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
편광기를 사용하여 빛의 방향을 조절할 수 있습니다.pyeonggwanggireul sayonghayeo bichiui banghyang-eul jojeolhal su issseubnida.You can control the direction of light using a polarizer.