• Journal of Mechanical Science and Technology
• /
• v.18 no.9
• /
• pp.1529-1536
• /
• 2004

A structure is broken down into a number of substructures by means of the finite element method and the substructures are synthesized for the complete structure. The divided substructures take two types: fixed-free and free-free elements. The flexibility and stiffness matrices of the free-free elements are the Moore-Penrose inverse of each other. Thus, it is not easy to determine the equilibrium equations of the complete structure composed of two mixed types of substructures. This study provides the general form of equilibrium equation of the entire structure through the process of assembling the equilibrium equations of substructures with end conditions of mixed types. Applications demonstrate that the proposed method is effective in the structural analysis of geometrically complicated structures.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.2
• /
• pp.201-210
• /
• 2000

The large deflection of plate is analyzed by co-rotational formulations using small local displacements and rotating unit vectors on the nodal points. The rotational degrees of the freedom are represent ed by the unit vectors1 In the nodal points, and the equilibrium equations are formulated by using small deflection theories of the plates by assuming that the directions of the unit vectors of the nodal points are known apriori. The translational degrees of freedom are independently solved from the rotational degrees of freedom in the equilibrium equations, and the correct directions of the unit vectors are computed by the iterative scheme by imposing the moment equilibrium constraint. The equilibrium equations and the associated solution procedure are explained, and the verification problems are solved.

• Proceedings of the KIEE Conference
• /
• 1999.11c
• /
• pp.815-817
• /
• 1999

In this paper, we developed a fuzzy identification system to evaluate sensation of equilibrium objectively and quantitatively. By using caloric test. we estimated ECG(electro-cardiogram) and EOG(electro-oculogram), which were biomedical signals related to sensation of equilibrium, and used them as inputs of fuzzy identification system input. Fuzzy identification system analyzed the relationality between biomedical signals and sensation of equilibrium automatically, and evaluated it taking the co-relation between these signals into consideration.

• Structural Engineering and Mechanics
• /
• v.5 no.5
• /
• pp.577-586
• /
• 1997

In nonlinear finite element stability analysis of structures, the foremost necessary procedure is the computation to precisely locate a singular equilibrium point, at which the instability occurs. The present study describes global and local procedures for the computation of stability points including bifurcation points and limit points. The starting point, at which the procedure will be initiated, may be close to or arbitrarily far away from the target point. It may also be an equilibrium point or non-equilibrium point. Apart from the usual equilibrium path, bypass and homotopy path are proposed as the global path to the stability point. A local iterative method is necessary, when it is inspected that the computed path point is sufficiently close to the stability point.

• 한국전산유체공학회:학술대회논문집
• /
• 1995.10a
• /
• pp.203-212
• /
• 1995

In this paper the upwind flux difference splitting Navier-Stokes method has been applied to study the perfect gas and the equilibrium chemically reacting hypersonic flow over an axisymmetric sphere-cone($5^{\circ}$) geometry. The effective gamma($\bar{r}$), enthalpy to internal energy ratio was used to couple chemistry with the fluid mechanics for equilibrium chemically reacting air. The test case condition was at altitude(30Km) and Mach number(15). The equilibrium shock thickness over the blunt body region was much thinner than that of perfect gas shock. The pressure difference between perfect gas and equilibrium gas was about $3\sim5$ percent. The skin friction coefficient and heat transfer coefficient were also calculated.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.112-117
• /
• 2000

A numerical study on natural convection in a vertical square cavity filled with a porous medium is carried out with Brinkman-Forchheimer-extended Darcy flow model, and the validity of local thermodynamic equilibrium assumption is studied. The local thermodynamic equilibrium refers to the state in which a single temperature can be used to describe a heat transfer process in a multiphase system. With this assumption, the analysis is greatly simplified because only one equation is needed to describe the heat transfer process. But prior to using this assumption, it is necessary to know in what conditions the assumption can be used. The numerical results of this study reveal that large temperature difference between fluid phase and solid phase exists near wall region, paticularily when the convection becomes dominant over conduction. And the influence of flow parameters such as fluid Rayleigh number, fluid Prandtl number, dimensionless particle diameter and conductivity ratio are investigated.

• Journal of Institute of Control, Robotics and Systems
• /
• v.10 no.6
• /
• pp.510-518
• /
• 2004

The PID trajectory tracking controller for robotic systems shows performance limitation imposed by inverse dynamics according to desired trajectory. Since the equilibrium point can not be defined for the control system involving performance limitation, we define newly the quasi-equilibrium region as an alternative for equilibrium point. This analysis result of performance limitation can guide us the auto-tuning method for PID controller. Also, the quasi-equilibrium region is used as the target performance of auto-tuning PID trajectory tracking controller. The auto-tuning law is derived from the direct adaptive control scheme, based on the extended disturbance input-to-state stability and the characteristics of performance limitation. Finally, experimental results show that the target performance can be achieved by the proposed automatic tuning method.

• Journal of Korean Institute of Industrial Engineers
• /
• v.28 no.4
• /
• pp.379-389
• /
• 2002

In this paper, we study the competition between two kinds of suppliers, a bricks and mortars(B&M) and a clicks and mortars(C&M). Using the circular spatial market model, we derive and analyze the Nash and Stackelberg equilibria as a function of offline market share and efficiency of online channel of the C&M supplier. The result can be summarized as follows: (1) Stackelberg equilibrium is always superior to the Nash equilibrium, (2) Under certain conditions, the price of online channel can be higher than that of offline channel, (3) It is impossible for the C&M supplier to encroach on all of the B&M supplier's market, (4) In some cases, the C&M supplier has incentive to lower the efficiency of its online channel for more profit.

• Journal of Korean Institute of Industrial Engineers
• /
• v.27 no.2
• /
• pp.181-189
• /
• 2001

The proliferation of the Internet and related technologies and applications has led to a new form of market place known as the electronic store. In this paper, we study competition between two shopping channels, an electronic store and traditional retailers. Based on the circular spatial market model, we derive the Nash and Stackelberg equilibria as a function of the efficiency of the electronic store. The result shows that the Stackelberg equilibrium is always superior to the Nash equilibrium for both channels. It is also shown that, in some cases, the electronic store has incentive to decrease its efficiency to gain more profit.

• Nuclear Engineering and Technology
• /
• v.43 no.6
• /
• pp.547-556
• /
• 2011

Two computational methods for determining equilibrium states for the Mark-IV electrorefiner (ER) have been assessed to improve the current computational electrorefiner model developed at University of Idaho. Both methods were validated against measured data to better understand their effects on the calculation of the equilibrium compositions in the ER. In addition, a sensitivity study was performed on the effect of specific unknown activity coefficients-including sodium in molten cadmium, zirconium in molten cadmium, and sodium chloride in molten LiCl-KCl. Both computational methods produced identical results, which stayed within the 95% confidence interval of the experimental data. Furthermore, sensitivity to unavailable activity coefficients was found to be low (a change in concentration of less than 3 ppm).