A semiconductor memory device includes transistors that supply a higher write potential and a lower write potential to a sense amplifier, respectively, an overdrive transistor that supplies an overdrive potential to the sense amplifier, and a control circuit that changes a gate-source voltage of the overdrive transistor step by step. In the apparatus and method, a first X-ray for the X-ray fluoroscopy is generated intermittently. A vent groove is disposed in one of the mold parts and collects any gas trapped in the mold cavity. The invention will make water energy conversion systems more affordable and will turn existing and new bridge supporting structures into dual-use systems that can not only support bridge decks above but also produce useful renewable energy from the water below; today, bridge structures are not used in this manner. , in a manner that is safe and comfortable for grasping by a human hand. Thus, a more universal type of construction is possible that permits greater latitude in the associated equipment.