• School Mathematics
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• v.4 no.4
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• pp.555-563
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• 2002

The purpose of this paper is to try formulating a working definition of connection of informal and formal mathematical knowledge. Many researchers have suggested that informal mathematical knowledge should be connected with school mathematics in the process of learning and teaching it. It is because informal mathematical knowledge might play a important role as a cognitive anchor for understanding school mathematics. To implement the connection of them we need to know what the connection means. In this paper, the connection between informal and formal mathematical knowledge refers to the making of relationship between common attributions involved with the two knowledge. To make it clear, it is discussed that informal knowledge consists of two properties of procedures and conceptions as well as formal mathematical knowledge does. Then, it is possible to make a connection of them. Now it is time to make contribution of our efforts to develop appropriate models to connect informal and formal mathematical knowledge.

• Bulletin of the Korean Mathematical Society
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• v.61 no.4
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• pp.897-906
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• 2024

On a Hermitian manifold, the Chern connection can induce a metric connection on the background Riemannian manifold. We call the sectional curvature of the metric connection induced by the Chern connection the Chern sectional curvature of this Hermitian manifold. First, we derive expression of the Chern sectional curvature in local complex coordinates. As an application, we find that a Hermitian metric is Kähler if the Riemann sectional curvature and the Chern sectional curvature coincide. As subsequent results, Ricci curvature and scalar curvature of the metric connection induced by the Chern connection are obtained.

• The Mathematical Education
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• v.51 no.4
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• pp.455-469
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• 2012

Given the importance of mathematical connections in instruction, this paper analyzed the objects and the methods of mathematical connections according to the lesson flow featured in 20 elementary lessons selected as effective instructional methods by local educational offices in Korea. Mathematical connections tended to occur mainly in the introduction, the first activity, and the sum-up period of each lesson. The connection between mathematical concept and procedure was the most popular followed by the connection between concept and real-life context. The most prevalent method of mathematical connections was through communication, specifically the communication between the teacher and students, followed by representation. Overall it seems that the objects and the methods of mathematical connections were diverse and prevalent, but the detailed analysis of such cases showed the lack of meaningful connection. These results urge us to investigate reasons behind these seemingly good features but not-enough connections, and to suggest implications for well-connected mathematics teaching.

• Journal of the Chungcheong Mathematical Society
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• v.25 no.4
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• pp.599-608
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• 2012

In [2], [8], the author studied the characteristic connection as a good substitute for the Levi-Civita connection. In this paper, we consider the space $U(3)=(U(1){\times}U(1){\times}U(1))$ with an almost Hermitian structure which admits a characteristic connection and compute the characteristic connection concretely.

• Honam Mathematical Journal
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• v.46 no.1
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• pp.114-119
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• 2024

In this article, we consider a connection of vectorial type in some sense which is not a metric connection. We will then discuss when this connection $\tilde{\nabla}^*$ has parallel torsion T, that is, $\tilde{\nabla}^*T=0$.

• Journal of the Korean Mathematical Society
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• v.55 no.5
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• pp.1075-1089
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• 2018

We define a new connection on semi-Riemannian manifolds, which is a non-symmetric and non-metric connection. We say that this connection is an (${\ell}$, m)-type connection. Semi-symmetric non-metric connection and non-metric ${\phi}$-symmetric connection are two important examples of this connection such that (${\ell}$, m) = (1, 0) and (${\ell}$, m) = (0, 1), respectively. In this paper, we study lightlike hypersurfaces of an indefinite trans-Sasakian manifold with an (${\ell}$, m)-type connection.

• Bulletin of the Korean Mathematical Society
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• v.53 no.4
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• pp.1171-1184
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• 2016

We define a new connection on semi-Riemannian manifolds, which is called a symmetric connection of type (${\ell}$, m). Semi-symmetric connection and quarter-symmetric connection are two examples of this connection such that $({\ell},m)=(1,0)$ and $({\ell},m)=(0,1)$ respectively. In this paper, we study lightlike hypersurfaces of an indefinite Kaehler manifold endowed with a symmetric metric connection of type (${\ell}$, m).

• Bulletin of the Korean Mathematical Society
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• v.54 no.2
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• pp.619-632
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• 2017

We define a new connection on semi-Riemannian manifold, which is called a non-metric ${\phi}$-symmetric connection. Semi-symmetric non-metric connection and quarter-symmetric non-metric connection are two impotent examples of this connection. The purpose of this paper is to study the geometry of lightlike hypersurfaces of an indefinite Kaehler manifold with a non-metric ${\phi}$-symmetric connection.

• Honam Mathematical Journal
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• v.27 no.3
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• pp.515-523
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• 2005

We investigate change of the connection induced by the conformal change in 8-dimensional g-unified field theory. These topics will be studied for the second class with the first category in 8-dimensional case.

• Bulletin of the Korean Mathematical Society
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• v.50 no.5
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• pp.1567-1586
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• 2013

In this paper, we study the Einstein multiply warped products with a semi-symmetric non-metric connection and the multiply warped products with a semi-symmetric non-metric connection with constant scalar curvature, we apply our results to generalized Robertson-Walker spacetimes with a semi-symmetric non-metric connection and generalized Kasner spacetimes with a semi-symmetric non-metric connection and find some new examples of Einstein affine manifolds and affine manifolds with constant scalar curvature. We also consider the multiply warped products with an affine connection with a zero torsion.