were investigated while storage time elapsed. Proper range of the binder viscosity for the pellet formation was 20.3-37.2 m.pas. At the high level of viscosity(45.7 m.pas) took longer time to form the pellet and pelleting was not easy. The high binder viscosity and large pellet size revealed higher level in hardness of the pelleted tobacco seeds, which caused the longer splitting time of pellets in water. High level of binder viscosity(37.2 m.pas) in pelleted seeds led to decrease the biological activity of tobacco seed germination by the storage at 4 t over 30 days. But at the level of 20.3m.pas in binder viscosity, the germination of pelleted seeds was little affected by the long storage time to 120 days.

• Journal of the Korean Graphic Arts Communication Society
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• v.21 no.2
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• pp.89-100
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• 2003

We have reviewed the method for surface tension of printing inks. Most of the methods fir for the low viscosity inks and solvents for inks. However, the inks for the offset lithography and intaglio should have high viscosity and high tack. The elongation of the ink filaments has more effect on the measuring surface tension than the energy of the surface molecules. In this paper, we propose the elongation method to estimate the surface tension of high viscosity printing inks. Even though we could measure the surface tension for low viscosity inks such as gravure and screen, elongation method could more useful to estimate the surface tension of lithography and intaglio inks than any other methods.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.9-17
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• 1994

Effect of Newtonian and non-Newtonian oils on minimum ol film thickness in engine journal bearing were investigated at various oil viscosities. The influence of oil viscosity and engine operating conditions on minimum oil film thickness of main bearing and con-rod bearing was examined. Minimum oil film thickness for Newtonian oils increased uniformly with kinematic viscosity. But the correlation between kinematic viscosity and minimum oil film thickness was very poor for non-Newtonian oils. According to the straight-line regression analysis for non-Newtonian oils, high temperature high shear viscosity at 1 $1{\times}10^6Sec^{-1}$, $150^{\circ}C$ increase the coefficient of determination from 0.41 to 0.77. Con-rod bearing showed better correlation between minimum oil film thickness and engine operating conditions than main bearing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.689-696
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• 2017

The practical applications of ordinary high-fluidity concrete have been limited due to several drawbacks, such as high hydration heat, high amount of shrinkage, and non-economic strength development. On the other hand, due to its advantages, such as improvement of construction quality, reduction of construction cost and period, the development of high-fluidity concrete is a pressing need. This study examined the properties of high-fluidity concrete, which can be manufactured on the low binders using a viscosity agent to prevent the segregation of materials. The optimal viscosity agent was selected by an evaluation of the mechanical properties of high-fluidity concrete among six viscosity agents. The acrylic type and urethane type viscosity agents showed the best performance within the range where no material separation occurred. The mechanical properties were evaluated to examine the optimal amount of AC and UT viscosity agent added by mixing two viscosity agents according to the adding ratio and blending them together with high performance water reducing agent. When the ratio of the AC : UT viscosity agents was 5:5, it was most suited for high-fluidity concrete with low binders by increasing the workability and effect of the reducing viscosity.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.353-358
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• 2017

The aim of this research is providing a fundamental idea on reducing viscosity of high performance cementitous materials. In rheological aspect, to determine the fluidity of the cementitious materials, both yield stress and viscosity should be controlled. For the high performance cementitious materials with low water-to-binder ratio and high volume fraction, it was difficult to reduce the viscosity with superplasticizer while reducing yield stress was relatively easy. Hence, in this research, with the goal of reducing viscosity of the cementitious materials, both ways of reducing viscosity were suggested: achieving proper combination of powder conditions, and adding low-viscosity typed water reducer. First, by replacing various byproduct powders, specifically, raw coal ash and wasted limestone powder showed favorable results on reducing viscosity of the cement paste. Regarding the low viscosity typed superplasticizer, it showed a good performance on reducing viscosity comparing with generic superplasticizer. Therefore, based on the results of this research, it is expected to provide a fundamental idea on reducing viscosity of cementitious materials by various methods.