Person more than 55 years old and their unmarried children
If you or your parents are over 55 years old, you can purchase a South Korean government bond of US$300,000 to obtain a residence visa (F-2) for free economic activities. After 5 years, you or your parents can apply Korean Permanent Resident Visa (F-5). After having Permanent Resident Visa (F-5), you can apply Korean Citizenship.
This VISA can be applied to dependent family member including wife and unmarried children.