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91.
Myoungho Pyo Eun Gyoung Bae Younkyung Cho Youn Su Jung KyuKwan Zong 《Synthetic Metals》2010,160(19-20):2224-2227
The composites of multi-walled carbon nanotubes (MWNT) wrapped with low bandgap conjugated polymer and poly(methyl methacrylate) (PMMA) were prepared for transparent conductive films. NIR-absorbing poly(ethyl thieno[3,4-b]thiophene-2-carboxylate) (PTTEt) with Eg of 1.0 eV was used in this study. Upon hybridization with MWNT, PTTEt in an insulating state became partially conductive due to electron transfer from PTTEt to MWNT, meaning that PTTEt can function as conductive glue interconnecting MWNT in a PMMA matrix. The electrical conduction of the composites (PTTEt-MWNT/PMMA), consisting of PTTEt-wrapped MWNT (PTTEt-MWNT/PMMA) and PMMA, showed the percolation at 0.10 wt% MWNT loading, which was ca. 0.18 wt% lower than the composites of MWNT and PMMA (MWNT/PMMA). The maximum conductivity of PTTEt-MWNT/PMMA, on the other hand, was one order of magnitude lower than that of MWNT/PMMA, suggesting that PTTEt incorporation onto MWNT for transparent conductive films is effective within a specific range of MWNT loadings (i.e., between percolation thresholds of MWNT/PMMA and PTTEt–MWNT/PMMA). The comparison of transmittance of PTTEt–MWNT/PMMA (0.18 wt% MWNT) with MWNT/PMMA (0.32 wt% MWNT), possessing the same conductivities (3 × 10?3 S cm?1), showed ca. 10% enhanced transmittance at 550 nm. These results imply that hybridization of low bandgap conjugated polymers with carbon nanotubes can be utilized for the reduction of percolation threshold and the increase of optical transparency without sacrificing conductivities at low MWNT loadings. 相似文献
92.
Sang-Yong Eom Dae-Woong Pyo Seung-Kon Ryu 《Korean Journal of Chemical Engineering》2010,27(2):677-682
Different shaped carbon fibers (R-, I-, C-, Y-, and X-type) were prepared from melt-spinning of reformed naphtha cracking
bottom oil precursors through various shaped spinnerets. These different shaped CFs (carbon fibers) and PVC (polyvinyl chloride)
resin were compounded, and then CF/PVC composites were prepared. Precursor pitch, carbon fibers, and composites were characterized
and their properties were compared. Mechanical properties of carbon fibers and composites were characterized relating to external
surface area and ratio of perimeter to cross-sectional area of carbon fibers. The tensile strength of tetralobal fibers (X-type)
showed five times higher than that of round-shaped fibers (R-type) due to extended external surface area. Their tensile strength
of CF/PVC composite increased as ratio of perimeter to cross-sectional area of carbon fibers. The magnitude of the ratio was
in order to X-, C-, I-, Y-, and R-type. 相似文献
93.
Hui Lu Linlin Zhu Jong Pyo Kim Sou Hwan Son Jung Hoon Park 《Journal of Materials Science》2012,47(5):2169-2174
The novel Fe/Nb/Ti co-substituted Sr(Co0.8Fe0.1Nb0.1)1−x
Ti
x
O3−δ (x = 0.00, 0.20, 0.40) oxides have been synthesized by the solid-state reaction method. These co-substituted strontium cobaltates
possess a cubic perovskite-type structure at room temperature. Structural stability and sintering properties of the samples
x = 0.00, 0.20, 0.40 were investigated by X-ray diffraction (XRD), thermogravimetry (TG), and scanning electron microscopy.
The combined TG and XRD results demonstrate that the structural and chemical stability of the Fe/Nb/Ti co-substituted Sr(Co0.8Fe0.1Nb0.1)1−x
Ti
x
O3−δ (x = 0.20, 0.40) oxides is improved greatly compared with the sample x = 0.00 and the Ba0.5Sr0.5Co0.8Fe0.2O3−δ
oxide. 相似文献
94.
A multiband meandered monopole antenna is proposed for digital video broadcasting handheld (DVB‐H), global positioning system, personal communications service, wireless broadband (Wibro), and wireless local area network (WLAN) applications. The proposed antenna consists of a meandered line, a shorted length strip line, and a conductor strip between a meandered line and a microstrip feed line. By tuning a short strip and a conductor, a multiband impedance matching is achieved. The proposed antenna has an omnidirectional radiation and yields an antenna gain of greater than ?3 dBi in the DVB‐H band and 4.5 dBi in the Wibro and WLAN bands. Details of the proposed antenna design and experimental results are presented. 相似文献
95.
Hyung Woo Kang Soon Hyoung Pyo Ken-ichi Anjyo & Sung Yong Shin 《Computer Graphics Forum》2001,20(3):132-141
Tour into the picture (TIP) proposed by Horry et al. 13 is a method for generating a sequence of walk-through images from a single reference picture (or image). By navigating a 3D scene model constructed from the picture, TIP produces convincing 3D effects. Assuming that the picture has one vanishing point, they proposed the scene modeling scheme called spidery mesh. However, this scheme has to go through major modification when the picture contains multiple vanishing points or does not have any well-defined vanishing point. Moreover, the spidery mesh is hard to generalize for other types of images such as panoramic images. In this paper, we propose a new scheme for TIP which is based on a single vanishing line instead of a vanishing point. Based on projective geometry, our scheme is simple and yet general enough to address the problems faced with the previous method. We also show that our scheme can be naturally extended to a panoramic image. 相似文献
96.
We present a real‐time method for rendering a depth‐of‐field effect based on the per‐pixel layered splatting where source pixels are scattered on one of the three layers of a destination pixel. In addition, the missing information behind foreground objects is filled with an additional image of the areas occluded by nearer objects. The method creates high‐quality depth‐of‐field results even in the presence of partial occlusion, without major artifacts often present in the previous real‐time methods. The method can also be applied to simulating defocused highlights. The entire framework is accelerated by GPU, enabling real‐time post‐processing for both off‐line and interactive applications. 相似文献
97.
Ha Yong Lee Young Ho Yu Young Cheol Lee Young Pyo Hong Kyung Hyun Ko 《Journal of Thermal Spray Technology》2004,13(2):184-189
Al + SiC, Al + Al2O3 composites as well as pure Al, SiC, and Al2O3 coatings were prepared on Si substrates by the cold gas dynamic spray process (CGDS or cold spray). The powder composition
of metal (Al) and ceramic (SiC, Al2O3) was varied into 1:1 and 10:1 wt.%, respectively. The propellant gas was air heated up to 330 °C and the gas pressure was
fixed at 0.7 MPa. SiC and Al2O3 have been successfully sprayed producing coatings with more than 50 μm in thickness with the incorporation of Al as a binder.
Also, hard ceramic particles showed peening effects on the coating surfaces. In the case of pure Al metal coating, there was
no crater formation on hard Si substrates. However, when Al mixed with SiC and Al2O3, craters were observed and their quantities and sizes depended on the composition, aggregation and size of raw materials. 相似文献
98.
Ligularia fischeri and its main flavonoids, hyperoside and 2″-acetylhyperoside, posses antioxidant properties. This study was carried out to investigate the contents of hyperoside and 2″-acetylhyperoside in L. fischeri by using high performance liquid chromatography (HPLC). An HPLC–photodiode array (PDA) detection method was established for the simultaneous determination of hyperoside and 2″-acetylhyperoside in L. fischeri. Two flavonoids were successfully separated in less than 20 min using an YMC RP 18 column. The mobile phase was composed of water (A) and acetonitrile (B) with isocratic elution system (23% B) at a flow rate of 1 mL/min. Their calibration curves showed good linear regression (r > 0.9992) within the test ranges. The method was validated for specificity, accuracy, precision, and limits of detection. The determined two compounds were well separated with a linear range of 18–180 μg/mL. The contents of hyperoside and 2″-acetylhyperoside were 0.387 ± 0.002 and 0.526 ± 0.006 mg/g in L. fischeri, respectively. 相似文献
99.
Characteristics of carbon nanotubes grown by mesh-inserted plasma-enhanced chemical vapor deposition
Ingoo Jang Hyung Soo Uh Hyun Jin Cho Wonhee Lee Jin Pyo Hong Naesung Lee 《Carbon》2007,45(15):3015-3021
Plasma-enhanced chemical vapor deposition (CVD) has the advantages of low temperature and vertical growth in synthesizing carbon nanotubes (CNTs), but has generally produced stubby CNTs, probably due to an ion bombardment effect. To suppress the ion bombardment, a metal mesh with the same electrical potential as that of the cathode was placed just above the substrate on the cathode. The anode was electrically grounded while the cathode and the mesh were both negatively biased, causing no plasma to occur below the mesh. The substrate was therefore separated from the plasma by the mesh so that the ion bombardment was suppressed. CNTs were grown on a 2 nm-thick Invar catalyst with different DC plasma powers of 0–112 W at 500 °C, 3.3 torr for 10 min, using C2H2 (28 sccm) and NH3 (172 sccm). Compared to CNTs grown with no mesh, these CNTs showed smaller diameters and greater lengths. As the plasma power decreased, the CNTs grown with mesh were thinner and longer and resembled those grown at a higher temperature by thermal CVD. Etching these CNTs by N2 plasma reduced their population density and considerably improved their field emission characteristics. 相似文献
100.