The calculated distance (air line) between Sinsang-ni and Hongwŏn is approximately 39 miles respectively 63 kilometers.
By car or train, the actual journey to Hongwŏn is certainly longer, as only the direct route (as the crow flies) between Sinsang-ni and Hongwŏn has been calculated here.
Air line (approximately)
63 kilometers
34 nautical miles