## 6 Conclusions  
This paper proposes improvement measures for reducing booming noise generated by the tailgate of an electric SUV by altering its related dynamic characteristics. Through a comprehensive analysis of results from road tests, ODS analysis, modal analysis, and otherexperimental findings, the mechanism of a tailgate's noise generation, including rigid and deformation behaviors in the fore-aft direction, was identified. Additionally, to investigate approaches for reducing booming noise, a simplified finite-element analysis model of the tailgate was established and validated through experimental results. Our key findings and contributions are summarized as follows:  
1. The impact of major design factors closely related to the booming noise of the tailgate was compared and analyzed. These factors, listed in order of sensitivity, include the stiffness of the guide bumper, the Young's modulus of the tailgate outer panel, and the Young's modulus of the vulnerable section of the inner panel. An improvement effect was confirmed by securing stiffness through structural changes in the inner panel to increase the Young's modulus of the vulnerable section.
2. A quantitative evaluation of the extent of improvement in tailgate behavior related to booming noise, under conditions similar to general driving situations, was conducted via random analysis following certified methods. These results showed a 13.8% reduction in the maximum deformation of the tailgate when subjected to road force inputs, achieved through structural changes in the inner panel.
3. Instead of using additional elements such as sound absorbers to address tailgate booming noise, effective improvement measures were proposed based on the results of our analysis of significant parameters related to the system.
4. If the model developed in this study is utilized during the tailgate design phase, we can reduce the time and costs of problem-solving and allow for proactive responses to mitigate booming noise.  
Conceptualization, J.C. and K.K.; methodology, J.C., D.K. and J.L.; experiment, D.K., J.L., M.C. and M.K.; investigation, D.K. and J.L.; modeling, D.K., S.J., M.C. and H.L.; validation, D.K., S.J. and K.K.; improvement evaluation, D.K., S.J., K.K., M.C., H.L. and M.K.; writing--original draft preparation, D.K.; writing--review and editing, M.C. and J.C.; supervision, J.C.; project administration, J.C.; funding acquisition, J.C. All authors have read and agreed to the published version of the manuscript. This work was supported by Hyundai Motor Co., Ltd. and sponsored by the National Research Foundation of Korea (NRF) through a grant from the Korean Government (MEST) (NRF-2021R1A2C2007979) and the Korea Institute for Advancement of Technology (KIAT) grant from the Korea Government (MOTIE) (P0012769, HRD Program for Industrial Innovation). Not applicable. Not applicable. Not applicable. Data Availability Statement: Data are contained within the article.  
[PERSON], [PERSON], [PERSON] and [PERSON] was employed by the company Hyundai Motor Company. 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.