• Korean Journal of Construction Engineering and Management
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• v.7 no.1 s.29
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• pp.148-158
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• 2006

Public construction companies have strictly followed a rule that they should not do the works using water such as concrete pouring for the structural frame for a certain period during the winter season. It is usually known that the designated non-working period during the winter causes increase of the project duration and the project cost escalation. The halted work also makes negative effects on national economy because it reduces worker's income. However, the situation would be a lot better if the work for the structural frame is allowed under some conditions. The structural framework done alone without being followed by finish works gives a lot of stresses on the finish works. In this sense, this study examines how the structural framework performed during the winter season affect on the critical path of the finish works. To accomplish the objective of this research, the subnet for the finish works as well as a master network are prepared along with critical paths for a virtual construction site. Using the prepared networks, simulations are carried out to see the effects described above. This study is expected to be used in estimating the construction duration of high-rise apartment housing when the site work for the structural frame should be performed during this period.

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.595-602
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• 2018

Network-based scheduling methods can be classified into CPM method and PERT method. In the network scheduling chart, critical path can be estimated by performing the forward calculation and the backward calculation though the paths in the network chart. In PERT method, however, it is unreasonable to simply estimate the critical path by adding the sum of the activity durations in a specific path, since it does not incorporate probabilistic concept of PERT. The critical path of a PERT network can change according to the target period and deviation, and in some cases, the expected time of the critical path may not be the path with longest expected time. Based on this concept, this study proposes a technique to derive the most-likely critical path by comparing the sum of estimated time with the target time. It also proposes a method of systematically deriving all alternate paths for a network of repetitive activities. Case studies demonstrated that the most-likely critical path is not a fixed path and may vary according to the target period and standard deviation. It is expected that the proposed method of project duration forecasting will be useful in construction environment with varying target date situations.