• 한국수학교육학회지시리즈E:수학교육논문집
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• 제28권1호
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• pp.155-178
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• 2014

본 연구는 대수 문제에 대한 해법 자체가 일반성을 지향한다는 사실에도 불구하고, 다수의 학생들은 해법 수행 후에도 그것의 일반성을 인식하지 못할 수 있다는 문제 제기로부터 출발한다. 즉, 대수 해법의 일반성에 대한 이해가 결여된 체, 대수 해법 수행이 이루어지고 있을지도 모른다는 의구심이 제기된다. 이 문제를 조사하여 학생 인식의 구체적 특징을 파악하고, 아울러 인식 전환을 가능하게 하는 요인을 찾음으로써, 교육적 시사점을 얻는 것을 목적으로 한다. 이를 위해 중학교 3학년 한 학급 학생들을 대상으로 대수 해법 일반성에 대한 인식을 조사하였으며, 그 결과 70%에 해당하는 학생들이 대수 일반성 인식 결여를 나타내었다. 이들 중 대수 해법의 일반성 인식 결여가 명백한 네 명의 학생들과 개별 면담을 가짐으로써, 인지적 특성을 파악해 보았다. 또한 이들에게 해법 일반성 인식에 필요한 요소를 분석하여 얻은 세 활동(개별 결과 동일성 확인, 상이 대수 해법 동일성 확인, 대수의 임의성 확인) 투입 이후 나타나는 인식 변화를 관찰, 분석하였다. 개별 면담을 가진 네 사례는 하나의 활동만으로 인식 개선한 한 사례와 세 활동을 통한 점진적 인식 개선한 두 사례, 그리고 인식 전환에 실패한 한 사례로 구분되었다. 이러한 결과를 토대로 대수에서 해법의 일반성에 대한 인식과 세 활동의 효과, 그리고 시사점을 논의하였다.

• 전력전자학회논문지
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• 제27권6호
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• pp.471-480
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• 2022

Inductive power transfer (IPT) is an attractive power transmission solution that is already used in many applications. In the IPT system, optimal coil design is essential to achieve high power efficiency, but the effective design method is yet to be investigated. The inductance formula and finite element method (FEM) are popular means to link the coil geometric parameters and circuit parameters; however, the former lacks generality and accuracy, and the latter consumes much computation time. This study proposes a novel coil design method to achieve speed and generality without much loss of accuracy. By introducing one-turn permeance simulation in each FEM phase combined with curve fitting and optimization by MATLAB in the efficiency calculation phase, the iteration number of FEM can be considerably reduced, and the generality can be retained. The proposed method is verified through a 100 W IPT system experiment.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1287-1296
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• 2003

In this paper the dynamic analysis of the Macpherson strut motor-vehicle suspension system is presented. The equations of motion are formulated using a two-step transformation. Initially, the equations of motion are derived for a dynamically equivalent constrained system of particles that replaces the rigid bodies by applying Newton's second law The equations of motion are then transformed to a reduced set in terms of the relative joint variables. Use of both Cartesian and joint variables produces an efficient set of equations without loss of generality For open chains, this process automatically eliminates all of the non-working constraint forces and leads to an efficient solution and integration of the equations of motion. For closed loops, suitable joints should be cut and few cut-joints constraint equations should be included for each closed chain. The chosen suspension includes open and closed loops with quarter-car model. The results of the simulation indicate the simplicity and generality of the dynamic formulation.

• Structural Engineering and Mechanics
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• 제72권4호
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• pp.491-502
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• 2019

This paper explores the analytical buckling solution of rectangular thin plates by the finite integral transform method. Although several analytical and numerical developments have been made, a benchmark analytical solution is still very few due to the mathematical complexity of solving high order partial differential equations. In solution procedure, the governing high order partial differential equation with specified boundary conditions is converted into a system of linear algebraic equations and the analytical solution is obtained classically. The primary advantage of the present method is its simplicity and generality and does not need to pre-determine the deflection function which makes the solving procedure much reasonable. Another advantage of the method is that the analytical solutions obtained converge rapidly due to utilization of the sum functions. The application of the method is extensive and can also handle moderately thick and thick elastic plates as well as bending and vibration problems. The present results are validated by extensive numerical comparison with the FEA using (ABAQUS) software and the existing analytical solutions which show satisfactory agreement.

• Structural Engineering and Mechanics
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• 제12권4호
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• pp.363-376
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• 2001

Sandwich plates are widely used in lightweight design due to their high strength and stiffness to weight ratio. Due to the heterogeneous structure of sandwich plates, they can exhibit local instabilities (wrinkling), which lead to a sudden loss of stiffness in the structure. This paper presents an analytical solution to the wrinkling problem of sandwich plates. The solution is based on the Rayleigh-Ritz method, by assuming an appropriate deformation field. In contrast to the other approaches up to now, this model takes arbitrary and different orthotropic face layers, finite core thickness and orthotropic core material into account. This approach is the first to cover the wrinkling of unsymmetric sandwiches and sandwiches composed of orthotropic FRP face layers, which are most common in advanced lightweight design. Despite the generality of the solution, the computational effort is kept within bounds. The results have been verified using other analytical solutions and unit cell 3D FE calculations.

• Journal of applied mathematics & informatics
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• 제9권2호
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• pp.695-703
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• 2002

The fractional order evolutionary integral equations have been considered by first author in [6], the existence, uniqueness and some other properties of the solution have been proved. Here we study the continuation of the solution and its fractional order derivative. Also we study the generality of this problem and prove that the fractional order diffusion problem, the fractional order wave problem and the initial value problem of the equation of evolution are special cases of it. The abstract diffusion-wave problem will be given also as an application.

• 전자공학회논문지B
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• 제29B권3호
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• pp.6-15
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• 1992

This paper proposes a method for the global optimization of redundancy over the whole task period for a kinematically redundant robot. The necessary conditions based on the calculus of variations for an integral type cost criterion result in a second-order differential equation. For a cyclic task, the periodic boundary conditions due to conservativity requirements are discussed. We refine the two-point boundary value problem to an initial value adjustment problem and suggest a numerical search method for providing the conservative global optimal solution using the gradient projection method. Since the initial joint velocity is parameterized with the number of the redundancy, we only search the parameter value in the space of as many dimensions as the number of degrees of redundancy. We show through numerical examples that multiple nonhomotopic extremal solutions and the generality of the proposed method by considering the dynamics of a robot.

• Tribology and Lubricants
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• 제4권2호
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• pp.28-35
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• 1988

A general and efficient algorithm is proposed for the analysis of the frictionless elastic contact problems. It utilizes a simplex-type algorithm with a modified entry rule and incoporates finite element method to obtain flexibility matrices. The algorithmic solution is compared with the Hertzian solution for the contact problem between two cylinders to prove its accuracy and the contact problem between pin and piston rod is solved and compared with the numerical results of Frankavilla and Zienkiewicz to demonstrate the generality and effectiveness of the suggested algorithm. The contact problem between mating involute gear teeth at the worst load position is considered. The computed contact stress is smaller than the result of Hertz's theory applied to the contact between two kinematically equivalent discs and the contact area is larger than that of Hertz's theory.

• 한국측량학회지
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• 제31권6_2호
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• pp.577-583
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• 2013

Recently, massive archives of ground information imagery from new sensors have become available. To establish a functional relationship between the image and the ground space, sensor models are required. The rational functional model (RFM), which is used as an alternative to the rigorous sensor model, is an attractive option owing to its generality and simplicity. To determine the rational polynomial coefficients (RPC) in RFM, however, we encounter the problem of obtaining a stable solution. The design matrix for solutions is usually ill-conditioned in the experiments. To solve this unstable solution problem, regularization techniques are generally used. In this paper, we describe the effective determination of the optimal regularization parameter in the regularization technique during RPC derivation. A brief mathematical background of RFM is presented, followed by numerical approaches for effective determination of the optimal regularization parameter using the Euler Method. Experiments are performed assuming that a tilted aerial image is taken with a known rigorous sensor. To show the effectiveness, calculation time and RMSE between L-curve method and proposed method is compared.

• 한국정밀공학회지
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• 제9권1호
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• pp.34-43
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• 1992

Computer Intergrated Manufacturing (CIM) is an emerging technology which aims at the total automation of a manufacturing system. Despite the extensive research on CIM in this decade, total automation seems to be far from reality for many reasons. In this study, the problems of implementing a CIM system are analyzed and a solution method is suggested. A set of software has been developed and tested for a workstation cotroller which controls closely integrated equipment in the low level of a flexible manufacturing system. The functions of the programs are communications between machines and computers and control of workstation scheduling. The software group is developed on IBM OS/2 operating system with 'c' language to enhance the portability. The usage of the software is presented to users through the Presentation Manager which is menu handler of OS/2 system. Although the software is developed for limited machine equipment, the scheme can be adopted to various machines due to the generality.