Kim, Jonghyeob; Han, Sangwon; Hyun, Chang-taek. (2019). Identification and Reduction of Synchronous Replacements in Life-Cycle Cost Analysis of Equipment. Journal Of Management In Engineering, 35(1).
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Abstract
Life-cycle cost analysis (LCCA) is a methodology used to calculate the total cost of a project from initial planning to final disposal. In conventional approaches, LCCA assumes that regular and preventive maintenance will be performed according to each replacement cycle for individual components, and replacement for each component is considered independently. However, because the components of equipment used in buildings are installed systemically, replacements of major components may cause unexpected replacements of dependent minor components. Therefore, it is necessary to identify additional replacements based on the associations among these related replacement components to achieve a more reliable LCCA. In response, this study proposes an LCCA model that comprehensively considers the relationships among the maintenance components. The development of the model involves identifying relationships among components using social network analysis (SNA), arranging individual replacement timings of the components that reflect these relationships, and analyzing the life-cycle cost (LCC) based on the arranged timing. To validate the model, its applicability and effectiveness was illustrated and tested using 19 components of a rainwater reuse system. This study makes a theoretical contribution to the body of knowledge by suggesting concepts of synchronous relationships and replacements based on SNA. In addition, the use of the model proposed in this study enables practitioners to analyze LCCs that reflect synchronous replacements, which allows more reasonable decision-making considering hidden costs in conventional LCC. (C) 2018 American Society of Civil Engineers.
Keywords
Decision Making; Life Cycle Costing; Preventive Maintenance; Synchronous Replacements; Life-cycle Cost Analysis; Lcca Model; Maintenance Components; Social Network Analysis; Painted Surfaces; Decision-making; Prediction; Model; Risk; Maintenance; Replacement; Synchronous Replacement; Synchronous Relationship; Life-cycle Cost Analysis (lcca); Social Network Analysis (sna)
Habibnezhad, Mahmoud; Puckett, Jay; Jebelli, Houtan; Karji, Ali; Fardhosseini, Mohammad Sadra; Asadi, Somayeh. (2020). Neurophysiological Testing for Assessing Construction Workers’ Task Performance at Virtual Height. Automation In Construction, 113.
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Abstract
Falling from heights is the primary cause of death and injuries at construction sites. As loss of balance has a fundamental effect on falling, it is important to understand postural regulation behavior during construction tasks at heights, especially those that require precise focus in an upright standing position (therefore, a dual-task demand on focus). Previous studies examined body sway during a quiet stance and dual tasks to understand latent factors affecting postural balance. Despite the success of these studies in discovering underlying factors, they lack a comprehensive analysis of a task's simultaneous cognitive load, postural sway, and visual depth. To address this limitation, this paper aims to examine construction workers' postural stability and task performance during the execution of visual construction tasks while standing upright on elevated platforms. To that end, two non-intrusive neurophysiological tests, a hand-steadiness task (HST) and a pursuit task (PT), were developed for construction tasks in a virtual environment (VE) as performance-based means to assess the cognitive function of workers at height. Workers' postural stability was measured by recording the mapped position of the Center of Pressure (COP) of the body on a posturography force plate, and the postural sway metrics subsequently calculated. A laboratory experiment was designed to collect postural and task performance data from 18 subjects performing the two batteries of tests in the virtual environment. The results demonstrated a significant decrease in the Root-Mean Square (RMS) of COP along the anterior-posterior axis during the Randomized Pursuit Task (RPT) and maximum body sway of the center of pressure (COP) in the mediolateral direction during both tests. Also, subjects exposed to high elevation predominately exhibit higher accuracy for RPT (P-value = 0.02) and lower accuracy for HST (P-value = 0.05). The results show that the combination of elevation-related visual depth and low-complexity dual tasks impairs task performance due to the elevation-induced visual perturbations and anxiety-driven motor responses. On the other hand, in the absence of visual depth at height, high task complexity surprisingly improves the pursuit tracking performance. As expected, during both tasks, alterations in postural control were manifested in the form of a body sway decrement as a compensatory postural strategy for accomplishing tasks at high elevation.
Keywords
Task Performance; Construction Workers; Test Design; Cognitive Load; Standing Position; Sitting Position; Neurophysiological Test; Postural Stability; Virtual Reality; Workers' Safety At Height; Fall-risk; Reaction-time; Fear; Real; Acrophobia; Balance; Safety
The Aga Khan Award for Architecture (AKAA) recently announced 20 shortlisted projects for the 2022 Award cycle. The projects will compete for a share of the US$ 1 million prize, one of the largest in architecture. The 20 shortlisted projects were selected by an independent Master Jury from a pool of 463 projects nominated for the 15th Award Cycle (2020-2022). The Aga Khan Award for Architecture was established by His Highness the Aga Khan in 1977 to identify and encourage…
ARPA-E announced $5 million in funding to two universities—the University of Washington and University of California, Davis—working to develop life cycle assessment tools and frameworks associated with transforming buildings into net carbon storage structures. The funding is part of the Harnessing Emissions into Structures Taking Inputs from the Atmosphere (HESTIA) Exploratory Topic. Parametric Open Data for Life Cycle Assessment (POD | LCA) – $3,744,303 The University of Washington’s Carbon Leadership Forum will develop a rigorous and flexible parametric Life Cycle Assessment (LCA)…
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Ken Tadashi Oshima is Professor in the Department of Architecture at the University of Washington, Seattle, where he teaches trans-national architectural history, theory and design. He has also been a visiting professor at the Harvard Graduate School of Design and UCLA, and has taught at Columbia University and the University of British Columbia. He earned an AB degree, magna cum laude, in East Asian studies and visual and environmental studies from Harvard College, an MArch degree from University of California,…
Research Interests: Designing built environments to enhance human happiness, and related principles: Justice, Nature Integration, Access, Identity, Well-Being, Resiliency.
My research interests are in lean construction principles with a focus on lean project delivery systems, offsite and prefabrication construction, construction supply chain networks, and target value design. In addition to that my interests include life cycle project economics and modeling, building economic and quantitative risk analysis, a public-private partnership for projects, value engineering and management, and new technologies in construction.
I am interested in research related to emerging technology in the AEC industry, and looking for opportunities to conduct experiment-based research whenever possible, particularly research related to virtual construction or construction safety. I have additional interests in public-private partnerships, lean construction, and project delivery.