Kyo-Jin Koo

A CBR-based hybrid model for predicting a construction duration and cost based on project characteristics in multi-family housing projects

Decision-making in the early stage of a project has a significant impact on the project. However, limited and uncertain information on the project and a complex correlation among various factors that affect the project’s construction duration and cost, make it difficult to predict and manage the project. Therefore, this study developed a case-based reasoning (CBR)-based hybrid model with which to predict the construction duration and cost of a project in its early stage. One hundred and one cases among multi-family housing projects that were completed between 2000 and 2005 were used. The CBR-based hybrid model developed in this study is the result of integrating the advantages of (i) prediction methodologies, such as case-based reasoning, multiple regression analysis, and artificial neural networks, (ii) the optimization process using a genetic algorithm, and (iii) the probability distribution and the analysis process of outlier using Monte-Carlo simulation. The results of this study are expected to suppo...

GA-Based Fuel-Efficient Transfer Path Selection Model for Delivering Construction Materials

AbstractOil prices may continue to rise indefinitely until alternative fossil fuels or renewable energies are commercialized. In this sense, general contractors who have the responsibility of delivering construction materials should select an optimized alternative that needs the least oil among the various combinations of truck types of logistic companies, routes, and suppliers. In this context, the objective of this paper was to develop a genetic-algorithm (GA)-based fuel-efficient transfer path selection model (GAFETPSM) for delivering construction materials with minimum fuel consumption. A GAFETPSM considers the truck type, road type, and fuel-efficiency variation by load, and the constraints of capacity, number of trucks, and total load to be delivered. Finally, a case study showed that GAFETPSM is superior to the simulated-annealing (SA)-based model in terms of fuel consumption in delivering the same weight of construction materials. It is expected that GAFETPSM could contribute to reduce the carbon-...

Comparison between Labor Inputs by Quantity per Unit Method and by Actual Data Method in the Apartment Housing Construction Work - Focusing on Masonry·Plaster·Waterproofing·Tile Labors -

Abstract : The standard production unit system is the most basic element in our country construction. However, this standard production unit system shows a large difference in the actual amount of labor input for works at the Apartment housing construction, Therefore, it may be a reasonable alternative to estimate the cost of construction by historical cost data, works will be calculated the cost of labor must determine the exact amount and It is necessary to determine the exact amount of labor input for the construction progress management. This study examines the results of comparing the standard production unit system and the actual amount of labor counting in apartment housing construction was completed in the metropolitan area since 2000, the following results were obtained. the actual amount of labor input are looked for 1.184person/1000 of masonary, 0.084persons/㎡ of plaster, 0.039 persons/㎡ of Waterproofing, 0.059 persons/㎡ of tile at the Apartment housing construction. in the actual amount of labor counting Compared with standard production unit system, masonry ratio of 59.8%, plaster ratio of 41.3%, waterproofing ratio of 31.5%, tile ratio of 34.3% and The labor rate in the works was the lowest in the plaster. was relatively high in the masonary. Therefore, the amount of labor country apartment housing construction is preferably calculated on historical cost data. But it seems that the amount of labor necessary complement ongoing close enough to the actual standard production unit system a major variable in construction management.

A Forecasting Model for Rental Prices of Tower Cranes

In the Koran construction industry, the conventional methods to estimate tower crane rental prices are based on either standard unit prices or historical prices in previous contracts. These methods, however, have had problems not properly reflecting the level of tower crane rental demand. The present paper claims that rental prices are determined by the market prices affected by supply and demand mechanism rather than the two methods mentioned above. In this perspective, this study proposes a regression model by that construction contractors can assess appropriate rental prices of tower cranes considering both the factor of rental demands and adjusting factors. It specifically investigates the contracted prices of T-type 12-ton tower cranes which are the most common type of tower cranes in the field of apartment construction.

Trend Analysis of Labor Input Ratios by Work Types in Apartment Housing Constructions

Apartment Housing 25 in the field of construction since 2000 collected by types of labor: reinforced concrete, plaster, internal, equipment, electrics·communication, the other work. And the performance of labor input was collected in the amount of construction work performed on a monthly basis. After changing the construction period in the standardization work that is 100% of the construction period, the amount was converted into labor ratio by type. Analysis of the input flow rate and the amount of labor conclusions were as follows: 1 The size of the labor rate is reinforced concrete work (38.25%), plastering work (5.10%), internal work (5.67%), equipment work (9.10%), electrics·communication (8.76%), the other works (33.12%) and the size of labor rate is the largest work in reinforced concrete work. 2 The peak of labor input ratio was from 52.5% month to 62.5% month. This was when the labor rate of 3.6%. 3 The period month of the largest labor ratio% is 35% month by reinforced concrete construction, and this time it was 2.12% per month labor rate, and reinforced concrete construction is finishing from 65% month to 80% month. This showed the greatest congestion of mutual interference between each works is being continue. The results of this study are the greatest congestion in apartment housing construction has informed the high period(%months), which is essential to a successful project.

Development of Safety Management Index for Contractor Assessment in Bidding Process

The construction industry is still the most risky industry and labor accident is a significant management factor on construction site. Safety management has been studied for improving the safety performance on construction sites. However, Almost all of them have been considered on the site safety management for the contractors and evaluation of accident rate. To resolve the limitation of current research, this study is focused on considering accident result and effort by performing the evaluation of safety level of the head office and site in construction companies. By studying the research about a safety management and interviewing with specialists in safety management, 7 items were selected and weighted based on the KOSHA18001 List. Consequently, The checklist was developed to evaluate safety performance management in construction company and Safety Management Index was suggested to coordinate 1) the score of results in accident rate and 2) the effort to evaluate a safety performance management. Safety Management Index is more helpful to evaluate the safety management results and effort. As a result of considering the score of the accident rate and the safety performance management, the outcome of prequalification was changed. Using this index, contractors will attempt to prevent accidents and owners will be able to discriminate individual differences in bidding process.

Agent-Based Approach for Intelligent Automated Landfill Operation System

Workers and operators in sanitary landfill sites face the health risk due to the constant exposure to the toxic solid, liquid, and gaseous by-products of the waste materials. One solution to this problem is automation technology that can increase productivity and quality as well as safety. But, developing an automated system for landfill operations is usually a complex task due to the dynamic aspect of the environment and the uncertainty in task planning. Cooperation is another fundamental concern that is fundamental for a collection of automated equipment to achieve more than the sum of what each can achieve individually. To reduce the above complexity to some extent, a new approach is required for developing an automated landfill system. This paper describes an agent-based cooperative system for an automated landfill system that is to perform landfill compaction operations effectively, and to provide a means of cooperation between landfill equipment. Three kinds of landfill agents are defined and a methodology for simple task allocation among them is suggested. The critical factors for task allocation are identified, and then, based on these factors, a cost model for calculating the execution cost of each piece of equipment is established. For effective cooperation, all agents in the proposed system should have autonomy and interact with each other in a partially centralized and partially decentralized way.