• 산업경영시스템학회지
• /
• 제32권3호
• /
• pp.110-117
• /
• 2009

This paper introduces a case study for efficient generation of production schedules in a tube manufacturing system. The considered scheduling problem consists of two sub problems : lot sizing for a job and Job sequencing. Since these problems require simulation optimization in which the performance measures are obtained by simulation execution, the trade-off between solution quality and computation time is an important issue. In this study, the optimal lot size for every product type is determined from simulation experiments. Then, target production quantity for each product type is transformed to several jobs such that a Job consists of determined lot size. To obtain the good solution for a Job sequence in a reasonable time, a number of alternatives are generated from heuristic rules developed by intuition and analysis of the considered system, and a job sequence is selected from simulation experiments.

• 대한안전경영과학회지
• /
• 제5권1호
• /
• pp.83-92
• /
• 2003

Scheduling plays an important role in shop floor planning. A scheduling shows the planned time when processing of a specific job will start on each machine that the job requires. It also indicates when the job will be completed on every process. Thus, it is a timetable for both jobs and machines. There is only one server available and arriving work require services from this server. Job are processed by the machine one at a time. The most common objective is to sequence jobs on the severs so as to minimize the penalty for being late, commonly called tardiness penalty. Based on other objectives, many criteria may serve as s basis for developing job schedules. The process also comprises all strategic planning, capital investments, management decisions, and tasks necessary to create a new product. manufacturing processes must be created so that the product can be produced in the product facility. Purchasing new equipment and training workers may be required if new technology is to be used. Tools, fixtures, and the sequence of steps in the manufacturing processes must all be developed to allow rapid, high-quality, cost effective production. Also, it may be needed to be rearrange the production facility to adapt to the new manufacturing processes. Therefore, this study tries to proposed that Scheduling by customer needs group for minimizing the problem and reducing inventory, product development time, cycle time, and order lead time.

• 한국사회복지학
• /
• 제60권4호
• /
• pp.55-77
• /
• 2008

본 연구는 근로빈곤층이 빈곤한 주요 원인이 이들이 노동시장에서 겪는 불안정한 경험이라는 점에 주목하여, 이들의 직업력이 어떻게 나타나는지 분석하였다. 이를 위해 사건배열분석과 최적일치법을 활용하여, 근로빈곤층의 직업력을 노동시장 진입 후 일한 기간, 직업 경력에서의 공백의 수와 그 기간, 거쳐 온 직업의 특성을 통해 총체적으로 이해하고자 하였다. 분석결과, 근로빈곤층은 비빈곤층과 비교할 때 일한 기간에서 통계적으로 유의미한 차이를 나타내지 않아 이들이 일을 적게 하기 때문에 빈곤한 것이 아니라는 것을 확인할 수 있었으며, 공백의 수와 기간, 직업의 특성을 통해 살펴본 결과 이들은 비빈곤층에 비해 불안정한 노동경험을 했다는 것을 확인할 수 있었다. 또한 남성과 여성 근로빈곤층 모두는 생애전반에 걸쳐 지속적으로 불안정한 노동경험을 했다는 것을 확인하였다. 이상의 결과를 바탕으로 근로빈곤층을 대상으로 하는 탈빈곤정책에 대해 제언하였다.

• 산업경영시스템학회지
• /
• 제13권21호
• /
• pp.91-100
• /
• 1990

This paper is concerned with the development of optimal algorithms for multi-stage flowshop scheduling problems with sequence dependent setup times. In the previous researches the setup time of a job is considered to be able to begin at the earliest opportunity given a particular sequence at the start of operations. In this paper the setup time of a job is considered to be able to begin only at the completion of that job on the previous machine to reflect the effects of the setup time to the performance measure of sequence dependent setup time flowshop scheduling. The results of the study consist of two areas; first, a general integer programming(IP) model is formulated and a nixed integer linear programming(MILP) model is also formulated by introducing a new binary variable. Second a depth-first branch and bound algorithm is developed. To reduce the computational burdens we use the best heuristic schedule developed by Choi(1989) as the first trial. The experiments for developed algorithm are designed for a 4$\times$3$\times$3 factorial design with 360 observations. The experimental factors are PS(ratio of processing time to setup time), M(number of machines), N(number of jobs).

• 대한안전경영과학회지
• /
• 제10권3호
• /
• pp.253-265
• /
• 2008

In this paper, we developed a heuristic algorithm to assign job to workers in parallel line inspection process without sequence. Objective of assigning job in inspection process is only to assign job to workers evenly. But this objective needs much time and effort since there are many cases in assigning job and cases increase geometrically if the number of job and worker increases. In order to solve this problem, we proposed heuristic algorithm to assign job to workers evenly. Experiments of assigning job are performed to evaluate performance of this heuristic algorithm. The result shows that heuristic algorithm can find the optimal solution to assign job to workers evenly in many type of cases. Especially, in case there are more than two optimal solutions, this heuristic algorithm can find the optimal solution with 98% accuracy.

• 한국산업융합학회 논문집
• /
• 제4권3호
• /
• pp.281-287
• /
• 2001

Traditional job shop scheduling is supposed that machine has a fixed processing job type. But actually the machine has a highly utilization or long processing time is occurred delay. Therefore product system is difficult to respond quickly to the change of products or loads or machine failure etc. Here we use flexible job shop which is supposed that a machine has several jobs by tool change. The heuristic for the flexible job shop scheduling has to solve two problems. One is a routing problem which is determine a machine to process job. The other is sequencing problem which is determine processing sequence. The approach to solve two problems arc a hierarchical approach which is determined routing and then schedule, and a concurrence approach which is solved concurrently two problems by considering routing when it is scheduled. In this study, we simulate for flexibility efficiency fo flexible job shop scheduling with machine failure using hierarchical approach.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제54권8호
• /
• pp.486-494
• /
• 2005

This paper presents a design experience of a supervisory control system. For effective programming of job commands, a petri net-type graphical language (PGL) is proposed applied to various tasks having concurrency and synchronization. Our PGL based supervisory control system is composed of PGL editor and PGL compiler; PGL editor is designed to help us to generate a job program using graphical symbols. PGL compiler includes analyzer, scheduler, and tranlator, PGL analyzer prevents a deadlock or resource allocation of unit cell, PGL scheduler generates a adequate job sequence of unit cell. and PGL translator translate the scheduled sequence into the iob program of each unit cell.

• 한국경영과학회지
• /
• 제26권2호
• /
• pp.69-83
• /
• 2001

The problem of minimizing total tardiness on a batch processing machine with incompatible job families when there are sequence independent setup times between families is studied where all jobs of the same family have identical processing times and jobs of different families cannot be processed together. A batch processing machine can process a number of jobs, within a maximal batch size, simultaneously as a batch. The processing time required of each batch is equal to the one of jobs. A dynamic programming algorithm which gives the optimal solution, and several heuristics are presented. Performance of simple dispatching rules based on due dates are compared, and the best of them is used as an initial solution for the decomposition algorithm, which is shown to give good schedules in relatively short computational time.

• 대한산업공학회지
• /
• 제9권1호
• /
• pp.23-31
• /
• 1983

A group scheduling problem, which is production scheduling problem associated with the concept of group technology, is studied under due date constraints in multi-stage manufacturing systems. The purpose of this paper is to develop and evaluate a practical heuristic procedure for determining group sequence and job sequence within each group to minimize total tardiness in multi-stage manufacturing systems. A heuristic algorithm has been developed by introducing the concept of relative measures of job tardiness and group tardiness for job sequencing and group sequencing, respectively. A numerical example is shown to illustrate the proposed procedure. The heuristic algoirthm is tested by comparisons with problems with known optimal solutions and also with random group schedules for a set of large-size problems. Results indicate that the proposed heuristic algorithm provides good solutions with small computational requirements, and thus is viable for large size problems in practice.

• 대한산업공학회지
• /
• 제27권2호
• /
• pp.158-168
• /
• 2001

We present a tabu search (TS) algorithm to minimize maximum lateness on a single machine in the presence of sequence dependent setup times and dynamic job arrivals. The TS algorithm starts with a feasible schedule generated by a modified ATCS (Apparent Tardiness Cost with Setups) rule, then through a series of search steps it improves the initial schedule. Results of extensive computational experiments show that the TS algorithm significantly outperforms a well-known RHP heuristic by Ovacik and Uzsoy, both on the solutions quality and the computation time. The performance advantage is particularly pronounced when there is high competition among jobs for machine capacity.