• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8B
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• pp.721-729
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• 2004

In this paper, we applied a group scheduling algorithm to core nodes in an optical burst switching (OBS) network and measured its performance by simulation. For the case of core nodes with multi-channel input/output ports, performance of the group scheduling has been compared to that of the immediate scheduling. Since the group scheduling has a characteristic of scheduling a group of bursts simultaneously in a time window using information collected from corresponding burst header packets arrived earlier to a core node, simulation results show that the group scheduling outperforms the immediate scheduling in terms of both burst loss probability and channel utilization and the difference gets larger as the load increases. Another node configuration in which wavelength converters are equipped at the output ports has also been considered. In this case, even though both performance metrics of the group scheduling are almost the same as those of the immediate scheduling in the offered load range between 0.1 and 0.9, the group scheduling has lower wavelength conversion rate than the immediate scheduling by at least a factor of seven. This fact leads us to the conclusion that the group scheduling makes it possible to implement more economical OBS core nodes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.51-58
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• 2003

In this paper, we propose a group scheduling scheme to efficiently utilize network resources for core nodes in optical burst switching networks. This scheme schedules multiple bursts utilizing an interval graph to obtain the maximum stable set using the information such as arrival times and burst lengths from the collected header packets. Simultaneous scheduling of multiple bursts in a scheduling window results in lower burst loss probability and increased channel utilization than those proposed previously using one-to-one mapping. Simulation results for both cases of variable and fixed burst sizes show that the group scheduling scheme is better than the immediate scheduling, so called Latest Available Unused Channel with Void Filling, scheme in both performance metrics above mentioned.

• ETRI Journal
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• v.31 no.5
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• pp.481-488
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• 2009

This paper proposes a new multiuser scheduling algorithm that can simultaneously support a variety of different quality-of-service (QoS) user groups while satisfying fairness among users in the same QoS group in MIMO broadcast channels. Toward this goal, the proposed algorithm consists of two parts: a QoS-aware fair (QF) scheduling within a QoS group and an antenna trade-off scheme between different QoS groups. The proposed QF scheduling algorithm finds a user set from a certain QoS group which can satisfy the fairness among users in terms of throughput or delay. The antenna trade-off scheme can minimize the QoS violations of a higher priority user group by trading off the number of transmit antennas allocated to different QoS groups. Numerical results demonstrate that the proposed QF scheduling method satisfies different types of fairness among users and can adjust the degree of fairness among them. The antenna trade-off scheme combined with QF scheduling can improve the probability of QoS-guaranteed transmission when supporting different QoS groups.

• ETRI Journal
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• v.37 no.5
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• pp.888-897
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• 2015

Group scheduling is an operation whereby control packets arriving in a time slot schedule their bursts simultaneously. Normally, those bursts that are of the same wavelength are scheduled on the same channel. In cases where the support of full wavelength converters is available, such scheduling can be performed on multiple channels for those bursts that are of an arbitrary wavelength. This paper presents a new algorithm for group scheduling on multiple channels. In our approach, to reach a near-optimal schedule, a maximum-weight clique needs to be determined; thus, we propose an additional algorithm for this purpose. Analysis and simulation results indicate that an optimal schedule is almost attainable, while the complexity of computation and that of implementation are reduced.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.31
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• pp.115-123
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• 1994

Group scheduling, which is a kind of operations scheduling based on the GT concept is analyzed in a multi-stage manufacturing system. The purpose of this research is to develop and evaluate a heuristic algorithm for determining gro up sequence and job sequence within each group to minimize a complex cost function, i.e. the sum of the total pe-nalty cost for tardiness and the total holding cost for flow time, in a multi-stage manufacturing system with group setup time dependent upon group sequence. A heuristic algorithm for group sc heduling is developed, and a numerical example is illustrated. For the evaluation of the pro-posed heuristic algorithm, the heuristic solution of each of 63 problems is compared with that of random scheduling. The result shows that the proposed heuristic algorithm provides better solution in light of the proposed cost function.

• Journal of applied mathematics & informatics
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• v.24 no.1_2
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• pp.283-293
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• 2007

This paper considers single machine scheduling problems with group technology (GT) and deteriorating jobs. A sequence independent setup is required to process a job from a different group and jobs in each group are processed together. We consider the case of jobs whose processing times are a decreasing function of their starting time. The objectives of scheduling problems are to minimize the makespan and the total completion time, respectively. We also provide polynomial time algorithms to solve these problems.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1843-1850
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• 2014

In this paper, we investigate a group building based power consumption scheduling to minimize the electricity cost. We consider the demand shift to reduce the peak load and suggest the compensation function reflecting the relationship between the change of the building demand and the occupants' comfort. Using that, the electricity cost minimization problem satisfied the convexity is formulated, and the optimal power consumption scheduling algorithm is proposed based on the iterative method. Extensive simulations show that the proposed algorithm achieves the group management gain compared to the individual building operation by increasing the degree of freedom for the operation.

• Journal of Korean Institute of Industrial Engineers
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• v.9 no.1
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• pp.23-31
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• 1983

A group scheduling problem, which is production scheduling problem associated with the concept of group technology, is studied under due date constraints in multi-stage manufacturing systems. The purpose of this paper is to develop and evaluate a practical heuristic procedure for determining group sequence and job sequence within each group to minimize total tardiness in multi-stage manufacturing systems. A heuristic algorithm has been developed by introducing the concept of relative measures of job tardiness and group tardiness for job sequencing and group sequencing, respectively. A numerical example is shown to illustrate the proposed procedure. The heuristic algoirthm is tested by comparisons with problems with known optimal solutions and also with random group schedules for a set of large-size problems. Results indicate that the proposed heuristic algorithm provides good solutions with small computational requirements, and thus is viable for large size problems in practice.

• Journal of Korean Institute of Industrial Engineers
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• v.12 no.2
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• pp.33-44
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• 1986

This research is concerned with group scheduling problems in multi-stage manufacturing system with dependent setup time. The objective of the research is to develop and evaluate a heuristic algorithm for determining group sequence and job sequence within each group to minimize total tardiness in multi-stage manufacturing systems with sequence dependent group setup time. The group scheduling heuristic algorithm is developed and evaluated by comparisons with twenty-seven problems with the known optimum solutions and 144,000 random schedules of a large variety problems. The results indicate that the proposed heuristic algorithm gets the same optimum solutions for the problems and also provides the good solutions in comparison with the random schedules of the large variety problems. A numerical example is given to illustrate the heuristic algorithm.

• Journal of Korean Institute of Industrial Engineers
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• v.11 no.2
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• pp.75-85
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• 1985

The application of GT results in the mass production effect to multi-product, small lot-sized production. Group scheduling, which is operations scheduling based on the GT concept, is analyzed in a multistage manufacturing system. But the research has been limited in independent setup time models. A heuristic algorithm has been developed to minimize the mean flow time when setup times are dependent to sequence of group in multistage. For evaluation of the heuristic algorithm, the solution of heuristic algorithm is compared with that of random scheduling. The result of comparison indicates that the proposed heuristic algorithm provides good solutions with relatively fewer computational effort.