• 대한안전경영과학회지
• /
• 제15권2호
• /
• pp.193-204
• /
• 2013

The growing logistics strategy of a company is to optimize their vehicle route scheduling in their supply chain system. It is very important to analyze for continuous pickups and delivery vehicle scheduling. This paper is a computational study to investigate the effectiveness of continuous pickups and delivery vehicle routing problems. These scheduling problems have 3 subproblems; Inbound Vehicle Routing Problem with Makespan and Pickup, Line-haul Network Problem, and Outbound Vehicle Routing Problem with Delivery. In this paper, we propose 5 heuristic Algorithms; Selecting Routing Node, Routing Scheduling, Determining Vehicle Type with Number and Quantity, and Modification Selecting Routing Node. We apply these Algorithms to S vehicle company. The results of computational experiments demonstrate that proposed methods perform well and have better solutions than other methods considering the basic time and due-date.

• 한국CDE학회논문집
• /
• 제18권3호
• /
• pp.224-233
• /
• 2013

For the scheduling and the job assignment of the ship hull production design which is a process-based work, we suggest the simulation-based scheduling using the discrete-event-based business process simulation. First, we analyze the ship hull production design process from the perspective of a job assignment to make it into the simulation model using DEVS (Discrete Event System Specification) which is the representative modeling method for a discrete-event simulation. Based on the APIs of the open-source discrete-event simulation engine, we implement the simulation using the Groovy script. We develop the scenario generator in which the user defines detail information of the construction drawing and its member blocks, and design engineers information, and the various setting for the simulation including the job assignment strategy. We use the XML files from this scenario generator as inputs of simulation so that we can get simulation result in forms of Gantt chart without changes of the simulation model.

• 대한산업공학회지
• /
• 제28권4호
• /
• pp.415-424
• /
• 2002

Semiconductor manufacturing has been emerged as a highly competitive but profitable business. Accordingly it becomes very important for semiconductor manufacturing companies to meet customer demands at the right time, in order to keep the leading edge in the world market. However, due-date oriented production is very difficult task because of the complex job flows with highly resource conflicts in fabrication shop called FAB. Due to its cyclic manufacturing feature of products, to be completed, a semiconductor product is processed repeatedly as many times as the number of the product manufacturing cycles in FAB, and FAB processes of individual manufacturing cycles are composed with similar but not identical unit processes. In this paper, we propose a production scheduling and control scheme that is designed specifically for semiconductor scheduling environment (FAB). The proposed scheme consists of three modules: simulation module, cycle due-date estimation module, and dispatching module. The fundamental idea of the scheduler is to introduce the due-date for each cycle of job, with which the complex job flows in FAB can be controlled through a simple scheduling rule such as the minimum slack rule, such that the customer due-dates are maximally satisfied. Through detailed simulation, the performance of a cycle due-date based scheduler has been verified.

• 산업경영시스템학회지
• /
• 제25권2호
• /
• pp.92-101
• /
• 2002

The Job Shop Scheduling Problem(JSSP) is concerned with schedule of m different machines and n jobs where each job consists of a chain of operations, each of which needs to be processed during an uninterrupted time period of a given length on a given machine. The purpose of this paper is to develop the efficient heuristic method for solving the minimum makespan problem of the large scale job shop scheduling. The proposed heuristic method is based on a Tabu Search(TS) and on a Constraint Satisfaction Technique(CST). In this paper, ILOG libraries is used to embody the job shop model, and a CST is developed for this model to generate the increased solution. Then, TS is employed to overcome the increased search time of CST on the increased problem size md to refine the next-current solution. Also, this paper presents the new way of finding neighbourhood solution using TS. On applying TS, a new way of finding neighbourhood solution is presented. Computational experiments on well known sets of MT and LA problem instances show that, in several cases, our approach yields better results than the other heuristic procedures discussed In literature.

• Journal of Electrical Engineering and Technology
• /
• 제3권2호
• /
• pp.199-206
• /
• 2008

The introduction of competition in electricity markets emphasizes the importance of sufficient transmission capacities to guarantee effective power transactions. Therefore, for the economic and stable electric power system operation, transmission security constrains should be incorporated into the dispatch scheduling problem. With the intent to solve this problem, we decompose a dispatch scheduling problem into a master problem(MP) and several subproblems(SPs) using Benders decomposition. The MP solves a general optimal power flow(OPF) problem while the SPs inspect the feasibility of OPF solution under respective transmission line contingencies. If a dispatch scheduling solution given by the MP violates transmission security constraints, then additional constraints corresponding to the violations are imposed to the MP. Through this iterative process between the MP and SPs, we derive an optimal dispatch schedule incorporating the post-contingency corrective rescheduling. In addition, we consider interruptible loads as active control variables since the interruptible loads can participate as generators in competitive electricity markets. Numerical examples demonstrate the efficiency of the proposed algorithm.

• 한국컴퓨터정보학회논문지
• /
• 제6권4호
• /
• pp.154-162
• /
• 2001

본 논문에서는 인터넷망에서 실시간 인터넷 서비스의 제공을 위해 라우터 시스템에 적용되는 다양한 스케줄링 알고리즘들을 분석하고 서비스 특성에 따라 지연 민감형 트래픽과 손실 민감형 트래픽의 QoS 요구사항을 보장할 수 있는 스케줄링 알고리즘을 제안한다. 이를 위하여, 먼저 ITU-T 권고안에 기초한 QoS 개념을 정의하고, 인터넷망에서의 패킷다중화기의 요구사항을 살펴보고 망에 적용하기 위해 고속의 패킷 포워딩 기능을 담당하는 패킷 다중화기의 기능 구조와, 입력 소스 트래픽의 QoS 등급에 기초하여 다양한 QoS를 만족시키기 위한 스케줄링 알고리즘을 설계한다. 마지막으로 모의 실험을 통해 패킷 손실율과 평균 지연 측면에서 알고리즘의 성능을 고찰한다.

• 한국컴퓨터정보학회논문지
• /
• 제26권9호
• /
• pp.213-221
• /
• 2021

본 연구에서는 학습자들이 다중 프로그래밍의 프로세스 스케줄링 정책 8가지를 잘 이해할 수 있도록 돕는 방법 중 하나로 시뮬레이션 앱을 개발하였다. 학습에서 시뮬레이션 형태의 앱은 실제와 유사한 환경을 제공해야 하며 학습자가 연습할 수 있도록 해야 한다. 이렇게 하기 위해 학습자들의 요구 사항을 조사 분석하고 학습자들의 이해를 중심으로 목적을 정하고, 설계하고 프로그래밍 하여, 8가지 스케줄링 정책을 시뮬레이션 할 수 있는 도구로서의 앱을 만들었고, 이것들이 잘 수행되고 있음을 보였다. 특히 지면 교재의 한계인 단계적 다양한 입력에 대한 단계적 다양한 도해와 그에 따른 설명을 갖지 못하는 문제를 이런 도구를 이용하여 해결할 수 있음을 보여주었다.

• Journal of applied mathematics & informatics
• /
• 제31권1_2호
• /
• pp.147-154
• /
• 2013

We analyze queueing model with priority scheduling by supplementary variable method. Customers are classified into two types (type-1 and type-2 ) according to their characteristics. Customers of each type arrive by independent Poisson processes, and all customers regardless of type have same general service time. The service order of each type is determined by the queue length of type-1 buffer. If the queue length of type-1 customer exceeds a threshold L, the service priority is given to the type-1 customer. Otherwise, the service priority is given to type-2 customer. Method of supplementary variable by remaining service time gives us information for queue length of two buffers. That is, we derive the differential difference equations for our queueing system. We obtain joint probability generating function for two queue lengths and the remaining service time. Also, the mean queue length of each buffer is derived.

• 대한전기학회논문지:전력기술부문A
• /
• 제54권3호
• /
• pp.152-157
• /
• 2005

An objected-oriented programming(OOP) technique is introduced to dispatch schedules for TWBP. Some dispatch schedules such as constrained (pre)dispatch, unconstrained (pre)dispatch, and nominal self-dispatch schedule need to be peformed to make power market work. These dispatch schedules are similar but have some differences in required constraints, needed data, and scheduling time. Therefore, it makes the scheduling program simple to introduce the OOP technique to this problem: to have each instance of the OOP perform its own dispatch scheduling. The developed program adopts linear programming(LP) as an optimization tool and could consider some crucial constraints such as power balance, generation power limits, generation ramp-rates, power limitations of transmission lines, and power system security.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.123-126
• /
• 1998

Generally, in a VOD(video on Demand) system, batching technique is oten used to improve throughput. Since subscribers to VOD servives tend to withdraw their requests as the latency becomes large, an optimal scheduling scheme should consider not only batching size but also withdrawal rae, service latency and fairness between different programs. In this paper, we propose a new scheduling scheme, which shows improvement in fairness and reduction in withdrawal rate and service latency compared with other well known schemes. When there are 2 or more streams are available in the VOD server, proposed scheme apply different program selection policies to each streams. Using this approach effectiveness of stream usage can be improved.