1,721,035 research outputs found
A magnetically coupled three-dimensional (terephthalato)manganese(II) network
No full textThis work was supported by the Korea
Science and Engineering Foundation and Samsung Advanced
Institute of Technology. We also thank Yaung Soo Kim of the
Korea Basic Science Institute for the measurement of the
magnetic susceptibility
Hydrogen- and covalent-bond-linked 3D manganese array
No full textSupport of this work by the Korea
Science and Engineering Foundation and Samsung Advanced
Institute of Technology is gratefully acknowledged
Size effect on the fiber strength of composite pressure vessels
No full textIn this study, experimental tests and an analytical approach are conducted to verify the size effect on the fiber strength of a composite pressure vessel. As an analytical method, the Weibull weakest link model and the sequential multi-step failure model are considered and mutually compared. In the case of carbon fiber tensile strength, there is no large difference between the analytical methods for the volumetric size effect. To verify the validity of the analytical approach, experimental tests were performed using fiber strand specimens, unidirectional laminate specimens and composite pressure vessels. Good agreement for fiber strength distribution was shown between the test data and predicted results. The volumetric size effect shows the clearly observed tendency towards fiber strength degradation with increasing stressed volume. Because the volumetric size effect depends on material and processing factors, the reduction of fiber strength due to the stressed volume shows different values according to the variation of material and processing conditions
The signal characteristics of reflected spectra of fiber Bragg grating sensors with strain gradients and grating lengths
No full textAmong the numerous types of fiber optic sensors, FBG sensors are currently the most actively studied sensors due to their good multiplexing capabilities. The demodulation method of FBG sensors is based on detecting the wavelength shift of their sensor peaks. Properties such as strain, temperature, etc. can be measured simply by detecting them. However, the signal stability of FBG sensors can be influenced by strain gradients induced by structural geometry or cracks on the surface when FBG sensors are embedded into or attached on the structure. In this study, the signal characteristics of reflected spectra of FBG sensors were verified under strain gradients and the correlation between the grating length of FBG sensors and strain gradients were investigated quantitatively. From the experimental results, the optimum working range of the FBG sensors, where FBG sensors could be used without split of the sensor peak, was shown when they were under strain gradients
Simultaneous Measurement of Strain and Temperature of Structures Using Fiber Optic Sensor
No full textThe first (mu-oxo)diferric chain complex: Structure and magnetic properties of [Fe-2(tren)(2)(mtm)O](n)(CF3SO3)(n)Cl-n
No full textSupport of this work by the Korea
Science and Engineering Foundation and Basic Science Research
Institute Program (Grant BSRI 94-3429) is gratefully
acknowledged
Ethylene-bridged pseudo-C-s symmetric ansa-zirconocene complexes: synthesis, structures and propylene polymerization behavior
No full textThe ethylene-bridged pseudo-C-s symmetric ansa-zirconocene complexes, (1-fluorenyl-2-cyclopentadienylethane)zirconium dichloride (5b), were synthesized and their molecular structures have been determined by single crystal X-ray diffraction studies. The complex 5a is very active toward propylene polymerization in the presence of methylaluminoxane (MAO), affording polypropylene with good syndiotacticity. In comparison with the known syndiotactic polypropylene catalytic system iPr(fluorenyl)(cyclopentadienyl)ZrCl2/MAO 5a/MAO system is better in thermal stability, higher in activity and lower in syndiotacticity under the identical polymerization conditions. On the other hand, 5b/MAO system shows low activity and produces nearly atactic polypropylene with low molecular weight, which could be attributed to the increased electron density and steric bulkiness around the metal center. (C) 1998 Elsevier Science S.A. All rights reserved.Korea Science and Engineering Foundation
and the Korea Advanced Industrial Technolog
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