Abstract: Disclosed is a customizable toothbrush produced in a real-time corresponding to a teeth structure of a user. The customizable toothbrush includes a silicone brush head, a sonic body, bristles, a conjoining unit, and occlusal stoppers. The silicone brush head is fabricated by negative shape/investing by utilizing an algorithm associated with additive manufacturing. The negative investing is obtained through scan model of the teeth structure captured by the direct intraoral scanner. The sonic body creates an oscillation motion while brushing the teeth. The bristles are arranged over the silicone brush head to clean the teeth structure. The conjoining unit joins the silicone brush head with the sonic body. The occlusal stoppers are placed into the silicone brush head to stabilize the silicone brush head in an oral cavity of the user. The occlusal stoppers allow the user to bite down on the silicone brush head at a desired position while brushing.

Abstract: Disclosed is a propulsion system and a rocket having the same. The propulsion system includes: a combustion tube having a propellant therein; a nozzle installed at a rear end of the combustion tube, and configured to discharge combustion gas generated when the propellant is ignited; and a nozzle separation unit coupled to the combustion tube and the nozzle, respectively, and configured to mount the nozzle to the combustion tube, and configured to separate the nozzle from the combustion tube as at least part thereof melts when reaching a preset temperature.

Abstract: Disclosed is a propulsion system and a rocket having the same. The propulsion system includes: a combustion tube having a propellant therein; a nozzle installed at a rear end of the combustion tube, and configured to discharge combustion gas generated when the propellant is ignited; and a nozzle separation unit coupled to the combustion tube and the nozzle, respectively, and configured to mount the nozzle to the combustion tube, and configured to separate the nozzle from the combustion tube as at least part thereof melts when reaching a preset temperature.