The calculated distance (air line) between Yonggang-ŭp and Hamhŭng is approximately 135 miles respectively 217 kilometers.
By car or train, the actual journey to Hamhŭng is certainly longer, as only the direct route (as the crow flies) between Yonggang-ŭp and Hamhŭng has been calculated here.
Air line (approximately)
217 kilometers
117 nautical miles