• Journal of applied mathematics & informatics
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• 제19권1_2호
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• pp.105-125
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• 2005

Motivated by the field experimental designs in agriculture, the theory of block designs has been applied to several areas such as statistics, combinatorics, communication networks, distributed systems, cryptography, etc. An explicit formula and its fast computational algorithm for a class of symmetric balanced incomplete block designs are presented. Based on the formula and the careful investigation of the modulus multiplication table, the algorithm is developed. The computational costs of the algorithm is superior to those of the conventional ones.

• 대한수학회지
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• 제45권5호
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• pp.1243-1253
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• 2008

In this paper, we construct one-factorizations of given complete graphs of even order. These constructions partition the edges of the complete graph into one-factors and triples. Our new constructions of one-factors and triples can be applied to a recursive construction of Steiner triple systems for all possible orders ${\geq}$15.

• 한국수학교육학회지시리즈A:수학교육
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• 제45권1호
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• pp.123-138
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• 2006

In this paper, we confirm through surveys and interviews that it helps students in solving a problem counting the number of combinations to find a structural isomorphism between the given problem and a typical problem with the same mathematical structure. Then we suggest that a problem of distributing balls into boxes might be a good candidate for a typical problem. This approach is coherent to the viewpoint given by English(2004) that it is educationally important to see the connection and relationship between problems with different context but with similar mathematical structure.

• 한국초등수학교육학회지
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• 제21권2호
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• pp.365-389
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• 2017

본 연구에서는 초등 영재학생들의 원순열 과제 해결 과정을 분석하여 교수학적 시사점을 도출하는 데 목적을 두었다. 구체적으로, 본 연구에서는 초등 영재학생들에게 원순열 과제를 제공하여 이 학생들의 해결 과정을 표현, 세기 과정, 결과 집합구성 방식을 통하여 분석하였다. 연구 결과 원순열 과제를 해결하는 과정에서 일부 학생들이 유추를 활용하는 장면이 확인되었으며, 학생들은 가능한 결과들의 범주화와 재범주화 과정에서, 그리고 유추의 적절하지 않은 활용으로 인하여 원순열 과제해결에 어려움을 겪는 것으로 확인되었다.

• 한국수학사학회지
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• 제19권1호
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• pp.33-42
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• 2006

본 논문은 조합론 분야에서 매우 중요하게 다루는 조합대상들의 동형문제에 관한 이론적 배경의 연구와 아울러 역사적 배경을 고찰해본다. 또한, 유한체에서 케일리대상들의 동형사상 문제에 대한 부분적인 결과를 소개한다.

• International Journal of Precision Engineering and Manufacturing
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• 제8권1호
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• pp.21-26
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• 2007

In industry, multihead automatic combination weighers are used to provide accurate weights at high speed. To minimize giveaway, greater accuracy is desired, especially for valuable products. This paper describes a combination algorithm based on bit operation. The combination method is simple and saves time, since only the elements to be considered for combination are generated. The total number of combinations from which the desired output weight is chosen can be increased by extending the combination from memory hoppers to include some weighing hoppers. For an eight-channel weigher, three or four combination elements are best. In addition to targeting approximately equal amounts of products in each channel, this study investigated other schemes. Simulation results show that schemes targeting combination elements with an unequal distribution of the output weight are more accurate. The most accurate scheme involves supplying products to all memory and weighing hoppers before commencing the combination operation. However, this scheme takes more time.

• 산업공학
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• 제13권3호
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• pp.479-485
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• 2000

We consider a Location-Allocation Problem with the Cost of Land(LAPCL). LAPCL has extremely huge size of problem and complex characteristic of location and allocation problem. Heuristics and decomposition approaches on simple Location-Allocation Problem were well developed in last three decades. Recently, genetic algorithm(GA) is used widely at combinatorics and NLP fields. A lot of research shows that GA has efficiency for finding good solution. Our main motive of this research is developing of a package for LAPCL. We found that LAPCL could be reduced to trivial problem, if locations were given. In this case, we can calculate fitness function by simple technique. We built a database constructed by zipcode, latitude, longitude, administrative address and posted land price. This database enables any real field problem to be coded into a mathematical location problem. We developed a package for a class of multi-location problem at PC. The package allows for an interactive interface between user and computer so that user can generate various solutions easily.

• 대한수학회보
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• 제32권2호
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• pp.337-342
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• 1995

A semiring is a binary system $(S, +, \times)$ such that (S, +) is an Abelian monoid (identity 0), (S,x) is a monoid (identity 1), $\times$ distributes over +, 0 $\times s s \times 0 = 0$ for all s in S, and $1 \neq 0$. Usually S denotes the system and $\times$ is denoted by juxtaposition. If $(S,\times)$ is Abelian, then S is commutative. Thus all rings are semirings. Some examples of semirings which occur in combinatorics are Boolean algebra of subsets of a finite set (with addition being union and multiplication being intersection) and the nonnegative integers (with usual arithmetic). The concepts of matrix theory are defined over a semiring as over a field. Recently a number of authors have studied various problems of semiring matrix theory. In particular, Minc [4] has written an encyclopedic work on nonnegative matrices.

• 대한수학회지
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• 제34권1호
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• pp.181-193
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• 1997

The enumeration of various classes of paths in the real plane has an important implications in the area of combinatorics wit statistical applications. In 1887, D. Andre [3, pp. 21] first solved the famous ballot problem, formulated by Berttand [2], by using the well-known reflection principle which contributed tremendously to resolve the problems of enumeration of various classes of lattice paths in the plane. First, it is necessary to state the definition of NSEW-paths in the palne which will be employed throughout the paper. From [3, 10, 11], we can find results concerning many of the basics discussed in section 1 and 2.

• 한국국방경영분석학회지
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• 제25권2호
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• pp.117-129
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• 1999

We consider a Location-Allocation Problem with the Cost of Land(LAPCL). LAPCL has extremely huge size of problem and complex characteristic of location and allocation problem. Heuristics and decomposition approaches on simple Location-Allocation Problem were well developed in last three decades. Currently, genetic algorithm(GA) is used widely at combinatorics and NLP fields. A lot of research show that GA has efficiency for finding good solution. Our main motive of this research is developing of a GA in LAPCL. We found that LAPCL could be reduced to trivial problem, if locations were given. In this case, we can calculate fitness function by simple technique. We propose fourth alternative genetic algorithm. Computational experiments are carried out to find a best algorithm.