Depending on your gate it can be a long hike to transit at ICN. Also it is likely OZ will dock in Terminal 1 and SQ depart Terminal 2 (should be on your ticket) which involves a train ride, throw in getting a boarding pass and security even 1.5 hrs is hurried. That said I have transited in the same terminal in 25min but it was a bit of a panic and I was greeted on exiting the plane to explain to me how to make the next flight in the minimum time.

If your ticket allows a no show on SQ you need to pay a penalty, a possible a fare difference and may be in for a long wait. Best to check the fare rules that apply to your booking class.