• 한국건설관리학회논문집
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• 제7권6호
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• pp.202-211
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• 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.

• 산업공학
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• 제18권3호
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• pp.350-360
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• 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.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2004년도 추계학술대회 및 정기총회
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• pp.603-606
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• 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.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.237-238
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• 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.

• 대한산업공학회지
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• 제32권1호
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• pp.29-41
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• 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.

• 대한건축학회논문집:구조계
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• 제35권2호
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• pp.29-36
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• 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.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1702-1710
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• 2009

본 논문은 rework 발생확률을 고려하는 병렬기계 스케줄링 문제를 위해 문제공간기반 탐색 알고리즘을 제안한다. 각 기계와 작업유형별로 rework 발생확률이 존재하며 이것은 자동화된 공정에서 과거데이터로부터 산출가능하다. 스케줄링 문제의 데이터 벡터 (가공시간, 납기, 셋업시간, rework확률)를 교란시킴으로써 이웃해를 생성하고 이로부터 도출된 해는 EDDR이라는 효과적인 휴리스틱을 이용하여 평가한다. 제안된 알고리즘은 납기지연의 최대값과 rewok 발생 작업수로 평가함으로써 제품의 품질과 납기수준을 동시에 고려할 수 있도록 한다.

• 대한산업공학회지
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• 제33권3호
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• pp.329-338
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• 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.

• 산업기술연구
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• 제36권
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• pp.23-31
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• 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.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 2부
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• pp.1180-1180
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• 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.