• Structural Engineering and Mechanics
• /
• 제42권6호
• /
• pp.849-866
• /
• 2012

Single span historic bridges often contain non-prismatic members identified with a varying depth along their span lengths. Commonly, the symmetric parabolic height variations having the constant haunch length ratio of 0.5 have been selected to lower the stresses at the high bending moment points and to maintain the deflections within the acceptable limits. Due to their non-prismatic geometrical configuration, their assessment, particularly the computation of fixed-end horizontal forces (FEFs) and fixed-end moments (FEMs) becomes a complex problem. Therefore, this study aimed to investigate the behavior of non-prismatic beams with symmetrical parabolic haunches (NBSPH) having the constant haunch length ratio of 0.5 using finite element analyses (FEA). FEFs and FEMs due to vertical loadings as well as the stiffness coefficients and the carry-over factors were computed through a comprehensive parametric study using FEA. It was demonstrated that the conventional methods using frame elements can lead to significant errors, and the deviations can reach to unacceptable levels for these types of structures. Despite the robustness of FEA, the generation of FEFs and FEMs using the nodal outputs of the detailed finite element mesh still remains an intricate task. Therefore, this study advances to propose effective formulas and dimensionless estimation coefficients to predict the FEFs, FEMs, stiffness coefficients and carry-over factors with reasonable accuracy for the analysis and re-evaluation of the NBSPH. Using the proposed approach, the fixed-end reactions due to vertical loads, and also the stiffness coefficients and the carry-over factors of the NBSPH can be determined without necessitating the detailed FEA.

• 반도체디스플레이기술학회지
• /
• 제12권2호
• /
• pp.85-91
• /
• 2013

In this paper, the parabolic antenna aims to the precise location of a moving ship or car that can be designed system using the gyro sensor. The parabolic antenna has controlled by stepping motor that is a lot of noise and slow response of speed. It has solved the problem which is noise and slow response using the BLDC motor. Also, in order to suppress the noise two-axis control and a separate encoder to the six degrees of freedom motion system was implemented in a precise location. Generally, the gyro sensor is not required to system that doesn't move the six degrees of freedom motion system. But the system will be applied to the moving such as ships or cars. Finally, we presented the position control algorithm at the sometimes controlled both gyro sensor and BLDC motor. This system was tracking that the location of the antenna to the desired angle and errors almost didn't happen when the system was moved 6 degrees of freedom.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제4권2호
• /
• pp.41-57
• /
• 2000

In this paper, we consider first order generalized difference scheme for the two-point boundary value problem and one-dimensional second order parabolic type problem. The optimal error estimates in $L_p$ and $W^{1,p}$ ($2{\leq}p{\leq}{\infty}$) as well as some superconvergence estimates in $W^{1,p}$ ($2{\leq}p{\leq}{\infty}$) are obtained. The main results in this paper perfect the theory of GDM.

• 대한수학회논문집
• /
• 제17권4호
• /
• pp.565-576
• /
• 2002

본 개관에서는 Ambrosetti-Prodi형의 해의 다중존재성에 관하여 살펴볼 것이다.

• Kyungpook Mathematical Journal
• /
• 제62권4호
• /
• pp.615-640
• /
• 2022

In this paper, we investigate a time-dependent double obstacle problem associated with the model of European call option pricing with transaction costs. We prove the existence and uniqueness of a W^2,1_p,loc solution to the problem. We then characterize the behavior of the free boundaries in terms of continuity and values of limit points.

• 한국농공학회논문집
• /
• 제58권1호
• /
• pp.81-90
• /
• 2016

The Agricultural Systems Application Platform (ASAP) provides bottom-up modelling and simulation environment for agricultural engineer. The purpose of this study is to expand usability of the ASAP to the second order partial differential equations: elliptic equations, parabolic equations, and hyperbolic equations. The ASAP is a general-purpose simulation tool which express natural phenomenon with capsulized independent components to simplify implementation and maintenance. To use the ASAP in continuous problems, it is necessary to solve partial differential equations. This study shows usage of the ASAP in elliptic problem, parabolic problem, and hyperbolic problem, and solves of static heat problem, heat transfer problem, and wave problem as examples. The example problems are solved with the ASAP and Finite Difference method (FDM) for verification. The ASAP shows identical results to FDM. These applications are useful to simulate the engineering problem including equilibrium, diffusion and wave problem.

• Korean Journal of Mathematics
• /
• 제19권2호
• /
• pp.111-127
• /
• 2011

We prove the uniqueness solvability of the Tricomi problem for the elliptic - hyperbolical equation of the second type by using a new representation of the solution in the generalized class R.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제3권1호
• /
• pp.1-15
• /
• 1999

Gradient recovery techniques for the second order elliptic boundary value problem are well known. In particular, the Midpoint and the Vertex Recovery Operator have been studied by various authors and under suitable assumptions on the regularity of the unknown solution superconvergence property of these recovered gradients have been proved. In this paper we extend these results to the recovered gradient of the finite element approximation to a model initial-boundary value problem, and go on to prove superconvergence result for this recovered gradient in a discrete (in time) error norm.

• Journal of applied mathematics & informatics
• /
• 제41권1호
• /
• pp.155-165
• /
• 2023

We consider circular Rayleigh problem of hydrodynamic stability which deals with linear stability of axial flows of an incompressible iniviscid homogeneous fluid to axisymmetric disturbances. For this problem, we obtained two parabolic instability regions which intersect with Batchelor and Gill semi-circle under some condition. This has been illustrated with examples. Also, we derived upper bound for the amplification factor.

• 한국음향학회지
• /
• 제33권6호
• /
• pp.383-391
• /
• 2014

수중의 음향 신호를 탐지하기 위하여 다양한 배열 형태를 가지는 소나가 개발되어 왔으며, 그 중 하나로 견인선배열 소나가 널리 사용된다. 견인 선배열 소나는 매우 긴 형태의 배열을 사용하므로, 회전에 의한 형상 왜곡에 의해 성능이 저하되는 단점이 있다. 이를 해결하기 위하여 회전하는 견인 선배열 소나에 대한 포물선 형태의 형상 모델을 이용하는 기법이 고안되었다. 본 논문에서는 포물선 모델을 이용하여 간섭 신호를 제거하는 적응 빔 형성기 설계 기법을 제안한다. 고안된 빔형성기 시스템은 일반화된 부엽 제거기 구조와 자가 조율 시스템에 기반을 두어 개발되었다.