The calculated distance (air line) between Onsŏng and Razdol’noye is approximately 104 miles respectively 167 kilometers.
By car or train, the actual journey to Razdol’noye is certainly longer, as only the direct route (as the crow flies) between Onsŏng and Razdol’noye has been calculated here.
Air line (approximately)
167 kilometers
90 nautical miles