• 전기저널
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• 9호통권81호
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• pp.12-20
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• 1983

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.83-91
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• 2015

This paper presents preventive and emergency control measures for on line transient stability (security) enhancement. For insecure operating state, generation rescheduling based on a real power generation shift factor (RPGSF) is proposed as a preventive control measure to bring the system back to secure operating state. For emergency operating state, two emergency control strategies namely generator shedding and load shedding have been developed. The proposed emergency control strategies are based on voltage magnitudes and rotor trajectories data available through Phasor Measurement Units (PMUs) installed in the systems. The effectiveness of the proposed approach has been investigated on IEEE-39 bus test system under different contingency and fault conditions and application results are presented.

• 전자공학회논문지A
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• 제28A권12호
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• pp.73-87
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• 1991

This paper presents a new approach to the scheduling problem in the high level synthesis. In this approach, iterative rescheduling processes starting with ASAP(As Soon As Possible) scheduling result are performed in a branch-and-bound manner so to arrive at the scheduling result of the lowest hardware cost under the given timing constraint. At each iteration step, only the selected nodes are considered for rescheduling, and the lower bound cost estimation is performed to avoid the unnecessary attempts to search for an optimal result. This branch-and-bound method turns out to be effective in pruning the search space, and thus reducing run time considerably in many cases.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1995년도 춘계공동학술대회논문집; 전남대학교; 28-29 Apr. 1995
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• pp.760-771
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• 1995

생산시스템에서의 스케쥴링에 관한 연구는 단일기계작업 스케쥴링으로부터 유연생산시스템(FMS)에 이르기까지 매우 광범위하게 이루어져 왔으며, 정수계획법, 동적계획법, Branch and Bound, PERT/CPM, 그리고 기타의 휴리스틱 기법등 많은 연구결과를 찾아볼수 있다. 그러나, 대부분의 연구는 소규모의 문제를 대상으로 이루어진 것으로 대규모의 현실세계 문제를 풀기에는 부적절한 것으로 판명되었다. 또한, 적용이 가능한 휴리스틱(Heuristic) 기법들도 현실세계와는 맞지 않는 많은 가정하에서 주어진 목적함수를 극대화하도록 개발되었기 때문에 현실적인 문제를 풀기 위해서는 각종 가정을 완화시킴으로써 휴리스틱을 현실에 적용하기 위한 또 다른 연구가 필요하게 되었다. 따라서, 이 연구에서는 새로운 휴리스틱을 개발하기보다는 기존의 휴리스틱 기법을 그대로 이용하면서 현실세계의 문제에서 발생하는 동적(dynamic) 스케쥴링과 재스케쥴링(rescheduling) 문제를 해결하는 시스템을 설계, 구현하는데 초점을 맞추고 있다. 특히, 데이터베이스 접근법을 사용함으로써, 가용자원의 수가 증감하거나 새로운 작업이 추가되는 등 기존의 가정을 상당부분 완화시킨 동적스케듈링 환경하에서도 재스케쥴링이 가능한 동적 재스케쥴링(dynamic rescheduling)시스템을 설계, 구현하였으며, 이의 세부기능을 보완하는 작업이 계속되고 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1028-1031
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• 1996

Dynamic scheduling is very important in constructing CIM and improving productivity of chemical processing systems. Computation at the scheduling level requires mostly a long time to generate an optimal schedule, so it is difficult to immediately respond to actual process events in real-time. To solve these problems, we developed dynamic scheduling algorithms such as DSMM(Dynamic Shift Modification Method), PUOM(Parallel Unit Operation Method) and UVVM(Unit Validity Verification Method). Their main functions are to minimize the effects of unexpected disturbances such as process time variations and unit failure, to predict a makespan of the updated dynamic schedule and to modify schedule desirably in real-time responding to process time variations. As a result, the algorithms generate a new pertinent schedule in real-time which is close to the original schedule but provides an efficient way of responding to the variation of process environment. Examples in a shampoo production batch process illustrate the efficiency of the algorithms.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2004년도 춘계학술대회 논문집
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• pp.77-82
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• 2004

자동차 공장에서의 생산스케줄은 차체공장에서부터 시작되는데 가장 이상적인 생산스케줄은 차체공장의 생산스케줄이 최종 조립라인의 조립스케줄과 동일하게 구성이 되는 것인데 차체공장, 도장공장, 조립공장의 생산 방식이 서로 다르므로 각각의 생산스케줄 목표에 맞게 투입순서를 조절해야 한다. 이를 위해서 WBS(White Body Storage), CRS(Color Rescheduling Storage), PBS(Painted Body Storage)라는 세 개의 주요 완충공간을 이용한다. 본 논문에서는 시뮬레이션 사례연구를 통하여 CRS와 PBS의 효율적인 운영을 위해 전용레인 설치를 검토하였다. 그 결과 전용레인을 설치하였을 경우 CRS에서는 그룹화비율이 감소하고, 동시에 회송차량이 증가하므로 효과적인 방법이 아님을 알 수 있었다. PBS에 전용레인을 설치한 경우에도 접근금지조건을 위반하는 차량과 회송차량이 증가하여 효율적이지 못함을 알 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.97-100
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• 2001

This paper describes preventive control for transient stability. Preventive control encompasses in general a twofold problem : Severity assessment of a instability originating from the occurrence of a dangerous contingency, and Choice of an action able to stabilize it. In this paper we assess contingencies in a power systems using PASF(Power Angle Shape Filtering) and control power systems by a generation rescheduling. The proposed method is applied to prevent loss of synchronism of all the generators at a site, KEPCO Systems.

• International Journal of Railway
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• 제6권1호
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• pp.7-12
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• 2013

This paper provides an overview of Pakistan Railways scheduling and rescheduling. First of all, Pakistan Railways is introduced with its brief history and importance in this country. Assets of this network with passengers and freight using this are given. Current hope less situation is leading to privatization of this system as well as promoting short distance traveler to use road and Government efforts to retain is also presented. Train scheduling in Pakistan is being done manually, based on manual time distance graph preparation and resolution of conflicts based on manager's experience and ability. In Real-time management of this traffic Lahore head office is connected with six control stations in the Pakistan, decision for resolution of any disturbance is coordinated among them. It is recommended that computer aided tools must be developed for this system to help traffic managers and it is needed to invest on the segments to increase their speed limits which might attract passengers to use this mode of transportation with high priority.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권4호
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• pp.398-408
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• 2016

Based on non-completely hybrid flow line scheduling of panel block in shipbuilding, several uncertain factors influencing the problem were analyzed in a real environment, and a nonlinear integer programming model was built for each sub-scheduling problem. To narrow the difference between theory and application, rolling horizon and rescheduling methods are proposed. Moreover, with respect to the uncertainty of processing time, arriving time and due time, we take the minimizing of the early and delayed delivery costs as the objective, and establish an evaluation with a global penalty function. Finally, numerical experiments and a simulation analysis were undertaken to demonstrate the effectiveness of the model and algorithm.

• Industrial Engineering and Management Systems
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• 제7권1호
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• pp.23-33
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• 2008

This paper proposes an approach to monitoring and scheduling methods for repetitive MIMO-FIFO DESs. We use max-plus algebra for modeling and formulation, known as an effective approach for controller design for this type of system. Because a certain type of linear equations in max-plus algebra can represent the system's behavior, the principal concerns in past researches were how to solve the equations. However, the researches focused mainly on analyses of the relation between inputs and outputs of the system, which implies that the changes or the slacks of internal states were not clarified well. We first examine several properties of the corresponding state variables, which contribute to finding and tracing the float times in each process. Moreover, we provide a rescheduling method that can take into account delays or changes of the internal states. These methods would be useful in schedule control or progress management.