• Journal of Intelligence and Information Systems
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• v.1 no.1
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• pp.61-72
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• 1995

Dynamic and explicit ordering of strategies is a key process in modeling knowledge-level problem-solving behavior. This paper addressed the important problem of howl to make the scheduler more knowledge-intensive in a way that facilitates the acquisition, integration, and maintenance of the scheduler control knowledge. The solution a, pp.oach described in this paper involved formulating the scheduler task as a heuristic classification problem, and then implementing it as a classification expert system. By doing this, the wide spectrum of known methods of acquiring, refining, and maintaining the knowledge of a classification expert system are a, pp.icable to the scheduler control knowledge. One important innovation of this research is that of recursive heuristic classification : this paper demonstrates that it is possible to formulate and solve a key subcomponent of heuristic classification as heuristic classification problem. Another key innovation is the creation of a method of dynamic heuristic classification : the classification alternatives that are selected among are dynamically generated in real-time and then evidence is gathered for and aginst these alternatives. In contrast, the normal model of heuristic classification is that of structured selection between a set of preenumerated fixed alternatives.

• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.394-400
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• 2022

The radio resources available in a wireless network system are limited. Therefor, job of managing resources is not easy task. Because the resources are shared among the UEs that are connected, the process of assigning resources must be carefully controlled. The packet scheduler in an LTE network is in charge of allocating resources to the user equipment (UE). Femtocells networks are being considered as a promising solution for poor channel performance for mulitple environments. The implementation of femtocells into a macrocell (traditional base station) would boost the capacities of the cellular network. To increase femtocells network capacity, a reliable Packet Scheduler mechanism should be implemented. The Packet Scheduler technique is introduced in this paper to maximize capacity of the network while maintaining fairness among UEs. The proposed solution operates in a manner consistent with this principle. An analysis of the proposed scheme's performance is conducted using a computer simulation. The results reveal that it outperforms the well-known PF scheduler in terms of cell throughput and average throughput of UEs.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.50-60
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• 2004

Recently, most of the embedded system is required not only many functions but also real-time characteristics in purpose. In the hard real-time system, especially, strict deadline of periodic task can affect the performance of the system. In this paper, we design and implement the scheduler based on RM(Rate-Monotonic) rule. This scheduler makes feasible patterns based on EDF(Earliest deadline first) rule with extended schedulability inspection before execution, for periodic task-set that has high CPU utilization and then, execute periodic task-set depended on feasible patterns. The feasible pattern formed into EDF rule is capable of the efficiency of CPU up to 100 percentage and by the referenced execution of the feasible pattern is possible of removing the red-time scheduling overhead that is the defect of the order of dynamic assignment rule.

• Journal of the Korea Society of Computer and Information
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• v.15 no.7
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• pp.1-10
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• 2010

The power of computational Grid resources can be utilized on users desktop by employing workflow managers. It also helps scientists to conveniently put together and run their own scientific workflows. Generally, stage-in, process and stage-out are serially executed and workflow systems help automate this process. However, as the data size is exponentially increasing and more and more scientific workflows require multiple processing steps to obtain the desired output, we argue that the data movement will possess high portion of overall running time. In this paper, we improved staging time and design a new scheduler where the system can execute concurrently as many jobs as possible. Our simulation study shows that 10% to 40% improvement in running time can be achieved through our approach.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.9-15
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• 2014

In this paper, We propose a block reallocation algorithm for reducing network traffic in Hadoop cluster. The scheduler of Hadoop cluster receives a job from users. And the job is divided into multiple tasks assigned to nodes. At this time, the scheduler allocates the task to the node that satisfied data locality. If a task is assigned to the node that does not have the data(block) to be processed, the task is processed after the data transmission from another node. There is difference of workload among nodes because blocks in cluster have different access frequency. Therefore, the proposed algorithm relocates blocks according to the task allocation pattern of Hadoop scheduler. Eventually, workload of nodes are leveled, and the case of the task processing in a node that does not have the block to be processing is reduced. Thus, the network traffic of the cluster is also reduced. We evaluate the proposed block reallocation algorithm by a simulation. The simulation result shows maximum 23.3% reduction of network consumption than default delay scheduling for jobs processing.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.1
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• pp.38-46
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• 2011

The OPRoS (Open Platform for Robotic Service) framework provides uniform operating environment for service robots. As an OPRoS-based service robot has to support real-time as well as non-real-time applications, application of Windows NT kernel based operating system can be restrictive. On the other hand, various benefits such as rich library and device support and abundant developer pool can be enjoyed when service robots are built on Windows NT. The paper presents a user-mode component scheduler of OPRoS, which can provide near real-time scheduling service on Windows NT based on the restricted real-time features of Windows NT kernel. The component scheduler thread with the highest real-time priority in Windows NT system acquires CPU control. And then the component scheduler suspends and resumes each periodic component executors based on its priority and precedence dependency so that the component executors are scheduled in the preemptive manner. We show experiment analysis on the performance limitations of the proposed scheduling technique. The analysis and experimental results show that the proposed scheduler guarantees highly reliable timing down to the resolution of 10ms.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.375-384
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• 2005

General purpose operating systems are Increasingly being used for serving time-sensitive applications. These applications require soft real-time characteristics from the kernel and from other system-level services. In this paper, we explore various operating systems techniques needed to support time-sensitive applications and describe the design of MUSMA(Multi-level Scheduler for Multimedia Application). MUSMA is a framework that combination of user-level top scheduler and kernel-level bottom scheduler. We develope MUSMA in linux environment and it's performance is evaluated. Experiment result shows that it is possible to satisfy the constraints of multimedia in a general purpose operating system without significantly compromising the performance of non-realtime applications.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.7
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• pp.788-812
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• 1999

본 논문에서는 범용 워크스테이션 환경하에서 수행되는 멀티미디어 응용프로그램(application)을 지원하기 위한 비례지분 방식의 CPU 스케줄러를 제시한다. 이러한 목적을 위하여 일반적 태스크의 지원을 위해 설계된 스트라이드 스케줄러를 확장한다. 멀티미디어 응용프로그램의 시간 요구사항을 명시하기 위하여 새로운 스케줄링 파라미터들을 도입한다. 비율조정기를 도입한 결과 스케줄링의 정확도의 오차는 O(1)로 감소하였다. 별도의 태스크 그룹을 설정하여 상대적 지분과 절대적 지분을 부여했다. 모의실험을 사용하여 스케줄러의 성능을 평가하였다. 그 결과, 제안된 스케줄러는 증가된 정확도와 적응성 및 유연성을 가짐을 알 수 있었다. Abstract This paper presents a proportional-share CPU scheduler which can support multimedia applications in a general-purpose workstation environment. For this purpose, we have extended the stride scheduler which is designed originally for conventional tasks. New scheduling parameters are introduced to specify timing requirements of multimedia applications. Through the use of the rate regulator, the accuracy error of the scheduling is reduced to O(1). Separate task groups are proposed to represent both relative shares and absolute shares. The proposed scheduler is evaluated using a simulation study. The results show that the proposed scheduler achieves improved accuracy and adaptability as well as flexibility.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.219-221
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• 1995

This paper proposes a model for simulation and performance evaluation of distributed computer systems(DCS). The model is composed of operating system(OS), resource, task, environment submodel. Task Flow Graph(TFG) is suggested to describe the relation between tasks. This paper considers task response time, the scheduler's ready queue length, utilization of each resource as performance indices. The distributed system of Continuous Annealing Line(CAL) in iron process is simulated with the proposed model.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.946-951
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• 2009

The small multi-jointed robots for most education are developed with the way of firmware. But the firmware may be very difficult to develop as gradually increasing throughputs and control routines. Due to limit of firmware we try to use on RTOS, but hard to adapt on the small multi-jointed robots. It would be hard to install RTOS into the small multi-jointed robots because of the size capacity of RTOS, and lack of libraries for control of the particular hardware. Moreover, even its RTOS with many functions causes its to make overheads scheduling, TCB (Task Control Block), and task states. Also to keep maintenance of RTOS, it is composed of components for the whole structure of my proposed RTOS. Additionally, We provided with libraries of servo motor and sensor control and developed RMS (Rate Montonic scheduler) to handle tasks on real time and reduce overheads. Therefore, It is possible to work the fixed priority and task preemptive way. We show one example of the multi-jointed robot installed with my proposed RTOS, which shows to obstacle avoidance and climbing up the slope.