• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.851-856
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• 2002

Tribological behavior of plasma-sprayed $Cr_2O_3$-based coatings containing $MoO_3$ at 450$^{\circ}C$ was investigated to understand the influence of $MoO_3$. A reciprocal disc-on-plate type tribo-tester was employed to examine fricition and wear behavior of the specimens. The microstructure and phase composition of the coating was characterized with Transmission Electron Microscopy(TEM). The TEM analysis indicated that $MoO_3$ was dispersed into the grain boundary, resulting in the increase of the hardness and density of the coating. Worn surfaces were investigated by scanning electron microscopy and chemistry of the worn surfaces was analyzed using a X-ray Photoelectron Spectrometer(XPS). The results showed that the friction coefficient of the $MoO_3$-added coatings was lower than that without $MoO_3$ addition. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with $MoO_3$ composition in the protecting layer appears to be more favorable in reducing the friction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.20-29
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• 2022

In this study, in order to improve the durability of the cement composite printed with the ME type 3D printer, PDMS, sodium silicate, and a surface hardener were employed. Post-treatment was performed on 3D-printed cement composite by coating after immersion, and the degree of improvement in durability was evaluated. As a result, in all evaluations, the durability performances of the post-processed specimens were improved compared to those of the plain specimens. Water absorption resistance, chloride penetration resistance, and carbonation resistance of the PDMS treated specimens were improved by 36.3 %, 77.1 %, and 50.4 % when compared to plain specimens. Freeze-thaw resistance of the specimens treated with sodium silicate was found to be the most excellent, with an average enhancement of 47.5% compared to plain specimens. It was found that PDMS was the most efficient post-treatment materials for 3D-printed cement composite. However, as suggested in this study, the post-treatment method by coating after immersion may not be applicable to cement composite structures printed with a 3D printer in field. Therefore, a follow-up study needs to be preformed on the durability enhancing materials suitable for 3D printing.

• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.256-263
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• 2010

A Crofer 22 APU mesh coated with a conductive ceramic material was developed as an alternative cathode current collector to Ag-based materials for solid oxide fuel cells. $(La_{0.80}Sr_{0.20})_{0.98}MnO_3$ (LSM) layer was deposited onto the Crofer mesh using a spray-coating technique, in an attempt to mitigate the degradation of electrical properties due to surface oxidation at high temperatures. The oxidation experiments at $800^{\circ}C$ in air indicated that the areaspecific resistance (ASR) of the LSM-coated Crofer mesh was strongly dependent on the wire diameter and the contact morphology between mesh and cell. In addition, the post-heat-treatment in $H_2/N_2$ resulted in a reduced thickness of Cr-containing oxide scales at the interface between Crofer mesh and LSM layer, leading to a decreased ASR.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.9-15
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• 2010

Recently, the high-compressive strength concrete where the use is extending was weak in fire because of spalling that was occurring with rise of internal vapor pressure by high temperature. For preventing spalling of high-strength concrete in fire, Organic fibers have been using in concrete generally. By melting of organic fibers in concrete in fire, the internal moistures of concrete moves quickly to the outside, and so, preventing of spalling of high-strength concrete. But this method will be able to prevent the spalling of high-strength concrete, but makes the decrease of the concrete strength after fire. This study make a comparison between properties of preventing of spalling and remaining compressive strength of concrete using intumescence Alkali-Silicates fire-resistant material and that of concrete with organic fibers. Using organic fibers for preventing of spalling of concrete are P.P and Nylon fibers, and anti-fire intumescence material for protection of concrete surface is alkali-silicate materials. Fire resistance test executed as long as 3 hr under the flame temperature $1,200^{\circ}C$ over. In the case of concrete with P.P fibers, don't occurred the spalling, but the remaining compressive strength will not be able to measure, the concrete using intumescence Alkali-Silicates system fire-resistant material is not only preventing of the spalling but also the remaining compressive strength maintained until the maximum 96%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.851-856
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• 2003

We have investigated the material and electrical properties of $Bi_{4-x}La_xTi_3O_{12}$ (BLT) ferroelectric thin film for ferroelectric nonvolatile memory applications of capacitor type and single transistor type. The 120nm thick BLT films were deposited on $Pt/Ti/SiO_2/Si$ and $SiO_2/Nitride/SiO_2$ (ONO) substrates by the sol-gel spin coating method and were annealed at $700^{\circ}C$. It was observed that the crystallographic orientation of BLT thin films were strongly affected by the excess Bi content and the intermediate rapid thermal annealing (RTA) treatment conditions regardeless of two type substrates. However, the surface microstructure and roughness of BLT films showed dependence of two different type substrates with orientation of (111) plane and amorphous phase. As increase excess Bi content, the crystallographic orientation of the BLT films varied drastically in BLT films and exhibited well-crystallized phase. Also, the conversion of crystallographic orientation at intermediate RTA temperature of above $450^{\circ}C$ started to be observed in BLT thin films with above excess 6.5% Bi content and the rms roughness of films is decreased. We found that the electrical properties of BLT films such as the P-V hysteresis loop and leakage current were effectively modulated by the crystallographic orientations change of thin films.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.142-149
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• 2020

In this study, the electrochemical performance of Graphite/Silicon/Pitch composites as anode material was investigated to improve the low theoretical capacity of artificial graphite. Spherical artificial graphite surface was coated with polyvinylpyrrolidone (PVP) amphiphiles material to synthesize Graphite/Silica material by silica islands growth. The Graphite/Silicon/Pitch composites were prepared by petroleum pitch coating and magnesiothermic reduction. The Graphite/Silicon/Pitch composite electrodes manufactured using poly(vinylidene fluoride) (PVDF), carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) binders. The coin type half cell was assembled using various electrolytes and additives. The Graphite/Silicon/Pitch composites were analysed by X-ray diffraction (XRD), scanning electron microscope (SEM) and a thermogravimetric analyzer (TGA). The electrochemical characteristics of Graphite/Silicon/Pitch composite were investigated by constant current charge/discharge, rate performance, cyclic voltammetry and electrochemical impedance spectroscopy. The Graphite/Silicon/Pitch composites showed high cycle stability at a graphite/silica/pitch ratio (1:4:8 wt%). When the electrode is prepared using PAA binder, the high capacity and stability is obtained. The coin type half cell assembled using EC: DMC: EMC electrolyte showed high initial capacity (719 mAh/g) and excellent cycle stability. The rate performance has an capacity retention (77%) at 2 C/0.1 C and an capacity recovery (88%) at 0.1 C / 0.1 C when the vinylene carbonate (VC) was added.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.224-233
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• 2016

Embedded Railway Systems (ERS) will be adapted for wireless trams and will be constructed along city roadways. An asphalt layer should be overlaid on top of the concrete slab used as the trackbed structure in order to ensure smoothness and surface levels equal to those of existing road pavement in downtown city areas. However, the characteristics of an asphalt layer when used as overlay pavement for an ERS are complicated and the behavior of this material is not yet well defined and understood. Therefore, in this study, laboratory shear and tensile bond strength tests were conducted to investigate the bonding behavior of an asphalt layer in a multilayered trackbed section of an ERS. For the laboratory tests, a waterproof coating material was selected as a bonding material between the asphalt overlay and a concrete specimen. Valuable design parameters could be obtained based on the tensile and shear bond strength test results, providing information about the serviceability and durability of the overlaid pavements to be constructed alongside the ERS for wireless trams. In addition, a deformation analysis to assess the tensile strain generated due to truck axle loads at the interface between the asphalt layer and the concrete slab was conducted to verify the stability and performance of the asphalt layer.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.1
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• pp.39-47
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• 2024

In this study, LiDAR-detective black material is synthesized by recycling silicon sludge (SS) that is generated from semiconductor manufacturing process, and its recognition is confirmed using two types of LiDAR sensors (MEMS and Rotating LiDAR). In detail, metal impurities on the surface of SS is removed, followed by coating of titanium dioxide (TiO₂) and subsequent chemical reduction to obtain SS-derived black TiO₂ (SS/bTiO₂) material. As-prepared SS/bTiO₂ is mixed with transparent paint to prepare hydrophilic black paints and applied to a glass substrate using a spray gun. SS/bTiO₂-based paint shows similar blackness (L^*=15.7) compared to commercial carbon black-based paint, and remarkable NIR reflectance (26.5R%, 905nm). Furthermore, MEMS and Rotating LiDAR have successfully detected the SS/bTiO₂-based paint. This is attributed to the occurrence of high reflection of light at the interface between the black TiO₂ and the silicon sludge according to the Fresnel's reflection principle. Hence, the new application field to effectively recycle silicon sludge generated in the semiconductor manufacturing process has been presented.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.83-87
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• 2010

We present here the effect of extracellular matrix (ECM) on the proliferation and physiology of HL-1 cardiac cells. HL-1 cell is from AT-1 mouse atrial cardiomyocyte tumor lineage. HL-1 cell can be serially passaged, yet they maintain the ability to contract which is a promising character of HL-1 cell for the cell based biosensors. HL-1 cells grow up on the ECM which can affect on the attachment and growth of HL-1. In this paper, we discuss HL-1 cell-ECM interactions with three different ECMs and non-treated surface. HL-1 cells are grown for 4 days after seeding then observed their attachment. Also they were immunostained by hoechst and EthD-1 for proliferation, phalloidin for Factin, and DAPI for nuclei. Fibronectin was revealed as the proper ECM material for HL-1 cell culture. This study can provide basic information for understanding the cell-ECM interactions and growth of HL-1 cells.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.175-182
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• 2008

This study is concerned with the evaluation of the corrosion resistance of coated semiconductor equipment parts with various processes. To select the appropriate basis for evaluation, replacement parts were observed during the semiconductor manufacturing process. This study also ran a dry corrosion test using $Al_2O_3$, which is mostly used as a coating material. This test quantitatively measured the efficiency of coated parts. Surface morphology, leakage current and breakdown voltage were also evaluated. This study showed that a dry corrosion process led to the drop of electrical properties, for example, the leakage current increase and the dielectric strength decrease. The surface morphology test displayed that surface damage is largely dependent on the exposure time to corrosive environments. By using the values that changed during the corrosion process, it may be possible to contrive a method to evaluate the efficiency of coated parts with various processes.