SQ ICN-SFO then transfer to AC
Hello
I am leaving ICN via SFO on SQ then transfer to AC to go to YYZ.
I hope to use the SQ lounge, it should not be a problem as I am arriving on SQ J.
SQ arrives in INternational terminal while AC leaves Terminal 3. Will I need to go in and out? Can I go directly to lounge then go to AC gate? How many security checkpoints?