• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.39-48
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• 2024

A car horn serves a crucial safety role as a means of communication between drivers and a part that alerts pedestrians in advance. While previous studies have utilized finite element method and electric circuit model to simulate and analyze characteristics of the car horns, there remains a lack of research on design methods of a trumpet horn. This paper presents a design approach that predicts the operating frequency based on the acoustic reactance at the throat of the horn, once the vibrating part is determined. We deal with a horn combining both an exponential horn and a waveguide in the acoustic section, and confirm that the acoustic reactance at the horn throat measured by impedance tube experiment agrees well compared with the numerical result obtained using the finite element method. The resonance frequency of the car horn is predicted using the COMSOL Multiphysics finite element numerical analysis model, and the proposed design method is validated by measuring the operating frequency of the designed horn in a sound pressure experiment. As a result, the resonance measured in a semi-anechoic chamber environment by applying a DC voltage of 12 [V] excluding the holder occurs accurately within a few [Hz] of the design operating frequency. This paper discuss the design method of a trumpet horn from the perspective of the horn's acoustic reactance, and is expected to be useful for designing horn systems.

• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.21-26
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• 1995

In this paper integral equations are derived and simulated numerically for the mutual radiation impedance of an acoustic transducer in a Plane array. It is assumed that the pistons are mounted in the rigid infinite baffle. The mutual radiation impedance is separated into resistance and reactance and plotted as a function of ka and kd. Mutual radiation resistance is decreased and perturbed according to increase of ka. Mutual radiation reactance is decreased along to increase of ka. Mutual impedance is decreased when kd is increased. However, when ka is 6, 13, and 19 the interaction effect is decayed. When the relative piston position of the two pistons is 45 degree, the amount of interaction becomes minimized.

• The Journal of the Acoustical Society of Korea
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• v.14 no.4
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• pp.82-88
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• 1995

Conductance and susceptance of the self-radiation impedance in a rectangular acoustic sensor without baffle are measured experimentally. Finite polyurethane window is mounted at the end of the acoustic sensor. The sensor radiation impedance is cauculated using the equivalent electric circuit. Using the Levine's integral equations of a rectangular piston mounted to the rigid infinite baffle, radiation resistance and reactance were simulated numerically. Numerical and experimental results are compared to each other.

• The Journal of the Acoustical Society of Korea
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• v.36 no.2
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• pp.108-114
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• 2017

We have experimentally analyzed the self-radiation impedance of an ultrasonic transducer with a square radiation surface that is used as a vibrator in underwater ultrasonic detection systems. The radiation reactance and the radiation resistance were measured in the range from 1 to 3 of ka that is the product of a wave number and a length of the edge of the square vibrator. By comparing the measured results with those of theoretical calculation of the radiation impedance using a series, we confirmed the validity of the experimental method and experimentally confirmed the variation trend in the radiation impedance of the square radiation surface.

• The Journal of the Acoustical Society of Korea
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• v.14 no.5
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• pp.58-62
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• 1995

Integral equations of self-radiation impedance of a rectangular piston in a rigid infinite baffle are derived using by polar coordinate. The self-radiation impedance is separated by two parts ; self-radiation resistance and self-radiation reactance. Derived integral equations are simulated by numerical method. Based on the numerical results, self-radiation impedance can be obtained in the low and high frequency ranges without any limited conditions.

• The Journal of the Acoustical Society of Korea
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• v.13 no.2
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• pp.23-29
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• 1994

In this paper, the measured in-water radiation impedance of cylindrical piezoelectric radiator with finite baffle is compared to the existing theoretical result of that with infinite baffle and the effect of baffle on the radiation impedance is examined. Comparision between measurement and theoretical result of radiation impedance shows that the measured radiation impedance tends to be that of the infinite baffle as the baffle length increases. Another finding of the comparision in that the effect of baffle is more dominant in radiation reactance than in radiation resistance. Therefore, for the use of theoretical radiation impedance of infinite baffle on the design of acoustic transducer, the impedance compensation to the baffle length should conducted.

• The Journal of the Acoustical Society of Korea
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• v.28 no.6
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• pp.491-498
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• 2009

This paper presents the design method of an impedance matching network using an isolation transformer and the Chebyshev filter function for the high efficiency and the flat power driving of an underwater acoustic piezoelectric transducer. The proposed impedance matching network is designed for minimizing the reactance component of transducer and having the flat power response in the wide frequency range. We design a low pass filter with ladder-type circuit using the Chebyshev function as standard prototype filter function. In addition, we design the impedance matching network which is suitable for the equivalent circuit of transducer and the turn ratio of transformer through the bandpass frequency transformation. The proposed method is applied to the simulated dummy load of the tonpilz-type transducer operating in the middle frequency range. The simulation results are compared with the measured characteristics and the validity of the proposed method is verified.

• Journal of KSNVE
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• v.6 no.3
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• pp.297-303
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• 1996

The general approach using sine series expansions was represented to evaluate the radiation loading from a vibrating surface on a simply supported cylinder. In this paper, the fluid-loading coefficients (radiation impedance) for a submerged finite cylindrical shell with an arbitrary end condition are defined and evaluated. The vibrations of cylindrical shell are expressed by using cosine series expansions to analyze the radiation impedance for a finite cylindrical shell. It is possible to represent the displacements at both ends of cylindrical shell in comparison with sine series. The direct and cross modal components of fluid-loading coefficients are shown and the validity of cosine series expansions are verified from the results of numerical computations. This approach and results are directly applicable in the analysis of sound radiation from subemerged finite cylindrical shell with arbitrary end conditions.