• Honam Mathematical Journal
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• v.31 no.3
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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.

• Honam Mathematical Journal
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• v.31 no.3
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• pp.267-278
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• 2009

As a survey-type article, the paper reviews the recent results on a (generalized) universal covering space in digital covering theory. The recent paper [19] established the generalized universal (2, k)-covering property which improves the universal (2, k)-covering property of [3]. In algebraic topology it is well-known that a simply connected and locally path connected covering space is a universal covering space. Unlike this property, in digital covering theory we can propose that a generalized universal covering space has its intrinsic feature. This property can be useful in classifying digital covering spaces and in studying a shortest k-path problem in data structure.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.4
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• pp.328-336
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• 2001

In this paper, an approach is presented for determining the required storage capacity of a warehouse with leased public space. Storage assignment policies considered are randomized and class-based storage assignment policies. An analytic model for each of the storage policies is formulated with the objective of minimizing the cost of owned storage space and leased space while satisfying a desired service level of protection against space shortages. Cost functions used in the models are piecewise liear with fixed costs. For the models, algorithms are developed to generate optimal solutions. The approach is applied to the systems where the standard economic-order-quantity inventory model is used for all items being stored in the warehouse.

• Journal of the Korean Mathematical Society
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• v.43 no.1
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• pp.147-157
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• 2006

In this paper, we study complete maximal space-like hypersurfaces with constant Gauss-Kronecker curvature in an antide Sitter space $H_1^4(-1)$. It is proved that complete maximal spacelike hypersurfaces with constant Gauss-Kronecker curvature in an anti-de Sitter space $H_1^4(-1)$ are isometric to the hyperbolic cylinder $H^2(c1){\times}H^1(c2)$ with S = 3 or they satisfy $S{\leq}2$, where S denotes the squared norm of the second fundamental form.

• Communications of the Korean Mathematical Society
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• v.27 no.4
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• pp.771-780
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• 2012

We study biminimal curves in 2-dimensional Riemannian manifolds of constant curvature.

• Journal of applied mathematics & informatics
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• v.30 no.3_4
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• pp.685-691
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• 2012

We define and characterize a somewhat fuzzy precontinuous mapping and a somewhat fuzzy preopen mapping on a fuzzy topological space. Besides, some interesting properties of those mappings are given.

• Journal of applied mathematics & informatics
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• v.32 no.1_2
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• pp.203-209
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• 2014

We define and characterize a somewhat fuzzy ${\gamma}$-irresolute continuous mapping and a somewhat fuzzy irresolute ${\gamma}$-open mapping on a fuzzy topological space.

• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.197-203
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• 2006

This paper addresses dynamic modeling and task-space trajectory following issues for nonholonomic mobile manipulators moving on a slope. An integrated dynamic modeling method is proposed considering nonholonomic constraints and interactive motions. An adaptive neural-fuzzy controller is presented for end-effector trajectory following, which does not rely on precise apriori knowledge of dynamic parameters and can suppress bounded external disturbances. Effectiveness of the proposed algorithm is verified through simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.18-23
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• 1993

In this paper, we attempt to estimate the state of a finite state system. In such system, we can observe time series data which has some significant behaviors corresponding to its system states. The behavior is characterized by feature parameters extracted from time series. Our thought is that the system output time series data is expressed as a sequence of behavior patterns which are represented by clusters in feature parameters space. An algorithm jointing fuzzy clustering to fuzzy finite state transition model is suggested.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.395-398
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• 2005

유비쿼터스 공간 내에서 사용자의 상황을 파악하고 적합한 서비스를 제공하기 위해서는 상황을 정확하게 이해하는 것이 필요하다. 따라서 본 논문에서는 홈 네트워크에 접속한 센서나 기기를 사용하여 환경이나 상황의 변화에 따른 적합한 서비스를 제공받을 수 있는 방법을 제안한다.