Abstract: The present invention permits mounting and optimization of a hierarchically necessary number of units corresponding to the scale of input/output subsystems. An input/output subsystem is organized by dividing it into a basic portion including power units and an expanded portion including one or more input/output units. Each of the input/output subsystems has a plurality of built-in magnetic disk modules. The enclosure of a subsystem are composed of a basic enclosure mounting thereon power units and a prescribed number of input/output units forming a basic portion, and an expanded enclosure mounting thereon remaining input/output units other than those mounted on the basic enclosure. The power unit automatically recognizes the mounting status of input/output units, and ensures a necessary power supply capacity.

Abstract: A heat insulation structure for a liquefied gas storage tank is disclosed which comprises a plurality of heat insulation sandwich structure units attached to the outer tank shell. Each sandwich structure unit comprises a plurality of core members or ribs arrayed in spaced apart relation and sandwiched by a top and bottom plate members, and insulating materials filled into the spaces defined by the core members and the top and bottom plate members, and each core member or rib comprises a pair of plywood sheet members spaced apart from each other by a predetermined distance by spacers, and insulating materials filled into the space or spaces defined by the sheet members and spacers. The above construction not only gives much strength to the heat insulation structure in addition to the improved ability to interrupt heat conduction, but also reduces the fabrication cost.