• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.04a
• /
• pp.1-8
• /
• 2004

For the linearized differential algebraic equation of the nonlinear constrained system, exact initial values of the acceleration are needed to solve itself. It may be very troublesome to perform the inverse operation for obtaining the incremental quantities since the mass matrix contains the zero element in the diagonal. This fact makes the mass matrix impossible to be positive definite. To overcome this singularity phenomenon the mass matrix needs to be modified to allow the feasible application of predictor and corrector in the iterative computation. In this paper the proposed numerical algorithm based on the modified mass matrix combines the conventional implicit algorithm, Newton-Raphson method and Newmark method. The numerical example presents reliabilities for the proposed algorithm via comparisons of the 4th order Runge-kutta method. The proposed algorithm seems to be satisfactory even though the acceleration, Lagrange multiplier, and energy show unstable behaviour. Correspondingly, it provides one important clue to another algorithm for the enhancement of the numerical results.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.295-300
• /
• 2005

The freeplay, one of the concentrated structural nonlinearities, is inevitable for control surfaces of a real air vehicle due to normal wear of components and manufacturing mismatches. Also aerodynamic nonlinearities caused by a shock wave occur in transonic region. In practice, these nonlinearities induce the limit cycle oscillation (LCO) and decrease the transonic flutter speed. In this study, the fictitious mass method is used to apply a modal approach to nonlinear structural models due to freeplay. The transonic small-disturbance (TSD) equation is used to calculate unsteady aerodynamic forces in transonic region. Nonlinear aeroelastic time responses are predicted by the coupled time integration method (CTIM). This method was also applied to a 3D all-movable control wing to investigate its nonlinear aeroelastic responses. The angle of attack effect on the LCO characteristics has been found to be closely related with the initial pitching moment.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.109-114
• /
• 2009

As one of the promising model on the multiphase fluid mixtures, the Lattice-Boltzmann Method(LBM) is being developed to simulate flows containing two immisible components which are different mass values. The equilibrium function in the LBM can have a nonideal gas model for the equation of state and use the interfacial energy for the phase separation effect. An example on the phase separation has been carried out through the time evolution. The LBM based on the statistic mechanics is appropriate to solve very complicated flow problems and this model gives comparative merits rather than the continuum mechanics model.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.1636-1640
• /
• 2006

SMAC method, one of the computational fluid dynamics techniques, is modified from the original MAC method for the time-dependent variation of flow analysis. The Navier-Stokes equations for incompressible time-dependent viscous flow are applied, and also marker particles that present the visualization of flow analysis are used. In this study SMAC technique is used to analyze the flow behavior in the water-filling of virtual channel. Then by changes of diameter of two ingates, the change of velocity and discharge when two ingates are filled the water to virtual channel are simulated. As a result, water-filling flow pattern in the virtual channel is simulated very well. Therefore, this numerical simulation will also be applied for the design of structures as open flume and porous breakwater.

• Journal of Agricultural Extension & Community Development
• /
• v.15 no.3
• /
• pp.433-460
• /
• 2008

The objectives of this study were to figure out the relationships of factors, e-quality, interactivity, trust and switching barrier, to affect the online customers loyalty. Moreover, e-quality was considered because of the problem of ssability originated from the environment that a lot of information and products are given at online business. This study employs a survey method to empirically test the proposed research model. A survey questionnaire was developed and 100 responses were collected. The data were analyzed using PLS method, a structural equation modeling method. The results of the study indicate that e-quality, interactivity, and trust influence switching barrier and that the switching barrier affects virtual relationship, which has an positive effect on loyalty. This study provides valuable theoretical and practical perspectives that e-quality is the most influential factor on virtual relationship and that, of the three factors of switching barrier, the virtual relationship is the most effective one to prevent customers online from changing their main online shop for products.

• Korean Journal of Mathematics
• /
• v.17 no.4
• /
• pp.419-428
• /
• 2009

We show the existence of at least one nontrivial solution of the homogeneous mixed type nonlinear elliptic problem. Here mixed type nonlinearity means that the nonlinear part contain the jumping nonlinearity and the critical growth nonlinearity. We first investigate the sub-level sets of the corresponding functional in the Soboles space and the linking inequalities of the functional on the sub-level sets. We next investigate that the functional I satisfies the mountain pass geometry in the critical point theory. We obtain the result by the mountain pass method, the critical point theory and variational method.

• Journal of applied mathematics & informatics
• /
• v.35 no.5_6
• /
• pp.439-447
• /
• 2017

This paper investigates the inverse problem of determining an unknown heat radiative coefficient, which is only time-dependent. This is an ill-posed problem, that is, small errors in data may cause huge deviations in determining solution. In this paper, the existence and uniqueness of the problem is established by the second Volterra integral equation theory, and the method of trace-type functional formulation combined with finite difference scheme is studied. One typical numerical example using the proposed method is illustrated and discussed.

• Tribology and Lubricants
• /
• v.3 no.1
• /
• pp.18-25
• /
• 1987

The influence of one sided striated surface roughness on load carrying capacity of a slider bearing is analyzed for very low clearance films. A Reynolds equation appropriate for slider bearing is derived and analyzed by the method of finite difference method. For a slider bearing with several simple roughness form, the pressure, load capacity and other parameters can be revealed and also this results can be stored in sequential data file. After all, their distribution can be displayed easily by using the CADG(Computer Aided Design and Graphics) program. Also exact solutions with this nemerical method are compared with those of the theory attributed to Tonder and White. The results reported here should find application in the computer peripherals where computer aided design and graphic package is needed.

• Coupled systems mechanics
• /
• v.1 no.4
• /
• pp.325-343
• /
• 2012

We present different numerical methods for solving the shallow shelf equations with basal drag (SSAB). An alternative approach of splitting the SSAB equation into a Laplacian and diagonal shift operator is discussed with respect to the underlying eigenvalue problem. First, we solve the equations using standard methods. Then, the coupled equations are decomposed into operators for membranes stresses, basal shear stress and driving stress. Applying reasonable parameter values, we demonstrate that the operator of the membrane stresses is much stiffer than the operator of the basal shear stress. Here, we could apply a new splitting method, which alternates between the iteration on the membrane-stress operator and the basal-shear operator, with a more frequent iteration on the operator of the membrane stresses. We show that this splitting accelerates and stabilize the computational performance of the numerical method, although an appropriate choice of the standard method used to solve for all operators in one step speeds up the scheme as well.

• Bulletin of the Korean Mathematical Society
• /
• v.50 no.6
• /
• pp.2035-2051
• /
• 2013

In this paper, we study numerical schemes for solving multi-dimensional option pricing problem. We compare the direct solving method and the Operator Splitting Method(OSM) by using finite difference approximations. By varying parameters of the Black-Scholes equations for the maximum on the call option problem, we observed that there is no significant difference between the two methods on the convergence criterion except a huge difference in computation cost. Therefore, the two methods are compatible in practice and one can improve the time efficiency by combining the OSM with parallel computation technique. We show numerical examples including the Equity-Linked Security(ELS) pricing based on either two assets or three assets by using the OSM with the Monte-Carlo Simulation as the benchmark.