You must go to the nearest Korean Consulate to apply for your visa and arrange for your consul's interview.

Your visa application will need your employer information such as name, address…etc. Please remember that your address in Korea is same as your employer’s address and contact number is your employer’s phone number.
You must visit nearest Korean embassy or consulate along with items as listed below

1.        Application Form
2.        Notice of Employment Appointment
3.        One copy of signed contract
4.        Your passport
5.        Two passport size photo
6.        Sealed Transcript
7.        Visa fee (it may cost you US$60, it may vary depends on country where you apply)

It is applicant’s decision to choose entry type of Visa. Single entry may cost you less than multiple entry, but KorVia Consulting recommend you to apply for a multiple entry for you overseas vacation during employment.
Note : Single entry visa holder should be careful to travel overseas. Your single entry visa will be cancelled automatically as soon as you are out of Korea.  (you visa can be changed during your employment period, but it may cost you time and money for extra.)
Visa application may takes several days depends on Embassy or Consulate you have been. Visa will be stamped on your passport