• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.195-200
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• 2021

In recent years, Vietnam's economic growth rate has been attributed to the growth of many well-managed industries within Southeast Asia. Among them is the civil construction industry. Construction projects typically take a long time to complete and require a huge budget. Many socio-economic variables and factors affect total construction project costs due to market fluctuations. In recent years, crucial socioeconomic development indicators of construction reached a fairly high growth rate. Also, most infrastructure and construction projects have a high degree of complexity and uncertainty. This makes it challenging to predict the accurate project price. These challenges raise the need to recognize significant factors that influence the construction price index of civil buildings in Vietnam, both micro and macro. Therefore, this paper presents critical factors that affect the construction price index using the fuzzy extent analysis process in an uncertain environment. This proposed quantitative model is expected to reflect the uncertainty in the process of evaluating and ranking the influencing factors of the construction price index in Vietnam. The research results would also allow project stakeholders to be more informed of the factors affecting the construction price index in the context of Vietnam's civil construction industry. They also enable construction contractors to estimate project costs and bid rates better, enhancing their project and risk management performance.

• Journal of Construction Engineering and Project Management
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• 제3권2호
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• pp.21-34
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• 2013

Various risk factors affect construction projects. Due to the uncertainties created by risk factors, actual activity durations frequently deviate from the estimated durations in either favorable or adverse direction. For this reason, evaluation of schedule uncertainty is required to make decisions accurately when managing construction projects. In this regard, this paper presents a new computer simulation model - the Repetitive Schedule Risk Analysis Model (RSRAM) - to evaluate unit-based repetitive building project schedules under uncertainty when activity durations and risk factors are correlated. The proposed model utilizes Monte Carlo Simulation and a Critical Path Method based repetitive scheduling procedure. This new procedure concurrently provides the utilization of resources without interruption and the maintenance of network logic through successive units. Furthermore, it enables assigning variable production rates to the activities from one unit to another and any kind of relationship type with or without lag time. Details of the model are described and an example application is presented. The findings show that the model produces realistic results regarding the extent of uncertainty inherent in the schedule.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.502-506
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• 2013

The cash flow forecasting is normally done by contractors in construction industry at early stages of the project for contractual decisions. The decision making in such situations involve uncertainty about future cash flows and assessment of working capital requirements gains more importance in projects constrained by cash. The traditional approach to assess the working capital requirements is deterministic in and neglects the uncertainty. This paper presents an alternate approach to assessment of working capital requirements for contractor based on fuzzy set theory by considering the uncertainty and ambiguity involved at payment periods. Statistical methods are used to deal with the uncertainty for working capital curves. Membership functions of the fuzzy sets are developed based on these statistical measures. Advantage of fuzzy peak working capital requirements is demonstrated using peak working capital requirements curves. Fuzzy peak working capital requirements curves are compared with deterministic curves and the results are analyzed. Fuzzy weighted average methodology is proposed for the assessment of peak working capital requirements.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.902-907
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• 2005

This study was undertaken to develop a comprehensive scheduling method which applied the core concept(DBR) of TOC to PERT, and to combine Monte Carlo Simulation to revise the uncertainties of activities then to eliminate project duration uncertainty. Most of the project duration overlooks the fact that in spite of minimizing the project duration, the uncertainty of constrained resources still puts the reliability of project duration in jeopardy. For the contractor, however, the most important thing is to comply the project scheduling with the planning to reduce the uncertainty of the project activities, operational interaction and project duration. In order to demonstrate that the model can be used in construction project, the scheduling of a steel-structure project was used as a case study to verify the validity of this model.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.238-244
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• 2022

Civil projects are associated with many uncertainties because they involve a long duration, many resources, a large area, and many supply chains. Therefore, the price of a civil project is not simply proportional to the quantity and unit price of the item but has a variable value, including uncertainty risk. This study investigates the influence of the uncertainty factors in the pre-bid clarification document on bid price formation during the project bidding phase. To this end, civil projects from the California Department of Transportation (Caltrans) were used as research data. This study randomly selected fifty sample data from each of twelve counties from 2008-to 2020: six hundred. The authors observed that each project sample had 0 to n query cases due to uncertainty. Then, this study examined the project uncertainty cases and categorized them into the following four uncertainty factors: 'conflict' (UF1), 'impossibility' (UF2), 'lack' (UF3), and 'missing' (UF4). Under the extracting process, the cases are classified into four uncertainty factors. With the project not containing any uncertainty factors as a control group, the project containing these uncertainty factors was designated as an experimental group. After comparing the bidder's price, the experimental group's bid price was higher than the control group's. This result suggests that uncertainty factors in bid documents induce bidders to set a high bid price as a defense against uncertainty.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.67-73
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• 2022

Construction bid documents contain various errors or discrepancies giving rise to uncertainties. The errors/discrepancies/ambiguities in the bid document, if not identified and clarified before the bid, may cause dispute and conflict between the contracting parties. Given the fact that bid document is a major resource in estimating construction costs, inaccurate information in bid document can result in over/under estimating. Thus, any questions from bidders related to the errors in the bid document should be clarified by employers before bid submission. This study aims to examine the pre-bid queries, i.e., pre-bid request for information (RFI), from state DoTs of the United States to investigate error types most frequently encountered in bid documents. For the study, around 200 pre-bids RFI were collected from state DoTs and were classified into several error types (e.g., coordination error, errors in drawings). The analysis of the data showed that errors in bill of quantities is the most frequent error in the bid documents followed by errors in drawing. The study findings addressed uncertainty types in construction bid documents that should be checked during a bid process, and, in a broader sense, it will contribute to advancing the construction management body of knowledge by clarifying and classifying bid risk factors at an early stage of construction projects.

• Architectural research
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• 제10권1호
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• pp.41-48
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• 2008

Construction projects have frequently exceeded their schedule despite reliable estimates at the start of a project. This problem was attributed to unpredictable causes at the beginning and to shortage of proper tools to accurately predict project completion date. To supplement this difficulty, project managers need a comprehensive system that can be employed to monitor the progress of an ongoing project and to evaluate potential delay for achieving the goal on time. This paper proposed a progressive-based expert system for quantitative assessments of project delay at the early stages of the execution. Furthermore, the system is used to inspect the change of the uncertainty on completion date and its magnitude. The proposed expert system is helpful for furnishing project managers a warning signal as a project is going behind schedule and for tracking the changed uncertainty at a desired confidence level. The main objectives of this paper are to offer a new system to overcome the difficulties of conventional forecasting tools and to apply a construction project into the system to illustrate its effectiveness. This paper focuses on construction phase of project development and is intended for the use by project managers.

• 한국건설관리학회논문집
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• 제8권5호
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• pp.191-200
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• 2007

This paper introduces a tool for predicting potential cost overrun during project execution and for quantifying the uncertainty on the expected project cost, which is occasionally changed by the unknown effects resulted from project's complications and unforeseen environments. The model proposed in this stuff is useful in diagnosing cost performance as a project progresses and in monitoring the changes of the uncertainty as indicators for a warning signal. This model is intended for the use by project managers who forecast the change of the uncertainty and its magnitude. The paper presents a mathematical approach for modifying the costs of incomplete work packages and project cost, and quantifying reduced uncertainties at a consistent confidence level as actual cost information of an ongoing project is obtained. Furthermore, this approach addresses the effects of actual informed data of completed work packages on the re-estimates of incomplete work packages and describes the impacts on the variation of the uncertainty for the expected project cost incorporating Multivariate Probabilistic Analysis (MPA) and Bayes' Theorem. For the illustration purpose, the Introduced model has employed an example construction project. The results are analyzed to demonstrate the use of the model and illustrate its capabilities.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1081-1087
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• 2009

An automatic construction system in Korea is now at the stage of the full automation like in Japan, and an actual pilot project is going to be built in 2009. However, in developing a new construction system that has never been implemented before, there is a need to assess the performance and to consider the uncertainty of the system. The program evaluation and review technique (PERT) allows dealing with this uncertainty. Thus, this paper implements an analysis of the process of steel fabrication and makes suggestions for time-related problems arising from the analysis. The time required for steel erection by the automatic system was compared with that in the traditional method. In the result, finding out another construction process and improving robot performance were proposed to resolve the problems. The results will contribute to promoting the development of an efficient system for the new automatic construction system.

• 국제강구조저널
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• 제18권5호
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• pp.1508-1524
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• 2018

Hysteretic energy dissipating devices (HEDDs) have been increasingly applied to building construction to improve the seismic performance. The seismic responses of such damped structures are significantly affected by HEDD's structural properties. An accurate investigation on the propagation of HEDD's structural properties is required for reasonable evaluation of the seismic performance of a structure. This study aims to develop simplified methods that can estimate the collective uncertainty-propagation to the seismic response of damped structures employing HEDDs. To achieve this, three- and six-story steel moment-resisting frames were selected and the propagations of the individual HEDD's property-uncertainties were evaluated when they are subjected to various levels of seismic demand. Based on the result of individual uncertainty-propagations, a simplified method is proposed to evaluate the variation of seismic response collectively propagated by HEDD's property-uncertainties and is verified by comparing with the exact collective uncertainty-propagation calculated using the Monte Carlo simulation method. The proposed method, called as a modified SRSS method in this study, is established from a conventional square root of the sum of the squares (SRSS) method with the relative contributions of the individual HEDD's property-uncertainty propagations. This study shows that the modified SRSS method provides a better estimation than the conventional SRSS method and can significantly reduce computational time with reasonable accuracy compared with the Monte Carlo simulation method.