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981.
Jung-Seok Kim Hyuk-Jin Yoon Woo-Geun Lee 《Journal of Mechanical Science and Technology》2016,30(12):5439-5446
In this study, the dynamic characteristics of three different bogie configurations, a conventional Steel bogie (SB), a composite bogie without primary suspension (CB1), and a composite bogie with primary suspensions of conical rubber type (CB2), were compared. The CB1 shows the highest critical speed while the CB2 shows the lowest. The SB configuration showed the highest ride index value while the CB2 showed the lowest. Both of the composite configurations showed better ride comfort index than that of the steel configuration. The trend of the derailment index was opposite to that of the critical speed. In the derailment index measuring test, the CB1 bogie configuration had a 12.3 % higher derailment index than that of the SB. These results show good agreement in overall trends with the simulation results. 相似文献
982.
Suk Hoo Yoon Sun Ki Kim Kil Hwan Kim Tai Wan Kwon Yau Kun Teah 《Journal of the American Oil Chemists' Society》1987,64(6):870-873
Rice bran oil and double fractionated palm olein (DF palm olein) were heated at 180 C for 50 hr to measure lipid deterioration
in the oils. Free fatty acid content of both oils increased during heating; however, iodine value and smoke point decreased.
Solid fat contents of both oils were unaffected by heating time. Cloud point of rice bran oil was much lower than that of
palm olein. Color of oils changed gradually to dark brown from light yellow with increased heating time. Absolute content
of polyunsaturated fatty acid, such as linoleic acid, reduced more than that of monounsaturated fatty acid, such as oleic
acid, in both oils. In both oils, iodine value correlated very well with linoleic acid content, with correlation coefficient
higher than 0.96. 相似文献
983.
Myung-Chul Han Keum Shik Hong Joòngsun Yoon Suk Lee 《Journal of Mechanical Science and Technology》1997,11(1):1-9
Decentralized robust control of strongly interconnected uncertain systems is addressed in this paper. The uncertainties we consider here may include parameter uncertainty and input disturbance that may be nonlinear and (possibly fast) time-varying. We show specially how both internal and external uncertainties are taken into considerations. This work covers a broad class of large-scale systems since the current consideration renders all previous settings as special cases. Stability analysis with the proposed controllers is provided. 相似文献
984.
Byungjun Kang Kyung Dong Lee Jong-gun Lee Jae-Wook Choi Sam S. Yoon Yoonmook Kang Hae-seok Lee Donghwan Kim 《Journal of Thermal Spray Technology》2016,25(3):465-472
In this study, we investigated cold-sprayed copper as a front contact for crystalline silicon solar cells. Copper powder was deposited on a monocrystalline silicon wafer with variation of the particle velocity during deposition. The particle velocity was varied by varying the heating temperature from 250 to 400 °C using a gas pressure of 0.45 MPa. The particle velocities were calculated using empirical equations, and were found to increase with an increase in the carrier gas temperature. Grid patterns were formed on a phosphorus-doped n-type emitter of a p-type silicon substrate. The electrode thickness increased with increasing particle velocity. The electrical properties of the grids were evaluated using the transfer length method. The specific contact resistance of the n-type emitter was in the range of 2.6-26.4 mΩ-cm2. Damage to the p-n junction was investigated via minority carrier lifetime measurement of the substrate. The copper-silicon interface was evaluated using transmission electron microscopy. The contact properties were affected by the interface conditions. 相似文献
985.
Seong-Ho Choi Dong-Won Jung Sung-Ook Yoon Soon Park Eun-Suok Oh Junbom Kim 《Metals and Materials International》2011,17(5):811-816
To enhance the performance of a polymer electrolyte membrane fuel cell (PEMFC), a Pt catalyst was supported on carbon nanotubes
(CNTs) and the optimum content of Nafion ionomer in the Pt/CNT electrode was examined by cell performance tests, cyclic voltammetry,
and electrochemical impedance spectroscopy. The amount of the Pt catalyst supported on the CNTs was 34 wt.%. The Nafion content
significantly changed the protonic and electronic conductivities as well as the mass transfer properties. As such, the performance
of the cell was highly dependent on the content of Nafion ionomer. The results of the cell performance tests revealed that
the optimum content of Nafion ionomer in the Pt/CNT electrode was about 20 wt.%. 相似文献
986.
In the present study, two Ti-based amorphous matrix composites containing ductile dendrites dispersed in an amorphous matrix were fabricated by a vacuum arc melting method, and deformation mechanisms related to the improvement of strength and ductility were investigated by focusing on how ductile dendrites affected the initiation and propagation of deformation bands, shear bands or twins. Ti-based amorphous matrix composites contained 70–73 vol.% coarse dendrites of size 90–180 μm, and had excellent tensile properties of the yield strength (1.2–1.3 GPa) and elongation (8–9%). The Ta-containing composite showed strain hardening after yielding, and reached fracture without showing necking, whereas necking occurred straight after yielding without strain hardening in the Nb-containing composite. The improved tensile elongation and strain hardening behavior was explained by the homogeneous distribution of dendrites large enough to form deformation bands or twins, the role of β phases surrounding α phases to prevent the formation of twins, and deformation mechanisms such as strain-induced β to α transformation. 相似文献
987.
News
Highlights from recent literature 相似文献988.
Nano-sized silicon particles were uniformly coated onto a natural graphite surface by a 1 ton/month-based semi-mass production ball milling method in order to prepare Si-based anodes for Li ion batteries. The structure, surface morphology and Si coating properties of the as-synthesized powders were analyzed by XRD, Raman, SEM, TEM and EDS mapping tools. The initial gravimetric discharge capacity of the Si-coated graphite measured using a half cell was 761 mAh/g at a rate of 0.2 C. Additionally, the discharge capacity retention of a full cell system was 71.4% at a 1 C rate even after 300 cycles as well as 96.6% of initial coulombic efficiency. The cycled composite powders were further analyzed by SEM and EDS mapping techniques. This method is proposed for commercial extension to the manufacture of lithium secondary batteries. 相似文献
989.
Kum Hee Lee Hyun Ju Kang Seok Jae Lee Ji Hyun Seo Young Kwan Kim Seung Soo Yoon 《Synthetic Metals》2011,161(11-12):1113-1121
A series of new iridium complexes with 5-acetyl-2-phenylpyridine derivatives as ligands was developed. The complexes exhibited high EL performance when applied to OLEDs. These materials showed red emission with a peak at 575–636 nm. In particular, one of the devices in this study showed a maximum luminous efficiency, maximum power efficiency, external quantum efficiency and CIE coordinates of 29.0 cd/A, 6.13 lm/W, 8.86% at 20 mA/cm2 and (0.57, 0.43) at 10 V, respectively. In addition, a deep red OLED with CIE coordinates of (0.67, 0.32) at 10 V exhibited a maximum luminous efficiency, maximum power efficiency and external quantum efficiency of 5.61 cd/A, 1.02 lm/W and 5.35% at 20 mA/cm2, respectively. 相似文献
990.
Dongbo Mi Ji-Hoon Kim Sung Cheol Yoon Changjin Lee Jin-Kyun Lee Do-Hoon Hwang 《Synthetic Metals》2011,161(13-14):1330-1335
A novel carbazole-group-containing fullerene derivative (CBZ-C60) with good solubility in common organic solvents was synthesized. This derivative was analyzed by using many techniques such as NMR, FAB-MS, FTIR and UV–vis absorption spectroscopy. Further, bulk heterojunction photovoltaic devices were fabricated. Since the LUMO energy level of CBZ-C60 was higher than that of fullerene, the open-circuit voltage (Voc) of devices based on CBZ-C60 was higher than that of devices based on fullerene. The power-conversion efficiency was highest for devices with composite thin films that have P3HT/CBZ-C60 composition ratios of 1:1 and were annealed at 150 °C for 10 min. The maximum Voc, short-circuit current density, and PCE of the best device were 0.64 V, 2.32 mA/cm2, and 0.48%, respectively. 相似文献