• Journal of the Korean Mathematical Society
• /
• v.42 no.2
• /
• pp.191-202
• /
• 2005

A condition on forcing term insuring the multiplicity of Dirichlet-periodic solutions of nonlinear dissipative hyperbolic equations is discussed. The nonlinear term is assumed to have coercive growth.

• Journal of the Chungcheong Mathematical Society
• /
• v.21 no.3
• /
• pp.339-345
• /
• 2008

We prove the existence of the positive solution for the nonlinear system of suspension bridge equations with Dirichlet boundary condition and periodic condition $$\{u_{tt}+u_{xxxx}+av^+=1+{\epsilon}_1h_1(x,t)\text{ in }(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,\\v_{tt}+v_{xxxx}+bu^+=1+{\epsilon}_2h_2(x,t)\text{ in }(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,$$ where $u^+={\max}\{u,0\},\;{\epsilon}_1,\;{\epsilon}_2$ are small numbers and $h_1(x,t)$, $h_2(x,t)$ are bounded, ${\pi}$-periodic in t and even in x and t and ${\parallel}h_1{\parallel}={\parallel}h_2{\parallel}=1$.

• Journal of applied mathematics & informatics
• /
• v.26 no.1_2
• /
• pp.29-44
• /
• 2008

By employing the continuation theorem of coincidence degree theory, we derive a sufficient condition for the existence and attractricity of a positive periodic solution for a generalized predator-prey model with diffussion feedback controls.

• Journal of applied mathematics & informatics
• /
• v.29 no.1_2
• /
• pp.39-48
• /
• 2011

Some existence theorems are obtained for periodic solutions of nonautonomous second-order differential systems with (q, p)-Laplacian by the minimax methods in critical point theory.

• Korean Journal of Mathematics
• /
• v.17 no.2
• /
• pp.219-231
• /
• 2009

We show the existence of at least four solutions for the perturbed parabolic equation with Dirichlet boundary condition and periodic condition when the nonlinear part cross two eigenvalues of the eigenvalue problem of the Laplace operator with boundary condition. We obtain this result by using the Leray-Schauder degree theory, the finite dimensional reduction method and the geometry of the mapping. The main point is that we restrict ourselves to the real Hilbert space instead of the complex space.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.24-26
• /
• 1994

This paper deals with the 3 dimensional finite element analysis using the periodic boundary condition in case analyzing model has a periodic structure. Using the periodic boundary condition we can reduce computer's memories and computation tine. because only the one period of the model is analyzed. To verify the usefulness of the proposed algorithm, can stack type PM step motor which used in FDD head driver is choosen and analyzed.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2477-2482
• /
• 2008

Effect of computational domain size in simulating of periodic obstacle flow has been investigated for the flow past tube banks. Reynolds number, defined by freestream velocity (U) and cylinder diameter (d), was fixed as 200, and center-to-center distance (P) as 1.5d. In-line square array was considered. Drag coefficient, lift coefficient and Strouhal number were calculated depending on domain size. Circular cylinders were implemented on a Cartesian grid system by using an immersed boundary method. Boundary condition is periodic in both streamwise and lateral directions. Previous studies in literature often use a square domain with a side length of P, which contains only one cylinder. However, this study reveals that size is improper. Especially, RMS values of flow-induced forces are most sensitive to the domain size.

• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.543-549
• /
• 2011

In this paper, diagonal implicit harmonic balance method is applied to analyze helicopter rotor blade flow. Periodic boundary condition for Fourier coefficients is also applied in hover and forward flight condition. It is available enough to simulate the forward flight problem with only one rotor blade using the periodic boundary condition in frequency domain. In order to demonstrate present method Carodonna & Tung's rotor blades are used and the results are compared to time-accurate method and experimental data.

• Journal of the Korean Mathematical Society
• /
• v.49 no.2
• /
• pp.315-324
• /
• 2012

We consider the global existence of strong solutions of the 3D incompressible Navier-Stokes equations in a long periodic domain. We show by a simple argument that a strong solution exists globally in time when the initial velocity in $H^1$ and the forcing function in $L^p$([0; T);$L^2$), T > 0, $2{\leq}p{\leq}+\infty$ satisfy a certain condition. This condition common appears for the global existence in thin non-periodic domains. Larger and larger initial data and forcing functions satisfy this condition as the thickness of the domain $\epsilon$ tends to zero.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1326-1329
• /
• 1997

In designing the controller by changing the weighting matrix for the pirpose of satisfying constraints, the physical meaning of weighting matrix may disapperar and the system may not yield best performance because operation condition such as periodic disturbance was not considered. In this paper, the weighting matrix is fixed and controller is designed to minimize the new performance index to reduce the effects of periodic-type disturbances. This method is applied to design the satellite controller to verify the effetiveness.