① Both Consular Legalization(Notarization) and Apostille is the method to globally authenticate the domestic document of one country.
<aside> 💡
Whether you have to get Apostille/Korean Consular legalization depends on your nationality—if it is not joined in OECD, you have to get one of them.
</aside>
<aside> 💡
Which method to choose - it depends on the country where your home university is located in. Each country uses different way to authenticate their own document.
If the country is the party to the Hague convention(1961) and have the Apostille system, you can use apostille to authenticate your COE. If the country is not the party to the Hague convention, you should visit Korean Consular and get the notarization.
</aside>
② So these are the steps for your understanding:
STEP 1) If your home country is not in OECD
▶ You have to get your enrollment document apostilled or consular-legalized.
STEP 2) If your home university’s country is in Hague Convention
▶ You can get your enrollment document apostilled
(Countries which are able to use 'Apostille' does not provide 'Consular Legalization' anymore, as the Korean Embassy in Bern said.)
Signed Certificate of your university won't be sufficient. Please google "How to get apostille in (Country name)".
ex) https://schmidt-export.com/consular-legalization-and-apostille/apostille-switzerland