Center for Advanced Meta-materials

Pusan National University

Jjns Co., Ltd.

Korea Institute of Machinery & Materials

Jong Jin Park

Hak Joo Lee

Jun Hyuk Kwak

Kyung Jun Song

Hyun June Jung

Jae Hyun Kim

Shin Hur

Bong Kyun Jang

Se Jeong Won

Jun Ho Jeong

Kyung Sik Kim

Jae Hwa Lee

Eun Bok

Hyun Sung Park

Kyungjun Song

Tae In Choi

Min Seok Jung

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.

Acoustic metamaterial structure

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.

Fluid silencer

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.

Cover unit of ultrasonic transducer

Disclosed herein is a sound insulation panel which is easy to manufacture and has a light weight. The sound insulation panel includes: a patterned plate comprising an edge plate and a separation plate extending into an inner region of the edge plate and dividing the inner region into a first elastic region and a second elastic region; and an elastic plate protruding from the patterned plate to be stepped with respect to the patterned plate and including a first elastic plate disposed in the first elastic region and a second elastic plate disposed in the second elastic region, the elastic plate blocking an air flow path and converting airborne sound waves into elastic waves, wherein the first elastic plate and the second elastic plate are displaced in opposite directions at a resonant frequency of the sound insulation panel.

Sound insulation panel and sound insulation structure comprising the same

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.

Ultrasonic transmission structure

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.

Holographic-based directional sound device

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.

Sound insulation plate and sound insulation structure using the same

A graphene manufacturing device using Joule heating includes: a chamber having a space provided therein so as to synthesize graphene; and a first roller portion and a second roller portion disposed inside the chamber to be spaced from each other such that same support a catalyst metal penetrating the interior of the chamber and are supplied with an electric current for graphene synthesis, thereby Joule-heating the catalyst metal. In order to compensate for a temperature deviation of the catalyst metal passing between the first roller portion and the second roller portion, a first area of the catalyst metal, which is close to the first roller portion, and a second area of the catalyst metal, which is close to the second roller portion, are disposed to have movement paths facing each other.

Graphene manufacturing device and graphene manufacturing method using same

An embodiment of the present invention provides an ultrasonic wave amplifying unit which can improve ultrasonic power in air, wherein the ultrasonic wave amplifying unit includes multiple rings having a concentric axis and each having a first width, and a slit having a second width is formed between the rings and an air layer is formed between the multiple rings and an ultrasonic wave generator generating ultrasonic waves or a transfer medium transferring the ultrasonic waves.

Growing community of inventors

Sejong-si, South Korea

Jong Jin Park