How will checked in bag will be transferred from one airline to another at Beijing Capital Airport?

I’m arriving from ULN ( flight no. OM223 ) with onward flight to SIN ( SQ807 ) on same day. I have checked in bag from ULN. How and where can I get my checked in bag in PEK airport to transfer to my next flight without going thru immigration? It will be my first time to use a transfer desk. Please let me know.