The calculated distance (air line) between Sŭngho 1-tong and Sunan is approximately 21 miles respectively 34 kilometers.
By car or train, the actual journey to Sunan is certainly longer, as only the direct route (as the crow flies) between Sŭngho 1-tong and Sunan has been calculated here.
Air line (approximately)
34 kilometers
18 nautical miles