• Architectural research
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• v.8 no.2
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• pp.37-42
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• 2006

Starting from the quadratic optimal control algorithm, this study obtains the relation of the performance index for constrained systems and Gauss's principle. And minimizing a function of the variation in kinetic energy at constrained and unconstrained states with respect to the velocity variation, the dynamic equation is derived and it is shown that the result compares with the generalized inverse method proposed by Udwadia and Kalaba. It is investigated that the responses of a 10-story building are constrained by the installation of a two-bar structure as an application to utilize the derived equations. The structural responses are affected by various factors like the length of each bar, damping, stiffness of the bar structure, and the junction positions of two structures. Under an assumption that the bars have the same mass density, this study determines the junction positions to minimize the total dynamic responses of the structure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.352-360
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• 1997

An inverse dynamic procedure for spatial multibody systems containing flexible bodies is developed in the relative joint coordinate space. Constraint acceleration equations are derived in terms of relative coordinates using the velocity transformation technique. An inverse velocity transformation operator, which transforms the Cartesian velocities to the relative velocities, is derived systematically corresponding to the types of kinematic joints connecting the bodies and the system reference matrix. Using the resulting matrix, the joint reaction forces and moments are analyzed in the Cartesian coordinate space. The formulation is illustrated by means of two numerical examples.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.80-89
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• 2014

A stochastic optimal power flow (S-OPF) model considering uncertainties of load and wind power is developed based on chance constrained programming (CCP). The difficulties in solving the model are the nonlinearity and probabilistic constraints. In this paper, a limit relaxation approach and an iterative learning control (ILC) method are implemented to solve the S-OPF model indirectly. The limit relaxation approach narrows the solution space by introducing regulatory factors, according to the relationship between the constraint equations and the optimization variables. The regulatory factors are designed by ILC method to ensure the optimality of final solution under a predefined confidence level. The optimization algorithm for S-OPF is completed based on the combination of limit relaxation and ILC and tested on the IEEE 14-bus system.

• Transactions of Materials Processing
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• v.4 no.3
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• pp.222-232
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• 1995

The planar anisotripic FEM analysis for predicting earing profiles and draw-in amounts in the deep-drawing process is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-based unit vector and normal contact pressure. The consistent full set of governing relations, which is comprising euilbrium and geometric constraint equations, is appropriately linearized. Barlat's strain-rate potential is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and potential parameters. The linear triangular membrane elements are used for depicting the formed sheet. In the numerical simulations of deep drawing processes of a flat-top cylindrical cup for 2090-T3 aluminum alloy sheet show good agreement with experiments, although some discrepancies were observed in the directional trend of cup height and thickness strains.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.819-823
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• 2003

The differential equations governing the shape of displacement for the shallow parabolic arch subjected to multiple dynamic point step loads were derived and solved numerically The Runge-Kutta method was used to perform the time integrations. Hinged-hinged end constraint was considered. Based on the Budiansky-Roth criterion, the dynamic critical point step loads were calculated and the dynamic stability regions for such loads were determined by using the data of critical loads obtained in this study.

• Journal of KSNVE
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• v.2 no.2
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• pp.125-134
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• 1992

In this study, ti identify the dynamic characteristics of automobile steering system which consists of many components and joints, each component combined structure was analyzed using commercial structural package, ANSYS. And, the finite element method for each component and modeling method of several joints universal joint, bolt joint, bearing, etc. were studied. On the other hand, the experimental modal analysis was performed to compare with the results of the finite element analysis and joint modeling. The result shows very close agreement between two analysis. Also, it was found that the steeing column used in this experiment does not effect the low frequency mode of entire system. In addition, we found that constraint equations need to be considered in modeling universal joint. Since the stiffness effect of Urethane around wheel could be ignored, it can be modeled only with mass effect. In the end, it was found that dynamic characteristics of the entire steerintg system depends mainly upon the wheel characteristics.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.24 no.2
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• pp.121-141
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• 2020

Nanofluids is the fluids mixed with nanoscale particles and the mixed nano size materials affect heat transport. Researchers in this field has been focused on modeling and numerical computation by engineers In this paper, we analyze stability constraint of the dominant equations and check validate of the condition for most kinds of materials. So we mathematically analyze stability of the system. Also we apply Gauge-Uzawa algorithm to solve the system and prove stability of the method.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.130-134
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• 2017

Organic aerosols dispersed in the atmosphere likely undergo phase separation. Such internally mixed particles are often described as comprising an organic phase and an aqueous phase separately. We studied the morphology of two liquid separated aerosols in the sub-microscale by using a simple thermodynamic model with Russian doll geometry. The morphology of particles can be easily predicted from the simple criteria on the surface tension and two algebraic equations (the volume constraint and Young equation). This result may give the potential explanation about the complex morphology of the organic airborne particles.

• 전기의세계
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• v.24 no.5
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• pp.72-80
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• 1975

In this paper an application of the Monte Carlo method to optimum circuit design is discussed. T. Tsuda and T. Kiyono's algorithm based on the Monte Carlo method for solving multiple simul-taneous nonlinear equations is generalized to apply it to finding solutions of the constrained nonlinear optimization problem. The generalized algorithm derived here is directly applied to economical circuit design. In the cirsuit design, the object function is a cost function which is related to the cost of each circuit component. The constraint is the variance of the total system expressed by the variances of each circuit component. The design is to be determined so that the circuit has specified drift reliability with minimum cost. A practical example of economical circuit design and a general nonlinear function minimization is presented with food results.

• Wind and Structures
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• v.5 no.1
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• pp.15-24
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• 2002

This paper reports the numerical calculations of uniform turbulent shear flow around a square cylinder. The predictions are obtained by solving the two-dimensional unsteady Navier-Stokes equations in a finite volume technique. The turbulent fluctuations are simulated by the standard $k-{\varepsilon}$ model and one of its variant which takes care of the realizability constraint in order to suppress the excessive generation of turbulence in a stagnation condition. It has been found that the Strouhal number and the mean drag coefficient are almost unaffected by the shear parameter but the mean lift coefficient is increased. The present predictions are compared with available experimental data.