Watch out for anyone trying to sell International Driver’s License (IDL), because there is no such license that exists. What you are looking for is an International Driver’s Permit (IDP), which must accompany a valid Driver’s license so as to be legal. There are many sites that will help you, but most of them are unreasonably expensive.
It’s better to search the website of the organization within your home country, like the one in Canada called Canadian Automobile Association (CAA) and the one in US (AAA). The NRMA (motor club) in Australia cost about (US) $10 and allows you to drive anywhere. Its validity is for one year or until the Aussie license expires. It wouldn’t be difficult to find out the organizations in other countries. Next procedure is to download an application and mail it to them along with your two passport size photos and a photocopy of your DL, and (Ca) $13 (bank draft or credit card). This is cheaper than other website-based services that charge (US) $30. You can also exchange your US license to a Korean license, which can be done in Seoul as it is easier.
You can get Korean version of an International Driving Permit, if you have a Korean driving license and if you have been in Korea for more than three years. However, you might rent cars without any of these. All you need is a Major Credit Card, your driver’s license and passport and you are on your way, its one of the local rental operations. This even makes us ask if IDP is really required or are we just under the impression that it is necessary. Yet in many countries you can rent cars without being asked for any driver’s license.