The calculated distance (air line) between Helong and Sŭngjibaegam is approximately 90 miles respectively 145 kilometers.
By car or train, the actual journey to Sŭngjibaegam is certainly longer, as only the direct route (as the crow flies) between Helong and Sŭngjibaegam has been calculated here.
Air line (approximately)
145 kilometers
78 nautical miles