* -다가 = describes a case where something unintended happens (or the doer changes his mind to do something else) while doing another thing. * -고 나서 = 나서(나다) means "coming out of (something)", so the phrase means after doing/finishing something. * -면서 = "(at the same time) while doing something". -며 is also used in the same meaning. * -는 동안(에) = "during the time something is happening". Similar to -면서, but emphasizes "within the time it takes to do the something". Examples: - 엎드려 책을 보다가 잠이 들어 버렸다 = I fell asleep while reading a book lying on my belly. - 나는 숙제를 다 하고 나서 티브이를 보았다 = I watched TV after finishing my homework. - 동생은 눈을 껌벅이면서 [껌벅이며] 울었다 = My little brother cried blinking his eyes. - 내가 숙제을 하는 동안(에) 동생은 옆에서 놀았다 = While I did my homework, my little brother played by my side. - 방을 치우다가 없어졌던 책을 찾았다. = I found a missing book while cleaning up my room. - 방을 치우고 나서 새 책상을 들여놓았다 = I put in the new desk after cleaning up my room. - 방을 치우면서 먼지를 많이 마셨다 = I breathed in a lot of dust while cleaning up my room. - 방을 치우는 동안 밖에는 비가 내렸다 = It rained outside while I cleaned up my room [throughout the time I cleaned up my room].