• Structural Engineering and Mechanics
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• 제16권1호
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• pp.35-46
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• 2003

The histories and distributions of dynamic stresses in an orthotropic hollow cylinder under sinusoidal impact load are obtained by making use of eigenfunction expansion method in this paper. Dynamic equations for axially symmetric orthotropic problem are founded and results are carried out for a practical example in which an orthotropic hollow cylinder is in initially at rest and subjected to a dynamic interior pressure $p(t)=-{\sigma}_0(sin{\alpha}t+1)$. The features of the solution appear the propagation of the cylindrical waves. The other hand, a dynamic finite element solution for the same problem is also got by making use of structural software (ABAQUS) program. Comparing theoretical solution with finite element solution, it can be found that two kinds of results obtained by two different solving methods are suitably approached. Thus, it is further concluded that the method and computing process of the theoretical solution are effective and accurate.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.459-468
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• 2009

Analysis of the uncertainty to have engineering solution of gas-dynamic and hydrodynamic problems is based on the comparison the prospective engineering solution with experimental result. In this paper, the mathematical model to estimate heat flux along gas-dynamic channel wall and the solution sequence are shown. Statistical information and generalizing experimental characteristics about gas- and hydro-dynamic channels were applied to the mathematical model. As the results, it is possible to draw a conclusion that models of the integrated approach, using the averaged statistical data of generalizing characteristics for a turbulent flow, without consideration of the turbulent mechanism (characteristic pulsations), can predict a nominal operating regime for gas-dynamic and hydrodynamic systems. The probable deviation of operating regime for newly designed the gas-dynamic channel can achieve 20% from a regime predicted on a basis 1-D or 3-D modelling irrespective of a kind of used models.

• 한국해양공학회지
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• 제24권1호
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• pp.34-38
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• 2010

An analytical solution procedure for the dynamic response of beams with variable properties is developed by using an asymptotic solution and the Green's function. This asymptotic closed form solution is derived for the transverse vibration of beams under the assumption of slowly varying properties, such as mass, cross-section, tension etc., along the beam length. However, this solution is still found to be very accurate even in the case of large variation, such as step change in cross-section, mass, and tension. Therefore, this derived asymptotic closed form solution and the Green's function can be easily applied to find dynamic responses for various kind of beam vibration problems.

• 지능정보연구
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• 제17권3호
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• pp.43-61
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• 2011

본 연구는 사용자의 정적, 외부환경과 연관된 동적 상황정보와 사회적 관계와 연관된 개인적 상황정보들을 의사결정 요소로서 고려한 의사결정의 동적 변환(Dynamic Adaptation)을 제안한다. 즉, 의사결정자의 정적, 외재적 정보보다 과거의 경험, 주관적 선호도 및 사회적 관계와 연관된 상황정보(Social Context)를 의사결정에 동적으로 반영하고 동시에 의사결정 해의 사용시점에서의 가용성에 따라 유용 가능한 대안을 추출하는 방법론을 제안하고자 한다. 이를 위해, 정적, 외재적 및 사회적 상황정보를 이용하여 의사결정 추론한다. 추론은 의사결정자의 과거 경험에 기반한 사례기반 추론과 해당 의사결정 결과가 가용하지 않을 경우 수정을 위한 제약식 만족추론으로 이루어진다. 이를 위해 개인적 경험 등의 정보에 기반한 '문제상황 온톨로지'(Problem Context Ontology)와 집단의 경험적 지식에 기반한 '솔루션 온톨로지'(Solution Ontology)를 구축하였다. 의사결정단계는 상황정보 인식 및 문제상황 온톨로지에 매핑하는 단계, 경험적 사례로부터 문제상황에 가장 적합한 사례를 선택하는 단계, 생성된 솔루션이 가용하지 않을 경우 솔루션 온톨로지와 제약식 만족추론을 통해 새로운 대안을 생성하는 단계로 이루어진다. 본 방법론을 모임에 적합한 식당을 제안하는 예제를 적용함으로써 타당성을 검증하였다. 또한 실험을 통해 사회적 상황정보를 고려하여 생성된 의사결정대안이 그렇지 않은 경우보다 의사결정자의 만족도를 향상시켰으며, 생성된 의사결정대안이 가용하지 않은 경우 제약조건식과 솔루션 온톨로지를 이용해 생성한 대안이 유의미함을 검증하였다.

• Coupled systems mechanics
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• 제9권6호
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• pp.563-573
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• 2020

Dynamic responses of a laminated composite cantilever beam under a harmonic are investigated in this study. The governing equations of problem are derived by using the Lagrange procedure. The Timoshenko beam theory is considered and the Ritz method is implemented in the solution of the problem. The algebraic polynomials are used with the trivial functions for the Ritz method. In the solution of dynamic problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of load parameter, the fiber orientation angles and stacking sequence of laminas on the dynamic responses of the laminated beam are investigated.

• 대한산업공학회지
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• 제12권1호
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• pp.81-94
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• 1986

A shortest path dynamic programming formulation is proposed and attemped to solve an uncapacitated expansion sequencing problem. It is also compared with the Extended Binary State Space approach with total capacity. Difficulties and merits associated with the formulation are discussed. The shortest path dynamic programming lacks the separability condition and an optimal solution is not guaranteed. However it has other merits and seems to be the practical solution procedure for the expansion sequencing problem in a sense that it finds near optimal solution with less state evaluations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.156-161
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• 1994

In this paper, we consider an optimal control problem of a nonlinear stochastic system. Dynamic programming approach is employed for the formulation of a stochastic optimal control problem. As an optimality condition, dynamic programming equation so called the Bellman equation is obtained, which seldom yields an analytical solution, even very difficult to solve numerically. We obtain the numerical solution of the Bellman equation using an algorithm based on the finite difference approximation and the contraction mapping method. Optimal controls are constructed through the solution process of the Bellman equation. We also construct a test case in order to investigate the actual performance of the algorithm.

• 대한기계학회논문집
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• 제19권5호
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• pp.1243-1250
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• 1995

For the numerical solution of frictional dynamic contact problems, correct contact points and displacements are determined by iteratively reducing the displacement error vector monotonically toward zero And spurious oscillations are prevented from the solution by enforcing the velocity and acceleration compatibilities of the contact points with the corresponding error vectors. Numerical simulations are conducted to demonstrate the accuracy of the solution and the necessity of the velocity and acceleration compatibilities on the contact surface.

• 대한기계학회논문집A
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• 제22권3호
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• pp.519-528
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• 1998

A numerical method is presented for the dynamic analysis of cam and follower. Contact and separation between the cam and the follower are analyzed by imposing dynamic contact condition. The correct solution is obtained without spurious oscillation by imposing the velocity and acceleration constraints as well as the displacement constraint on the possible contact point. The constraints are satisfied by iteratively reducing the constraint errors toward zero, and a simple time integration of ordinary differential equation is employed for the solution of the equation of motion. The solution procedure associated with the iterative scheme is presented, and numerical simulations are conducted to demonstrate the accuracy of the solution.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.429-436
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• 2002

The current work presents an analysis algorithm for the modal analysis for the dynamic behaviors of offshore structures with concepts of mass perturbation influence term. The mass perturbation concept by using the term, presented in this paper offers an efficient solution procedure for dynamical response problems of offshore structures. The basis of the proposed method is the mass perturbation influence concepts associated with natural frequencies and mode shapes and mass properties of the given structure. The mathematical formulation of the mass perturbation influence method is described. New solution procedures for dynamics analysis are developed, followed by illustrative example problems, which deal with the effectiveness of the new solution procedures for the dynamic analysis of offshore structures. The solution procedures presented herein is compact and computationally simple.