It's a pity it's not a papaya, but it definitely isn't. Papayas are so much better and can be eaten both ripe and unripe. The famous Thai (actually it came from Laos) papaya salad is made from the unripe fruit.
Here are unripe papayas on a tree just outside my home. I'd steal one, but they are inside a police station's grounds.
When ripe, they do turn yellow, but do not have those white stripes in your photograph.
The Korean melon or chamoe which you have, while inexplicably popular in er, of all places, Korea, is one of the least interesting melons I've come across. We get them here, too. In fact, it was China which introduced them to Korea, largely because it seemed a good idea to dump the garbage on someone else. Allegedly.
