Yangjaecheon. Yangjaecheon (Korean:???????????) is a stream that flows through the city of Seoul, South Korea. It runs through Gangnam, which is part of the southern half of the city. Yangjaecheon is a greenway stretching five and a half kilometres from Gwanaksan in Gyeonggi through the Seocho, Gangnam, and Songpa districts until it feeds into the Tancheon.