• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.283-290
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• 2016

As the development of recent science and technology, high-performance computing resources is needed to solve complex problems. To reach these requirements, it has been actively studied about grid computing that consist of a huge system which bind a heterogeneous high performance computing resources into on which are geographically dispersed. However, The current research situation which are the process to obtain the best results in the limited resources and the scheduling policy to accurately predict the total execution time of the real-time task are very poor. In this paper, in order to overcome these problems, we suggested a grid computing-based risk management system which derived from the system structure and the process for improving the efficiency of the system, grid computing-based working methodology, risk policy module which can manage efficiently the problem of the work of resources(Agent), scheduling technique and allocation method which can re-allocate the resource allocation and the resources in problem, and monitoring which can manage resources(Agent).

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.71-77
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• 2013

In the information flooded situation having many thing to do, the efficient scheduling of energy and time is regarded as a very important thing for the busy modern people. Because the efficient time scheduling already became a very important key factor for a successful life, the more elaborately designed intelligent system than the previous simple event oriented scheduling system should be supported. Accordingly in this paper we propose Classified Job Scheduling System in which jobs are classified by Time value & Importance and allocated to Time frame efficiently. Especially the new method is proposed with the policy that processes the job with high time value first and concurrently allocates the job of low time vale & high importance to the preempted fixed area of time frame for continuous processing of job which has a key of success in the future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2A
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• pp.55-62
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• 2003

This paper proposes an efficient and differentiated MAC scheduling algorithm for Bluetooth systems. The proposed algorithm guarantees QoS (Quality of Service) requirement of each master-slave pair or application. Conventional MAC scheduling algorithms for Bluetooth take priority of each pair into consideration and demonstrate relatively reasonable performance. However, their performances may depend on traffic characteristic, or they are limited by overheads for signaling. In this paper, we propose a new MAC scheduling algorithm superior to the conventional algorithms from the viewpoints of throughput, delay, and supporting QoS. Our proposed algorithm is evaluated via computer simulations under various environments and compared with the conventional scheduling algorithms. Simulation results indicate that the proposed algorithm shows better performance than the existing algorithms, and can support the QoS demand of each pair.

• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.313-319
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• 2014

Additional train scheduling is often required to increase the capacity of transporting passengers or freight. In most previous studies on scheduling additional trains, operation time of the added train is designated first; and then the train operation feasibility is examined. However, it is often difficult to apply this approach to domestic trains because the density of the railroad network in Korea is high and various types of trains are in use. Moreover, for freight trains, it is even more challenging because the delay is accumulated due to lower priority whenever a freight train and a passenger train contend for a common segment of rail. In this paper, we address the additional train scheduling problem which entails finding a feasible schedule for an additional train having a fixed departure time or departure time windows. The problem is modeled as a mixed integer programming and a column generation technique is used to solve it.

• The KIPS Transactions:PartB
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• v.12B no.2 s.98
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• pp.173-180
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• 2005

In this paper, we propose an efficient real-time scheduling method of multimedia tasks for decoding frames of MPEG-2 video streams. In our task model, each frame is decoded by a separate multimedia task. The decoding task for each frame is assigned to the priority according to the precedence and importance of frames in a video stream. We use a priority-based scheduling policy in order to effectively allocate the CPU bandwidth to multimedia tasks for MPEG-2 decoding. We show how to dynamically control the fraction of the CPU bandwidth allocated to each multimedia task according to the priority. The primary purpose of our scheduling method is to enhance the real-time performance of the multimedia system by minimizing the number of decoding tasks that have missed their deadlines while reducing the decoding times of these multimedia tasks. The performance of this scheduling method is compared with that of similar mechanisms through simulation experiments.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.116-126
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• 2015

In a distributed heterogeneous computing system, the performance of a parallel application greatly depends on its task scheduling algorithm. Therefore, in order to improve the performance, it is essential to consider some factors that can have effect on the performance of the parallel application in a given environment. One of the most important factors that affects the total execution time is a critical path. In this paper, we propose the CLTS algorithm for a task scheduling. The CLTS sets the priorities of all nodes to improve overall performance by applying leveling method to improve parallelism of task execution and by reducing the delay caused by waiting for execution of critical nodes in priority phase. After that, it conditionally uses insertion based policy or duplication based policy in processor allocation phase to reduce total schedule time. To evaluate the performance of the CLTS, we compared the CLTS with the DCPD and the HCPFD in our simulation. The results of the simulations show that the CLTS is better than the HCPFD by 7.29% and the DCPD by 8.93%. with respect to the average SLR, and also better than the HCPFD by 9.21% and the DCPD by 7.66% with respect to the average speedup.

• Journal of the Korea Computer Industry Society
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• v.8 no.3
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• pp.197-206
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• 2007

The waiting delays of internet VOD users are inevitable in this policy since the services are not taken immediately upon requests but upon every scheduling points. An inefficient management of such delays makes an unfair service to users and increases the possibility of higher reneging rates. This paper proposes an efficient service scheduling scheme which improves the average waiting time of users requests and reduces the starvation problem of users requesting less popular movies. Experimental results of simulations show that the proposed scheme improves about 20 percentage of average waiting time and reduces significantly the starving requesters comparing with those of conventional methods such as FCFS and MQL.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.76-78
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• 2002

최근 멀티미디어 데이터 서버로 리눅스 시스템을 쓰는 경우가 많아 졌다. 이 경우, 멀티미디어 데이터에 관한 서비스를 효율적으로 제공할 수 있어야 한다. 이를 위하여, 본 논문에서는 기존의 리눅스 scheduling 방식이 갖는 단일레벨 run-queue 구조를 변형한 다중레벨 run-queue를 제안하였다. 기존의 단일레벨 run-queue에서는 queue 내에 프로세스의 수가 많아질수록 검색시간이 길어지는 단점이 있다. 본 논문에서는 기존의 run-queue를 여러 단계로 나누고, scheduling 과정에서 상위 queue부터 프로세스가 존재하는지를 조사하도록 스케줄러를 변형하였다. 따라서, 상위 queue에 프로세스가 있는 경우에는 하위의 queue는 더 이상 조사한 필요가 없게 되므로. 결과적으로 검색시간을 줄일 수 있게 된다. 한편, 다중 레벨의 run-queue를 사용할 경우, 이를 관리하기 위한 오버헤드가 별도로 발생한다. 본 논문에서는, 제안한 다중레벨의 run-queue 시스템의 성능을 최적화하기 위하여, queue의 적절한 개수 선정 및 각 프로세스를 어떤 queue에 넣을 것인지를 결정하는 것이 성능에 미치는 영향에 대하여 실험적으로 연구하여 새로운 스케줄러의 성능을 기존 스케줄러와 비로 분석하였다. 본 논문에서 제안한 멀티레벨 run-queue를 사용함으로써, 각 queue의 스케줄링 정책(policy)과 관련 파라메터 간을 독자적으로 변화시킬 수 있다. 따라서, 여러 가지 상황에 적합한 스케줄링을 각각의 경우에 맞게 최적화하는 것이 손쉬워 지므로 여러 분야에서 매우 유용하게 쓰일 것이다.

• Journal of KIISE:Software and Applications
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• v.32 no.8
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• pp.808-818
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• 2005

We devise a differential fixpoint computation method and develop a new worklist algorithm based on it. Compared with other differential methods, our method can deal with non-distributive systems and adopt any worklist scheduling policy satisfying restrictions imposed by differential evaluation. As a practical application, we present an interpretation framework and implement constant and alias analysis and memory lifetime analysis based on it. Our experiment shows that our method can save computation and worklist scheduling is also important in differential fixpoint evaluations.

• Journal of Advanced Navigation Technology
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• v.16 no.3
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• pp.471-479
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• 2012

In cellular femto systems, femto Base stations(f-BSs) can be installed unnecessarily and overcrowded in small areas. This will cause an interference problem and it can impact on the capacity, blocking probability, and coverage of femtocells in the shared channel systems. In this paper, we propose a load distribution scheme by using forced handover and probabilistic subchannel scheduling policy to resolve the problem. The proposed scheme operates in distributed manner though communication with neighboring f-BSs, and includes self-detection of overcrowded area and radio resource management based on measurements. We evaluate the performance of the proposed scheme in terms of average cell throughput and average throughput per users.