• 한국표면공학회지
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• 제38권2호
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• pp.83-87
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• 2005

We enhanced the color of blue sapphires and rubies successfully by using a oxygen-propane torch flame annealing, which had not been employed so far. We confirmed that about 1 mm-thick de-coloring of the corundum samples were available with 60 minutes flame annealing through eye evaluation, color coordination characterization, and methylene iodide immersion observation. We also suggest that the color centers such as $[Fe_{Al}^{\cdot}]$ may transform into transparent $[Fe_{Al}^{x}],\;[Cr_{A1}^{x}]$ sites with $[V_o^']$ generation at the elevated temperature in oxygen-rich atmosphere by diffusion mechanism. Our results implied that the longer diffusion time and the higher oxygen partial pressure might lead to the better de-coloring enhancement in corundum gem stones.

• Corrosion Science and Technology
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• 제5권1호
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• pp.15-22
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• 2006

The introduction of two-grid inside a conventional process system produces a reactive coating deposition and increases metal ion ratio in the plasma, resulting in denser and smoother films. The corrosion behaviors of TiN coatings were investigated by electrochemical methods, such as potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in deaerated 3.5% NaCl solution. Electrochemical tests were used to evaluate the effect of microstructure on the corrosion behavior of TiN coatings exposed to a corrosive environment. The crystal structure of the coatings was examined by X-ray diffractometry (XRD) and the microstructure of the coatings was investigated by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). In the potentiodynamic polarization test and EIS measurement, the corrosion current density of TiN deposited by two grid-attached magnetron sputtering was lower than TiN deposited by conventional magnetron type and also presented higher Rct values during 240 h immersion time. It is attributed to the formation of a dense microstructure, which promotes the compactness of coatings and yields lower porosity.

• Corrosion Science and Technology
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• 제15권2호
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• pp.92-107
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• 2016

Graphene was coated on austenitic and martensitic stainless steels to simulate the metallic bipolar plate of proton exchange membrane fuel cell (PEMFC). Graphene oxide (GO) was synthesized and was reduced to reduced graphene oxide (rGO) via a hydrazine process. rGO was confirmed by FE-SEM, Raman spectroscopy and XPS. Interfacial contact resistance (ICR) between the bipolar plate and the gas diffusion layer (GDL) was measured to confirm the electrical conductivity. Both ICR and corrosion current density decreased on graphene coated stainless steels. Corrosion resistance was also improved with immersion time in cathodic environments and satisfied the criteria of the Department of Energy (DOE), USA. The total concentrations of metal ions dissolved from graphene coated stainless steels were reduced. Furthermore hydrophobicity was improved by increasing the contact angle.

• 박물관보존과학
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• 제6권
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• pp.67-71
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• 2005

대구 시지동 생활유적 우물 내부에서 출토된 목제 두레박을 보존처리 하였다. 두레박은 오랜 매장 기간으로 인해 육안 관찰만으로도 부후가 상당히 진행된 것을 알 수 있었다. 취약한 상태의 유물 보존처리를 위하여 세틸알콜을 사용하였으며, 알콜의 농도를 점차 상승시키면서 목재내 수분을 알콜로 치환한 후, 세틸알콜 농도를 20%, 40%, 60%, 80%로 20%씩 농도를 상승시키고 각 농도단계에서 2주간씩 함침처리 하였다. 함침 완료 후 표면의 잔류 세틸알콜을 제거하고 자연건조를 실시하였다.

• Journal of Welding and Joining
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• 제20권5호
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• pp.106-112
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• 2002

In the present study, the wettability and interfacial tension between (bare Cu, electroless Ni/cu, immersion Au/Ni/Cu) substrates and indium solder were investigated as a function of soldering temperature, types of flux. The wettability of In solder increased with soldering temperature and solid content of flux. The wettability of In solder was affected by the substrate metal finish used, i.e., nickel, gold and copper. On the bare Cu substrate, In solder wet better than any of the substrate metal finishes tested. Intermetallic compound formation between liquid solder and substrate reduced the interfacial energy and improved wettability. For the identification of intermetallic compounds, X-Ray Diffraction(LRD) were employed. Experimental results showed that the intermetallic compounds, such as Cu11In9 and In27Ni10 are observed f3r different substrates respectively. The wetting kinetics is investigated by measuring wetting time with the wetting balance technique. The activation energy of wetting calculated for the In solder/cu substrate and In solder/electroless Au/Ni/Cu substrate are 36.13 and 27.36 kJ/mol, respectively.

• 디지털산업정보학회논문지
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• 제10권1호
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• pp.147-155
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• 2014

The rapid increase in the penetration rate and diverse utility of smart devices opens an opportunity for a development in creating a user-oriented ubiquitous system. And it allows audiences to deploy the exhibition-helping contents regardless of the restriction of place and time with using the smart devices of audience themselves. Also it needs to build a mobile web-based portal system for the related services. To do this, Firstly, it needs the corresponding strategies on a smartphone-based environment such as technical competence, systematic preparation of exhibition with compatible mobile contents, and a compatible channel for interactivity. Secondly, it needs the differentiation of exhibition guide with the existing system: an adoption of augmented reality, panoramic technology and simulation effect aiming for an improvement in a sense of immersion and reality for audience, and building up additional contents with a diversity of formats of image, sound, and video for customer satisfaction.

• 한국표면공학회지
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• 제43권4호
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• pp.187-193
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• 2010

The colored films formed on 304 stainless steel plates by immersion treatment and electrochemical one in a solution containing sulphuric acids and chromic acids were studied by SEM, AES, and spectrophotometer. The thicknesses of the films by 20 minutes treatment were about 200 nm and it became thinner as the treatment times were increased. The surface texture showed a tortuous network of interlinking pathways. The color of the 304 steel surface changed from metallic white to gray, black, red, yellow-green, and green-blue, gradually, by the treatment time was increased. The reflectivity measured by UV-VIS-NIR spectrophotometer was reduced from max. 38% of basis metal to min. 3.5% of colored surface.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.217-220
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• 2005

As this study is to test effects of sulfate attack on deterioration of concrete using in crushed aggregates. Besides tests have been carried out with concrete by river sand and crushed sand by fine sand, concrete mixes various proportions of slica fume and fly ash(up to 15$\%$ by weight fo cement) were prepared and immersed in pure water, sodium sulfate solution for 28 and 60days. Test on the change in the weight and compressive strength of concrete according to the duration of immersion time and the content of slica fume and fly ash was performed.

• 전자통신동향분석
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• 제33권2호
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• pp.48-55
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• 2018

Immersive media, which maximizes the viewer's sense of presence and immersion, has been developed in the form of 3D stereoscopic media and UHD media. Going one step further, VR media, which can provide immersive experiences within an artificially created environment, have recently been considered a type of next-generation media. Within this trend, numerous IT and broadcasting companies around the world are actively investing their time and resources to boost the emerging VR industry. In this paper, we introduce the representative VR media acquisition and broadcasting service technologies that are leading the current VR industry.

• 산업기술연구
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• 제31권A호
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• pp.59-62
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• 2011

The demineralizing effect of chelating agents(Maleic acid solution, EDTA salts solutions; disodium-, trisodium- and tetrasodium-EDTA) on hydroxyapatite(HA) for the root canal dentin treatment was investigated. Dissolution of Ca from HA was increased with increasing immersion time in chelating solutions. Among the EDTA salts solutions, tetrasodium-EDTA was least effective in dissolving Ca out from HA, and trisodium-EDTA was the most effective. Trisodium-EDTA solutionmight be more effective in removing the smear layer compared to tetrasodium-EDTA solution.