Hi All,
All the writing is supposedly coming from the pretty lady with the megaphone and she's saying
You there lady with the loud voice ~ (I tend to translate more liberally so that the target audience gets the idea rather than translate literally)
You there gentleman holding the puppy ~
You there students pretending to be asleep ~
You there sir taking up the (whole row of) seats ~
Please think about other people a little.
?Hand phones on vibrate for others on the subway?/Phone calls quiet quietly/Group talks in a hushed whisper (literally whisper whisper)
Fold newspaper and read/Sit with your legs in/Give up seats for the elderly, handicapped, or pregnant women
Not sure about the bottom...something like
If [we] do this together, [we'll have] pleasant trains of etiquette
Done together by [This ad sponsdered by?] 5678 Seoul City Rail and Yahoo!
Regards,
Daideqi (Tae To'k-ki)
There's much more implied in Korean than in English, particularly in zippy 공익 (public service) campaign posters like this.