• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1317-1321
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• 2007

Aluminized steel sheet that Al coated on low carbon steel has a excellent heat resistance, thermal reflection and corrosion resistance. It has applied to fuel tank, automotive exhaust systems, etc. Laser weldability of the aluminized steel for the full penetration welding will be described in this paper. We focused on the effect of Al coating conditions on weld strength. For these objectives, aluminized steel sheets that has various thickness and coating weight were prepared for laser welding. And then, tensile-shear and hardness test were carried out. At that same time, Al content mixed in weld after laser welding was evaluated and investigated a correlation between the mixed Al and mechanical properties. Besides, as removing partially coating layer, weldability has been investigated according to position of coating layer. As a result of this study, as increasing Al content in weld, tensile-shear strength was decreased. Also it was identified that Al of coating layer caused grain growth.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.189-199
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• 2009

The Powder characteristics and sintering behavior of $SiO_2$ coated $BaTiO_3$ were studied. $BaTiO_3$ powders were synthesized by the liquid mix method developed by Pechini, and silica coating was prepared by alkoxide hydrolysis method with TEOS and ethanol. The particle size of the $BaTiO_3$ powders was 35 nm and the thickness of the $SiO_2$ coating layer was 5 nm. As the $SiO_2$ content increased, the $SiO_2$ layers improved the powder dispersion by increasing electrostatic repulsion between the $BaTiO_3$ particles. Effects of MgO coating on microstructure and dielectric properties of $BaTiO_3$ have been studied compared with mechanically MgO mixed $BaTiO_3$. MgO coated $BaTiO_3$ particles were prepared by a homogeneous precipitation method using $MgCl_2\cdot 6H_2O$ and urea. MgO coated $BaTiO_3$ exhibited homogeneous microstructure compared with mixed samples. XRD analysis revealed that Mg substitution for the Ti site in the MgO mixed sample was much greater than in the coated one. Electrical properties of MgO mixed and coated $BaTiO_3$ were affected by the diffusion behavior of Mg in $BaTiO_3$ lattice.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.16 no.1
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• pp.27-35
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• 2006

The aim of this study was to identify the sources of benzene detected in airborne of casting workplace where benzene was not used as raw material. We have identified benzene by GC/FID and GC/MSD. In this pilot test, small size iron chamber(diameter 30 cm, height 20 cm) was used. As the raw materials, new sand, recovered sand, and mixed casting sand(new sand + solidifying agent + organic resin + coating material) was tested, respectively. In the new sand benzene was not detected, but in the recovered sand and the mixed casting sand was detected. Xylenesulfonic acid(solidifying agent), one of the mixed casting sand ingredients was thought to product benzene by thermal decomposition above $400^{\circ}$..., but the other raw materials(organic resin and coating material) were thought not to product benzene. In this experiment, the most of benzene by thermal decomposition was produced within 1 hour after pouring the iron solution($1560^{\circ}$...) in small size iron chamber. When the mixed casting sand with coating material was used, the concentration of the produced benzene was average 2.91 ppm(range 1.98~3.72 ppm), and without coating material, benzene concentration was average 0.11 ppm(range 0.08~0.14 ppm).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.4
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• pp.1-7
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• 2013

Optical characteristics including the view angle and color temperature uniformity of LED packages with an integrated lens fabricated by compression molding method are investigated according to lens shape, lens materials, and phosphor coating methods. Four types of lens shape are designed and their optical output power dependence on the refractive index of silicone encapsulant are evaluated. Also, spatial color temperature uniformities of packages fabricated with different phosphor coating methods-direct coating on a chip vs. uniformly mixed with silicone encapsulant- are compared at various view angles. As the result, it is found that phosphor coating method is more effective on color temperature uniformity than lens shape. The maximum color temperature difference of a package with direct coating of phosphor on a chip is 1,340K according to the view angle at the color temperature of 5,000K, and that of a package with uniformly mixed phosphor is 250K, which indicates 1,090K improvement of color uniformity for the latter case.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.79-83
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• 2018

An accurate method to measure shielding effectiveness(SE) of EMI spray coating film is presented. After high frequency simulating, Circular coaxial standard test fixture is fabricated. A sample of EMI spray coating film was fabricated for insertion into a circular coaxial standard test fixture. The measuring instrument used an Agilent 8722ES vector network analyzer for the SE measurement. The exact SE of copper and silver mixed spray coating sample was measured by the composition of the measuring instrument and the measuring sample. The SE of copper sample was measured at 70 dB and the SE of copper and silver mixed spray coating sample was measured at 60 dB. As a result of the measurement, the reliability of the circular coaxial standard test fixture was confirmed.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1930-1932
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• 2005

Colloidal Silica(CS)/methyltrimethoxy silane(MTMS) and CS/MTMS/epoxy silane(Es) sol solutions were prepared in variation with synthesizing parameters such as kinds of CS, kinds of silane and reaction time. In order to understand its physical and chemical properties, sol-gel coating films on glass were fabricated. In the case of CS/MTMS sol, the coating films had high contact angle and more enhanced flat surface than those in the case of CS/MTMS/ES sol. Also, the coating films obtained from single CS had a better flat surface than those obtained from mixed CS. In the case of thermal stability, thermal dissociation of CS/MTMS and CS/MTMS/ES sol-gel coating films did not occur up to $550^{\circ}C$ and $440^{\circ}C$ respectively. The thickness of coating films obtained from CS/MTMS sol increased than those of CS/MTMS/ES sol. In addition, the coating films obtained from single CS were more thicker than those obtained from mixed CS.

• Journal of Powder Materials
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• v.26 no.5
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• pp.421-431
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• 2019

In this study, the formation, microstructure, and wear properties of Colmonoy 88 (Ni-17W-15Cr-3B-4Si wt.%) + Stellite 1 (Co-32Cr-17W wt.%) coating layers fabricated by high-velocity oxygen fuel (HVOF) spraying are investigated. Colmonoy 88 and Stellite 1 powders were mixed at a ratio of 1:0 and 5:5 vol.%. HVOF sprayed self-fluxing composite coating layers were fabricated using the mixed powder feedstocks. The microstructures and wear properties of the composite coating layers are controlled via a high-frequency heat treatment. The two coating layers are composed of ${\gamma}-Ni$, $Ni_3B$, $W_2B$, and $Cr_{23}C_6$ phases. Co peaks are detected after the addition of Stellite 1 powder. Moreover, the WCrB2 hard phase is detected in all coating layers after the high-frequency heat treatment. Porosities were changed from 0.44% (Colmonoy 88) to 3.89% (Colmonoy 88 + ST#1) as the content of Stellite 1 powder increased. And porosity is denoted as 0.3% or less by inducing high-frequency heat treatment. The wear results confirm that the wear property significantly improves after the high-frequency heat treatment, because of the presence of well-controlled defects in the coating layers. The wear surfaces of the coated layers are observed and a wear mechanism for the Ni-based self-fluxing composite coating layers is proposed.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.63-70
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• 1995

A crack-free ceramic composite membrane with micropores has been synthesized by the pressurized sol-gel coating technique using the mixed Al2O3-SiO2 sols. The mixed sols were prepared by mixing nanoparticulate SiO2 and boehmite sols. These sols were more stable at lower pH, but very unstable when their copositions were in the range of 50~75mol% of SiO2 at the same pH. The mixed Al2O3-SiO2 membrane prepared from the mixed sol (0.2mol/$\ell$ of solid content and pH=2) containing 40mol% of SiO2 had the mean pore radius of 0.80nm and the specific surface area of 280$m^2$/g. The nitrogen permeability through the coated Al2O3-SiO2 layer was 42$\times$107mol/$m^2$.s.Pa. It was found that the thermal stability of aluminosilicate membranes, even through similar to that of SiO2 membranes, was much improved in comparison with ${\gamma}$-alumina membranes.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.2
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• pp.113-119
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• 1987

This experiment was carried out in laboratory to find out the effect of coating materials, minerals and insecticides on germination of pasture seed. Seed coating was made by specially made machine and seed germination in petridishes was also determined from Sep. 1986 to May 1987. The results were summarized as follows; 1. Coating seed gave bad germination compared with the control. There were significant difference between treatment, coating materials and adhesives in white and red clover while Phleum pratense germination was improved by coating materials. 2. In mineral coating treatments, on Mg alone or Mg mixed treatment, germination was deepressed. Generally germination was lowed by mineral treatment, but the difference was small. 3. Uncoating treatment with insecticide was superior to coating treatment in terms of germination. Among the insecticide Ballen gave more serious effect to seed germination.

• Textile Coloration and Finishing
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• v.22 no.3
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• pp.239-245
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• 2010

Breathable waterproof PET fabrics were prepared by the UV coating of UV-curable polyurethaneacrylate(PUA) formulation mixed with polyethyleneglycol(PEG) as a water soluble pore former. The dispersed PEG in the UV-cured coating was extracted by warm water, which can generate individual circular pores uniformly distributed all over the coating instead of pore channels. Accordingly the moisture permeability of the microporously coated fabrics increased substantially with increasing PEG addition without significant reduction of hydrostatic pressure. Also the silicone diacrylate addition in the formulation was beneficial in increasing the hydrostatic pressure. The UV-based microporous coating can be an alternative to conventional thermal curing of solventborne polyurethane coating owing to the enhanced environment friendliness and energy saving.