The calculated distance (air line) between Hwawŏn and Cheongsong gun is approximately 54 miles respectively 86 kilometers.
By car or train, the actual journey to Cheongsong gun is certainly longer, as only the direct route (as the crow flies) between Hwawŏn and Cheongsong gun has been calculated here.
Air line (approximately)
86 kilometers
47 nautical miles