• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.368-373
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• 1998

Prepackaged system consists out of a dry mix which contains cement, sand, redispersible polymer powder and admixtures in the right proportions. The purpose of this study is to evaluate the quality of prepackaged-type polymer-modified mortar products using redispersible poly(ethylene-vinyl acetate)(EVA) powder. Polymer-modified mortars using the redispersible polymer powder with powdered with powdered shrinkage-reducing agent were prepared with cellulose fiber contents of 0, 0.5, 1.0% and shrinkage-reducing agent contents of 0, 4%, and tested for drying shrinkage, strength, adhesion in tension, water absorption. From the test results, the prepackaged-type polymer-modified mortar products with 4% of shrinkage-reducing agent content give good properties. and that their properties largely depends on the shrinkage-reducing agent content rather than the cellulose fiber contents.

• Textile Coloration and Finishing
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• v.8 no.6
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• pp.47-54
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• 1996

In order to develop the air flow finishing machine with low tension drying and surface modification by high impact effect, the treatment characteristics and the moving speed of fabrics was analysed and investigated in the newly developed system. The change of handle before and after treatment of fabrics measured using Kawabata system. The moving speed in air nozzle was affected by an air pressure of blower, and the maximum value was 1,000 m/min. In accordance with the change of handle, the treatment effect was very different compared with untreated fabrics. And the drape properties of fabrics increased about 10∼45% compared with untreated one.

• Journal of Institute of Convergence Technology
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• v.5 no.2
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• pp.43-48
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• 2015

Deep eutectic solvents (DESs) are now broadly understood as a new kind of ionic liquid (IL) because they exhibit many characteristics and properties similar with ILs. The DESs made of quaternary ammonium salt blended with one of hydrogen bonding donor (HBD) compounds behave as ILs even at very low temperature. In this study, properties such as density, viscosity, surface tension, conductivity, and electrochemical behavior of DESs were reported and their applications were reviewed. Study on DESs has been drawn attention on application in metal finishing, but these solvents can be used in a variety of synthesis, and their potentials have been demonstrated in various areas. DESs are expected to offer applicability by extending the types of salts and hydrogen bond donor mixtures.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.259-264
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• 2004

The hot embossing process as a method for the fabrication of polymer is becoming increasingly important because of its simple process, low cost, high replication fidelity and relatively high throughput. In this paper, we carried out experimental studies and numerical simulations in order to understand the viscous flow of polymer film during hot embossing process. As the initial step of quantitating the hot embossing process, simple parametric studies for the embossing conditions have been carried out using high resolution masters which patterned by DRIE process. Under different embossing times and pressures, the viscous flow of PMMA films into micro/nano cavities has been investigated. Also, the viscous flow during the hot embossing process has been simulated by the continuum based FDM analysis considering micro/nano effect, such as surface tension and contact angle.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.494-499
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• 2005

The chemical, physical, and emulsifying properties of BSF-1, which is an extracellular lipopolysaccharide biosurfactant produced by Klebsiella oxytoca strain BSF-1, were studied. BSF-1 was found to be composed mainly of carbohydrate and fatty acids. The average molecular weight was $1,700{\sim}2,000 kDa$. The polysaccharide fraction contained L-rhamnose, D-galactose, D-glucose, and D-glucuronic acid at a molar ratio of 3:1: 1:1. The fatty acid content was 1.1 % (w/w) and consisted mainly of palmitic acid (C16:0), 3-hydroxylauric acid (3-OH-C12:0), and lauric acid (C12:0). In terms of thermal properties, BSF-1 was revealed to have inter- and intra-molecular hydrogen bonds. The hydrodynamic volume (intrinsic viscosity) of BSF-1 was 22.8dL/g. BSF-1 could be maintained as a stable emulsion for 48 h through a low-level reduction in surface tension. The optimal emulsification temperature was $30^{\circ}C$. Emulsification by BSF-1 was efficient at both acidic and neutral pH values.

• Tuberculosis and Respiratory Diseases
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• v.38 no.3
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• pp.228-235
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• 1991

Pulmonary surfactant is a lipoprotein complex composed primarily of phospholipid and lungspecific apoproteins that reduces surface tension in the alveolus and maintains alveolar stability at low lung volume. Three families of lung-specific apoproteins have been described: SP-A, a glycoprotein with a reduced molecular weight of 28~36 KDa. SP-B a hydrophobic protein with a nonreduced molecular weight of 18 KDa, and SP-C a hydrophobic protein with a non-reduced molecular weight of 5~8 KDa. Surfactant proteins have important roles in regulating surfactant metabolism as well as in determining its physical properties. The synthesis of the active surfactant peptides appears to be modulated by system with considerable complexity, including numerous levels of regulation such as cell-specific, hormonal and developmental controls. Endotoxin appears to alter surfactant protein mRNAs differentially. It is hoped that the elucidation of the factors controlling the synthesis and metabolism of the surfactant proteins will aid in understanding the pathogenesis of hyaline membrane disease and offer new avenues for the therapy and diagnosis of ther pulmonary disorders as well.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.8 s.173
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• pp.159-164
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• 2005

The Hot Embossing Lithography(HEL) as a method fur the fabrication of the nanostructure with polymer is becoming increasingly important because of its simple process, low cost, high replication fidelity and relatively high throughput. In this paper, we carried out experimental studies and numerical simulations in order to understand the viscous flow of the polymer (PMMA) film during the hot embossing process. To grasp the characteristics of the micro patterning rheology by process parameters (embossing temperature, pressure and time), we have carried out various experiments by using the nickel-coated master fabricated by the deep RIE process and the plasma sputtering. During the hot embossing process, we have observed the characteristics of the viscoelastic behavior of polymer. Also, the viscous flow during the hot embossing process has been simulated by the continuum based FDM(Finite Difference Method) analysis considering the micro effect, such as a surface tension and a contact angle.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.269-270
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• 2006

A finite difference lattice Boltzmann model which allows us to simulate gas-liquid two-phase flows with large density difference, for instance, 800 times for air and water is considered. Two-particle model is used and the density difference is introduced by changing the acceleration according to the fluid density. Numerical measurement of surface tension agrees well with theoretical predictions. Simulations of two-phase phenomenon for phase-transition is carried out, showing applicability of the model for two-phase flows. The two-dimensional cavitating flow around a board set up in the fluid way is also simulated. As a result, it was confirmed that the FDLB method with two-particle model was effective in numerical simulation of cavitating flow and the bubble periodically grew up at the low pressure area behind the board, in which the fluid condition was influenced by the cavitation number.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.394-398
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• 2004

This study was carried out to plan the prevention of the generation and discharge of acid mine drainage (AMD). Hydraulic characteristics were tested with the disk tension infiltrometer around the waste rock dump of the Imgi abandoned pyrophyllite mine in Busan, Korea. Because the waste rock dump of the Imgi mine have very low infiltration rate, most of rain was expected flowing into adjoined stream through the slope or plane as surface flow rather then throughflow or ground water. But slopes of the waste rock dump have many 'V' type erosion gullies and consist multi-layers. These gullies and multi-layers have coarse clastic particle layer which have very large hydraulic conductivity. So through these coarse clastic particle layers a large part of rain flow into ground. And also these layers could be played a function of aeration path, which induced oxidation of sulfide minerals and generation of AMD continuously.tinuously.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.478-483
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• 2003

This paper describes spray characteristics of a swirl injector which is intended for use in a HCCI engine. Many optical diagnostics such as laser diffraction methods, and high speed camera photography are applied to measure the spray drop diameter and to investigate the spray development process. The effect of fuel properties on the spray characteristics was investigated using three different fuels because HCCI combustion is tolerant of the chemical composition of various fuels. From these results, the HCCI injector formed a hollow cone sheet spray rather than a liquid jet and the atomization efficiency is high for the low-pressure injector. The SMD of test injector was ranged from $15{\mu}m$ ${\mu}m$ We also found that the spray breakup characteristics were dependent on the fuel properties such as density, viscosity, and surface tension.