1. If you have valid driving license of India then you need not have Intl Driving License of India for getting Korea Driving license.

2. Contact Mr. Choi on Mobile No.: 010-3295- 6668. He is approved agent by Indian embassy. He charge about 15000 ~ 25000 KW for co-ordinating the document attestation.

3. He will ask you to send him your India driving license and passport copy along with original license. After getting attestation of copies he will send you all documents including original by courier.

4. As you are in Seoul then activity of point 3 above you can do on your own. It is just less than 30 minutes job at Indian embassy. In this case you can speak to Mr. Das or ms. Jung at embassy on 02-7984-257/ 268 ext. 118 to get all details.

5. Once you get your documents attested just visit to your nearest Koran Driving License Office (in India we call it as RTO). There you will get your Korean Driving License on same day (in my case it happened less than 1.5 hrs at Ulsan). Note that your Indian driving license will be retained by them which you can collect back in future by showing your flight ticket and passport. Then you need not have to return your Indian license any more.

6. Getting adjusted to left hand drive will take less than a week if you drove car earlier.

7. Helpful Video:

7. If you don't have valid driving license of India, you are needed to apply and go through the procedure like a korean citizen. 

OBTAINING a Korean License if you don't want to surrender your driver's license. The procedure is the same for both foreign residents and Korean nationals.
Requirements:
1. Apply in person at a Driver's License Agency (proxy applications are accepted under certain conditions).
2. You must be 18 years of age or over
3. Bring your Alien Registration Card (ARC). Those people who are legal residents but who are not issued an ARC must bring a record of their entries/exits.
4. Bring your Passport
5. Bring 3 photos (3cm x 4cm)
6. You will have to take a written test and driving tests, as well a physical test and safety course.
a. Written Test - about 40 or so questions - is available in English, Chinese, French, German, and Japanese. The DLA's have written materials available to help you prepare. The written test costs about W23,000, including the cost of the physical
b. Driving Tests - course driving and real driving - may be required.
c. Safety class takes about 3 hours (depends on where you live if there is one available in English or not) and costs W12,000.
FEES:
Physical exam W5,000
Written test W6,000
License processing fee W10,000 for acknowledged country and W16,000 unacknowledged country
More details on the DLA website
 
DURATION: Korean driver's licenses are valid for 7 years, except for those 65 or older who must renew every 5 years. 
ADDRESS CHANGE: Whenever you change your address, you must take your driver’s license to the gu office so that the change can be recorded on it as well as on your alien registration card. 

TEST SITES: English (or other languages) forms and/or translation are not available at all sites. You can contact 02-1577-1129 to confirm whether your local DLA office  has English or other languages (Cambodian, Chinese, Indonesian, Japanese, Mongol,, Russian, Tagalog, Thai and  Vietnamese). If that doesn't work, contact 02-1330 (the KTO help line and they may be able to identify where there may be English-speaking staff or possibly even provide some basic/limited translation. 
Information in English about Written and Driving Exams on the DLA website.

DRIVER'S LICENSE AGENCY 
Website  is in English, Chinese and Japanese available 
Main Office: Switchboard: (02)1577-1120 (recording in Korean - no English speakers)
E-mail: helpdesk@npa.go.kr (if no answer, you may want to follow-up by contacting 02-1330)
Address: 438 Sangam-dong, Mapo-gu, Seoul

Source :  http://www.korea4expats.com/article-driving-licences-korea.html

Here is the 250 cc two wheeler driving license test video in Korea.