Since patents and the like must be filed and registered in each country except a few communities, such as EU, in order to get a patent in Korea, 1) you must submit a patent application directly to Korea or 2) indirectly submit under the Paris Convention or the PCT with a priority within one year after the provisional or non-provisional application in your country (in the PCT case, it is possible to entry the national phase in Korea within 31 months from the first filing date).
As the Korean IP System, especially an electronic filing system of the Korean Intellectual Property Office (KIPO), is well equipped, it is possible to file an application etc. at any time, 24 hours a day, 365 days, and when accelerated examination is requested, you can be granted a patent within 3~6 months. If you need more detailed information with respect to the accelerated examination request, please click the KIPO's Accelerated Examination. If you submit the Request of Accelerated Examination with a Prior Art Search Report and a Statement for the reason, you can generally receive a notification of decision for accelerated examination.
A patent registered firstly in Korea can provide the basis for filing with other countries. By using the Patent Prosecution Highway (PPH) pilot program, it is possible to early register with the other countries which share the examination results of Korea. In this case, you can save money and time for getting patents in the other countries. The KIPO has been designated as an International Search Authority (ISA), and it is well-known fact that the KIPO has widely been used as the ISA of PCT application in other countries as well as in Korea due to the lower search cost. If you need more detailed information with respect to the PPH, please click the KIPO's Patent Prosecution Highway.