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
오존화는 대기 중의 오존 농도를 증가시키는 과정입니다.ozonhwa-neun daegi jung-ui ozon nongdo-reul jeungga-sikineun gwajeong-imnida.Ozonization is the process of increasing the concentration of ozone in the atmosphere.