• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.236-236
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• 2011

Silicon oxynitride (SiON) was deposited for gas barrier film on polyethylene terephthalate (PET) using octamethylycyclodisiloxane (Si4O4C8H24, OMCTS) precursor by plasma enhanced chemical vapor deposition (PECVD) at low temperature. The ion flux and substrate temperature were measured by oscilloscope and thermometer. The chemical bonding structure and barrier property of films were characterized by Fourier transform infrared (FT-IR) spectroscopy and the water vapor transmission rate (WVTR), respectively. The deposition rate of films increases with RF bias and nitrogen dilution due to increase of dissociated precursor and nitrogen ion incident to the substrate. In addition, we confirmed that the increase of nitrogen dilution and RF bias reduced WVTR of films. Because, on the basis of FT-IR analysis, the increase of the nitrogen gas flow rate and RF bias caused the increase of the C=N stretching vibration resulting in the decrease of macro and nano defects.

• Korean Journal of Optics and Photonics
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• 제20권4호
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• pp.236-240
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• 2009

LED modules, based on MCPCB with a hard barrier oxide layer and an improved thermal dissipation property, are presented. Reflecting cups were also formed on the surface of the MCPCB such that optical coupling between neighboring chips was minimized for improving the photon absorption loss. LED chips were directly attached on the MCPCB by using the COB (Chip On Board) scheme. The LED modules showed significantly enhanced light outputs, compared to the LED modules based on conventional MCPCBs.

• Journal of the Korean Ceramic Society
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• 제54권6호
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• pp.492-498
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• 2017

A thermal barrier coating (TBC) with self-healing property for cracks was proposed to improve reliability during gas turbine operation, including structural design. Effect of healing agent on crack propagation behavior in TBCs with and without buffer layer was investigated through furnace cyclic test (FCT). Molybdenum disilicide ($MoSi_2$) was used as the healing agent; it was encapsulated using a mixture of tetraethyl orthosilicate and sodium methoxide. Buffer layers with composition ratios of 90 : 10 and 80 : 20 wt%, using yttria stabilized zirconia and $MoSi_2$, respectively, were prepared by air plasma spray process. After generating artificial cracks in TBC samples by using Vickers indentation, FCTs were conducted at $1100^{\circ}C$ for a dwell time of 40 min., followed by natural air cooling for 20 min. at room temperature. The cracks were healed in the buffer layer with the healing agent of $MoSi_2$, and it was found that the thermal reliability of TBC can be enhanced by introducing the buffer layer with healing agent in the top coat.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제17권2호
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• pp.150-155
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• 2004

This study attempts to form a TiN barrier layer against Cu diffusion by the easier and more convenient method. In this new approach, Ti was sputter-deposited, and nitrided by heat-treating in the NH$_3$ambient. Sheet resistance of as-deposited Ti was 20 Ω/$\square$, but increased to 195 Ω/$\square$ after the heat-treatment at 30$0^{\circ}C$, and lowered to 120 Ω/$\square$ after the heat-treatment at 50$0^{\circ}C$, and $600^{\circ}C$. AES results for these thin films confirmed that the atomic ratio of Ti and N was close to 1:1 at or above 40$0^{\circ}C$ heat-treatment. However, it was also found that excessive oxygen was contained in the TiN layer. To examine the barrier property against Cu diffusion, 100nm Cu was deposited on the TiN layer and then annealed at 40$0^{\circ}C$ for 40 min.. Cu remained at the surface without diffusing into the Si layer.

• Journal of the Korean institute of surface engineering
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• 제54권6호
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• pp.331-339
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• 2021

Environmental barrier coatings(EBCs) are applied to the SiC/SiC ceramic matrix composites(CMCs) in order to protect CMCs from being corroded with water vapor by combustion gas in gas turbine engines. Ytterbium silicates, such as ytterbium monosilicate and ytterbium disilicate, are ones of the candidate materials for EBCs due to their excellent resistance to water vapor corrosion as well as thermal-expansion match with SiC. In this study, ytterbium silicates are fabricated with 2-step solid-state synthesis targeting ytterbium disilicate. After synthesizing ytterbium monosilicate, the mixtures of ytterbium monosilicate and SiO₂ are heat-treated and densified by using pressureless sintering or hot pressing with a variety of heating conditions. The phase formation, thermal expansion, and oxidation behavior are examined with fabricated specimens. The final densified bodies are found to be composites between ytterbium monosilicate and ytterbium disilicate with different ratios, which results in 4.43 to 6.72×10^-6/K range of coefficients of thermal expansion. The probability of these ytterbium silicates for EBC applications is also discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.303.1-303.1
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• 2016

Polymer-like amorphous carbon films were deposited on polyethylene naphthalate (PEN) substrate by plasma-enhanced chemical vapor deposition (PECVD) and their water vapor transmission rates (WVTR) were tested. propane was used as precursors. To make a polymer-like amorphous carbon film the deposition rate, surface roughness, light transmittance, and WVTR of the films were characterized as a function of the precursor feed ratio and plasma power. The water vapor transmission rates of bare PEN film and single layer PAC on PEN substrate were 6.95 g/m2/day and 0.3 g/m2/day, respectively. The superior property the water vapor permeability of thin layers of PAC was attributed to uniform coverage and good adhesion between PAC film and PEN substrate.

• Journal of the Korean Vacuum Society
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• 제12권S1호
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• pp.40-45
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• 2003

Ru interfacial layer was inserted into Mo-on-Si interface to enhance the extreme ultra-violet (EUV) reflective multilayer properties. The stacking status and optical properties are analyzed using cross-sectional transmission electron microscope (TEM), and reflectometer. About 1.5% of maximum reflectivity can be acquired as predicted in optical simulation, which is thought to be originated from the diffusion inhibition property. Phase defect correctability of the multilayer can be enhanced by the insertion of Ru barrier layer.

• Journal of Environmental Science International
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• 제26권1호
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• pp.1-10
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• 2017

In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/graphene oxide (GO) nanocomposite films containing various content of GO were prepared using solution casting method. The effect of GO content on Young's modulus and dispersion of GO in PHBV matrix was investigated. Also, the thermomechanical properties, oxygen transmission rates and hydrolytic degradation of PHBV/GO nanocomposite films were studied. The addition of GO into PHBV improves the Young's modulus and decreases thermal expansion coefficient. The improvement can be mainly attributed to good dispersion of GO and interfacial interactions between PHBV and GO. Furthermore, PHBV/GO nanocomposite films show good oxygen barrier properties. PHBV/GO nanocomposites show lower hydrolytic degradation rates with increasing content of GO.

• Journal of the Korean Ceramic Society
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• 제55권5호
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• pp.452-460
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• 2018

This study investigate changes in mechanical behaviors such as indentation load-displacement and hardness of thermal barrier coatings (TBCs) using cycling of thermal shock test. Relatively dense and porous TBCs on nickel-based bondcoat/super alloy are prepared using different starting granules, 204C-NS and 204NS commercial powers, and the effect of double layers of 204C-NS on 204NS and 204NS on 204C-NS are investigated. The highest temperature applied during thermal shock test is $1100^{\circ}C$ and the maximum number of cycles is 1,200. The results indicate that bilayered TBC showed a relatively mechanically resistant property during thermal shock cycles and that the mechanical behavior is influenced by the microstructure of TBCs by exposure to high temperature during tests or different starting granules.

• Proceedings of KOSOMES biannual meeting
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.36-36
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• 2017