The calculated distance (air line) between Hŭngnam and Sŭngjibaegam is approximately 115 miles respectively 184 kilometers.
By car or train, the actual journey to Sŭngjibaegam is certainly longer, as only the direct route (as the crow flies) between Hŭngnam and Sŭngjibaegam has been calculated here.
Air line (approximately)
184 kilometers
99 nautical miles