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
마찰공학은 마찰과 관련된 현상을 연구하는 학문입니다.Machal-gonghak-eun machal-gwa gwanryeon-doen hyeonsang-eul yeonguhaneun hakmun-imnida.Tribology is the study of phenomena related to friction.