## 2 Materials and Methods
### System Simulation  
System simulation is a tool used in system design and analysis, ranging from manufacturing to service organizations. It optimizes processes, reduces waiting times, and increases efficiency and competitiveness. Simulation-based production planning can also increase productivity by streamlining work strategy time [7; 8; 9]. Transportation systems are primarily evaluated through simulation analysis, which helps in understanding traffic operation efficiency, potential problems, and improvement plans. System simulation can also assist decisionmakers in management and work research when system problems are complex and cannot be determined based on empirical methods alone. System models are classified into deterministic and stochastic, static and dynamic, and continuous and discrete [10]. Deterministic models use fixed parameters, while stochastic models consider random probability factors. Deterministic models simplify systemsor predict outcomes under fixed circumstances [11], while dynamic models consider time changes and system changes over time [12]. Continuous models change the system's state continuously over time, such as changes in water levels in a reservoir. Continuous simulation is suitable for predicting rainfall and floods, while constant models describe continuously changing systems [13]. In contrast, discrete models change state variables intermittently at specific points in time, such as in manufacturing production processes where production activities may occur intermittently [14]. Several software packages can support analysis in practical simulation applications, including FlexSim, Arena, Plant Simulation, etc. The advantage of FlexSim in simulation is that the software uses 3D objects to build models, which can be used to build models more intuitively and save time. The software can also be customized for 3D objects, including freely adjusting components, interfaces, logic, and behaviors. In addition, FlexSim can also be combined with files from other software to make the virtual production line more realistic. For example, FlexSim can import layout drawings drawn using AutoCAD, or models that can be imported into 3D drawing software such as Inventor and SolidWorks, and applied to the production line. FlexSim has powerful simulation capabilities and can simulate and analyze charts at the same time. Through the built-in dashboard in the software, graphs can be generated for various data in the model, allowing for faster analysis (Chinese Encyclopedia of FlexSim Software Introduction, 2023). Combining the above points, this study uses FlexSim simulation software for simulation analysis. The software's customizability, high-performance simulation engine, high-efficiency data analysis, and high visualization advantages meet the analysis needs of this study. There have been many studies on system simulation at home and abroad. For example, in the study [11], it was mentioned that the logistics and commodity warehousing costs of e-commerce companies in actual operations are incredibly high. When e-commerce companies introduce automated three-dimensional warehouses, FlexSim simulation software is used to model the automated storage and retrieval system (ASRS), and bottleneck analysis and optimization are carried out for the sorting and processing outflow of materials so that e-commerce companies can operate efficiently. In the research of [12], FlexSim was used to model the queuing system of the vise production line, and the simulation was used to confirm whether the product production process and production output volume can meet the target output. This study pointed out that the production line's capacity in one change in a single day differed from the actual production; there was a 12% error in the quantity. System simulation can not only perform production simulation for production lines but can also be used in companies that need to build new factories. The FlexSim simulation model was used to conduct a detailed analysis of the original layout of the factory [13; 14].