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排序方式: 共有1465条查询结果,搜索用时 125 毫秒
101.
Jae-Chul Lee Ho-In Lee Jae-Pyoung Ahn Jae-Hyeok Shim Zhongliang Shi 《Metallurgical and Materials Transactions A》2001,32(6):1541-1550
A methodology to control interfacial microstructures, while suppressing formation of Al4C3 in wrought Al alloy composites reinforced with SiC, was demonstrated. Thermodynamic calculations were carried out to elucidate
how one can select process parameters in terms of alloy composition and fabrication temperature to obtain intended interfaces.
Experimental verifications were conducted using scanning electron microscopy (SEM) and transmission electron microscopy (TEM)
to validate calculated results. The reaction mechanisms for forming various interfaces were identified both theoretically
and experimentally. Evaluations of the interfacial bonding strengths and interfacial stability at elevated temperatures were
also carried out for various interface types. 相似文献
102.
Md. Mominul Islam Sheikh Chul-Hwan Kim Ji-Young Lee Sung-Ho Kim Gyeong-Chul Kim Ji-Young Lee Sung-Woong Shim Jae-Won Kim 《Food and Bioproducts Processing》2013,91(1):60-65
Waste money bills that are no longer legal tender are non-recyclable and are usually destroyed. In this study, we used this cellulose-rich material for bioethanol fermentation for the first time. Glucose production was enhanced by using diluted H2SO4 during pretreatment. Different incubation periods were tested for saccharification and subsequent bioethanol fermentation. The highest yield of glucose (41.90 mg/ml) was shown to increase with 27.20% and 25.90% respectively by increasing the reaction period by 30 min and by increasing the acid concentration by 0.5%. Bioethanol production was enhanced by adding 0.4 mM benzoic acid under anoxic condition. In accordance with three different conditions, the highest amount of bioethanol (22.01 mg/ml) was obtained and bioethanol fermentation was increased by 59.38%, 110.02% and 64.13% respectively with 30 min of reaction periods, 0.5% of acid concentrations and under anoxic condition with benzoic acid. This procedure for the production of bioethanol from a waste material would reduce waste money bill management costs and make a profit from ethanol. 相似文献
103.
Kwangsoo No Dae-Shik Chung Jae-Myung Kim Hye-Young Kim Wonbaek Kim Gunchoo Shim 《Journal of Materials Science》1991,26(13):3593-3598
YBa2Cu3O
x
superconductor was synthesized using Y2BaCuO5, BaCuO2, and CuO powder mixture. Reaction temperatures were identified using differential thermal analysis (DTA) and thermogravimetry (TG) for syntheses of precursor powders and the powder mixtures. Appropriate reaction temperatures for Y2BaCuO5 and BaCuO2 precursor powders were 950 and 930°C, respectively. Two endothermic reactions involving melt formations were identified on the DTA and TG curves of the powder mixture, and the liquid increased the reactivity of the YBa2Cu3O
x
formation. Powder mixture samples were sintered at various temperatures ranging from 880 to 1000°C. Microstructural and X-ray powder diffraction studies showed YBa2Cu3O
x
and impurities to be formed in the samples sintered at various temperatures. The samples sintered at 990 and 1000°C showed dense microstructures. The critical temperature was 84 K for the sample sintered at 880°C and rose to 92 K as the sintering temperature increased. 相似文献
104.
Vilmos Galamb Sang Chul Shim Fazle Sibtain Howard Alper 《Israel journal of chemistry》1985,26(3):216-218
The intermediates mentioned in the title are probably involved in the hydrogenation of olefins and dienes; bidentate phosphine and arsine cobalt complexes are useful reagents for these reactions. 相似文献
105.
Jaewon Choi Jeongwoo Lee Jinsub Choi Dongsoo Jung Sang Eun Shim 《Synthetic Metals》2010,160(13-14):1415-1421
Herein, PEDOT:PSS/PVP nanofibers were produced by electrospinning. The presence of PEDOT:PSS in the nanofibers was confirmed by FT-Raman spectroscopy. The applied voltage-dependent diameter of PEDOT:PSS/PVP nanofibers was observed. Also, sensing behaviors of electrospun PEDOT:PSS/PVP nanofibers were explored by measuring its response upon cyclic exposure to organic vapours such as ethanol, methanol, THF, and acetone at room temperature. When PEDOT:PSS/PVP nanofibers were exposed to each solvent, the protic and aprotic solvents resulted in opposite electrical responses. These findings exhibit that electrospun PEDOT:PSS/PVP nanofibers are the promising candidate for the organic vapour sensing material. 相似文献
106.
Jong Duk Lee Byung Chang Shim Hyung Soo Uh Byung-Gook Park 《Electron Device Letters, IEEE》1999,20(5):215-218
This letter reports the surface morphology and current-voltage (I-V) characteristics of single-crystal silicon (c-Si), polycrystalline silicon (poly-Si), and amorphous silicon (a-Si) field emitter arrays (FEAs). As-deposited a-Si film has a smoother surface than poly-Si film. The surface morphology of the a-Si remains smooth even after phosphorus doping and oxidation at 950°C to be improved in emission characteristics, i.e., smaller anode current deviation among arrays smaller gate current, and higher failure voltage than those of poly-Si FEAs. Such improved characteristics can be explained by the smooth surface morphology which is kept during doping and oxidation. The surface roughness and emission characteristics of a-Si FEAs are comparable to those of c-Si FEAs 相似文献
107.
Gyu Bo Kim Jae Young Shim Seung Wan Cho Young June Chang Chung Hwan Jeon 《Journal of Mechanical Science and Technology》2008,22(6):1154-1162
With environmental concerns over emitted particulate matters(PM) from combustion systems, various researches have been conducted
on reduction and measurement techniques of particulate matters. The LII analysis results from numerical models and experiments
in an ethylene/air laminar diffusion flame at elevated pressure up to 2.0 MPa with laser fluence 0.07 J/cm2, detection wavelength 400 nm were compared to validate a modified LII numerical model. The lifetime of the LII signal decreased
as the elevated pressure increased, so that LII decay time also decreased in both results. In the aspect of heat transfer
mechanism, it becomes earlier that dominant conduction starts. This shows that the results matched well under the pressure
conditions. It is concluded that the LII numerical model could be applied to decide particle size in TIRE-LII at the high-pressure
condition. 相似文献
108.
Yuvaraj Haldorai Won Seok Lyoo Seok Kyun Noh Jae-Jin Shim 《Reactive and Functional Polymers》2010,70(7):393-399
This report describes the novel preparation of silica/polystyrene (SiO2/PS) core–shell composite nanospheres by in situ radical dispersion polymerization in an ionic liquid (IL). Silica nanoparticles were first surface modified by the silane coupling agent methacryloxypropyltrimethoxysilane (MPTMS), which is capable of copolymerizing with styrene and provided a reactive CC bond. Transmission electron microscopy (TEM) revealed core–shell morphology with smooth surfaces. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that almost all of the SiO2 nanoparticles were encapsulated by the polymer. The composite particles were also analyzed by FT-IR spectroscopy and thermogravimetric analysis (TGA). In principle, this simple and environmentally-friendly synthetic procedure can be employed to prepare other inorganic oxide-containing polymer composites. 相似文献
109.
A 2-D device simulation for organic thin-film transistors (OTFTs) was carried out to reveal the characteristic difference between staggered and planar structures. Assuming the OTFT with Schottky barrier contact, the staggered-structure TFT has more current flow, bigger field-effect mobility, and lower contact resistance than the planar structure. The simulation results indicate that the source electrode of the staggered structure has better ability to supply the current than that of the planar structure. 相似文献
110.
M. Shamshi Hassan M. Shaheer Akhtar Kyung-Bo Shim O-Bong Yang 《Nanoscale research letters》2010,5(4):735-740
Highly crystalline Pr6O11 nanorods were prepared by a simple precipitation method of triethylamine complex at 500°C. Synthesized Pr6O11 nanorods were uniformly grown with the diameter of 12–15 nm and the length of 100–150 nm without any impurities of unstable
PrO2 phase. The Pr6O11 nanorod electrodes attained a high electrical conductivity of 0.954 Scm−1 with low activation energy of 0.594 eV at 850°C. The electrochemical impedance study showed that the resistance of electrode
was significantly decreased at high temperature, which resulted from its high conductivity and low activation energy. The
reduced impedance and high electrical conductivity of Pr6O11 nanorod electrodes are attributed to the reduction of grain boundaries and high space charge width. 相似文献