This is regarding what is “Public Service Personnel”, which Heenim will be serving as. 

This is what i gather from Baidu Bar. 

“Public Service Personnel” is one who could work as deliveryman, selling of tickets…etc. The working place could be at Train stations or anyway. As they are celebrities, they may put on cap and mask when they work. And their working hours are fixed, knocking off at 6pm KST.(Timing wise i am not very clear, as i am not clear about the military systems. Every country differ.) Below is a picture of a Korean male celebrity. This is what he does as a Public Service Personnel. 

Credits:

Info from 金希澈吧

Shared by sillyjune of heechulfacts