• Korean Journal of Construction Engineering and Management
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• v.22 no.2
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• pp.42-52
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• 2021

The cost of remodeling parking lots of apartment houses accounts for about 20 percent of the total cost of remodeling. This means that when the remodeling cost of the underground parking lot is known, it becomes possible to estimate the total construction cost. The standard of estimation referenced when calculating the construction cost is difficult to apply to calculating the remodeling cost. Thus, a construction cost estimation model that reflects the characteristics of remodeling construction is necessary. This study developed a basic construction cost estimation model for expansion remodeling of underground parking lots of apartment houses that calculates the approximate cost of construction by reflecting the characteristics and design elements of remodeling. Based on literature review and consultation with experts, 37 activities of underground parking lot remodeling construction were derived. In order to enable calculation of approximate construction cost before the remodeling design drawing is finalized, the quantity calculation formula and unit price for each activity were presented. Based on expert advice, 13 factors that affect the increase in construction cost and weights of each factor were determined. As a result of applying three cases of remodeling complexes to the basic cost estimation model, the accuracy was confirmed to be 93 percent on average.

• Korean Journal of Construction Engineering and Management
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• v.22 no.3
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• pp.69-78
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• 2021

Estimated construction cost is an important index to secure an optimal budget which needs to go into construction projects in the previous of basic design phase. In order for public institutions to calculate the estimated construction cost, the cost per unit area of public buildings is used. However, the current calculation method of the estimated construction cost in public buildings is impossible to reflect the characteristics of many facilities and combinations. The purpose of this study is to develop an estimation model in the previous of basic design phase for the elementary, middle and high school facilities. it is expected that it is possible to estimate the construction cost of the elementary, middle and high schools in a reasonable and reliable manner through the estimation model developed in this study.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1223-1230
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• 2009

In the construction industry, Case-Based Reasoning (CBR) is considered to be the most suitable approach and determining the attribute weights is an important CBR problem. In this paper, a method is proposed for determining attribute weights that are calculated with attribute relation. The basic items of consideration were qualitative and quantitative influence factors. These quantitative factors were related to the qualitative factors to develop a Cost Drivers-structural equation model which can be used to estimate construction cost by considering attribute weight. The process of determining the attribute weight-structural equation model consists o 4 phases: selecting the predominant Cost Drivers for the SEM, applying the Cost Driers in the SEM, determining and verifying the attribute weights and deriving the Cost Estimation Equation. This study develops a cost estimating technique that complements the CBR method with a Cost Drivers-structural equation model which can be actively used during the schematic estimating phases of construction.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.226-227
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• 2019

The basic type construction cost which is the base of the building cost estimation is being adjusted according to the price changes by utilizing the apartment construction cost index in order to flexibly operate it. In this study, we analyzed the change trends and characteristics of the housing cost index for the basic type building cost model project operated from September, 2012 to March, 2018. As a result, the increase in material costs is slight while the share of the labor cost increased in the construction cost due to the rise of labor unit price, leading to a perceived increase in sensitivity of labor costs. We should be careful to keep the sensitivity of the material cost and the labor cost to an appropriate level so that the index may not be distorted.

• Korean Journal of Construction Engineering and Management
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• v.7 no.5
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• pp.167-176
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• 2006

It was found that Korean Standard of Estimate which has been used as the only basis of cost estimate of public construction projects had some side effects such as jerry-build construction and over-estimation because it failed to reflect the current price and the state-of-the-art construction methods in a changing construction environment. Therefore, the government decided to gradually introduce historical construction cost into cost estimate of public construction projects from 2004. This paper presents analytic criteria and a process model for deducing more current and reasonable historical construction cost for contract items from not only previous contract prices but also all of the other bid prices that were not contracted. The procedure of estimating actual unit cost proposed in this paper focuses on the removal of abnormal values including strategically too low or high prices and the time correction. In addition, basic research is conducted for the correction of actual unit cost through the analysis of fluctuation of bid price depending on bidding types and rates of successful bid. It is anticipated that the effective use of the proposed process model for estimating actual unit cost would make the cost estimation more current and reasonable.

• Korean Journal of Construction Engineering and Management
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• v.7 no.4 s.32
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• pp.91-99
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• 2006

The purpose of this study is propose an Artificial Neural Network(ANN) model for the construction estimate of the public educational facility at conceptual stage. The current method for the preliminary cost estimate of the public educational facility uses a single-parameter which is based on basic criteria such as a gross floor area. However, its accuracy is low due to the nature of the method. When the difference between the conceptual estimate and detailed estimate is huge, the project has to be modified to meet the established budget. Thus, the ANN model is developed by using multi-parameters in order to estimate the project budget cost more accurately. The result of the research shows 6.82% of the testing error rates when the developed model was tested. The error rates and the error range of the developed model are smaller than those of the general preliminary estimating model at conceptual stage. Since the proposed ANN model was trained using the detailed estimate information of the past 5 years' school construction data, it is expected to forecast the school project cost accurately.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.166-167
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• 2016

Unlike the past, supported by the development of digital technologies, free-form buildings are frequently designed with creative thoughts of architectural designers. However, there are some difficulties preventing successfully completion of projects, like reduced productivity and increased construction duration and cost upon the process of producing and installing concrete panels for free-form structures. In particular, there are active studies on the CNC machine for production of free-form concrete panels. Yet, it is difficult to effectively and easily come up with information on production and installation of free-form, curve-surfaced panels which are difficult to be mathematically defined. This requires a lot of manpower and time to implement the curved surfaces of free-form buildings as intended by architects. Accordingly, it needs a model that can effectively create production-installation data of free-form concrete panels for successful free-form building projects. Thus, the purpose of the study is to suggest data estimation model of production-installation using mathematical algorithm in free-form concrete panels. The study results will realize effective production and installation of free-form concrete members, allowing improved productivity of projects, reduced cost and shortened construction duration.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.103-111
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• 2023

Accurate cost estimation in the early stages of a construction project is critical to the successful execution of the project. In this study, an ANFIS model was presented to predict construction costs in the early stages of a construction project. To increase the usability of the model, open construction cost data was used, and a model using limited information in the early stage of the project was presented. We analyzed existing studies related to ANFIS to identify recent trends, and after reviewing the basic structure of ANFIS, presented an ANFIS model for predicting conceptual construction costs. The variation in prediction performance depending on the type and number of membership functions of the ANFIS model was analyzed, the model with the best performance was presented, and the prediction accuracy of representative machine learning models was compared and analyzed. Through comparing the ANFIS model with other machine learning models, it was found to show equal or better performance, and it is concluded that it can be applied to predicting construction costs in the early stage of a project.

• Korean Journal of Construction Engineering and Management
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• v.9 no.3
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• pp.65-74
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• 2008

Public institutions recognize the importance of cost management from the planning stage but they do not have an organized construction cost estimation and management system. Thus, at the stage of planning a new public construction project and estimating the cost, those in charge of budgeting estimate construction cost based on existing data and experiences, compare construction cost estimated after the basic design stage and the execution design stage with budgets, and then decide whether to continue the project or change the design according to the budgets. Therefore, we would develop the cost prediction model through regression analysis that can predict construction cost in Schematic Design Phase of the Public Multi-Family housing. Accordingly, if public institutions have a construction cost prediction model and management system that can estimate the optimum construction cost, they can make and execute budgets in a more efficient way than they do at present.

• Journal of the Korea Institute of Building Construction
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• v.3 no.2
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• pp.95-102
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• 2003

Financial difficulties and claims frequently stop construction works and cause subsequent contract cancellations. However, as the criteria to assess costs have not been established, many cases of legal disputes over the assessment of cancellation costs are taking place and the concerned parties are suffering the loss of time and money. Therefore, the present research aimed at developing a rational and systematic model of cancellation cost assessment following the cancellation of contracts. The research was carried out in the following methods and scopes. 1 ) The research was focused on the assessment of fair cancellation costs from constructors' side for contracts cancelled by any causes for which the owners have liability. 2) To obtain basic materials about cancellation cost assessment methods, contracts, claims, contract cancellations and construction-related laws at home and abroad were examined. 3) A cost assessment model was developed for systematization and efficient operation of cancellation cost assessment, and the reliability and efficiency of the proposed model was verified through a case study. The conclusions drawn from the research are as follows. The importance of the cancellation cost assessment model was confirmed as, using the cancellation cost assessment model, direct cancellation cost and indirect cancellation cost could be assessed systematically, the number of disputable items could be reduced because reasonable evidences of actual spending were presented, and the loss of constructors could be minimized because systematic and rational cost assessment became possible for many disputable cases of indirect cancellation cost, which the constructors had been unable to prove so far though having spent.