Abstract:
In a piezoelectric speaker, an acoustic diaphragm is thicker than a piezoelectric thin film and is formed of a more flexible and higher elasticity material than the piezoelectric thin film, thereby greatly improving output sound pressure in a low frequency band and reducing sound distortion. Further, the piezoelectric thin film is attached to the acoustic diaphragm in an inclined structure in which the piezoelectric thin film is horizontally turned from the acoustic diaphragm, thereby preventing a standing wave from being created by structural symmetry and minimizing sound distortion.
Abstract:
A security system and a method of determining whether there is an intrusion are provided. A correlation between sound signals obtained from a sound source generating device and a sound-field variation measuring device is used to measure a acoustic field in a certain space. A difference between an initially set acoustic field and a changed acoustic field is used to determine whether there is an intruding object in a certain space. The security system includes a sound source generating device for generating a sound source; and a sound-field variation measuring device for measuring a acoustic field formed by the sound source, wherein an initially set acoustic field is compared with the measured acoustic field to determine whether there is an intrusion.
Abstract:
Provided is near-field optical probe including: a cantilever arm support portion that is formed of a lower silicon layer of a silicon-on-insulator (SOI) substrate, the cantilever arm support portion having a through hole formed therein at a side of the lower silicon layer; and a cantilever arm forming of a junction oxidation layer pattern and an upper silicon layer pattern on the SOI substrate that are supported on an upper surface of the lower silicon layer and each have a smaller hole than the through hole, a silicon oxidation layer pattern having a tip including an aperture at a vertical end, corresponding with the hole on the upper silicon layer pattern, and an optical transmission prevention layer that is formed on the silicon oxidation layer pattern and does not cover the aperture.
Abstract:
Provide is a forced acoustic dipole in which a direction of an acoustic lobe can be freely steered by controlling phase and sound pressure of input signals input into first and second sound sources, respectively. Accordingly, when a forced acoustic multipole array is configured by arranging a plurality of forced acoustic dipoles and a direction of an acoustic lobe is steered in a particular direction by controlling phase and sound pressure of input signals input into the first and second sound sources, respectively, it is possible for a sound to be heard in a desired location without auditory disturbance to others.
Abstract:
An ultra-small optical/magnetic head actuator includes: a swing arm movable in a horizontal direction (tracking direction) and a vertical direction (focusing direction) and having mounted thereon a head for reading and writing information on a disk. A tracking actuator moves the swing arm in the horizontal direction (tracking direction) and a pivot hinge adjusts a radius of rotation of the swing arm and guides the movement of the swing arm in the tracking direction. A focusing actuator moves the swing arm in the vertical direction (focusing direction), wherein the focusing actuator includes a focusing coil attached under the swing arm and a Halbach magnet array disposed under the focusing coil minimizes thickness. Friction or backlash can be avoided, and non-repetitive errors can be reduced. The thickness of the ultra-small storage device can be reduced due to the use of a Halbach magnet array.
Abstract:
An apparatus capable of tracking a sample surface level in a z direction and oscillating a cantilever at resonant frequency by using a frequency separation scheme in non-contact mode and method thereof. The inventive apparatus includes a sensing unit for sensing a sample surface; a frequency transforming unit for transforming the sensed signal; a frequency combining unit for combining signals; and an actuating unit for actuating the sensing unit.
Abstract:
Disclosed is a high directive ultrasonic transducer that can concentrate a radiated ultrasonic wave in one direction by making an orientation angle of the radiated ultrasonic wave small in an ultrasonic transducer having a planar radiation plate structure, which has high radiation efficiency in an air medium. The high directive ultrasonic transducer according to the present disclosure includes a planar radiation plate configured to radiate an ultrasonic wave into a medium; a driving unit configured to vibrate the radiation plate in a higher order mode of a secondary order or more by applying predetermined force to a bottom surface of the radiation plate; and a matching layer formed in a height corresponding to 1/4 of an ultrasonic wavelength in the medium, in a part having a positive vibration velocity on a top surface of the radiation plate.
Abstract:
Disclosed is a system of transferring wireless power using an ultrasonic wave, including: an ultrasonic wave generating device converting and transferring electric energy to an ultrasonic wave; and an ultrasonic wave receiving device receiving the ultrasonic wave to convert the ultrasonic wave to electric energy, wherein the ultrasonic wave generating device includes a radiation plate with a plurality of ultrasonic elements and controls an effective area of the radiation plate by turning on/off the plurality of ultrasonic elements so that the ultrasonic wave receiving device is disposed at a position minimizing dispersion effect due to a circular radiation of the ultrasonic wave.
Abstract:
In a folding-type directional speaker array module, when sound is output, the directionality of a high frequency band can be obtained through a center speaker module and the directionality of a low frequency band can be obtained through side speaker modules unfolded from both sides of the center speaker module. Accordingly, the speaker array module has excellent directionality in an entire frequency band. Furthermore, the folding-type directional speaker array module has high mobility and portability because the side speaker modules are folded and stored when the folding-type directional speaker array module is not used.
Abstract:
In a piezoelectric speaker, an acoustic diaphragm is thicker than a piezoelectric thin film and is formed of a more flexible and higher elasticity material than the piezoelectric thin film, thereby greatly improving output sound pressure in a low frequency band and reducing sound distortion. Further, the piezoelectric thin film is attached to the acoustic diaphragm in an inclined structure in which the piezoelectric thin film is horizontally turned from the acoustic diaphragm, thereby preventing a standing wave from being created by structural symmetry and minimizing sound distortion.