And straight from the hotel:Regarding your inquiry, you can take a bus #6015. It costs KRW 17,000 per person.
The bus stop is Euljiro 2ga(Pine Avenue).It takes 3-5 mins to hotel by walk.
And also you can take an AREX(Airport Railroad) and you can transfer line #2 at Hongik university.
Hotel is right in front of the Exit #12 of Euljiro 3 ga.