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
마찰계는 재료의 마찰 특성을 측정하는 데 사용됩니다.Machal-gye-neun jaeryo-ui machal teukseong-eul cheugjeonghaneun de sayongdoemnida.A tribometer is used to measure the friction properties of materials.