The calculated distance (air line) between Pyŏksŏng-ŭp and Sariwŏn is approximately 34 miles respectively 54 kilometers.
By car or train, the actual journey to Sariwŏn is certainly longer, as only the direct route (as the crow flies) between Pyŏksŏng-ŭp and Sariwŏn has been calculated here.
Air line (approximately)
54 kilometers
29 nautical miles