-아/어 내다 — To achieve, To manage to do, To pull off, To finish through effort

This expression is used to indicate that the subject was able to complete some task after experiencing some difficulty or was finally able to finish the task alone. Thus it is used together with both verbs related to carrying out or completing tasks and verbs that indicate the surmounting of some obstacle. For this reason, it is not used with retention verbs such as 놓다, 두다 and 가지다.

Details

When used together with verbs such as ‘알다’, ‘찾다’, ‘하다’, ‘밝히다’ this expression is written together as 알아내다, 찾아내다, 해내다 and 밝혀내다 without a space.

여기저기 수소문하여 초등학교 동창의 연락처를 알아냈다.

경찰은 사건을 해결할 수 있는 결정적인 증거를 찾아냈다.

배우 류승호 씨는 위험한 액션 연기를 대역 배우 없이 해냈다.

수소문하다: to ask around (for information)
대역 배우: stunt double

가: 우리 회사 연구 팀이 이번에 개발한 제품이 무척 잘 팔린다면서요? 나: 네, 기존 제품에 없는 기능도 많아서 특허도 5개나 땄대요. 그래서인지 경쟁 회사 제품보다 열 배 이상 더 잘 팔린다고 하더라고요. 가: 정말 대단하군요. 강세호 팀장이 그 오랜 세월 묵묵히 일하더니 그런 좋은 성과를 이루어 냈군요. 나: 그런데 강 팀장님 말로는 이렇게 많은 특허를 딸 수 있었던 데에는 아내의 힘이 컸다고 하더라고요. 아내분이 여러 가지 아이디어를 많이 생각해 낸 덕분이래요.

A: Is it true that the product our company research team developed is really selling like crazy? B: Yes, I heard that it has a lot of functions that aren't on previous products, and we were able to obtain 5 new patents. Perhaps that's the reason why they say our product is outselling that of the competition by a factor of 10. A: That's really amazing. I suppose our team chief Kang Seho was able to realize such good results after plodding away so quietly and diligently at his job for all this time. B: But according to Kang himself, his wife was an important factor in their being able to get so many patents. He said it was thanks to his wife’s coming up with a lot of ideas.