• Corrosion Science and Technology
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• 제17권3호
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• pp.101-108
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• 2018

AA7010 is an Al-Zn-Mg-Cu alloy containing Zr, developed as an alternate to traditional AA7075 alloy owing to their high strength combined with better fracture toughness. It is necessary to improve the corrosion resistance and surface properties of the alloy by incorporating plasma electrolytic oxidation (PEO) method. AA7010-T7452 aluminum alloy has been processed through the forging route with multi-stage working operations, and was coated with $10{\mu}m$ thick $Al_2O_3$ ceramic aluminina coating using the plasma electrolytic oxidation (PEO) method. The corrosion, stress corrosion cracking (SCC) and nano-mechanical behaviours were examined by means of potentiodynamic polarization, slow strain rate test (SSRT) and nano-indentation tests. The results indicated that the additional thermomechanical treatment during the forging process caused a fully recrystallized microstructure, which lead to the poor environmental cracking resistance of the alloy in 3.5% NaCl solution, despite the overaging treatment. Although the fabricated PEO coating improved general corrosion resistance, the brittle nature of the coating did not provide any improvement in SCC resistance of the alloy. However, the hardness and elastic modulus of the coating were significantly higher than the base alloy.

• 한국결정성장학회지
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• 제23권2호
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• pp.81-85
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• 2013

새로운 표면처리로서 TCF(thermal color fusion) 기술이 적용된 스와로브스키사의 패션 토파즈(passion topaz)의 코팅 층 성분과 적층구조를 파악하기 위해 ED-XRF와 TOF-SIMS 분석을 실시하였다. 더불어 감별특징 관찰을 위한 확대검사와 내구성 평가를 미스틱 토파즈(mystic topaz)와 비교 분석하였다. 그 결과, 패션 토파즈에서도 미스틱 토파즈에서 보이는 유사한 특징들이 확대검사를 통해 관찰되었고, TOF-SIMS에 의한 depth profile 분석 결과에서 토파즈 표면으로의 확산코팅과 다층구조 코팅이 되어있음을 알 수 있었다. 또한 패션 토파즈는 금속 원소간의 화학반응에 의한 코팅처리로 미스틱 토파즈 보다 화학약품에 대한 안정적인 특성과 높은 모스경도를 보였다.

• 한국세라믹학회지
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• 제53권6호
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• pp.689-699
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• 2016

The effects of composition, structure design, and coating thickness of thermal barrier coating (TBC) on thermal barrier performance were investigated by measuring the temperature differences of TBC samples. TBCs with the thin and thick top coats were used for these studies, including TBCs with rare-earth (Gd, Yb, and La) compositions. The thermal barrier performance was enhanced with increasing the thickness of top coat even for thin TBCs, indicating that the thermal barrier performance was commensurate to the thickness of top coat. On the other hand, the bi-layered TBC, which was prepared with Yb-Gd-YSZ feedstock powder, with the buffer layer of high purity 8YSZ showed a better thermal barrier performance than that of regular purity 8YSZ. The interfaces in the bi-layered TBCs had a decisive effect on the thermal barrier performance, showing the performance enhanced with increasing numbers of interfaces. However, a new structural design and an additional process should be considered to reduce stress concentrations and to ensure interface stability, respectively, for improving thermal durability in the multi-layered TBCs.

• 전자공학회논문지
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• 제50권7호
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• pp.102-108
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• 2013

용액 공정 기반으로 유기 전자소자를 제작할 시, 회전 도포 방법을 이용하는데 이 방법의 단점 중의 하나는 후속 회전 도포할 때 용액 속의 용매에 의해 이미 제작된 유기 박막을 물리적 또는 화학적인 손상을 입힐 수 있다는 것이다. 이러한 문제들로 인해 후속적인 박막 제조에 사용될 수 있는 용매의 종류는 매우 제한적일 수 밖에 없다. 본 논문에서는 기존에 알려진 용매들의 적절한 조합으로 인해 다층 박막 제작이 가능함을 보이고, 이를 이용하여 용액 공정 기반 유기 트랜지스터를 제작하여 성능의 향상을 보일 것이다. 트랜지스터의 구조는 하부 게이트 하부 접촉 (bottom gate, bottom contact) 구조로 제작되었고 게이트 절연체는 강유전체 고분자로 제작되었는데 한 번의 회전 도포 방법과 두 번의 회전 도포 방법으로 동일 두께를 형성하여 두 트랜지스터를 제작, 드레인 전압에 따른 소스-드레인 전류를 비교하였다. 그 결과 소스-게이트 누설 전류 감소 효과가 있었고, ON 상태에서의 소스-드레인 전류의 상승효과도 관찰되었다. 전류-전압 그래프로부터 계산된 이동도는 약 2.7배 증가되었다. 그러므로 용액 공정 기반 전계효과 트랜지스터를 제작할 시, 게이트 절연체를 다층 구조로 제작하면 성능 향상에 이점이 많다는 것을 알 수 있었다.

• 한국세라믹학회지
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• 제46권5호
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• pp.534-539
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• 2009

Reaction Bonded Silicon Carbide(RBSC) has been used for engineering ceramics due to low-temperature fabrication and near-net shape products with excellent structural properties such as thermal shock resistance, corrosion resistance and mechanical strength. Recently, attempts have been made to develop hot gas filter with gradient pore structure by RBSC to overcome weakness of commercial clay-bonded SiC filter such as low fracture toughness and low reliability. In this study a fabrication process of porous RBSC with multi-layer pore structure with gradient pore size was developed. The support layer of the RBSC with multi-layer pore structure was fabricated by conventional Si infiltration process. The intermediate and filter layers consisted of phenolic resin and fine SiC powder were prepared by dip-coating of the support RBSC in slurry of SiC and phenol resin. The temperature of $1550^{\circ}C$ to make Si left in RBSC support layer infiltrate into dip-coated layer to produce SiC by reacting with pyro-carbon from phenol resin.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.985-987
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• 2004

A plastic substrate for flexible display is developed. The gas barrier property in the substrate is improved through depositing metal and metal oxide multi layer on plastic film by PVD process. The metal/metal-oxide multiplayer on plastic film shows excellent gas barrier property and optical property.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 광학 및 양자전자학 워크샵
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• pp.123-132
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• 1990

The method of characteristic matrix used in the calculation of multi-layered optical coating is applied to the analysis of DFB waveguide with arbitrary structure of grating by plecewise approximation where the DFB structure is devided into many sections in which the gain and period, amplitude and phase of DFB structure are assuced to be constant in each section. The DFB structure with two section is analyzed using this method of C-matrix. The possible applications for photonic devices using DFB waveguides are proposed.

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.187-188
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• 2007

Four kinds of mirror substrates with same surface roughness were fabricated. On those substrates, a dielectric multi-layer coating with high reflectivity was deposited by ion beam sputtering technique. Most of the fused silica mirrors showed lower scattering than the ZERODUR mirrors one, which deposited on substrates similar in surface roughness. The ZERODUR mirrors scattering strongly depend on the micro-structure of $Ta_2O_5/SiO_2$ thin films wear deposited on ZERODUR substrates.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2005년도 춘계학술발표대회 및 제8회 신소재 심포지엄 논문개요집
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• pp.111-111
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• 2005

• 한국인쇄학회지
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• 제11권1호
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• pp.85-101
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• 1993

Poly(vinyl cinnamate) had excellent resolution and no dark reaction and high etch resistent. But is was developed in polar solvent. A aqueous-photopolymer was synthesised for improvment of developability. Poly(vinyl cinnamoyl acetate)(PVCiA) and aqueous-PVCiA(PVCiA-s) was prepared and was characterized with H-NMR. The characteristic of sensitivity and developablity of coating was investigated by Grayscale method.