This is the 89th most frequent Korean word.
기존
Existing; preexisting.
In this sentence, '기존' refers to the existing or current method being discussed, emphasizing something that is already established.
기존 방식으로 진행하면 시간이 오래 걸립니다.
If we proceed with the existing method, it will take a long time.
Here, '기존' describes 'customers', indicating those who are already established as clients.
회사는 기존 고객들을 위해 특별한 할인을 제공하고 있습니다.
The company is providing special discounts for existing customers.
In this context, '기존' modifies 'data', meaning that the data already exists and has been under consideration or analysis.