My parents in South Korea need money to buy a place to live, and I want to send my savings to help them out financially. I am concerend whether I have to pay tax to INS for the money I am sending from the US.
Thanks!

There is NO transfer tax on the part of the United States, though South Korea may have one.

The INS will only question the source on the money; if you have been paying taxes on the savings, the source will be obvious.