Abstract: An exemplary embodiment provides matching media for perfect transmission of ultrasonic waves by easily implementing perfect transmission of ultrasonic waves at a boundary between different elastic media through a matching layer provided at the boundary between the different elastic media and proposes a matching layer having a single layer structure of a simple single pattern that is easily processed, thereby easily implementing effects such as miniaturization of the matching layer, reduction of manufacturing cost, and improvement of manufacturability.

Abstract: A fluid silencer includes: an expansion pipe disposed on a pipe through which a fluid containing noise sources flows and having an accommodation space therein; a viscous fluid received in the accommodation space; a noise introducing member disposed between the pipe and the expansion pipe to seal the accommodation space and allowing the noise sources to be introduced into the accommodation space therethrough; at least one partition member disposed in the accommodation space and dividing the accommodation space in a flow direction of the fluid; multiple baffle members disposed on one surface of the partition member and forming multiple sound absorbing spaces into which the noise sources introduced into the accommodation space are dispersedly introduced; and an elastic member disposed between the partition member and the baffle members and contracted/expanded by the viscous fluid entering/leaving the sound absorbing spaces as the noise sources are introduced into the sound absorbing spaces.

Abstract: Disclosed herein is an acoustic metamaterial structure which can effectively reduce noise in a specific frequency range through formation of an acoustic bandgap, wherein the specific frequency range is determined by a periodic structure formed by an array of multiple unit cells. The acoustic metamaterial structure includes multiple first unit cells each including a first space having a first cross-sectional area and a second space disposed downstream of the first space in a flow direction of fluid to communicate with the first space, the second space having a second cross-sectional area larger than the first cross-sectional area, wherein the acoustic metamaterial structure reduces noise in a specific frequency range through formation of an acoustic bandgap, the specific frequency range being determined by a periodic structure formed by an array of the first space and the second space.

Abstract: Disclosed herein are a metastructure having a zero elastic modulus zone, which can experience constant stress in a predetermined strain zone, and a method for designing the same. The metastructure includes a first unit and a second unit, wherein the first unit has a structure capable of buckling and has a stress-strain relation having a zone corresponding to a negative elastic modulus, the second unit is disposed adjacent to the first unit and has a stress-strain relation having a zone corresponding to a positive elastic modulus, and the metastructure has zero elastic modulus in a predetermined target strain zone through synthesis of the negative elastic modulus of the first unit with the positive elastic modulus of the second unit.

Abstract: A carrier substrate includes a base layer, an antireflection layer, and an energy absorption layer, wherein the antireflection layer is formed on one surface of the base layer and allows an elastic wave generated by a first laser beam transmitted through an element adhesively bonded to the antireflection layer to be transmitted through the base layer without being reflected towards the element, the first laser beam being applied to the element through a source substrate of the element, and the energy absorption layer is formed between the base layer and the antireflection layer to be aligned with the element, and evaporates upon energy absorption.

Abstract: A cover unit includes: a body to which an ultrasound generator adapted to generate ultrasound is coupled; first slits disposed at a lower portion of the body in the form of multiple rings having different radii and spaced apart from each other, the first slits having a first width; second slits depressed from an upper surface of the body to communicate with the first slits and having a second width smaller than the first width; third slits depressed from the upper surface of the body and each disposed between adjacent second slits, the third slits having a third width smaller than the first width; a bottom formed under the first slits; a first sidewall formed between adjacent first slits; and a second sidewall formed between the second slit and the third slit.

Abstract: The provided is an ultra-wideband electromagnetic wave absorber having a hexagonal double layer structure, and in the ultra-wideband electromagnetic wave absorber, the first conductive pattern disposed on the top of the first dielectric layer and the second conductive pattern disposed on the top of the second dielectric layer are arranged in an up-down double layer structure, thereby expanding the electromagnetic wave absorption bandwidth, and even when applied to a corner or a curved structure forming 60° or 120° by hexagonal unit cells, the unit cells can be periodically arranged at the same interval. In addition, since dielectrics with a difference of less than 10% in dielectric constant in a vacuum state have a relatively low specific gravity, the overall weight can be made very light by using such dielectrics in the first dielectric layer and the second dielectric layer.

Abstract: Disclosed herein is a meta-muffler for reducing broadband noise. The meta-muffler includes: a flow pipe through which a fluid flows; an outer barrel disposed outside the flow pipe to be spaced apart from the flow pipe; and multiple metastructures arranged in a flow direction of the fluid and each comprising an opening opened parallel to the flow direction of the fluid, a resonance chamber disposed between the flow pipe and the outer barrel and communicating with the flow pipe through the opening, and a neck adjustment member extending from the outer barrel toward the flow pipe to be spaced apart from the opening in the flow direction of the fluid. The meta-muffler can increase transmission loss of noise flowing through the flow pipe through maximization of energy loss of sound waves entering the resonance chamber of the metastructure and can effectively attenuate noise over a wide band ranging from low frequencies to high frequencies.

Abstract: In a wave focusing device and a wave emitting device having the wave focusing device, the wave focusing device has a plurality of filters and focuses a wave by a phase overlap. The plurality of filters includes a first filter formed on a substrate, a second filter formed on the substrate and overlapping with the first filter in a first area, and a third filter formed on the substrate and overlapping with the second filter in a second area. A size of the first area is substantially same as that of the second area. A first portion of the second filter in the first area is inverted to a second portion of the second filter in the second area, with respect to a first axis. A wave passing through the wave focusing device is focused at a center of each of the first, second and third filters.

Abstract: The present invention relates to lithium metal oxide nanoparticles and a method for preparing the same and provides lithium metal oxide nanoparticles each having a shape of a hexahedron with a square outer cross section or a hexahedron with at least one chamfered corner and comprising a hollow of which a cross section is a square or a square having at least one chamfered corner, and a method for preparing the same, so that the lithium metal oxide nanoparticles can be utilized as an electrode material of a next-generation electronic device in which a contact area between an electrode and an electrolyte is increased to improve the charge and discharge rate characteristics and improve the conductivity.

Abstract: A method for transferring a micro device on a curved surface according to an exemplary embodiment of the present invention includes: coating an adhesive layer on an external circumferential surface of a tube; providing a micro device pattern on one side of a substrate; positioning an external circumferential surface of the tube to contact the substrate and allow a length direction of the device pattern to cross a radius direction of the tube, and rotating the tube with respect to an axis-direction of the tube and simultaneously moving at least one of the tube and the substrate in a rectilinear way to transfer the micro device pattern on the substrate to the adhesive layer; and fixing the transferred micro device pattern to the adhesive layer by curing the adhesive layer.

Abstract: A sound wave delivery structure of the present invention comprises unit structure cells each formed to have a cubic shape and comprising a column portion formed on a region corresponding to sides, and a space portion formed in an internal region surrounded by the column portion. There are a plurality of unit structure cells which are successively arranged in a first direction, in which sound waves are delivered, and a second direction crossing the first direction.

Abstract: A 5G band transmissive body includes a base substrate and a pattern portion, wherein the pattern portion is provided on one side of the base substrate and transmits the 5G communication frequency band, and includes a conductive pattern formed by providing a conductive material on a plurality of virtual grid cells arranged in the horizontal and vertical directions, and a plurality of unit areas divided by a virtual vertical line and a virtual horizontal line, which are orthogonally crossing at center of the pattern portion, and a pair of virtual diagonal lines and crossing each other at the center and passing through the corners of the pattern portion, and the conductive pattern is symmetrical with respect to each of the vertical line, horizontal line, or diagonal line in the neighboring unit areas among the plurality of unit areas.

Abstract: A transparent stealth structure includes: a first transparent film structure stacked on a front surface of a transparent base, the first transparent film structure causing energy loss of incident electromagnetic waves having a target frequency to change a phase of transmitted electromagnetic waves propagating toward the transparent base; and a second transparent film structure stacked on a back surface of a transparent base, the second transparent film structure reflecting the transmitted electromagnetic waves having passed through the transparent base while adjusting a phase of reflected waves propagating toward the first transparent film structure, wherein the first transparent film structure includes a first front transparent conductive pattern having a first sheet resistance and a second front transparent conductive pattern filling a region, and the second transparent film structure includes a first rear transparent conductive pattern having a third sheet resistance and a second rear transparent conductiv

Abstract: The present disclosure provides an acoustic metamaterial-based muffler for exhaust noise reduction, including an exhaust flow body that is provided with an inlet through which exhaust gas of an internal combustion engine flows in on one side, and an outlet through which the exhaust gas flows out on the other side, and a flow passage for guiding a movement of the exhaust gas therein; and a plurality of noise reduction units that are sequentially disposed along a discharge direction of the exhaust gas inside the exhaust flow body to reduce noise in a specific frequency band in exhaust noise of the exhaust gas caused by the movement of the exhaust gas on the inside of the exhaust flow body.

Abstract: Disclosed is an ultrasonic wave transmission structure which is provided on a path of ultrasonic waves to amplify incident ultrasonic waves. The ultrasonic wave transmission structure includes: multiple rings each provided with a body portion having a different radius from other body portions and spaced apart from another body portion adjacent thereto and a slit disposed between adjacent body portions; and a membrane disposed in the multiple rings, wherein the mass of the membrane is adjusted to vary a resonant frequency in multiple sub-membrane regions.

Abstract: A holographic-based directional sound device is provided, the device including: a sound wave generating means generating a sound wave; and a flat plate configured to have the sound wave generating means installed at the center so as to radiate the sound wave to the outside through a surface, and to be composed of a plurality of unit cells, in which at least one groove is formed on a surface of the unit cell, and a radiation angle of the sound wave is determined according to a depth of the groove with respect to the unit cell, wherein the depth of the groove is determined by an individual surface admittance calculated by a cosine function or a sine function of the sum of a first value and a second value on the basis of a preset radiation angle of the sound wave and a preset frequency of the sound wave.

Abstract: The present invention relates to a metal-organic framework and an energy storage system having the same, and more specifically, to an energy storage system that is capable of providing excellent electrical conductivity and electrochemical capacity properties, especially excellent electrochemical performance at low temperatures, by means of a novel one-dimensional metal-organic framework having thianthrene-based organic ligands.

Abstract: A sound insulation plate includes a patterned frame and an elastic membrane, wherein the patterned frame includes a central pattern region and multiple peripheral pattern regions arranged around the central pattern region, the multiple peripheral pattern regions being separated from the central pattern region by a separation bar, and wherein the elastic membrane is mounted on the patterned frame to block passage of air and converts airborne sound waves into elastic waves.

Abstract: The present invention relates to a device for converting a frequency of an electromagnetic wave and, more specifically, to a device for converting an original frequency of an electromagnetic wave into a frequency corresponding to a resonator mode by using a time-varying Fabry-Perot resonator including a time-varying reflective surface of which reflectivity changes with time.