• Korean Journal of Construction Engineering and Management
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• v.17 no.3
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• pp.71-80
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• 2016

PERT(Project Evaluation and Review Technique) is typical method in order to probabilistically establish the schedule plan for large scale complex project or mega project. PERT technique is impossible to estimate relationship of each activity probabilistically when there are overlapping relationships because it is limited to Finish-to-Start(FS) relationship. In order to overcome this kind of limitation of PERT technique, PLET(Probabilistic Linkage Evaluation Technique) has been suggested to probabilistically estimate project duration for various overlapping relationships for each activity. However, estimating project duration by PLET technique only considers uncertainty of relationship between activities and not activity time, thus it is not the perfect duration estimating method. The main objective of this research is to propose the integration model of PERT and PLET and verify its probabilistic validity. By verifying application of time calculation method of integration model in practical case, this research will suggest probabilistic project duration estimating method in schedule plan of high-risk construction industry.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.121-122
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• 2015

The demand on free-form buildings is gradually increasing, but there are several problems such as increased cost and construction duration, and decreased constructability at the construction phase upon construction of a building owing to the difficulty of member production-installation. To solve these problems, a technology to produce FCP using a CNC machine was developed. Basically, it delivers the information on a free-form building designed to the CNC machine, the shapes of RTM and PCM are created using the information delivered and FCP are produced with the RTM and PCM which act as forms. Since the construction duration and project cost are limited on site, the efficiency of FCP production-installation is significant for application of the technology. For it is almost impossible to change the production-installation layout and process once they are set in the construction phase, they should be carefully determined. Before the production-installation layout are established, it is necessary to analyze the factors that influence the duration. Thus, the study intends to analyze influence factors in PCM mold on estimation of the production-installation duration for FCP. According to the analysis of influence factors, a simulation model for estimation of the duration that changes depending on the constraint conditions can be built.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.642-648
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• 2009

Determining the total duration for a construction project is an integral part of project management in the construction industry. This is to ensure the project and all its associated activities can be carried out and completed within the time frame stipulated. There are several commonly used scheduling methods and techniques in project management, some of which involves manual calculation while others involve computer software. This paper looks into the various time determination methods, extracting out their differences and similarities. It also seeks to draw out the problems when determining time for projects, especially those encountered of case studies. Based on the results from the case studies, there were delays on certain projects even though time determination had been carried out rigorously prior to the commencement of the projects. This paper seeks to develop a time determination model, which incorporates risk management techniques into the calculations in order to improve the method for time estimation to minimize the chances of project delay.

• Korean Journal of Construction Engineering and Management
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• v.18 no.2
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• pp.12-20
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• 2017

The biggest reason to prefer the remodeling is a relatively short period of time (5~6 years) compared to the reconstruction work that takes 8~9 years. In addition, from the perspective that the period of temporary residence is usually 24 months, the necessity of shortening is greater. Also, since the remodeling construction period is approximately 28~35 months on average, the strategies and efforts are needed to make up for the shortening the remodeling construction period. For these reasons, this paper is to develop an estimating model for normal project duration of apartment remodeling project. This model is reflected in the remodeling properties thorugh difference analysis of the new apartment construction project. Demolition works, reinforcement works, extension works are different, so this paper newly defines these construction work's duration in normal project duraion of remodeling. Case study and experts interviews are used to validate normal project duration. This model can be used to calculate rough construction period each alternatives, and will help a strategic decision making among the stakeholders.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.155-158
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• 2009

During the construction project period, a lot of change orders happen in the design and construction stage Especially, The change order during construction stage causes the huge construction cost increase and duration delay. Accordingly, research on the change order of the construction stage is being progressed relatively active in the design stage, but the design changes are rarely made. In the design stage, the owner has to pay a design addition cost when change order due to the demands of owner happens. However Korea has not the specific standard about design additional cost in design stage. Therefore, this study analyzes problems of design additional cost estimation methods through the case study, and then indicates the method that the ratio distributes to details dividing design tasks and the method of the PM(Project Management). Eventually, this study expects to minimize claim related the design additional cost in design stage.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.791-795
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• 2005

A simulation model is proposed to evaluate the effect of correlations between activity durations on the overall project duration. The proposed model incorporates NORTA, a recent developed statistical method, into the simulation process to allow arbitrarily specified marginal distributions for activity durations and any desired correlation structure. The generality is of practical value when systematic data is not available and planners have to rely on arbitrary experts' estimation, which may involve a mixed situation when some activity durations are continuously distributed whereas others are discrete outcomes. The proposed model is validated by showing that the correlation coefficients of the simulation results are close to the originally specified ones. The simulation results are compared to two conventional approaches: PERT and simulation without correlation. The comparisons illustrate that the proposed model can provide important management information, which would otherwise be distorted due to the neglect of the correlations between activity durations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.200-207
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• 2017

3D printing is making a huge difference to existing industries and is beginning to be applied in the field of construction. 3D printing construction differs from existing construction techniques. Therefore, new construction processes need to be developed. In particular, the accurate construction duration is linked directly to a successful project. A method for estimating the construction duration for 3D printing construction is necessary. In this study, a 3D printing construction process and duration estimation method were derived to prepare for the future introduction of 3D printing in construction. The scope of the study was assumed to be 3D printing equipment capable of pouring concrete, and limited to a frame structure construction. The developed construction period estimation method was applied to the virtual test model. As a result of applying the test model, the construction duration was shortened by approximately 50% compared to the existing construction technique. The method of estimating the construction period developed in this study can be applied to 3D printing constructions in the future and help establish a business plan.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.9-16
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• 2016

The project schedule risk in the engineering and facility construction industry is increasingly considered as important management factor because the risks in terms of schedule or deadline may significantly affect the project cost. Especially, the project-based operating companies attempt to find the best estimate of the project completion time for use at their proposals, and therefore, usually have much interest in accurate estimation of the duration of the projects. In general, the management of projects schedule risk is achieved by modeling project schedule with PERT/CPM techniques, and then performing risk assessment with simulation such as Monte-Carlo simulation method. However, since these approaches require the accumulated executional data, which are not usually available in project-based operating company, and, further, they cannot reflect various schedule constraints, which usually are met during the project execution, the project managers have difficulty in preparing for the project risks in advance of their occurrence in the project execution. As these constraints may affect time and cost which role as the crucial evaluation factors to the quality of the project result, they must be identified and described in advance of their occurrence in the project management. This paper proposes a Bayesian Net based methodology for estimating project schedule risk by identifying and enforcing the project risks and its response plan which may occur in storage tank engineering and construction project environment. First, we translated the schedule network with the project risks and its response plan into Bayesian Net. Second, we analyzed the integrated Bayesian Net and suggested an estimate of project schedule risk with simulation approach. Finally, we applied our approach to a storage tank construction project to validate its feasibility.

• Land and Housing Review
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• v.12 no.4
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• pp.93-101
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• 2021

As the number of small households (1 to 2 persons per household) in Korea gradually increases, so does the importance of housing supply policies for small households. In response to the increase in small households, the government has been continuously supplying urban housing for these households. Since housing for small households is a sales and rental business similar to apartments and general business facilities, it is important for the building owner to calculate the project's estimated construction duration during the planning stage. Review of literature found a model for estimating the duration of construction of large-scale buildings but not for small-scale buildings such as urban housing for small households. Therefore this study aimed to develop and verify a model for estimating construction duration for urban housing at the planning stage based on multiple regression analysis. Independent variables inputted into the estimation model were building site area, building gross floor area, number of below ground floors, number of above ground floors, number of buildings, and location. The modified coefficient of determination (R_a²) of the model was 0.547. The developed model resulted in a Root Mean Square Error (RMSE) of 171.26 days and a Mean Absolute Percentage Error (MAPE) of 26.53%. The developed estimation model is expected to provide reliable construction duration calculations for small-scale urban residential buildings during the planning stage of a project.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.191-192
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• 2011

The construction projects contain a lot of variables and risk affecting productivity. The duration of the project must be recognized important as for quality, unit cost and safety. There is need for improving work efficiency by investigating relationship of works to prevent delay. This study focuses on analysing the delay factors of steel staircase system to suggest regression model that enables construction productivity estimation. The position of the observers and construction delay factors were expressed by the independent variable of the regression model and productivity was expressed by a dependent variable. This paper suggests quantitative productivity and it is expected that will be helpful estimating application in construction new technologies.