Subway Cards

I am new to Busan and just switched to the subway cards (as compared to tickets).

The following website (http://www.subway.busan.kr/english/02/01_01.php) states that a roundtrip ticket for an adult with a subway "cards ticket" is 1,170 won.  However, I believe I was charged 990 won each way.  Am I not understanding the website correctly, is it mistaken, or am I supposed to do something different (than simply swipe my card) for roundtrip rides?

Thanks in advance!

this is my guess and i'm

this is my guess and i'm pretty sure its accurate...i'm thinking that the return trip has to be within a three hour window in order for the entire trip to be considered round trip.  otherwise, it's going to be two one way trips that are charged to your card. 

You get a free ride if you

You get a free ride if you get another bus within 30 minutes of getting off the bus you started on. You must 'beep' your card on the way out. If you transfer from the subway to a bus or the other way around you are changed a small fee (200won?) that 1170 amount might be the charge for a subway ride longer than 10 stops.

hmm not sure

Everytime I take the subway with my card I get charged 990won, I believe there is no such thing as round trip fare, however if you transfer to another subway or to a bus within 30 minutes from your last ride it's free or it's something like 200won. If you go far on the subway line you also might get charged a bit more, like 180won or something extra.

You can also purchase independently full-day tickets at a ticket vending machine for something around 3000won. But I'm pretty sure there is no round-trip fare when you use your T-card or whichever name you call it.