• The Journal of the Acoustical Society of Korea
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• v.12 no.3
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• pp.76-82
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• 1993

• Journal of KSNVE
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• v.24 no.5
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• pp.40-45
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• 2014

• The Journal of the Acoustical Society of Korea
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• v.42 no.2
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• pp.113-123
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• 2023

This paper describes the acoustical conditions of elementary school and high school classrooms as well as university classrooms in Korea and suggests a need for Korean acoustic standards and guidelines for classroom design. Current standards and guidelines of classroom acoustics in several countries were briefly introduced to understand their acoustical performance criteria for background noise levels and reverberation times, and noise isolation design requirements in various types of classrooms. The results of several acoustic survey of domestic classrooms in elementary school, high school, and university were described and compared to provide information of the acoustic characteristics of Korean school classrooms. The survey includes occupied and unoccupied data on the acoustical conditions, noise levels, and noise isolation performance in the classrooms. Acoustical parameter values for achieving 'good' speech intelligibility in active university classrooms were also presented.

• Journal of KSNVE
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• v.8 no.2
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• pp.232-238
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• 1998

선박 방사소음은 군사적 목적의 수동소나가 탐지대상으로 하는 수중음향 표적이라 할 수 있다. 따라서 수동소나 운용자는 대잠전 수행이전에 다양한 선박들에 대한 방사소음을 측정, 분석하여 개별 선박 고유의 음향 특징을 수집함으로써 실전 상황에서 미지 선박이 탐지되는 경우 이들 자료를 식별의 기초자료로 활용하고자 한다. 또한 새로운 수동소나의 개발자나 스텔스 능력의 선박 설계자 역시 선박방사소음 특징자료를 필요로한다. 본 글은 선박방사소음의 발생기구, 측정시스템 및 측정자료의 분석 평가 기술을 연구분석한 내용이다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.191-196
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• 2000

본 논문에서는 공조용 소음기에 대한 삽입손실 및 압력손실과 같은 음향성능 평가를 위해 필요한 제반 사항을 ISO 7235에 근거하여 소개하였다. 이를 위해 시험설비의 종류 및 구비조건, 측정방법, 측정시 유의사항 등을 기술하였고, 이로서 공조용 소음기의 보다 정확한 음향성능평가가 이루어지도록 검토 하였다.

• The Journal of the Acoustical Society of Korea
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• v.4 no.3
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• pp.47-52
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• 1985

한국 연안에서 높게 보고되고 있는 수중소음의 소음원을 규명하기 위하여 해상교통량 변화에 따 르는 소음 수준의 변화를 2KHz 이하에서 관측하였다. 100Hz 부근의 소음은 이미 잘 알려진대로 선박에 기인함이 실험결과에서 드러났지만, 그 수준은 100~110dB로 높게 관측되었다. 더욱이 관측선으로 부터 의 거리변화율이 심한 근거리에 다수의 선박들이 분포해 있을 때 10분 간격의 소음 변화는 특히 1KHz 이상에서 최고 10 dB까지 변화를 보였다. 이것은 연근해의 밀집해 있는 선박들이 이 주파수대에서도 하 나의 소음원으로서 작용함을 의미한다.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.31-37
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• 2021

In this paper, we design an acoustic meta-material silencer that operates at low frequency to reduce noise in duct. A high refractive index meta-material silencer is demonstrated with a combination of zigzag structured thin waveguide and helmholtz resonator, which reduces the speed of sound. Finite Element Method (FEM) analysis via thermo-viscous acoustic mesh is performed in order to calculate thermo-viscous dissipation in sub-wavelength waveguide. Sound power reflection, transmission and absorption coefficients are obtained utilizing 4-Microphone Method. The results show that cut-off frequency and transmission loss can be controlled through adjusting intervals of the zigzag structures. A wide-band acoustic silencer is also suggested by connecting meta-materials in series or parallel.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.881-890
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• 2022

As individual and group users actively use drones, the risks (Intrusion, Information leakage, and Sircraft crashes and so on) in no-fly zones are also increasing. Therefore, it is necessary to build a system that can detect drones intruding into the no-fly zone. General acoustic drone detection researches do not derive location-independent performance by directly learning drone sound including environmental noise in a deep learning model to overcome environmental noise. In this paper, we propose a drone detection system that collects sounds including environmental noise, and detects drones by removing noise from target sound. After removing environmental noise from the collected sound, the proposed system predicts the drone sound using Mel spectrogram and CNN deep learning. As a result, It is confirmed that the drone detection performance, which was weak due to unstudied environmental noises, can be improved by more than 7%.

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.105-112
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• 2020

An analysis model of noise map is proposed to evaluate and reduce the acoustical noise of power plant and its surroundings. The sound powers of many noise sources are estimated by measuring the sound levels of major equipments in the power plant. The analysis of noise has been made by using ENPro that is a commercial program for environmental noise prediction. The proposed model is verified by comparing the results from noise analysis and measurement at several points of the power plant units 1 through 4, and residential areas. It is shown that noise map simulation using the proposed model has a reliability, since the overall noise level approximates within the error of ±2 dB. Furthermore, through noise analysis, the increasing effect of noise due to newly established units 5 and 6 on residential areas is also analyzed. Consequently, the noise barrier is designed to meet an environmental noise standard and satisfy low cost and safety conditions.

• The Journal of the Acoustical Society of Korea
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• v.10 no.6
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• pp.58-63
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• 1991

선박소음이 우세한 해역에서 측정된 수중소음의 크기를 분석한 결과 100Hz 미만에서는 깊은 수 심에서의 소음 크기가 낮은 수심에서보다 크게 나타나고 있다. 한편 계절적인 소음 크기의 변화는 dam 파 전달 조건에 좌우되며, 일반적인 spectrum shape은 Urick의 선박소음이 우세한 경우의 spectrum과 매우 유사하다.