• 대한수학회보
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• 제33권2호
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• pp.233-241
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• 1996

The study of non-self-adjoint operator algebras on Hilbert space was only beginned by W.B. Arveson[1] in 1974. Recently, such algebras have been found to be of use in physics, in electrical engineering, and in general systems theory. Of particular interest to mathematicians are reflexive algebras with commutative lattices of invariant subspaces.

• 대한수학회논문집
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• 제11권2호
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• pp.495-501
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• 1996

There is currently a regain of interest in ADI (Alternating Direction Implicit) method as a preconditioner for iterative Method for solving large sparse linear systems, because of its suitability for parallel computation. However the classical ADI is not applicable to FE(Finite Element) matrices. In this paper wer propose a Block-ADI method, which is applicable to Finite Element metrices. The new approach is a combination of classical ADI method and domain decompositi on. Also, we provide a partial proof of the convergence based on the results from the regular splittings, in case the discretization metrix is symmetric positive definite.

• 대한수학회보
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• 제51권1호
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• pp.267-285
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• 2014

An upstream scheme based on the pseudostress-velocity mixed formulation is studied to solve convection-dominated Oseen equations. Lagrange multipliers are introduced to treat the trace-free constraint and the lowest order Raviart-Thomas finite element space on rectangular mesh is used. Error analysis for several quantities of interest is given. Particularly, first-order convergence in $L^2$ norm for the velocity is proved. Finally, numerical experiments for various cases are presented to show the efficiency of this method.

• 대한수학회보
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• 제29권1호
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• pp.89-99
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• 1992

In this paper we will prove some theorems on the period and the linear complexity of certain sequences in GF(q) which are generated by combining two sequences in a reasonable way. In fact these theorems are generalizations of the main result in [1]. A sequence of elements of GF(2) is called a binary sequence. In recent years considerable interest has been shown in the generation of binary sequences which have good properties. Such binary sequences play an important role in a stream cipher system.

• 한국수학교육학회:학술대회논문집
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• 한국수학교육학회 2010년도 제44회 전국수학교육연구대회
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• pp.205-212
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• 2010

Reflection has been of interest to educators as Dewey discussed it. Information about how teachers interpret and analyze their students' learning would help us understand difficulties in teaching and learning. Moreover, it can be useful for teacher education by improving teaching methods. In this study, I investigated four U.S.A. mathematics teachers in a middle school. In this paper, I discussed Assess instances among the teachers' reflections on their students' thinking and changes of the reflections as time went by.

• 대한수학회지
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• 제34권1호
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• pp.227-235
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• 1997

In recent years there has been much interest in the study of groups satisfying various permutability conditions (see, for instance, [1], [2] and [3]). More recently, the following condition has been studied: for some , if S is any subset of m elements of a group G, then $$\mid$S^2$\mid$ < m^2$ (where, for subsets A, B of G, AB stands for ${ab; a \in A, b \in B}$).

• 대한수학회지
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• 제44권3호
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• pp.605-613
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• 2007

Main interest of the present paper is to investigate the criticality of characteristic vector fields on almost cosymplectic manifolds. Killing critical characteristic vector fields are absolute minima. This paper contains some examples of non-Killing critical characteristic vector fields.

• 대한수학회논문집
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• 제23권2호
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• pp.295-305
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• 2008

This paper demonstrates how composite-exponential-fitting interpolation rules can be constructed to fit an oscillatory function using not only pointwise values of that function but also of that functions's derivative on a closed and bounded interval of interest. This is done in the framework of exponential-fitting techniques. These rules extend the classical composite cubic Hermite interpolating polynomials in the sense that they become the classical composite polynomials as a parameter tends to zero. Some examples are provided to compare the newly constructed rules with the classical composite cubic Hermite interpolating polynomials (or recently developed interpolation rules).

• Korea-Australia Rheology Journal
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• 제19권3호
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• pp.117-123
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• 2007

There has been considerable interest in recent years in field-responsive suspensions, which are of some importance in industry in many different applications. The microstructure of these materials is a significant issue which can be probed by rheological measurements. In this study, measurements were made of a magnetorheological fluid (MRF) under steady and oscillatory shear flow, with and without a magnetic field. Mathematical inversion was used to derive the relaxation time spectrum of the MRF from oscillatory shear data. Experimental evidence is presented of the gel-like properties of this MRF.

• 전자공학회지
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• 제38권1호
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• pp.31-43
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• 2011

The mathematical foundations of the compressive sensing which goes against the common wisdom of data acquisition (the Nyquist-Shannon theorem) is reviewed. The compressive sensing asserts that one can reconstruct images or signals of interest accurately from a number of samples far smaller than the desired resolution of the image (e.g., the number of pixels in the image). The compressive sensing has far reaching implications. It suggests the new data acquisition protocols that translates analog information to digital form with fewer sensors considered necessary.