The calculated distance (air line) between Yongsan-dong and Pyeongtaek is approximately 38 miles respectively 62 kilometers.
By car or train, the actual journey to Pyeongtaek is certainly longer, as only the direct route (as the crow flies) between Yongsan-dong and Pyeongtaek has been calculated here.
Air line (approximately)
62 kilometers
33 nautical miles