Hoam Faculty House, (~$100/night). The Hoam Faculty House is a guesthouse of Seoul National University. It is located in the heart of Seoul, making it easily accessible from the airport, train station, and major subway stations. The Hoam Faculty House is an ideal venue for IUTAM. 

Four Points by Sheraton Seoul, (~$100/night). Four Points by Sheraton Seoul is located about 10-15 minutes by car to Seoul National University, and it is a very convenient hotel with airport bus station in front of the hotel and subway station on Line 2.

Shilla Stay
This is one of the popular business hotels in Seoul (~$120/night).

There are several branches (Yeoksam branch and Samsung branch are close to the subway station of the 2nd line).

Glad Hotel
This is another business hotel at a lower rate (~$100/night).

GLAD Gangnam COEX Center is the most convenient one.

Grand Intercontinental Seoul Parnas
This is one of the popular upscale (5-star) hotels in Seoul (~$200/night).