The calculated distance (air line) between Yongsan-dong and Cheongju-si is approximately 69 miles respectively 110 kilometers.
By car or train, the actual journey to Cheongju-si is certainly longer, as only the direct route (as the crow flies) between Yongsan-dong and Cheongju-si has been calculated here.
Air line (approximately)
110 kilometers
60 nautical miles