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        검색결과 147

        61.
        2011.09 구독 인증기관 무료, 개인회원 유료
        WCl6-EtAlCl2 촉매계를 이용하여 비교적 큰 분자량을 갖는 폴리(페닐아세틸렌)을 합성하였다. 중합반응이 잘 진행되었으며 중합수율은 81%였다. 합성한 폴리(페닐아세틸렌) 분자구조를 NMR(1H-,13C-), IR, UV-visible, 원소분석 등으로 분석한 결과 페닐 치환기를 갖는 공액구조 고분자가 합성되었음을 확인할 수 있었다. 아울러 332 nm의 빛으로 여기시킬 경우 PL 최대 peak는 424 nm에서 관찰되었는데, 이는 2.93 eV의 광 에너지에 해당한다. 이 고분자의 순환 전압전류 그림은 도핑과 탈도핑사이에서 비가역적인 전기화학적 거동을 보여주었다. 이 고분자의 전기화학적 과정이 매우 안정하였으며, 스캔속도에 따른 산화전류 밀도 실험으로부터 이 고분자의 산화-환언 과정은 확산-제어과정에 따르는 것으로 분석되었다.
        4,000원
        62.
        2011.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report on the effects of TiO2 doping power on the characteristics of multicomponent TiO2-ITO (TITO) electrodes prepared by a multi-target sputtering system with tilted cathode guns. Both as-deposited and annealed TITO electrodes showed linearly increased sheet resistance and resistivity with increasing TiO2 doping power. However, the TITO electrodes exhibited a fairly high optical transmittance regardless of the TiO2 doping power due to the high transparency of the TiO2. Although the annealed TITO showed much lower sheet resistance and resistivity relative to the as-deposited samples, the electrical properties of the annealed samples exhibited similar dependence on the TiO2 power to the as-deposited samples. In addition, it was found that doping of an anatase TiO2 in the ITO electrode prevented the preferred (222) orientation of the TITO electrodes. Although the TITO electrode showed higher sheet resistance and resistivity than that of the pure ITO electrode, it offers a very smooth surface and usage of a low-cost Ti element. It is thus considered a promising multicomponent transparent conducting electrode for cost-efficient flat panel displays and photovoltatics.
        4,000원
        64.
        2010.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Glass was fabricated using refused coal ore obtained from the Dogye coal mine in Samcheok. We additionally used soda ash and calcium carbonate to make a glass with the chemical composition of soda-lime glass, and we also used white, brown, and green glass cullet to make various kinds of colored glass. Transparent glass was fabricated by melting batch materials including refused coal ore at 1550˚C for 1 hr in an electrical furnace. The light transmittance and color chromaticity were measured by a UV/VIS/NIR spectrometer. Transparent glass with a light transmittance of over 80% was fabricated using normal refused coal ore and white glass cullet. Various kinds of colored glass with a light transmittance of 30-80% were fabricated using refused coal ore and brown or green glass cullet. The light transmittance of the mixed color glass samples, fabricated using normal refused coal ore and brown glass cullet and green glass cullet, indicated 30-47%, a relatively low value, in the condition of a cullet ratio of 20-50%. The characteristics of the color chromaticity of the glass samples were indicated in a chromaticity diagram by x-coordinates, y-coordinates, Y (lightness). The values of x-coordinates and y-coordinates were moved with a regular directional property according to the kind and amount of glass cullet. Therefore, we concluded that refused coal ore can be used for raw materials of color glass products like art glass and glass tile.
        4,200원
        65.
        2010.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Transparent ceramics are used in new technology because of their excellent mechanical properties over glasses. Transparent ceramics are nowadays widely used in armor, laser windows, and in high temperature applications. Silicon nitride ceramics have excellent mechanical properties and if transparent silicon nitride is fabricated, it can be widely used. h-BN has a lubricating property and is ductile. Therefore, adding h-BN to silicon nitride ceramics gives a lubricating property and is also machinable. Translucent silicon nitride was fabricated by hot-press sintering (HPS) and 57% transmittance was observed in the near infrared region. A higher wt. % of h-BN in silicon nitride ceramics does not favor transparency. The optical, mechanical, and tribological properties of BN dispersed polycrystalline Si3N4 ceramics were affected by the density, α:β-phase ratio, and content of h-BN in sintered ceramics. The hot pressed samples were prepared from the mixture of α-Si3N4, AlN, MgO, and h-BN at 1850˚C. The composite contained from 0.25 to 2 wt. % BN powder with sintering aids (9% AlN + 3% MgO). A maximum transmittance of 57% was achieved for the 0.25 wt. % BN doped Si3N4 ceramics. Fracture toughness increased and wear volume and the friction coefficient decreased with an increase in BN content. The properties such as transmittance, density, hardness, and flexural strength decreased with an increase in content of h-BN in silicon nitride ceramics.
        4,000원
        66.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Purpose: The interaction of methylene blue (MB) with Na-saturated clay from Maghnia deposit in aqueous suspension was investigated using visible absorption spectroscopy. Methods: The effect of the optical properties of dyes in aqueous solutions and adsorbed onto Na-saturated clay was assessed in terms of the absorption bands maxima and the removal rate as a function of pH. Results: The adsorption of MB dye onto Na-saturated clay surface leads to the methacromatic effect in the absorption spectrum of the dye. Formation of MB dimers and higher agglomerates depended sensitively on the potential of the layer charge density. MB agglomerates occurred predominantly in the Na-saturated clay with high charge density, even with low charge density. The redistribution of MB molecules over the surface of Na-saturated clay of lower charge density (high acidic medium) leads to a reduction of the dye aggregation, accompanied by a bathochromic shift of the band maximum of MB dye to the longer wavelengths. Conclusion: The methachromatic effect was analyzed by the R=A(MB+)/A(MB+)n parameter, which decreases with the charge density, owing to the increase in the pH solution. To explain the relationship between the layer charge density and the adsorption, so- colled model 2-pKa of surface complexation (SCM) was developed.
        4,000원
        67.
        2010.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, we fabricated a polymer light emitting diode (PLED) and investigated its electrical and optical characteristics in order to examine the effects of the PFO [poly(9,9-dioctylfluorene-2-7-diyl) end capped with N,N-bis(4-methylphenyl)-4-aniline] concentrations in the emission layer (EML). The PFO polymer was dissolved in toluene ranging from 0.2 to 1.2 wt%, and then spin-coated. To verify the influence of the TPBI [2,2',2"-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)]electron transport layer, TPBI small molecules were deposited by thermal evaporation. The current density, luminance, wavelength and current efficiency characteristics of the prepared PLED devices with and without TPBI layer at various PFO concentrations were measured and compared. The luminance and current efficiency of the PLED devices without TPBI layer were increased, from 117 to 553 cd/m2 and from 0.015 to 0.110 cd/A, as the PFO concentration increased from 0.2 to 1.0 wt%. For the PLED devices with TPBI layer, the luminance and current efficiency were 1724 cd/m2 and 0.501 cd/A at 1.0 wt% PFO concentration. The CIE color coordinators of the PLED device with TPBI layer at 1.0 wt% PFO concentration showed a more pure blue color compared with the one without TPBI, and the CIE values varied from (x, y) = (0.21, 0.23) to (x, y) = (0.16, 0.11).
        4,000원
        68.
        2010.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        High Pressure High Temperature (HPHT) treatment can significantly change the color of diamonds. We studied the variation of the optical properties according to the nitrogen arrangement in natural brown diamonds of various types (type IaAB, type IaB, type IaA > B, type IaA< B, IaA = B) after HPHT treatment. The diamonds with different arrangements of nitrogen were annealed at temperatures in the range 1700-1800˚C under a stabilizing pressure of 5 GPa. HPHT treated samples were analyzed using UV-Vis-NIR, FT-IR, and PL spectroscopy. The absorption and luminescence spectra were measured to compare the variations of nitrogen arrangement in the natural brown diamonds before and after HPHT treatment. After HPHT treatment, the brown coloration in all types of diamonds was reduced and a decrease in the peaks related to the A-aggregate of nitrogen was more predominant than the B-aggregate. Furthermore, the peaks related to N3 (415.4 nm), H4 (496.4 nm), and platelet decreased and the peaks related to H3 (503.2 nm) and G-band increased after HPHT treatment. In conclusion, spectroscopic analysis of natural brown diamonds after HPHT treatment showed that a yellow color was produced by absorption in the H3 centers and a green color was generated by interaction between absorptions of the H3 and H2 centers.
        4,200원
        69.
        2009.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Optical characteristics and structural changes depending on CuO content in phosphate glasses that are used in near-infrared (near-IR) filters were investigated. With phosphate glasses that contain 1-9 mol% CuO, changes in optical transmittance, optical absorption, and color coordinate were measured with a UV-VIS spectrophotometer. An XPS (X-ray photoelectron spectroscopy) analysis was performed to determine valence of copper ion that influences optical characteristics in near-IR filter glasses. Structural changes in glasses depending on CuO content were also analyzed by FT-IR (Fourier transform infrared) and Raman spectrophotometers. From the UV-VIS spectrophotometer results, strong absorption peaks at 220 & 900 nm were found and transmittance was decreased. The color coordinates of the glasses were shifted to the green color direction with CuO addition for increasing absorption of long wavelength range spectra, in spite of the amount of Cu2+, which gives a blue color to glasses, and which was increased in XPS results. Also, structural de-polymerization of glasses with CuO addition were found by FT-IR and Raman results.
        3,000원
        70.
        2009.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, we analyzed the effect of silicon oxynitride matrix on the optical properties of Au nanoparticles dispersed on composite film and explored the effectiveness of the silicon in fine tuning the refractive index of the composite film for applications in optical waveguide devices. The atomic fraction of nitrogen in SiOxNy films was controlled by varying the relative flow ratio of nitrogen gas in reactive sputtering and was evaluated optically using an effective medium theory with Bruggeman geometry consisting of a random mixture between SiO2 and Si3N4. The Au nanoparticles were embedded in the SiOxNy matrix by employing the alternating deposition technique and clearly showed an absorption peak due to the excitation of surface plasmon. With increasing nitrogen atomic fraction in the matrix, the surface plasmon resonance wavelength shifted to a longer wavelength (a red-shift) with an enhanced resonance absorption. These characteristics were interpreted using the Maxwell-Garnett effective medium theory. The formation of a guided mode in a slab waveguide consisting of 3 μm thick Au:SiOxNy nanocomposite film was confirmed at the telecommunication wavelength of 1550 nm by prism coupler method and compared with the case of using SiO2 matrix. The use of SiOxNy matrix provides an effective way of controlling the mode confinement while maintaining or even enhancing the surface plasmon resonance properties.
        4,000원
        71.
        2009.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ultraviolet curable coating solution was prepared with poly(ethylene glycol) acrylate oligomer and various mono and multi-functional acrylate monomers. The optical properties of UV cured coating layer on PET film with acrylate coating solution containing metal oxides, such as fumed silica and alumina, were also investigated to reduce light reflection on films. Poly(ethylene glycol) diacrylate which has 575 of average molecular weight was used as oligomer acrylate, and pentaerythritol triacrylate and dipentaerythritolpenta-/hexa acrylate were used as multi-functional acrylate monomers. Also, butyl acrylate was used to improve the adhesion as well as to reduce glass transition temperature to give a better flexability. 1-hydroxy cyclohexyl phenyl ketone was used as photoinitiator. We found out the metal oxides in acrylate coating solution showed a homogeneous dispersion from energy dispersive spectroscopy data. Transmittance and light reflection of coated PET film was measured with UV/vis spectrometer and gloss meter, respectively. When 1.00 g of both metal oxides was added into coating solution, the transmittance and the glossiness were reduced from 90% to 30% and from 190 GU to 35 GU, respectively. However, adding up to 1.00 g of the metal oxide into coating solution did not affect on the hardness of coating layer and adhesion between coated layer and PET film. Conclusively, we can control transmittance and light reflection of coated film by adjusting the amounts of metal oxide in coating solution.
        4,000원
        72.
        2009.12 구독 인증기관 무료, 개인회원 유료
        Heck coupling 반응을 이용해서 poly{2-[2-(2,5-bis-dodecyloxy-4-propenyl-phenyl)-vinyl]- 7-methyl-fluoren-9-one(PFone), poly{2-[2-(2,5-bis-dodecyloxy-4-propenyl-phenyl)-vinyl]-7-methyl-fluoren-9-ylidene}-malonitrile(PF2CN)을 합성하였다. 합성한 중합체의 광학적, 전기화학적 특성을 흡수, 형광분광법 및 cyclic voltammetry(CV)를 통해 확인하였다. PFone과 PF2CN 필름의 흡수 극대치는 410 nm과 410.5 nm에서 나타났다. PFone 및 PF2CN의 최대 발광파장은 각각 633과 635nm로 나타났다. PFone과 PF2CN의 band gap은 각각 2.06eV 과 2.36eV이고 CV를 통해 측정한 LUMO 에너지 준위는 -3.36eV 와 -3.46eV로 나타났다.
        4,000원
        73.
        2009.12 구독 인증기관 무료, 개인회원 유료
        PAQ(poly-2-[2-(2,5-Bis-dodecyloxy-4-vinyl-phenyl)-vinyl]-anthraquinone)과 PAN4CN(poly- 2-{2-[2-(2,5-Bis-dodecyloxy-4-vinyl-phenyl)vinyl]-10-dicyanomethylene-10H-anthracen-9-ylidene}-malononitrile)을 Heck coupling reaction을 이용하여 합성하였다. 합성한 중합체의 전기적, 광학적 특성은 UV-visible spectra, photoluminescence (PL) spectra 및 cyclic voltammetry 측정을 통해 확인하였다. 흡수 스펙트라 측정 결과, thin film에서의 흡수극대치는 PAQ 와 PAN4CN은 334nm에서 나타났고, 용액에서는 PAQ 338nm, PAN4CN은 336nm 나타났다. 발광 극대치의 측정결과 PAQ는 thin film에서 420nm와 용액상에서는 416nm, PAN4CN은 thin film에서 395nm와 용액에서는 550nm로 각각 나타났다. PAQ과 PAN4CN의 band gap은 각각 2.16 eV, 2.04 eV이고 CV를 통해 LUMO 준위는 -3.64eV, -3.52eV로 나타났다.
        4,000원
        74.
        2009.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper presents a new method for the improvement of color temperature without the change of the driving scheme using transparent dielectric layers with various metal oxides (CeO2, Co3O4, CuO, Fe2O3, MnO2, NiO) in plasma display panels (PDP). In this study, we fabricated ZnO-B2O3-SiO2-Al2O3 glasse with various metal oxides and examined the optical properties of these glasses. As the metal oxides were added to the glasses, the visible transmittances of the dielectric layers decreased and the transmittances in special wavelength regions were reduced at different rates. The change of the transmittance in each wavelength range induced the variation of the visible emission spectra and the change of the color temperature in the PDP. The addition of Co3O4 and CuO slightly decreased the intensity of the blue light, but the intensities of the green and the red light were significantly decreased. Therefore, the color temperature can be improved from 6087K to 7378K and 7057K, respectively.
        4,000원
        77.
        2009.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Phase transition in ferroelectric polymer is very interesting behavior and has been widely studiedfor real device applications, such as actuators and sensors. Through the phase transition, there is structuralchange resulting in the change of electrical and optical properties. In this study, we fabricated the Febry-Perotinterferometer with the thin film of ferroelectric P(VDF-TrFE) 50/50mol% copolymer, and thermo-opticalproperties were investigated. The effective thermo-optical coefficient of P(VDF-TrFE) was obtained as 2.3~3.8×10-4/K in the ferroelectric temperature region (45oC~65oC) and 6.0×10-4/K in the phase transition temperatureregion (65oC~85oC), which is a larger than optical silica-fiber and PMMA. The resonance transmission peakof P(VDF-TrFE) with the variation of temperature showed hysteretic variation and the phase transitiontemperature of the polymer in heating condition was higher than in the cooling condition. The elimination ofthe hysteretic phase transition of P(VDF-TrFE) is necessary for practical applications of optical devices.
        3,000원
        78.
        2009.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this report, the structural and optical properties of sol-gel derived MgxZn1-xO thin films upon changes in the composition and annealing temperature were investigated. The Mg2+ content and the annealing temperature were varied in the range of 0≤x≤0.35 and 400˚C≤T≤600˚C, respectively. The films exhibited a hexagonal wurtzite structure of a polycrystalline nature. The optical transmittance exceeded 85% and the optical band gap of the film was tuned as high as 3.84 eV at a value of x = 0.35 (annealed at 400˚C), which was evidently the maximum Mg2+ content for the single-phase polycrystalline MgxZn1-xO thin films prepared in this experiment. The optical band gap and photoluminescence emission were tailored to the higher energy side while maintaining crystallinity without a significant change of the lattice constant.
        4,000원
        79.
        2008.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present optical and near-infrared imaging and long-slit spectroscopy for the blue compact dwarf galaxy (BCD) Mrk 49 in the Virgo Cluster. The surface brightness distribution analysis shows that Mrk 49 consists of an off-centered blue bright compact core of r = 10′′ and a red faint outer exponential envelope. The Hα image and color difference suggest that these two components have different stellar populations: a high surface brightness population of massive young stars and an underlying low surface brightness population of older stars. The redder near-infrared colors of the inner most region suggest that the near-infrared flux of Mrk 49 originates from evolved massive stars associated with the current star-forming activity. The total apparent magnitude is BT = 14.32 mag and the mean effective surface brightness is μeff (B) = 21.56 mag arcsec−2. Long-slit spectroscopy shows that Mrk 49 rotates apparently as a solid body within r = 10′′ in a plane at position angle 55 degrees with an amplitude of about 20 km sec−1. The measured radial velocity of Mrk 49 was derived as 1,535 km sec−1; and the total mass of stars and gases is in the range of 3 to 6 × 109 M⊙. The mass-to-light ratios for the central region of Mrk 49 in I and B band are estimated 1.0 and 0.5, respectively. The upper limit of the dark matter to visible matter ratio seems to be < 5. The oxygen abundance is 12 + log(O/H) = 8.21 ± 0.1 which is about one quarter of the solar value while the relative helium abundance appears to be similar to that of the sun.
        5,100원
        80.
        2008.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Mg-doped and In-Mg co-doped p-type GaN epilayers were grown in a low-pressure metal organic chemical vapor deposition technique. The effect of In doping on the p-GaN layer was studied through photoluminescence (PL), persistent photoconductivity (PPC), and transmission electron microscopy (TEM) at room temperature. For the In-doped p-GaN layer, the PL intensity increases significantly and the peak position shifts to 3.2 eV from 2.95 eV of conventional p-GaN. Additionally, In doping greatly reduces the PPC, which was very strong in conventional p-GaN. A reduction in the dislocation density is also evidenced upon In doping in p-GaN according to TEM images. The improved optical properties of the In-doped p-GaN layer are attributed to the high crystalline quality and to the active participation of incorporated Mg atoms.
        3,000원
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