• Journal of the Chungcheong Mathematical Society
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• v.23 no.3
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• pp.481-486
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• 2010

In this paper, we introduce the concepts of strongly c-convex( strongly c-concave) function, almost c-convex function on preconvex spaces. We investigate the relationships between such concepts and several types of preconvex sets.

• Bulletin of the Korean Mathematical Society
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• v.58 no.4
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• pp.877-884
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• 2021

We prove that if a compact convex hypersurface of ℝⁿ⁺¹ has almost maximal extinction time when it is evolved by the mean curvature flow, then it must be nearly round in the C⁰-norm.

• Journal of the Korean Mathematical Society
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• v.41 no.4
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• pp.737-746
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• 2004

In this paper, from the KKM theorem, we deduce almost fixed point theorems for convex-valued u.s.c. (or l.s.c.) multimaps satisfying certain conditions originated from Zima [19]. From these results, we obtain various fixed point theorems which extend a number of known results.

• Journal of the Korean Mathematical Society
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• v.45 no.1
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• pp.1-27
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• 2008

We introduce a new concept of convex spaces and a multimap class K having certain KKM property. From a basic KKM type theorem for a K-map defined on an convex space without any topology, we deduce ten equivalent formulations of the theorem. As applications of the equivalents, in the frame of convex topological spaces, we obtain Fan-Browder type fixed point theorems, almost fixed point theorems for multimaps, mutual relations between the map classes K and B, variational inequalities, the von Neumann type minimax theorems, and the Nash equilibrium theorems.

• Journal of the Korean Mathematical Society
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• v.31 no.3
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• pp.417-427
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• 1994

Let C be a nonempty closed bounded convex subset of a real Banach space X.

• Communications of the Korean Mathematical Society
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• v.34 no.4
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• pp.1279-1287
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• 2019

The main purpose of the paper is to prove that if a compact Riemannian manifold admits a gradient ${\rho}$-Einstein soliton such that the gradient Einstein potential is a non-trivial conformal vector field, then the manifold is isometric to the Euclidean sphere. We have showed that a Riemannian manifold satisfying gradient ${\rho}$-Einstein soliton with convex Einstein potential possesses non-negative scalar curvature. We have also deduced a sufficient condition for a Riemannian manifold to be compact which satisfies almost ${\eta}$-Ricci soliton.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.259-264
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• 2000

The functions of the plug valve are the control of flow rate as well closing and opening pipe lines. Analyses on the flow characteristics in plug valve port are required to improve the performance and safety at severe operating conditions such as high-pressure and high-temperature. In this study, numerical analyses are carried out with varying the opening rate (fraction of the full open to close) of the valve and the shapes of valve Uk: straight, convex, concave and mixed shapes. The parameters influencing the flow characteristics in the valve are the discharge coefficient( $C_v$) and the resistance coefficient( K). Therefore, the distributions of static pressure, velocity vector and stream lines are investigated, and $C_v$ and K are calculated in each opening rate and shape. In case of full open, the static pressure passed through the valve port has almost been recovered. However, in case of other opening rates, the pressure does not permanently regained due to pressure drop leading to loss. This phenomenon in each shape of the valve shows the different behaviors. Calculation results show that the mixed shape has the best flow attribute.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.373-378
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• 2000

An experimental investigation on the incipience of nucleate boiling in forced flow of water is performed as a verification and extension of previous analysis. The effects of the subcooling, Reynolds number and surface curvature on the onset of nucleate boiling(ONB) in a concentric annulus flow channel with smooth inner heating surface is investigated experimentaly. Through flow visualization, the boiling phenomenon was observed directly and the experimental results were examined to find ONB heat flux. The results show that the variation of heat flux at ONB is increased linearly as the Reynolds number and subcooling are increased. The effect of surface curvature is very great specially for a small radius when radius of the inner heating tube is increased, the heat flux at ONB is almost inversely increased for the range of this investigation. It is found that the effect of convex surface curvature on ONB heat flux is very significant for a small radius.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3C
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• pp.288-296
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• 2009

In POCS (projection onto convex sets)-based reconstruction of HR (high resolution) image, the quality of reconstructed image is gradually improved through iterative motion estimation and image restoration. The amount of computation, however, increases because of the repeated inter-frame motion estimation. In this paper, an HR reconstruction algorithm is proposed where modified ARPS (adaptive rood pattern search) and POCS are simultaneously performed. In the modified ARPS, the motion estimates obtained from phase correlation or from the previous steps in POCS restoration are utilized as the initial reference in the motion estimation. Moreover, estimated motion is regularized with reference to the neighboring blocks' motion to enhance the reliability. Computer simulation results show that, when compared to conventional methods which are composed of full search block matching and POCS restoration, the proposed method is about 30 times faster and yet produces HR images of almost equal or better quality.

• Journal of Mushroom
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• v.6 no.3_4
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• pp.115-120
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• 2008

A new commercial strain 'Garlmoe' was developed by crossing monokaryons from selected wild strains. The optimal temperature of mycelial growth was $25^{\circ}C$ but it needed to adjust to $16{\sim}18^{\circ}C$ when incubated at the bottle cultivation. The optimal temperatures of fruiting body initiation and development were almost same to others like as $14^{\circ}C$ and $7{\sim}10^{\circ}C$, respectively. The color of 'Garlmoe' was typical to wild winter mushroom, that is, pileus was brown and lower part of stipe was dark brown. The surface on pileus of 'Garlmoe' was sticky 'Garlmoe' was a good commercial strain with high quality and high productivity characterized as quite even budding habit, straight and strong stipes and convex type pilei. The taste of this variety was very excellent because of better chewing feeling than white ones.