• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.27 no.1
• /
• pp.47-50
• /
• 2004

This paper deals with the problem of batching and scheduling of jobs whose processing times are different respectively But, they are given as not the exact value but the range from the lower limits to the upper, which makes it possible to group jobs into batches. The grouping of jobs is desirable because of the capability of the batch processor to accommodate several jobs at once. The time required to process the jobs in any batch depends on their lower limit processing times. Once processing is initiated on a batch processor, the batch cannot be interrupted, nor can other jobs be started. And all jobs are assumed to be simultaneously available. This paper develops the model to describe these situation and a heuristic method to minimize its total tardiness.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 1998.10a
• /
• pp.731-740
• /
• 1998

This paper discusses a brcriterion approachto sequencing with time/cost trade-offs. The first problem is to minimize the total flow time and the maximum tardiness. And second is to the maximum tardiness and resource allocation costs. This approach , which produces an efficient frontier of possible schedules, has the advantage that it does not require the sequencing criteria to be measurable in the same units as the resource allocation cost. The basic single machine model is used to treat a class of problems in which the sequencing objective is to minimize the maximum completion penalty. It is further assumed that resource allocation costs can be represented by linear time/cost function.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2005.05a
• /
• pp.517-522
• /
• 2005

This paper addresses scheduling heuristics for an assembly job-shop that includes at least an assembly process throughout its processes. The assembly job shop has certain characteristics not only considering the precedence relationship between the processes but also considering the processing progress between the parts. In addition, it probably presents a different processing time for the same product according to the order of processes and the point of workable time, due to the difference in the availability of equipments. The paper proposes several priority-based dispatching rules that consider these characteristics of the assembly job-shop, aiming to minimize the total tardiness of products in the shop floor. Computational tests showed that job due date based priority rules significantly outperform existing priority rules in terms of total tardiness.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.23 no.1
• /
• pp.29-41
• /
• 1998

This paper addresses the problem of scheduling a set of jobs with a common due data on a single machine. The objective is to minimize the sum of the earliness and tardiness of jobs subject to $T_{max}{\le}{\Delta}\;for{\Delta}{\ge}0$. Properties for the $MAD/T_{max}$ problem are found and the problem is shown to be NP-complete in the ordinary sense. According to the range of Δ, the problem can be solved in polynomial time. Also, some special cases where an optimal schedule is found in polynomial time are discussed.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1994.04a
• /
• pp.357-363
• /
• 1994

In many industrial situations the human acts as the primary scheduler since there often exist various constraints and considerations that may not be mathematically or quantitatively defined. For proper design of interactive scheduling systems, how human strategy and performance are affected by the fashion of human-computer interaction at various levels of task complexity should be investigated. In this study, two scheduling experiments were conducted. The first one showed that human schedulers could perform better than simple heuristic rules with each of typical performance measures such as average machine utilization, average tardiness, and maximum tardiness. In experiment 2, the effect of providing computer-generated initial solution was investigated. The results was that in complex problems the subjects performed significantly better when the initial solutions were generated by themselves, evidencing the importance of the continuity of strategic search through the problem.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2000.04a
• /
• pp.90-93
• /
• 2000

This paper presents job scheduling for non-identical parallel machines using Simulated Annealing (SA). The scheduling problem accounts for allotting work parts of L lots into M parallel machines, where each lot is composed of N homogeneous jobs. Some lots may have different jobs while every job within each lot has common due date. Each machine has its own performance and set up time according to the features of the machine, and also by job types. A meta-heuristic, SA, is applied in this study to determine the job sequences of the scheduling problem so as to minimize total tardiness of due. The SA method is compared with a conventional steepest descent(SD) algorithm that is a typical tool for finding local optimum. The comparison shows the SA is much better than the SD in terms tardiness while SA takes longer , but acceptable time.

• Journal of Korean Institute of Industrial Engineers
• /
• v.26 no.2
• /
• pp.183-192
• /
• 2000

This paper considers the problem of scheduling a set of n jobs on m parallel machines to minimize total weighted tardiness. For the problem a genetic algorithm is proposed, in which solutions are encoded using the random key method suggested by Bean and new crossover operators are employed to increase performance of the algorithm. The algorithm is compared with the Modified Due-Date (MDD) algorithm after series of tests to find appropriate values for genetic parameters. Results of computational tests on randomly generated test problems show that the suggested algorithm performs better than the MDD algorithm and gives good solutions in a reasonable amount of computation time.

• Journal of the Korea Safety Management & Science
• /
• v.8 no.4
• /
• pp.195-204
• /
• 2006

This paper deals with a batch processor model in which the batch processing speed depends on the jobs assigned to the batch. Each job is completed by accomplishing its required job processing quantity which is calculated as job speed product processing time. Its speed is given as not the exact value but the range. Thus the batch sets are constructed by the jobs which hold the speed in common. And the batch sets are processed as soon as possible. We developed the model to described the problem situation and adopt the total tardiness as the decision criterion.

• Journal of the Korea Safety Management & Science
• /
• v.13 no.4
• /
• pp.125-137
• /
• 2011

Customers are generally requiring a variety of products, earlier due date, and lower price. A manufacturing process needs the efficient scheduling to meet those customer's requirements. This study proposes the novel algorithm named MJA(Minimum Job completion time and AGV time) that increases the performance of machines and AGV(Automated Guided Vehicles) in many kinds of job types. MJA optimizes the bottleneck of machines and efficiency of AGV with considering two types of dispatching at the same time. Suggested algorithm was compared with existing heuristic methods by several simulations, it performed better for reducing the time of tardiness.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.28 no.1
• /
• pp.92-96
• /
• 2005

This paper deals with a batch processor model in which the batch processing times depend on the jobs assigned to the batch. Each job has a distinct processing time which is determined as not the exact value but the range from the lower limit to the upper, which makes it possible to group several jobs into the same batch. In point of this flexibility our model can be referred to as the generalization of the bum-in model in which the upper limit of each job is unbounded. The jobs to be scheduled may be available nonsimultaneously. Therefore they have different ready times. We develop the model to describe the problem situation and the heuristic methods to minimize the total tardiness. And our batching rule is compared with other dispatching ones.