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Park M.,Seoul National University | Kim W.-Y.,Construction and economics Research Institute of Korea | Lee H.-S.,Seoul National University | Han S.,University of New South Wales
Automation in Construction | Year: 2011

Supplying ready mixed concrete (RMC) in both a timely and cost-effective manner has been a particular challenge for RMC suppliers. To address this issue, a dynamic simulation model is developed using system dynamics. This model represents the generic RMC operation process and can customize its structure and parameters for different operational conditions. Through model simulation, the RMC supply process is analyzed, focusing on the tradeoff between the truck mixer dispatching interval and queuing time on-site. The research findings indicate that the model-generated information helps in achieving an economical RMC supply by maintaining the number of queuing truck mixers at the desired level, while satisfying the contractor's need. Ultimately, this dynamic model could potentially be used as an effective automated tool to assist RMC suppliers in supply planning. © 2010 Elsevier B.V. All rights reserved. Source


Kang S.,Construction and economics Research Institute of Korea | Kang S.,Hanyang University | Kang S.,University of California at Berkeley | Seo J.,Hanyang University
Journal of Construction Engineering and Management | Year: 2013

This study presents a geographic information system (GIS)-based method for determining the optimal layout of a haul route for large earthmoving projects. The methodology focuses on the use of cost distance measurements to implement a least-cost path analysis to calculate the route with the shortest weighted distance between cut and fill areas. Various factors such as truck speed, construction costs, and land use that affect haul road layout are investigated. Linear interpolations based on linguistic evaluations of experienced field experts are utilized to quantify the factors. An earthmoving project from a large-scale dam construction was used as a case study to verify the applicability of the proposed method, and the route produced with the new method was compared to real road design data. The results showed the potential of the method as a practical approach to determining the optimal haul route for earthmoving. © 2013 American Society of Civil Engineers. Source


Jung S.,Hanyang University | Jang K.,Korea Advanced Institute of Science and Technology | Yoon Y.,Korea Advanced Institute of Science and Technology | Kang S.,Construction and economics Research Institute of Korea
Journal of Safety Research | Year: 2014

Introduction: This study combined vehicle to vehicle crash frequency and severity estimations to examine factor impacts on Wisconsin highway safety in rainy weather. Method: Because of data deficiency, the real-time water film depth, the car-following distance, and the vertical curve grade were estimated with available data sources and a GIS analysis to capture rainy weather conditions at the crash location and time. Using a negative binomial regression for crash frequency estimation, the average annual daily traffic per lane, the interaction between the posted speed limit change and the existence of an off-ramp, and the interaction between the travel lane number change and the pavement surface material change were found to increase the likelihood of vehicle to vehicle crashes under rainfall. Results: However, more average daily rainfall per month and a wider left shoulder were identified as factors that decrease the likelihood of vehicle to vehicle crashes. In the crash severity estimation using the multinomial logit model that outperformed the ordered logit model, the travel lane number, the interaction between the travel lane number and the slow grade, the deep water film, and the rear-end collision type were more likely to increase the likelihood of injury crashes under rainfall compared with crashes involving only property damage. Practical implications: As an exploratory data analysis, this study provides insight into potential strategies for rainy weather highway safety improvement, specifically, the following weather-sensitive strategies: road design and ITS implementation for drivers' safety awareness under rainfall. © 2014 Elsevier Ltd. Source


Park M.,Seoul National University | Ingawale-Verma Y.,National University of Singapore | Kim W.,Construction and economics Research Institute of Korea | Ham Y.,Seoul National University
KSCE Journal of Civil Engineering | Year: 2011

For construction policies to be effective and efficient, an integrated and systematic approach, with which the effectiveness of alternative policies can be examined in advance by anticipating the private sector's response and subsequent changes in the industry environment is needed. As an effort to address this issue, a model-based approach is presented for construction policymaking and an example of a prefabrication policy in Singapore is given. In this study, the policy models developed using system dynamics simulate the performance of the Singapore construction industry and examine the effectiveness of alternative prefabrication policies in a qualitative and quantitative manner. Having obtained policy implications from the model structures and simulation results, policy initiatives are suggested along with discussions on the associated potential risks. Based on the research findings, we could conclude that a model-based approach is helpful in developing an effective construction policies by providing policymakers in a government or corporate with an integrated view on the policy application process and a tool to examine alternative policies in a systematic manner. © 2011 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg. Source


Han S.H.,Yonsei University | Kim D.Y.,Yonsei University | Jang H.S.,Construction and economics Research Institute of Korea | Choi S.,Yonsei University
Habitat International | Year: 2010

Over the last decade, the international construction industry has changed drastically in many ways, including: the terms of competition rules and delivery systems for the selection of contractors, financial resource diversity, leading contractors in the revenue rankings, the key products and new emerging markets. This paper investigates the important changes for global contractors through various documentation analyses as well as in-depth interviews with 80 industry experts. This paper then analyzes the common strategies and lessons obtained from the cases of leading global contractors that have sustained their growth in the competitive global construction during the last decade. It was found that those firms were quite proactive and responsive to changing markets by increasing their overseas revenues and enhancing their competency through more diversified products in order to stabilize their revenue structure. In addition, they significantly increased their upstream/downstream functional capabilities; hence becoming more competent service providers, able to grow in these rapidly changing market conditions. © 2009 Elsevier Ltd. All rights reserved. Source

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