The calculated distance (air line) between Hŭngnam and Chaeryŏng-ŭp is approximately 147 miles respectively 237 kilometers.
By car or train, the actual journey to Chaeryŏng-ŭp is certainly longer, as only the direct route (as the crow flies) between Hŭngnam and Chaeryŏng-ŭp has been calculated here.
Air line (approximately)
237 kilometers
128 nautical miles