The standard voltage in South Korea is 220 volts and 60Hz.
South Korea uses two types of plugs, Plug Type C (Europlug) and Plug Type F (German Schuko). These types of plugs have two round pins that are placed 19mm apart from each other. The pins fit into two 4.0mm to 4.8mm round holes. These types of plugs and outlets are the same used in almost all of Europe except for a few countries.
Most electronics today, including laptops and camera battery chargers, have built in power transformers that can adapt to the local voltage. To check the voltage of your power supply, look on the power block or on the back label of your electrical item or plug.
If your electrical item or power cord does not have a built in power transformer, then you will need to use a power converter. These can be purchased or often borrowed from the hotel.
Unless you are coming from Europe (expect United Kingdom, Ireland, Cyprus or Malta) to Korea, you will need a simple adapter to plug in your electronics such as European Plug Adapter. Look for one that adapts your local connector to the German Schuko/Europlug Outlet.