Hybrid forecasting system based on case-based reasoning and analytic hierarchy process for cost estimation

Cost estimating of highway projects with high accuracy at the early stage of project development is crucial for planning and feasibility studies. Various research have been attempted to develop cost prediction models in the early stage of a construction life cycle. This study uses the hybrid estimating tool to provide an effective cost data management for highway projects and accordingly develops a realistic cost estimating system. This study focused on the development of a more accurate estimate technique for highway projects in South Korea at the early stage using hybrid analytic hierarchy process (AHP) and case-based reasoning (CBR). Real case studies are used to demonstrate and validate the benefits of the proposed approach. It is expected that the developed CBR system is to provide decision-makers with accurate cost information to asses and compare multiple alternatives for obtaining the optimal solution and controlling cost

Long-term variations of water quality and phosphorus loading in Lake Andong, Korea

Tropic state parameters were measured in a reservoir (Lake Andong, Korea) from 1993 to 2000. Phosphorus loading from the watershed was estimated by measuring total phosphorus concentration in the main inflowing stream (the Nakdong River). Phosphrus discharge of the pen-type fish farms was estimated from the amount of fish feed supplied annually and the rate of phosphrus excretion per feed weight. Minimum transparency in summer was only about 2.0m in 1993 and 1994, but it decreased to about 1.2m in 1997 and 1998, and recovered to about 2.3m in 1999 and 2000. TP increased from 11～30 mgP/m³ in 1993 to 18～42 mgP/m³ in 1998, but recovered to 8～13mgP/m³ in 2000, whereas TN decreased slightly from1.81～2.96mgN/L in 1993 to 1.17～1.80mgN/L in 2000. TN/TP ratio decreased from 82～281 in 1993 to 21～143 in 1998, but again increased to 101～209 in 2000 due to the decrease of TP. The average chlorophyll a concentration in growing season was in the range of 4.8-16.2mg/m³ from 1993 to 1997, but it decreased to 3.7-5.2 mg/m³ after 1998. The major cause of the trophic state recovery is thought to be the removal of fish farms in April 1998.Article信州大学山地水環境教育研究センター研究報告 2: 131-134(2004)departmental bulletin pape

Critical Success Factors for Implementing Integrated Construction Project Delivery

Purpose: The purpose of this paper is to identify the critical success factors (CSFs) to implement integrated project delivery (IPD) systems in the Korean construction industry. Design/methodology/approach: This study categorized potential CSFs and analyzed them using factor analysis and multiple regression analysis to choose the best ones based on responses from Korean construction experts. Findings: In total, 29 potential factors were selected and categorized into 7 CSFs using factor analysis. Originality/value: The outcomes of the study are useful as a reference for applying the IPD system in different developing countries and mid-sized construction industries

Optimizing the Mixing Proportion with Neural Networks Based on Genetic Algorithms for Recycled Aggregate Concrete

This research aims to optimize the mixing proportion of recycled aggregate concrete (RAC) using neural networks (NNs) based on genetic algorithms (GAs) for increasing the use of recycled aggregate (RA). NN and GA were used to predict the compressive strength of the concrete at 28 days. And sensitivity analysis of the NN based on GA was used to find the mixing ratio of RAC. The mixing criteria for RAC were determined and the replacement ratio of RAs was identified. This research reveal that the proposed method, which is NN based on GA, is proper for optimizing appropriate mixing proportion of RAC. Also, this method would help the construction engineers to utilize the recycled aggregate and reduce the concrete waste in construction process

The limnological survey of a coastal lagoon in Korea: Lake Hwajinpo

Physicochemical parameters, plankton biomass, and sediment were surveyed from 1998 to 2000 on two months interval in a eutrophic costal lagoon (Lake Hwajinpo, Korea) segregated from the sea by a sand dune. Littoral zone is well developed and floating-leaved aquatic plants also thrive, A shallow sill divides the lake into two basins. It has permeation of seawater and chemoclines formed by salinity were observed at 1m demth all the year around. DO was often very low(＜1mgO₂/L) at hypolimnion. Temperature inversions were observed in November. Transparency was 0.2～1.7m. Nitrate and ammonium concentrations were very low (＜0.1mgN/L), even though TN was usually 2.0～3.5mgN/L. TN/TP was generally lower than the Redfield ratio. TSI was 63～74, COD, TP, and TN of sediment were 3.1～40.3mgO₂/g, 0.9～1.39mg/m³. Two basins showed different phytoplankton communities with Oscillatoria sp., Trachelomonas sp., Schiaochlarnys gekatinosa, and Anabaena spiroides dominant in South basin, and with Trachelomonas sp., Schroederia sp., Schizochlamys felatinosa, and Trachelomonas sp. dominant in the North basin. The seasonal succession of phytoplankton was very fast, possibly due to sudden changes in physical characteristics such as wind, turbidity, salinity and light, etc.Article信州大学山地水環境教育研究センター研究報告 2: 127-130(2004)departmental bulletin pape

Comparison of Two Ultrasmall Superparamagnetic Iron Oxides on Cytotoxicity and MR Imaging of Tumors

Purpose: This study was performed to compare the cytotoxicity and magnetic resonance (MR) contrast in diverse cultured cells and xenograft tumors models of two ultra-small superparamagnetic iron oxides (USPIOs), thermally cross-linked superparamagnetic iron oxide nanoparticles (TCL-SPION) and monocrystalline iron oxide nanoparticles (MION-47)

Balanced approach for tendering practice at the pre-contract stage: the UK practitioner's perspective

Tender documents often lack clarity and are incomplete, making it difficult for contractors to appropriately price projects. A general view is that the quality of tender documents has declined, which has affected the bidding strategies of contractors. However, the academic literature has focused mainly upon the views of contractors. To obtain a more balanced view of tendering practices, in-depth interviews were conducted with 10 practitioners (client, consultant, and contractor) who are involved in a common project at the same time in the UK construction industry. The contractor was satisfied that the quality of tender documents had been consistent. By contrast, both the client and the consultant agreed that the quality of tender documents is an ongoing issue. During the study it was revealed that tendering practice is influenced by the relationship between stakeholders or the unbalanced access to information rather than the accuracy and analysis of tender documentations. Tendering practices and proposed efficient ways of improving the bidding environment were examined. Using the awareness of other project stakeholder’s perspectives, this study can help the contractor to establish suitable tendering practices, and to mitigate tender risk at the bidding stage, which could effectively be implemented in the UK construction industry

Contractor-led design risk management in international large project: Korean contractor’s perspective

To mitigate the contractor’s design related risks from the bid stage, this study identifies the design risk management (DRM) factors and analyzes them in terms of their importance weight and application preference. With the awareness of detailed DRM factors and their interrelationship structure, the contractor can understand how the design-related risk issues are interconnected with various production activities on site and prepare suitable management methods according to the project’s situation from an early project stage

Decision Making Method Based on Importance-Dangerousness Analysis for the Potential Risk Behavior of Construction Laborers

Unsafe behavior contributes to 90% of the causes of construction accidents. To prevent construction accidents, studies on existing unsafe behaviors have been regularly conducted. However, existing studies generally tend to average the survey results and conduct analyses thereon, and such a method cannot consider the potential risk as regards people’s anxiety about a certain unsafe behavior. Thus, this research suggests an Importance-Dangerousness Analysis (IDA) technique so that potential risks due to unsafe behaviors of laborers working in the construction sector could be evaluated. In order to verify the applicability of the suggested technique, an actual survey was conducted, and the results of Importance-Performance Analysis (IPA) and IDA were compared with each other. It was found that, unlike IPA, unsafe behaviors that could pose potential risks were confirmed by IDA. Further, unsafe behaviors in the construction sector that should be urgently addressed were also studied. Finally, the IDA suggested in this research could contribute to effective construction safety management on-site by supporting the decisions of the safety manager based on the unsafe behavior analysis of construction laborers