Several large-scale accelerator facilities are operational or under construction in Korea, such as the 3rd Generation Synchrotron Light Source (PLS-II) and the X-ray Free Electron Laser (PAL-XFEL) in Pohang, the Korea Multi-purpose Accelerator Complex (KOMAC) in Gyeongju, the Rare Isotope Accelerator complex for ON-line experiments (RAON) in Daejeon, and the SNUH Gijang Cancer Center of Heavy Ion Therapy and Study (SGCC-HITS). Plus, a new 4th Generation Storage Ring (4GSR) is being constructed in Ochang. By using advanced beam physics models and simulation tools, cutting-edge beam diagnostics, and sophisticated beam manipulation/acceleration techniques, our research group contributes to the design, development, optimization, and improvement of those modern accelerators. Furthermore, we investigate transformational technologies for the next-generation high-intensity accelerators such as for the International Fusion Materials Irradiation Facility (IFMIF), Accelerator Driven System (ADS), and Heavy Ion Fusion (HIF). Applications of the accelerators to cancer therapy (e.g. FLASH), new materials research/drug discovery, and laboratory astrophysics will also be actively pursued.