• Journal of Institute of Control, Robotics and Systems
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• v.11 no.2
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• pp.175-185
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• 2005

The scheduling methods of the distributed real-time systems have been proposed. However, they have some weak points. They did not schedule both sporadic and periodic tasks and messages at the same time or did not consider the end-to-end constraints such as precedence relations between sporadic tasks. This means that system scheduling must guarantee the constraints of practical systems and be applicable to them. This paper proposes a new scheduling method that can be applied to more practical model of distributed real-time systems. System model consists of sporadic and periodic tasks with precedence relations and sporadic and periodic messages and has end-to-end constraints. The proposed method is based on a binary search-based period assignment algorithm, an end-to-end laxity-based priority assignment algorithm, and three kinds of schedulability analysis, node, network, and end-to-end schedulability analysis. In addition, this paper describes the application model of sporadic tasks with precedence constraints in a distributed real-time system, shows that existing scheduling methods such as Rate Monotonic scheduling are not proper to be applied to the system having sporadic tasks with precedence constraints, and proposes an end-to-end laxity-based priority assignment algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.10
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• pp.75-84
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• 1997

This paper describes the development of an integrating method for process planning and scheduling activities for block assembly in shipbuilding. A block is composed of several steel plates and steel sections with the predetermined shapes according to the ship design. The parts which constitute the block are manufac- tured by cutting and/or bending operations, which are termed as machining operation in this paper. The machining operation is the first process for block assembly which influences the remaining block assembly processes. Thus process planning and scheduling for machining operation to manufacture parts for block are very important to meet the assembly schedule in the shipyard. An integrating method for process plan- ning and scheduling is developed by introducing the concept of distributed process planning and scheduling composed of initial planning, alternative planning and final planning stages. In initial planning stage, nesting parts information and machining emthods are generated for each steel plate. In alternative plan- ning stage, machine groups are selected and workcenter dispatching information is generated. In final planning stage, cutting sequences are determined. The integrated system is tested by case study. The result shows that the integrated system is more efficient than existing manual planning system.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.107-113
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• 2024

Scheduling of semiconductor test facilities has been crucial since effective scheduling contributes to the profits of semiconductor enterprises and enhances the quality of semiconductor products. This study aims to solve the scheduling problems for the wafer burn-in test facilities of the semiconductor back-end process by utilizing simulation and deep reinforcement learning-based methods. To solve the scheduling problem considered in this study. we propose novel state, action, and reward designs based on the Markov decision process. Furthermore, a neural network is trained by employing the recent RL-based method, named proximal policy optimization. Experimental results showed that the proposed method outperformed traditional heuristic-based scheduling techniques, achieving a higher due date compliance rate of jobs in terms of total job completion time.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.63-67
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• 2024

Recently, artificial intelligence (AI) workloads encompassing various industries such as smart logistics, FinTech, and entertainment are being executed on the cloud. In this paper, we address the scheduling issues of various AI workloads on a multi-tenant cloud system composed of heterogeneous GPU clusters. Traditional scheduling decreases GPU utilization in such environments, degrading system performance significantly. To resolve these issues, we present a new scheduling approach utilizing genetic algorithm-based optimization techniques, implemented within a process-based event simulation framework. Trace driven simulations with diverse AI workload traces collected from Alibaba's MLaaS cluster demonstrate that the proposed scheduling improves GPU utilization compared to conventional scheduling significantly.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.4
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• pp.201-212
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• 2002

This paper proposes a reconfigurable scheduler model that can support various real-time scheduling algorithms. The proposed model consists of two hierarchical upper and lower components, task scheduler and scheduling framework, respectively. The scheduling framework provides a job dispatcher and software timers. The task scheduler implements an appropriate scheduling algorithm, which supports a specific real-time application, based on the scheduling framework. If system developers observe internal kernel interfaces to communicate between two hierarchical components, they can implement a new scheduling algorithm independent of complex low kernel mechanism. Once a task scheduler is developed, it can be reused in a new real-time system in future. In Real-Time Linux (5), we implemented the proposed scheduling framework and several representative real-time scheduling algorithms. Throughout these implementations, we confirmed that a new scheduling algorithm could be developed independently without updates of complex low kernel modules. In order to confirm efficiency of the proposed model, we measured the performance of representative task schedulers. The results showed that the scheduling overhead of proposed model, which has two separated components, is similar to that of a classic monolithic kernel scheduler.

• Journal of Computing Science and Engineering
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• v.2 no.1
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• pp.74-97
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• 2008

A scheduling policy or a schedulability test is defined to be sustainable if any task system determined to be schedulable remains so if it behaves "better" than mandated by its system specifications. We provide a formal definition of sustainability, and subject the concept to systematic analysis in the context of the uniprocessor scheduling of periodic and sporadic task systems. We argue that it is, in general, preferable engineering practice to use sustainable tests if possible, and classify common uniprocessor schedulability tests according to whether they are sustainable or not.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.197-205
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• 1997

Manufacturers can meet the due dates of orders by using overtime, in which case, additional cost incurs for the amount of overtime. Although many studies have been reported on scheduling, only a few papers are founds on production scheduling using overtime. We consider the problem of production scheduling using overtime on a single machine, in which each job has a given due-date, a constant processing time. We assume that the daily overtime does not exceed the daily regular operation time. The objectives is to minimize the total overtimes, while meeting all due dates. We first present a mathematical model, and then suggest a heuristic algorithm for the problem.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.445-448
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• 2000

This paper considers a scheduling algorithm for high-speed routers, where the router has an N x N port input-queued switch and the input queues are composed of N VOQ(Virtual Output Queue)s at each input port. The major concern of the paper is on the scheduling mechanism for the router. The paper discusses the preferred levels of the performance measures and then develope a non-linear mixed integer programming. Additionally, the paper suggests a heuristic scheduling algorithm for efficient and effective switching.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.91-98
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• 2002

In the study, we propose, for the practical approaches of job shop scheduling, the new dispatching rules of Job shop scheduling in order to complement the practical applications in the existing researches. The performance of the new dispatching rules is compared and analyzed with the existing methods through the computer experiments in the assumed conditions. The results can be useful to improving a field application of the job shop scheduling.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2124-2126
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• 2008

In the wireless communication systems, the demand of multimedia services is also increased. Unlike typical data packets, realtime service such as VoIP packets have delay bound and low loss rate requirement. In this paper we propose a new scheduling algorithm that be able to allocate resources to the different kinds of services such as VoIP and data packet. The proposed algorithm considers both time delay and channel condition toe determine the priority. Simulation results show that the proposed algorithm works more efficiently than the conventional algorithms.