• Title/Summary/Keyword: Job sequence

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A study on algorithms to minimize makespan of sequence-dependent jobs (작업준비시간을 고려한 총작업완료시간 최소화 해법에 관한 연구)

  • 안상형
    • Korean Management Science Review
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    • v.12 no.2
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    • pp.77-87
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    • 1995
  • In this paper we develop an efficient heuristic algorithm for the problem of scheduling n sequence-dependent jobs on a basic processor to minimize makespan. Efficient solution methods are already known for the sequence- independent case. But for the sequence-dependent case, this problem belongs to a set of strong NP-complete problems. We present a heuristic which is similar to shortest setup time heuristic but opportunity cost of setup time rather than shortest setup time is used for choosing next job. This heuristic algorithm has same computational complexity and worst case ratio as the shortest setup time heuristic. We used Wilcoxon signed rank test to show that our heuristic is superior to nearest setup time heuristic in term of average behavior.

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A Genetic Algorithm for Scheduling Sequence-Dependant Jobs on Parallel Identical Machines (병렬의 동일기계에서 처리되는 순서의존적인 작업들의 스케쥴링을 위한 유전알고리즘)

  • Lee, Moon-Kyu;Lee, Seung-Joo
    • Journal of Korean Institute of Industrial Engineers
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    • v.25 no.3
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    • pp.360-368
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    • 1999
  • We consider the problem of scheduling n jobs with sequence-dependent processing times on a set of parallel-identical machines. The processing time of each job consists of a pure processing time and a sequence-dependent setup time. The objective is to maximize the total remaining machine available time which can be used for other tasks. For the problem, a hybrid genetic algorithm is proposed. The algorithm combines a genetic algorithm for global search and a heuristic for local optimization to improve the speed of evolution convergence. The genetic operators are developed such that parallel machines can be handled in an efficient and effective way. For local optimization, the adjacent pairwise interchange method is used. The proposed hybrid genetic algorithm is compared with two heuristics, the nearest setup time method and the maximum penalty method. Computational results for a series of randomly generated problems demonstrate that the proposed algorithm outperforms the two heuristics.

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Group Scheduling Problem in Multi - Stage Manufacturing Systems with Dependent Setup time (준비시간(準備時間)이 종속인 다단계(多段階) 생산(生産) 시스템의 집단일정계획(集団日程計劃))

  • No, In-Gyu;Nam, Hui-Yeol
    • Journal of Korean Institute of Industrial Engineers
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    • v.12 no.2
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    • pp.33-44
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    • 1986
  • This research is concerned with group scheduling problems in multi-stage manufacturing system with dependent setup time. The objective of the research is to develop and evaluate a heuristic algorithm for determining group sequence and job sequence within each group to minimize total tardiness in multi-stage manufacturing systems with sequence dependent group setup time. The group scheduling heuristic algorithm is developed and evaluated by comparisons with twenty-seven problems with the known optimum solutions and 144,000 random schedules of a large variety problems. The results indicate that the proposed heuristic algorithm gets the same optimum solutions for the problems and also provides the good solutions in comparison with the random schedules of the large variety problems. A numerical example is given to illustrate the heuristic algorithm.

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A Constrained Single Machine Scheduling Model with Earliness/Tardiness and Flow Time Measures

  • Joo, Un-Gi;Sung, Chang-Sup
    • Journal of the Korean Operations Research and Management Science Society
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    • v.20 no.1
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    • pp.115-130
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    • 1995
  • This paper considers a single machine nonpreemptive scheduling problem with a given common due date. In the problem, the optimal job sequence is sought to minimize the sum of earliness/tardiness and flow time measures in the situation where all jobs are available at time zero, and weights per unit length of earliness/tardiness and flow time are V and W, respectively. Some dominant solution properties are characterized to deriva both an optimal starting time for an arbitrary sequence and sequence improvement rules. The optimal schedule is found to the case W .geq. V/. By the way, it is difficult to find the optimal schedule for the case W < V. Therefore, the derived properties are put on together to construct a heuristic solution algorithm for the case W < V, and its effectiveness is rated at the mean relative error of about 3% on randomly generated numerical problems.

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A Note on the Minimization of the Expected Makespan and the Expected Flow Time in M Machine Flow Shops with Blocking

  • Wie Sung Hwan
    • Journal of the military operations research society of Korea
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    • v.10 no.2
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    • pp.75-83
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    • 1984
  • Consider an m machine flow shop with blocking. The processing time of job j,j=1,..., n on each one of the m machines is equal to the same random variable $X_j$ and is distributed according to $F_i$. We assume that the processing times are stochastically ordered, i.e., $F_{1_{-st}}{<}F_{2_{st}}{<}cdots_{-st}{<}F_n$. We show that the sequence 1,3,5,...,n-1,n,n-2,...,6,4,2 when n is even and sequence 1,3,5,...,n-2,n,n-1 ... 6,4,2 when n is odd minimizes the expected makespan and that the sequence 1,...,n minimizes the expected flow time.

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On the Multi-Stage Group Scheduling with Dependent Setup Time (종속적 준비시간을 갖는 다단계 그룹가공 생산시스템에서의 그룹스케듈링에 관한 연구)

  • 황문영
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.17 no.31
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    • pp.115-123
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    • 1994
  • Group scheduling, which is a kind of operations scheduling based on the GT concept is analyzed in a multi-stage manufacturing system. The purpose of this research is to develop and evaluate a heuristic algorithm for determining gro up sequence and job sequence within each group to minimize a complex cost function, i.e. the sum of the total pe-nalty cost for tardiness and the total holding cost for flow time, in a multi-stage manufacturing system with group setup time dependent upon group sequence. A heuristic algorithm for group sc heduling is developed, and a numerical example is illustrated. For the evaluation of the pro-posed heuristic algorithm, the heuristic solution of each of 63 problems is compared with that of random scheduling. The result shows that the proposed heuristic algorithm provides better solution in light of the proposed cost function.

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Dynamic Programming Algorithms for Scheduling Jobs with Sequence-Dependent Processing Times (순서 의존적인 작업시간을 갖는 작업들의 스케쥴링을 위한 동적계획법)

  • Lee, Moon-Kyu;Lee, Seung-Joo
    • Journal of Korean Institute of Industrial Engineers
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    • v.24 no.3
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    • pp.431-446
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    • 1998
  • In this paper, we consider the problem of scheduling n jobs with sequence-dependent processing times on a set of parallel-identical machines. The processing time of each job consists of a pure processing time and a sequence-dependent setup time. The objective is to maximize the total remaining machine available time which can be used for other tasks. For the problem, we first propose a dynamic programming(DP) algorithm for sequencing jobs processed on a single machine. The algorithm is then extended to handle jobs on parallel-identical machines. Finally, we developed an improved version of the algorithm which generates optimal solutions using much smaller amount of memory space and computing time. Computational results are provided to illustrate the performance of the DP algorithms.

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Sequence Analysis in Women's Work Transition (여성취업이행 경로의 생애과정 씨퀀스(sequence) 분석)

  • 은기수;박수미
    • Korea journal of population studies
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    • v.25 no.2
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    • pp.107-138
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    • 2002
  • In general, women's labor force participation follows a M-curve pattern because women's state of economic activity usually changes by their life course stage. This research attentions that the effect of sequence of life course as well as the effects of‘marriage bar’, or‘maternity leave’is very important in understanding women's chaning economic activity status. First, this research hypothesizes that women's four patterns of job career such as‘continuous pattern’,‘discontinuous pattern’,‘non-economic activity pattern’,‘marriage leave pattern’result a significant difference in social and demographic variables. Second, this research analyzes the effect of ordering and timing of life events on women's work transition. This research investigates labor market dynamics to conceptualize labor market behaviors using longitudinal data and sequence analysis and event history analysis. We find that four patterns of job career vary by age, educational attainment, having a certificate or not, their parents’human capital and health status. And we find that the ordering and timing of‘participation in labor market’and‘marriage’determine the pattern of women's work transition.

The Estimation of the Demand Function of Pork Cuts (돼지고기 부위별 수요함수 추정 - 수도권 소비자를 중심으로 -)

  • Nam, Kuk-Hyun;Choe, Young-Chan
    • Journal of Agricultural Extension & Community Development
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    • v.23 no.1
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    • pp.27-37
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    • 2016
  • This paper estimated the demand function of the cuts of pork by using the consumer panel and the weather data from the Korea Meteorological Administration with a log-log model and AIDS model. The results show that the price elasticity of demand for cuts of pork is high in the sequence of arm shoulder, leg, special cuts, tenderloin, blade shoulder. In contrast, spare rib, belly and loin are classified as low price elasticity of demand. The income elasticities of demand for leg and blade shoulder are 11% and 7.6% respectively. The loin is classified as inferior goods, because demand decreases when income increases. The results also demonstrate show that the demand increases highly in the sequence of loin, arm shoulder, spare rib, belly if housewife is older, and the demand of belly increases when family number increases. Belly substitutes every cut except spare rib, and tenderloin substitutes special cuts. Spare rib, on the other hand, does not substitute other cuts. In addition, job status, family member, husband job, purchasing place, consumer characteristic, eating-out times, purchasing time, and weather are statistically significant.

A Scheduling Problem to Minimize Total Tardiness in the Two-stage Assembly-type Flowshop (총 납기지연시간 최소화를 위한 두 단계 조립시스템에서의 일정계획에 관한 연구)

  • Ha, Gui-Ryong;Lee, Ik-Sun;Yoon, Sang-Hum
    • Journal of the Korean Operations Research and Management Science Society
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    • v.33 no.3
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    • pp.1-16
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    • 2008
  • This paper considers a scheduling problem to minimize the total tardiness in the two-stage assembly-type flowshop. The system is composed of multiple fabrication machines in the first stage and a final-assembly machine in the second stage. Each job consists of multiple tasks, each task is performed on the fabrication machine specified in advance. After all the tasks of a job are finished, the assembly task can be started on the final-assembly machine. The completion time of a job is the time that the assembly task for the job is completed. The objective of this paper is to find the optimal schedule minimizing the total tardiness of a group of jobs. In the problem analysis, we first derive three solution properties to determine the sequence between two consecutive jobs. Moreover, two lower objective bounds are derived and tested along with the derived properties within a branch-and-bound scheme. Two efficient heuristic algorithms are also developed. The overall performances of the proposed properties, branch-and-bound and heuristic algorithms are evaluated through numerical experiments.