• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.319.1-319.1
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• 2013

Solid oxide fuel cells (SOFCs) have been recognized as one of emerging renewable energy sources, due to minimized pollutant production and high efficiency in operation. The performance of SOFCs is largely dependent on the electrode polarization which involves the oxidation/reduction in cathodes and anodes along with the charge transport of ions and electronic carriers. Atomic layer deposition is based on the alternate chemical surface reaction occurring at low temperatures with high uniformity and superior step coverage. Such features can be extended into the coating of metal oxide and/or metal layer onto the porous materials. In particular, the atomic layer deposition is can manipulated in controlling the charge transport in terms of triple phase boundaries, in order to control artificially the electrochemical polarization in electrodes of SOFC. The current work applied atomic layer deposition of metal oxides intro the electrodes of SOFCs. The corresponding effect was monitored in terms of the electrochemical characterization. The roles of atomic layer deposition in solid oxide fuel cells are discussed towards optimized towards long-term durability at intermediate temperature.

• Journal of the Korean Applied Science and Technology
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• v.20 no.1
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• pp.8-19
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• 2003

Environmental friendly acrylics/urea high-solid paints (BEHCU) were prepared through the curing reaction of acrylics resin(BEHC) containing 70wt% of solids content and butylated urea curing agent. BEHC was synthesized by addition copolymerization of caprolactone acrylate(CLA), 2-hydroxypropyl methacrylate(2-HPMA), ethyl methacrylate, and n-butyl acrylate. The addition polymerization of these monomers, especially including flexible CLA monomer and 2-HPMA monomer with OH funtional group, under appropriate reaction conditions resulted in polymers with controlled glass transition temperature($T_g$) and crosslinking density. The molecular weight($M_w$) of these polymers(BEHCs) was 2940${\sim}$3240 and polydispersity ($M_w/M_n$) was in the range of 1.61${\sim}$1.72. The viscosity and the molecular weight of these acrylic resins increased with increasing $T_g$. The coated films were prepared using curing reaction between BEHC resin and butylated urea curing agent at 100$^{\circ}C$ for 30 minutes. Our experimental resulted showed that enhancement of the coating properties such as adhesion, flexibility, impact resistance, water resistance, and abrasion resistance could be expected through introducing CLA component in acrylic resin for the high-solid content acrylics/urea coatings.

• Journal of the Korean institute of surface engineering
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• v.36 no.4
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• pp.291-295
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• 2003

Many steam turbine components encounter solid particle erosion damage. It has been reported that particle erosion damage is caused by oxide scale exfoliation from boiler tubes. One of the most effective solutions to combat the erosion damage is the application of erosion resistant coatings on the turbine components. In this study, particle erosion resistance for various hard coatings such as nitride, Cr carbide and boride coatings was evaluated under the simulated erosion conditions of steam turbines. Based on the particle erosion tests, the boride coating was found to be more superior to others.

• Tribology and Lubricants
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• v.37 no.3
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• pp.106-111
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• 2021

There are several studies on reducing the friction that occurs on the relative sliding contact surface of moving parts under extreme environments. In particular, a solid lubricated bearing is studied to solve the tribological problem with friction reduction and durability parts using solid lubricants (lead or silver) in a vacuum atmosphere. Galinstan is mainly used as a liquid metal lubricant, but it is inevitable to have limited tribological applications owing to its high coefficient of friction. Many researchers work on surface texturing for surface modification and precision processing methods. To increase durability and low friction, DLC coating with hydrophobicity is applied on the contact surface texture. Therefore, using an untextured specimen, a dimple specimen, and a DLC-coated dimple specimen under liquid metal lubrication, this paper presents the following experimental sliding friction characteristics in the sliding friction test. 1) The average coefficient of friction of the DLC-coated dimple specimen and dimple specimen are lower compared to that of a non-patterned specimen. 2) In the DLC-coated dimple specimens, the average coefficient of friction changes according to the change in the dimple density. 3) DLC-coated dimple specimens with a density of 12.5 have the lowest average coefficient of friction under 41.6 N of normal load and 143.3 RPM.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.21-27
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• 1996

The effects of various manufacturing conditions on the characteristics of metal particle tape using ultra-fine metal powder were investigated. As functions of kneading conditions and milling solid contents. coating thickness, orientation, calender and curing conditions. various properties of the tapes were studied. By the consideration of physical and eletromagnetic properties of the tapes, optimum process conditions were determined. As a result of above investigations, we concluded that manufacturing processes were very important factor in addition to dispersion behavior of particles for achieving maximum properties of the metal particle tape.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.864-869
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• 2013

As the size of mechanical components decreases, capillary forces and surface tension become increasingly significant. A major problem in maintaining high reliability of these small components is that of large frictional forces due to capillary action and surface tension. Unlike the situation with macro-scale systems, liquid lubrication cannot be used to reduce friction of micro-scale components because of the excessive capillary and drag forces. In this work, the feasibility of using evaporation to coat a thin film of organic lubricant on a solid surface was investigated with the aim of reducing friction. Petroleum and silicone oils were used as lubricants to coat a silicon substrate. It was found that friction could be significantly reduced and, furthermore, that the effectiveness of this method was strongly dependent on the coating conditions.

• Korean Journal of Materials Research
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• v.14 no.5
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• pp.368-373
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• 2004

To improve the conventional cathode-supported tubular solid oxide fuel cell (SOFC) from the viewpoint of low cell power density, expensive fabrication process and high operation temperature, the anode-supported tubular solid oxide fuel cell was investigated. The anode tube of Ni-8mol% $Y_2$O$_3$-stabilized $ZrO_2$ (8YSZ) was manufactured by extrusion process, and, the electrolyte of 8YSZ and the multi-layered cathode of $LaSrMnO_3$(LSM)ILSM-YSZ composite/$LaSrCoFeO_3$ were coated on the surface of the anode tube by slurry dip coating process, subsequently. Their cell performances were examined under gases of humidified hydrogen with 3% water and air. In the thermal cycle condition of heating and cooling rates with $3.33^{\circ}C$/min, the anode-supported tubular cell showed an excellent resistance as compared with the electrolyte-supported planar cell. The optimum hydrogen flow rate was evaluated and the air preheating increased the cell performance due to the increased gas temperature inside the cell. In long-term stability test, the single cell indicated a stable performance of 300 mA/$\textrm{cm}^2$ at 0.85 V for 255 hr.

• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1301-1310
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• 1996

Generally it requires high sintering temperatures more than 135$0^{\circ}C$ to make semiconductive BaTiO3 ceramics. Also it is very difficult to achieve a homogeneous mixing in solid-state reaction method. Therefore the liquid phase distributed to non-uniform dilute the characteristics of PTCR. In order to improve the uniformity this study is used the sol-gel coating method. Using this method we studied the new manufacturing process that had a high reproducibility and mass production capability. Tetraethyl orthosilicate (TEOS) was used as a source of Si. The semiconductive BaTiO3 ceramics which was produced by sol-gel method for the SiO2 addition and sintered between 124$0^{\circ}C$ and 130$0^{\circ}C$ showed almost same resistivity at room temperature among 125$0^{\circ}C$ and 130$0^{\circ}C$. As the results We could be sintered the semiconducting BaTiO3 ceramics at lower temperature even at 125$0^{\circ}C$ maintaining the same specific resistivity ratio ($\rho$max/$\rho$min) at 130$0^{\circ}C$. The specific resistivity both below and above the Curie temperature were increased by slow cooling and the steepness of the plots in the reasion of transition from low to high resistance increased as the cooling rate decreased.

• Journal of Environmental Science International
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• v.30 no.12
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• pp.1041-1051
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• 2021

The purpose of this study was to identify for extenders, adhesives, colorants, and fungicides suitable for the production of high-quality film-coated seeds of Chinese cabbage. In addition, the effect of various additives used for film coating on the germination of coated seeds and seedling vigor was investigated to establish appropriate treatment conditions for film coating efficiency. The germination rate and germination speed in Chinese cabbage film-coated seeds did not differ significantly depending on the type and concentration of the extender, while the use of Talc resulted in superior granulation capacity and adhesion of the seed coat in comparison to Zeolite. There was no significant difference in the germination rate depending on the type of adhesive used for film coating of Chinese cabbage seeds, but the germination rate was slightly slower in the film-coated seeds using carboxymethyl cellulose as an adhesive. On the other hand, the seeds coated with a film using 1% PVA as an adhesive not only maintained hardness enough to withstand external pressure, but also showed a high germination rate. In addition, the suitable disinfectant for film coating was venoram, and the treatment concentration was good at 250 mg·L^-1. The type of colorant used in the film-coated seeds of Chinese cabbage did not significantly affect the germination rate, germination speed, and seedling vigor. The seeds film-coated using the liquid colorant were superior in appearance to the seeds film-coated with the solid colorant, which implies the possibility of reduction in the manufacturing costs by using the water-soluble paints as colorants for film-coated seeds.

• Microbiology and Biotechnology Letters
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• v.23 no.2
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• pp.236-242
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• 1995

Biological control of soilborne plant pathogens by the addition of antagonistic microorganisms to the soil may offer a practical supplement or alternative to existing disease management strategies that depend heavily on chemical pesticides. Soil amendment with antagonistic microbes was non-effective because of high cost, low efficacy, and inconvenient usage on the treatment course. Therefore, seed coating formulation for the application of biological seed treatments has been being to apply successful disease suppression for many important crops. The objectives of this study were to investigate the optimal condition for the spore production of biocontrol agent Bacillus subtilis YBL-7 and the liquid coating formulation that contained a suspension of a proper aqueous binder, as well as a ground fine solid particulate material. The maximum yield has been obtained from 60 hrs-old culture at 30$\circ$C in spore forming (SF) medium containing 0.8% nutrient broth, 0.05% yeast extract, 10$^{-1}$ M MgCl$^{2}$, 10$^{-4}$ M MnCl$^{2}$, 10$^{-5}$ M dipicolinic acid, and pH 6.5. The optimal condition of dried spore preparation was achieved when cells of B. subtilis YBL-7 was heat-dried with 50$\circ$C for 2 hrs.