Louis Luangkesorn | University of Pittsburgh (original) (raw)
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Papers by Louis Luangkesorn
Naval Research Logistics, 2007
Reliability Engineering & System Safety
Permission is given to duplicate this electronic document for personal use only, as long as it is... more Permission is given to duplicate this electronic document for personal use only, as long as it is unaltered and complete. Copies may not be duplicated for commercial purposes. Unauthorized posting of RAND PDFs to a non-RAND Web site is prohibited. RAND PDFs are protected under copyright law. For information on reprint and linking permissions, please visit the RAND Permissions page. ... The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the ...
Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid response to ... more Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid response to customers demands. Assemble-to-Order systems are a type of hybrid PTS/PTO system that enables a manufacturer to provide service to a wide range of demands while keeping a low inventory of components. We study Assemble-to-Order systems with flexible customers. Flexible customers are customers who may accept alternative products if the originally requested product is not available. We develop new performance measures and explore the impact of customer flexibility on system profit and service level. We then develop an iterative decomposition heuristic to analyze large Assemble-to-Order systems. We describe how the principles of our decomposition heuristic can be extended to analyze a variety of different Assemble-to-Order systems. We finally examine the impact of advance demand information on hybrid PTO/PTS systems with scheduled and unscheduled customers. Using a numerical study we provide...
Naval Research Logistics, 2007
Skip main navigation and go to section navigation Skip main navigation and go to page content Opt... more Skip main navigation and go to section navigation Skip main navigation and go to page content Optimum graphic presentation of this site requires a modern standards-friendly browser. The browser or PDA you are using may not display exactly as intended, but you will still be ...
Journal of Statistical Computation and Simulation, 2015
ABSTRACT Developing prediction bounds for surgery duration is difficult due to the large number o... more ABSTRACT Developing prediction bounds for surgery duration is difficult due to the large number of distinct procedures. The variety of procedures at a multi-speciality surgery suite means that even with several years of historical data a large fraction of surgical cases will have little or no historical data for use in predicting case duration. Bayesian methods can be used to combine historical data with expert judgement to provide estimates to overcome this, but eliciting expert opinion for a probability distribution can be difficult. We combine expert judgement, expert classification of procedures by complexity category and historical data in a Markov Chain Monte Carlo model and test it against one year of actual surgery cases at a multi-speciality surgical suite.
Proceedings Title: Proceedings of the 2012 Winter Simulation Conference (WSC), 2012
ABSTRACT The modeling and simulation of inpatient healthcare systems comprising of multiple inter... more ABSTRACT The modeling and simulation of inpatient healthcare systems comprising of multiple interconnected units of monitored care is a challenging task given the nature of clinical practices and procedures that regulate patient flow. Therefore, any related study on the properties of patient flow should (i) explicitly consider the modeling of patient movement rules in face of congestion, and (ii) examine the sensitivity of simulation output, expressed by patient delays and diversions, over different patient movement modeling approaches. In this work, we use a high fidelity simulation model of a tertiary facility that can incorporate complex patient movement rules to investigate the challenges inherent in its employment for resource allocation tasks.
ABSTRACT Health care capacity decisions are often based on average performance metrics such as ut... more ABSTRACT Health care capacity decisions are often based on average performance metrics such as utilization. However, such decisions can be misleading, as a large portion of the costs in service operations is due to the inability to provide service due to congestion. This paper will review sources of variation that affect inpatient care capacity and develop a series of models of patient flow in a health care facility. We demonstrate that even in settings where the patient population and services provided are fixed, models that do not account for natural variations in the arrival rate and correlation in patient lengths of stay in sequential units will show the same utilization, but underestimate congestion and the resulting costs. Therefore, we argue that utilization is an inappropriate measure for validating models and congestion metrics such as blocking and diversions should be used instead.
Journal of Public Health Management and Practice, Sep 2013
Context: During the 2009 H1N1 pandemic, computational agent-based models (ABMs) were extensive... more Context:
During the 2009 H1N1 pandemic, computational agent-based models (ABMs) were extensively used to evaluate interventions to control the spread of emerging pathogens. However, evaluating different possible combinations of interventions using ABMs can be computationally very expensive and time-consuming. Therefore, most policy studies have examined the impact of a single policy decision.
Objective:
To apply a sequential experimental design method with an ABM to analyze policy alternatives composed of a combination of school closure and vaccination policies to provide a set of promising “optimal” combinations of policies to control an H1N1-type epidemic to policy makers.
Methods:
We used an open-source agent-based modeling system, FRED (A Framework for Reconstructing Epidemiological Dynamic), to simulate the spread of an H1N1 epidemic in Alleghany County, Pennsylvania, with a census-based synthetic population. We used an approach called best subset selection method to evaluate 72 alternative policies consisting of a combination of options for school closure threshold, closure duration, Advisory Committee on Immunization Practices prioritization, and second-dose vaccination prioritization policies. Using the attack rate as a performance measure, best subset selection enabled us to eliminate inferior alternatives and identify a small group of alternative policies that could be further evaluated on the basis of other criteria.
Results:
Our sequential design approach to evaluate a combination of alternative mitigation policies leads to a savings in computational effort by a factor of 2 when examining combinations of school closure and vaccination policies.
Conclusions:
Best subset selection demonstrates a substantial reduction in the computational burden of a large-scale ABM in evaluating several alternative policies. Our method also provides policy makers with a set of promising policy combinations for further evaluation based on implementation considerations or other criteria.
IIE Transactions, Jan 1, 2003
… (WSC), Proceedings of …, Jan 1, 2011
Abstract: Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid re... more Abstract: Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid response to customers demands. Assemble-to-Order systems are a type of hybrid PTS/PTO system that enables a manufacturer to provide service to a wide range of ...
…, Jan 1, 2012
Abstract Abu Dhabi Health Services (SEHA) has established Disease Prevention and Screening Center... more Abstract Abu Dhabi Health Services (SEHA) has established Disease Prevention and Screening Centers (DPSCs) to provide health screening for third-country national (TCN) workers. In anticipation of increases in the number of TCN workers who will require health screening, SEHA is building new centers to accommodate the increased requirements. As part of the design process, we used queuing and simulation models to model (1) the current DPSC configuration,(2) a configuration based on individual lanes, and (3) a configuration ...
… ), Proceedings of the …, Jan 1, 2011
Naval Research Logistics, 2007
Reliability Engineering & System Safety
Permission is given to duplicate this electronic document for personal use only, as long as it is... more Permission is given to duplicate this electronic document for personal use only, as long as it is unaltered and complete. Copies may not be duplicated for commercial purposes. Unauthorized posting of RAND PDFs to a non-RAND Web site is prohibited. RAND PDFs are protected under copyright law. For information on reprint and linking permissions, please visit the RAND Permissions page. ... The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the ...
Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid response to ... more Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid response to customers demands. Assemble-to-Order systems are a type of hybrid PTS/PTO system that enables a manufacturer to provide service to a wide range of demands while keeping a low inventory of components. We study Assemble-to-Order systems with flexible customers. Flexible customers are customers who may accept alternative products if the originally requested product is not available. We develop new performance measures and explore the impact of customer flexibility on system profit and service level. We then develop an iterative decomposition heuristic to analyze large Assemble-to-Order systems. We describe how the principles of our decomposition heuristic can be extended to analyze a variety of different Assemble-to-Order systems. We finally examine the impact of advance demand information on hybrid PTO/PTS systems with scheduled and unscheduled customers. Using a numerical study we provide...
Naval Research Logistics, 2007
Skip main navigation and go to section navigation Skip main navigation and go to page content Opt... more Skip main navigation and go to section navigation Skip main navigation and go to page content Optimum graphic presentation of this site requires a modern standards-friendly browser. The browser or PDA you are using may not display exactly as intended, but you will still be ...
Journal of Statistical Computation and Simulation, 2015
ABSTRACT Developing prediction bounds for surgery duration is difficult due to the large number o... more ABSTRACT Developing prediction bounds for surgery duration is difficult due to the large number of distinct procedures. The variety of procedures at a multi-speciality surgery suite means that even with several years of historical data a large fraction of surgical cases will have little or no historical data for use in predicting case duration. Bayesian methods can be used to combine historical data with expert judgement to provide estimates to overcome this, but eliciting expert opinion for a probability distribution can be difficult. We combine expert judgement, expert classification of procedures by complexity category and historical data in a Markov Chain Monte Carlo model and test it against one year of actual surgery cases at a multi-speciality surgical suite.
Proceedings Title: Proceedings of the 2012 Winter Simulation Conference (WSC), 2012
ABSTRACT The modeling and simulation of inpatient healthcare systems comprising of multiple inter... more ABSTRACT The modeling and simulation of inpatient healthcare systems comprising of multiple interconnected units of monitored care is a challenging task given the nature of clinical practices and procedures that regulate patient flow. Therefore, any related study on the properties of patient flow should (i) explicitly consider the modeling of patient movement rules in face of congestion, and (ii) examine the sensitivity of simulation output, expressed by patient delays and diversions, over different patient movement modeling approaches. In this work, we use a high fidelity simulation model of a tertiary facility that can incorporate complex patient movement rules to investigate the challenges inherent in its employment for resource allocation tasks.
ABSTRACT Health care capacity decisions are often based on average performance metrics such as ut... more ABSTRACT Health care capacity decisions are often based on average performance metrics such as utilization. However, such decisions can be misleading, as a large portion of the costs in service operations is due to the inability to provide service due to congestion. This paper will review sources of variation that affect inpatient care capacity and develop a series of models of patient flow in a health care facility. We demonstrate that even in settings where the patient population and services provided are fixed, models that do not account for natural variations in the arrival rate and correlation in patient lengths of stay in sequential units will show the same utilization, but underestimate congestion and the resulting costs. Therefore, we argue that utilization is an inappropriate measure for validating models and congestion metrics such as blocking and diversions should be used instead.
Journal of Public Health Management and Practice, Sep 2013
Context: During the 2009 H1N1 pandemic, computational agent-based models (ABMs) were extensive... more Context:
During the 2009 H1N1 pandemic, computational agent-based models (ABMs) were extensively used to evaluate interventions to control the spread of emerging pathogens. However, evaluating different possible combinations of interventions using ABMs can be computationally very expensive and time-consuming. Therefore, most policy studies have examined the impact of a single policy decision.
Objective:
To apply a sequential experimental design method with an ABM to analyze policy alternatives composed of a combination of school closure and vaccination policies to provide a set of promising “optimal” combinations of policies to control an H1N1-type epidemic to policy makers.
Methods:
We used an open-source agent-based modeling system, FRED (A Framework for Reconstructing Epidemiological Dynamic), to simulate the spread of an H1N1 epidemic in Alleghany County, Pennsylvania, with a census-based synthetic population. We used an approach called best subset selection method to evaluate 72 alternative policies consisting of a combination of options for school closure threshold, closure duration, Advisory Committee on Immunization Practices prioritization, and second-dose vaccination prioritization policies. Using the attack rate as a performance measure, best subset selection enabled us to eliminate inferior alternatives and identify a small group of alternative policies that could be further evaluated on the basis of other criteria.
Results:
Our sequential design approach to evaluate a combination of alternative mitigation policies leads to a savings in computational effort by a factor of 2 when examining combinations of school closure and vaccination policies.
Conclusions:
Best subset selection demonstrates a substantial reduction in the computational burden of a large-scale ABM in evaluating several alternative policies. Our method also provides policy makers with a set of promising policy combinations for further evaluation based on implementation considerations or other criteria.
IIE Transactions, Jan 1, 2003
… (WSC), Proceedings of …, Jan 1, 2011
Abstract: Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid re... more Abstract: Hybrid Produce-to-Stock/Produce-to-Order (PTS/PTO) systems are used to provide rapid response to customers demands. Assemble-to-Order systems are a type of hybrid PTS/PTO system that enables a manufacturer to provide service to a wide range of ...
…, Jan 1, 2012
Abstract Abu Dhabi Health Services (SEHA) has established Disease Prevention and Screening Center... more Abstract Abu Dhabi Health Services (SEHA) has established Disease Prevention and Screening Centers (DPSCs) to provide health screening for third-country national (TCN) workers. In anticipation of increases in the number of TCN workers who will require health screening, SEHA is building new centers to accommodate the increased requirements. As part of the design process, we used queuing and simulation models to model (1) the current DPSC configuration,(2) a configuration based on individual lanes, and (3) a configuration ...
… ), Proceedings of the …, Jan 1, 2011