• Coupled systems mechanics
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• 제7권6호
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• pp.691-705
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• 2018

In this paper, nonlinear displacements of laminated composite beams are investigated under non-uniform temperature rising with temperature dependent physical properties. Total Lagrangian approach is used in conjunction with the Timoshenko beam theory for nonlinear kinematic model. Material properties of the laminated composite beam are temperature dependent. In the solution of the nonlinear problem, incremental displacement-based finite element method is used with Newton-Raphson iteration method. The distinctive feature of this study is nonlinear thermal analysis of Timoshenko Laminated beams full geometric non-linearity and by using finite element method. In this study, the differences between temperature dependent and independent physical properties are investigated for laminated composite beams for nonlinear case. Effects of fiber orientation angles, the stacking sequence of laminates and temperature on the nonlinear displacements are examined and discussed in detail.

• 한국전자파학회논문지
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• 제15권7호
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• pp.685-691
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• 2004

본 논문에서는 Multi-code CDMA(code division multiple access) 시스템에서 발생하는 높은 PAPR(Peak to average power ratio)을 저감하고, 신호가 HPA에서 비선형 왜곡을 감소시키기 위한 방법으로, SLM(Selected Mapping) 및 PTS(Partial Transmit Sequence) 기법과 함께 전치왜곡 기법의 혼합 기법을 제안한다. 제안된 기법에서 SLM 및 PTS 방법을 위해 사용된 위상 회전 정보는 별도의 채널을 통해 전송되고, 이러한 위상 회전 정보의 채널 통과에 따른 에러율은 시스템의 성능에 큰 영향을 미친다. 따라서 본 논문에서는 위상 회전 정보의 에러율을 고려한 이론적인 BER 수식을 제시하며, 이는 시뮬레이션을 통해 나타난 시스템의 BER 성능과 거의 같게 나타난다. 결국 PTS 및 SLM 방법을 전치왜곡기와 병행한 제안된 혼합 기법은 신호의 PAPR을 줄이고, HPA의 비선형 특성을 보상함으로써 시스템의 BER 성능을 향상시킨다.

• Structural Engineering and Mechanics
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• 제72권4호
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• pp.433-441
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• 2019

In this paper, geometrically nonlinear static analysis of laminated composite beams is investigated under hygrothermal effect. In the solution of problem, the finite element method is used within the first shear beam theory. Total Lagrangian approach is used nonlinear kinematic model. The geometrically nonlinear formulations are developed for the laminated beams with hygro-thermal effects. In the nonlinear solution of the problem, the Newton-Raphson method is used with incremental displacement. In order to verify of obtained formulations, a comparison study is performed. The effects of the fiber orientation angles, the stacking sequence of laminates, temperature rising and moisture changes on the nonlinear static displacements and configurations of the composite laminated beam are investigated in the numerical results.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5979-5986
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• 2013

본 연구에서는 복합재료 적층 쉘 구조의 기하학적 비선형 동적 거동을 상세 분석하였다. Sanders의 1차 전단 변형 쉘이론 및 비선형 방정식을 기반하여, 비선형 동적 방정식의 해는 Newmark 방법과 Newton-Raphson 반복법을 혼용하여 적용하여 산정하였다. 본 연구에서 개발한 유한요소 해석프로그램을 사용하여 쉘의 곡률, 화이버 보강각도 및 적층 배열의 변화가 적층 쉘의 기하학적 비선형 동적 거동에 미치는 영향을 상세 분석하였다. 몇 가지 수치해석 결과는 기존 문헌으로부터 얻어진 결과와 잘 일치하는 것으로 나타났다. 본 연구의 새로운 결과는 최대 동적변위에 대한 적층 쉘 구조의 곡률, 화이버 보강각도 그리고 적층 배열 형식과의 중요한 상호관계를 보여준다. 몇 가지 수치해석 예제는 동적 특성을 고려한 적층 쉘 구조를 상세 설계하는데 필요한 가이드라인을 제시할 수 있을 것으로 기대된다.

• Journal of the Korean Data and Information Science Society
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• 제14권2호
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• pp.153-165
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• 2003

This paper considers the likelihood ratio test statistic based on nonlinear regression quantiles estimators in order to test of hypothesis about the regression parameter $\theta_o$ and derives asymptotic distribution of proposed test statistic under the null hypothesis and a sequence of local alternative hypothesis. The paper also investigates asymptotic relative efficiency of the proposed test to the test based on the least squares estimators or the least absolute deviation estimators and gives some examples to illustrate the application of the main result.

• Journal of applied mathematics & informatics
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• 제7권3호
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• pp.719-738
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• 2000

A dual algorithm based on the smooth function proposed by Polyak (1988) is constructed for solving nonlinear programming problems with inequality constraints. It generates a sequence of points converging locally to a Kuhn-Tucker point by solving an unconstrained minimizer of a smooth potential function with a parameter. We study the relationship between eigenvalues of the Hessian of this smooth potential function and the parameter, which is useful for analyzing the effectiveness of the dual algorithm.

• 대한수학회보
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• 제42권2호
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• pp.245-256
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• 2005

We consider the second-order nonlinear difference equation (1) $$\Delta(a_nh(x_{n+1}){\Delta}x_n)+p_{n+1}f(x_{n+1})=0,\;n{\geq}n_0$$ where ${a_n},\;{p_n}$ are sequences of integers with $a_n\;>\;0,\;\{P_n\}$ is a real sequence without any restriction on its sign. hand fare real-valued functions. We obtain some necessary conditions for (1) existing nonoscillatory solutions and sufficient conditions for (1) being oscillatory.

• 대한수학회논문집
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• 제32권4호
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• pp.1025-1031
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• 2017

We prove the uniqueness of solutions for the boundary value problem of certain nonlinear elliptic operators in the setting: Given any continuous function f on the p-harmonic boundary of a complete Riemannian manifold, there exists a unique solution of certain nonlinear elliptic operators, which is a limit of a sequence of solutions of the operators with finite energy in the sense of supremum norm, on the manifold taking the same boundary value at each p-harmonic boundary as that of f.

• 대한수학회지
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• 제44권4호
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• pp.823-834
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• 2007

We introduce a new system of generalized nonlinear mixed quasivariational inequalities and prove the existence and uniqueness of the solution for the system in Hilbert spaces. The main result of this paper is an extension and improvement of the well-known corresponding results in Kim-Kim [16], Noor [21]-[23] and Verma [24]-[26].

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.451-454
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• 1998

This paper proposes a new method of Model Predictive Control (MPC) of nonlinear process by us-ing the measured Volterra kernels as the nonlinear model. A nonlinear dynamical process is usually de-scribed as Volterra kernel representation, In the authors' method, a pseudo-random M-sequence is ar plied to the nonlinear process, and its output is measured. Taking the crosscorrelation between the input and output, we obtain the Volterra kernels up to 3rd order which represent the nonlinear characteristics of the process. By using the measured Volterra kernels, we can construct the nonlinear model for MPC. In applying Model Predictive Control to a nonlinear process, the most important thing is, in general, what kind of nonlinear model should be used. The authors used the measured Volterra kernels of up to 3rd order as the process model. The authors have carried out computer simulations and compared the simulation results for the linear model, the nonlinear model up to 2nd Volterra kernel, and the nonlinear model up to 3rd order Vol-terra kernel. The results of computer simulation show that the use of Valterra kernels of up to 3rd order is most effective for Model Predictive Control of nonlinear dynamical processes.