## 6 Conclusions and Future Work
### Limitations and Future Works  
In this study, a quantitative evaluation index for assessing the psychological stability of following drivers in truck platooning situations was developed using a driving simulator, and experiments were conducted to analyze the effect of the see-through functionality on the psychological stability of drivers. However, this study had several limitations.  
First, owing to temporal and logistical constraints, only 20 participants could be recruited. Consequently, the representativeness of the experimental results may be limited. Since the outcomes may vary depending on participant characteristics such as age and gender, a sufficient sample size is required to ensure the generality and transferability of the findings. Future research should address this limitation by replicating the experiment with a larger sample to improve the reliability and external validity of the findings.  
Second, to prevent variations in the experimental results caused by factors unrelated to the purpose of the experiment, experimental conditions, such as vehicle speed, number of platooning vehicles, and position of the experimental vehicle within the platoon, were fixed during the simulator-based experiments. However, because truck platooning occurs under diverse conditions in real traffic environments, future studies should enhance the reliability of the findings by conducting experiments under diverse scenarios and conditions.  
Finally, this study was conducted in a driving simulator environment due to challenges related to experimental control, safety concerns, and cost, rather than under real-road conditions. While the simulator provides a safe and repeatable setting for testing, it has inherent limitations in replicating the full realism of real-road environments. As a result, the experiments may not fully capture edge cases or complex interactions that can occur in actual road conditions. To reduce these uncertainties and to validate and complement the simulation results, future studies should incorporate real-road experiments, thereby enhancing the ecological validity and applicability of the findings.  
Conceptualization, H.C., Y.K., S.O. and I.Y.; methodology, H.C. and Y.K.; validation, H.C. and Y.K.; formal analysis, H.C. and Y.K.; investigation, S.O. and I.Y.; resources, S.O. and I.Y.; writing--original draft preparation, H.C.; writing--review and editing, Y.K.; visualization, H.C. and Y.K.; supervision, S.O. and I.Y.; project administration, S.O. and I.Y.; funding acquisition, I.Y. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Korea Institute of Police Technology (KIPoT) grant funded by the Korea government (KNPA) (No. 092021C29S01000, Development of Traffic Congestion Management System for Urban Network).  
Not applicable.  
The datasets generated during the present study are available from the author, [PERSON] (e-mail: [EMAIL_ADDRESS]), upon request.  
Conflicts of Interest: Author [PERSON] was employed by the company Korea Expressway Corporation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.