The calculated distance (air line) between Cheongsong gun and Pyeongtaek is approximately 116 miles respectively 186 kilometers.
By car or train, the actual journey to Pyeongtaek is certainly longer, as only the direct route (as the crow flies) between Cheongsong gun and Pyeongtaek has been calculated here.
Air line (approximately)
186 kilometers
100 nautical miles