• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.175-180
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• 2006

Total conceptual cost estimates and the assessment of the reliability of these estimates are critical in the early stages of a building construction project. The purpose of this study is to propose the method to clients or estimators for improving the reliability of conceptual cost estimates by evaluating the reliability of conceptual cost estimates. The data from 83 building construction projects were collected for this study. The results showed that the proposed method can propose alternatives to clients or estimators for improving the reliability of conceptual cost estimates with the process of evaluation, review and feedback. This process can assist clients in their evaluation of the reliability of the estimated cost and the probability of exceeding the target cost, and in their re-estimation after dealing with the elements that influence the conceptual cost estimate badly.

• Journal of the Korea Institute of Building Construction
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• v.10 no.2
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• pp.133-138
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• 2010

Conceptual cost is estimated with insufficient information at an early stage of a building construction project, resulting in an inevitable gap between conceptual estimated cost and real constructed cost. For a project to be successful, this gap must be managed to be lower than a reliable level. Therefore, the purpose of this study is to propose a structural process for managing the reliability of conceptual cost estimates at an early stage of a building construction project. In researching this study, conceptual cost estimate experts were interviewed,and a risk management process was studied. Reliability assessment and a review process for improving the quality of conceptual cost estimate and the planning strategy of reliability management based on previous similar projects were added to the present estimate process. The proposed reliability management process will improve the chances of a successful project, by helping to decrease the risk of conceptual estimated cost.

• Korean Journal of Construction Engineering and Management
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• v.8 no.4
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• pp.155-166
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• 2007

The purpose of this research is to develop a conceptual model and prototype that establishes a new approach for building cost estimating in the schematic design phage. This research use the method that analyzes quantity and unit price separately to enhance schematic cost estimating through conducting literature review andi analyzing existing schematic cost estimating methods. In addition, this study proposes tile concept of cost breakdown structure including two more classifications: building element and floor compared to existing one only classified by trade. Thus, a Quantity Based Active Schematic cost Estimating(Q-BASE) model is developed founded on those two concepts. By applying proposed schematic cost estimating model, historical structure cost of residential complex building project is analyzed, and then, based on this analysis, prototype is implemented.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.120-125
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• 2003

The estimated construction costs derived at the Planning stage of a project are utilized as important data determining the feasibility of overall project. Therefore the clients usually expect to have estimations of the construction cost as precise as possible and there has been extensive studies carried out by the cost specialists worldwide to satisfy this client's specific need whereas the local estimators still heavily rely on producing quantities and detail quotations only. This paper is to introduce a case study where elemental/functional area cost analysis is incorporated into a database system for the improved accuracy in cost estimations.

• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.141-150
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• 2019

In the overseas plant construction market, the domain construction firms' construction capability has been greatly improved, but the capability of project management is evaluated to be insufficient compared to the technical aspect. Project management capabilities from the initial planning stage of project execution are regarded as the core competence of advanced construction companies. Among them, it is urgent to improve the capacity of conceptual estimate for domestic companies. In this study, the researchers surveyed and analyzed the methodology of estimating project cost in the planning phase of the plant project and developed an estimation method by conducting a case study analysis. Based on the logic of the cost index and parametric estimation method among the existing estimation methodology, the estimation tool was developed by deriving the input and output variables tailored to the plant project. The validity of the proposed methodology was evaluated by comparing the accuracy between the project estimate amount of the case project and the actual project amount. In order to increase the utilization of the developed conceptual estimate methodology,for plant construction project, it is necessary to systematize the data of the historical project data. Increasing the accuracy of future project cost estimates is directly related to increasing project award and profitability of the domestic construction company.

• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.147-153
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• 2020

It is important to estimate the optimal construction cost at the early stage of the project. In this regard, conceptual cost estimate is an important factor for estimate optimal construction cost. However, domestic conceptual cost estimate are only used as cost per unit area according to the building type, and it's accuracy is not high. Hence, the purpose of this study is to calculate the approximate quantity and cost for reinforcing bars, concrete, and formwork by presenting a regression formula based on the total floor area of the common work items in the frame work. In order to verify the accuracy and validity of the regression formula presented in this study, a comparative analysis was performed by applying the regression formula and the traditional approximate quantity take-off method to real cases. As a result, the estimated error rate of the traditional method was -102~+55%, and exceeded the estimated conceptual cost estimate accuracy range of -50~+100% suggested by AACE(American Association of Cost Engineering). On the other hand, the error rate of the regression formula method presented in this study was -6.4~+11.62%. This can be used not only for conceptual cost estimate range of accuracy, but also for detailed estimates. However, it is necessary to analyze the factors that affect the unit price as well as quantity in order to calculate the appropriate cost.

• Korean Journal of Construction Engineering and Management
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• v.9 no.6
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• pp.175-184
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• 2008

For deciding the profitability and feasibility of the construction project, the schematic estimation has to not only link the design decision-making but also estimate the cost with reliability. The prototype-based schematic estimation system was developed for easily linking with design-making and supports to evaluate the design alternatives in the design development stage but didn't consider the cost estimated by parameter and additional work items by users. This research presents the object-parameter based schematic estimation model in the design development stage that can lead to accurately estimate the cost by using historical data from the high-storied office buildings. For the development of the proposed model for schematic estimation, after analyzing and classifying the work items from the Bills of Quantities(BOQs) and drawings of historical data, this research proposed the methods of estimating cost in accordance with attributes of each work item. In addition, a case study is performed for the effectiveness as comparing the previous estimating method with the proposed model.

• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.183-190
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• 2020

Currently, the multi-unit houses are the largest in the ratio of housing types, and the number of households in multi-unit houses is steadily increasing. As the multi-family housing project continues, the accuracy of estimates for decision-making and feasibility assessment are required in the early stages of the project. Therefore, this study selected the influential factors affecting the estimated estimate and showed the relative importance of each factor through weight analysis and suggested the method of calculating the estimated estimate to improve the accuracy. The calculation plan presented through this study will be used as a useful data for project feasibility review and is expected to make a great contribution in preventing the economic loss of the client.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4176-4184
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• 2015

Cost Estimate for alternative in design phase of construction become criterion for profitability and feasibility analysis of projects. Initial design phase performed schematic estimate based on similar data in the past. The quantity take-off according to estimators experience and calculation method are occurred different or missing. IT (Information Technology) technology evolution has been promoting BIM technology in construction. It is changing the paradigm of planning, design, construction and maintenance phase throughout the construction project. A number of studies have been attempted to apply BIM technology in the construction. In this paper, we propose schematic estimation framework linking standard format IFC (Industry Foundation Classes) and estimate related knowledge. As a result, it performs a cost prediction for decision-making in the design phase, and expected to overcome the limitations of previous studies. In addition, it is possible actively coping with changes.

• Korean Journal of Construction Engineering and Management
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• v.21 no.6
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• pp.113-124
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• 2020

Social movements to improve the performance of buildings through remodeling of aging apartment houses are being captured. To this end, the remodeling construction cost analysis, structural analysis, and political institutional review have been conducted to suggest ways to activate the remodeling. However, although the method of analyzing construction cost for remodeling apartment houses is currently being proposed for research purposes, there are limitations in practical application possibilities. Specifically, In order to be used practically, it is applicable to cases that have already been completed or in progress, but cases that will occur in the future are also used for construction cost analysis, so the sustainability of the analysis method is lacking. For the purpose of this, we would like to suggest an automated estimating method. For the sustainability of construction cost estimates, Deep-Learning was introduced in the estimating procedure. Specifically, a method for automatically finding the relationship between design elements, work types, and cost increase factors that can occur in apartment remodeling was presented. In addition, Monte Carlo Simulation was included in the estimation procedure to compensate for the lack of uncertainty, which is the inherent limitation of the Deep Learning-based estimation. In order to present higher accuracy as cases are accumulated, a method of calculating higher accuracy by comparing the estimate result with the existing accumulated data was also suggested. In order to validate the sustainability of the automated estimates proposed in this study, 13 cases of learning procedures and an additional 2 cases of cumulative procedures were performed. As a result, a new construction cost estimating procedure was automatically presented that reflects the characteristics of the two additional projects. In this study, the method of estimate estimate was used using 15 cases, If the cases are accumulated and reflected, the effect of this study is expected to increase.