• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.4
• /
• pp.1693-1705
• /
• 2013

To restore old aqueduct in Korea which is a irrigation bridge to supply water in paddy field area, it is needed to estimate approximate costs of restoration because the basic design for estimation of construction costs is often ruled out in current system. In this paper, estimating models of construction costs were developed on the basis of performance data for restoration of RC aqueduct bridges since 2003. The regression analysis (RA) model and case-based reasoning (CBR) model for the estimation of construction costs were developed respectively. Error rate of simple RA model was lower than that of multiple RA model. CBR model using genetic algorithm (GA) has been applied in the estimation of construction costs. In the model three factors like attribute weight, attribute deviation and rank of case similarity were optimized. Especially, error rate of estimated construction costs decreased since limit ranges of the attribute weights were applied. The results showed that error rates between RA model and CBR models were inconsiderable statistically. It is expected that the proposed estimating method of approximate costs of aqueduct restoration will be utilized to support quick decision making in phased rehabilitation project.

• Korean Journal of Construction Engineering and Management
• /
• v.7 no.5
• /
• pp.159-166
• /
• 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.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.1183-1188
• /
• 2009

Estimating project costs during the early stage of conceptual planning is very important when deciding whether to approve the project and allocate an appropriate budget. However, due to greater uncertainties involved in a project, it is challenging to estimate costs during this initial stage within a reasonable tolerance. This paper attempts to develop a cost-estimate model for public road projects under these circumstances and limitations. In the conceptual planning stage of a road project, there is only limited information for cost estimation, for example, such input data as total length of the route, origin and destination, number of lanes, general geographic characteristics of the route, and other basic attributes. This implies that the model should individuate suitable but restricted information without considering detailed features such as quantity of earthwork and a detailed route of a given condition. With these limited facts, this paper applies a case-based reasoning (CBR) method to solve a new problem by deriving similar past problems, which in turn is used to estimate the cost of a given project based on best-fitted previous cases. To develop a CBR cost-estimate model, the authors classified 8 representative variables, including project type, the number of lanes, total length, road design grades, etc. Then, we developed the CBR model, primarily by using 180 actual cases of public road projects, procured over the last decade. With the CBR model, it was found that the degree of error in estimation can be reasonably reduced, to below approximately 30% compared to the final costs estimated upon the completion of detailed design.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.250-251
• /
• 2021

A subcontract work order is the basis of the construction process and consists of the root and trunk of the construction industry. The construction process through a subcontract work order is an important element of project success, and it is the basic unit of creating profit in the construction industry. Therefore, correct analysis and forecasting of subcontract work orders allow correct estimation of construction cost and profit which is the foundation of corporate decision making. This study has started to provide predictions of subcontractor's bidding-ratio for decision-making. Since the actual project data has been used in this study, the contribution level of the model is highly expected in actual field. The statistical confidential level of adjusted decision coefficient is concluded low because of limited sample numbers. However, its accuracy and confidence level can be increased through increasing sample numbers, considering more variables, and studying of reducing error.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2007.11a
• /
• pp.872-875
• /
• 2007

Estimation of total construction period and cost in the early stage of the project is very important. Simulation is one of the method considering proper compound such as tools, materials for effective construction management and estimating and analysing affected factors to construction through making suitable process. This study is to develop the model by using Arena simulation considering limited facts like blast time in a subway tunnel construction of both sides inner city. Developed model is easily useful type by using Visual Basic program, and can obtain total construction period and cost as a result. It could be used as a decision making tool in early stage of the construction.

• Korean Journal of Construction Engineering and Management
• /
• v.21 no.3
• /
• pp.39-47
• /
• 2020

There are two kinds of cost estimate system in construction in china. Quota valuation model is a traditional cost estimate system under the unity of quantity and price, which is easier and has been used for decades. But the Quota valuation model becomes increasingly unsuited to the needs of society with the development of market economy. To meet the needs of China's market economy development and construction works in the field of international cooperation, the Bill of Quantities valuation model was introduced in 2003. However, there are still many shortcomings and deficiencies in the course of implementation of Bill of Quantities valuation model. In addition, interest in the Chinese construction market continues to increase in Korea due to the recent new North Korean policy and China's the Belt and Road policy. This paper aims to examine the cost estimate system of public construction works in China, and to provide basic data for deriving future improvement plans by comparing and analyzing it with standard cost estimate system in Korea.

• Journal of the Society of Naval Architects of Korea
• /
• v.52 no.1
• /
• pp.1-7
• /
• 2015

The weight estimation of floating offshore structures such as FPSO, TLP, semi-Submersibles, Floating Offshore Wind Turbines etc. in the preliminary design, is one of direct measures of both construction cost and basic performance. Through both literature investigation and internet search, the weight data of floating offshore structures such as FPSO and TLP was collected. In this study, the weight estimation model with the genetic programming was suggested for FPSO. The weight estimation model using genetic programming was established by fixing the independent variables based on this data. In addition, the correlation analysis was performed to make up for the weak points of genetic programming; it is apt to induce over-fitting when the number of data is relatively smaller than that of independent variables. That is, by reducing the number of variables through the analysis of the correlation between the independent variables, the increasing effect in the number of weight data can be expected. The reliability of the developed weight estimation model was within 2% of error rate.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.6
• /
• pp.530-538
• /
• 2014

The weight estimation of floating offshore structures such as FPSO, TLP, semi-Submersibles, Floating Offshore Wind Turbines etc. in the preliminary design, is one of important measures of both construction cost and basic performance. Through both literature investigation and internet search, the weight data of floating offshore structures such as FPSO and TLP was collected. In this study, the weight estimation model was suggested for FPSO. The weight estimation model using non-linear regression analysis was established by fixing independent variables based on this data and the multiple regression analysis was introduced into the weight estimation model. Its reliability was within 4% of error rate.

• Korean Institute of Interior Design Journal
• /
• no.16
• /
• pp.75-81
• /
• 1998

With the rise of the economic level and the improvement of the standard of living the size of the interior work is becoming large and specialized, With the recent opening of the domestic interior decoration market the order of the large-scale interior decoration work is actively received and its efficient construction is vigorously made. Accordingly reliability is required in keeping with all the accuracy of computing interior construction expenses systematically is importantly emerging. The estimation sheet written in a kind of process mode and in an area made as the construction expense breakdown mode were statistically treated and analyzed as well as quantity computation breakdown data. In determing the major factors that expert an influence on the factors of changes in construction expenses as well as the compositional ratio of construction work that becomes basic material for developing the cost model of interior decoration work the following conclusion could be made: Improvement should be made to suit the present situation by synthesizing and arranging the data practically used in current interior construction expenses. Required construction expenses for the kind of work common to each construction field are showing a given proportion and the required construction expenses of rather small scale interior construction work tend to be irregular. It is necessary to compute optimal construction expenses by calculating the optimal period of work and working personnel in consideration of the influential factor in each work.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.928-934
• /
• 2009

Although the evolution and deployment of information technologies will undoubtedly play an important role in the current construction industry, many engineers are still unsure of the economic value of using these technologies. Especially for the planning of a construction project, a collaboration system to utilize the whole resources is a essential tool for the successful outcome. A detailed, authoritative, and readily accessible information model is needed to enable engineers to make cost-effective decisions among established and innovative plan alternatives. Most engineers rely on limited private experiences when they create solutions or design alternatives. Initial planning is crucial for the success of the construction project. Most construction projects are done through collaboration of engineers who have different specialized knowledge. Information technologies can dramatically enhance the performance of the collaboration. For the information delivery, we need a mediator between engineers. Object-based 3-D models are useful for the communication and decision assistance for the intelligent project design. In this paper, basic guidelines for the 3-D design according to different construction processes are suggested. Adequate interoperability of 3-D objects from any CAD system is essential for the collaboration. Basic architectures of geometry models and their information layer were established to enable interoperability for design checks, estimation and simulation. A typical international project for roadway was chosen for the pilot project. 3-D GIS model was created and bridge information models were created considering several requirements for planning and decision making of the project. From the pilot test, the integrated construction project planning using 3-D information models was discussed and several guidelines were suggested.