• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.1-8
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• 2002

By now, Schedulers for RMS and EDF are implemented for real-time Linux Scheduler. These Schedulers are used for do not consider there's characteristics. Missing Schedulability-test cause result that increase deadline miss rate. Also The present real-time Linux causes system halt Because of scheduling for unschedulable tasks . These appearances are very fatal for real-time system. Therefor, In this paper The peaceful schedulability-test use scheduler which is proper characteristics of RMS and EDF scheduling methods. This scheduler keeps deadline and eliminates system halt from scheduling unschedulable tasks. In this paper, we propose the schedulability-test algorithm and scheduler select algorithm for the effective management of tasks sets.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.966-968
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• 2009

In IEEE 802.16 system, it is important to allocate resources appropriately in order to the efficient utilization of resources among a variety of real-time and non real-time packets. although a lot of the real-time and non real-time packet scheduling schemes in OFDMA system have been proposed, it need to be modified to apply to IEEE 802.16 system. Since IEEE 802.16 supports five kinds of service classes, it is important to take QoS constraints of these classes into consideration. In this paper, we propose a efficient scheduling scheme to support various services by considering the QoS constraints of each classes.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.6
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• pp.36-46
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• 2002

This paper proposes an integrated scheduling mechanism for embedded system with real-time web server to meet the characteristics of real time task. The proposed scheduling mechanism may solve the so-called priority inversion problem in scheduling between urgent web requests and tasks with low priorities. The priority inversion problem happens because of operating two independent schedulers, web scheduler and operating system scheduler in a system without considering the requirements of each other. In the proposed mechanism, two schedulers are integrated in an operating system and the integrated scheduler schedules tasks for urgent web requests with real time characteristics and other application tasks together. Since all tasks are scheduled by one unified scheduler that knows the characteristics of tasks, the tasks are scheduled with their absolute priorities and thus the priority inversion problem can be eliminated. The performance is measured on a prototype embedded system with the proposed algorithm.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.7
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• pp.368-376
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• 2005

Multiprocessor architecture becomes increasingly common on real-time systems as computer hardware technology rapidly progresses and the workload of real-time systems increases. However, efficient solutions for many real-time multiprocessor scheduling problems are not known. Hence many researchers apply uniprocessor scheduling algorithms to multiprocessor scheduling or devise new algorithms based on these algorithms. Such algorithms are EDF (Earliest Deadline First), LLF (Least Laxity First), EDF-US[m/(2m-1)], and EDZL (Earliest Deadline Zero Laxity), and comparative studies on them are necessary. In this paper, we show the dominance relation of these algorithms with respect to schedulability, and we prove EDZL strictly dominates EDF. The simulation results show that EDZL has high processor utilization and it causes a small number of preemptions.

• The Transactions of the Korea Information Processing Society
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• v.3 no.6
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• pp.1418-1432
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• 1996

In addition t improved availability, replication of data can enhance performance of distributed real-time transaction processing system by allowing transactions initiated at multiple node to be processed concurrently. To satisfy both the consistency and real-time constraints, it is necessary to integrate concurrency control and atomic commitment protocols with time-driven scheduling methods. blocking caused by existing concurrency control protocols is incompatible with time-driven scheduling because they cannot schedule transactions to meet given deadlines. To maintain consistency of replicated data and to provide a high degree of schedulability and predictability , the proposed time-driven scheduling methods integrate optimistic concurrency control protocols that minimize the duration of blocking and produce the serialization by reflecting the priority transactions. The atomicity of transactions is maintained to ensure successful commitment in distributed environment. Specific time-driven scheduling techniqueare discussed, together with an analysis of the performance of this scheduling.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.467-475
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• 1999

This paper presents an algorithm for scheduling jobs in soft real-time systems. To simplify the scheduling for soft real-time systems, we introduce two-level deadline scheme. Each job in the system has two deadlines, which we call first-level and second-level deadlines, respectively. The first-level deadline is the same as the deadline in traditional real-time systems. The second-level deadline is later than the first-level deadline, and defines the latest point in time when the result is still acceptable. Partial-credit is given for jobs meeting the second-level deadline but missing the first-level deadline, whereas jobs meeting the latter are given full credit. We heuristically compute priorities of jobs in a dynamic way by combining the first-level adn second-level deadlines with the partial-credit. Simulation results indicate that our two-level scheduling algorithm is a viable approach for dealing with both soft real-time systems and temporary overloaded hard real-time systems.

• Korean Management Science Review
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• v.34 no.1
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• pp.47-56
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• 2017

We focus on the Real time Fire Scheduling Problem (RFSP), the problem of determining the sequence of targets to be fired at, for the objective of minimizing threatening probability to achieve tactical goals. In this paper, we assume that there are m available weapons to fire at n targets (> m) and the weapons are already allocated to targets. One weapon or multiple weapons can fire at one target and these fire operations should start simultaneously while the finish time of them may be different. We suggest mathematical modeling for RFSP and several heuristic algorithms. Computational experiments are performed on randomly generated test problems and results show that the suggested algorithms outperform the firing method which is generally adopted in the field artillery.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.4
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• pp.26-36
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• 2000

This paper proposes a neural network algorithm for real-time multiprocessor scheduling problem. The proposed algorithm is developed base on Hopfield neural network for a benefit of parallel processing, in order to finish a requested task within a deadline time. To compare the performance of the proposed algorithm, we used EDA and LLA algorithm that has studied real-time multiprocessor scheduling before. The proposed algorithm is implemented hardware using VHDL.

• IE interfaces
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• v.11 no.1
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• pp.119-129
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• 1998

The relative importance of Logistics in steelworks industry is rather higher among other business activities. The objective of the paper is to propose the methodology for real-time vehicle scheduling for scrap disposal in the steelworks industry. Currently, the rule necessary to assign vehicles to a specific job is strictly fixed. The paper adopts the multi-pass rule selector (MPRS) that suggests a promising rule used for vehicle dispatching for a period of time. The MPRS is regularly invoked if necessary and then evaluates a set of rule candidates to select the best rule with respect to the system performance criteria. The experiment shows that the proposed approach outperforms the current single-pass strategy.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.10
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• pp.573-580
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• 2004

A new real-time constrained dispatch scheduling (CDS) is needed for TWBP. The CDS needs to be performed at every dispatch period to decide generation power of scheduling generators and amounts of scheduling load. Therefore, the CDS is not based on real generation costs but on bidding data of market participants with some constraints such as power balance, generation limits, ancillary service, and transmission line limits. This paper selects linear programming(LP) as an optimization tool for the CDS and presents effective formulae for the LP application. This paper also presents the way of minimizing the number of variables and constraints of the LP to improve real-time applicability.