The workshop venue is Korea Institute for Advanced Study, Building 1, Room 1503. You can show this address to the taxi driver:

동대문구 회기로 85, 카이스트 1호관
(Building 1 of KAIST, on the 85 Hoegi-ro, Dongdaemun-gu)

 If you take a taxi from the city center of Seoul to KIAS, it should cost around KRW 15,000. KIAS is inside the KAIST Seoul campus.

If the bus line 201 / 273 / 1226 / 3216 passes nearby your place, you can also come by bus. Google maps works well for public transportation.

If you take a subway ride, the nearest subway stations are Korea University station (Line 6) and Cheongnyang-ri station (Line 1). It will take 13 min. (20 min.) walk from the stations, respectively.