Bangkok: the capital of Thailand. Middle area almost at the bottom of the mainland.
Koh Chang: look at the bottom right side of the map (cream colored portion). You'll see TRAT and then the island spelled KO CHANG on this map.
Chiang Mai: right by the word Northern on this map, just look to the left of the word.
Back to Bangkok and then home to S. Korea. (6 hour flight from S. Korea to Thailand)