• Structural Engineering and Mechanics
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• 제61권6호
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• pp.807-816
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• 2017

In this paper, we introduce an efficient new model reduction method, named the automated static condensation method, which is developed for the local analysis of large finite element models. The algebraic multilevel substructuring procedure is modified appropriately, and then applied to the original static condensation method. The retained substructure, which is the local finite element model to be analyzed, is defined, and then the remaining part of the global model is automatically partitioned into many omitted substructures in an algebraic perspective. For an efficient condensation procedure, a substructural tree diagram and substructural sets are established. Using these, the omitted substructures are sequentially condensed into the retained substructure to construct the reduced model. Using several large practical engineering problems, the performance of the proposed method is demonstrated in terms of its solution accuracy and computational efficiency, compared to the original static condensation method and the superelement technique.

• 대한수학회보
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• 제35권3호
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• pp.397-408
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• 1998

We often use the Hausdorff dimension as a tool of measuring how complicate the fractal is. But it is usually very difficult to calculate that value. So there have been many tries to find the dimension of the given set and most of these are related to the density theorem of invariant measure. The aims of this paper are to introduce the k-irreducible subsimilar sets as a generalization of the set defined by V.Drobot and J.Turner in ([1]) and calculate their Hausdorff dimensions by using algebraic methods.

• Korean Journal of Mathematics
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• 제26권3호
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• pp.503-517
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• 2018

Keeping in view the expediency of soft sets in algebraic structures and as a mathematical approach to vagueness, in this paper the concept of lattice ordered soft near rings is introduced. Different properties of lattice ordered soft near rings by using some operations of soft sets are investigated. The concept of idealistic soft near rings with respect to lattice ordered soft near ring homomorphisms is deliberated.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.523-528
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• 1990

This paper discusses the problem of designing an observation function as coarsest as possible in supervisory control of discrete event dynamic systems. Some algebraic properties of two sets consisting of observation functions for which the given desirable behavior is realizable are investigated:these sets with a partial ordering turn out not to possess largest elements. Two natural methods of obtaining an observation function, which is frequently coarser than the identity mapping, are also presented. An example illustrates the use of these methods.

• 호남수학학술지
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• 제34권4호
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• pp.495-504
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• 2012

Let G be a semialgebraic group and M a proper semi-algebraic G-set which is locally complete. In this paper we show that the orbit space M/G has a semialgebraic structure such that the orbit map is semialgebraic.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제25권2호
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• pp.473-495
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• 2011

중등학교 전반에 걸쳐 항등원, 역원, 교환법칙, 결합법칙, 분배법칙이 다루어지고 있다. 이는 대수적 구조의 조장으로 이들익 성립 여부에 따라 군, 환, 체로 결정되게 된다. 그런데 이을 대수적 구조의 조건들은 어떤 의미를 가지며, 이들 조건들이 만족됨에 따라 정해지는 대수적 구조는 어떤 의미를 가지는지 의외에 대한 지도는 이루어지고 있지 않다. 그로인해 학생들은 이들 조건을 대상 집합의 특성이라는 결과적 측면으로 받아들이고 있다. 본 연구에서는 수 체계와 다항방정식의 해법과의 연결성을 고려하여 이러한 조건들파 대수적 구조의 의의를 교수학적으로 조직화하기로 한다. 교수학적 조직화란 학습자의 자연스러운 사고활동을 위한 모델을 구성하는 것으로 역사적 발생과 함께 현대수학의 관점을 고려하여 수학적 개념이 필연성과 개연성을 가진 산물임을 경험시키도록 흐름을 구성하는 것이다. 이를 위해 본 연구에서는 다항방정식의 해법을 보장하기 위한 수학적 개념으로 대수적 구조를 파악하고, 수 체계의 의미를 지도하는 영재교육을 위한 프로그램을 개발하였다. 그리고 이를 교수실험 하여 그 효용성을 알아보았다.

• Structural Engineering and Mechanics
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• 제22권3호
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• pp.331-349
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• 2006

The stresses and deflections in a laminated rectangular plate under thermal vibration are determined by using the moving least squares differential quadrature (MLSDQ) method based on the first order shear deformation theory. The weighting coefficients used in MLSDQ approximation are obtained through a fast computation of the MLS shape functions and their partial derivatives. By using this method, the governing differential equations are transformed into sets of linear homogeneous algebraic equations in terms of the displacement components at each discrete point. Boundary conditions are implemented through discrete grid points by constraining displacements, bending moments and rotations of the plate. Solving this set of algebraic equations yields the displacement components. Then substituting these displacements into the constitutive equation, we obtain the stresses. The approximate solutions for stress and deflection of laminated plate with cross layer under thermal load are obtained. Numerical results show that the MLSDQ method provides rapidly convergent and accurate solutions for calculating the stresses and deflections in a multi-layered plate of cross ply laminate subjected to thermal vibration of sinusoidal temperature including shear deformation with a few grid points.

• 대한수학회지
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• 제49권1호
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• pp.17-30
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• 2012

Let D be an arbitrary domain in $\mathbb{C}^n$, n > 1, and $M{\subset}{\partial}D$ be an open piece of the boundary. Suppose that M is connected and ${\partial}D$ is smooth real-analytic of finite type (in the sense of D'Angelo) in a neighborhood of $\bar{M}$. Let f : $D{\rightarrow}\mathbb{C}^n$ be a holomorphic correspondence such that the cluster set $cl_f$(M) is contained in a smooth closed real-algebraic hypersurface M' in $\mathbb{C}^n$ of finite type. It is shown that if f extends continuously to some open peace of M, then f extends as a holomorphic correspondence across M. As an application, we prove that any proper holomorphic correspondence from a bounded domain D in $\mathbb{C}^n$ with smooth real-analytic boundary onto a bounded domain D' in $\mathbb{C}^n$ with smooth real-algebraic boundary extends as a holomorphic correspondence to a neighborhood of $\bar{D}$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.541-547
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• 2000

This paper presents the closed-form forward kinematics of the 6-6 Stewart platform of planar base and moving platform. Based on algebraic elimination method and with one extra linear sensor, it first derives an 8th-degree univariate equation and then finds tentative solution sets out of which the actual solution is to be selected. In order to provide more exact solution despite the error between measured sensor value and the theoretical one, a correction method is also used. The overall procedure requires so little computation time that it can be efficiently used for realtime applications. In addition, unlike the iterative schemes e.g. Newton-Raphson, the algorithm does not require initial estimates of solution and is free of the problems that it does not converge to actual solution within limited time. The presented method has been implemented in C language and a numerical example is given to confirm the effectiveness and accuracy of the developed algorithm.

• 한국지능시스템학회논문지
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• 제17권7호
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• pp.981-985
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• 2007

In this paper, we investigate the properties of residuated partially ordered sets as weak definitions of algebraic structures in many valued logics. We study the left(resp. right) residuated semigroups induced by right(resp. left) associated map. We give their examples.