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Multi-objective two-stage stochastic optimization model for post-disaster waste management

Boonmee Chawis, Legsakul Komkrit, Arimura Mikiharu

Production Engineering Archives

2023

Vol. 29, Iss. 1

58--68

Post-disaster waste management is one of the most crucial tasks in the recovery phase of the disaster cycle, and it was created to assist affected communities in returning to a stable state following a disaster. To develop an efficient post-disaster waste management strategy, this study presents a multi-objective two-stage stochastic mixed integer linear programming model for post-disaster waste management. The proposed mathematical model was developed based on a mixed strategy of on-site and off-site waste separation in the supply chain. This study aims to minimize not only the total cost and the environmental impact to provide waste flow decisions and choose collection and separation sites, recycling sites, landfill sites, and incineration sites throughout the supply chain under the uncertain situation. To solve a multi-objective problem, a normalized weighted sum method is used to find the solution. A numerical case based on realistic data is presented to validate and verify the proposed model. Based on the numerical example, the results demonstrated that the implementation of the mixed strategy for waste separation with the consideration of uncertain situations can reduce the total cost, balance the environmental impact, and determine the unexpected situation in the post-disaster waste supply chain efficiently.

Layout design of outpatient department: simulation study and implementation

Boonmee Chawis, Kasemset Chompoonoot, Phongthiya Tinnakorn

LogForum

2022

Vol. 18, no. 2

185--196

Background: Hospital layout is one important factor affecting hospital service quality and, consequently, patient satisfaction. Generally, the layout is designed based on the experience of the hospital specialists without any systematic approaches. Purpose: Due to the increasing number of patients, the case study hospital has built a new multi-floor building to move its Outpatient Department (OPD) to operate there. Therefore, this study aims to apply the Activity Relationship Analysis (ARA) and simulation to design a new OPD layout. Methodology: Data of the previous system were analyzed using the ARA. The results were then used to design three scenarios (A, C, and D) and the other three scenarios (B, E, and F) were proposed by hospital specialists. Then, six layouts were evaluated using simulation tests and the efficiencies of the designs were measured by an average total service time per patient. Results: The simulation results showed that the average total service time of scenario A, D, E, and F were lower than scenario B and C. While the average total service time at the sub-service unit of D was the longest compared to scenario A, E, and F. These results demonstrated that scenario A, E, and F were the most efficient layouts. However, when considered thoroughly by the hospital specialists, scenario A was eventually selected. Conclusion: This study can contribute to scientific literature as it demonstrates the application of the ARA and simulation in the design of the multi-floor layout, an aspect under-researched in existing studies. This study also provides the practical implication suggesting that these techniques should be used together in the layout designs because they can help to determine the correctness and efficiency of the layout design before actual implementation.