Visa Requirements for English Teachers and Cambodians

Hi,

I worked in Busan several years ago and at the time had to take a trip over to Japan to get a working Visa. Can anyone tell me what documents I need now to work in Busan? I would also like to know what the visa requirements are for Cambodians as I plan to travel with my daughter who was born in Cambodia and my Cambodian wife. Any info would be very much appreciated. Thank You in advance..