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Acoustic Duct 내부에 장착된 아이오노머의 이온기 변화에 따른 흡음패턴 측정
장순석,김준섭,이제형,박재철 조선대학교 전자정보통신연구소 2001 電子情報通信硏究所論文誌 Vol.4 No.2
Nowadays, as the industrial technology and instrumentation are developed, the interest of the characteristic improvement of sound absorbing materials is rising. Recently new sound absorbing materials are being developed and manufactured for commercialization. But most of sound absorbing materials are polymer-typed or are fabricated by polymers (mixtures of polymer and glass fiber, asbestos...) for better physical characteristic. However, there was not much research about sound absorption change by the change of the ionic nature. In this paper, I composed polymers that include alkaline or acid, or other polymer that have the ionic nature to improve sound absorption characteristic and searched the characteristic pattern of the sound absorption of polymer. I used probe microphone instead of 1/4 condenser microphone such as two- microphone method in order to measure in-duct absorption coefficient of specimen of ionomers that are thin and small so that measuring absorption coefficient is not well defined.
격음 노출 후 기니픽 달팽이관내 내유모세포 부동섬모 손상 정도의 SEM에 의한 관찰
장순석 조선대학교 동력자원연구소 1997 動力資源硏究所誌 Vol.19 No.1
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 animals. 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 x1500 magnification. The preparation of the cochlear specimen is explained in detail. 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.
움직이는 물체의 거리 및 속도 측정을 위한 고전력 쏘나 시스템 개발
장순석,안홍구,이제형 조선대학교 에너지.자원신기술연구소 1999 에너지·자원신기술연구소 논문지 Vol.21 No.2
This paper aims for the development of the high power sonar system for measuring the distance and the velocity of a moving object. The high power sonar system transmits two gated 190 KHz sinusoidal signals with 1.6〔ms〕 time interval to the moving object. Then the sonar system detects and calculates the changed time delay of the reflected ultrasonic signals in order to derive the velocity of the moving object. The transmission part uses a high power amplifier so that 250W gated sinusoidal signals can be transmitted to the transmitter. 1M RAM is utilized for transmitting and storing of the ultrasonic signals. The time delay is calculated by the cross-correlation technique between the transmitted signals and the received signals. The measured value from the high power sonar system is compared with directly measured values by photo diodes. The result confirms the adjacency to 0.3% error.
이우선,조금배,장순석 조선대학교 에너지.자원신기술연구소 1999 에너지·자원신기술연구소 논문지 Vol.21 No.1
We have been fabricated the high voltage TFT(HVTFT) having output voltage of l00V. The hysteresis curves occurred in the HVTFT. Hysteresis charactristics measured in the range of drain voltage of l00V, gate voltage of 100V. Drain current Id showed negative current characteristic a t high gate voltage. We found that the according to the forward voltage Vg increase, the drain current Id decreased. And the reverse voltage Vg decreased exponentially with the drain current Id. The hysteresis region occurred mare larger at high voltage. According to the Vd increase, Id (on/off) ratio decreased exponentially.
Optimal Design of Deep-water 30kHz Omnidirectional Sonar Transducer Using a Coupled FE-BEM
Jarng, Soon-Suck The Acoustical Society of Korea 1999 韓國音響學會誌 Vol.18 No.e4
Deep-water sonar transducers of FFR (Free Flooded Ring) type have been designed using a coupled FE-BEM. The proposed sonar transducers are composed of piezoelectric ceramic tubes and structural steel materials for simple fabrication. In order to have an omnidirectional beam pattern around 30kHz, a conic steel is placed below a piezoelectric tube or a steel disc is placed between two piezoelectric tubes. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Various results are available such as directivity patterns and transmitting voltage responses. The most optimal structure and dimensions of the steel material were calculated, so that the beam patterns of the sonar transducers had +/- 3dB omnidirectivity at 30kHz.
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.
In-water SONAR shell transmitter simulation using a coupled FE-BE method
Jarng, Soon-Suck The Korea Institute of Information and Commucation 1998 한국정보통신학회논문지 Vol.2 No.1
This article describes the application of a coupled finite element-boundary element method to obtain the steady-state response of a sonar transducer. The particular structure considered is a flooded piezoelectric spherical shell. The sonar shell is simulated to be driven by electrical charges applied onto inner and outer surfaces of the shell. It is shown that at relatively low input frequency a beam pattern which is almost close to omnidirection can be obtained. The coupled FE-BE method is described in detail.
Jarng, Soon-Suck The Acoustical Society of Korea 1999 韓國音響學會誌 Vol.18 No.e2
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. In the hybrid method, both informations of time-delays and power-ratios are coupled together to produce better performance of position estimation. A new acoustic imaging technique has been developed for improving the hybrid method. This new acoustic imaging method shows the multi-dimensional distribution of the normalized cost function, so as to indicate the trend of the minimizing direction toward the source location. 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 28m for a search area of radius 250m.
PZT4 Sonar Shell transmitter Simulation Using a Coupled FE-BE Method
Jarng, Soon-Suck The Acoustical Society of Korea 1998 韓國音響學會誌 Vol.17 No.e1
This article describes the application of a coupled finite element-boundary element method to obtain the steady-state response of a sonar transducer. The sonar shell is simulated to be driven by electrical charges applied onto inner and outer surfaces of the shell. It is shown that at relatively low input frequency a beam pattern which is almost close to omnidirection can be obtained. The coupled FE-BE method is described in detail.