Abstract: In a semiconductor module, at least one snubber circuit module is attachable/detachable to/from an interior communicated with a snubber-circuit-connecting opening; a plurality of snubber-circuit electrodes for electrically connecting with the at least one snubber circuit module are joined with a circuit pattern; the plurality of snubber-circuit electrodes are disposed in the interior of the snubber-circuit-connecting opening; in a state that the snubber circuit module is attached in the interior of the snubber-circuit-connecting opening, the snubber circuit module does not stick out from an outer surface of an outer enclosure member, the plurality of snubber-circuit electrodes are in surface-contact with electrodes in the side of the snubber circuit module, respectively; and the snubber-circuit-connecting opening and the interior are not overlapped with the at least one semiconductor element in a planar view.

Abstract: There is provided a method and apparatus for upwardly excavating a shaft through destructible underground rock. The cutting operation is carried out by full face boring without relying on blasting. An operation for supporting the shaft side wall is carried out by means of frame segments loosely following the advance of the bit. The cutting operation and supporting operation are independent from one another. The diameter of the bit is contracted after the cutting operation to allow the bit to be lowered down through the frame segments.

Abstract: There is provided a method and apparatus for supporting the wall of an upwardly excavated shaft. Cylindrical support frames which are successively thrust up through the shaft are respectively composed of several arcuate members and one or more disjointing members. A plurality of top supporting plates are provided on the top of the series of the cylindrical frames and are designed to fall inwardly toward the center of the shaft after the excavation of the shaft is terminated, thus constructing an umbrella like device for supporting the roof of the shaft.