## 4 Discussion and Conclusions  
Compaction is one of the most critical aspects of earthwork operations. The real-time compaction information can allow the construction manager to plan and execute the operation effectively. However, traditional QA/QC methods are still in practice, which do not provide real-time information and cannot assess the compaction quality throughout the construction site. Furthermore, these tests are time-consuming, labor-intensive, and based on the engineer's experience. Automation and information technology have recently been implemented in the construction industry to solve such problems; however, compaction and other heavy machinery operations require more mature efforts. This study set out to develop an intelligent compaction system to manage compaction operations efficiently and evaluate its effectiveness. The first part of the study discusses in detail the developed system consisting of three major components: system hardware, system software, and compaction measurement calculations. The second part investigates the developed system's performance by comparing it with the established traditional compaction quality control method. The findings of the linear regression analysis indicate a strong relationship between the CMV and in situ measurements, with the coefficient of determination greater than 0.85. The practical implementation was conducted on two real construction projects, which validated the effectiveness and feasibility of the developed system. Figure 11: Screenshot of the compaction strength information. Overall, this study confirms the previous efforts and provides additional detailed evidence for implementing the IC roller in the construction industry. Although this study has successfully demonstrated the potential of the developed system, it has several weaknesses. One limitation of this study is that the research results depend on the two specific site conditions and material types, which implies that a calibration area is always required for new site conditions. Another potential source of weakness in this study is that it investigates only non-plastic earthen material for the compaction layer. In terms of the direction of future research, further studies need to be carried out in different soil or aggregate types. The correlation of CMV with other non-destructive in situ compaction measurement techniques may also be studied. Non-linear models and more sophisticated regression analysis tools and techniques need to be employed in the future to study the above correlation. Conceptualization, S.L., A.S. and J.S. ; Data curation, S.L. and I.S.K. ; Formal analysis, A.S., I.S.K. and J.S. ; Funding acquisition, J.S. ; Methodology, A.S. and I.S.K. ; Validation, S.L., A.S. and I.S.K. ; Writing--original draft, S.L. ; Writing--review & editing, A.S. and J.S. All authors have read and agreed to the published version of the manuscript. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (No. NRF 2018R1A5A1025137) and the Ministry of Land, Infrastructure, and Transport (National Research for Smart Construction Technology, grant 22 SMIP-A158708-03). Not applicable. The authors declare no conflict of interest. The following abbreviations are used in this manuscript: