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991.
Young Sang Cho Jeom Han Kim Seong Uk Hong Yuri Kim 《Renewable & Sustainable Energy Reviews》2012,16(5):3146-3153
The Life Cycle Assessment tool is used in the construction industry to assess the environmental impact and the resources that are used throughout the life span of a construction project, which consists of the raw material acquisition, production, design phase, construction phase, operation phase and the demolition and dismantling phase. The global community is taking immediate action to reduce the CO2 and green house gases (GHG) that are being produced due to global warming. The Kyoto protocol agreement has set binding targets for 37 industrialized countries and the European community to reduce their GHG emissions by an average of 5%, back to 1990 levels, within the years of 2008–2012.The global community is making many efforts to reduce CO2 and green house gases (GHG). The building construction industry is responsible for approximately 40% of the carbon dioxide emissions. There are currently more than four super tall, more than 100 story, high rise building construction projects in metropolitan Seoul, and this ranks Korea in the top four countries worldwide for the number of high rise buildings. Reducing the amount of structural steel in these high rise buildings by using an optimum structural design would reduce CO2 and green house gas (GHG) emissions. This aim of this study was to analyze the lateral load resisting structural systems in a high rise steel building in order to select the optimum structural system under the equivalent allowable lateral drift. The environmental impact was assessed using the LCA tool, and the results are discussed along with possible recommendations that may improve the current LCA tools. 相似文献
992.
Seok Su Sohn Seung Youb Han Sang Yong Shin Jin-ho Bae Kisoo Kim Nack J. Kim Hyoung Seop Kim Sunghak Lee 《Metals and Materials International》2012,18(4):597-606
In the present study, spiral piping was conducted on API X80 linepipe steel, and the outer and inner wall pipe yield strengths were measured. A low-cycle fatigue test was conducted on a leveled X80 steel sheet to simulate piping and flattening processes, and the strain hardening and Bauschinger effects, induced from different strain histories, were evaluated and combined using Swift??s equation and the Bauschinger stress parameter, respectively. By analyzing the stress-strain curves obtained from the low-cycle fatigue test, the yield strengths of the outer and inner walls were estimated to be 592 MPa and 492 MPa, respectively, which are lower by 20?C80 MPa than that of the actual pipe used. Possible reasons for measured and estimated yield strength differences could be the simulation determining procedure of the pre-strain and Bauschinger stress parameters, preposition of same strain hardening behavior depending on strain history, and pre-strain differences depending on thickness location in the steel sheet during piping. 相似文献
993.
994.
Sang Heon Han Daejun Chang 《International Journal of Heat and Mass Transfer》2012,55(15-16):4079-4087
A 3D unsteady numerical simulation of a reheating furnace was performed to obtain the optimal slab residence time. Too long residence time decrease the efficiency of the reheating furnace, whereas too short residence time cannot satisfy the required heating quality of a slab. The total five cases of residence times – 6032 s, 6496 s, 6960 s, 7424 s and 7888 s – were investigated for the optimum residence time analysis with the two slab requirements, those of emission temperature and uniformity. In this study, the slab emission temperature should be in the range between 1373 K and 1573 K. The skid mark severity of an emitted slab should be lower than 50 K to satisfy the uniformity requirement. The numerical analysis was done for the identical geometry and operating condition of the reheating furnace using FLUENT. Slabs were assumed to move very quickly that it took no time for them to move next positions. The quick movements of slabs were processed with the own developed User-Defined Function program. Among the five cases of residence times, the residence time of 7427 s turned out to be most efficient. 相似文献
995.
Li-xia Sang Zhang Zhi-yu Bai Guang-mei Du Chun-xu Ma Chong-fang 《International Journal of Hydrogen Energy》2012,37(1):854-859
The present work investigates the photoelectrochemical behavior of nanotubular N/C-TiO2 electrode for hydrogen production. Via the sonoelectrochemical anodization process of 1 h, N-containing TiO2 based nanotube arrays(N-TNT) with the length of about 650 nm were fabricated in fluoride aqueous solution added 0.25 M NH4NO3; C-containing TiO2 based nanotube arrays(C-TNT) with the length of about 2 μm were prepared in fluoride ethylene glycol solution. In virtue of the longer tubes with the larger surface areas, C-TNT can harvest more light and produce more photoactive sites than N-TNT, which also made the charge transfer resistance in C-TNT larger than that in N-TNT. Considered the more negative flat band potential of C-TNT, C-TNT has the smaller energy barrier and the better photoelectrochemical activity. It may be attributed to the appropriate defect concentration gradient owing to the modification of C element. Under UV-vis light (320-780 nm) irradiation, the average hydrogen generation rate of C-TNT was 282 μL h−1 cm−2. The surface properties and near-surface properties of the resultant electrode were synthetically analyzed by using UV-vis diffuse reflectance spectra(DRS), field emission scanning electron microscopy (FESEM), I-t curves, and electrochemical impedance spectroscopy (EIS) techniques. 相似文献
996.
The photovoltaic properties of a series of low band-gap conjugated copolymers, in which alkyl side chains were substituted at various positions, were investigated using donor-acceptor (D-A) conjugated copolymers consisting of a cyclopentadithiophene derivative and dithienyl-benzothiadiazole. The base polymer, which has no alkyl side chains, yielded promising power conversion efficiency of 3.8%. Polymers with alkyl side chains, however, exhibited significantly decreased performance. In addition, the effects of processing additive became negligible. The results indicate that substituted side chains, which were introduced to improve solubility, critically affected the optical and electronic properties of D-A conjugated copolymers. Furthermore, the position of the side chain was also very important for controlling the morphological properties of the D-A conjugated copolymers. 相似文献
997.
J.P. Beardmore A.J. PalmerC.G.C.H.M. Fabrie K.A.H. van LeeuwenR.T. Sang 《Thin solid films》2012,520(7):2414-2417
In this paper we present the first characterisation of growth of a carbonaceous film on a silicon substrate exposed to a metastable atom beam using an in situ rotating polariser ellipsometer. The initial deposition of oil due to a background partial pressure in vacuum is investigated. Subsequent exposure of the deposited oil to a high flux metastable neon (Ne*) beam results in cross-linking of the oil film, creating a polymerised carbonaceous layer. Values for the mean residence time, polymerisation cross-section, and desorption cross-section are calculated and compared to similar studies performed for ion bombardment. Simple estimates can provide reasonable values for application of the theory to other systems. 相似文献
998.
Myung Soo Lee Sang Han Park Mann-Ho Cho Hyoungsub Kim 《Materials Research Bulletin》2012,47(6):1423-1427
The microstructural and electrical properties of solution-deposited GdCeOx dielectric thin films with different mixing ratios were studied. The Ce incorporation enhanced the degree of crystallization and the refractive index of the Gd2O3 film, reduced the hysteresis and increased the dielectric constant. According to reflective electron energy loss spectroscopy and X-ray photoelectron spectroscopy analyses, the bandgap of the GdCeOx film gradually decreased with increasing Ce/(Gd + Ce) atomic ratio, which was primarily affected by the reduction of the valence band offset. 相似文献
999.
Euh Duck Jeong Hyun Ju Han Ok Sang Jung Myoung Gyu Ha Chil Hoon Doh Min Ji Hwang Ho-Soon Yang K.S. Hong 《Materials Research Bulletin》2012,47(10):2847-2850
Pure and metal (Cu, Al, Sn, and V)-doped Li4Ti5O12 powders are prepared with solid-state reaction method. The effects of dopants on the physical and electrochemical properties are characterized by using TGA, XRD, and SEM. Compared with pure Li4Ti5O12, metal-doped Li4Ti5O12 powders show structural stability and enhanced lithium ion diffusivity brought by doped metal ions. Voltage characteristics and initial charge–discharge characteristics according to the C rates in pure and metal-doped Li4Ti5O12 electrode materials are studied. Pure Li4Ti5O12 powder shows a relatively good discharge capacity of 164 mAh/g at a rate 0.2C, and some of metal-doped Li4Ti5O12 powders show higher discharge capacities. Metal-doped Li4Ti5O12 powders are promising candidates as anode materials for lithium-ion batteries. 相似文献
1000.
For dye-sensitized solar cells application, in this study, we have synthesized TiO2 thin films at deposition temperature in the range of 300–750 °C by metalorganic chemical vapor deposition (MOCVD) method. Titanium(IV) isopropoxide, {TIP, Ti(OiPr)4} and Bis(dimethylamido)titanium diisopropoxide, {BTDIP, (Me2N)2Ti(OiPr)2} were used as single source precursors that contain Ti and O atoms in the same molecule, respectively. Crack-free, highly oriented TiO2 polycrystalline thin films with anatase phase were deposited on Si(1 0 0) with TIP at temperature as low as 450 °C. XRD and TED data showed that below 500 °C, the TiO2 thin films were dominantly grown in the [2 1 1] direction on Si(1 0 0), whereas with increasing the deposition temperature to 700 °C, the main film growth direction was changed to [2 0 0]. Above 700 °C, however, rutile phase TiO2 thin films have only been obtained. In the case of BTDIP, on the other hand, only amorphous film was grown on Si(1 0 0) below 450 °C while a highly oriented anatase TiO2 film in the [2 0 0] direction was obtained at 500 °C. With further increasing deposition temperatures over 600 °C, the main film growth direction shows a sequential change from rutile [1 0 1] to rutile [4 0 0], indicating a possibility of getting single crystalline TiO2 film with rutile phase. This means that the precursor together with deposition temperature can be one of important parameters to influence film growth direction, crystallinity as well as crystal structure. To investigate the CVD mechanism of both precursors in detail, temperature dependence of growth rate was also carried out, and we then obtained different activation energy of deposition to be 77.9 and 55.4 kJ/mol for TIP and BTDIP, respectively. Also, we are tested some TiO2 film synthesized with BTDIP precursor to apply dye-sensitized solar cell. 相似文献