• Title/Summary/Keyword: Rework

Search Result 137, Processing Time 0.029 seconds

Quantitative Analysis of Magnitude of Rework by Project Types and Sources of Rework

  • Hwang, Bon-Gang
    • Korean Journal of Construction Engineering and Management
    • /
    • v.7 no.6
    • /
    • pp.202-211
    • /
    • 2006
  • Rework in the construction industry can adversely affect project cost and schedule performance. Based on direct rework costs recorded on 359 construction projects, this paper presents an assessment of the magnitude of rework by various types of projects and sources of rework. The results from this paper establish that on average 4.5% and 2.5% of actual construction costs were spent on rework for owner and contractor projects, respectively. Furthermore, this paper determines that the direct rework costs differ by project types and sources of rework. Finally, it permits the development of rework reduction initiatives. By quantifying and recognizing the different magnitude of rework, the industry can be aware of the waste from rework and develop effective plans for managing rework, ultimately improving project cost performance.

A Study of Strategy for Planning of Rework in Semiconductor Monitoring Burn-in Test Process (반도체 MBT 공정의 Rework 제품 투입결정에 관한 연구)

  • Lee, Do-Hoon;Ko, Hyo-Heon;Kim, Sung-Shick
    • IE interfaces
    • /
    • v.18 no.3
    • /
    • pp.350-360
    • /
    • 2005
  • This paper considers a strategy for planning of rework in semiconductor monitoring burn-in test process. The equipment error in monitoring burn-in test process generates many defects. These defects are transformed into good products by rework process, i.e. retest. Rework has the advantage of saving production costs. But rework increases holding costs and incurs rework costs. In monitoring burn-in test process, rework depends on operator's experience with no pre-defined specification. In practice, a number of rework activities are performed with respect to the product importance and inventory quantity. Moreover, disregard for order jobs schedule have caused due date penalties. So a strategy for planning of rework by which order jobs schedule are not affected is suggested. Futhermore, production costs, rework costs and inventory costs for planning of rework are considered.

A Study of Rework Strategies in Semiconductor Monitoring Burn-in Test Process (반도체 MBT 공정의 Rework 제품 투입결정에 관한 연구)

  • 이도훈;고효헌;김성식
    • Proceedings of the Korean Operations and Management Science Society Conference
    • /
    • 2004.10a
    • /
    • pp.603-606
    • /
    • 2004
  • 본 연구는 반도체 검사공정 중의 하나인 MBT 공정의 Rework 투입정책에 관한 연구이다. MBT 공정에서는 제품의 신뢰성과는 상관없이 설비오류로 인한 불량품이 다량으로 발생한다. 이러한 불량품을 MBT 공정의 재검사 작업인 Rework을 통해 양품으로 전환하게 된다. MBT 공정의 Rework은 FAB 공정 이후의 많은 공정을 거치지 않고 단일공정 진행으로 새로운 양품을 얻을 수 있는 이점을 가진다. 반면에 Rework 비용 및 공정재고비용이 발생하는 특징이 있다. 현재 MBT 공정의 Rework 작업은 정해진 규칙 없이 작업자 경험에 의존하여 진행하며, 제품의 중요도 및 재고량에 따라 투입이 정해진다. 또한 주문 작업의 투입일정과 납기를 고려하지 않은 Rework 작업으로 인해 납기차질이 발생하기도 한다. 본 연구에서는 Rework 작업이 생산계획에 영향을 주지 않는 범위 안에서의 투입계획을 제안한다. 또한 MBT 공정의 Rework 이익인 제조원가 절감이익과 비용인 Rework 비용, 재고비용을 고려한 Rework 제품 투입정책을 제안한다.

  • PDF

Quantitative Analysis of Work Type's Rework Cost in Construction Project (건설공사 공종별 재작업 비용의 정량적 분석)

  • Chi, Sung-Joon;Park, Jung-Eun;Cha, Yong-Woon;Han, Sangwon
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2016.05a
    • /
    • pp.237-238
    • /
    • 2016
  • Rework is a major cause that adversely affects the performance of a construction project, such as schedule delay or cost overrun. In order to prevent rework, research has been mainly conducted to analyze the cause of rework, but limited to quantitatively measure cost of rework and analyze its impact on project performance. Therefore, this paper aims to analyze impact of rework cost using 369 rework items collected from 3 construction site. This research is expected to accurately determine control target of rework and to improve efficiency of business operations in construction project.

  • PDF

Comparative Analysis of Rework Policies in Multistage Production System (다단계 생산시스템에서 재작업정책의 비교분석)

  • Shin, Jaeseon;Han, Jooyun;Jeong, Bongju
    • Journal of Korean Institute of Industrial Engineers
    • /
    • v.32 no.1
    • /
    • pp.29-41
    • /
    • 2006
  • As the quality and environmental problems become one of the most concerned issues of company, the rework policy needs to be efficiently designed and implemented to sustain the company's competitiveness. This paper examines three basic rework policies in multi-stage production systems and analyzes them in terms of costs of setup, production, inspection, and inventory. For analyzing the performance of the rework policies, we propose mathematical models which can compute total production cost and determine the optimal production batch size to minimize the total production cost. The rework policies are classified by the number and location of inspection stages. Using the mathematical models, we could analyze the performances of rework policies and suggest the optimal rework policy according to each manufacturing environment. The analyses show that the proposed model can be used to analytically evaluate and choose the rework policies.

Design and Planning Process Management for Reducing Rework in Modular Construction Using Dependency Structure Matrix (DSM) (DSM을 활용한 모듈러 건축 설계단계에서의 제작 및 시공 정보 반영 및 재시공 감소 방안)

  • Hyun, Hosang;Lee, Hyun-soo;Lee, Jeonghoon;Park, Moonseo
    • Journal of the Architectural Institute of Korea Structure & Construction
    • /
    • v.35 no.2
    • /
    • pp.29-36
    • /
    • 2019
  • Modular construction has benefits such as short construction duration and high productivity owing to the production in factory and owing to simultaneous on-site work. However, rework occurs in modular construction and the rework affects the efficiency of modular construction. The almost of causes of rework are exist in design process. To reduce the cause of rework, the information flow of the design process should be managed and the plan to reduce rework should be included. However, the modular construction has complex process because of impeded unit production so it is hard to manage the information flow in design process. Moreover, when the plan to reduce rework is included, the design process will be more complicated. Therefore, the objective of this research is to suggest the design process including the rework reduction plan and to alleviate the complexity of design process by using Dependency Structure Matrix(DSM). By using DSM, the iteration and feedback in design process is reduced and it can be expected that rework in modular project can be reduced by using suggested design process.

Problem space based search algorithm for manufacturing process with rework probabilities affecting product quality and tardiness (Rework 확률이 제품의 품질과 납기준수에 영향을 주는 공정을 위한 문제공간기반 탐색 알고리즘)

  • Kang, Yong-Ha;Lee, Young-Sup;Shin, Hyun-Joon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.10 no.7
    • /
    • pp.1702-1710
    • /
    • 2009
  • In this paper, we propose a problem space based search(PSBS) algorithm to solve parallel machine scheduling problem considering rework probabilities. For each pair of a machine and a job type, rework probability of each job on a machine can be known through historical data acquisition. Neighborhoods are generated by perturbing four problem data vectors (processing times, due dates, setup times, and rework probabilities) and evaluated through the efficient dispatching heuristic (EDDR). The proposed algorithm is measured by maximum lateness and the number of reworked jobs. We show that the PSBS algorithm is considerably improved from the result obtained by EDDR.

Scheduling Algorithm for Nonidentical Parallel Machines Problem with Rework (Rework가 존재하는 이종병렬기계에서의 일정계획 수립)

  • Kang, Yong Ha;Kim, Sung Shick;Park, Jong Hyuck;Shin, Hyun Joon
    • Journal of Korean Institute of Industrial Engineers
    • /
    • v.33 no.3
    • /
    • pp.329-338
    • /
    • 2007
  • This paper presents a dispatching algorithm for nonidentical parallel machines problem considering rework, sequence dependent setup times and release times. For each pair of a machine and a job type, rework probability of each job on a machine can be known through historical data acquisition. The heuristic scheduling scheme named by EDDR (Earliest Due Date with Rework probability) algorithm is proposed in this paper making use of the rework probability. The proposed dispatching algorithm is measured by two objective function value: 1) total tardiness and 2) the number of reworked jobs, respectively. The extensive computational results show that the proposed algorithm gives very efficient schedules superior to the existing dispatching algorithms.

Economic Manufacturing Quantity Models with Rework and Disposal (재작업과 폐기가 수반되는 경제적 생산량 모형)

  • Sohn, Kwon-Ik
    • Journal of Industrial Technology
    • /
    • v.36
    • /
    • pp.23-31
    • /
    • 2016
  • This paper presents EMQ models in which some proportion of defective items are produced and some of them are converted to good items through rework process and items not converted are disposed. Numerical models are developed for three cases of disposal and optimal solution of each model is derived. In the first model, if a defective item is found during the production process, only re-workable items are stored and reworked after normal production is finished. Not re-workable items are disposed immediately during normal production. The second model deals with the case where all defective items are stored and items to be disposed are determined in rework process. In the third model, an additional inspection process exists before rework to determine rework or disposal. Numerical examples are presented to validate the proposed models.

  • PDF

Adaptive scheduling algorithm for manufacturing process with nonstationary rework probabilities using reinforcement learning (강화학습을 이용한 비안정적인 Rework 확률이 존재하는 제조공정의 적응형 스케줄링 알고리즘)

  • Shin, Hyun-Joon;Ru, Jae-Pil;Lee, Jae-Woo
    • Proceedings of the KAIS Fall Conference
    • /
    • 2010.05b
    • /
    • pp.1180-1180
    • /
    • 2010
  • 본 연구는 비안정적인 rework 발생 확률 자체가 납기 및 제품 품질에 매우 나쁜 영향을 미치는 복잡한 제조공정을 대상으로 rework 발생 확률의 변화에 따라 작업의 투입정책(dispatching policy)을 동적으로 변화시킬 수 있는 스케줄링 기법을 제안한다. 본 연구에서는 강화학습(reinforcement learning) 기법을 이용하여 시간의 흐름에 따라 변화하는 rework 발생 확률을 기반으로 작업 투입정책의 모수를 동적으로 조정함으로써 효율적인 투입계획을 수립하는 적응형 스케줄링 알고리즘을 제안하고, 다양한 현실적인 시나리오를 개발하여 그 성능을 테스트한다.

  • PDF