Gomez-Cunya, Luis-Angel; Fardhosseini, Mohammad Sadra; Lee, Hyun Woo; Choi, Kunhee. (2020). Analyzing Investments in Flood Protection Structures: A Real Options Approach. International Journal Of Disaster Risk Reduction, 43.
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Abstract
The soaring number of natural hazards in recent years due largely to climate change has resulted in an even higher level of investment in flood protection structures. However, such investments tend to be made in the aftermath of disasters. Very little is known about the proactive planning of flood protection investments that account for uncertainties associated with flooding events. Understanding the uncertainties such as when to invest on these structures to achieve the most optimal cost-saving amount is outmost important. This study fills this large knowledge gap by developing an investment decision-making assessment framework that determines an optimal timing of flood protection investment options. It combines real options with a net present value analysis to examine managerial flexibility in various investment timing options. Historical data that contain information about river water discharges were leveraged as a random variable in the modeling framework because it may help investors better understand the probability of extreme events, and particularly, flooding uncertainties. A lattice model was then used to investigate potential alternatives of investment timing and to evaluate the benefits of delaying investments in each case. The efficacy of the proposed framework was demonstrated by an illustrative example of flood protection investment. The framework will be used to help better inform decision makers.
Keywords
Decision-making; Flood Protection; Real Options Theory; Investment Decision-making
Ho, Chung; Lee, Hyun Woo; Gambatese, John A. (2020). Application of Prevention Through Design (PTD) to Improve the Safety of Solar Installations on Small Buildings. Safety Science, 125.
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Abstract
As a viable, clean and renewable energy resource, solar energy has gained a significant interest in the US residential sector. Most solar systems are installed on rooftops to take advantage of available space and reduce land use. However, this installation environment also exposes workers to unique safety hazards related to existing roof conditions such as slippery roofing materials, irregular roof layouts, and steep roof slopes. Although Prevention through Design (ND) has been widely considered as an effective way to address safety issues during the design phase, little to no studies have applied ND to improve safety in solar energy installations. To fill this knowledge gap, this research aimed to investigate how, during the design phase, to address the safety concerns of solar workers when installing solar energy systems on residential buildings. Through a series of interviews, four case studies, and a seminar, seven solar ND attributes were identified: roofing materials, roof slopes, roof accessories, panel layouts, fall protection systems, lifting methods and electrical systems. Based on the attributes, a ND protocol was developed that can serve as guidance for implementing ND in solar installations. This paper presents the research activities and findings, and feedback gained from solar contractors through a seminar on the study. The study is expected to contribute to reducing safety hazards by implementing ND, help improve safety performance in solar installations on small residential buildings and support the promotion of safety in sustainable construction.
Keywords
Roofing Materials; Renewable Energy Sources; Sustainable Construction; Solar Energy; Clean Energy; Construction Safety; Prevention Through Design; Small Buildings; Solar Installations; Buildings (structures); Construction Industry; Hazards; Occupational Safety; Roofs; Safety; Solar Power; Sustainable Development; Steep Roof Slopes; Design Phase; Solar Energy Installations; Solar Workers; Installing Solar Energy Systems; Residential Buildings; Seven Solar Ptd Attributes; Roof Accessories; Ptd Protocol; Solar Contractors; Safety Performance; Viable Energy Resource; Clean Energy Resource; Renewable Energy Resource; Us Residential Sector; Solar Systems; Installation Environment; Unique Safety Hazards; Roof Conditions; Slippery Roofing Materials; Irregular Roof Layouts; Issues; Accident Prevention; Protocol; Energy Sources; Residential Areas; Land Use; Prevention; Design; Falls; Occupational Hazards; Contractors; Residential Energy; Protection Systems; Renewable Energy; Buildings; Roofing; Layouts
Hyun Woo Lee; Anderson, S.M.; Yong-Woo Kim; Ballard, G.. (2014). Advancing Impact of Education, Training, and Professional Experience on Integrated Project Delivery. Practice Periodical On Structural Design And Construction, 19(1), 8 – 14.
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Abstract
With the increased interest in applying integrated forms of project delivery to complex and uncertain construction projects, the building industry has been experiencing an increased demand for integrated project delivery (IPD). With the trend, many empirical studies have examined the collaborative characteristics of IPD and reported that participants must make the necessary transition for its contractual, technological, and cultural requirements. However, little study has been done to investigate relevant education, training, or professional experience that can support the transition. In response, this study used an online survey that was designed to investigate the level and type of education, training, and professional experience of project members and their corresponding level of background knowledge for each IPD requirement. The key survey findings include (1) project members have the highest level of background knowledge on the cultural requirements of IPD, but the lowest level on the technological requirements; (2) the group with more design-build experience has more background knowledge; (3) the group that received an IPD kick-off training has more background knowledge; and (4) having a lean construction class can prepare students for the IPD environment. It is expected that the survey findings will advance the education, training, and levels of background knowledge of IPD participants, which will enhance their IPD experience accordingly.
Keywords
Buildings (structures); Construction Industry; Contracts; Cultural Aspects; Industrial Training; Professional Aspects; Project Management; Construction Project; Building Industry; Integrated Project Delivery; Ipd; Contractual Requirement; Cultural Requirement; Professional Experience; Design-build Experience; Training Impact; Education Impact
Lee, Yong-Cheol; Shariatfar, Moeid; Rashidi, Abbas; Lee, Hyun Woo. (2020). Evidence-Driven Sound Detection for Prenotification and Identification Of Construction Safety Hazards and Accidents. Automation In Construction, 113.
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Abstract
As the construction industry experiences a high rate of casualties and significant economic loss associated with accidents, safety has always been a primary concern. In response, several studies have attempted to develop new approaches and state-of-the-art technology for conducting autonomous safety surveillance of construction work zones such as vision-based monitoring. The current and proposed methods including human inspection, however, are limited to consistent and real-time monitoring and rapid event recognition of construction safety issues. In addition, the health and safety risks inherent in construction projects make it challenging for construction workers to be aware of possible safety risks and hazards according to daily planned work activities. To address the urgent demand of the industry to improve worker safety, this study involves the development of an audio-based event detection system to provide daily safety issues to laborers and through the rapid identification of construction accidents. As an evidence-driven approach, the proposed framework incorporates the occupational injury and illness manual data, consisting of historical construction accident data classified by types of sources and events, into an audio-based safety event detection framework. This evidence-driven framework integrated with a daily project schedule can automatically provide construction workers with prenotifications regarding safety hazards at a pertinent work zone as well as consistently contribute to enhanced construction safety monitoring by audio-based event detection. By using a machine learning algorithm, the framework can clearly categorize the narrowed-down sound training data according to a daily project schedule and dynamically restrict sound classification types in advance. The proposed framework is expected to contribute to an emerging knowledge base for integrating an automated safety surveillance system into occupational accident data, significantly improving the accuracy of audio-based event detection.
Keywords
Construction Projects; Occupational Hazards; Construction Workers; Construction; System Safety; Video Surveillance; Work-related Injuries; Audio-based Accident Recognition; Autonomous Safety Surveillance; Construction Safety; Evidence-driven Sound Event Detection; Accident Prevention; Accidents; Audio Acoustics; Classification (of Information); Construction Industry; Health Hazards; Health Risks; Knowledge Based Systems; Learning Algorithms; Losses; Machine Learning; Monitoring; Motion Compensation; Occupational Diseases; Steel Beams And Girders; Audio-based; Construction Accidents; Construction Work Zones; Historical Construction; Sound Event Detection; State-of-the-art Technology; Vision Based Monitoring; Algorithm; System
Shakouri, Mahmoud; Lee, Hyun Woo; Choi, Kunhee. (2015). PACPIM: New Decision-Support Model of Optimized Portfolio Analysis for Community-Based Photovoltaic Investment. Applied Energy, 156, 607 – 617.
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Abstract
Inherent in large-scale photovoltaic (PV) investments is volatility that stems from a unique set of spatial factors, such as shading, building orientation, and roof slope, which can significantly affect both the level of risk and the return on investment. In order to systematically assess and manage the volatility, this study seeks to create a quantitative decision-support model: Portfolio Analysis for Community-based PV Investment Model (PACPIM). Focusing on residential PV systems, PACPIM determines optimized portfolios by applying the Mean Variance Portfolio theory. The model is intended to play an instrumental role in: (1) maximizing the hourly electricity output of PV systems; (2) minimizing the hourly volatility in electricity output; and (3) optimizing the risk-adjusted performance of community-based PV investment. The application and framework of PACPIM were deployed with an actual residential community consisting of 24 houses and their simulated data utilizing PVWatts (R) for estimating hourly electricity production. Results reveal that the optimized portfolios developed by PACPIM (1) increased annual electricity output of PV systems by 4.6%; (2) reduced the volatility in electricity output by 4.3%; and (3) offered the highest risk-adjusted performance among all possible portfolios based on the Sharpe ratios. This study is expected to effectively assist project owners and investors in systematically assessing their community-based PV projects and in developing optimized investment strategies. (C) 2015 Elsevier Ltd. All rights reserved.
Keywords
Photovoltaic Cells; Rate Of Return; Electricity; Dwellings; Electric Utilities; Community-based Investments; Decision-support Model; Mean–variance Portfolio Theory; Residential Photovoltaic Systems; Solar Energy; Decision Support Systems; Investment; Photovoltaic Power Systems; Large-scale Photovoltaic Investments; Spatial Factors; Shading; Building Orientation; Roof Slope; Return On Investment; Quantitative Decision-support Model; Portfolio Analysis For Community-based Pv Investment Model; Pacpim; Residential Pv Systems; Mean-variance Portfolio Theory; Hourly Electricity Output; Hourly Volatility; Risk-adjusted Performance; Hourly Electricity Production Estimation; Community-based Pv Projects; Optimized Investment Strategies; Romanian National Strategy; Renewable Energy; Public-attitudes; Wind Power; Pv Module; Performance; Implementation; Efficiency; Form; Economic Theory; Electricity Generation; Models; Risk; Shade; Solar Collectors
Nnaji, Chukwuma; Gambatese, John; Lee, Hyun Woo; Zhang, Fan. (2020). Improving Construction Work Zone Safety Using Technology: A Systematic Review of Applicable Technologies. Journal Of Traffic And Transportation Engineering (english Edition), 7(1), 61 – 75.
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Abstract
Once considered conventional, the construction industry is gradually increasing its reliance on innovations such as the application of technologies in safety management. Given the growing literature on technology applications in safety management and the varying opinions on the utility of applied technologies, a systematic review that streamlines findings from past studies is indispensable to construction stakeholders. Although a number of review studies are available in the building construction sector, the level of fragmentation and uniqueness within the construction industry necessitates a review study specifically targeting the heavy civil sector. In response, the present study applies a three-step approach to identify and review articles pertinent to the safety of highway construction work zones. The factors considered include the number of publications per year, publication locations, and technology types. In addition, the present study proposes to broadly group work zone safety technologies (WZSTs) into three categories based on their primary purpose: speed reduction systems, intrusion prevention and warning systems, and human-machine-interaction detection systems. Key findings include WZST research trends, application of smart work zone systems, and the potential relationship between WZSTs and fatalities. The paper ends with the identification of six additional research areas aimed at deepening the understanding of technology's role in highway safety management. The trend analysis and an in-depth discussion of each technology category alongside the identified research gaps will provide a substantial informative body of knowledge that both benefits current practitioners and directs researchers towards potential future studies. (C) 2019 Periodical Offices of Changan University. Publishing services by Elsevier B.V. on behalf of Owner.
Keywords
Automated Speed Enforcement; Drivers Visual Performance; Rumble Strips; Message Signs; Radar; Management; Adoption; Crashes; Transportation; Work Zone; Worker Safety; Technology Application; Safety Technology; Systematic Review
Choi, Kunhee; Lee, Hyun Woo. (2016). Deconstructing the Construction Industry: A Spatiotemporal Clustering Approach to Profitability Modeling. Journal Of Construction Engineering And Management, 142(10).
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Abstract
In spite of the strong influence of the construction industry on the national health of the United States' economy, very little research has specifically aimed at evaluating the key performance parameters and trends (KPPT) of the industry. Due to this knowledge gap, concerns have been constantly raised over lack of accurate measures of KPPT. To circumvent these challenges, this study investigates and models the macroeconomic KPPT of the industry through spatiotemporal clustering modeling. This study specifically aims to analyze the industry in 14 of its subsectors and subsequently, by 51 geographic spatial areas at a 15-year temporal scale. KPPT and their interdependence were firstly examined by utilizing the interpolated comprehensive U.S. economic census data. A hierarchical spatiotemporal clustering analysis was then performed to create predictive models that can reliably determine firm's profitability as a function of the key parameters. Lastly, the robustness of the predictive models was tested by a cross-validation technique called the predicted error sum of square. This study yields a notable conclusion that three key performance parameterslabor productivity, gross margin, and labor wageshave steadily improved over the study period from 1992 to 2007. This study also reveals that labor productivity is the most critical factor; the states and subsectors with the highest productivity are the most profitable. This study should be of value to decision-makers when plotting a roadmap for future growth and rendering a strategic business decisions.
Keywords
Construction Industry; Decision Making; Knowledge Management; Labour Resources; Macroeconomics; Organisational Aspects; Productivity; Profitability; Salaries; Statistical Analysis; Strategic Planning; Hierarchical Spatiotemporal Clustering Approach; National Health; Macroeconomic Kppt; Knowledge Gap; Spatiotemporal Clustering Modeling; Interpolated Comprehensive U.s. Economic Census Data; Parameters-labor Productivity; Gross Margin; Labor Wages; Strategic Business Decisions; Deconstructing; Key Performance Parameters And Trends; Firms Profitability; Error Sum Of Square; Labor Productivity; Projects; Firms; Performance; Performance Measurement; Cluster Analysis; Economic Census; Project Planning And Design
Nnaji, Chukwuma; Karakhan, Ali A.; Gambatese, John; Lee, Hyun Woo. (2020). Case Study to Evaluate Work-Zone Safety Technologies in Highway Construction. Practice Periodical On Structural Design And Construction, 25(3).
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Abstract
The construction industry is known for its conservative approach toward adopting new, emerging technologies. This conservative approach for adopting technology is caused by multiple factors including the lack of adequate resources to guide construction practitioners in the process of evaluating whether a construction firm should adopt a certain technology or not. Previous studies have already proposed rigorous protocols for evaluating work-zone technologies, but the implementation of such protocols is still unclear to many construction practitioners. The objective of this study is to provide a case study example of how evaluation protocols can be used in practice to determine whether a firm should adopt a certain work-zone technology. The case study focused on assessing the usefulness of commercially available work-zone intrusion alert technologies (WZIATs). The results of the evaluation revealed that some WZIATs could be more attractive to construction organizations and agencies in terms of providing louder alarms, being more mobile, and allowing a higher transmission range. The case study example discussed in this study is expected to provide invaluable practical information to practitioners in the construction industry interested in evaluating and adopting emerging technologies.
Keywords
Construction Industry; Mobile Radio; Occupational Safety; Road Building; Road Safety; Highway Construction; Conservative Approach; Construction Practitioners; Construction Firm; Rigorous Protocols; Work-zone Technology; Case Study Example; Evaluation Protocols; Commercially Available Work-zone Intrusion Alert Technologies; Construction Organizations; Evaluate Work-zone Safety Technologies; Speed; Signs; Work Zone; Safety Technology; Intrusion Alert; Evaluation Protocol
Choi, Kunhee; Lee, Hyun Woo; Bae, Junseo; Bilbo, David. (2016). Time-Cost Performance Effect of Change Orders from Accelerated Contract Provisions. Journal Of Construction Engineering And Management, 142(3).
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Abstract
Accelerated contract provisions (ACPs) such as cost-plus-time (A+B) and incentives/disincentives (I/D) are increasingly common, yet very little is known about their pure time-cost performance effects on change orders. To fill this large knowledge gap, a two-stage research methodology drawing on 1,372 highway improvement projects completed in California was adopted for this study. The Stage I study investigated the marginal change-order impacts of two ACPs, pure A+B and I/D combined with A+B. How ACP change orders affect projects' time-cost performance was numerically modeled and successfully validated over the Stage II study. The results clearly showed that both ACPs led to more schedule-change and cost-change orders than conventionally contracted projects, whereas I/D combined with A+B performed significantly better than pure A+B in terms of the magnitude of schedule-change orders. This conveys an important recommendation to state transportation agencies (STAs) that A+B be used with an I/D provision. The results and numerical models of this study would help STAs better assess and justify the impact of change orders on the duration and cost of projects, enabling them to more effectively use contingency amounts. Use of the models can also benefit contractors requesting a change order because the models can provide them with advanced knowledge of the probable time-cost growth rates specifically for the pursued ACP. (C) 2015 American Society of Civil Engineers.
Keywords
Construction Industry; Contracts; Costing; Incentive Schemes; Numerical Analysis; Order Processing; Performance Evaluation; Roads; Scheduling; Time Management; Transportation; Projects Time-cost Performance Effect; Cost-change Order; Accelerated Contract Provision; Knowledge Gap; California; Acp; Schedule-change Order; State Transportation Agency; Numerical Model; Sta; Incentive; Highway Improvement Project; Labor Productivity; Construction; Impact; Model; Projects; Change Order; Highway Rehabilitation; Decision Modeling; Regression; Validation; Contracting
Rodriguez, Barbara X.; Huang, Monica; Lee, Hyun Woo; Simonen, Kathrina; Ditto, Jim. (2020). Mechanical, Electrical, Plumbing and Tenant Improvements over the Building Lifetime: Estimating Material Quantities and Embodied Carbon for Climate Change Mitigation. Energy And Buildings, 226.
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Abstract
The building industry is expanding its ability to mitigate the environmental impacts of buildings through the application of life cycle assessment (LCA). Most building LCA studies focus on core and shell (C&S) and rarely assess mechanical, electrical, and plumbing (MEP) and tenant improvements (TI). However, C&S typologies in the commercial sector pose particular challenges to achieving net zero carbon due to the numerous renovations these building undergo through during their service life. MEP and TI are installed multiple times over the lifetime of commercial buildings leading to cumulative environmental impact caused by increasing material quantities and embodied carbon (EC). This study aimed to establish a preliminary range of material quantities and embodied carbon impacts for MEP and TI components, focusing on commercial office buildings in the Pacific Northwest. The first research stage involved quantifying material quantities while a second stage aimed to calculate Embodied Carbon Coefficients (ECC) and LCA impacts using different data sources. The embodied carbon estimates ranged from 40 to 75 kg CO(2)e/m(2) for MEP and 45-135 kg CO(2)e/m(2) for TI. However, with recurring instalments during a life span of 60 years the impacts become comparable to known impacts of core and shell systems. (C) 2020 Elsevier B.V. All rights reserved.
Keywords
Embodied Carbon; Life Cycle Assessment; Tenant Improvement; Mechanical; Electrical And Plumbing