Went on a trip to Korea last week. In terms of payment, Korean shops are generally well equipped with credit facilities and large sums of cash is not required.
For my trip, I carried SGD$300 for 4 days and it was sufficient to cover my food and shopping. I did a comparison with my friends exchange rates who changed their Won at various locations:
Comparison of exchange rates
Me ( I changed at The Arcade at Raffles Place) : 815 -817 Won / SGD.
Chinatown : 816 Won / SGD.
Neighbourhood: 815 Won / SGD.
Airport: 737 Won / SGD. ( Not sure if my friend made a mistake, but in any case as previously mentioned from my post on currency exchange tips, try not to change at the airport!)
I also swiped my card to buy my train pass. The bank charged me at a rate of 805.3 Won / SGD.
For where is the best place to change money in Singapore, read here
Tip: The price of convenience
Travelling somewhere? Remember to check out my post for travel tips for the young adult! Hope this was useful for you!