Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
이 구조물은 압축 응력을 받은 상태에서 설계되었습니다.i gujo-mul-eun apchuk eungnyeogeul bad-eun sangtaeeseo seolgyehaessseubnida.This structure was designed in a prestressed state.