• Computers and Concrete
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• v.18 no.3
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• pp.367-388
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• 2016

In this paper, a simple practical method is introduced in which a simple weight measurement of concrete and finite element numerical analysis are used to determine the moisture transfer coefficient of concrete with a satisfactory accuracy. Six concrete mixtures with different water-to-cementitious material (w/cm) ratios and two pozzolanic materials including silica fume and zeolite were examined to validate the proposed method. The comparison between the distribution of the moisture content obtained from the model and the one from the experimental data during both the wetting and drying process properly validated the performance of the method.With the proposed method, it was also shown that the concrete moisture transfer coefficient considerably depends on the pore water saturation degree. The use of pozzolanic materials and also lowering w/cm ratio increased the moisture transfer coefficient during the initial sorption, and then, it significantly decreased with an increase in the water saturation degree.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.242-246
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• 2010

To determine the trajectories and the impact of rain drops on the facade of a tall building, a particle tracking method is employed form steady state simulation of turbulent flow around the building. The simulation is performed for the upper part of the building comprising a detailed louver system. Rain is trapped at relative high rates on the roof and the penthouse, with Local Intensity Factors (LIF's) of the order of 1. The upper parapets and upper floors get a fair amount of wetting with LIF's of the order of 0.6. The wetting decreases downwards reaching values of 0.2 to 0.25 at the level of the louver system.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.81-86
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• 2000

To evaluate the possibility of the partial melting soldering. wettability of partial melted solders was measured using wetting balance. Off eutectic Sn-Pb allows are wettable in their partial melting zone. Especially, Pb rich alloys showed excellent wettability while wettability of Sn rich alloys were adequate or poor. It is found that wettability increases over $200^{\circ}C$ regardless of composition liquid fraction and phases of the original alloy Sn-7Ag alloy showed good wettability in their partial melting zone, while Sn-65Bi alloy was non-wettable under their melting points.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.31-40
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• 2011

Purpose: This study was performed to investigate the actual state about ultrasonic cleaning of soft contact lenses in local optical shops and evaluate the removal effect of protein deposit on soft contact lenses with different lens containers by ultrasonic cleaner for eyeglasses. Methods: The actual state about ultrasonic cleaning of soft contact lenses was surveyed in total 75 local optical shops in Seoul, Korea. The cleaning efficacy of different lens containers was compared by measuring the protein remained on ocufilcon D contact lenses after washing by an ultrasonic cleaner for eyeglasses. The changes on surfaces and wetting angles of ocufilcon D contact lenses by repeat ultrasonication were further investigated. Results: The main purpose to use ultrasonic cleaners in local optical shops was rapid cleaning. The ultrasonic cleaning efficacy of ocufilcon D contact lenses with glass containers was little higher than it with plastic containers, but was not significantly different. The changes on surfaces and wetting angles of ocufilcon D contact lenses in a plastic lens container by repeat ultrasonication such as 30 and/or 60 times were shown. Conclusions: There was not significant difference in cleaning efficacy between glass and plastic lens containers. However, repeat cleaning with ultrasonic cleaner for eyeglasses would be carefully considered since some significant changes in the parameters of lens surface and wetting angles were detected by repeat ultrasonification even when lens containers were used for ocufilcon D contact lens during ultrasonictions.

• Computers and Concrete
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• v.15 no.2
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• pp.183-198
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• 2015

Chloride ingress implies a complex interaction between physical and chemical process, in which heat, moisture and chloride ions transport through concrete cover. Meanwhile, reinforced concrete structure itself undergoes evolution due to variation in temperature, relative humidity and creep effects, which can potentially change the deformation and trigger some micro-cracks in concrete. In addition, all of these process show time-dependent performance with complex interaction between structures and environments. In the present work, a time-dependent behavior of chloride transport in reinforced concrete beam subjected to flexural load is proposed based on the well-known section fiber model. The strain state varies because of stress redistribution caused by the interaction between environment and structure, mainly dominated by thermal stresses and shrinkage stress and creep. Finally, in order to clear the influence of strain state on the chloride diffusivity, experiment test were carried out and a power function used to describe this influence is proposed.

• Journal of Information Display
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• v.9 no.4
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• pp.6-10
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• 2008

In this study, the selective-wettability-inscription (SWI) technique for the wet-etchingless fabrication of surface microstructures applicable to wide-viewing liquid crystal displays (LCDs) on plastic substrates was demonstrated. On the basis of the selective wetting of the photopolymer, the bi-level microstructures were spontaneously formed to serve as spacers for maintaining uniform cell gap and protrusions for the generation of multi-domains. The LC cell that has bi-level microstructures shows good extinction in the field-off state and a wide-viewing property in the field-on state. The SWI technique would be useful for the fabrication of flexible displays on plastic substrates.

• Journal of Sensor Science and Technology
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• v.25 no.3
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• pp.213-217
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• 2016

The superhydrophobic and superoleophobic meshes surfaces have been used in various applications such as self-cleaning, anti-icing, gas exchange, oil-water separation, sound-wave penetrable anti-wetting structures, etc. In particular, there are many studies for oil-water separation with environmental issues. Because of high pressure and dynamic environment, oil-water separation filters must have stable surface properties as super-hydrophobicity and superoleophobicity. The oleophobicity of surface depends on the surface chemistry and roughness of the surface. The roughness of oleophobic surface enhances its static contact angle and stability. The multi-scale hierarchical structure provides a stable superhydrophobic state by maintaining a Cassie state. In this research, we fabricated a superoleophobic mesh with a multi-scale hierarchical structure to increase the pressure resistance and adjusted a size of the mesh hole.

• Journal of Korea Foundry Society
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• v.37 no.5
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• pp.157-163
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• 2017

In the present study, the microstructural evolution and deformation behavior of AA 2014 aluminum alloys with different microstructures in a semi-solid state were investigated. For a given alloy, applied load and deformation time, the measured strain was higher at a higher temperature, indicative of a lower solid fraction. When a large proportion of the liquid was present as intragranular droplets, the alloy would not as easily deform because the effective liquid fraction between the solid grains had decreased. Greater deformation was achieved with higher grain boundary misorientations due to the enhanced wetting of the grain boundaries with liquid. A semi-empirical constitutive model is proposed for semi-solid deformation under the conditions in the present study. The mechanism of semi-solid deformation incorporates the initial flow of the liquid in the early stages of deformation, followed by a more gradual increase in the strain due to deformation by grain sliding accompanied by self-diffusion in the solid grains.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.544-550
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• 2013

A grooved surface with anisotropic wettability was fabricated on a silicon substrate using photolithography, reactive ion etching, and a KOH etching process. The contact angles (CAs) of water droplets were measured and compared with the theoretical values in the Cassie state and Wenzel state. The experimental results showed that the contact area between a water droplet and a solid surface was important to determine the wettability of the water. The specimens with native oxide layers presented CAs ranging from $71.6^{\circ}$ to $86.4^{\circ}$. The droplets on the specimens with a native oxide layer could be in the Cassie state because they had relatively smooth surfaces. However, the CAs of the specimens with thick oxide layers ranged from $33.4^{\circ}$ to $59.1^{\circ}$. This indicated that the surface roughness for a specimen with a relatively thick oxide layer was higher, and the water droplet was in the Wenzel state. From the CA measurement results, it was observed that the wetting on the grooved surface was anisotropic for all of the specimens.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.2
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• pp.121-127
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• 1985

This study was designed to gain practical data on the use of soil conditioners for more efficient water managements and to establish the optimum levels of structural properties for soil conditioning. A sandy loam and a silt loam soil were each treated with two different soil conditioners, hydrophobic Bitumen or hydrophilic Uresol. The perspex tube 34 cm long were packed homogeneously with air dried soil up to 2 cm below the top, then covered over 2 cm of treated or untreated aggregates. The infiltration rate into the soil columns was measured under simulated rainfall condition. The evaporation study was carried out in the wind tunnel, and the changes of soil moisture distribution of the columns following and during the evaporation were determined by a gamma ray scanner. The infiltration rate of water into the soil column was increased to 18.7-50.8% by the Uresol treatment but it was decreased to less than 25% of control by the Bitumen treatment. Evaporation was decreased to 22.0-68.1% by the Bitumen treatment and to 38.7-68.4% by the Uresol treatment. The water use efficiency of Uresol treated column was increased to more than twice as much as that of untreated soil. Aggregate stability and wetting angle were related to water infiltration and evaporation. A positive and highly significant logarismic relationship was found between the infiltration rate and stability index-wetting angle, evaporation rate and instability index-wetting angle. It was considered that the structural stability is more important than wetting angle. This is true because the structural stability is always positively correlated to water saving, however wettability is positively correlated to the infiltration, and negatively correlated to water saving during the evaporation.