The calculated distance (air line) between Ganghwa-gun and Gwangmyeong is approximately 28 miles respectively 45 kilometers.
By car or train, the actual journey to Gwangmyeong is certainly longer, as only the direct route (as the crow flies) between Ganghwa-gun and Gwangmyeong has been calculated here.
Air line (approximately)
45 kilometers
24 nautical miles