• Journal of Mechanical Science and Technology
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• 제16권11호
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• pp.1522-1539
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• 2002

In the present study, an explicit algebraic stress model is shown to be the exact tensor representation of algebraic stress model by directly solving a set of algebraic equations without resort to tensor representation theory. This repeals the constraints on the Reynolds stress, which are based on the principle of material frame indifference and positive semi-definiteness. An a priori test of the explicit algebraic stress model is carried out by using the DNS database for a fully developed channel flow at Rer = 135. It is confirmed that two-point correlation function between the velocity fluctuation and the Laplacians of the pressure-gradient i s anisotropic and asymmetric in the wall-normal direction. Thus, a novel composite algebraic Reynolds stress model is proposed and applied to the channel flow calculation, which incorporates non-local effect in the algebraic framework to predict near-wall behavior correctly.

• 한국학교수학회논문집
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• 제17권4호
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• pp.507-539
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• 2014

문자 기호 사용으로 대표되는 대수는 수학 전반에 그 영향력을 행사하는 중요한 도구로 자리매김하게 되었다. 이러한 대수를 적절히 활용하기 위해서는 무엇보다 주어진 문제 상황을 적합한 대수적 표상으로 전환하는 작업이 요구된다. 그러나 문장제에 관한 몇 가지 연구로부터 이러한 전환의 어려움이 보고되고 있다. 본 연구에서는 학생들이 주어진 문장 표상과 기하 표상 각각을 대수적 표상으로 전환 및 정교화하는 과정을 살펴보는데 초점을 두었다. 중학교 1학년 학생 29명을 대상으로 하여 문장으로 기술된 상황과 도형 표현이 추가된 상황을 제시하고 각 상황에서 요구하는 바를 대수적 표상으로 전환하는 능력을 조사한 결과 도형 표현을 대수적 표상으로 전환하는 하나의 문항을 제외하고 나머지 3개의 문항에서 10% 내외의 학생이 부적절한 응답을 하였다. 나아가 그 중 임의 추출한 네 명을 개별 면담함으로써 사고 특징 및 대수적 표상 정교화를 돕는 요인을 조사하였다. 그 결과, 대수 표상 정교화 과정은 급진적이 아닌 점진적 개선 과정임을 확인할 수 있었다. 그리고 대수적 표상 정교화를 요하는 문제에 대해 문제 요구 사항에 대한 오해가 있을 수 있음을 확인할 수 있었다. 또한 자신의 대수적 표상에 대한 설명과 구체적 수치 상황 제시가 정교화에 도움이 되는 요인으로 작용하는 것을 목격하였으며, 아울러 정교화의 경험은 전이력을 가질 수 있음을 확인할 수 있었다. 한편, 변수에 관한 오개념 등식 설정에 고착된 사고는 표상 전환의 방해 요소로 작용할 수 있음을 알 수 있었다. 이러한 결과로부터 대수적 표상 전환 및 정교화를 돕기 위한 몇 가지 교육적 시사점을 도출하였다.

• 자연과학논문집
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• 제8권2호
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• pp.17-20
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• 1996

Fiber의 dimension이 일일 때, Equivariant Serre problem이 실 대수 범주에서 맞다는 것을 보였다. 즉 실 표현공간 위에서의 equivariant line bundle은 실 표현공간과 어떤 G-module의 product bundle과 동치임을 보였다.

• East Asian mathematical journal
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• 제19권2호
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• pp.317-335
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• 2003

In this paper, we characterize SL(2, $\mathbb{C}$)-representations of an n-periodic link $\tilde{L}$ in terms of SL(2, $\mathbb{C}$)-representations of its quotient link L and express the SL(2, $\mathbb{C}$)-representation variety R($\tilde{L}$) of $\tilde{L}$ as the union of n affine algebraic subsets which have the same dimension. Also, we show that the dimension of R($\tilde{L}$) is bounded by the dimensions of affine algebraic subsets of the SL(2, $\mathbb{C}$)-representation variety R(L) of its quotient link L.

• 대한수학회지
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• 제40권3호
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• pp.447-460
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• 2003

In this paper we study the non-degenerate n-connected canonical domains with n>1 related to the conjecture of S. Bell in [4]. They are connected to the algebraic property of the Bergman kernel and the Szego kernel. We characterize the non-degenerate doubly connected canonical domains.

• 대한수학회지
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• 제42권4호
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• pp.695-708
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• 2005

Certain observations about formal Dirichlet series whose coefficients are arithmetic functions are made. These include for example algebraic independence and representation as infinite series of logarithms.

• 한국수학사학회지
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• 제28권4호
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• pp.167-179
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• 2015

We study the solution of truncated series of Lee Sang-hyeog with the aspect of visualization. Lee Sang-hyeog solved a problem of truncated series by 4 ways: Shen Kuo' series method, splitting method, difference sequence method, and Ban Chu Cha method. As the structure and solution of truncated series in tertiary number is already clarified with algebraic symbols in some previous research, we express and explain it by visual representation. The explanation and proof of algebraic symbols about truncated series is clear in mathematical aspects; however, it has a lot of difficulties in the aspects of understanding. In other words, it is more effective in the educational situations to provide algebraic symbols after the intuitive understanding of structure and solution of truncated series with visual representation.

• 대한수학회보
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• 제29권1호
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• pp.41-55
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• 1992

The characteristic free representation theory of the general linear group is one of the powerful tools in the study of invariant theory, algebraic geometry, and commutative algebra. Recently the study of such representations became a popular theme. In this paper we study the representation-theoretic structures of the symmetric algebra and the exterior algebra over a commutative ring with unity 1.

• 한국수학교육학회지시리즈A:수학교육
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• 제42권5호
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• pp.697-706
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• 2003

In this paper we consider the equality sign as a mathematical concept and investigate its meaning, errors made by students, and subject matter knowledge of mathematics teacher in view of The Model of Mathematic al Concept Analysis, arithmetic-algebraic thinking, and some examples. The equality sign = is a symbol most frequently used in school mathematics. But its meanings vary accor ding to situations where it is used, say, objects placed on both sides, and involve not only ordinary meanings but also mathematical ideas. The Model of Mathematical Concept Analysis in school mathematics consists of Ordinary meaning, Mathematical idea, Representation, and their relationships. To understand a mathematical concept means to understand its ordinary meanings, mathematical ideas immanent in it, its various representations, and their relationships. Like other concepts in school mathematics, the equality sign should be also understood and analysed in vie w of a mathematical concept.

• 한국수학사학회지
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• 제26권5_6호
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• pp.355-370
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• 2013

Thomas Harriot has been introduced in middle school textbooks as a great mathematician who created the sign of inequality. This study is about Harriot's symbolism and the theory of equation. Harriot made symbols of mathematical concepts and operations and used the algebraic visual representation which were combinations of symbols. He also stated solving equations in numbers, canonical, and by reduction. His epoch-making inventions of algebraic equation using notation of operation and letters are similar to recent mathematical representation. This study which reveals Harriot's contribution to general and structural approach of mathematical solution shows many developments of algebra in 16th and 17th centuries from Viete to Harriot and from Harriot to Descartes.