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        검색결과 119

        41.
        2014.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Solution-based Sb-doped SnO2 (ATO) transparent conductive oxides using a low-temperature process werefabricated by an electrospray technique followed by spin coating. We demonstrated their structural, chemical, morphological,electrical, and optical properties by means of X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanningelectron microscopy, atomic force microscopy, Hall effect measurement system, and UV-Vis spectrophotometry. In order toinvestigate optimum electrical and optical properties at low-temperature annealing, we systemically coated two layer, four layer,and six layers of ATO sol-solution using spin-coating on the electrosprayed ATO thin films. The resistivity and opticaltransmittance of the ATO thin films decreased as the thickness of ATO sol-layer increased. Then, the ATO thin films with twosol-layers exhibited superb figure of merit compared to the other samples. The performance improvement in a low temperatureprocess (300oC) can be explained by the effect of enhanced carrier concentration due to the improved densification of the ATOthin films causing the optimum sol-layer coating. Therefore, the solution-based ATO thin films prepared at 300oC exhibitedthe superb electrical (~7.25×10−3Ω·cm) and optical transmittance (~83.1%) performances.
        4,000원
        42.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Clear cell adenocarcinoma (CCA) is a rare malignant neoplasm of salivary gland that represents only 1% of all salivary gland tumors. CCA is histopathologically characterized by monotonous, glycogen-rich, round to ovoid clear cells intermixed with hyalinized stroma. However, other salivary gland tumors such as mucoepidermoid carcinoma, acinic cell adenocarcinoma, oncocytoma, epithelial-myoepithelial carcinoma, and myoepithelial carcinoma should be ruled out to diagnosis CCA. We herein report a case of CCA involving the soft palate in a 56-year-old female. It is essential to consider CCA in the differential diagnoses of clear cell tumors.
        4,000원
        43.
        2013.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigated the detection properties of nitrogen monoxide (NO) gas using transparent p-type CuAlO2 thin film gas sensors. The CuAlO2 film was fabricated on an indium tin oxide (ITO)/glass substrate by pulsed laser deposition (PLD), and then the transparent p-type CuAlO2 active layer was formed by annealing. Structural and optical characterizations revealed that the transparent p-type CuAlO2 layer with a thickness of around 200 nm had a non-crystalline structure, showing a quite flat surface and a high transparency above 65 % in the range of visible light. From the NO gas sensing measurements, it was found that the transparent p-type CuAlO2 thin film gas sensors exhibited the maximum sensitivity to NO gas in dry air at an operating temperature of 180˚C. We also found that these CuAlO2 thin film gas sensors showed reversible and reliable electrical resistance-response to NO gas in the operating temperature range. These results indicate that the transparent p-type semiconductor CuAlO2 thin films are very promising for application as sensing materials for gas sensors, in particular, various types of transparent p-n junction gas sensors. Also, these transparent p-type semiconductor CuAlO2 thin films could be combined with an n-type oxide semiconductor to fabricate p-n heterojunction oxide semiconductor gas sensors.
        4,000원
        44.
        2012.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        For the purpose of improving the durability problem, translucent opal glass was fabricated as a substitute for the polycarbonate diffuser of LED lighting. Calcium phosphate was used as an opacifier of opal glass and melted in an electric furnace. The opaque effect was identified according to the change of the cooling procedure. As results, translucent opal glass was obtained by the melting of a batch with a composition of 3.8% calcium phosphate at 1550˚C for 2 hrs and then the cooling of the material in the furnace. For the cooling condition of the glass sample, HTCG (High Temperature Cooled Glass) was found to have better optical properties than LTAG (Low Temperature Annealed Glass). It had excellent optical properties for a diffuser of LED lighting, with no dazzling from direct light due to its high haze value of over 99% and low parallel transmittance value of under 1%. For the thermal properties, it had an expressed thermal expansion coefficient of 5.7×10-6/˚C and a softening point of 876˚C; it also had good thermal properties such as good thermal shock resistance and was easy to apply to the general manufacturing process in the forming of glass tubes and bulbs. Therefore, it is concluded that this translucent opal glass can be used as a glass diffuser material for LED lighting with high heat resistance and high durability; this material is suitable as a substitute for polycarbonate diffusers.
        4,000원
        45.
        2012.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Metal nanowires can be coated on various substrates to create transparent conducting films that can potentially replace the dominant transparent conductor, indium tin oxide, in displays, solar cells, organic light-emitting diodes, and electrochromic windows. One issue with these metal nanowire based transparent conductive films is that the resistance between the nanowires is still high because of their low aspect ratio. Here, we demonstrate high-performance transparent conductive films with silver nanofiber networks synthesized by a low-cost and scalable electrospinning process followed by two-step sequential thermal treatments. First, the PVP/AgNO3 precursor nanofibers, which have an average diameter of 208 nm and are several thousands of micrometers in length, were synthesized by the electrospinning process. The thermal behavior and the phase and morphology evolution in the thermal treatment processes were systematically investigated to determine the thermal treatment atmosphere and temperature. PVP/AgNO3 nanofibers were transformed stepwise into PVP/Ag and Ag nanofibers by two-step sequential thermal treatments (i.e., 150˚C in H2 for 0.5 h and 300˚C in Ar for 3 h); however, the fibrous shape was perfectly maintained. The silver nanofibers have ultrahigh aspect ratios of up to 10000 and a small average diameter of 142 nm; they also have fused crossing points with ultra-low junction resistances, which result in high transmittance at low sheet resistance.
        4,000원
        46.
        2012.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 실험에서는 투명비누를 만드는데 사용되는 폴리올의 최적 농도를 실험계획법을 이용하여 결정하였다. 짧은 사슬을 보유한 디프로필렌글리콜과 1,3 부틸렌글리콜은 비누의 투명도를 증가시켰으나 폴리에틸렌글리콜 400, 글리세린과 디글리세린은 비누를 불투명하게 하였다. 프로필렌글리콜, 디글리세린, 디프로필렌글리콜 및 폴리에틸렌글리콜의 농도를 증가시키면 비누의 경도는 증가하였다. 경도, 투명도, 물의 흡수성 및 마찰 용해도는 디프로필렌글리콜, 폴리에틸렌글리콜, 설탕과 트리에탄올아민의 농도를 조절하여 최적화할 수 있었다.
        4,000원
        47.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Transparent liquid crystal gels with high oil content by fatty acid soap were investigated. The solubilization efficiency of the mineral oil was dependent on the process. The process of dropping water part into the solution of oil and surfactant was more efficient than the process of dropping water part into the surfactant solution and after that dropping oil. The fatty acid soap could not solubilize the high oil content, but under the certain range, addition of CDE (Coconut Diethanolamide), Arlacel 165 (Glyceryl Stearate/PEG-100 Stearate) and cetostearyl alcohol helped solubilize the high content oil. Also, the glycerin and water content had influence on the solubilization. Especially, higher oil content gel showed elastic feature.
        4,000원
        48.
        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
        49.
        2011.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have investigated the structural and electrical properties of Ga-doped ZnO (GZO) thin films deposited by anRF magnetron sputtering at various RF powers from 50 to 90W. All the GZO thin films are grown as a hexagonal wurtzitephase with highly c-axis preferred parameters. The structural and electrical properties are strongly related to the RF power. Thegrain size increases as the RF power increases since the columnar growth of GZO thin film is enhanced at an elevated RFpower. This result means that the crystallinity of GZO is improved as the RF power increases. The resistivity of GZO rapidlydecreases as the RF power increases up to 70W and saturates to 90W. In contrast, the electron concentration of GZO increasesas the RF power increases up to 70W and saturates to 90W. GZO thin film shows the lowest resistivity of 2.2×10−4Ωcmand the highest electron concentration of 1.7×1021cm−3 at 90W. The mobility of GZO increases as the RF power increasessince the grain boundary scattering decreases due to the reduced density of the grain boundary at a high RF power. Thetransmittance of GZO thin films in the visible range is above 90%. GZO is a feasible transparent electrode for application asa transparent electrode for thin film solar cells.
        4,000원
        50.
        2011.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have investigated the structural and optical properties of Ga-doped ZnO (GZO) thin films deposited by RFmagnetron sputtering at various deposition temperatures from 100 to 500oC. All the GZO thin films are grown as a hexagonalwurtzite phase with highly c-axis preferred parameter. The structural and electrical properties are strongly related to depositiontemperature. The grain size increases with the increasing deposition temperature up to 400oC and then decreases at 500oC. Thedependence of grain size on the deposition temperature results from the variation of thermal activation energy. The resistivityof GZO thin film decreases with the increasing deposition temperature up to 300oC and then decreases up to 500oC. GZO thinfilm shows the lowest resistivity of 4.3×10−4Ωcm and highest electron concentration of 1.0×1021cm−3 at 300oC. The mobilityof GZO thin films increases with the increasing deposition temperature up to 400oC and then decreases at 500oC. GZO thinfilm shows the highest resistivity of 14.1cm2/Vs. The transmittance of GZO thin films in the visible range is above 87% atall the deposition temperatures. GZO is a feasible transparent electrode for the application to the transparent electrode of thinfilm solar cells.
        4,000원
        51.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Most TCOs such as ITO, AZO(Al-doped ZnO), FTO(F-doped SnO2) etc., which have been widely used in LCD,touch panel, solar cell, and organic LEDs etc. as transparent electrode material reveal n-type conductivity. But in order to realizetransparent circuit, transparent p-n junction, and introduction of transparent p-type materials are prerequisite. Additionalprerequisite condition is optical transparency in visible spectral region. Oxide based materials usually have a wide optical band-gap more than ~3.0eV. In this study, single-phase transparent semiconductor of SrCu2O2, which shows p-type conductivity, havebeen synthesized by 2-step solid state reaction at 950oC under N2 atmosphere, and single-phase SrCu2O2 thin films of p-typeTCOs have been deposited by RF magnetron sputtering on alkali-free glass substrate from single-phase target at 500oC, 1%H2/(Ar+H2) atmosphere. 3% H2/(Ar+H2) resulted in formation of second phases. Hall measurements confirmed the p-typenature of the fabricated SrCu2O2 thin films. The electrical conductivity, mobility of carrier and carrier density 5.27×10−2S/cm,2.2cm2/Vs, 1.53×1017/cm3 a room temperature, respectively. Transmittance and optical band-gap of the SrCu2O2 thin filmsrevealed 62% at 550nm and 3.28eV. The electrical and optical properties of the obtained SrCu2O2 thin films deposited by RFmagnetron sputtering were compared with those deposited by PLD and e-beam.
        4,000원
        52.
        2010.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Transparent conducting oxide (TCO) films are widely used for optoelectronic applications. Among TCO materials,zinc oxide (ZnO) has been studied extensively for its high optical transmission and electrical conduction. In this study, the effectsof O2 plasma pretreatment on the properties of Ga-doped ZnO films (GZO) on polyethylene naphthalate (PEN) substrate werestudied. The O2 plasma pretreatment process was used instead of conventional oxide buffer layers. The O2 plasma treatmentprocess has several merits compared with the oxide buffer layer treatment, especially on a mass production scale. In this process,an additional sputtering system for oxide composition is not needed and the plasma treatment process is easily adopted as anin-line process. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesionbetween the PEN substrate and the GZO film, the O2 plasma pre-treatment process was used prior to GZO sputtering. As theRF power and the treatment time increased, the contact angle decreased and the RMS surface roughness increased significantly.It is believed that the surface energy and adhesive force of the polymer surfaces increased with the O2 plasma treatment andthat the crystallinity and grain size of the GZO films increased. When the RF power was 100W and the treatment time was120 sec in the O2 plasma pretreatment process, the resistivity of the GZO films on the PEN substrate was 1.05×10-3Ω-cm,which is an appropriate range for most optoelectronic applications.
        4,000원
        53.
        2010.03 구독 인증기관 무료, 개인회원 유료
        Existing non-destructive test for evaluation of concrete compressive strength may show deviation in results analysis due to deterioration of precision by strength calibration and dry or humid condition by age, so there needs be testing method to determine long term structural internal force by collecting specimen with no damage of structure and measuring compressive strength through destruction test. This research applied to mock-up member the compressive strength evaluation method using joint separation mold that can plan and produce specimen cured in the same composition environment as concrete structure by attaching arbitrary(joint separation) to the form before concrete piling, and as a result, the management specimen was contrary to the hydration temperature of the member or was affected by external atmospheric temperature, however the joint separation specimen connected to structure and managed in the same environment showed a temperature curve similar to the member and decrease in temperature difference. Additionally, from initial age, with the compressive strength of joint separation specimen most similar to core strength,stable compressive strength can be evaluated up to design criteria strength 100MPa, so the method is proposed as an evaluation technique that can confirm highly reliable concrete quality.
        4,000원
        54.
        2010.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Transparent conductive films of single wall carbon nanotube (SWCNT) were prepared by spray coating method. The effect of acid treatment on the SWCNT films was investigated. The field emission scanning electron microscope (FESEM) shows that acid treatment can remove dispersing agent. The electrical and optical properties of acid-treated films were enhanced compared with those of as deposited SWCNT films. Nitric acid (HNO3), sulfuric acid (H2SO4), nitric acid:sulfuric acid (3:1) were used for post treatment. Although all solutions reduced sheet resistance of CNT films, nitric acid can improve electrical characteristics efficiently. During acid treatment, transmittance was increased continuously with time. But the sheet resistance was decreased for the first 20 minutes and then increased again. Post-treated SWCNT films were transparent (85%) in the visible range with sheet resistance of about 162Ω/sq. In this paper we discuss simple fabrication, which is suitable for different types of large-scale substrates and simple processes to improve properties of SWCNT films.
        3,000원
        55.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to comparatively identify characteristics of turbid water influence in Imha Reservoir, Soyang Reservoir, and Daecheong Reservoir in Korea. We used 3 years dataset from 2002 to 2004 and analyzed seasonal water quality characteristics, particular parameters in association with turbidity, and light transparency to figure out the trends. All parameters to be used in the study were total phosphate (TP), total nitrogen (TN), chlorophyll-a (Chl), suspended solids (SS), Secchi depth (SD), conductivity, and vertical light extinction coefficienct (Kd), euphotic zone (Zeu), and critical depth (Zp). All parameters depend on season and watershed. Suspended solids from Soyang Reservoir were usually caused by TP, mainly related to living wastes and agricultures in upper stream. Daecheong Reservoir was influenced by organic matters related to large phytoplankton biomass in summer and inorganic suspended solids by nutrients in the winter. However, in case of Imha Reservoir, turbid water, consisted in silt and clay through heavy precipitation remained in the waterbody to decrease water transparency along with TP and caused the light limitation in winter. Overall results suggest that it was necessary to establish various management programs because the reasons occurring turbidity were varied according to the reservoir circumstances.
        4,200원
        58.
        2009.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Changes in the surface morphology and light scattering of textured Al doped ZnO thin films on glasssubstrates prepared by rf magnetron sputtering were investigated. As-deposited ZnO:Al films show a hightransmittance of above 80% in the visible range and a low electrical resistivity of 4.5×10-4Ω·cm. The surfacemorphology of textured ZnO:Al films are closely dependent on the deposition parameters of heater temperature,working pressure, and etching time in the etching process. The optimized surface morphology with a cratershape is obtained at a heater temperature of 350oC, working pressure of 0.5 mtorr, and etching time of 45seconds. The optical properties of light transmittance, haze, and angular distribution function (ADF) aresignificantly affected by the resulting surface morphologies of textured films. The film surfaces, havinguniformly size-distributed craters, represent good light scattering properties of high haze and ADF values.Compared with commercial Asahi U (SnO2:F) substrates, the suitability of textured ZnO:Al films as frontelectrode material for amorphous silicon thin film solar cells is also estimated with respect to electrical andoptical properties.
        4,000원
        59.
        2009.03 구독 인증기관 무료, 개인회원 유료
        An evaluation of the concrete strength has very important meaning in the maintenance and the structural safety. The reliability of ferroconcrete building is weakening and enlarging the life is strongly demanded due to the early deterioration of concrete. Like this social demand, concrete strength presumption is being indirectly executed using the result in parallel with the concrete pouring by material age. This data is usually different as concrete poured practically and the way of hardening and curing. Although existing concrete strength presumption formula is proposed, the material used and the concrete strength is different. And as a matter of remicon, the concrete strength varies according to the site and the way of curing. So the objective of this research is strength evaluation of the structural body concrete according to the concrete pouring and curing temperature change seasonally after using the system which evaluates the structural body concrete strength which is applied the transparent junction-separation mold that is presented. Also there is an objective to present the fundamental data for the constructional quality technique proposal of the structural body concrete developed in relation to field specimen and the strength evaluation method by non-breaking.
        4,000원
        60.
        2008.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study investigates Bi2O3-B2O3-BaO-ZnO glass with variations of the Co3O4 content (0.25,0.5,1,and 2wt%) and the interaction between transparent dielectric and Ag electrodes heat-treated at 500-560oC for30min. The glass transition temperature, softening temperature and thermal expansion coefficient were432oC, 460oC and 81.4×10-7/oC, respectively. The transmittance of 0.25wt% Co3O4 to which dielectric wasadded was highest and was decreased due to coloration with the addition of more than 0.25wt%. However,without Co3O4, the transmittance of the transparent layer was decreased due to the formation of Ba5Bi3;however, the occurrence of the crystal phase decreased as a result of the addition of Co3O4. The amount ofCo2+ ions increased as the Co3O4 increased. With a maximum of Co3+ ions, the highest transmittance wasobserved.
        4,000원
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