Remote Localization of an Underground Acoustic Source by a PASSIVE Sonar System

Jarng, Soon Suck 대한원격탐사학회 1998 International Symposium on Remote Sensing Vol.14 No.1

The aim of the work described in this paper is to develop a complex underground acoustic system which detects and localizes the origin of an underground hammering sound using an array of hydrophones located about 100m underground. Three different methods for the sound localization will be presented, a time-delay method, a power-attenuation method and a hybrid method. In the time-delay method, the cross correlation of the signals received from the array of sensors is used to calculate the time delays between those signals. In the power-attenuation method, the powers of the received signals provide a measure of the distances of the source from the sensors. A new hybrid method has been developed for estimating the origin of the underground acoustic source by coupling both methods. The Nelder-Meade simplex search algorithm is then used to numerically estimate the position of the source in those methods. For each method the sound localization is carried out in three dimensions underground. The distance between the true and estimated origins of the source is in some cases less than 6m for a search area of radius 250m.

SEM Observation for the Damage of Inner Hair Cell Stereocilia of Guinea Pig Cochlea after Loud Tone Exposure

Jarng Soon Suck The Acoustical Society of Korea 2005 韓國音響學會誌 Vol.24 No.e1

The inner hair cell stereocilia of the guinea pig cochlea was examined under a scanning electron microscope (SEM) after loud tone exposure onto the ear drum of the animal. Before and after guinea pigs were exposed to intensive and continuous tone such as 106 dB SPL in intensity, the functioning of the cochlea was monitored by N1-N2 audiograms. The structural damage of the stereocilia of inner hair cells (IHCs) and outer hair cells (OHCs) was examined using the SEM in x 1500 magnification. The comparison between the functional change of the cochlea and the structural damage of the IHC stereocilia is done by means of photographic observation. It can be shown that the functional change might be related to the structural damage of the IHC stereocilia after intensive acoustic trauma.

Exterior Acoustic Holography Reconstruction of a Tuning Fork Using Inverse Non-singular BEM

Jarng, Soon-Suck The Acoustical Society of Korea 2003 韓國音響學會誌 Vol.22 No.e1

Non-singular boundary element method (BEM) codes are developed in acoustics application. The BEM code is then used to calculate unknown boundary surface normal displacements and surface pressures from known exterior near field pressures. And then the calculated surface normal displacements and surface pressures are again applied to the BEM in forward in order to calculate reconstructed field pressures. The initial exterior near field pressures are very well agreed with the later reconstructed field pressures. Only the same number of boundary surface nodes (1178) are used for the initial exterior pressures which are at first calculated by Finite Element Method (FEM) and BEM. Pseudo-inverse technique is, used for the calculation of the unknown boundary surface normal displacements. The structural object is a tuning fork with 128.4 ㎐ resonant. The boundary element is a quadratic hexahedral element (eight nodes per element).

A Study of Underground Sensing Technique Development for State Measurement of Underground Establishment

Jarng, Soon-Suck 조선대학교 에너지.자원신기술연구소 1999 에너지·자원신기술연구소 논문지 Vol.21 No.1

The aim of the work described in this paper is to develop a complex underground acoustic system which detects and localizes the origin of an underground hammering sound using an array of hydrophones located about l00m underground. Three different methods for the sound localization will be presented, a time-delay method, a power-attenuation method and a hybrid method. In the time-delay method, the cross correlation of the signals received from the array of sensors is used to calculate the time delays between those signals. In the power-attenuation method, the powers of the received signals provide a measure of the distances of the source from the sensors. A new hybrid method has been developed for estimating the origin of the underground acoustic source by coupling both methods. The Nelder-Meade simplex search algorithm is then used to numerically estimate the position of the source in those methods. For each method the sound localization is carried out in three dimensions underground. The distance between the true and estimated origins of the source is in some cases less than 6m for a search area of radius 250m.

Rotary Actuator Simulation by the Coupled FE-BE Method

Jarng, Soon-Suck,Kim, Young-Dong,Song, Cheol 조선대학교 에너지.자원신기술연구소 1998 에너지·자원신기술연구소 논문지 Vol.20 No.2

This paper describes the application of the finite element method (FEM) to obtain the steady-state response of a piezoelectric rotary actuator. The rotary actuator is three-dimensionally simulated to transduce applied electrical charge on axial surfaces of the piezoelectric ring to rotational displacement. The rotational displacement of the rotary actuator is shown in temporal motion. Some technical consideration for simulating the rotary actuator in the FEM is described. The resultant motion of the rotary actuator is like a surface acoustic wave (SAW) as expected. The boundary element method (BEM) is also coupled with the FEM in order to simulate the sound radiation generated by the roray actuator in the air. The coupled FE-BEM is described in detail.

Tuning Fork Modal Analysis and Sound Pressure Calculation Using FEM and BEM

Jarng, Soon-Suck,Lee, Je-Hyung The Acoustical Society of Korea 2002 韓國音響學會誌 Vol.21 No.e3

An unconstrained tuning fork with a 3-D model has been numerically analyzed by Finite Element Method (FEM) and Boundary Element Method (BEM). The first three natural frequencies were calculated by the FEM modal analysis. Then the trend of the change of the modal frequencies was examined with the variation of the tuning fork length and width. An formula for the natural frequencies-tuning fork length relationship were derived from the numerical analysis results. Finally the BEM was used for the sound pressure field calculation from the structural displacement data.

Development of Underground Acoustic Noise Rejection Method

Jarng, Soon Suck,Park, Jong An,Lee, Kang Hyun CHOSUN UNIVERSITY 1997 Basic Science and Engineering Vol.1 No.2

Underground acoustics could be applied for the detecton of the underground noise. Unlike underwater acoustics, experimental measurements of underground acoustical noise are not much published at present. In the near future, it is clearly expected that there would be more requirements for research activity in the area of underground acoustics. It is because of the infinite potential of underground development. This paper presents the results of experimental measurements of underground acoustical noise. The procedure of experimental methods is described in detail. It was observed that 60Hz ground noise was certainly detected because of the electrical potential difference between the earth surface and the bottom of a 60M deep water-filled tunnel of 15cm diameter. Since a hydrophone is located inside the water-filled tunnel for acoustic sensing, such a ground noise of potential difference is induced. A solution of the problem is suggested. The detection of the surface shock is carried out by the hydrophone with some quantitative analysis.

Power Method Development for Underground Hammering Origin Localization

Jarng, Soon-Suck 조선대학교 에너지.자원신기술연구소 1997 에너지·자원신기술연구소 논문지 Vol.19 No.2

The aim of this paper is to develope a complex underground acoustic system which detects and localizes the origin of an underground hammering sound using an array of hydrophones located 80M underground. A new method for the sound localization will be presented. Powers of the acoustic signals received from the array of sensors are calculated for considering of their power distribution against distance. And then the algorithm of the Nelder-Meade simplex search method is used for numerically estimating the origin of the underground hammering shock. The present method for the sound localization is carried out in three dimension underground. In some case, the difference between the true origin and the estimated origin of the hammering shock is less than 16M while 250M radius of underground area is examined. Also the spectra of the multi-channel signals are analyzed to classify the type of the underground hammering.

Measurements for Underground Propagation Velocity and Material Attenuation Coefficients

Jarng, Soon-Suck,Song, Chol,Lee, Je-Hyeong CHOSUN UNIVERSITY 1997 Basic Science and Engineering Vol.1 No.2

It is necessary to measure a propagation velocity and attenuation coefficients of underground mediumistic materials for the purpose of underground resource exploration and/or underground material research. In the present study, such a propagation velocity and an attenuation coefficient of -0.0055 were measured by means of hammering shock on the ground surface 16M apart from an entrance of an underground tunnel of which on the bottom a hydrophone was located. The sensitivity of the hydrophone was quantitatively analyzed on the onset of the hammering shock on the ground surface.

A New Method for Underground Acoustic Positioning

Jarng, Soon-Suck CHOSUN UNIVERSITY 1997 Basic Science and Engineering Vol.1 No.2

The aim of this paper is to develop a complex underground acoustic system which detects and localizes the origin of an underground hammering sound using an array of hydrophones located 80m underground. A new method for the sound localization will be presented. powers of the acoustic signals received from the array of sensors are calculated for considering of their power distributio against distance. And then the algorithm of the Nelder-Meade simplex search method is used for numerically estimating the origin of the underground hammering shock. The present method for the sound localizatio is carried out in three dimension underground. In some case, the difference between the true origin and the estimated origin of the hammering shock is less than 16M while 250M radius of underground area is examined. Also the spectra of the multi-channel signals are analyzed to classify the type of the underground hammering.