Hyoungkwan Kim

Structuring the prediction model of project performance for international construction projects: A comparative analysis

Early understanding of project conditions is crucial so as to proactively respond to the variable situations of a project. Particularly, international construction projects are affected by more complex and dynamic factors than domestic projects; frequently being exposed to serious external uncertainties such as political, economical, social, and cultural risks, as well as internal risks from within the project itself. This study develops a structural equation model (SEM) to predict the project success of uncertain international construction projects. Through a comparative analysis of SEM with a multiple regression analysis and artificial neural network, SEM shows a more accurate prediction of performance because of its intrinsic ability to consider various risk variables in a systematic and realistic way. In addition, the use of SEM allows for visually depicting the paths of how those complicated variables are interrelated so as to promote the clear understanding of the complex system and its underpinned causes that critically affect the project success.

Computer vision techniques for construction safety and health monitoring

For construction safety and health, continuous monitoring of unsafe conditions and action is essential in order to eliminate potential hazards in a timely manner. As a robust and automated means of field observation, computer vision techniques have been applied for the extraction of safety related information from site images and videos, and regarded as effective solutions complementary to current time-consuming and unreliable manual observational practices. Although some research efforts have been directed toward computer vision-based safety and health monitoring, its application in real practice remains premature due to a number of technical issues and research challenges in terms of reliability, accuracy, and applicability. This paper thus reviews previous attempts in construction applications from both technical and practical perspectives in order to understand the current status of computer vision techniques, which in turn suggests the direction of future research in the field of computer vision-based safety and health monitoring. Specifically, this paper categorizes previous studies into three groups-object detection, object tracking, and action recognition-based on types of information required to evaluate unsafe conditions and acts. The results demonstrate that major research challenges include comprehensive scene understanding, varying tracking accuracy by camera position, and action recognition of multiple equipment and workers. In addition, we identified several practical issues including a lack of task-specific and quantifiable metrics to evaluate the extracted information in safety context, technical obstacles due to dynamic conditions at construction sites and privacy issues. These challenges indicate a need for further research in these areas. Accordingly, this paper provides researchers insights into advancing knowledge and techniques for computer vision-based safety and health monitoring, and offers fresh opportunities and considerations to practitioners in understanding and adopting the techniques.

Analyzing Schedule Delay of Mega Project: Lessons Learned From Korea Train Express

In 2004, Korea became the fifth country in the world to own and operate a high-speed railway called Korea Train eXpress (KTX). Numerous uncertainties and challenges during planning and managing phase resulted in schedule delays and cost overruns. The delay causes of each activity along the 412 km Korea high-speed railway route were very difficult to identify because KTX project consisted of 11 141 different activities. This paper evaluates challenges, obstacles, and performances of KTX project. First, critical sections in the railway route that influenced significant delays to project completion were identified. Then, delay causes of these critical sections were investigated thoroughly. The analysis discovered five major delay causes for KTX project. They are lack of owners abilities and strategies to manage hi-tech oriented mega project; frequent changes of routes triggered by conflicts between public agencies and growing public resistance from environmental concerns; the inappropriate project delivery system; a lack of proper scheduling tool tailored for a linear mega project; and redesign and change orders of main structures and tunnels for high-speed railway, which is fundamentally different from the traditional railway construction. Based on the in-depth analysis of KTX project, through which a conceptual framework was established to identify the various facets of mega projects, this paper suggests lessons learned for engineers to better prepare and respond to potential causes of schedule delays for mega projects.

Greenhouse Gas Emissions from Onsite Equipment Usage in Road Construction

AbstractGreenhouse gas (GHG) emissions from onsite equipment usage have not been fully investigated despite their high reduction potential. This study presents a comparative analysis of the generation of GHGs by various equipment types used in different construction activities. Twenty-four cases involving a typical road construction project in Korea were selected for comparison. GHG emissions from onsite equipment usage for different activities were estimated using final design documents, which fully defined the construction project. This study also provides the expected ranges of such emissions according to equipment productivity related to site conditions of good, fair, and poor. For the major activities that produced most of the GHG emissions from onsite equipment, the value was estimated to be in the range of 256.52–376.70  tCO2e, with 282.17 tCO2e for fair site conditions. A focus group interview (FGI) was conducted to identify guidelines that can be applied to improve equipment productivity to reduc...

Ubiquitous Sensor Network for Construction Material Monitoring

Timely acquisition of construction resource information is an essential task for construction engineers and managers. Due to the harsh and dynamic construction environment, it is not easy to acquire construction information in real time. This paper presents a radio frequency identification (RFID) and ZigBee (IEEE 802.15.4)-based system to manage materials on a busy construction site where a data communications system is not in place. RFID tags are attached to and used to identify various kinds of construction materials, and the ZigBee communication technology is used to wirelessly transfer this information. To confirm the viability of our system, the RFID and ZigBee technologies were assessed using an indoor experiment. Following this, a field experiment was then conducted. On a building construction site, a range of construction materials was identified using RFID tags and this information was transferred to an end user with the help of ZigBee multihop networking. The results of the field experiment showed an acceptable reading range and rate for the proposed system. Therefore, the integrated system with RFID and ZigBee modules demonstrated great potential for improving the existing management processes for construction resources on large and complex construction sites.

Determining the Value of Governmental Subsidies for the Installation of Clean Energy Systems Using Real Options

Limiting greenhouse gas emissions has continually gained importance since the Kyoto protocol became effective in 2005. A variety of efforts have been made to reduce energy consumption and introduce supposedly clean and renewable energy that can replace fossil fuelbased energy sources. However, many clean energy sources are not economically viable by themselves, and, therefore, government subsidies are necessary to provide sufficient economic motivation for the installation of new types of energy. For that reason, it is necessary to develop a method for reasonably and accurately determining an appropriate level of government subsidy for private entities. In this paper we propose a real option-based framework for rationally quantifying the amount of government subsidy required by private entities in order to implement a clean energy generation system. A case study that involved the installation of a photovoltaic system in an average household in Seoul, Korea was conducted in order to verify the proposed fra...

Capital structure optimization for build–operate–transfer (BOT) projects using a stochastic and multi-objective approach

Private financing has long been recognized as playing an important role in providing public infrastructure facilities worldwide. Private investors–operators, however, are often exposed to the financial risk of low profitability due to the inaccurate forecast of facility demand, operating income, and maintenance costs. From the operator’s perspective, a sound and thorough financial feasibility study is required to establish the appropriate capital structure of a project. To this end, operators are likely to reduce the equity amount to minimize the level of risk exposures, whereas creditors or lenders continue to raise it in an attempt to secure a decent level of financial responsibility from the operators. This paper presents an optimized capital structure model for both creditors and operators to reach an agreement for a balanced structure that synchronizes both profitability and repayment capacity. The model is developed with the use of Monte Carlo simulation and a multi-objective generic algorithm (GA) ...

Framework for Estimating Greenhouse Gas Emissions Due to Asphalt Pavement Construction

AbstractGreenhouse gas (GRG) emissions are an important primary criteria for environmental evaluation. As a project evaluation criterion, this study developed a framework that could estimate GHG emissions in asphalt pavement construction based on the limited information available in the feasibility study phase. A thorough literature review and in-depth interviews with domain experts in the field of road engineering were conducted to identify the input variables for this framework. By considering the characteristics of the input variables, such as material type, geometric shape of the structure, and earthwork quantities, an artificial neural network and a parametric calculation were used to develop the framework for estimating GHG emissions. When applied to real-life asphalt pavement projects in the Republic of Korea, the framework produced an average estimation error of 11.2%, which was considered sufficiently accurate for the planning phase. The proposed framework is expected to help decision makers easi...

Applicability of 4D CAD in Civil Engineering Construction: Case Study of a Cable-Stayed Bridge Project

Four-dimensional (4D) computer-aided design (CAD) has been credited with improving construction planning procedures. The integration of three-dimensional CAD with schedule information has enabled the effective detection of design and planning flaws in many construction projects. However, the benefit of 4D CAD has been centered on architectural constructions, as other areas such as civil infrastructure have seldom been the target of 4D CAD application. This paper presents a case study in which a cable-stayed bridge construction was analyzed and modeled using the 4D graphic simulation approach. The cable-stayed bridge was chosen for the case study because it suitably represents the complex nature of modern civil infrastructure. 4D CAD models were developed at three different levels of detail: activity, discrete operation, and continuous operation. The clear definitions of the three levels of detail of 4D CAD and their application results for the cable-stayed bridge are presented herein.

Mobile computing platform for construction site management

Ever improving smart phones and mobile computing technologies provide engineers unprecedented opportunities to innovate the existing processes of construction projects. Researchers in the construction industry tried to use mobile computing technologies for enhancing the management process of construction project on site. This study aims to present a location-based construction site management system using a mobile computing platform. The system was developed using iPhone SDK (Software Development Kit) from Apple Inc. Task information provided in the system was easily associated with the corresponding location information. This unique feature enabled the construction engineers to easily understand where the tasks and problems were. The communication capability of mobile devices through construction drawing presentation also offered effective information exchange among construction participants. The mobile system operated on smart phone is expected to assist construction engineers in achieving real-time access to customized, location-based construction information.