• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.235-239
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• 2002

The objective of the experiment is to investigate the effect of microstructures of gray cast iron oil wear characteristics of automotive disc brakes. Six different gray cast iron rotors were manufactured by changing carbon equivalent and cooling rate. The change of DTV (disc thickness variation) before and after wear tests was measured to examine the wear properties according to the microstructures of gray iron discs since the DTV generation is caused by the circumferential uneven wear. Experimental results showed that the morphology of graphite flake and hardness in gray cast iron were crucially associated with the change of DTV. In particular, the DTV changes of rotor decrease when the length and area fraction of graphite flake in brake rotors increase and hardness of brake discs reduces.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.222-227
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• 2017

Flake-type micro hollow silica was synthesized by precipitation method using an $Mg(OH)_2$ inorganic template and sodium silicate and ammonium sulfate as the silica precursors. We investigated the effects of the silica precursor concentration on the shape, shell thickness, and surface of the hollow silica. When the concentration of the silica precursor was 0.5 M, the hollow silica had a smooth and translucent thin shell, but the shell was broken. On the other hand, the shell thickness of the hollow silica changed in the range of 12 nm to 18 nm with the increase of the precursor concentration from 0.7 M to 1.1 M. Simultaneously, unintended spherical silica satellites were created on the shell surface. The number of satellites and the size rose according to the increased concentration of silica precursor. The reason for the formation of spherical silica satellites is that the $NH_4OH$ nucleus generated in the synthesis of hollow silica acted as another silica reaction site.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.80-86
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• 2024

Polyimide has advantages that are different with other polymers, such as high thermal stability, heat resistance, and high chemical resistance. Various application methods for Polyimide have been studied. In this study, research was conducted to manufacture Polyimide films. While implementing Polyimide films with excellent adhesion and pencil hardness through optimized manufacturing conditions, the applicability as a packaging material was considered by adding glass flakes to reduce oxygen permeability. As a result, Polyimide films with glass flakes and (3-Aminopropyl)triethoxysilane have a thickness of about 50 ㎛ were uniformly implemented, and it was confirmed that the adhesion of Polyimide films was 4B, pencil hardness was 5H, and oxygen permeability was below 8.795 × 10^-9 cc/s, respectively.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.216-219
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• 1987

Dielectric and Mechanical Properties of Mica flake/ Epoxy Composite are investigated. The Mica content is about 50 wt % and its thickness is about $240{\mu}m$. The finished Mica flake/Epoxy Composite contains about 0.1-1.0 wt % of aminosilane coupling agent. Ruby Mica filler and high temperature curing Epoxy resin are used. From the viewpoint of dielectric and mechanical properities. the optimum properties is obtained for the sample post cured at $130^{\circ}C$ for 5 h ours after curing at $80^{\circ}C$ for 2 hours and with 0.5 weight % silane coupling agent.

• Applied Microscopy
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• v.42 no.2
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• pp.87-93
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• 2012

In this study, fine structures of silica, titanium dioxide, talc and kaolin used in decorative cosmetics and the mixture extracted from BB cream cosmetics were observed by scanning electron microscopy. Kaolin had plate like shape structures of polygon with smooth surface and edge of kaolin had a relatively smooth appearance in comparison with talc. Also, thickness of each layer was estimated to about $0.1{\mu}M$ in the lump formed in stratum of several layers. Talc was observed by lumps shape phase of layering very thin flake. Boundary of thin flake was sharp or angular phase and thickness of flake was approximately 600 nm in diameter. When comparing the thickness of kaolin and talc, we was confirmed that kaolin was thicker than talc. Diameter of titanium dioxide was estimated to 0.2~0.3 ${\mu}M$ and surface of particle was a soft cubic form. Silica was confirmed that variety of size from 200 nm to $15{\mu}M$ of globular shape was measured. From the observation of inorganic pigments, silica was homogeneous dispersed in the BB cream cosmetics and among each other was filled with relatively small size like talc, kaolin, titanium dioxide and iron oxide. In conclusion, we suggest that silica at decorative cosmetics were formed in cosmetic coat at the skin as the minimum thickness.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.866-872
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• 2009

The effects of magnetic powder thickness on electromagnetic wave absorption characteristics in Fe-6.5Si-0.9Cr (wt%) alloy flakes/polymer composite sheets available for quasi-microwave band have been investigated. The atomized FeSiCr powders were milled by using attritor for 12, 24, and 36 h, powder thickness changed from $40{\mu}m$ to $3{\mu}m$ upon 36 h milling. The composite sheet, including thinned magnetic flakes, exhibited higher power loss in the GHz frequency range as compared with the sheets having thick flakes. Moreover, both the complex permeability and the loss factor increased with the decrease in thickness of the alloy flakes. Therefore, the enhanced power loss property of the sheets containing thin alloy flakes was attributed to the flakes of high complex permeability, especially their imaginary part. Additionally, the complex permittivity was also increased with the reduction of flake thickness, and this behavior was considered to be helpful for improvement of the electromagnetic wave absorption characteristics in the composite sheets, including thin alloy flakes.

• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.115-119
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• 2008

The raw materials of permalloy were processed the ball-mill for 30 hours and the shape of permalloy particles was changed from sphere to flake type, which was observed using scanning electron microscope. The complex permittivity and permeability spectra and reflection loss of permalloy-rubber composite was measured using Network Analyzer in order to investigate the relationship between the microwave absorption and the material constants. The flake type permalloy-rubber composite showed high reflection loss, which was due to the high complex permittivity and permeability. Also, the matching frequency shifted toward lower frequency range with microwave absorber thickness, and the maximum reflection loss of -6.1 dB was observed in $1.65\;GHz{\sim}1.86\;GHz$ for a 1.3 mm thickness.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1213-1214
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• 2006

The synthesis of silver coated iron base alloy (Sendust : Fe-Si-Al) powder having the both effects of shielding and suppressing of electromagnetic wave was studied. Depending on thickness of silver coating layer, the electromagnetic properties of the dispersed particles complexed with organic binder were examined. It is proposed that the silver coated sendust flake powders with controlled electrical properties and thickness can be used as thin microwave absorbers in quasi-microwave frequency band.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.157-162
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• 2016

Porous $Co(OH)_2$ nano-flake thin films were prepared by a potential-controlled electro-deposition technique at various deposition voltage (-0.75, -1.0, -1.2, and -1.4 V) on Ti-mesh substrates for supercapacitor application. The potential of electrode was controlled to regulate the film thickness and the amount of $Co(OH)_2$ nano-flake on the titanium substrate. The film thickness was shown to reach the maximum value of $34{\mu}m$ at -1.4 V of electrode potential, where 17.2 g of $Co(OH)_2$ was deposited on the substrate. The specific discharge capacitances were measured to be 226, 370, 720, and $1008mF\;cm^{-2}$ in the 1st cycle corresponding to the films which were formed at -0.75, -1.0, -1.2, and -1.4 V of electrode potentials, respectively. Then the discharge capacities were decreased to be 206, 349, 586 and $866mF/cm^{-2}$, where the persistency rates were 91, 94, 81, and 86%, respectively.

• Journal of the Korean Wood Science and Technology
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• v.22 no.3
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• pp.17-25
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• 1994

This study was carried out to compare the properties of Com-Ply Boards with those of OSBs. These two kinds of boards were made of same flakes. Com-Ply Boards were covered with three different thickness veneers, such as 4mm, 3mm, and 2.5mm. All manufactured Com-Ply Boards and OSBs were 12mm thick. In MOR, all Com-Ply Boards were higher than OSB, and especially 3mm-veneer and 2.5mm-veneer Com-Ply Board were highest. But OSB showed 420kg/$cm^2$. 3mm-veneer Com-Ply Board showed the highest internal bonding 7.0kg/$cm^2$ and then 2.5mm-veneer showed 6.8kg/$cm^2$, and OSB showed 6.6kg/$cm^2$. Screw holding strength showed the high value 23.9kg/$cm^2$, 25.5kg/$cm^2$, and 29.3kg/$cm^2$ respectively at 3mm-veneer, 2.5mm-veneer Com-Ply Board and OSB. Thickness swelling of Com-Ply Boards was lower than that of OSB, but Water absorption of OSB was lower. Finally it was very encouraging that all properties of OSB without veneer, whose cost is higher than flake and whose properties is better, were not worse than those of Com-Ply Board with veneer. It seems That more researches on OSB will be required.