• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1348-1351
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• 1996

In field bus network, field device are connected with a medium. Because a medium must be shared for transmitting data, there are random delay time when data arrive destination station. It is difficult that all data packets are guaranteed synchronization and real-time restriction. In this paper, we show an algorithm that makes network utilization to maximum, guarantees real-time restriction, calculates sampling time at all control loop.

• 한국통신학회논문지
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• 제19권7호
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• pp.1304-1320
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• 1994

실시간 시스템에는 정확한 계산 기법과 부정확한 계산 기법이 있다. 부정확한 계산 기법은 실시간 시스템에서 스케쥴링의 유연성을 제공하는 수단이다. 지금까지 큐잉이론을 이용한 부정확한 스케쥴링에 관한 연구들은 태스크들의 평균 결과의 질과 평균 대기시간을 정충한 때의 비용과 장점들을 명확하게 수량화하는 것들이었다. 이논문은 두개의 부정확한 스케쥴링 방법을 사용할 때, 어떤 태스크가 부정확한 계산이 될 부정확한 확률들을 구하였으며 또한, 이런 두 방법의 부정확한 확률들의 여러 단조형 부정확한 시스템 매개변수들에 대한 의존성을 비교 분석하였다.

• Industrial Engineering and Management Systems
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• 제15권3호
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• pp.278-288
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• 2016

Automation ensures accurate and well-organized container transportation in container terminals. This paper addresses operational issues such as equipment scheduling and the coordination between various pieces of equipment in a rail-based automated container terminal. Containers are relayed using multiple types of equipment from road trucks to a vessel and vice versa. Therefore, handshaking is required during a container transfer between different pieces of equipment. Synchronization between the schedules of all the equipment is important to reduce equipment waiting times and the time required for transporting containers, which results in a short turnaround time for a vessel. This paper proposes an integrated control system with the objective of synchronizing the operations of different types of equipment, provides a list of decisions to be made by the control module of each type of equipment, and shows all the required information transfers between control modules. A scheme for the integrated scheduling of multiple types of equipment is proposed. The decisions made by each control module in a real-time fashion are listed with detailed explanations, and the information transfer between managers in a real-time situation at the proposed terminal is described.

• 제어로봇시스템학회논문지
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• 제8권5호
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• pp.363-372
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• 2002

In ship operation, the roll motions can seriously degrade the performance of mechanical and personnel effectiveness. So many studies for the roll stabilization system design have been performed and good results have been achieved. In many studies, the stabilizing fins are used. Recently rudders, which have been extensively modified, have been used exclusively to stabilize the roll. But, in the roll stabilization control system, the control performance is very sensitive to the ship speed. So, we can see that it is important to consider the ship speed in the rudder roll control system design. The gain-scheduling control technique is very useful in the control problem incorporating time varying parameters which can be measured in real time. Based on this fact, in this paper we examine the;$H_{\infty}$-Gain Scheduling control design technique. Therefore, we assume that a parameter, the ship speed which can be estimated in real time, is varying and apply the gain-scheduling control technique to design the course keeping and anti-rolling control system far a ship. In this control system, the controller dynamics is adjusted in real-time according to time-varying plant parameters. The simulation result shows that the proposed control strategy is shown to be useful for cases when the ship speed is varying and robust to disturbances like wind and wave.

• 산업공학
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• 제11권1호
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• pp.119-129
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• 1998

The relative importance of Logistics in steelworks industry is rather higher among other business activities. The objective of the paper is to propose the methodology for real-time vehicle scheduling for scrap disposal in the steelworks industry. Currently, the rule necessary to assign vehicles to a specific job is strictly fixed. The paper adopts the multi-pass rule selector (MPRS) that suggests a promising rule used for vehicle dispatching for a period of time. The MPRS is regularly invoked if necessary and then evaluates a set of rule candidates to select the best rule with respect to the system performance criteria. The experiment shows that the proposed approach outperforms the current single-pass strategy.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.716-719
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• 1999

In this paper, a real-time control system for robot manipulator is implemented using real-time operating system with capabilities of multitasking, intertask communication and synchronization, event-driven, priority-driven scheduling, real-time clock control, etc. The hardware system with VME bus and related devices is developed and applied to implement a dynamic learning control scheme for robot manipulator. Real-time performance of the proposed dynamic learning controller is tested for tasks of tracking moving objects and compared with the conventional servo controller.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제15권2호
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• pp.89-97
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• 2009

유비쿼터스 환경에서 널리 사용되고 있는 내장형 시스템에서는 메모리 사용량의 감소와 신뢰성 등의 이유로 쓰레드 기반 프로그래밍 모델보다는 이벤트-구동형 프로그래밍 모델을 채용하는 경우가 많다. 그러나 내장형 시스템의 소프트웨어가 점점 더 복잡해지면서, 내장형 시스템을 위한 소프트웨어를 이벤트-구동형 프로그래밍 모델의 단일 이벤트 핸들러로 프로그램 하는 것은 매우 어려운 과제가 되고 있다. 본 논문에서는 내장형 시스템의 설계에 비선점형 스케줄링 기법을 도입하기 위하여, 다항시간의 스케줄 가능성 평가를 위한 충분조건과 이를 이용한 효율적인 스케줄 가능성 검사 방법을 제시하며, 또한 내장형 시스템에서의 서브-태스크의 활용이 비선점형 스케줄링을 채용했을 때의 단점인 낮은 처리기 이용률을 극복할 수 있는 방안임을 보인다.

• 대한산업공학회지
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• 제25권3호
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• pp.369-381
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• 1999

Recently, the researches of real-time scheduling that manage flexibly system movement are being progressed by using simulation. But because the existing researches are focused on state change of whole system and selected dispatching with real-time, it could not reflect the state changes of each work center accurately, Therefore, the main core of this paper is to examine the state of workcenter, to select the optimal dispatching dynamically through simulation, and to present the algorithm that can manage actively on state of workcenter. Also, performance measure was used the mean tardiness and mean flow time that are used existing researches.

• 한국경영과학회지
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• 제30권2호
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• pp.29-40
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• 2005

In this research, we propose packet scheduling algorithm considering different QoS characteristics of real-time traffic and non-real-time traffic in the next generation wireless communication system serving the multimedia traffic and a new efficient framing method cooperated with this packet scheduler. When the selected traffic classes of the selected users are transmitted, our proposed framing method can increase the number of serviced traffic classes by mixing the many different traffic classes within one frame considering data rate decided by the allocated AMC (Adaptive Modulation and Coding) option. Using this proposed method, the fairness among the traffic classes can be achieved and the system performance for total throughput and delay can be enhanced. Simulations are performed to analyze the performance of the proposed framing method. Our proposed packet scheduler and framing method will be applied to the next generation multimedia wireless communication system serving many traffic classes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권9호
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• pp.1492-1512
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• 2011

Due to multiple hops, mobility and time-varying channel, supporting delay sensitive real-time traffic in wireless local area network-based (WLAN) mesh networks is a challenging task. In particular for real-time traffic subject to medium access control (MAC) layer control overhead, such as preamble, carrier sense waiting time and the random backoff period, the performance of real-time flows will be degraded greatly. In order to support real-time traffic, an efficient adaptive packet scheduling (APS) scheme is proposed, which aims to improve the system performance by guaranteeing inter-class, intra-class service differentiation and adaptively adjusting the packet length. APS classifies incoming packets by the IEEE 802.11e access class and then queued into a suitable buffer queue. APS employs strict priority service discipline for resource allocation among different service classes to achieve inter-class fairness. By estimating the received signal to interference plus noise ratio (SINR) per bit and current link condition, APS is able to calculate the optimized packet length with bi-dimensional markov MAC model to improve system performance. To achieve the fairness of intra-class, APS also takes maximum tolerable packet delay, transmission requests, and average allocation transmission into consideration to allocate transmission opportunity to the corresponding traffic. Detailed simulation results and comparison with IEEE 802.11e enhanced distributed channel access (EDCA) scheme show that the proposed APS scheme is able to effectively provide inter-class and intra-class differentiate services and improve QoS for real-time traffic in terms of throughput, end-to-end delay, packet loss rate and fairness.