Abstract: The present invention provides an underground-environment simulator which simulates underground environment spaces used for radioactive waste disposal or the like, and has a hermetic box, wherein the carbon dioxide gas concentration inside the box can be adjusted to an optional level, and the atmosphere inside the box can be uniformly and stably maintained. In the underground-environment simulator of the present invention, a carbon dioxide gas feeding means feeds carbon dioxide gas into a circulating gas circulation which controls the atmosphere inside the hermetic box, and the concentration of carbon dioxide gas in the circulating gas is measured and adjusted to a predetermined level while oxygen is removed from the circulating gas in an oxyhydrogen reactor. Accordingly, the carbon dioxide gas concentration can be controlled within a low concentration range, and various underground environments can be accurately simulated by varying the carbon dioxide gas concentration to an optional level.

Abstract: An ultrasonic air humidifying apparatus comprising separably connected upper and lower cabinets; a power transformer, high frequency generator and motor-blower contained in the upper cabinet; a water vessel formed in the lower cabinet; a chassis board interposed between the upper cabinet and lower cabinet so as to define an airtight space above the surface of water in the water vessel; a mist conduit pipe fixed to the chassis board, inserted at the lower end into the water in the water vessel and projected at the upper end out of the top part of the upper cabinet; an ultrasonic vibrator assembly fitted to the lower end of the mist conduit pipe; and a water supply tank removably fitted in the upper cabinet so as to supply water into the water vessel, in order to obtain an ultrasonic air humidifying apparatus easy to clean and inspect and high in the performance.