• Journal of the Korea Society of Computer and Information
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• v.20 no.9
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• pp.61-66
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• 2015

We investigate rate scheduling and power allocation problem for a delay constrained CDMA systems. Specifically, we determine an energy efficient scheduling policy, while each user maintains the short term (n time slots) average throughput. More importantly, it is shown that the optimal transmission strategy for the uplink is same as that of the downlink, called uplink and downlink duality. We then examine the performance of the optimum transmission strategy for the uplink and the downlink for various system environments.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.6
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• pp.3-9
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• 2015

We investigate rate scheduling and power allocation problem for a delay constrained CDMA systems. Specifically, we determine an energy efficient scheduling policy, while each user maintains the short term (n time slots) average throughput. We consider a multirate CDMA system where multirate is achieved by multiple codes. Each code can be interpreted as a virtual user. The aim is to schedule the virtual users into each time slot, such that the sum of transmit energy in n time slots is minimized. We then show that the total energy minimization problem can be solved by a shortest path algorithm. We compare the performance of the optimum scheduling with that of TDMA-type scheduling.

• Journal of the Korea Safety Management & Science
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• v.25 no.4
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• pp.131-140
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• 2023

This paper proposes an algorithm for the Unrelated Parallel Machine Scheduling Problem(UPMSP) without setup times, aiming to minimize total tardiness. As an NP-hard problem, the UPMSP is hard to get an optimal solution. Consequently, practical scenarios are solved by relying on operator's experiences or simple heuristic approaches. The proposed algorithm has adapted two methods: a policy network method, based on Transformer to compute the correlation between individual jobs and machines, and another method to train the network with a reinforcement learning algorithm based on the REINFORCE with Baseline algorithm. The proposed algorithm was evaluated on randomly generated problems and the results were compared with those obtained using CPLEX, as well as three scheduling algorithms. This paper confirms that the proposed algorithm outperforms the comparison algorithms, as evidenced by the test results.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.5 no.6
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• pp.21-32
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• 1982

The Ministry of the Energy and Resources is planning to invest a great deal of public funds in the energy conservation measures in order to conserve the energy. This study aims at applying the project scheduling model, especially to the energy conservation measures. In the study, we develop the project scheduling model, which is based on the modified Rorie-Savage problem. And the model is applied to the X-enterprise, which is one of the leading metal industry in the nation. The result shows that the model enables the top management to choose the set of projects which promises the largest profit among the entire projects. It appears that the proposed policy of the study is more profitable than the existing policy which is namely based on the qualitative consideration.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.97-99
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• 2001

분산 멀티미디어 데이터 처리는 실시간 처리, 서비스 품질의 균일성, 다수의 사용자에 대한 서비스 제공등과 같은 요구사항을 만족해야 한다. 기존의 범용 운영체제는 클라이언트/서버의 상태에 따라 주어진 서비스가 요구하는 사양을 만족하도록 관련 프로세스나 스레드들을 서로 연동시켜 운영하여야 하는 분산 멀티미디어 환경에서 적합하지 않을 수 있다. 이와같은 문제점을 해결하기 위하여 운영체제 내의 스케쥴링 정책을 바꾸는 방법이 있지만 이 방법은 커널 코드를 직접 수정해야 하기 때문에 구현상의 어려움이 많다. 이에 대한 대안으로 본 논문에서는 사용자 영역의 실시간 스케쥴러(URESPO: An User-level Real=time Scheduling Policy on distributed multimedia systems)를 제안한다. URESPO는 사용자 영역에서 실시간 스케쥴링 할 수 있는 사용자-영역의 스케쥴러를 만들어 하부 운영체제 내의 스케쥴러에게 다음에 수행할 스레드를 선정하는데 여러 가지 힌트를 줌으로써 사용자가 의도한 대로 기존 운영체제의 스케쥴링 정책을 변경할 수 있다. URESPO의 유용성은 실험을 통해 증명하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.733-750
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• 2019

Software Defined Networking (SDN) is a new network paradigm, allowing administrators to manage networks through central controllers by separating control plane from data plane. So, one or more controllers must locate outside switches. However, this separation may cause delay problems between controllers and switches. In this paper, we therefore propose a Priority-based Scheduling policy for OpenFlow (PSO) to reduce the delay of some significant traffic. Our PSO is based on packet prioritization mechanisms in both OpenFlow switches and controllers. In addition, we have prototyped and experimented on PSO using a network simulator (ns-3). From the experimental results, PSO has demonstrated low delay for targeted traffic in the out-of-brand control network. The targeted traffic can acquire forwarding rules with lower delay under network congestion in control links (with normalized load > 0.8), comparing to traditional OpenFlow. Furthermore, PSO is helpful in the in-band control network to prioritize OpenFlow messages over data packets.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.181-192
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• 2010

We develop a dispatching policy for stochastic scheduling simulation especially for a continuous manufacturing system with machine breakdowns. The proposed dispatching policy computes an urgency index with the consideration of re-heating, setup cost and remaining due date. Prioritized by the index, we execute swapping or reassigning material sequences so as to minimize the total penalty cost. To evaluate the performance of the proposed policy, a discrete event simulation is developed. With 200 data sets and 20 iterations, we compare the performance of the urgency policy with those of SPT (Shortest Processing Time) and FCFS (First Come First Serve) which are the most common policies. The result shows that the proposed policy consistently gives the lowest total costs by reducing the penalty costs for lateness.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.114-118
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• 1986

• The KIPS Transactions:PartA
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• v.8A no.3
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• pp.245-252
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• 2001

Multicomputer systems achieve high performance by utilizing a number of computing nodes. Multidimensional meshes have become popular as multicomputer architectures due to their simplicity and efficiency. In this paper we propose an efficient processor allocation scheme for 3D torus based on first-fit approach. The scheme minimizes the allocation time by effectively manipulating the 3D information an 2D information using CST (Coverage Status Table). Comprehensive computer simulation reveals that the allocation time of the proposed scheme is always smaller than the earlier scheme based on best-fit approach, while allowing comparable processor utilization. The difference gets more significant as the input load increases. To investigate the performance of the proposed scheme with different scheduling environment, non-FCFs scheduling policy along with the typical FCFS policy is also studied.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.7
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• pp.650-664
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• 2000

NOW(Network of Workstations) is considered as a platform for running parallel programs by many people. One of the fundamental problems that must be addressed to achieve good performance for parallel programs on NOW is the determination of efficient job scheduling policies. Currently most research on NOW assumes that all the workstations in the NOW have the same processing power. In this paper we consider a NOW in which workstations may have different computing power. We introduce 10 classes of space sharing-based scheduling policies that can be applied to the NOW with heterogeneous computing power. We compare the performance of these scheduling policies by using the simulator which accepts synthetically generated sequential and parallel workloads and generates the response time and waiting time of parallel jobs as performance indices of various scheduling strategies. Through the experiments the case when a parallel program is partitioned heterogeneously in proportion to the computing power of workstations is shown to have better performance than when a parallel program is partitioned into parallel processes of the same size. When the owner returns to the workstation which is executing a parallel process, the policy which just lowers the priority of the parallel process shows better performance than the one which migrates the parallel process to a new idle workstation. Among the policies which use heterogeneous partitioning and process priority lowering, the adaptive policy performed best across the wide range of inter-arrival time of parallel programs but when the load imbalance among parallel processes becomes very high, the modified adaptive policy performed better.