• Journal of Electrical Engineering and information Science
• /
• 제3권3호
• /
• pp.396-401
• /
• 1998

An optimal algorithm is presented for feasibility test and scheduling of real-time tasks where tasks are preemptable and created dynamically. Each task has an arbitrary creation time, ready time, maximum execution time, and deadline. Feasibility test and scheduling are conducted via the same algorithm. Time complexity of the algorithm is O(n) for each newly created task where n is the number of tasks. This result improves the previous result of O(n log n). It is shown that the algorithm can be used for scheduling tasks with different levels of importance. Time complexity of the algorithm for the problem is O(n\ulcorner) which improves the previous results of O(n\ulcorner log n).

• 대한전기학회논문지:시스템및제어부문D
• /
• 제51권7호
• /
• pp.294-301
• /
• 2002

A new dynamic scheduling algorithm is proposed for CAN-based real-time system in this paper. The proposed algorithm is extended from an existing EDS(Earliest Deadline Scheduling) approach having a solution to the priority inversion. Using the proposed algorithm, the available bandwidth of network media can be checked dynamically, and consequently arbitration delay causing the miss of deadline can be avoided. Also, non-real time messages can be processed with their bandwidth allocation. Full network utilization and real-time transmission feasibility can be achieved through the algorithm. To evaluate the performance of algorithm, two simulation tests are performed. The first one is transmission data measurement per minute for periodic messages and the second one is feasibility in the system with both periodic messages and non-real time message.

• 한국항해학회지
• /
• 제24권5호
• /
• pp.361-371
• /
• 2000

This paper treats a genetic algorithm for ship scheduling problem in set packing formulation. We newly devised a partition based representation of solution and compose initial population using a domain knowledge of problem which results in saving calculation cost. We established replacement strategy which makes each individual not to degenerate during evolutionary process and applied adaptive mutate operator to improve feasibility of individual. If offspring is feasible then an improve operator is applied to increase objective value without loss of feasibility. A computational experiment was carried out with real data and showed a useful result for a large size real world problem.

• 산업공학
• /
• 제19권2호
• /
• pp.153-159
• /
• 2006

The research of scheduling algorithms for operating the facility of exhibition and convention can be hardly found in published papers. This study is to find problems in the process of operating the facility of exhibition and convention and to develop the scheduling algorithm satisfying those problems. The scheduling algorithm of this paper is developed through constructing the mathematical model and analyzing the mathematical structure of variables and constraints in that model. The scheduling algorithm developed in this paper consists of the first stage of scheduling, the second stage of feasibility routine and the third stage of improving scheduling results. Some experimental results are given to verify the effectiveness of the scheduling algorithm developed in this paper.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.1048-1051
• /
• 1996

In this paper, we present real-time S/W architecture and techniques such as real-time scheduling, synchronization, and etc. for implementation of a real-time control system for driving multi-motors. Simulation shows feasibility of real-time S/W techniques presented here.

• 대한전기학회논문지:전력기술부문A
• /
• 제54권12호
• /
• pp.597-602
• /
• 2005

The introduction of competition in electricity market emphasizes the importance of sufficient transmission capacities to guarantee various electricity transactions. Therefore, when dispatch scheduling, transmission security constraints should be considered for the economic and stable electric power system operation. In this paper, we propose an optimal dispatch scheduling algorithm incorporating transmission security constraints. For solving these constraints, the dispatch scheduling problem is decomposed into a master problem to calculate a general optimal power flow (OPF) without transmission security constraints and several subproblems to inspect the feasibility of OPF solution under various transmission line contingencies. If a dispatch schedule given by the master problem violates transmission security constraints, then an additional constraint is imposed to the master problem. Through these iteration processes between the master problem and subproblems, an optimal dispatch schedule reflecting the post-contingency rescheduling is derived. Moreover, since interruptible loads can positively participate as generators in the competitive electricity market, we consider these interruptible loads active control variables. Numerical example demonstrates efficiency of the proposed algorithm.

• 대한산업공학회지
• /
• 제25권3호
• /
• pp.298-309
• /
• 1999

In this study, we attempt to solve the loading and scheduling problems of an FMS in an integrated manner. We propose an integrated approach and its solution methodologies which can fully exploit the flexibility of an FMS effectively and make decisions about tool allocation, machine selection, and job sequencing simultaneously. The proposed approach consists of two main modules : 'schedule generating module' which makes partial schedules and 'tool-allocation checking module' which investigates the feasibility of tool-allocation for unscheduled tasks. Utilizing two interacting modules, we can finally settle the loading and scheduling problems. Experimental results show that in most cases the proposed integrated approach outperforms existing hierarchical approaches in the scheduling performance and the computational time required. In addition to that, the difference between the two approaches tends to increase when the number of part types and the number of alternative machines increase and the tool constraints become tight. To conclude, the experimental results show that the proposed approach is a viable one for solving practical problems.

• 경영과정보연구
• /
• 제14권
• /
• pp.67-77
• /
• 2004

Although project management for new product development is a very important issue, only a few approach from project scheduling has been made. The traditional project scheduling research has focused on the project network with certainty, but the new product development project has some uncertainties in network; Some activities may not need to be peformed, and/or some precedent relationships between activities may not need to be kept. In this paper, a simulation model is introduced in order to reflect uncertainties in project network for new product development. This simulation model can be used as a project scheduling technique for product development. By repeating the simulation, the degree of the risk and the feasibility of the project can be assessed.

• 제어로봇시스템학회논문지
• /
• 제16권4호
• /
• pp.403-410
• /
• 2010

The switched Ethernet has many features for real-time communications such as providing traffic isolation, large bandwidth, and full-duplex links, and so on. The switched Ethernet, however, cannot guarantee the timely delivery of a real-time message because message delay increases when collisions occurs at the output ports and message loss can even occur due to the overflow at the output buffer. Recently, many research efforts have been done to use the switched Ethernet as an industrial control network. In the industrial control network, sensors periodically sense the physical environment and transmit the sensed data to an actuator, and the periodic messages from sensors to actuators have typically real-time requirements such that those messages must be transmitted within their deadlines. This paper first suggests a feasible condition for EDF (Earliest Deadline First)-based scheduling of periodic messages on a synchronized switched Ethernet and a message scheduling algorithm which satisfies the proposed feasible condition. Pedreiras, et al. [10] suggested a feasible condition for message scheduling on the Ethernet (shared media Ethernet), but there has been no research result on the scheduling condition on the switched Ethernet until now. We compared the real-time message scheduling capacity between the Ethernet and the switched Ethernet by simulation. The simulation result shows that the message scheduling capacity of the Ethernet has almost remained constant as the number of nodes on the network increases, but, in the case of the switched Ethernet, the message scheduling capacity has increased linearly according to the number of nodes on the network.

• 경영과학
• /
• 제18권2호
• /
• pp.1-10
• /
• 2001

Due to environmental change in market, delivery satisfaction to customer end redaction of LeadTime are critical In the Make-to-Order manufacturing system. This paper focuses on Order Feasibility Decision System Based on SNS System. We suggest BOP (Bill of Process) in which aggregated information is used When the load p1anning problem is solved while more detailed information is used when the scheduling problem is solved.