• Title/Summary/Keyword: 음향 환경 시험

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Study on Improving the Facilities of Power-Driven Water Leisure Crafts for the Deaf (청각장애인을 위한 동력수상레저기구 운영 개선방안에 관한 연구)

  • Won-Sam Choi;Bong-Kyu Jung;Cheor-Hong Park;Nam-U Lee
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.7
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    • pp.836-842
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    • 2023
  • Under the Welfare of Disabled Persons Act, the national qualification test allows disabled and non-disabled people to appear for the same test, and the deaf do not fall under the reason for disqualification from obtaining a license for power-driven water leisure crafts; therefore, even the deaf can obtain a license. During a risk of collision at sea, ships and power-driven water leisure crafts notify the other party of dangerous signals such as maneuvering and warning signals through sound signals to prevent accidents that may occur because surrounding ships are not visible. However, a method is required to prevent marine accidents that may occur when the deaf cannot hear danger signals through sounds from nearby ships or power-driven water leisure crafts during leisure activities owing to hearing impairment. A sound reception system is a device installed on a ship where missionary work is completely deposed to display the amplification of external sounds and the direction of sound reception on the screen. Through visual display of sound signals such as dangerous signals that cannot be heard owing to hearing impairment, improvement measures were proposed to prevent marine accidents that can occur owing to the inability of the deaf to check sound signals during leisure activities.

A Development of Robust Underwater Sound Signal Recognition Algorithm for Acoustic Releaser (Acoustic releaser 제어를 위한 강인한 수중음향신호 인식 알고리즘의 개발)

  • 김영진;허경무
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.41 no.3
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    • pp.33-38
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    • 2004
  • In this paper we presents a underwater sound recognition algorithm by which we can identify the sound signal without the influence of disturbances due to underwater environmental changes. The proposed method provides a means suitable for acoustic releaser which require low power dissipation and long-time underwater operation. We demonstrate its ability of securing stability and fast sound recognition through both numerical and experimental methods.

Acoustic Characteristics of Underwater Noise from Uldolmok Tidal Current Pilot Power Plant (울돌목 시험조류발전소의 수중소음 특성 연구)

  • Ko, Myungkwon;Choi, Jee Woong;Yi, Jin-Hak;Jeong, Weonmu
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.8
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    • pp.523-531
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    • 2012
  • Recently, as a result of increasing concern about eco-friendly power, the demand for the power stations using environmentally friendly powers such as photovoltaic energy, wind force, tidal power, and tidal current has been increasing worldwide. Among these power stations tidal current power plant requires strong current generated by the topographic characteristics of the ocean floor. Uldolmok waterway producing very strong current is an ideal location for a tidal current power generation. However the occurrence of anthropogenic underwater noise generated by the tidal current power station may affect the marine environment. Therefore, it is necessary to evaluate the noise radiated from the station and predict the range influenced by the radiated noise. In this paper, the measurements of radiated noise spectrum level by the tidal current power station are presented, and the source level per unit area is estimated. Finally, the propagation properties of the radiated noise in the Uldolmok waterway is evaluated from the model simulation using the parabolic equation method, RAM.

Simulation of underwater reverberation signals (수중 잔향음 신호 모의)

  • Oh, Sun-Taek;Na, Jung-Yul
    • The Journal of the Acoustical Society of Korea
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    • v.13 no.6
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    • pp.66-74
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    • 1994
  • Simulation of sonar reverberation time series is very useful because most acoustic models are power level models and have a difficulty when performance of hardware system is evaluated under the reverberant condition. Thus, in this paper, the simulation of reverberation time series is attempted, First, normalized spectrum, whose bandwidth is varying in the frequency domain and which has zero-mean Gaussian distribution, is calculated at pre-selected receiving time. Second, reverberation levels given by underwater acoustic model are combined with normalized spectrum in the frequency domain. Finally, nonstationary sonar reverberation time series are simulated by IFT(Inverse Fourier Transform).

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The Implementation of a Real-time Underwater Acoustic Communication System at Shallow water (천해역에서의 실시간 수중 데이터 통신 시스템 구현)

  • Baek, Hyuk;Park, Jong-Won;Lim, Yong-Kon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.06a
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    • pp.754-757
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    • 2007
  • In this paper, we present an implementation and it's real-sea test of an underwater acoustic data communication system, which allows the system to reduce complexity and increase robustness in time variant underwater environments. For easy adaptation to complicated and time-varying environments of the ocean, all-digital transmitter and receiver systems were implemented. For frame synchronization the CAZAC sequence was used, and QPSK modulation/ demodulation method with carrier frequency of 25kHz and a bandwidth of 5kHz were applied to generate 10kbps transmission rate including overhead. To improve transmission quality, we used several techniques and algorithms such as adaptive beamforming, adaptive equalizer, and convolution coding/Viterbi decoding. for the verification of the system performance, measurement of BER has been done in a very shallow water with depth of 8m at JangMok, Geoje. During the experiment, image data were successfully transmitted up to about 7.4km.

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A Study on the Path Loss of Underwater Acoustic Channel Based on At-sea Experiment at the South Sea of Korea (남해 실해역 시험 기반 수중음향채널 경로손실에 관한 연구)

  • Kim, Min-Sang;Lee, Tae-Seok;Cho, Yong-Ho;Im, Tae-Ho;Ko, Hak-Lim
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.24 no.3
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    • pp.405-411
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    • 2020
  • Recently, studies on underwater communication, related to the development of underwater resources, disaster monitoring and defense, have been actively carried out. In the design of wireless communication systems, path loss is the most important information to derive a link budget that is required to guarantee communication reliability by calculating received power level for the given communication link. The underwater acoustic channel have different characteristics according to geographical location and relevant environmental factors such as water temperature, depth, wave height, algae, and turbidity. Subsequently, many research institutes aiming to develop underwater acoustic communication systems are researching actively on the underwater acoustic channels in various sea areas. In Korea, however, studies on the path loss of the acoustic channel are still insufficient. Therefore, in this study, the path loss of the acoustic channel are studied based on measurement data of the at-sea experiment conducted at Geohae-do, southern sea of Korea.

Higher Order Parabolic Equation Modeling Using Galerkin's Method (Galerkin방법을 이용한 고차 포물선 방정식 수중음 전달 해석)

  • 이철원;성우제;정문섭
    • The Journal of the Acoustical Society of Korea
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    • v.18 no.4
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    • pp.71-77
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    • 1999
  • Exact forward modeling of acoustic propagation is crucial in MFP such as inverse problems and various other acoustic applications. As acoustic propagation in shallow water environments become important, range dependent modeling has to be considered of which PE method is considered as one of the most accurate and relatively fast. In this paper higher order numerical rode employing the PE method is developed. To approximate the depth directional operator, Galerkin's method is used with partial collocation to lessen necessary calculations. Linearization of tile depth directional operator is achieved via expansion into a multiplication form of (equation omitted) approximation. To approximate the range directional equation, Crank-Nicolson's method is used. Final1y, numerical self stater is employed. Numerical tests are performed for various occan environment scenarios. The results of these tests are compared to exact solutions, OASES and RAM results.

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Genetic Algorithm for Speaker Adaptation in Speech Recognition (유전자 알고리듬을 이용한 화자 적응적 음성인식)

  • 임동철
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1998.06c
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    • pp.107-110
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    • 1998
  • 본 논문은 DTW(Dynamic Time Warping)을 이용한 음성인식에서 표준패턴(reference patterns)으로 사용되는 벡터열을 GA(Genetic Algorithm)을 이용하여 보다 적응된 패턴의 벡터열로 생성하는 방법을 제시한다. 본 논문의 필요성은 다음과 같다. 음성인식의 주요한 엔진들 중에 하나로 DTW가 사용된다[1]. DTW는 표준패턴과 시험패턴(test patterns)간의 최적 경로(optimal path)를 찾아내어 가장 유사한 패턴을 찾아내는 방법을 말한다. 그러나 음성은 같은 발음에 대해서도 사람의 발성 길이와 목의 상태 등에 따라 다양한 패턴으로 나타나며 동일 화자의 같은 어휘도 시간과 환경에 따라 변한다. 따라서 이러한 음성의 동적 특성에 적응하는 방법이 필요하다. 본 논문은 이러한 문제에 대한 해결 방법으로 GA를 이용하여 보다 적합하고 적응적인 표준 패턴을 생성시켜 적응하는 방법을 개발하였다.

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Comparison of acoustics performance measurement and evaluation standard of office space and office acoustics criteria of European countries (사무공간의 음향성능 측정, 평가 방법의 표준화와 유럽 국가들의 음향성능 기준 비교)

  • Jeong-Ho Jeong
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.2
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    • pp.133-142
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    • 2023
  • The office environment is changing according to work types, Information Technology (IT) advancements, and the Coronavirus disease (COVID)-19 situation. In order for office space users to perform their tasks comfortably and efficiently, it is necessary to secure individual privacy as well as easy communication among members. In Korea, the demand for improving the acoustic performance of office spaces is also increasing, but the related performance criteria and guidelines have not been established. In this study, standardization of office space acoustic performance measurement and evaluation methods and European countries' acoustic performance criteria were compared and reviewed. It is proposed to comprehensively review international standardization trends and acoustic performance standards in each country and to establish and utilize criteria for evaluating the acoustic performance and satisfaction of office spaces in Korea through our survey. Considering the international standardization direction and compatibility with communication and Public Address (PA) systems, it is appropriate to establish criteria using the speech transmission index or Speech Transmission Index (STI) application index. This criterion will be highly utilizable and compatible. In addition, since the office furniture industry is interested in improving the acoustic performance of office space, it is necessary to establish a labelling system for speech level reduction of office furniture.

Analysis of Sine Test Results with Prediction for Geo-stationary Satellite (정지궤도 위성의 정현파 가진 시험과 예측 비교)

  • Kim, Chang-Ho;Kim, Kyung-Won;Kim, Sun-Won;Lim, Jae-Hyuk;Hwang, Do-Soon
    • Journal of Satellite, Information and Communications
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    • v.5 no.1
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    • pp.80-84
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    • 2010
  • Satellite structure should be designed to accommodate and support safely the payload and equipments necessary for its own missions and to secure satellite and payloads from severe laucnch enviroments. The lauch environments imposed on satellites are quasi-static accelerations, aerodynamic loads, acoustic loads and shock loads. To qualify the structure design against low-frequency dyanmic enviromnent, sine vibration test should be performed. During sine vibration test, the notchings are implemented in order to keep the payloads and equipments from excessive loading at their own main modes. This paper deals with sine test prediction, sine vibration test results, comparison of predicted values and tested values, and verification of Finite Element Model.