The calculated distance (air line) between Haeju and Pyŏksŏng-ŭp is approximately 9 miles respectively 14 kilometers.
By car or train, the actual journey to Pyŏksŏng-ŭp is certainly longer, as only the direct route (as the crow flies) between Haeju and Pyŏksŏng-ŭp has been calculated here.
Air line (approximately)
14 kilometers
7 nautical miles