The doctors who are willing to visit South Korea for a short-stay period should apply for a Single entry visa at Korean embassies or consulates abroad. This visa permits a stay for not more than 90 days and the visa fee would be US$40. The Visa applicants are required to submit application forms, passport, a recent passport-size color photograph, copy of the applicant's most recent monthly bank statement showing proof of sufficient funds, personal invitation letter for the conference and other relevant documents as determined by their status of stay. It takes 5 working days for issuing a visa and is valid for 3 months from the date of issue. You can apply online and courier the documents to the consulate.

For more information, please click the below mentioned links

http://www.mofa.go.kr/ENG/visa/application/index.jsp?menu=m_40_10

http://www.learn4good.com/travel/south_korean_visas_requirements.htm