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
위상궤적은 시스템의 동작을 이해하는 데 중요하다.wisanggwaejeogeun siseutem-ui dongjag-eul ihaehaneun de jungyohada.The phase trajectory is important for understanding the operation of the system.