The calculated distance (air line) between Hwangju-ŭp and Namp’o is approximately 20 miles respectively 33 kilometers.
By car or train, the actual journey to Namp’o is certainly longer, as only the direct route (as the crow flies) between Hwangju-ŭp and Namp’o has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles