• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.71-77
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• 2019

This paper defines a multi-selection knapsack problem and presents an algorithm for seeking its optimal solution. Multi-selection means that all members of the particular group be selected or excluded. Our branch-and-bound algorithm introduces a simplex containing the feasible region of the original problem to exploit the fact that the most tightly underestimating function on the simplex is linear. In bounding operation, the subproblem defined over the candidate simplex is minimized. During the branching process the candidate simplex is splitted into two one-less dimensional subsimplices by being projected onto two hyperplanes. The approach of this paper can be applied to solving the global minimization problems under various types of the knapsack constraints.

• Proceedings of the Korea Database Society Conference
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• 1997.10a
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• pp.504-514
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• 1997

관계형 데이터베이스의 성능을 향상시키는데 중요한 요소 중의 하나는 트랜잭션을 처리하기 위해 데이터를 디스크에서 주기억장치로 옮기는데 필요한 디스크 액세스(access) 횟수이다. 본 연구는 관계형 데이터베이스에서 트랜잭션을 처리할 때, 릴레이션(relation)을 수직분할하여 디스크에 단편(fragment)으로 저장하므로써 필요한 단편만 액세스하여 액세스 횟수를 감소시키는데 목적이 있다. 단편에 속성을 중복할당하여 수직분할하므로써 트랜잭션을 만족시키는 단편의 수를 감소시켜 중복할당을 고려하지 않은 방법보다 디스크 액세스 횟수를 감소시킬 수 있다. 갱신트랜잭션의 경우 하나의 속성이 갱신되면 중복된 속성을 모두 갱신하여야 하므로 액세스 횟수가 증가하지만, 조회트랜잭션의 경우 각 단편에 속성을 중복할당하여 액세스 횟수를 감소시킬 수 있다. 본 연구에서는 속성의 중복을 허용하여 단편을 구성하는 경우에 중복을 고려하지 않은 경우를 포함하므로 효과적으로 디스크 액세스 횟수를 감소시킬 수 있다. 본 연구에서는 중복할당을 고려하여 디스크의 액세스 횟수를 최소화시킬 수 있는 수직분할문제의 0-1 정수계획모형을 개발하고, 모형에 대한 최적해법으로 분지한계법을 제안한다.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.2
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• pp.83-101
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• 1998

Assembly U-lines are increasingly accepted in industry, especially just-in-time production systems, for the efficient utilization of workforce. In this paper, we present an integer programming formulation and a branch-and-bound method for balancing the U-line with the objective of minimizing the number of workstations with a fixed cycle time. In the mathematical model, we provide the method that can reduce the number of variables and constraints. The proposed branch-and-bound method searches the optimal solution based on a depth-first-search. To efficiently search for the optimal solutions to the problems, an assignment rule is used in the method. Bounding strategies and dominance rules are also utilized. Some problems require a large amount of computation time to find the optimal solutions. For this reason. some heuristic fathoming rules are also proposed. Extensive experiments with test-bed problems in the literature are carried out to show the performance of the proposed method. The computational results show that our method is promising in solution quality.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.37
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• pp.241-249
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• 1996

In this paper, a 0-1 integer programming model for solving vertical partitioning problem minimizing the number of disk accesses is formulated and a branch-and-bound method is used to solve the binary vertical partitioning problem. In relational databases, the number of disk accesses depends on the amount of data transferred from disk to main memory for processing the transactions. Vertical partitioning of the relation can often result in a decrease in the number of disk accesses, since not all attributes in a tuple are required by each transactions. The algorithm is illustrated with numerical examples and is shown to be computationally efficient. Numerical experiments reveal that the proposed method is more effective in reducing access costs than the existing algorithms.

• Proceedings of the Korea Association of Information Systems Conference
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• 2004.11a
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• pp.409-416
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• 2004

동적 공급사슬망은 복잡하고 다양한 이해관계를 가진 기업들로 구성되어 있다. 다수의 구매자로부터 주문 의뢰가 동시다발적으로 발생하므로 하위 구성원들은 경쟁적 관계에 놓이게 된다. 그러므로 최적의 공급사슬구성을 위해서는 수평적 경쟁 관계를 고려하여 구성주체들간의 협력관계를 통해 이를 해결하여야 한다. 지금까지의 스케줄링 문제에서는 상위의 구성원이 하위 구성원들을 일방적으로 선택하는 의사결정이 이루어졌으나 본 문제에서는 구성원간의 협력관계에서 에이전트를 통한 다자간 협상을 통해 공급사슬 전체의 최적화를 구성하는 방법론을 제시한다. 본 협상방법론은 단일기계에서 상이한 납기일, 조기생산(earliness), 지연생산(tardiness)을 동시에 고려하였으며 전체 공급사슬의 평균절대편차(Mean Absolute Deviation)의 최소화를 목적으로 하고 있다. 본 협상방법론의 효과성을 증명하기 위해 분지한계법(Branch & Bound)과 비교하고, 알고리즘 구현을 통해 구매자 협상방법론의 최적화 여부를 실험을 통해 증명하였다.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.4
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• pp.567-578
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• 1996

In relational databases the number of disk accesses depends on the amount of data transferred from disk to main memory for processing the transactions. N-ary vertical partitioning of the relation can often result in a decrease in the number of disk accesses, since not all attributes in a tuple are required by each transactions. In this paper, a 0-1 integer programming model for solving n-ary vertical partitioning problem minimizing the number of disk accesses is formulated and a branch-and-bound method is used to solve it. A preprocessing procedure reducing the number of variables is presented. The algorithm is illustrated with numerical examples and is shown to be computationally efficient. Numerical experiments reveal that the proposed method is more effective in reducing access costs than the existing algorithms.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.3
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• pp.417-429
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• 1998

This paper considers two-sided (left and right side) assembly lines which are often used, especially in assembling large-sized products such as trucks and buses. A large number of exact algorithms and heuristics have been proposed to balance one-sided lines. However, little attention has been paid to balancing two-sided assembly lines. We present an efficient algorithm based on a branch and bound for balancing two-sided assembly lines. The algorithm involves a procedure for generating an enumeration tree. To efficiently search for the near optimal solutions to the problem, assignment rules are used in the method. New and existing bound strategies and dominance rules are else employed. The proposed algorithm can find a near optimal solution by enumerating feasible solutions partially. Extensive computational experiments are carried out to make the performance comparison between the proposed algorithm and existing ones. The computational results show that our algorithm is promising and robust in solution quality.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.1-8
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• 2002

A Branch-and-Cut algorithm is a branch-and-bound algorithm in which rutting planes are generated throughout the branch-and-bound tree. It is now one of the most widespread and successful methods for solving mixed integer programming problems. In this paper we presents efficient implementation techniques of branch-and-cut algorithm for miked integer programming problems.

• Journal of the Korea Computer Industry Society
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• v.5 no.3
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• pp.377-382
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• 2004

An unconstrained three-dimensional cutting problem describes the process of finding the cutting pattern that yields the maximum total profit-sum for the small parallelepipeds pieces cut from a large parallelepiped box and there is no limit to the number of pieces to be cut. The problem is a classic NP-hard. The bottom-up approach, which generates all of the feasible cutting patterns by combining two other cutting patterns, can be applied to the three-dimensional problem. We introduce a build and new branching strategies for the unconstrained three-dimensional cutting problem. The strategies are all generalized from the branching strategies proposed by G et at. to solve unconstrained two-dimensional cutting problems.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.755-760
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• 2010

In general, Lagrangian method for discrete optimization is a kind of technique to easily manage constraints. It is traditionally used for finding upper bounds in the branch-and-bound method. In this paper, we propose a new Lagrangian search method for the 0-1 knapsack problem with multiple constraints. A novel feature of the proposed method different from existing Lagrangian approaches is that it can find high-quality lower bounds, i.e., feasible solutions, efficiently based on a new property of Lagrangian vector. We show the performance improvement of the proposed Lagrangian method over existing ones through experiments on well-known large scale benchmark data.