• The Transactions of the Korea Information Processing Society
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• v.2 no.1
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• pp.119-129
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• 1995

In this paper, we propose a schedulatility analysis method for real-time programs. Several approaches to anlayzing schedulability have been developed, but since these approaches use a fixed priority scheduling method and/or traverse all possible state spaces, there take place exponential time and space complexity of these methods, Therefore it is necessary to reduce the state space and detect schedulability at earlier time. Our schedulability analysis method uses a minimum unit time taken to terminate synchronization action, a minimum unit time taken to terminate actions after synchronization, and a deadline of processes to detect unschedulability at earlier time and dynamic scheduling scheme to reduce state space. We conclude that our method can detected unschedulability earlier 50 percent unit time than Fredette's method.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.2
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• pp.167-178
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• 2000

Software RAID(Redundant Arrays of Inexpensive Disks) is defined as a storage system that provides capabilities of hardware RAID, and guarantees high reliability as well as high performance. In this paper, we propose an enhanced disk scheduling algorithm and a scheme to guarantee reliability of data. We also design and implement software RAID by utilizing these mechanism to develop a storage system for multimedia applications. Because the proposed algorithm improves a defect of traditional GSS algorithm that disk I/O requests arc served in a fixed order, it minimizes buffer consumption and reduces the number of deadline miss through service group exchange. Software RAID also alleviates data copy overhead during disk services by sharing kernel memory. Even though the implemented software RAID uses the parity approach to guarantee reliability of data, it adopts different data allocation scheme. Therefore, we reduce disk accesses in logical XOR operations to compute the new parity data on all write operations. In the performance evaluation experiments, we found that if we apply the proposed schemes to implement the Software RAID, it can be used as a storage system for small-sized video-on-demand servers.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.45-46
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• 2018

본 논문에서는 시간에 엄격한(Time critical) 산업용 IoT(Industrial IoT) 환경의 무선 센서 네트워크 시스템 상의 효율적인 패킷 전달과 정확도(Accuracy) 향상을 위해 강화학습과 EDF 알고리즘을 혼합한 스케쥴링 기법을 제안한다. 이 방식은 다중 대기열(Multiple queue) 환경에서 각 대기열의 요구 정확도(Accuracy Requirement)를 기준으로 최대한 패킷 처리를 미룸으로써 효율적인 CPU자원 분배와 패킷 손실율(Packet Loss)을 조절한다. 제안하는 기법은 무선 센서 네트워크 상의 가변적이고 예측 불가능한 환경에 대한 사전지식이 없이도 요구하는 서비스의 질(Quality of service)를 만족할 수 있도록 한다. 또한 정확도를 요구조건으로 제시하여 마감시간이 중요시되는 작업에서도 효율을 최대화한다.

• Journal of the Korea Society of Computer and Information
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• v.19 no.5
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• pp.1-10
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• 2014

The proposed scheme schedules given real-time tasks so that energy consumption of multicore processors would be minimized while meeting tasks' deadline and tolerating a permanent fault based on the primary-backup task model. Whereas the previous methods minimize the overlapped time of a primary task and its backup task, the proposed scheme maximizes the overlapped time so as to decrease the core speed as much as possible. It is analytically verified that the proposed scheme minimizes the energy consumption. Also, the proposed scheme saves up to 77% energy consumption of the previous method through experimental performance evaluation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.209-221
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• 1999

Several approaches to anlayzing real-time schedulability have been presented, but since these used a fixed priority scheduling scheme and/or traverse all possible state spaces, there take place exponential time and space complexity of these methods. Therefore it is necessary to reduce the state space and detect schedulability at earlier time. This paper proposes and implements an advanced schedulability analysis algorithm to determine that is satisfied a given deadlines for real-time processes. These use a minimum execution time of process, periodic, deadline, and a synchronization time of processes to detect schedulability at earlier time and dynamic scheduling scheme to reduce state space using the transition rules of process algebra. From a result of implementation, we demonstrated the effective performance to determine schedulability analysis.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10a
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• pp.162-166
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• 2006

선행스케줄링(pre-scheduling)은 정적인 작업(periodic job)과 동적인 작업(sporadic job)을 유연하게 처리하기 위해 제안된 스케줄링 방식이다. 이 방식은 오프라인 컴포넌트와 온라인 컴포넌트로 구성되며 오프라인 컴포넌트에서는 비주기적으로 도착하는 동적인 작업들을 고려하여 정적인 작업들을 여러 부분작업으로 분할하고, 그리고 각 부분작업들의 실행시간, 준비시간, 마감시간을 부여하고 실행순서를 결정한다. 온라인 컴포넌트에서는 이 정보들을 이용하여 정적인 작업들을 정해진 실행순서에 따라 스케줄하고, 동적인 작업이 도착하면 EDF(Earliest Deadline First) 스케줄링 방식으로 처리한다. 그러나 선행스케줄링에서는 자원공유문제를 고려하지 않고 실행시간을 부여하였으므로 여러 정적인 작업들이 하나의 자원을 공유할 경우에 배타적인 자원접근을 보장하지 못한다. 본 논문에서는 단일처리기 환경에서 여러 정적인 작업들의 자원공유를 고려하여 자원의 배타적 사용을 보장하는 선행스케줄 생성기법을 제시한다. 이 기법은 각 작업의 자원 방출시간을 예측하고 예측시간에 근거하여 각 작업의 자원사용구간이 중복되지 않도록 실행시간을 결정한다.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.149-159
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• 2006

This research is a development of useful S/W program for real industry about optimal product scheduling in real plant for manufacturing polymer products. For this, we used a fine model with total amount of losses in weight(ton) as an objective for optimal scheduling and a genetic algorithm for optimization in this factory they manufacture three different products. Major products are A and B but the product which can be process in the period of products change over. They also sells them as a chap product in market. The major products have several types of packing process-bulk, pack for domestic market, pack for export. The demands of product with each packing type are increased, and frequently they failed keep the deadline for sail. Based on realistic production situation, we composed a fine modeling for optimal scheduling. And we also develop a S/W program for optimal scheduling which can be used by non-specialist in scheduling problem. We used a modified genetic algorithm and it gave us a better solution in process. We can have a result of reducing the total amount of losses in weight by half compared with the losses when existing production schedule.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.2
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• pp.45-54
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• 2008

In this paper, a dynamic GTS scheduling method based on IEEE 802.15.4 is proposed for wireless control system. The proposed method can guarantee a transmission of real-time periodic and sporadic data within the time frame in factory environment. The modified superframe of IEEE 802.15.4 was used to the dynamic scheduling method of real-time mixed traffic(periodic data, sporadic data, and non real-time message). By separating CFP and CAP properly, the sporadic and non real-time messages are transmitted effectively and guarantee real-time transmission within a deadline. The simulation results show the improvement of real-time performance of periodic and sporadic data.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.83-93
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• 2007

In this paper, we address a power-aware scheduling algorithm for a mixed real-time system which consists of periodic and sporadic tasks, each of which is characterized by its minimum period, worst-case execution requirement and deadline. We propose a dynamic voltage scaling algorithm called DVSMT(DVS for mixed tasks), which dynamically scales down the supplying voltage(and thus the frequency) using on-line distribution of the borrowed resources when jobs complete while still meeting their deadlines. With this scheme, we could reduce more energy consumption. As the proposed algorithm can be easily incorporated with RTOS(Real-Time Operating System), it is applicable for handhold devices and sensor network nodes that use a limited battery power. Simulation results show that DVSMT saves up 60% more than the existing algorithms both in the periodic-task and mixed-task systems.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.1-8
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• 2010

In this paper, we propose a scheduling strategy for grid environment that reduces resource cost. This strategy considers resource cost and job failure rate to efficiently allocate local computing resources. The key idea of our strategy is that we use two-level scheduling using remote and local scheduler. The remote scheduler determines the expected total execution times of jobs using the current network and local system status maintained in its resource database and allocates jobs with minimum total execution time to local systems. The local scheduler recalculates the waiting time and execution time of allocated job and uses it to determine whether the job can be processed within the specified deadline. If it cannot finish in time, the job is migrated other local systems, through simulation, we show that it is more effective to reduce the resource cost than the previous Greedy strategy. We also show that the proposed strategy improves the performance compared to previous Greedy strategy.