When applying for a work visa to come to South Korea, there is a possibility you will be requested to submit drug test results, depending on which visa you are applying for.
For example, E2-visa holders need to undergo a drug test within 3 months of arriving in South Korea. If you test positive for the test, it is possible that your work contract will be terminated and you will have to leave the country.
Drug test is usually done by testing hair or urine of the suspect. Recently, police also started examining suspect’s fingernails, leg hair, eyebrows, or even pubic hair, because users or dealers try to hide their crime by shaving or dying their hair.