• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.138-141
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• 2006

This paper considers a two-machine flow-shop scheduling problem for minimizing mean flow time. Each job has three non-preemptive operations, where the first and third operations must be Processed on the first and second machines, respectively, but the second operation can be processed on either machine. A lower bound based on SPT rule is derived, which is then used to develop a branch-and-bound algorithm. Also, an efficient simple heuristic algorithm is developed to generate a near-optimal schedule. Numerical experiments are performed to evaluate the performances of the proposed branch-and-bound and the heuristic algorithm

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.188-193
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• 2009

본 논문은 조립과 분리시스템이 혼합된 Fork-and-Join 시스템에서의 일정계획문제를 고려하고 있다. 최초 단계에서는 구성품단위로 분리가 발생하고 두 번째 단계에서는 부품생산단계에서 각 부품 또는 구성품이 서로 다른 설비와 경로를 통해 독립적으로 생산된 후 최종 조립단계로 이동하게 되고, 그곳에서 조립공정을 통해 제품으로 완성된다. 본 논문에서는 이러한 Fork-and-Join 시스템에서 최종완료시간(makespan)을 최소화 할 수 있는 발견적 해법을 제안하고 이 해법의 최악오차한계(worst-case error bound)가 2라는 것을 증명한다. 또한, 제안된 문제의 효과적인 3가지 하한값(lower bound)을 제시하고 다양한 수치실험을 통해 제안된 발견적 해법의 결과와 하한값과의 비교를 통해 제안된 해법이 성능이 우수함을 증명한다.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.2
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• pp.213-220
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• 2007

This paper considers a two-stage hybrid flow shop scheduling problem for the objective of minimizing the number of tardy jobs. Each job is processed through the two production stages in stages, each of which has multiple identical parallel machines. The problem is to determine the allocation and sequence of jobs at each stage. A branch and bound algorithm that gives the optimal solutions is suggested that incorporates the methods to obtain the lower and upper bounds. Dominance properties are also suggested to reduce the search space. To show the performance of the algorithm, computational experiments are done on randomly generated problems, and the results are reported.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.84-87
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• 2006

Batch binding experiments were performed to assess the recovery performance of glyceraldehyde 3-phosphate dehydrogenase (G3PDH) bound to the unshielded and polymer (polyvinyl pyrrolidone. PVP)-shielded dye-ligand (Cibacron Blue 3GA) adsorbent. The adoption of a polymer-shielded, dye-ligand technique facilitated the elution efficiency of bound G3PDH. It was demonstrated that the recovery of G3PDH using polymer-shielded dye-ligand adsorption yielded higher elution efficiency, at 60.5% and a specific activity of 42.3 IU/mg, after a low ionic strength elution (0.15 M NaCl). The unshielded dye-ligand yielded lower elution efficiency. at 6.5% and a specific activity of 10.2 IU/mg.

• The Korean Journal of Food And Nutrition
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• v.9 no.2
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• pp.137-142
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• 1996

To develop antioxidant substances in plant, phenolic compounds in Bangah (Igodon japonicus, Hara) and antioxidative effects of cell extracts were investigated. Defatted samples of Bangah were extracted with acetone/methanol and the extracts were fractionated Into the free and bound types of phenolics. The equal amounts of fractions were dissolved In soybean oil and autoxidized at 45$^{\circ}C$ for 25 days. Peroxide value and TBA values were determined every 5 days during oxidation. Changes of peroxide and TBA values showed antioxidant effects, which were lower than control during the oxidation periods. The effects of cell extracts were evaluated as high as BHT, 0.02 ppm. The antioxidative effect of insoluble-bound phenolic extract was higher than that of free. The contents of phenolic compounds in insoluble-bound fraction were also higher than free fraction.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.4
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• pp.63-71
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• 2003

This paper analyses a deterministic scheduling problem concerned with manufacturing multiple types of components at a pre-assembly stage composed of parallel fabrication machines. Each component part is machined on a fabrication machine specified in advance. The manufactured components are subsequently assembled into products. The completion time of a job(product) is measured by the latest completion time of its all components at the pre-assembly stage. The problem has the objective measure of minimizing the total weighted completion time of a finite number of jobs. Two lower bounds are derived and tested in a branch-and-bound scheme. Also, three constructive heuristic algorithms are developed based on the machine aggregation and greedy strategies. Some empirical evaluation of the performance of the proposed branch-and-bound and heuristic algorithms are also performed.

• Elastomers and Composites
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• v.33 no.1
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• pp.44-51
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• 1998

The purpose of this experiments were investigated on the physical properties of rubber com-pounds containing two types carbon black. Bound rubber and interaction coefficient for com-pounds with pure carbon black were higher than those for the compounds with dual phase carbon black. Slightly higher values in 300% modulus and tensile strength indicated that the ratio of rubber-filler bound to rubber-rubber bound of pure carbon black were higher than those of com-pounds with dual phase carbon black. It was founded that dynamic properties, that is rebound, heat build-up, 0 & $60^{\circ}C$ tan $\delta$, and cut and chip loss of compounds with dual phase carbon black were better than those of compounds with pure carbon black, but abrasion property of dual phase carbon black was lower than those of pure carbon black because of low reinforcing ability.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.4
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• pp.34-42
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• 2006

This paper considers an assembly-type flowshop scheduling problem in which each job is assembled with two types of components. One type of the components is outsourced with positive lead time but the other type is fabricated in-house at the first stage. The two types of the components should be prepared at the first stage before starting the assembly operation for each job at the second stage. The objective is to schedule the jobs so that the makespan is minimized. Some solution properties and lower bounds are derived and incorporated into a branch and bound algorithm. Also, an efficient heuristic is developed. The performances of the proposed branch and bound algorithm and heuristic are evaluated through computational experiments.

• International journal of advanced smart convergence
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• v.7 no.4
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• pp.19-26
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• 2018

One of the distinct features of Wireless Sensor Networks (WSNs) is duty cycling mechanism, which is used to conserve energy and extend the network lifetime. Large duty cycle interval introduces lower energy consumption, meanwhile longer end-to-end (E2E) delay. In this paper, we introduce an energy consumption minimization problem for duty-cycled WSNs. We have applied Q-learning algorithm to obtain the maximum duty cycle interval which supports various delay requirements and given Delay Success ratio (DSR) i.e. the required probability of packets arriving at the sink before given delay bound. Our approach only requires sink to compute Q-leaning which makes it practical to implement. Nodes in the different group have the different duty cycle interval in our proposed method and nodes don't need to know the information of the neighboring node. Performance metrics show that our proposed scheme outperforms existing algorithms in terms of energy efficiency while assuring the required delay bound and DSR.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.86-102
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• 1991

The purpose of this paper is to present a branch and bound algorithm for the hierarchical transportation network design problem in 2-level directed networks. This problem is to find the least cost of hierarchical transportation networks which consist of a primary path and a secondary path. The primary path is a simple path from a prespecified orgin node to a prespecified terminal node. All nodes must be either a transsipment node on the primary path or connected to that path via secondary arcs. This problem is formulated to a 0-1 inter programming problem with assignment and illegal subtour elimination equations as constaints. We show that the subproblem relaxing subtour elimination constraints is transformed to a linear programming problem by means of the totally unimodularity. Optimal solutions of this subproblem are polynoially obtained by the assignment algorithm and complementary slackness conditions. Therefore, the optimal value of this subproblme is used as a lower bound. When an optimal solution of the subproblem has an illegal subtour, a better disjoint rule is adopted as the branching strategy for reducing the number of branched problems. The computational comparison between the least bound rule and the depth first rule for the search strategy is given.