Gabjin Yun
Myongji University
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Publication
Featured researches published by Gabjin Yun.
Bulletin of The Korean Mathematical Society | 2012
Jeongwook Chang; Seungsu Hwang; Gabjin Yun
In this paper, we deal with a critical point metric of the total scalar curvature on a compact manifold M. We prove that if the criti- cal point metric has parallel Ricci tensor, then the manifold is isometric to a standard sphere. Moreover, we show that if an n-dimensional Rie- mannian manifold is a warped product, or has harmonic curvature with non-parallel Ricci tensor, then it cannot be a critical point metric.
Fuzzy Sets and Systems | 2010
Gabjin Yun; Seungsu Hwang; Jeongwook Chang
In this paper, we introduce the notion of dilation and fuzzy Lipschitz of a map from a fuzzy metric space into a fuzzy metric space and we prove continuity properties for such maps. We also define the notion of the fuzzy Lipschitz distance between two fuzzy metric spaces and show that two compact fuzzy metric spaces whose Lipschitz distance is zero is fuzzy isometric to each other. On the other hand, we introduce the concept of minimal slope of a map between fuzzy metric spaces, which is defined by the ratio of two fuzzy metrics and derive some properties on it and relations with the dilation. In particular, we show that if the dilation of a map from a fuzzy metric space which is complete in George and Veeramani sense into itself is less than the minimal slope, then the map must have a fixed point. In case that a fuzzy metric space is considered in the sense of Kramosil and Michalek and that the completeness in the sense of Grabiec, the same result holds.
Pacific Journal of Mathematics | 2017
Gabjin Yun; Jinseok Co; Seungsu Hwang
On an
Bulletin of The Korean Mathematical Society | 2013
Jeong-Jin Kim; Gabjin Yun
n
Bulletin of The Korean Mathematical Society | 2009
Gabjin Yun; Dongho Kim
-dimensional complete manifold
Taiwanese Journal of Mathematics | 2014
Gabjin Yun; Jeongwook Chang; Seungsu Hwang
M
Mathematische Nachrichten | 2010
Seungsu Hwang; Jeongwook Chang; Gabjin Yun
, consider an
Taiwanese Journal of Mathematics | 2016
Gabjin Yun; Jeongwook Chang; Seungsu Hwang
h
General Relativity and Gravitation | 2016
Seungsu Hwang; Jeongwook Chang; Gabjin Yun
-almost gradient Ricci soliton, which is a generalization of a gradient Ricci soliton. We prove that if the manifold is Bach-flat and
Bulletin of The Korean Mathematical Society | 2016
Seungsu Hwang; Gabjin Yun
dh/du>0