The calculated distance (air line) between Chaeryŏng-ŭp and Koksan-ŭp is approximately 63 miles respectively 101 kilometers.
By car or train, the actual journey to Koksan-ŭp is certainly longer, as only the direct route (as the crow flies) between Chaeryŏng-ŭp and Koksan-ŭp has been calculated here.
Air line (approximately)
101 kilometers
54 nautical miles