According to the KE website here are the details about the lounge:
* Location: North side of 3th floor of Passenger Terminal Building
* Operated by : Korean Air
* Open hour: 07:30 ~ 16:30
* Facilities
- FR/CLS : 10 seats , PR/CLS : 56 seats
- Beverage , light snack , soup
- Local /Korean /English newspapers and magazines
- TV , business space (internet, fax, printer)
- Toilet , Public Phone
- Free internet access
I have had issues accessing a KE lounge (in MNL) when not flying KE, but that was 18 months ago and things may be better now. This one is KE operated so you should have access, assuming you're there during the hours it is open.