• 대한수학회보
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• 제40권2호
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• pp.235-241
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• 2003

It is proved that the product of any two linearly independent meromorphic solutions of second order linear differential equations with coefficients of small lower growth must have infinite exponent of convergence of its zero-sequences, under some suitable conditions.

• Structural Engineering and Mechanics
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• 제85권4호
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• pp.545-562
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• 2023

In this work, superharmonic and subharmonic resonance of rotating stiffened FGM truncated conical shells exposed to harmonic excitation in a thermal environment is investigated. Utilizing classical shell theory considering Coriolis acceleration and the centrifugal force, the governing equations are extracted. Non-linear model is formulated employing the von Kármán non-linear relations. In this study, to model the stiffener effects the smeared stiffened technique is utilized. The non-linear partial differential equations are discretized into non-linear ordinary differential equations by applying Galerkin's method. The method of multiple scales is utilized to examine the non-linear superharmonic and subharmonic resonances behavior of the conical shells. In this regard, the effects of the rotating speed of the shell on the frequency response plot are investigated. Also, the effects of different semi-vertex angles, force amplitude, volume-fraction index, and temperature variations on the frequency-response graph are examined for different rotating speeds of the stiffened FGM truncated conical shells.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제24권1호
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• pp.45-51
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• 2017

In this paper, we propose an accelerating scheme of convergence of numerical solutions of fuzzy non-linear equations. Numerical experiments show that the new method has significant acceleration of convergence of solutions of fuzzy non-linear equation. Three-dimensional graphical representation of fuzzy solutions is also provided as a reference of visual convergence of the solution sequence.

• 한국산업융합학회 논문집
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• 제6권2호
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• pp.141-147
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• 2003

In this paper, the vibration characteristics of a linear stepping motor(LSM) are analyzed using the finite element method(FEM : Flux2D) and ACSL. A magnetic equivalent circuit is based on the structure of the LSM, and then the electric equivalent circuit of the LSM is derived by solving equations for the magnetic equivalent circuit. A normal force is calculated using FEM. And the vibration characteristics of the LSM are simulated by the ACSL with the voltage equations, the thrust equations, the normal force equations and the kinetic equations, and are measured by LASER experimental system.

• 호남수학학술지
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• 제24권1호
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• pp.67-73
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• 2002

In this paper we discuss on the existence of general solution of Partial Differential Equations $\frac{{\partial}w}{{\partial}\bar{z}}=F(z,\;w,\;\frac{{\partial}w}{{\partial}z})+G(z,\;w,\;\bar{w})$ in the Sololev Space $W_{1,p}(D)$, that is generalization of a first order Non-linear Elliptic System of Partial Differential Equations $\frac{{\partial}w}{{\partial}\bar{z}}=F(z,\;w,\;\frac{{\partial}w}{{\partial}z}).$

• Korean Journal of Mathematics
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• 제29권3호
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• pp.527-545
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• 2021

The aim of this article is to give a numerical method for solving Abel's general fuzzy linear integral equations with arbitrary kernel. The method is based on approximations of fractional integrals and Caputo derivatives. The convergence analysis for the proposed method is also given and the applicability of the proposed method is illustrated by solving some numerical examples. The results show the utility and the greater potential of the fractional calculus method to solve fuzzy integral equations.

• 한국항행학회논문지
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• 제13권1호
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• pp.62-67
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• 2009

VLSI 설계를 위한 회로 시뮬레이션, 영상처리, 구조 공학, 항공역학 등 공학 분야에서 대형 선형시스템 방정식의 해를 구하기 위해 고성능 컴퓨터에 대한 요구가 증가되고 있다. 이런 요구를 충족하기 위해 많은 다양한 병렬처리시스템이 제안되고 제작되고 있다. 선형시스템의 특성에 따라 그 해를 구하기 위한 적절한 알고리즘이 필요하다. 선형시스템 방정식의 해를 구하기 위해 여러 가지 직접법, 반복법이 사용되고 있다. 본 연구에서는 대형 스파스 행렬 형태를 가진 선형시스템 방정식의 해를 구하기 위해 지능적인 병렬반복법을 제안하고 효율성을 시뮬레이션에 의해 증명하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.202-206
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• 2001

The paper presents the dynamic stability of a vertical cantilevered pipe conveying fluid and having an intermediate translational linear spring. The translational linear spring can be located at an arbitrary position. Governing equations are derived by energy expressions, and numerical technique using Galerkin's method is applied to discretize the equations of small motion of the pipe. Effects of linear spring supports on the dynamic stability of a vertical cantilevered pipe conveying fluid are fully investigated for various locations and magnitudes of the translational linear spring.

• Korean Journal of Mathematics
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• 제29권1호
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• pp.65-73
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• 2021

In this paper, we investigate the growth properties of solutions of the non-homogeneous linear complex differential equation L(f) = b (z) f + c (z), where L(f) is a linear differential polynomial and b (z), c (z) are entire functions and give some of its applications on sharing value problems.

• 소음진동
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• 제6권5호
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• pp.567-574
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• 1996

This paper concerns an articulated space robot with flexible links. The equations of its motion are derived by means of the Lagrangian mechanics. Assuming that magnitude of elastic motions are relatively small, the perturbation approach is taken to separate the original equations of motion into linear and nonlinear equations. Th effect the desired payload motion, open loop control inputs are first determined based on the nonlinear equations. One the other hand, in order to reduce the positional errors during the maneuver, vibration suppression is actively done with a feedforward control for disturbance cancellation to some extent. Additionally, for performance robustness against residual disturbance, an LQ control modified to have a prescribed degree of stability is applied based on the linear equations. Measurement equations are formulated to be used for the maximum likelihood estimator to reconstruct states from the original robot equations of motion. Finally, numerical simulations show effectiveness of the proposed control design scheme.