The calculated distance (air line) between Pyŏksŏng-ŭp and Sinŭiju is approximately 155 miles respectively 249 kilometers.
By car or train, the actual journey to Sinŭiju is certainly longer, as only the direct route (as the crow flies) between Pyŏksŏng-ŭp and Sinŭiju has been calculated here.
Air line (approximately)
249 kilometers
134 nautical miles