It is impossible to convert an international Driver's License to a Korean Driver's License.
It is impossible to convert any foreign License to an International Driver's License (in Korea).
    This should be done in the country the License has been issued. And it will only be possible if the foreign license is first converted to a Korean Driver's License. An International Driver's License is valid only one year.
     
  Acquiring a Korean Driver's License
    Same procedures for Korean applicants.
A Korean Driver's License is valid 9 years (since June 30, 2002).
   
Required Documents:
Proof of having passed all required tests:
Written test application, application fee of 5,000 won, certificate of alien registration, felt pen, and a score above 80 for 1st category license or a score above 70 for 2nd category license (Tests available in English, French, German, Japanese, and Chinese.)
Closed Course Driving Test application, application fee of 15,000 won, certificate of alien registration, felt pen, and a score above 80
Provisional Driver's License drivers must provide evidence of driving with an experienced driver (over one year of driving experience) for at least 10 hours before applying for the public road driving test
Public Road Driving Test application, application fee of 15,000 won, about a 3km. test course and a score above 70 (during validity of the Provisional Driver's License)
Passport or Certificate of Alien Registration
    (you must have lived in Korea for at least 6 months)
Three recent photos (3 x 4 cm.)
Application fee: 5,000 won
Physical examination fee: 5,000 won
    In the case of losing your license, you will need to go to any 24 Driver's License Examination Office or the license section of the National Police Administration with the following documents: Passport or Certificate of Alien Registration, two recent photos (3 x 4 cm), and the application fee for the reissuance of the license which is 7,000 won. You will get the license the same day.
       
  Converting your License to a Korean Driver's License
    (Not available for all countries and states, in case of U.S.)
There are 24 Driver's License Examination Offices in charge of license applications.
It usually takes 7 to 10 days to get a Korean Driver's License.
   
Required Documents:
Translated and notarized driver's license (verification statement) issued by your own country of origin or in your respective embassy) * If you don't have this, translation and notarization fees are to be paid. (A signature of a translator is required.)
Passport or Certificate of Alien Registration
Four recent photos (3 x 4 cm.)
Application fee: 5,000 won
Physical examination fee: 5,000 won