Your Android apps and Iphone apps are accessible from people all around the world. As you know, English is the main language worldwide, but all smartphone users are able to understand English very well.
Korean itself have 49 million people. What a large market. It is double than Malaysia.
As you know, with that large market.. you can make a lot of money by ensure that your Android apps and Iphone apps are available in their own language. Such as, Korean version Android apps.
Moreover, it is really cheap to have a translator at the moment. Cheap yet professional English Korean translator is available on the internet. Just go to Google then type your desired keywords will give you a full list of Korean translator.
Why it is cheap? Because many of English Korean translator now have their own business website. So you are dealing directly with the translator. No middle man!