# Underwater Excavation Records Using Underwater Acoustic Survey: A Case Study in South Korea
## 6 Conclusions  
In this study, we investigated various imaging methods during UEs with acoustic MGS equipment. Specifically, three acoustic MGS devices were used in the waters off Dangampo, Taean County; Nakwoldo Island, Yeonggwang County; and at the site of the Battle of Myeongnyang near Jindo Island from 2017 to 2019 to investigate the advantages and disadvantages of different survey imaging methods. At the Dangampo site, SS proved to be more efficient than SiSS and MBES for SRA imaging. At the Nakwoldo site, a series of SS images were combined into a full image covering the entire survey area, which was then used to produce a survey chart. At the Myeongnyang site, a reflector was installed on the seafloor at regular intervals for use as a reference point to increase the accuracy of the final mosaic image. We verified that a high-quality image of the survey site could be obtained using an SS, even in turbid underwater environments where measurements or photogrammetry are difficult to perform.  
The primary limitation to the generalization of our findings is that the MGS equipment testing was performed in areas where underwater relics were dispersed. Potential discoveries of ancient shipwcks may require additional preparatory measures for rapid and accurate surveying under conditions not conducive to photogrammetry. Given that the seafloor areas where relics are dispersed are generally extensive and flat, unlike ancient shipwcks sites that are narrow and three-dimensional, the methods presented in this study cannot be used without further adjustment. It is expected that various survey methods that are able to overcome adverse conditions will be developed in future research. Furthermore, we believe that the application of the SS methodology in conjunction with high-frequency geophysical exploration techniques will increase the reliability of investigations of buried underwater remains and relics.  
The proposed geophysical survey techniques for excavation research have been applied to various subjects in underwater archeological research, including ancient shipwcks [16], underwater remains, and relics, and the results of this study confirm their applicability. Furthermore, the future application of geophysical and sonar techniques during underwater excavation research will represent an effective approach for checking the progress of the excavation and exploration of relics. This study is the first to have researched the progress of underwater excavations in South Korea using this technology, and we will continue to collect relevant scientific data that may lead to improvements in underwater excavations through continuous research.  
Conceptualization, S.-B.K. and Y.-H.L.; methodology, J.-H.K.; software, S.-H.L.; validation, S.-B.K., Y.-H.L. and S.-H.L.; formal analysis, J.-H.K.; investigation, Y.-H.L. and S.-B.K.; resources, Y.-H.L.; data curation, J.-H.K.; writing--original draft preparation, Y.-H.L.; writing--review and editing, S.-B.K.; visualization, S.-H.L.; supervision, J.-H.K.; project administration, S.-B.K.; funding acquisition, Y.-H.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the academic research grants from Young-San University and the Korea National Research Institute of Maritime Cultural Heritage.