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
태환은 에너지를 다른 형태로 바꾸는 과정입니다.Taehwan-eun eoneojireul dareun hyeongtaero bakkuneun gwajeong-imnida.Conversion is the process of changing energy into another form.