• Computers and Concrete
• /
• v.18 no.2
• /
• pp.179-199
• /
• 2016

The aim of this study is to investigate arrival direction effects of travelling waves on non-linear seismic response of arch dams. It is evident that the seismic waves may reach on the dam site from any direction. Therefore, this study considers the seismic waves arrive to the dam site with different angles, ${\theta}=0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $75^{\circ}$, and $90^{\circ}$ for non-linear analysis of arch dam-water-foundation interaction system. The N-S, E-W and vertical component of the Erzincan earthquake, on March 13, 1992, is used as the ground motion. Dam-water-foundation interaction is defined by Lagrangian approach in which a step-by-step integration technique is employed. The stress-strain behavior of the dam concrete is idealized using three-dimensional Drucker-Prager model based on associated flow rule assumption. The program NONSAP is employed in response calculations. The time-history of crest displacements and stresses of the dam are presented. The results obtained from non-linear analyses are compared with that of linear analyses.

• Journal of Hydrospace Technology
• /
• v.1 no.1
• /
• pp.1-13
• /
• 1995

Vortex shedding from a circular cylinder is simulated by means of the discrete vortex method. The shear layer emanating from the separation point is approximated as a sheet vortex which is in turn represented by a sequence of discrete vortices. The strength of these vortices is calculated from the vorticity shedding rate and introduced at a small distance off the side ($\Theta=\pm\pi/2$) of the cylinder surface in regular time step. Sheet vortex cutting, rediscretization and replacement of vortex by vortex segment are put to use to enhance stability of the sheet vortex evolution. The simulated vortex distribution pattern very well reproduces structure like the Karman vortex street. However, as for the force coefficients, the qualitative properties are correctly predicted but some more improvements are needed for the quantitative accuracy.

• Journal of Ship and Ocean Technology
• /
• v.12 no.2
• /
• pp.1-15
• /
• 2008

The main idea of this paper introduce stochastic structural parameters and random dynamic excitation directly into the dynamic functional variational formulations, and developed the nonlinear dynamic analysis of a stochastic variational principle and the corresponding stochastic finite element method via the weighted residual method and the small parameter perturbation technique. An interpolation method was adopted, which is based on representing the random field in terms of an interpolation rule involving a set of deterministic shape functions. Direct integration Wilson-${\theta}$ Method was adopted to solve finite element equations. Numerical examples are compared with Monte-Carlo simulation method to show that the approaches proposed herein are accurate and effective for the nonlinear dynamic analysis of structures with random parameters.

• Journal of the Korean Magnetics Society
• /
• v.5 no.5
• /
• pp.627-630
• /
• 1995

BaM films have a lot of advantage of chemical stability and mechanical stability as compared with a metallic thin film. In this paper, (Ba.Pb)M films have been prepared by using dc magnetron sputtering system and the dependences of their crystallographic characteristics and magnetic properties on oxygen pressure($Po_{2}$) were studied. The films prepared at $Po_{2}$ of around 0.02mTorr exhibit a fine particle-like structure and ${\Delta}{\theta}_{50}$ is as small as $1^{\circ}$. $Hc_{\bot},\;Hc_{//}$ and Ms of (Ba.Pb)M films are 700-800Oe, 200Oe and 180-230emu/cc, respectively.

• Structural Engineering and Mechanics
• /
• v.69 no.3
• /
• pp.327-334
• /
• 2019

The purpose of this paper is to investigate the hygrothermal effects on the behavior of reinforced-concrete beams strengthened by bonded composite laminate plates (${\theta}n/90m)s$. This work is based on a simple theoretical model to estimate the interfacial stresses developed between the concrete beam and the composite with taking into account the hygrothermal effect. Fibre orientation angle effects of number of $90^{\circ}$ layers and effects of plate thickness and length on the distributions of interfacial stress in the concrete beams reinforced with composite plates have also been studied.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.825-826
• /
• 2016

최근 뇌파에 대한 연구가 아주 활발하게 진행되고 있다. 이러한 뇌파를 분석하기 위해서는 뇌파센서를 이용하여 뇌파를 수집하고 뇌파의 주파수 분석 등을 이용하여 뇌파를 분석할 수 있다. 이러한 분석을 위하여 본 논문에서는 NeuroSky 사의 mindwave mobile 뇌파 센서를 이용하여 뇌파를 수집하여 집중도를 분석하였다. 사람 사이에 교류하고 소통하는 과정에서 뇌파의 공명 현상 같은 현상이 발생한다고 한다. 또한 보통의 경우 어떤 일을 할 때, 많은 사람의 응원을 받으면 응원을 받지 않는 경우보다 잘 할 수 있는 경우가 많다. 여러 사람의 응원이 한 사람의 집중도에도 영향을 미치는 지 실험을 통하여 분석하였다. 실험결과 한사람이 집중할 경우보다 여러 사람이 같이 집중할 때 집중도가 향상되는 것을 알 수 있었다.

• Bulletin of the Korean Chemical Society
• /
• v.6 no.4
• /
• pp.222-224
• /
• 1985

The crystal structure of sulindac, $C_{20}H_{17}Fo_3S$, one of the nonsteroid antiinflammatory agents, has been determined by the X-ray diffraction techniques using diffractometer data obtained by the $\varpi-2{\theta}$ scan technique with Cu $$K_{\alpha}$$ radiation from a crystal with space group symmetry Pbca and unit cell parameters a = 8.166(1), b = 18.291(8), c = 23.245(10) ${\AA}.$ The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.11 for the 1153 observed reflections. The carboxyl group is nearly perpendicular to the indenyl ring as observed in indomethacin. The dihedral angle between the indenyl and phenyl rings is $35^{\circ}while$ the corresponding angle in indomethacin is $67^{\circ}.$ Crystal packing consists of a hydrogen bond and partial ring stacking between the indenyl rings.

• Bulletin of the Korean Chemical Society
• /
• v.3 no.4
• /
• pp.162-165
• /
• 1982

The rate constants of the nucleophilic addition of thioglycolic acid to the derivatives $(H,\;p-CH_3,\;p-CH_3O,\;p-Cl,\;p-NO_2)$ of ${\beta}$-nitrostyrene were determined by ultraviolet spectrophotometry. The rate equations which can be applied over a wide pH range were obtained. Therefrom a reaction mechanism was proposed. Above pH 8.5 sulfide anion adds to the double bond (Michael type addtion). However, below pH 8.5, the neutral molecule and $HSCH_2COO^{\theta}$ add to the double bond.

• Bulletin of the Korean Chemical Society
• /
• v.5 no.4
• /
• pp.158-162
• /
• 1984

The crystal structure of chloramphenicol base, $C_9H_{l2}N_2O_4$, the deacylated base of antibiotic chloramphenicol, has been determined by X-ray diffraction techniques using diffractometer data obtained by the ${\omega}-2{\theta}$ scan technique with CuK${\alpha}$ radiation from a crystal with space group symmetry $P2_12_12_1$ and unit cell parameters a = 22.322(6), b = 7.535(6), c = 5.781(5) ${\AA}$. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.051 for the 573 observed reflections. The overall conformation of the base is quite different from those of the chloramphenicol congeners which are similar despite the presence of many rotatable single bonds. The propane chain in the base is bent with respect to the phenyl ring, while it is extended in the chloramphenicol congeners. There is no intramolecular hydrogen bond between the hydroxyl groups of the propanediol moiety. All of the molecules in the crystal lattice are connected by a three-dimensional hydrogen bonding network.

• The Pure and Applied Mathematics
• /
• v.29 no.4
• /
• pp.369-399
• /
• 2022

In the last few decades, a lot of generalizations of the Banach contraction principle have been introduced. In this paper, we present the notion of (𝜙, F)-contraction in generalized asymmetric metric spaces and we investigate the existence of fixed points of such mappings. We also provide some illustrative examples to show that our results improve many existing results.