• Nuclear Engineering and Technology
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• 제24권1호
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• pp.14-29
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• 1992

원자력 발전소에서 발생하는 공통원인 고장을 분석하기 위한 컴퓨터 코드 COMCAF를 개발하였다. 공통원인 고장을 다룰 때, 먼저 계통의 최소 단절집합들을 공통원인 기본사상들이 고려되지 않은 고장수목으로부터 구한다. 그리고, 공통원인 고장들이 같은 최소 단절집합내의 부품들간에 있는지 또는 서로 다른 최소 단절집합들의 부품들간에 있는지를 고려하여 이들 최소 단절집합들의 발생 확률값을 계산한다. 유사하거나 동일한 부품들간에 공통원인 고장이 있을때는 Basic Para-meter 모델을 사용한다. 그러나, 서로 다른 부품들간에 공통원인 고장이 있을때는 Basic Para-meter모델에 쓰인 Symmetry Assumption을 두개 이상의 부품에 영향을 주는 기본사상들에만 적용한다. Inclusion-Exclusion방법을 사용하여 정점사상확률간을 구한다. 이 경우 같은 최소 단절 집합들에 있는 부품들의 공통원인 고장뿐만아니라 서로 다른 최소 단절집합들에 있는 부품들의 공통원인 고장도 쉽게 고려될 수 있다. 본 연구에서는 이러한 공통원인 고장분석을 가압경수로의 보조 급수계통에 적용하였다. 이들 정점사상의 확률값들을 공통원인 고장이 없는 경우와 비교하였다.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 1999년도 추계학술대회-지능형 정보기술과 미래조직 Information Technology and Future Organization
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• pp.347-354
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• 1999

The credit rating represents an assessment of the relative level of risk associated with the timely payments required by the debt obligation. In this paper, we present a new approach to credit rating of customers based on the rough set theory. The concept of a rough set appeared to be an effective tool for the analysis of customer information systems representing knowledge gained by experience. The customer information system describes a set of customers by a set of multi-valued attributes, called condition attributes. The customers are classified into groups of risk subject to an expert's opinion, called decision attribute. A natural problem of knowledge analysis consists then in discovering relationships, in terms of decision rules, between description of customers by condition attributes and particular decisions. The rough set approach enables one to discover minimal subsets of condition attributes ensuring an acceptable quality of classification of the customers analyzed and to derive decision rules from the customer information system which can be used to support decisions about rating new customers. Using the rough set approach one analyses only facts hidden in data, it does not need any additional information about data and does not correct inconsistencies manifested in data; instead, rules produced are categorized into certain and possible. A real problem of the evaluation of the evaluation of credit rating by a department store is studied using the rough set approach.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제5권2호
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• pp.149-155
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• 1998

In this paper, we construct the minimal set of generators which generate the subgroup T of the Weyl group of Kac-Moody algebra.

• Korean Journal of Mathematics
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• 제22권3호
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• pp.583-590
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• 2014

In this paper we give some relationships between quasi-Ellis groups and some subgroups of the automorphism group. In particular, we investigate several characterizations on some subgroups of the automorphism group.

• 충청수학회지
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• 제27권4호
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• pp.563-569
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• 2014

We investigate a minimal set of generators of a homogeneous ideal of a curve of degree d on a linearly normal smooth surface scroll W in $P^r$ whose arithmetic genus is maximal among curves of degree d on W.

• 대한수학회논문집
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• 제15권3호
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• pp.549-553
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• 2000

For a continuous map of the circle to itself, we give necessary and sufficient conditions for the $\omega$-limit set of each nonwandering point to be minimal.

• Journal of Information Processing Systems
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• 제6권2호
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• pp.197-208
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• 2010

Test scenarios can be derived based on some system models for requirements validation purposes. Model-based test suite reduction aims to provide a smaller set of test scenarios which can preserve the original test coverage with respect to some testing criteria. We are proposing to apply Formal Concept Analysis (FCA) in analyzing the association between a set of test scenarios and a set of transitions specified in a state machine model. By utilizing the properties of concept lattice, we are able to determine incrementally a minimal set of test scenarios with adequate test coverage.

• 경영과학
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• 제23권1호
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• pp.75-85
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• 2006

The rectilinear Steiner tree problem (RSTP) is to find a minimum-length rectilinear interconnection of a set of terminals in the plane. It is well known that the solution to this problem will be the minimal spanning tree(MST) on some set Steiner points. The RSTP is known to be NP-complete. The RSTP has received a lot of attention in the literature and heuristic and optimal algorithms have been proposed. A key performance measure of the algorithm for the RSTP is the reduction rate that is achieved by the difference between the objective value of the RSTP and that of the MST without Steiner points. A hybrid evolutionary strategy on RSTP based upon nodes set is presented. The computational results show that the hybrid evolutionary strategy is better than the previously proposed other heuristic. The average reduction rate of solutions from the evolutionary strategy is about 11.14%, which is almost similar to that of optimal solutions.

• 대한수학회지
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• 제42권3호
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• pp.573-597
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• 2005

A continuous linear operator T, on the space of entire functions in d variables, is PDE-preserving for a given set $\mathbb{P}\;\subseteq\;\mathbb{C}|\xi_{1},\ldots,\xi_{d}|$ of polynomials if it maps every kernel-set ker P(D), $P\;{\in}\;\mathbb{P}$, invariantly. It is clear that the set $\mathbb{O}({\mathbb{P}})$ of PDE-preserving operators for $\mathbb{P}$ forms an algebra under composition. We study and link properties and structures on the operator side $\mathbb{O}({\mathbb{P}})$ versus the corresponding family $\mathbb{P}$ of polynomials. For our purposes, we introduce notions such as the PDE-preserving hull and basic sets for a given set $\mathbb{P}$ which, roughly, is the largest, respectively a minimal, collection of polynomials that generate all the PDE-preserving operators for $\mathbb{P}$. We also describe PDE-preserving operators via a kernel theorem. We apply Hilbert's Nullstellensatz.

• 대한수학회논문집
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• 제34권3호
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• pp.991-1004
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• 2019

Firstly we consider preorders (not necessarily partial orders) on a canonical quotient of the set of the homotopy classes of continuous maps between two spaces induced by a certain equivalence relation ${\sim}_{{\varepsilon}R}$. Secondly we apply it to a classification of orientable fibrations over Y with fibre X. In the classification theorem of J. Stasheff [22] and G. Allaud [3], they use the set $[Y,\;Baut_1X]$ of homotopy classes of continuous maps from Y to $Baut_1X$, which is the classifying space for fibrations with fibre X due to A. Dold and R. Lashof [11]. In this paper we give a classification of fibrations using a preordered set (abbr., proset) structure induced by $[Y,\;Baut_1X]_{{\varepsilon}R}:=[Y,\;Baut_1X]/{\sim}_{{\varepsilon}R}$.