• Journal of Electrochemical Science and Technology
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• v.10 no.4
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• pp.345-360
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• 2019

Polymer Electrolyte Membrane Fuel Cells (PEMFC) is one of the leading advanced energy conversion technology for the use in transport. It generates water droplets through the catalytic processes and dispenses the water through the gas-flowed microchannels. The droplets in the dispensing microchannel experience g-forces from different directions during the operation in transport. Therefore, this paper reviews the computational modelling topics of droplet dynamics behaviour specifically for three categories, i.e. (i) the droplet sliding down a surface, (ii) the droplet moving in a gas-flowed microchannel, and (iii) the droplet jumping upon coalescence on superhydrophobic surface; in particular for the parameters like hydrophobicity surfaces, droplet sizes, numerical methods, channel sizes, wall conditions, popular references and boundary conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.890-896
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• 2010

Increasing styling features for automotive headlamps speed up the focus of understanding condensation at inner surfaces. Water vapor condensation on the inside surface of the headlamp lens is an essential factor that affects secure front view and headlamp life. One of the headlamps of automobile which is one of the most popular in Korea was chosen for the present analysis. In the basis of the experimental data of automobile given by a manufacturer, boundary conditions were defined and free convection of the air inside the headlamp and radiation from the bulb to the other surfaces are considered. As a result, temperature distribution of the inside surface of the headlamp lens are approximately the same as the experimental result.

• Journal of Industrial Technology
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• v.34
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• pp.39-43
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• 2014

This paper represents a highly porous MWCNT film electrode with interconnected open pores and demonstrated the possibility of using an MWCNT network film as the top electrode for polyimide capacitive humidity sensors. Polyimide humidity sensors with MWCNT electrodes exhibited about 6 times faster response than equivalent Cr electrode sensors. This result may be due to their percolated pore structures, which make water molecules accessible to all polyimide surfaces. The much faster response times of MWCNT electrode sensors is attributed to the percolated pore network, which allows more water molecules to be accessible to polyimide surfaces.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.17-22
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• 1991

The purpose of this study was to evaluate the tensile bond strengths of treated alloy surfaces for resin bonded retainers. For the experiment metal surfaces of 5 alloys were teated with sandblasting, Silicoating Rocatec, and cemented with Visio-Gem. All specimens divided into two groups. The group I specimens were treated with 24-hour immersion in $37^{\circ}C$ distilled water, and group II specimens were teated with 1500 thermo-cycles from $5^{\circ}C\;to\;55^{\circ}C$. The obtained results were as follows: 1. Bond strength values showed significantly different between sandblasting group and other groups after a 24-hour immersion in $37^{\circ}C$ distilled water(P<0.05). 2. All samples were fractured during thermo-cycles for sandblasting group, and bond strength values for Silicoating and Rocatec groups showed significantly different after 1500 thermo-cycles from $5^{\circ}C\;to\;55^{\circ}C$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.8
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• pp.671-675
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• 2002

The gas adsorption efficiency for various surfaces with three different characteristics has been reviewed. The dimethyl disulfide gas has been used to investigate characteristics of gas adsorption for different surface characteristics such as plasma treated, lacquer coated and untreated. Three different surfaces were evaluated in dry conditions initially and tested at wet surface conditions with spraying water to evaluate the gas adsorption efficiency which usually occurred at defrost cycles. The results show that the gas adsorption of the plasma treated sample has better performance than others. The lacquer coated and untreated samples showed the similar result, but the lacquer coated sample showed a slightly better performance.

• Applied Microscopy
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• v.46 no.4
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• pp.201-205
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• 2016

Functional surfaces in nature have been continuously observed because of their ability to adapt to the environment. To this end, methods such as scanning electron microscopy (SEM) have been widely used, and their wetting functions have been characterized via environmental SEM. We investigated the superhydrophobic hairy leaves of Pelargonium tomentosum, i.e., peppermint-scented geranium. Their surface features and wettability were studied at multiple-scales, i.e., macro-, micro-, and sub-micro scales. The surfaces of the investigated leaves showed superhydrophobicity at the macro-, and micro-scales. The wetting or condensing behavior was studied for molecule-size water vapors, which easily adhered to the hairy surface owing to their significantly lower size in comparison to that of the surface.

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.13-17
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• 1991

The preparation and characterization of semiconductive electrodes of MgO doped $Fe_2O_3$ were investigated. Pellets of MgO doped $Fe_2O_3$ were sintered at high temperatures between 1300$^{\circ}$C and 1400$^{\circ}$C and quenched rapidly in distilled water. The surfaces were analyzed by X-ray diffraction and scanning Auger electron spectroscopy. The surfaces of pellets contained both corundum structure ($Fe_2O_3$) and spinel structure ($Mg_xFe_{3-x}O_4$). Electrodes made of this material gave comparable anodic and cathodic photocurrents under illumination. The cathodic and anodic photocurrent on these photoelectrodes were verified high at 5-10 wt. percent that is critical doping amounts.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.394-401
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• 2019

The failure of steam generators (SGs) due to corrosion is one of the most important problems in power plants. Impurities usually accumulate in the hot sides of SG and form deposits on the SG surfaces. In this paper, the sensitivity analysis of the accumulation of water impurities in the heat exchangers of nuclear power plants is presented. The convection-diffusion equation of the liquid phase on the heated surfaces is derived and then solved by the finite volume method. Also, the effects of the thermal-hydraulic parameters in the form of dimensionless numbers, such as $Pe_q$, $Pe_u$, $k_q$(relative solubility of impurity between the steam and water) on the impurities concentration are studied.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.158-161
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• 1987

A Series of hydrophilic-hydrophobic copolymeric surfaces of 2-hydroxyethyl methacrylate (HEMA) and various alkyl methacrylate (RMA) have been prepared by in-situ solution copolymerization using a redox radical initiator. Contact angles of various probing fluids on the polymeric surfaces were determined in air (hydrophobic environment) and under water (hydrophilic environment). From contact angle data, the dispersive interaction contribution (${\gamma}^d_s$) and the polar contribution (${\gamma}^p_s$) to the total surface free energy (${\gamma}^d_s$) and interfacial energetic quantities (e.g., water-polymer, liquid-polymer interface, etc.) were estimated by surface and interface physicochemical theory. From the comparison of surface energetic components between hydrophobic and hydrophilic media, it is found that surface and interface energetic components of polymeric surface as a representative low-energy surface are highly dependent on environmental fluids. Also, from the correlation between interfacial energetic results and surface energetic criterion of biocompatibility, we found that HEMA/BMA, HEMA/HMA copolymer systems are in the region of biocompatibility.

• Asian Journal of Atmospheric Environment
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• v.7 no.1
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• pp.1-7
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• 2013

To establish the method for investigating the behavior of aerosol particles deposited on the leaf surface against fog water under natural conditions, scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) analysis and wash water analysis by ion chromatography after the washing treatment were performed using leaves of white birch collected from low part of the tree crown and the top of the tree in Sapporo City, Hokkaido, northern Japan. Each of collected leaves was divided into two parts according to the treatment performed: leaf surface (adaxial side) was 1) untreated, and 2) washed with deionized water with a pipette. In untreated samples, many particles of various shapes, including soil particles and organic debris, were deposited on the surface. Particles containing S were found on the surface of samples collected from only low part of the tree crown. After the washing treatment, SEM-EDX analysis revealed that soil particles and particles containing S had been washed off with water, although some particles such as soil particles and organic debris still remained on the leaf surface. The major anion such as $SO{_4}^{2-}$ was detected in wash water of all samples, although the peak of S in X-ray spectra was not detected from samples collected at top of the tree. The combination of SEM-EDX analysis with wash water analysis indicated that $SO{_4}^{2-}$ was deposited on the leaf surface in dissolved state and/or in state of submicron particles. These results suggested that fog water could remove soil particles and particles containing S and $SO{_4}^{2-}$ from the leaf surfaces, but not all particles. There was no difference in sampling position in the tree crown. Our study suggested that combination with SEM-EDX analysis and wash water analysis would be effective for investigation of the behavior of particles on the leaf surface against fog water.