• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.183-186
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• 2002

클러스터는 부하 분산 스케줄링의 방법에 따라서 그 시스템의 성능이 달라진다. 본 논문에서는 클러스터의 한 종류인 LVS에서 제시되었던 RR, WRR, LC, WLC의 부하 분산 스케줄링을 이용하여 시스템의 각종 부하를 처리하는 방법과 클러스터의 각 서버의 성능을 측정하여 부하 분산을 결정하는 ALBM(Adaptive Load Balancing Mechanism) 방식을 비교하였다. 이 성능 평가를 하기 위하여 여러 실험 환경 설정을 하여 다양한 실험을 통하여 비교 분석 하였다. 실험을 통하여 ALMB 이 기존의 여러 스케줄링 방식에 비하여 전체적으로 좋은 성능 결과를 낳았으며 클러스터 서버간의 안정적인 부하 분산이 되는 결과를 얻었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.105-107
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• 2014

대량의 정보를 효과적으로 처리하기 위한 기술로 CPU 뿐만 아니라 iSSD 와 GPGPU 를 개별적으로 이용하는 연구가 진행되고 있다. 본 논문에서는 더 나아가 CPU, iSSD 와 GPU 를 협업시켜 프로그램 수행 성능을 향상시키는 방법을 연구한다. 이러한 이질 시스템의 협업을 위해 이질 스케줄링 알고리즘을 적용하고, 스케줄링 알고리즘에 따른 협업 시스템의 성능을 분석한다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.7
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• pp.1817-1824
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• 1999

How to efficiently and optimally schedule iterative is one of the critical issues in FMC(Flexible Manufacturing Cell). In this paper, we apply transformation rules to find the solution of the scheduling problem in FMC. These kinds of rules have already been applied for the analysis of autonomous Petri nets. Here in, transformation is intended to preserve the existence of at least one optimal solution for the scheduling problem. Some transformations rules to reduced TPN's size without changed the initial characteristics are proposed and applied to analyze the scheduling problem of FMC.

• Journal of the Korea Computer Industry Society
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• v.9 no.2
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• pp.63-68
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• 2008

The purpose of a parallel scheduling is to carry out the scheduling with the minimum synchronization overhead and bottleneck under a multiprocessor environment and to perform load balance for a parallel iteration. In this paper, analyse the conventional parallel scheduling methods and drive the problems from each method in order to achive the minimum scheduling overhead and load balance. These problems will go far toward solving the design of effective algorithm.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.11
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• pp.1333-1343
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• 1999

경성 실시간 시스템의 태스크들은 논리적으로 올바른 결과를 산출해야 하지만 또한 각자의 시간 제한 조건을 만족하여야 한다. 간격제한 스케줄링은 시간 제한 조건이 시간 간격 제한으로 주어지는 실시간 태스크들을 스케줄하기 위하여 도입되었다. 간격제한 스케줄링에서의 각 태스크들은 시간 간격 제한 조건을 갖는데, 이것은 태스크의 두 연속적인 수행의 종료시간에 대해 제한을 가한다. 다시 말해, 간격제한 스케줄링에서의 각 태스크 수행은 그 태스크의 직전 수행 완료 시간으로부터 발생하는 데드라인을 갖는다. 간격제한 태스크 스케줄링에 관한 많은 연구는 단순화 방법에 기초하고 있다. 그러나, 우리는 이 논문에서 단순화 방법을 사용하지 않고, 정적 우선순위 및 정적 분리 제한 정책을 채용한 새로운 간격제한 태스크 스케줄링 방법을 제안한다. 제안된 정적 할당 방법은 스케줄링 분석 및 구현을 매우 간단히 할 수 있으며, 또한 스케줄러의 실행시간 오버헤드를 줄일 수 있다.Abstract Tasks in hard real-time systems must not only be logically correct but also meet their timing constraints. The distance-constrained scheduling has been introduced to schedule real-time tasks whose timing constraints are characterized by temporal distance constraints. Each task in the distance-constrained scheduling has a temporal distance constraint which imposes restriction on the finishing times of two consecutive executions of the task. Thus, each execution of a task in the distance-constrained scheduling has a deadline relative to the finishing time of the previous execution of the task.Much work on the distance-constrained task scheduling has been based on the reduction technique. In this paper, we propose a new scheme for the distance-constrained task scheduling which does not use the reduction technique but adopts static priority and static separation constraint assignment policy. We show that our static assignment approach can simplify the scheduling analysis and its implementation, and can also reduce the run-time overhead of the scheduler.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.147-149
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• 2015

게놈을 위한 Bioinformatics 분석을 위해 순서가 있는 작업(Task)의 집합인 워크플로우를 특정 데드라인 이내로 수행할 것을 요청하면, 워크플로우 관리자는 데드라인을 지켜주면서 비용이 최소가 되는 방향으로 워크플로우를 수행하여야 한다. 본 논문은 클라우드 환경에서 유전알고리즘을 적용하여 이 워크플로우를 효율적으로 스케줄링하는 기법을 분석하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.191-197
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• 2008

For the efficient transmission of burst data in the time varying wireless channel, opportunistic scheduling is one of the important techniques to maximize multiuser diversity gain. In this paper, we propose a distributed opportunistic scheduling scheme for wireless LAN network. A proportional fair scheduling, which is one of the opportunistic scheduling schemes, is used for centralized networks, whereas we design distributed proportional fair scheduling (DPFS) scheme and medium access control with distributed manner. In the proposed DPFS scheme, each receiver estimates channel condition and calculates independently its own priority with probabilistic manner, which can reduce excessive probing overhead required to gather the channel conditions of all receivers. We evaluate the proposed DPFS using extensive simulation and simulation results show that DPFS obtains higher network throughput than conventional scheduling schemes and has a flexibility to control the fairness and throughput by controlling the system parameter.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.4
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• pp.64-72
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• 2003

A Web crawler is an important Internet software technology used in a variety of Internet application software which includes search engines. As Internet continues to grow, implementations of high performance web crawlers are urgently demanded. In this paper, we study how to support dynamic scheduling for a multiprocess-based web crawler. For high peformance, web crawlers are usually based on multiprocess in their implementations. In these systems, crawl scheduling which manages the allocation of web pages to each process for loading is one of the important issues. In this paper, we identify issues which are important and challenging in the crawl scheduling. To address the issue, we propose a dynamic crawl scheduling framework and subsequently a system architecture for a web crawler with dynamic crawl scheduling support. And we analysed the behaviors of Web crawler. Based on the analysis result, we suggest the direction for the design of high performance Web crawler.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1934-1939
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• 2013

In this paper, we consider the online scheduling problem of jobs with deadlines. The jobs arrive over time and the scheduling algorithm has no information about the arriving jobs in advance. The jobs have the processing time of the equal length and the goal of the scheduling algorithm is to maximize the number of jobs completed in their deadlines. The performance of the online algorithm is compared with that of the optimal algorithm which has the full information about all the jobs. The raio of the two performances is called the competitive ratio. In general, the ratio is unbouned. So the case that the online algorithm can have more resources than the optimal algorithm is considered, which is called the resource augmentation analysis. In this paper, the online algorithm have more machines. We show that the online algorithm can have the same performance as the optimal algorithm.

• Journal of Advanced Navigation Technology
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• v.2 no.1
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• pp.61-67
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• 1998

In this paper, we have described the Ramp Activity Coordination Expert System (RACES) which can solve aircraft parking problems. RACES includes a knowledge-based scheduling problem which assigns every daily arriving and departing flight to the gates and remote spots with the domain specific knowledge and heuristics acquired from human experts. RACES processes complex scheduling problem such as dynamic inter-relations among the characteristics of remote spots/gates and aircraft with various other constraints, for example, custome and ground handling factors at an airport. By user-driven modeling for end users and knowledge-driven near optimal scheduling acquired from human experts, RACES can produce parking schedules of aircraft in about 20 seconds for about 400 daily flights, whereas it normally takes about 4 to 5 hours by human experts. Scheduling results in the form of Gantt charts produced by the RACES are also accepted by the domain experts. RACES is also designed to deal with the partial adjustment of the schedule when unexpected events occur. After daily scheduling is completed, the messages for aircraft changes and delay messages are reflected and updated into the schedule according to the knowledge of the domain experts. By analyzing the knowledge model of the domain expert, the reactive scheduling steps are effectively represented as rules and the scenarios of the Graphic User Interfaces (GUI) are designed. Since the modification of the aircraft dispositions such as aircraft changes and cancellations of flights are reflected to the current schedule, the modification should be notified to RACES from the mainframe for the reactive scheduling. The adjustments of the schedule are made semi-automatically by RACES since there are many irregularities in dealing with the partial rescheduling.