• 산업기술연구
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• 제27권A호
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• pp.61-67
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• 2007

The construction machine is the composite machine assembled by about 30,000 parts. Excavator, one kind of a construction machine, plays the leading role for export of construction equipment. It is generally impossible to produce all of the items within one company. Especially the supply of hydraulic control valves, one of the core part of the construction equipment, depends on the import heavily. So it is important to make an efficient production plan of hydraulic control valves in the company. The most important thing for the production scheduling of a hydraulic control valve is to make production schedule keeping the start date for assembly line for an excavator and to make minimization of the stock level. The production plan of hydraulic control valve includes the decision of the quantity supplied by subcontractor. This paper presents a scheme for a scheduling system of the hydraulic control valve considering the schedule of the assembly line for excavator production. This paper provides a methodology, which can make a plan of supply and production and generate a detailed schedule for daily production.

• 제어로봇시스템학회논문지
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• 제5권6호
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• pp.714-723
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• 1999

This paper presents a short-term scheduling algorithm for the operation of steelmaking processes. The scope of the problem covers refining of the hot iron transferred form a blast furnace, ladle treatment, continuous casting, hot-rolling, and coiling for the final products that should satisfy the given demand. The processing time at each unit depends on how much the batch amount is treated, and te dedicated intermediate storage with finite capacity between the units is considered. Resource constraints and initial amount of each state are incorporated into the presented scheduling model for the algorithm of on-line scheduling. We propose amixed integer linear programming (MILP) model with two objectives for the scheduling. The first is to maximize the total profit while atisfying the due date constraint for each product. And the second is to minimize the total processing time, makespan, while satisfying the demand for each product. Especially, we observe the effect of penalizing the intermediate storage and the inventory level of the final product on the scheduling results.

• 한국멀티미디어학회논문지
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• 제7권10호
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• pp.1443-1451
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• 2004

본 논문에서는 무선 네트워크에서 모바일 호스트가 수신 호스트인 경우, 기지국에서 패킷을 전송할 때에 목적지 모바일 호스트까지의 링크 상태를 미리 예측한 후에 예측된 정보를 이용하여 전송 효율을 높일 수 있는 새로운 패킷전송 메커니즘을 제안한다. 제안된 패킷전송 메커니즘에서는 패킷을 전송하기 전에 미리 예측된 정보를 이용하여 패킷 스케줄링이 이루어지기 때문에 전체 패킷 전송 시간을 줄일 수 있는 장점을 가진다. 뿐 만 아니라 링크 상태가 좋지 않은 목적지 호스트로 향하는 패킷을 전송하지 않고 임시 FIFO 버퍼에 저장한 후에 나중에 전송함으로써, 기존의 방식에서 발생할 수 있는 HOL(Head Of Line) 블로킹 문제를 해결할 수 있다는 장점도 가진다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.354-357
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• 1996

Virtual Manufacturing System(VMS) is an integrated computer based model which has physical, logical schema and behavior of real manufacturing system. In this paper, an integrated scheduling system is developed to simulate and control a Virtual Factory. A workflow model is constructed to define and analyze the structure of a VMS. On-line dynamic dispatching system is developed using MultiPass algorithm and scheduling system considering dynamic CAPP is carried out. Integrated scheduling system developed in this paper reduces the discrepancies between virtual model and real manufacturing system, and control of real shop floor is possible.

• 대한전기학회논문지:전력기술부문A
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• 제53권10호
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• pp.573-580
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• 2004

A new real-time constrained dispatch scheduling (CDS) is needed for TWBP. The CDS needs to be performed at every dispatch period to decide generation power of scheduling generators and amounts of scheduling load. Therefore, the CDS is not based on real generation costs but on bidding data of market participants with some constraints such as power balance, generation limits, ancillary service, and transmission line limits. This paper selects linear programming(LP) as an optimization tool for the CDS and presents effective formulae for the LP application. This paper also presents the way of minimizing the number of variables and constraints of the LP to improve real-time applicability.

• 한국산업정보학회논문지
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• 제1권1호
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• pp.29-62
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• 1996

In this paper, the problem of determining cyclic schedules for a material handling hoist in the printed-circuit-board(PCB) electroplating line is considered. The objective of this research is to determine an optimal simple-cycle schedule of the hoist which in turn maximizes the line throughput rate. Previous approaches to the cyclic hoist scheduling problem are all mathematical programming-based approaches to develop cyclic schedules(Mixed Integer Programming, Linear Programming based Branch and Bound, Branch and Bound Search Method and so on). In this paper, a genetic algorithm-based approach for a single hoist scheduling in the PCB electroplating line is described. Through some experiments for the well known example data and randomly generated data, the proposed algorithm is shown to be more efficient than the previous mathematical programming-based algorithm.

• 대한산업공학회지
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• 제13권2호
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• pp.35-46
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• 1987

To minimize makespan for preemptive sequence dependent job scheduling with parallel identical processors, fundamental results, as the basis of new algorithm to be presented, such as McNauton's algorithm for independent jobs, Hu's characterization for dependent jobs, and Muntz-Coffman's algorithm, were first introduced. Then a huristic procedure was presented applying those concepts of zoning of assembly line balancing and of resource leveling on CPM network scheduling with two or more of parallel machines in general. New procedure has eliminated presumative machine assignment using ${\rho}$, rate of resource capability (${\rho}$ < 1), for practical scheduling.

• 산업경영시스템학회지
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• 제20권43호
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• pp.81-89
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• 1997

This study is concerned with the scheduling problems in flexible manufacturing systems(FMSs). The scheduling problem in FMSs is a complex one when the number of machines and jobs are increased. Thus, a heuristic method is recommended in order to gain near-optimal solutions in a practically acceptable time. The purpose of this study is to develope a machine and AGV dispatching algorithm. The proposed dispatching algorithm is a on-line scheduling algorithm considering the due date of parts and the status of the system in the scheduling process. In the new machine and AGV dispatching algorithm, a job priority is determined by LPT/LQS rules considering job tardiness. The proposed heuristic dispatching algorithm is evaluated by comparison with the existing dispatching rules such as LPT/LQS, SPT/LQS, EDD/LQS and MOD/LQS. The new dispatching algorithm is predominant to existing dispatching rules in 100 cases out of 100 for the mean tardiness and 89 cases out of 100 for the number of tardy jobs.

• 한국멀티미디어학회논문지
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• 제16권4호
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• pp.493-501
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• 2013

대규모 다중사용자용 온라인 게임 시스템의 당면 과제는 동시에 많은 사용자들에게 실시간적 응답 시간을 제공하는 것이다. 다수의 사용자들이 요청한 작업은 제한 시간 내에 응답이 제공되어야 하기 때문에 대규모 다중사용자용 온라인 게임 시스템은 일종의 연성 실시간 시스템이다. 클라이언트 이벤트들은 게임 세계의 본질에 따라 상이한 시간 요건과 일관성 요건을 가지고 있다. 이러한 요건들은 CPU 처리시 상이한 우선순위를 갖는 태스크들을 유발하게 된다. 이러한 태스크들의 시간적 요건을 충족하기 위하여 본 논문에서는 일시적 과부하가 발생한 경우 우선순위가 더 높은 태스크들에게 더 많은 CPU 대역폭을 우선적으로 할당하려는 우선순위 스케쥴링 기법들이 제시된다. 제시된 스케쥴링 기법은 우선순위가 높은 태스크일수록 종료시한 내에 성공적으로 종료되는 수를 최대화하며 종료시한이 경과된 이후 종료된 태스크들의 평균 지연시간을 최소화함으로써 대규모 다중사용자 온라인 게임 시스템의 실시간적 성능을 향상시킬 수 있다. 제시된 스케쥴링 기법의 성능은 다양한 시뮬레이션 실험을 통하여 측정되었다.

• 대한산업공학회지
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• 제38권4호
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• pp.262-275
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• 2012

This paper develops a multistage scheduling algorithm for the module operation of the LCD(Liquid Crystal Display) production systems and tests the efficiency of the proposed algorithm. The module operation is a multistage form composed of multiple sub operations of processes, and each stage is consists of multiple lines with the same kinds of machines. This paper presents a mathematical modeling reflecting the constraints of the LCD module operation and develops a multistage scheduling algorithm based on tabu search metaheuristic approach. For this purpose, an production order is assigned to a line of the sub operations and a sequence of the assigned order is rearranged to draw an efficient schedule. Simulation experiments test performance measures and show the efficiency of the proposed algorithm.