Ok, You take the subway (Arex).
And take a lodgment to the nearby subway station.
You can go on a trip by subway Everyday.
GongDeok : HongDae, central and west side of Seoul, approach airport by subway
GeonGuk Univ. : East side of Seoul
YeongDeungPo-Gu Office: Mullaem art village, YeoEuiDo, HanGang park, west south of Seoul,
Seoul Natl. Univ of Education : GangNam
HanSung Univ. : HyeHwa (Marronnier Park & Many Theater), central of Seoul, north side of Seoul