• The Journal of the Acoustical Society of Korea
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• 제25권3E호
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• pp.95-100
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• 2006

The present study presents the design procedures and the acoustic properties of the main hall of Ansan Cultural Arts Center in Korea which has opened in 2004. The acoustic design values are compared with the measured acoustic properties of the completed multi-purpose hall. Acoustic design criteria were suggested in the design stage through the 3-dimentional computer simulations. The acoustic parameters including SPL, RT, C80, $D_{50}$M, RASTI were measured in the hall after completed. Acoustic measurements were carried out in the 40 measurement points using MLS sound source signal in 4 different sound source points. The results show the even distribution of sound levels within the 2.0dB of difference among all seats. The reverberation time of 1.66sec was measured which is similar to the objective value of 1.65 sec in empty states. It was also found that average C80 values lie in the objective extents of C80 from -1 to 3dB and average D50 value of 54 was measured. Thus, it is concluded that the hall can be used as a multi-purpose hall with a suitable acoustic conditions.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 추계학술발표대회
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• pp.97-100
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• 2011

Underwater Wireless Acoustic Sensor Networks have become an important area of research over the recent decades. Designing an underwater network, especially a media access control (MAC) protocol, faces many challenges due to the peculiarities of underwater environment. One of the most important problems is resulted from long and variable propagation delay of the acoustic wave. In this paper, we propose a new method, namely Dynamic Timeout over Multiple Access with Collision Avoidance (DT/MACA), which is designed to handle long and high variable propagation delay in underwater acoustic sensor networks. In this proposed method, the difference timeout intervals are evaluated and applied to each network transmission. Simulation results show that our work not only improves the network throughput, but also decreases the unnecessary retransmission and end-to-end delay.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.159-171
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• 1997

Sound intensity distributions and energy flow in the near field of dipole source system and flat plate were investigated. First, the effectiveness of complex acoustic intensity was proved by using mathmatical and experimental methods in order to inden- tify noise sources and transmission paths of dipole field which is effected by the presence of neighbouring coherent sources. Next, analytical complex acoustic intensity method was discussed and the characteristics and energy flow of sound induced from the plate are clarified. The velocity of plate obtained from Finite Element Method was used for calculation of complex acoustic intensity in the near field. Finally experimental complex acoustic intensity method using both of active and reactive intensity is vital in devising a strategy for the identification and the reduction of vibration and noise.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.474-481
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• 2000

recently out-door stadium have been built not only for athletic sports but also various events and huge concerts and 50% of the roof of multi-purpose stadium have been covered by dome and the tendency of this kind of building type gradually increase, in spite of this kind of building tendency, the appearance of acoustic obstacle is serious and have little solution of this problem in acoustic-prevent building field. The purpose of this study is for analysis of acoustic Properties(SPL, RT60, RASTI) and answering of characteristics of echo through acoustic computer simulation in Seoul world cup stadium in the first instance.

• 한국음향학회지
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• 제24권1호
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• pp.21-28
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• 2005

본 논문에서는 장방형 콘서트홀에서 무대천장높이 변화가 객석의 음향성능에 미치는 영향에 대하여 조사하였다. 먼저 컴퓨터 시뮬레이션을 사용하여 객석부에서의 음향 특성을 조사하기 위하여 대표적 장방형 콘서트홀인 Boston Symphony Hall (이하 BSH)의 단순화 모델을 적용하였다. 또한 신축된 400석 규모의 장방형 홀의 축소모형 $(1.2m{\times}0.68m{\times}0.31m)$ 실험과 축소모형의 시뮬레이션을 통하여 무대부 천장높이의 변화에 따른 객석에서의 음향특성의 영향을 측정하였다. 실험 결과, 컴퓨터 시뮬레이션과 축소모형실험 및 축소모형실험의 시뮬레이션에서 모두 무대천장높이가 낮아질수록 잔향시간이 증가하는 경향을 보였으며, 무대천장 높이에 따른 잔향시간의 변화율은-0.09[sec/m]$\~$-0.061[sec/m]로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.763-766
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• 2004

Recently, various acoustic artifacts that contains speaker have been produced such as cellular phone. Speaker consists of diaphragm generating sound and coil vibrating diaphragm. Generally, good speaker means that it has a wide frequency range, high output power rate to input power and flat sound pressure level in specified frequency range. Acoustic characteristic was estimated through the experiment and computer simulation, or sound power was controlled with acoustic sensitivity in a natural frequency range fer last decade. However, the flatness of sound pressure level has not been considered to enhance the sound quality of a speaker. Tn this study, a method for speaker design is proposed for a good acoustic characteristic, which is flatness of SPL(sound pressure level) and wideness between the first and second natural frequency. SYSNOISE is used fer acoustic analysis and ANSYS is used for harmonic response analysis and modal analysis. Optimization for acoustic characteristics of a speaker diaphragm is performed using ModelCenter. All analyses are done within a frequency domain. And we confirm that the experimental and computational simulations have similar trend.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.239-260
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• 2023

The underwater acoustic wireless communication networks are generally formed by the different autonomous underwater acoustic vehicles, and transceivers interconnected to the bottom of the ocean with battery deployed modems. Orthogonal frequency division multiplexing (OFDM) has become the most popular modulation technique in underwater acoustic communication due to its high data transmission and robustness over other symmetrical modulation techniques. To maintain the operability of underwater acoustic communication networks, the power consumption of battery-operated transceivers becomes a vital necessity to be minimized. The OFDM technology has a major lack of peak to average power ratio (PAPR) which results in the consumption of more power, creating non-linear distortion and increasing the bit error rate (BER). To overcome this situation, we have contributed our symmetry research into three dimensions. Firstly, we propose a machine learning-based underwater acoustic communication system through long short-term memory neural network (LSTM-NN). Secondly, the proposed LSTM-NN reduces the PAPR and makes the system reliable and efficient, which turns into a better performance of BER. Finally, the simulation and water tank experimental data results are executed which proves that the LSTM-NN is the best solution for mitigating the PAPR with non-linear distortion and complexity in the overall communication system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.623-627
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• 2007

In case of the Grand Performance Hall, in view of its distinctiveness, since various Assembly Activity as well as Lecture together with the use for Music are important besides the purpose of Performance itself, the consideration with regard to the sound environment which enables to minimize the acoustic defect has appeared on the stage as an essential factor. On this viewpoint, this Study has attempted to examine the acoustic satisfaction degree and its response regarding to the grand performance hall by means of the measurement and valuation about the psychological volume of human-being using the auditory-evoked technology that possible to experience the Virtual Sound Field at the designing stage, after practice of the optimized acoustic design for the object of the grand performance hall on the step of construction. As the result of auditory-evocation, it was known that the valuation about the acoustic performance after reformation has been improved affirmatively than before reformation. It is considered that such outcome of the study could be utilized as the useful material that enables to improve the curtailment effect of construction cost and the acoustic performance, by means of the presupposition control about the acoustic problem from the stage of design, for the occasion when the similar Performance Hall is planning to build, hereafter.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.7-10
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• 2000

This paper focuses on the development of speech enhancement techniques for hands-free audio terminals, including two major problems : noise cancellation and acoustic echo cancellation. The objective is to find a joint structure to get a near-end speech signal with minimum distortion and low levels of echo and noise. To solve the two problems, a new promising technique is studied and tested in computer simulation conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.558-563
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• 1992

Bearing information of target is used critically for target tracking in underwater environment. In passive sonar, target bearing measurements are obtained by processing the acoustic signal emanating from the target. PDA tracking algorithm is usually applied in this case since bearing measurements have several peaks due to interference with other acoustic sources or reflections from underwater media. In this paper, we propose a modified PDA algorithm adopting new probabilistic distributions of the number, position, and amplitude of peaks based on the analysis of real data. This algorithm is tested on real and artificially generated data. The computer simulation result shows improvement of the tracking performance.