Two patterns hold the real lines here. The doubled 을락 말락 means right on the brink, neither quite happening nor not: about to rain, her face almost surfacing in memory and then slipping away, half falling asleep. And 오르락 내리락 is the fixed up-and-down phrase in the line about life always going up and down. The remaining lines are sound words, where the same syllable is part of a rustling or whooshing noise.