Both are ok.

Many merchants in South Korea support UnionPay. You can choose to swipe UnionPay when swiping your card. If the merchant only provides card swiping lines for international organizations, you can also swipe international organization lines.

If you pay with UnionPay, it will be converted into RMB and recorded in RMB according to the exchange rate provided by UnionPay. If the payment is from an international organization line, (because this card is a global payment card, it is not calculated according to the exchange rate of international organizations, and no exchange fee is charged). It will be automatically converted into RMB at the exchange rate of the CCB credit card on the day of entry and entered into the account. The exchange rates between the two are slightly different, but I can't say which one is more cost-effective. I feel the same after using it myself, because the exchange rate changes every day, and it takes several days to enter the account through the international organization route, and it is impossible to predict the exchange rate situation in the next few days, so It all depends on personal convenience, which one is more convenient for you to use.