Abstract: Disclosure is a metal mold for forming a transparent-resin-sealed semiconductor element which, when the molding is removed from it with knock-out pins, will not rub the molding mirror surface of the light transmitting window of the resin package, thus permitting the removal of the molding with the molding mirror surface maintained as it is. In the metal mold for a transparent-resin-sealed semiconductor element which is formed by sealing a semiconductor photo-electric element mounted on a lead frame in a rectangular-parallelepiped-shaped transparent resin package having a light transmitting window on its front end, the cavity surface of the upper die (a cavity block) which corresponds to the light transmitting window has a draft angle .theta.

Abstract: In a slip frequency control system hitherto widely employed as a control system for an induction motor type electric rolling stock (in which a slip frequency is determined from a current deviation, an inverter frequency is calculated from the slip frequency and a motor rotation frequency, and the inverter frequency is multiplied by a predetermined correction factor to determine a modulation rate, thereby operating an inverter), a motor output torque decreases in a low speed region. It is difficult to make the correction for this decrease of torque by detecting the torque. In the present invention made considering that a torque curve and sin .phi. (.phi.: the internal impedance angle of a motor) obtained from the result of simulation resemble each other, the decrease of sin .phi. is regarded as being the decrease of torque and a voltage to frequency ratio is corrected so as to compensate for the decrease of sin .phi..