• 호남수학학술지
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• 제31권3호
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• pp.279-292
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• 2009

As a survey-type article, the paper reviews some results on a regular covering space in digital covering theory. The recent paper [10](see also [12]) established the notion of regular covering space in digital covering theory and studied its various properties. Besides, the papers [14, 16] developed a discrete Deck's transformation group of a digital covering. In this paper we study further their properties. By using these properties, we can classify digital covering spaces. Finally, the paper proposes an open problem.

• 천문학회보
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• 제44권2호
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• pp.40.4-40.4
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• 2019

Interplanetary coronal mass ejections (ICMEs) are regarded as one of the most powerful sources of space weather disturbances observed near the Earth orbit (1 AU). In this study, we aim at investigating the relation between these disturbances and the physical properties of an ICME. Toward this end, we used an spheromak-type ICME and performed a series of three-dimensional magnetohydrodynamic (MHD) simulations with different sets of ICME parameters. The ICME is injected into the background solar wind generated from near-Sun data and interplanetary scintillation (IPS) data via an MHD-IPS tomography method. We will compare simulation results to in situ observations near the Earth and discuss how the physical properties of an ICME affect the space weather disturbances at 1 AU.

• Kyungpook Mathematical Journal
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• 제51권3호
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• pp.311-322
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• 2011

In this paper, we generalize the definition of a closure operator for a finite matroid to a pi-space and obtain the corresponding closure axioms. Then we discuss some properties of pi-spaces using the closure axioms and prove the non-existence for the dual of a pi-space. We also present some results on the automorphism group of a pi-space.

• 대한수학회논문집
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• 제16권2호
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• pp.277-285
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• 2001

The purpose of this paper is to give a proof of a generalized convex-valued selection theorem which is given by weakening a Banach space to a completely metrizable locally convex topological vector space, i.e., a Frechet space. We also develop the properties of upper semi-continuous singlevalued mapping to those of upper semi-continuous multivalued mappings. These properties wil be applied in our further consideraations of selection theorems.

• Korean Journal of Mathematics
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• 제11권2호
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• pp.85-91
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• 2003

On the setting of the upper half-space of the euclidean space $\mathbf{R}^n$, we show some properties of weighted harmonic Bergman functions.

• 충청수학회지
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• 제12권1호
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• pp.23-31
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• 1999

The purpose of the present paper is devoted to a study of some properties on spaces with a quartic metric from the standpoint of Finsler geometry.

• 천문학회보
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• 제38권1호
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• pp.40.2-40.2
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• 2013

The properties of bright galaxies are closely related to those of their nearby neighbors and satellite galaxies. In addition, the properties of galaxies in clusters are known to be strongly affected by the cluster environment. These two environmental effects raise a question: how significantly do nearby neighbors and satellite galaxies affect the properties of bright galaxies in a cluster? To address this issue, we reduce and analyze the deep and wide-field images of Abell 3659 (z ~ 0.0907) in the g' and r' bands obtained using IMACS on the Magellan (Baade) 6.5m telescope. The main goal of this study is to find out the relationship between the properties of bright galaxies and those of fainter companion galaxies in a cluster. This poster is a progress report, in which we present the sample selection and the preliminary results.

• 대한수학회지
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• 제42권5호
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• pp.1017-1030
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• 2005

In this paper, we study averaging properties in Banach spaces using the Brunel-Sucheston's spreading model. We show that the Schlumprecht space S does not have the Banach­Saks property and II is finitely representable in the Schlumprecht space S using the spreading model properties.

• Journal of Astronomy and Space Sciences
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• 제8권1호
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• pp.1-10
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• 1991

The dust formation processes in novae are investigated with close attention to recent infrared observations. Using mainly the classical nucleation theory, we have calculated the time scales of dust formation and growth in the environments of novas. Those time scales roughly the typical observations. We have classified the dust-forming novae into three classes according to their explosion properties and the thermodynamic properties of dust grains. Oxygen grains form much later than carbon grains because of their thermodynamic properties. The effect of grain formation to the efficiency of stellar winds to drive the material outward is tested with newly obtained Planck mean values of dust grains.

• 충청수학회지
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• 제31권4호
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• pp.461-466
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• 2018

$Let\;f:X{\rightarrow}X$ be a continuous surjection of a compact metric space X and let ${\sigma}_f:X_f{\rightarrow}X_f$ be the shift map on the inverse limit space $X_f$ constructed by f. We show that if a continuous surjective map f has some shadowing properties: the asymptotic average shadowing property, the average shadowing property, the two side limit shadowing property, then ${\sigma}_f$ also has the same properties.