• International conference on construction engineering and project management
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• 2015.10a
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• pp.604-605
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• 2015

To secure quality of dam construction needs appropriate construction duration. Tight construction schedule may have negative influence on infrastructure quality, work safety and maintenance cost. It is necessary to reflect proper construction duration in the planning phase. There have been standards for estimating construction duration of building and industrial complex development but dam construction have not. In order to estimate construction duration of CFRD, feasible study reports and design reports were analyzed to acquire available information. After that, considering on construction duration methods such as comparison with similar cases, approximate estimating formula, approximate quantity assumption were adapted to Critical Path items. Hence, this study present framework for construction duration estimating of CFRD in the planning phase. This framework can be applied other types of dam along the same line.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.4
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• pp.59-64
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• 2018

Construction schedule acceleration due to unreasonable construction planning frequently leads to construction accidents. In order to avoid such inevitable acceleration and to ensure safety in construction sites, there is a need for objective standards to determine appropriate construction duration for each construction process earlier in the process. In order to achieve the goal, intensive experts interviews were firstly conducted to identify candidate drivers affecting construction schedule of road tunnel excavation works. Then, a total of 34 field data was collected from on-going sites to analyze. It was found that actual excavation length per one day on site is varied mostly by Rock Mass Rating(RMR) types from various statistical analyses. Therefore an one-way table of excavation length per a day by RMR types were presented in a form of percentile. The results will help industry experts determine the most appropriate construction schedule for the works, which eventually lead to a zero accident site in many ways.

• Journal of the Korea Institute of Building Construction
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• v.11 no.5
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• pp.523-529
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• 2011

In a tall building construction with reinforced concrete structures, the selection of an appropriate formwork system is a crucial factor for the success of the project. Thus, selecting an appropriate formwork system affects the entire construction duration and cost, as well as subsequent construction activities. However, in practice, the selection of an appropriate formwork system has depended mainly on the intuitive and subjective opinion of working level employees with restricted experience. Therefore, in this study, a formwork system selection model using the Adaboost algorithm is proposed to support the selection of a formwork system that is suitable for the construction site conditions. To validate the applicability of the proposed model, the selection models Adaboost and ANN were both applied to actual case data of tall building construction in Korea. The Adaboost model showed slightly better accuracy than that of the ANN model. The Adaboost model can assist engineers to determine the appropriate formwork system at the inception of future projects.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.601-608
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• 2021

Recently, despite a decrease in the number of working days and an increase in the number of non-working days due to an increase in the abnormal climate and the revision of the Labor Standards Act, a standard construction period reflecting this has not been established. For this reason, even if the appropriate construction period is calculated at the site, there is a situation where delays occur due to unexpected circumstances. Therefore, this study proposes a method of calculating the number of non-working days for railway bridgework construction that reflects changes in construction conditions and climate change and reflects this to railway bridgework construction, and the number of working days was calculated. As a result, the number of non-working days by region and month in Korea was derived, and through this, the necessity of regulations and standards for appropriate construction periods reflecting regional characteristics and characteristics of each construction type was presented.

• Journal of the Korea Institute of Building Construction
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• v.11 no.2
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• pp.100-107
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• 2011

As construction duration significantly influences the performance and the success of construction projects, it is necessary to appropriately manage the impact factors affecting construction duration. Recently, interest in the construction industry has been rising due to the recent change in the construction legal system, and the competition among the construction companies on construction time. However, the impact factors are extremely diverse. The existing productivity data on impact factors is not sufficient to properly identify the impact factor and measure the productivity from various perspectives, such as subcontractor, time, crew, work and so on. In this respect, a multidimensional analysis by a data warehouse is very helpful in order to view the manner in which productivity is affected by impact factors from various perspectives. Therefore, this research proposes a method that effectively takes the diverse productivity data of impact factors, and generates a multidimensional analysis. Decision tree analysis, a data mining technique, is also applied in this research in order to supply construction managers with appropriate productivity data on impact factors during the construction management process.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.89-97
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• 2015

This paper analyzes the duration of the construction document (CD) phase of 42 large public building projects delivered by the total solution service of Public Procurement Services in Korea from 2009 to 2014. The quality of construction documents significantly affects the quality of construction and facility management. Thus, securing appropriate time for the CD phase during project planning is important for the quality of a project. Currently, the duration of the CD phase is planned based on the construction costs of a project following a notice of the Ministry of Land, Infrastructure and Transport. However, our analysis results showed that the correlation between the actual duration of the CD phase and construction costs is very weak. The actual CD phase takes 1.33-1.79 times longer than the planned duration. The practitioners who were interviewed, were already aware that the correlation between the duration of the CD phase and the construction costs is weak. They identified the complexity of the project, the extent of the design changes, project type, client characteristics, and others as more influential factors on the CD phase than the construction costs. To improve the quality of CDs, a new guideline for determining an adequate CD phase duration should be studied and developed.

• Land and Housing Review
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• v.8 no.3
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• pp.189-200
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• 2017

The work breakdown structure and the precedence relations by work activity are very important because they are the basic data for estimating the construction duration in the construction work. However, there is no standard to accurately estimate the construction duration since the size of the school facilities construction is smaller than the general construction work. Therefore, some schools are unable to open in March or September and the delay of the construction duration can cause damage to the students. To solve this problem, this study developed a work breakdown structure of school facilities construction work and analyzed the precedence relations by work activities. The work breakdown structure of the school facilities construction is composed of three steps. The operations corresponding to level 1 and level 2 are as follows. (1) 2 preparatory work categories; preparation period and temporary construction. (2) 17 architectural work categories; temporary construction, foundation & pile work, reinforced concrete work, steel roof work, brick work, plaster work, tile work, stone work, waterproof construction, wood work, interior construction, floor work, metal work, roof work, windows construction, glazing work and paint construction. (3) 7 mechanic and fire work categories; outside trunk line work, plumbing work, air-conditioning equipment work, machine room work, city gas plumbing work, sanitation facilities and inspection & test working. (4) 4 civil work categories; wastewater work, drainage work, pavement work and other work. (5) 1 landscaping work categories; planting work. The work breakdown structure was derived from interviews with experts based on the milestones and detailed statements of existing school facilities. The analysis of precedence relations by school facilities work activity utilized PDM(Precedence Diagramming Method)which does not need a dummy and the relations were applied using FS(Finish to Start), FF(Finish to Finish), SS(Start to Start), SF(Start to Finish). The analysis of this study shows that if one work activity is delayed, the entire construction duration may be delayed because the majority of the works are FS relations. Therefore, it is necessary to use the Lag at the appropriate time to estimate the standard construction duration of the school facility construction. Lag is a term used only in the PDM method and it is used to define the relationship between the predecessor and the successor in creating the network milestone. And it means the delay time applied to the two work activities. The results of this study can reasonably estimate the standard construction duration of school facilities and it will contribute to the quality of the school facilities construction.

• International Journal of High-Rise Buildings
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• v.9 no.3
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• pp.301-306
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• 2020

In tall building construction, the appropriate control of lifting loads on tower cranes is critical in terms of the construction duration of structural works. The adoption of efficient construction methods can be the most effective way of minimizing the inputs of tower cranes and making a lifting plan and management easier. Based on actual data from a tall building project, this study comparatively analyzes lifting loads of tower cranes by the core structure preceding construction method (CSPCM) and the core structure succeeding construction method (CSSCM). The results revealed that the CSSCM could reduce up to about 56.3% of lifting loads for core works and significantly enhance lifting efficiency compared with the CSPCM. Consequently, this enabled a substantial reduction in the construction duration of structural works. This study provides a practical reference to assist engineers and managers in applying efficient construction methods and lifting equipment operation in tall building projects.

• Korean Journal of Construction Engineering and Management
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• v.1 no.3 s.3
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• pp.75-80
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• 2000

In scheduling multi-unit projects, several alternatives can exist in network construction due to repetitiveness of their activities. Project duration is affected not only by the duration of each activity but also by the arrangement of repeating activities in such projects. This paper provides a network compression method that assigns predecessors to each activity to minimize its float time. Different to the previous efforts that utilized line of balance as the base scheduling-model, this research adopts precedence diagram arranged in two coordinates, the space axis and the resource one. This method seeks the most appropriate predecessors for each activity in each direction of the two coordinates for the purpose of minimizing the idle resource and space. This activity arrangement method was applied to a multi-unit apartment-construction project, to prove its capability of network compression. The result shows that the method successfully sought room for saving construction duration by changing the activity arrangement. The network compression method presented in this research can be utilized in multi-unit construction projects such as apartment complex projects.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.60-61
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• 2016

The specialty of Construction Manager's work is largely depends on the project progress stage and the type of management work. However, at present, career management system manages only the type and duration of the construction project, disregarding specialty and competence. However, in order to select a right construction manager for the client's needs or project characteristics, career management should be subdivided and managed according to the project progress stages or the types of management. In addition, this career management plan is essential for construction managers to receive appropriate wages for their careers and competences. Therefore, this study proposes a classification system for the integration of career, work, and competency to promote effective career management.