2,848 research outputs found
Shear Behavior and Performance of Deep Beams Made with Self-Compacting Concrete
No full textAn experimental study was carried out to evaluate fresh properties of a moderately high-strength (high-flowing) self-compacting concrete (SCC) and to investigate shear behavior and performance of deep beams made with SCC. Fresh and hardened properties of normal concrete (NC) and SCC were evaluated. The workability and compacting ability were observed based on casting time and number of surface cavities, respectively. Four-point loading tests on four deep beams (two made with SCC and two with NC) were then conducted to investigate their shear behavior and performance. Shear behavior and performance of beams having two different web reinforcements in shear were systematically investigated in terms of crack pattern, failure mode, and load-deflection response. It was found from the tests that the SCC specimen having a normal shear reinforcement condition exhibited a slightly higher load carrying capacity than the corresponding NC specimen, while the SCC specimen having congested shear reinforcement condition showed a similar load carrying capacity to the corresponding NC specimen. In addition, a comparative study between the present experimental results and theoretical results in accordance with ACI 318 (Building Code Requirements for Reinforced Concrete (ACI 318-89) and Commentary-ACI 318R-89, 1999), Hsu-Mau's explicit method (Hsu, Cem Concr Compos 20: 419-435, 1998; Mau and Hsu, Struct J Am Concr Inst 86: 516-523, 1989) and strut-and-tie model suggested by Uribe and Alcocer (2002) based on ACI 318 Appendix A (2008) was carried out to assess the applicability of the aforementioned methods to predict the shear strength of SCC specimens.
Iridium and Ruthenium oxide miniature pH sensors: long-term performance
No full textThe characteristics of electrodeposited Iridium oxide films (EIROF), and Ruthenium oxide films (RUOF) under normal and annealed conditions have been investigated. RUOFs were sputter deposited onto a substrate whilst EIROF sensors were made by electrodeposition. The adhesion of the RUOF sensors was investigated on Platinum and Titanium surfaces. The electrical impedance of the two metal oxides was measured in PBS demonstrating that both films have up to a 100 fold higher electrical double layer capacitance than bright Platinum electrodes. The EIROF films show super-Nernstian response, but the formal potential shows a continuous drift with time of approximately 2 mV day-1, measured over 40 days. Both RUOF sensors show approximately Nernstian behaviour. Short term pH precision of the annealed RUOF falls within a confidence interval of ± 0.1 pH, and stability is maintained within a confidence of ± 0.24 pH for up to 147 days. The un-annealed RUOF maintains the same precision but only for 20 days. Compared to EIROF sensors, no drift correction is required for the annealed RUOF making this metal oxide suitable for long term measurements where re-calibration is not possible
Incommensurate Structural Correlations in the Disordered Spin-Dimer State Induced by X-ray and Electron Irradiation in CuIr2S4
No full textThe Impact of Free Trade Agreements (FTAs) on Business in the Republic of Korea
No full textThe Republic of Korea (hereafter Korea) continues to promote an open-trade system via the conclusion of free trade agreements (FTAs), arguing that Korean enterprises will obtain considerable business opportunities under the FTAs the government has implemented. However, the FTAs that are currently being implemented in Korea are said to be beneficial only to some enterprises. This study presents new evidence from a survey conducted from July–August 2008 on 120 Korean firms. The paper explores critical questions regarding the utilization of FTAs, their perceived costs and benefits, perceptions of multiple rules of origin (ROOs), and policy and institutional support mechanisms for FTAs. One of the key findings is that most of the currently implemented FTAs in Korea were concluded with small- and medium-sized developing countries. Moreover, within these FTAs, the range of preferential tariffs is not very broad in scope; as such, only one out of five enterprises was found to be utilizing them. However, since the conclusion of FTAs with the United States and the European Union, Korean businesses have become very interested in utilizing those respective FTAs. The government should make efforts for early implementation of these FTAs. In the FTAs concluded by Korea, ROOs are strict and complicated. In future FTAs, a more neutral and lenient form of ROOs should be adopted.free trade agreement korea; korea fta impact; korea fta trade business
Magnetic Island Structures Associated with Kinetic Alfvén Solitary Wave in Two-fluid Plasma
No full textWe investigate the formation of magnetic islands and the onset of tearing instability within kinetic Alfv & eacute;n solitary waves in a two-fluid space plasma. These localized structures, featuring internal magnetic shear, naturally support magnetic reconnection processes analogous to tearing modes in magnetically confined fusion plasmas. Treating the solitary wave as a quasi-static background equilibrium, we analyze the resulting topological modifications by making use of the magnetic flux function, in analogy with tokamak plasmas. We find that the spatial size of the magnetic island scales with the square root of the magnetic flux perturbation. Introducing the tearing stability index Delta ' , we derive the growth rate of the tearing mode using a resistive magnetohydrodynamic framework. Our analysis reveals that tearing modes grow only when the mode's wavenumber exceeds the inhomogeneity scale, becoming marginally stable when the two are comparable. The emergence of magnetic islands has significant implications for cross-field particle transport, turbulence, and acceleration. In particular, the electron diffusion across magnetic fields may be governed by the island size rather than the Larmor radius, potentially accounting for anomalous transport. Furthermore, in certain regimes, unbounded island growth may signal the collapse of the solitary wave structure, enabling a large-scale transfer of magnetic energy to particle energy. These results suggest a unifying mechanism connecting magnetic reconnection in space plasmas with tearing instabilities in laboratory fusion plasmas.
Microscopic electronic phase separation and metal-insulator transition in Nd0.5Sr0.5MnO3
No full textMoldable and Particulate Bone Material in Alveolar Ridge Preservation: A Multicenter Randomized Controlled Trial
No full textPolaron Bands in the Far- and Mid-Infrared Spectra of e-doped Cuprates
No full textEditors E. K. H. Salje, A. S. Alexandrov, and W. Y. Liang (Cambridge university Press, Cambridge
Free-form sketching of self-occluding objects
No full textWhen 3D objects occlude each other or self-occlude, their drawings typically Consist of a set of contours that might partially overlapor self-overlap. The authors' method infers the hiciden partsof contours and creates a smooth 30, shape matching those contours by solving a set of optimization problems.We thank Sung-Yong Shin, Young-Sang Cho, and
Otfried Cheong (Korea Advanced Institute of Science
and Technology) for their invaluable advice and useful
comments. This work was supported by the Korea
Research Foundation Grant funded by the Korean Government
(KRF-2006-531-D00033), and author Cordier
was supported by the Graduate School of Culture Technology
(Ministry of Culture and Tourism of Korea)
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