Abstract: A boat includes: a pair of buoyancy units spaced from each other; a bottom plate structure connecting the bottoms of the pair of buoyancy units to each other; and a water storage defined by the pair of buoyancy units and the bottom plate structure, open rearward at the stern to take water from the outside, and keeping the water flowing therein. The boat can keep the balance more stable, is free from a common waterproof problem, and can improve a running ability.

Abstract: There is provided a high speed solenoid having enhanced response characteristics. The high speed solenoid includes: a movable shaft linearly movable in an axial direction; a movable coil unit coupled to the movable shaft; and a magnetic field forming unit forming a magnetic field in a direction perpendicular with respect to that of a current flowing in the movable coil unit, wherein when a current is applied to the movable coil unit, the movable coil unit is moved by a magnetic field formed by the magnetic field forming unit to move the movable shaft. According to the high speed solenoid, the weight of a moving part is significantly reduced, and since an electrical time constant is small, a response speed of the solenoid may be enhanced.

Abstract: Disclosed is a NRD waveguide mixer adopting a ring hybrid coupler applicable to a small-sized and high functional millimeter wave receiving/transmitting device. The NRD waveguide has a housing including two parallel conductive plates. The ring hybrid coupler is installed in the housing and has an annular ring formed with first to fourth ports which are radially extended about the annular ring. An oscillating device is connected to the first port so as to generate a local oscillating signal. A rod antenna is connected to the second port so as to receive/transmit a radio frequency signal. A first balanced mixer mount is connected to the third port and is provided with a first Schottky diode. A second balanced mixer mount is connected to the fourth port and is provided with a second Schottky diode. The radio frequency signal and the oscillating signal inputted from the first and second ports are mixed in the ring hybrid coupler to be transformed into an addition signal and a subtraction signal.

Abstract: Disclosed is a NRD waveguide mixer adopting a ring hybrid coupler applicable to a small-sized and high functional millimeter wave receiving/transmitting device. The NRD waveguide has a housing including two parallel conductive plates. The ring hybrid coupler is installed in the housing and has an annular ring formed with first to fourth ports which are radially extended about the annular ring. An oscillating device is connected to the first port so as to generate a local oscillating signal. A rod antenna is connected to the second port so as to receive/transmit a radio frequency signal. A first balanced mixer mount is connected to the third port and is provided with a first Schottky diode. A second balanced mixer mount is connected to the fourth port and is provided with a second Schottky diode. The radio frequency signal and the oscillating signal inputted from the first and second ports are mixed in the ring hybrid coupler to be transformed into an addition signal and a subtraction signal.