The calculated distance (air line) between Yonggang-ŭp and Songnim-ni is approximately 13 miles respectively 21 kilometers.
By car or train, the actual journey to Songnim-ni is certainly longer, as only the direct route (as the crow flies) between Yonggang-ŭp and Songnim-ni has been calculated here.
Air line (approximately)
21 kilometers
12 nautical miles