If you are currently considering working outside South Africa, especially in the teaching profession, your first step should be to apply for a Police Criminal Record (CRC) certificate. This is a very simple process, that requires you to go to your nearest Police Station, with your ID/passport, application form, and R59 per CRC certificate. It however on average can take 2 months and longer for the Criminal Records Deparement to process your request, hence it is recommended that you apply for this immediately, even if you are still unsure about traveling abroad, or whether you have work or not. Many countries, including Korea, require you to have this CRC before you can apply for a work permit, hence if you find a position, but do not have a CRC, you will have to wait an additional 2 months. It technically is possible to get your CRC slightly sooner if you request that your CRC application must be "rushed" however, you will need to give a very good reason in the form of a written letter to the head of the Head of the South African Criminal Record Centre for this to take place, and in most cases this will not be granted. It is also recommended to apply for more than 1 CRC if you are thinking of applying to multiple organizations. EPIK (English Program in Korea) for example require you to send the original CRC in to them during the initial application process. Which means, that you cannot apply for any other positions, unless you have more than one CRC. Information about how to apply for a CRC can be found here: http://www.saps.gov.za/_dynamicModules/internetSite/faqBuild.asp?myURL=272.
You do not have to go to the Criminal Record Centre in Pretoria in person, instead you can make use of courier services such as those offered by PostNet. This is very convenient, since they deliver and collect all the documents for you, it does however cost a bit more. For Korea, you also need to get your CRC (and qualifications) apostilled. This is free of charge, and can be done at a high court in your area. Alternatively, you can request that the PostNet courier take your CRC from the Criminal Record Centre directly to the high court in Pretoria. The apostille process can be completed within a hour.
The apostille certificate can be a confusing process, and I would recommend that you do your own research on this. In essence an apostille is the same as getting your photocopies notarized at a police station in South Africa (i.e., to certify that a photocopy is a real copy of the original document), it however is a little more official (a certificate of authenticity is attached to your photocopy), it is done at the courts (as supposed to the police office), and it conforms to international standards for notarization.