The calculated distance (air line) between Komusan Il-tong and Onsŏng is approximately 60 miles respectively 97 kilometers.
By car or train, the actual journey to Onsŏng is certainly longer, as only the direct route (as the crow flies) between Komusan Il-tong and Onsŏng has been calculated here.
Air line (approximately)
97 kilometers
53 nautical miles