A 10-minute walk beyond Oksan Seowon up the valley road will bring you to Dongnakdang, a beautiful collection of well-preserved buildings, constructed in 1515 and expanded in 1532 as the residence of Yi Eon-jeok after he left government service. The walled compound is partly occupied by descendants of Master Yi himself and sits scenically next to a stream, though it was empty when we last visited. You can walk down the steps to the river, cross the stepping stones, and hike into the hills.
If you want to reach Dongnakdang first, take the 203 bus from Gyeongju to its final stop; then you can walk down the road to Oksan Seowon.