• Computers and Concrete
• /
• v.5 no.4
• /
• pp.401-416
• /
• 2008

The paper presents a methodology to model three-dimensional reinforced concrete members by means of embedded discontinuity elements based on the Continuum Strong Discontinuous Approach (CSDA). Mixture theory concepts are used to model reinforced concrete as a 3D composite material constituted of concrete with long fibers (rebars) bundles oriented in different directions embedded in it. The effects of the rebars are modeled by phenomenological constitutive models devised to reproduce the axial non-linear behavior, as well as the bond-slip and dowel action. The paper presents the constitutive models assumed for the components and the compatibility conditions chosen to constitute the composite. Numerical analyses of existing experimental reinforced concrete members are presented, illustrating the applicability of the proposed methodology.

• Interaction and multiscale mechanics
• /
• v.1 no.3
• /
• pp.329-337
• /
• 2008

This paper presents the derivation of the generalized governing equations in theory of elasticity, their weak forms and the some applications in the numerical analysis of structural mechanics. Unlike the differential equations in classical elasticity theory, the generalized equations of the equilibrium and compatibility equations presented here take the form of integral equations, and the generalized equilibrium equations contain the classical differential equations and the boundary conditions in a single equation. By using appropriate test functions, the weak forms of these generalized governing equations can be established. It can be shown that various variational principles in structural analysis are merely the special cases of these weak forms of generalized governing equations in elasticity. The present weak forms of elasticity equations extend greatly the choices of the trial functions for approximate solutions in the numerical analysis of various engineering problems. Therefore, the weak forms of generalized governing equations in elasticity provide a powerful modeling tool in the computational structural mechanics.

• Proceedings of the KIEE Conference
• /
• 1994.11a
• /
• pp.9-11
• /
• 1994

FACTS concept is the control of power flow and increase of the loading on existing lines to the thermal limuts. This paper focuses on the ability of the thyristor controlled series compensator (TCSC) to stabilize the disturbed power systems. The result shows the potential benefit of the TCSC in addition to the role of controlling the steady state power flow. In order to show the effectiveness of controlled series capacitor, power system dynamic model is augmented and the effect of the SC into the power system dynamics is included. As a control algorithm, Linear Optimal Control theory is applied.

• Communications of the Korean Mathematical Society
• /
• v.27 no.1
• /
• pp.117-128
• /
• 2012

Using the concept of a g-monotone mapping we prove some common fixed point theorems for g-non-decreasing mappings which satisfy some generalized nonlinear contractions in partially ordered complete quasi b-metric spaces. The new theorems are generalizations of very recent fixed point theorems due to L. Ciric, N. Cakic, M. Rojovic, and J. S. Ume, [Monotone generalized nonlinear contractions in partailly ordered metric spaces, Fixed Point Theory Appl. (2008), article, ID-131294] and R. P. Agarwal, M. A. El-Gebeily, and D. O'Regan [Generalized contractions in partially ordered metric spaces, Appl. Anal. 87 (2008), 1-8].

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.7
• /
• pp.701-708
• /
• 2011

Natural convection heat transfers on inclined flat plates were measured for Grashof numbers of $8.06{\times}10^7$ and $3.45{\times}10^9$ by using a copper sulfate electroplating system. The inclinations of the plates were varied from upward-facing horizontal to downward-facing horizontal. Test results for the downward-facing plate agree well with the existing theory that the Nusselt number can be calculated by replacing gravitational acceleration, g with g $cos{\theta}$ in the heat transfer correlation for the vertical plate. The natural convection flows for the upward-facing plate follow two distinct flow regimes: boundary layer regime and flow separation regime. The copper plating pattern for the upward-facing plates clearly reveals the flow separation points.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.9
• /
• pp.770-775
• /
• 2002

We present the band lineups of G $e_{1-}$x S $n_{x}$ G $e_{1-}$y S $n_{y(001)}$ heterostructures for the new devices. The energy gap of the bulk G $e_{1-}$x S $n_{x}$ alloy is calculated by taking into account the Vegard's law. The change of the energy gap due to the strain is understood in terms of the deformation Potential theory The valence band offset is obtained from the average bond energy model, where the changes of the band offset due to alloy compositions and strain are included. It is found that Ge/G $e_{1-}$y S $n_{y(001)}$ heterostructure has a staggered lineup type for 0$\leq$0.06 and a straddling one for 0.06$\leq$0.26. Meanwhile, Ge/G $e_{l-y}$ S $n_{y(001)}$ heterostructure has a staggered lineup type for 0$\leq$0.19 and a broken-gap one for 0.19$\leq$0.26. As a result, the various type of the G $e_{1-}$x S $n_{x}$ G $e_{1-}$y S $n_{y(001)}$ heterostructure can be applied for the useful device.evice.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.222-224
• /
• 1996

This paper treats the stream phenomena of high frequency current on the solid-loop coil of which consists the hollow conductor. The governing equation is derived from electromagnetic field theory and the characteristics are analyzed by FEM with 2-D and 3-D. The results may be available data on designing the optimum shape of the coil for the improved pinch effect.

• Structural Engineering and Mechanics
• /
• v.13 no.5
• /
• pp.533-542
• /
• 2002

This paper considers the buckling and post-buckling behavior of empty metal storage tanks under wind load. The structures of such tanks may be idealized as cantilever cylindrical shells, and the structural response is investigated using a computational model. The modeling employs a doubly curved finite element based on a theory by Simo and coworkers, which is capable of handling large displacements and plasticity. Buckling results for tanks with four different geometric relations are presented to consider the influence of the ratios between the radius and the height of the shell (R/L), and between the radius and the thickness (R/t). The studies aim to clarify the differences in the shells regarding their imperfection-sensitivity. The results show that thin-walled short tanks, with R/L = 3, display high imperfection sensitivity, while tanks with R/L = 0.5 are almost insensitive to imperfections. Changes in the total potential energy of tanks that would buckle under the same high wind pressures are also considered.

• Earthquakes and Structures
• /
• v.27 no.2
• /
• pp.155-164
• /
• 2024

Studying the propagation characteristics of waves in circular plates has important engineering value. In this paper, graphene sheet reinforced foam (GPLRMF) circular plates are taken as the research object, and the propagation characteristics of shear and bending waves in the structure are analyzed. In the process of research, we assume that the material properties are closely related to temperature, and use the first-order shear deformation theory (FSDT) to establish the dynamic model of GPLRMF circular plates. Considering the simply supported boundary conditions, the relationship between phase velocity/group velocity and wave number was obtained through Laplace transform. Subsequently, the influence of material and geometric parameters on wave propagation characteristics was analyzed, and the results showed that the porosity coefficient and temperature had a significant impact on the characteristics of wave propagation in circular plates.

• Asia pacific journal of information systems
• /
• v.25 no.3
• /
• pp.500-518
• /
• 2015

The present research aims to identify the relationship between trust and distrust in an online business environment. To clarify the concepts, cognitive-affective personality system theory was introduced, through which five types of psychological units were proposed. In developing the research model based on the theory, technical effectiveness of the system and content truthfulness of the website were selected as two key stimuli for the coding process of online users. Trust and distrust were selected as mediating factors that generate consequent behaviors. Finally, purchase intention served as a final dependent variable. Assuming that trust and distrust emerge in psychologically different stages, this study hypothesized the mutual causal relationship between trust and distrust, indicating that the relationship will be determined by their contextual emphasis on each dimension. To validate, a survey was conducted with 307 online shopping mall users. Results show that stimuli were more significantly associated with trust. Trust is therefore a more cognitive construct than distrust, and the path from trust to distrust is stronger than that from distrust to trust. This finding implies that the cognitive aspect of trust is stronger than that of distrust. Distrust is rather more affectively emerging than trust.