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
반사계를 사용하여 빛의 반사를 측정할 수 있습니다.bansagye-reul sayonghayeo bich-ui bansareul cheugjeonghal su itsseumnida.You can measure the reflection of light using a reflectometer.