Kim, Tae-hyung; Lee, Hyun Woo; Hong, Seok-woo. (2016). Value Engineering for Roadway Expansion Project over Deep Thick Soft Soils. Journal Of Construction Engineering And Management, 142(2).
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Abstract
A roadway expansion that takes place on soft ground is susceptible to differential settlement because of the high consolidation of soft soils. Therefore, steps must be taken to lessen the risk of such settlement; yet, this often only results in costly drainage solutions. In that, applying a systematic value engineering (VE) process can be beneficial to develop cost-effective design alternatives. However, VE studies specifically targeting for this problem are absent from the field. Thus, the goal of this study is to supplement this knowledge gap by applying a systematic VE process to an expansion project on soft ground to demonstrate the benefits of performing VE. A case study was performed on an expansion project over a soft soil layer approximately 50m thick. Through the VE process, the original design was reviewed, problems were discussed, and three alternatives were proposed. Then value analysis techniques were applied to evaluate these alternatives in terms of cost saving, function improvement, and value improvement with respect to the original design. The VE process and design alternatives as applied in this study are expected to serve as a guideline for engineers and decision-makers in roadway expansion projects on soft ground. (C) 2015 American Society of Civil Engineers.
Keywords
Construction Industry; Costing; Project Management; Road Building; Soil; Value Engineering; Engineers; Decision-makers; Value Improvement; Function Improvement; Knowledge Gap; Cost-effective Design; Deep Thick Soft Soils; Soft Ground; Roadway Expansion Project; Systematic Value Engineering Process; Value Engineering (ve); Job Plan; Roadway Expansion; Deep Soft Ground; Differential Settlement; Cost Saving; Project Planning And Design
Choi, Kunhee; Bae, Junseo; Yin, Yangtian; Lee, Hyun Woo. (2021). Act(2): Time Cost Tradeoffs from Alternative Contracting Methods. Journal Of Management In Engineering, 37(1).
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Abstract
Incentive/disincentive (I/D) and cost-plus-time (A+B) are two of the most widely used alternative contracting methods (ACMs) for accelerating the construction of highway infrastructure improvement projects. However, little is known about the effects of trade-offs in terms of project schedule and cost performance. This study addresses this problem by creating and testing a stochastic decision support model called accelerated alternative contracting cost-time trade-off (ACT(2)). This model was developed by a second-order polynomial regression analysis and validated by the predicted error sum of square statistic and paired comparison tests. The results of a descriptive trend analysis based on a rich set of high-confidence project data show that I/D is effective at reducing project duration but results in higher cost compared to pure A+B and conventional methods. This cost-time trade-off effect was confirmed by the ACT(2) model, which determines the level of cost-time trade-off for different ACMs. This study will help state transportation agencies promote more effective application of ACMs by providing data-driven performance benchmarking results when evaluating competing acceleration strategies and techniques. (C) 2020 American Society of Civil Engineers.
Keywords
Highway; Construction; Model; Alternative Contracting Methods; Cost-plus-time; A Plus B; Incentive; Infrastructure Trend; Time-cost Trade-off
Shakouri, Mahmoud; Lee, Hyun Woo. (2016). Mean-Variance Portfolio Analysis Data For Optimizing Community-Based Photovoltaic Investment. Data In Brief, 6, 840 – 842.
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Abstract
The amount of electricity generated by Photovoltaic (PV) systems is affected by factors such as shading, building orientation and roof slope. To increase electricity generation and reduce volatility in generation of PV systems, a portfolio of PV systems can be made which takes advantages of the potential synergy among neighboring buildings. This paper contains data supporting the research article entitled: PACPIM: new decision-support model of optimized portfolio analysis for community-based photovoltaic investment [1]. We present a set of data relating to physical properties of 24 houses in Oregon, USA, along with simulated hourly electricity data for the installed PV systems. The developed Matlab code to construct optimized portfolios is also provided in Supplementary materials. The application of these files can be generalized to variety of communities interested in investing on PV systems. (C) 2016 The Authors. Published by Elsevier Inc.
Keywords
Community Solar; Photovoltaic System; Portfolio Theory; Energy Optimization; Electricity Volatility
Su, Shu; Li, Xiaodong; Zhu, Chen; Lu, Yujie; Lee, Hyun Woo. (2021). Dynamic Life Cycle Assessment: A Review of Research for Temporal Variations in Life Cycle Assessment Studies. Environmental Engineering Science, 38(11), 1013 – 1026.
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Abstract
Life cycle assessment (LCA) is a comprehensive and important environmental management tool around the world. However, lacking temporal information has been a major challenge. In the past decade, dynamic LCA (DLCA), which incorporates temporal variations into assessment, has been an emerging research topic with increasing publications. A timely comprehensive review is needed to present current progress and discuss future directions. This article reviews 144 DLCA articles quantitatively and qualitatively. A bibliometric approach is adopted to conduct co-occurrence analysis and cluster analysis of DLCA studies. The research progress, approaches, and limitations of three temporal variation types (i.e., dynamic life cycle inventory, dynamic characterization factors, and dynamic weighting factors) in DLCA studies are systematically analyzed and discussed. It is concluded that: (1) dynamic inventory analysis is usually conducted by collecting time-differentiated data at each time step. Field monitoring, simulation, scenario analysis, and prediction based on historical data are common approaches. (2) Dynamic characterization studies primarily focus on two impact categories: global warming and toxicity. More studies are in need. (3) Various methods and indicators (i.e., dynamic pollution damage cost, temporal environmental policy targets, and discount rates) are used to solve the dynamic weighting issue, and they have specific limitations. Finally, three interesting topics are discussed: comparison between dynamic and static results, the large data amount issue, and the trend of tools development. This review offers a holistic view on temporal variations in DLCA studies and provides reference and directions for future dynamic studies.
Keywords
Literature Reviews; Cluster Analysis (statistics); Global Warming; Environmental Management; Discount Prices; Emission Inventories; Dynamic Characterization; Dynamic Inventory Analysis; Dynamic Weighting; Environmental Impact; Life Cycle Assessment; Temporal Variation; Cluster Analysis; Life Cycle; 'current; Dynamic Inventory Analyse; Dynamic Lca; Environmental Management Tool; Inventory Analysis; Research Topics; Temporal Information; Dependent Climate Impact; Greenhouse-gas Emission; Biogenic Carbon; Assessment Framework; Fresh-water; Electricity-generation; Energy Efficiency; Wheat Production; Embodied Energy; Time
Gambatese, John A.; Pestana, Catarina; Lee, Hyun Woo. (2017). Alignment between Lean Principles and Practices and Worker Safety Behavior. Journal Of Construction Engineering And Management, 143(1).
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Abstract
Alignment and synergy between the areas of lean construction and safety management are expected because all near misses and injury incidents represent waste from the lean perspective. This paper describes a research study of lean and safety principles and practices with regards to worker behavior and safety practices. Specifically, the study aimed to investigate the extent of alignment between lean construction principles/practices and worker behaviors associated with construction safety. To conduct the study, the researchers used a multistep process involving a comprehensive literature review, document content analyses by an expert panel, and a survey of industry practitioners knowledgeable about lean construction. The findings support the perspective that many similarities exist between the application and impacts of lean and safety principles and practices. Lean practitioners surveyed believe that implementation of the last planner system as a lean practice is most beneficial to the following safety practices: management commitment, preproject planning, and pretask planning. The present study revealed that lean principles and practices can provide a valuable opportunity to further improve construction worker safety; however, the findings show that there is a difference between lean construction and safety management practices, revealing a gap with respect to worker behavior. Understanding and eliminating this gap is important for the industry to realize the full benefit that lean principles and practices can have on worker safety. To do so, the authors suggest expanding lean practices to further directly engage field workers and address worker behavior issues along with carefully communicating the lean message to construction personnel. (C) 2016 American Society of Civil Engineers.
Keywords
Construction Industry; Injuries; Lean Production; Occupational Safety; Planning; Lean Principles; Lean Construction; Safety Management Practices; Injury Incidents; Worker Behaviors; Construction Safety; Document Content Analysis; Management Commitment; Preproject Planning; Pretask Planning; Construction Worker Safety Behavior; Construction Accident Causality; Risk; Lean Design; Worker Behavior; Safety; Labor And Personnel Issues
Choi, Suji; Kim, Soyeon; Kwak, Mingi; Park, Jaewan; Park, Subin; Kwak, Dongjoon; Lee, Hyun Woo; Lee, Sangwon. (2022). Would You Trust Driverless Service? Formation Of Pedestrian’s Trust And Attitude Using Non-verbal Social Cues. Sensors (14248220), 22(7).
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Abstract
Despite the widespread application of Autonomous Vehicles (AV) to various services, there has been relatively little research carried out on pedestrian-AV interaction and trust within the context of service provided by AV. This study explores the communication design strategy promoting a pedestrian's trust and positive attitude to driverless services within the context of pedestrian-AV interaction using non-verbal social cues. An empirical study was conducted with an experimental VR environment to measure participants' intimacy, trust, and brand attitude toward AV. Further understanding of their social interaction experiences was explored through semi-structured interviews. As a result of the study, the interaction effect of social cues was found, and it was revealed that brand attitude was formed by the direct effects of intimacy and trust as well as the indirect effects of intimacy through trust's mediation. Furthermore, 'Conceptual Definition of Space' was identified to generate differences in the interplay among intimacy, trust, and brand attitude according to social cues. Quantitative and qualitative results were synthesized to discuss implications considering the service context. Practical implications were also addressed suggesting specific design strategies for utilizing the sociality of AV.
Keywords
Pedestrians; Nonverbal Cues; Consumer Attitudes; Social Attitudes; Social Interaction; Attitude (psychology); Autonomous Vehicles; Brand Attitude; Driverless Service; Intimacy; Pedestrian–av Interaction; Social Cues; Trust; Pedestrian-av Interaction; Conversational Agent; Brand Experience; Impact; Automation; Perception; Disclosure; Style; Gaze
Shakouri, Mahmoud; Lee, Hyun Woo; Kim, Yong-woo. (2017). A Probabilistic Portfolio-Based Model for Financial Valuation of Community Solar. Applied Energy, 191, 709 – 726.
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Abstract
Community solar has emerged in recent years as an alternative to overcome the limitations of individual rooftop photovoltaic (PV) systems. However, there is no existing model available to support probabilistic valuation and design of community solar based on the uncertain nature of system performance over time. In response, the present study applies the Mean-Variance Portfolio Theory to develop a probabilistic model that can be used to increase electricity generation or reduce volatility in community solar. The study objectives include identifying the sources of uncertainties in PV valuation, developing a probabilistic model that incorporates the identified uncertainties into portfolios, and providing potential investors in community solar with realistic financial indicators. This study focuses on physical, environmental, and financial uncertainties to construct a set of optimized portfolios. Monte Carlo simulation is then performed to calculate the return on investment (ROI) and the payback period of each portfolio. Lastly, inclusion vs. exclusion of generation and export tariffs are compared for each financial indicator. The results show that the portfolio with the maximum output offers the highest ROI and shortest payback period while the portfolio with the minimum risk indicates the lowest ROI and longest payback period. This study also reveals that inclusion of tariffs can significantly influence the financial indicators, even more than the other identified uncertainties. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords
Solar Energy; Photovoltaic Power Systems; Monte Carlo Method; Market Volatility; Energy Economics; Community Solar; Monte Carlo Simulation; Photovoltaic Systems; Portfolio Theory; Uncertainty; Environmental Uncertainties; Financial Indicator; Financial Uncertainties; Physical Uncertainties; Identified Uncertainties; Probabilistic Model; Mean-variance Portfolio Theory; Probabilistic Valuation; Individual Rooftop Photovoltaic Systems; Financial Valuation; Probabilistic Portfolio-based Model; Investment; Monte Carlo Methods; Photovoltaic Cells; Risk Analysis; Tariffs; Resolution Lidar Data; Electricity Consumption; Pv Systems; Autoregressive Models; Potential Assessment; Generation Systems; Neural-networks; Energy; Buildings; Economic Theory; Electricity; Exports; Probabilistic Models; Risk
Kim, Jonghyeob; Lee, Hyun Woo; Bender, William; Hyun, Chang-taek. (2018). Model for Collecting Replacement Cycles of Building Components: Hybrid Approach of Indirect and Direct Estimations. Journal Of Computing In Civil Engineering, 32(6).
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Abstract
Building maintenance, repair, and replacement (MR&R) costs are estimated to be two to three times larger than initial construction costs. Thus, it is important to accurately estimate and manage MR&R costs in the planning phase and/or design phase of a construction project based on life cycle cost analysis (LCCA). However, the nature of LCCA requires making necessary assumptions for the prediction and analysis of MR&R costs, and the reliability of the assumptions greatly impacts LCCA results. In particular, determining reasonable replacement cycles is especially important given that each replacement typically involves a significant amount of capital. However, conventional approaches largely focus on either collecting component-specific replacement cases or surveying expert opinions, both of which reduce the usability and reliability of replacement cycle data at an early stage. To overcome these limitations, this study aims to develop a replacement cycle collection model that can expedite the data collection by combining indirect estimations with direct estimations. The development of the model involves collecting replacement cases, developing replacement cycle and index estimation methods, and developing an algorithm to implement the suggested model. As a validation, the applicability and effectiveness of the model were illustrated and tested by using simulated cases based on 21 real-world facilities. This study makes a theoretical contribution to the body of knowledge by developing a replacement cycle data collection model based on long-term and macro perspectives. The developed model will also be of value to practitioners when they try to improve the reliability of their LCCA.
Keywords
Buildings (structures); Life Cycle Costing; Maintenance Engineering; Structural Engineering; Building Components; Building Maintenance; Planning Phase; Design Phase; Construction Project; Life Cycle Cost Analysis; Replacement Cycle Data Collection Model; Construction Costs; Lcca; Maintenance Repair And Replacement Cost; Service Life Prediction; Repair; Replacement; Replacement Cycles; Replacement Index; Database; Indirect Estimations
Lee, Hyun Woo; Harapanahalli, Bharat Anand; Nnaji, Chukwuma; Kim, Jonghyeob; Gambatese, John. (2018). Feasibility of Using QR Codes in Highway Construction Document Management. Transportation Research Record, 2672(26), 114 – 123.
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Abstract
Highway construction occasionally takes place in remote locations, making its document management challenging especially when frequent document revisions occur. With the recent advancement of smartphones and tablets, Quick Response (QR) codes can provide project teams rapid and reliable access to up-to-date documents required for field operations. As a result, the use of QR codes can lead to a reduced need for traveling or meeting for document revisions, and reduce the amount of hardcopy documents and storage space. Despite the potential for significant benefits, there have been few studies aimed at assessing the feasibility of using QR codes in highway construction. In response, the objective of the study was to investigate the benefits of and barriers to using QR codes in highway construction for document management. To conduct the study, first a multi-step process was used, involving an online survey and interviews, with a goal of determining the status quo of highway construction in terms of document management and mobile information technology (IT). The results indicate that hardcopy documentation is still the most prevalent form of document management in highway construction, and hence there is an opportunity for implementing QR codes in conjunction with mobile IT. In the second part of the study, a time study using a real-world infrastructure project was conducted based on three activities: detail look up, specification check, and version check. As a result, the study found statistical evidence that using QR codes can lead to significant time savings.
Keywords
Highway Planning; Information Services; Road Construction; Document Management; Field Operation; Highway Construction; Infrastructure Project; Online Surveys; Quick Response Code; Remote Location; Statistical Evidence
Nnaji, Chukwuma; Lee, Hyun Woo; Karakhan, Ali; Gambatese, John. (2018). Developing a Decision-Making Framework to Select Safety Technologies for Highway Construction. Journal Of Construction Engineering And Management, 144(4).
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Abstract
Highway construction has consistently reported relatively high fatality rates largely because of the considerable exposure of workers to live traffic. To address this anomaly, traffic control planners are tasked with making decisions geared toward reducing hazardous situations caused by transiting vehicles and construction equipment. The growing application of technologies to enhance worker safety should be considered during the traffic control planning process. In certain cases, decisions such as choosing among technology options are made using experiential individual knowledge without the application of scientific and systematic decision-making methods. Use of experience-based decision making in this context is largely the result of sparse literature on scientific methods of selecting between alternatives in highway construction work zones. By applying the Choosing by Advantages (CBA) decision-making method, a process that achieves sound and effective decisions, the current study aims to fill the gap in practice by proposing a decision-making framework that could enhance the value-cost selection process of safety technologies in highway construction work zones. A situation that applied work zone intrusion alert technologies (WZIATs) was selected as a case study. Using a focus group session and case projects as an evaluation study process, the proposed framework based on the CBA decision-making process was applied to evaluate three WZIATs. Findings from the current study will benefit safety professionals and practitioners by providing a step-by-step approach to make sound decisions that can enhance the level of safety in highway construction work zones.
Keywords
Construction Equipment; Decision Making; Occupational Safety; Project Management; Road Building; Effective Decisions; Decision-making Framework; Value-cost Selection Process; Highway Construction Work Zones; Work Zone Intrusion Alert Technologies; Cba Decision-making Process; Sound Decisions; Traffic Control Planners; Worker Safety; Traffic Control Planning Process; Technology Options; Scientific Decision-making Methods; Systematic Decision-making Methods; Experience-based Decision Making; Advantages Decision-making Method; Safety Technologies; Knowledge; Signs