• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3413-3430
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• 2017

With the fast increasing popularity of mobile services, ubiquitous mobile devices with enhanced sensing capabilities collect and share local information towards a common goal. The recent Mobile Crowd Sensing (MCS) paradigm enables a broad range of mobile applications and undoubtedly revolutionizes many sectors of our life. A critical challenge for the MCS paradigm is to induce mobile devices to be workers providing sensing services. In this study, we examine the problem of sensing task assignment to maximize the overall performance in MCS system while ensuring reciprocal advantages among mobile devices. Based on the overlapping coalition game model, we propose a novel workload determination scheme for each individual device. The proposed scheme can effectively decompose the complex optimization problem and obtains an effective solution using the interactive learning process. Finally, we have conducted extensive simulations, and the results demonstrate that the proposed scheme achieves a fair tradeoff solution between the MCS performance and the profit of individual devices.

• IE interfaces
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• v.13 no.4
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• pp.556-563
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• 2000

In this paper, we consider wavelength assignment problem (WAP) in Wavelength division multiplexed (WDM) unidirectional optical telecommunication ring networks. We show that, even though WAP on unidirectional ring belongs to NP-hard, WAP can be exactly solvable in real-sized WDM rings for near future demand. To accomplish this, we convert WAP to the vertex coloring problem of the related graph and choose a special integer programming formulation for the vertex coloring problem. We use a column generation technique in a branch-and-price framework for the suggested formulation. We also propose some generic heuristics and do the performance comparison with the suggested optimization algorithm.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.65
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• pp.89-102
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• 2001

In this paper, the aircraft route scheduling consists of two steps; the pairing generation and the aircraft assignment. The pairing generation is heuristic approach how flights construct pairings from and to the main base. The aircraft resource assignment which is to establish a aircraft route schedule is constructed by constraint satisfaction problem technique. ILOG solver and schedule is used to solve this problem. In addition, a aircraft route reschedule process against departure-arrival delay or aircraft maintenance schedule change is added by partial constraints satisfaction problem technique. Also, Gantt chart made by ILOG views is used to show aircraft route schedule results more easily.

• Journal of the military operations research society of Korea
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• v.36 no.3
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• pp.29-42
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• 2010

In this study, the weapon-target assignment problem arising in military application of operations research is considered. We reformulated the problem in order to simplify the solution methods based on genetic algorithms and heuristics. Since the problem is well known as NP-complete and cannot be solved in polynomial time, such solution methods have been widely used to obtain good solutions. Two chromosome representations--target number representation and permutation representation--in genetic algorithm are compared. In addition, a construction heuristic and three improving heuristics are developed. Several experiments under the condition of transitivity rules in weapon's kill probability have been accomplished. It shows that the construction heuristic and exchange-based improving heuristic guarantees good solutions within a second and the performance of construction heuristic is sensitive to transitivity rules.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.260-267
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• 2017

Quantum-inspired Genetic Algorithm (QGA) is a probabilistic search optimization method combined quantum computation and genetic algorithm. In QGA, the chromosomes are encoded by qubits and are updated by quantum rotation gates, which can achieve a genetic search. Asset-based weapon target assignment (WTA) problem can be described as an optimization problem in which the defenders assign the weapons to hostile targets in order to maximize the value of a group of surviving assets threatened by the targets. It has already been proven that the WTA problem is NP-complete. In this study, we propose a QGA and a hybrid-QGA to solve an asset-based WTA problem. In the proposed QGA, a set of probabilistic superposition of qubits are coded and collapsed into a target number. Q-gate updating strategy is also used for search guidance. The hybrid-QGA is generated by incorporating both the random search capability of QGA and the evolution capability of genetic algorithm (GA). To observe the performance of each algorithm, we construct three synthetic WTA problems and check how each algorithm works on them. Simulation results show that all of the algorithm have good quality of solutions. Since the difference among mean resulting value is within 2%, we run the nonparametric pairwise Wilcoxon rank sum test for testing the equality of the means among the results. The Wilcoxon test reveals that GA has better quality than the others. In contrast, the simulation results indicate that hybrid-QGA and QGA is much faster than GA for the production of the same number of generations.

• 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.

• 대한공업교육학회지
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• v.42 no.1
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• pp.87-105
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• 2017

The purpose of this study was to verify that students' interest in team activities for problem solving, the effect of interest on it, and students' changes in perceptions and their behavioral characteristics in the process of problem solving. The study reviewed documents prepared by students, such as work sheets, descriptive questionnaires, works and their photos, student activity photos and observation journals of teachers. The results of this research are as below. First, a problem solving team activity for making a model car was considered an interesting assignment by more than 90% of male/female students. The fact that female students could be more focused on this assignment than male students was discovered. Interest in the assignment not only had an influence on the points from the start (the blueprint) to the end (model cars completed based upon the designs) of problem solving, but also provided the traction power behind the assignment. Second, the problem solving team activity allowed the students to change their existing recognition (thoughts) while positively taking a lead or indirectly utilizing various learning experiences (including experiences of failure). Third, $2^{nd}$ graders in middle school had a tendency to solve problems in dependently rather than to receive help from others when they encountered problematic situations.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.111-117
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• 2004

In distributed-computing environments, there is a strong demand for the authentication and the access control of distributed-shared resources. I have presented role-based access control (RBAC) concept that is in the spotlight recently. RBAC model shows the standardized access control of complicated organization's resources. In RBAC, senior role has junior role's permission by virtue of role hierarchy. But, junior role cannot perform the permission, which is granted to the senior or other role groups. Inheritances of permissions in role hierarchies are static. In order to tackle this problem, I propose a dynamic role assignment, which classified into passive role assignment and active role assignment, and design dynamic role assignment protocol and implement role assignment server.

• The Journal of Society for e-Business Studies
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• v.12 no.3
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• pp.235-249
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• 2007

Workflow systems are software systems that control the execution of long-term processes. Members of an organization are in charge of executing processes. A work assignment policy, i.e who should perform a certain piece of process, has to be modeled and implemented in workflow systems. Organizations may have a large variety of problems in work assignment, and it may not be feasible to devise a single model to cover all problems. In this paper, we introduce generality to work assignment design problems in workflow systems We provide a meta-model based approach which enables us to define arbitrary problem oriented work assignment policies.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.532-534
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• 1990

We suggest a new energy function that improves the area complexity of the Hopfield Crossbar Network. Through converting data representation to an encoded format, we reduce the number of nodes of the network, and thus reduce the entire size. We apply this approach to the layer assignment problem, and use the modified delayed self-feedback Hopfield Network. Area complexity of the existing network for layer assignment ploblem is improved from O( $N^2L^2$ ) to O($N^2$(log L)$^2$).