• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.106-111
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• 2017

When a substrate with a pixel-defining layer (bank) is coated, there arises capillary force due to surface tension and adhesive forces between a solvent and the bank layer. It brings in a degradation of film thickness and emission uniformities within pixels. With an attempt to suppress it, we have performed fluid flow simulations of capillary arise by varying the contact angle of bank and the bank structure. We have first demonstrated that the fluid flow model can reproduce the capillary phenomenon that was observed experimentally. It has been found that capillary arise can be suppressed using a hydrophobic material for the bank layer. Furthermore, it was suppressed by tilting the sidewalls outwardly (i.e., using a positive photoresistor). We can obtain very uniform films when the slope is $50^{\circ}$ with the contact angle of $40^{\circ}$.

• Journal of the Korean GEO-environmental Society
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• v.23 no.1
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• pp.31-37
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• 2022

This study is focused on developing a technology to prevent high-strength wire net from expanding damage due to insufficient performance of the existing PVC coating net. For the test method, reference was made to ISO 17746, an international standard. In addition, as a result of referring to the test criteria, a wire net was fabricated with a width of 1,000 mm or more a size of 1 m² sample. load-displacement curve of the test results was compared to analyze how much performance was improved compared to the existing PVC coating net.

• Corrosion Science and Technology
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• v.23 no.2
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• pp.93-103
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• 2024

In the present work, a phase-field model for dendritic solidification is applied to hot-dip ZnAlMg coatings to elucidate the morphology of zinc dendrites and the solute segregation leading to the formation of eutectics. These aspects define the microstructure that conditions the corrosion resistance and the mechanical behaviour of the coating. Along with modelling phase transformation and solute diffusion, the implemented model is partially coupled with the tracking of crystal orientation in solid grains, thus allowing the effects of surface tension anisotropy to be considered in multi-dendrite simulations. For this purpose, the composition of a hot-dip ZnAlMg coating is assimilated to a dilute pseudo-binary system. 1D and 2D simulations of isothermal solidification are performed in a finite element solver by introducing nuclei as initial conditions. The results are qualitatively consistent with existing analytical solutions for growth velocity and concentration profiles, but the spatial domain of the simulations is limited by the required mesh refinement.

• Biomolecules & Therapeutics
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• v.16 no.4
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• pp.425-430
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• 2008

The objectives of this study were to prepare PLGA film onto the surface of the capsular tension ring (CTR) for controlled drug release and investigate the influence of plasticizers, the test drug and measurement conditions on flexibility of the film. Film solutions were prepared by dissolving PLGA, plasticizer (triethyl citrate, TEC or polyethylene glycol, PEG), test drug (dexamethasone) in ethyl acetate then films were prepared by spray coating and evaporation method. Then, the flexibility of PLGA film was determined by elongation test. The addition of plasticizer, PEG or TEC to PLGA copolymer caused a depression of glass transition temperature ($T_g$) and the elasticity of PLGA films increased. The addition of dexamethasone to the PLGA/TEC matrix decreased the flexibility of film. Dimensional factors of the PLGA films such as width and thickness were significantly influenced on flexibility of films and film length and elongation speed had no considerable influence on elongation of films. In this study, sufficiently flexible and stable PLGA films capable of being coated onto CTR could be prepared. This PLGA films can be used as a platform for local drug delivery.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.1-7
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• 2008

In the process of continuous hot-dip galvanizing, it is well known that the gas wiping through an air knife system is most effective because of its uniformity in coating thickness, possibility of thin coating, workability in high speed, and simplicity of control. However, gas wiping used in the galvanizing process brings about a problem of splashing at the strip edge above a certain high speed of process. It is also known that the problem of edge splashing is more harmful than that at the mid strip surface. For a given liquid(of a certain viscosity and surface tension), the onset of splashing mainly depends upon the strip velocity, the gas-jet pressure, and the nozzle's stand-off distance. In these connections in the present study, we proposed three kinds of air knife system having nozzles of constant expansion rate, and compared the jet structures issuing from newly proposed nozzle systems with the result by a conventional one. In numerical analysis, the governing equations are consisted of two-dimensional time dependent Navier-Stokes equations, and the standard k-${\varepsilon}$ turbulence model is employed to solve turbulence stress and so on. As the result, it is found that we had better use the constant expansion-rate nozzle which can be interpreted from the point view of the energy saving for the same coating thickness. Also, we better reduce the size of separation bubble and enhance the cutting ability at the strip surface, by using an air-knife having constant expansion-rate nozzle.

• Structural Engineering and Mechanics
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• v.32 no.4
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• pp.477-488
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• 2009

A slip critical joint has various values to adopt the proper slip coefficient in various conditions of faying surfaces in the following codes: AISC, AIJ and Eurocode 3. However, the Korean Building Code still regulates the unique slip coefficient, 0.45, regardless of the diverse faying conditions. In this study, the slip resistance test, including five kinds of surface treatments were conducted to obtain the proper slip coefficients available to steel plate KS SM490A. The faying surfaces were comprised of a clean mill, rust, red lead paint, zinc primer, and shot blast treatment. The candidates for high strength bolts were torque-shear bolts, torque-shear bolts with zinc coating, and ASTM A490 bolts. Based on the test results, the specimens with a shot blasted surface and rusted surface exhibited $k_s$, 0.61, and 0.5, respectively. It is recommended that the specimens with zinc primer exhibit $k_s{\geq}0.40$. The clean mill treated surface had prominently lower values, 0.27. For red lead painted treatment, the thickness of the coating affects the determinant of slip coefficient, so it is necessary to establish a minimum $k_s$ of 0.2, with a coating thickness of 65 ${\mu}m$. During 1,000 hours of relaxation, the uncoated surfaces exhibited the loss of clamping force behind 3%, while the coated surfaces within a certain limited thickness exhibited the loss of clamping within a range of 4.71% and 8.37%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.130-136
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• 2017

The present work is for an evaluation of tension behavior and surface deterioration of FRP Hybrid Bar due to UV exposure and freezing/thawing(F/T) actions. For the work, FRP Hybrid Bar is subjected to UV exposure test, then F/T test is performed successively to 180 cycles. In FRP Hybrid Bar, no significant surface deterioration is evaluated after UV exposure. Tension hardening performance, a unique engineering advantage of FRP Hybrid Bar, is still maintained after F/T test. The performance in FRP Hybrid Bar exposed to UV is still effective. FRP Hybrid Bar exposed to UV have almost similar tension behavior of FRP Hybrid Bar without UV exposure. Although F/T cycles increase to 180, steel rebar, FRP Hybrid Bar, and FRP Hybrid Bar exposed to UV show no significant changes in tension behavior. In the work, UV exposure and F/T actions are evaluated to have little negative effect on surface deterioration and tensile performance in FRP Hybrid Bar, however spalling of silica coating due to impact should be considered since it affects bonding strength to outer concrete.

• Membrane Journal
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• v.28 no.1
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• pp.21-30
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• 2018

In this study, homogeneous and defect-free ceramic ultrafiltration membranes were fabricated by using the sol-gel method. A boehmite sol was synthesized and coated onto the surface of alumina hollow fiber microfiltration membranes. The effect of sol viscosity and surface tension on the coating layer homogeneity and thickness was investigated. The optimum coating repetition using pristine sol was determined to be 3 times, as the samples coated more than 4 times showed delamination. Fixing the coating repetition to 3 times, the effect of sintering temperature was also studied in this work. The samples sintered at $1000^{\circ}C$ exhibited the highest pure water permeability with the molecular weight cut-off (MWCO) of approximately 51 kDa (10 nm dextran), and the samples sintered at 600, $800^{\circ}C$ displayed the MWCO of 12 kDa (5 nm dextran). The ultrafiltration membranes prepared in this work showed competitive performance compared to the reported ceramic ultrafiltration membranes.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.981-986
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• 2002

ACSR of the catenary wires is corrosion degradation progressed by the effect of atmospheric pollution. ACSR which consists of galvanized steel stranded aluminum. The inside of Steel Reinforced is hot-dipped zinc coating steel wire and it takes charge of tension. If ACSR is exposed in atmosphere, the galvanic corrosion is occurred because it is contacted with aluminum. It is occurred the chemical reaction rapidly so that the local a defect is also occurred. If the catenary wires are exposed in atmosphere of pollution conditions, it may cause to reduce the mechanical strength by corrosion degradation and may cause to damage the wires by micro cracks. Accordingly, this study presents the effects of mechanical properties through the corrosion of ACSR.

• Nuclear Engineering and Technology
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• v.38 no.8
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• pp.753-762
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• 2006

In this paper, works related to enhancement of the CHF are reviewed in terms of fundamental mechanisms and practical applications. Studies on CHF enhancement in forced convection are divided into two categories, CHF enhancement of internal flow in tubes and enhancement of CHF in the nuclear fuel bundle. Methods of enhancing the CHF of internal flows in tubes include enhancement of the swirl flow using twisted tapes, a helical coil, and a grooved surface; promotion of flow mixing using a hypervapotron; altering the characteristics of the heated surface using porous coatings and nano-fluids; and changing the surface tension of the fluid using additives such as surfactants. In the fuel bundle, mixing vanes or wire wrapped rods can be employed to enhance the CHF by changing the flow distributions. These methods can be applied to practical heat exchange systems such as nuclear reactors, fossil boilers, fusion reactors, etc.