Abstract: Control means is provided, in which the whole of the phase difference of a power waveform of each phase is matched to a value dividing a cycle of the power waveform into n-equal portions, and at the same time, the whole of the power value of each phase is controlled to be identical, so that the power conversion unit having a n-alternating current output (n is an integer numeral serving as n≧2) connected to the direct current power source and smoothing means provided between the direct current power source and the power conversion unit are made small in capacity.

Abstract: A work management system has a work management apparatus and a plurality of user terminals connected by a network. The work management apparatus stores employee information on employees and work management information for setting work contents of the employees, generates working schedule information indicating working schedules of the employees based on the employee information and the work management information, and sends the generated employee and management information to the user terminals through the network. The user terminals receives and displays the working schedule information.

Abstract: A method for manufacturing an optical information medium has a step of bending at least one of a first board and a second board having a center hole, a step of applying a radiation-curing resin onto the bent board in a doughnut form while the bent board is rotated, and a step of lapping the other board on the bent board and rotating the paired boards integrally.