• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.60-65
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• 2007

Acoustic chamber was developed for verifying the performance of a satellite under the launch condition on the Space environment test department. As the size of a satellite is increased the extension of existing facility is required. This paper encompasses the following items; redesign of components in acoustic chamber, product procedures of them and review of the test for the components of satellite in the upgraded acoustic chamber.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.66-75
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• 2003

A high intensity acoustic test facility has been constructed at Korea Aerospace Research Institute (KARI). Spacecrafts are tested in the facility to check the reliability on acoustic environment of launch vehicles. The reverberant chamber of the facility has a volume of 1,228 cubic meters and provides an acoustic environment of 152 dB over the frequency range of 25 Hz to 10,000 Hz. This paper describes how the basic parameters of the facility including a chamber and power generation system are designed. Moreover, design parameters including acoustic spectrum, acoustic modulator characteristics, reverberation time and isolation characteristics are experimentally verified during acceptance tests.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.164-167
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• 2009

The amount of acoustic data gathered from the acoustic data gathering system is increased dramatically as the acoustic data gathering system become various and highly effective. It is needed to transmit this acoustic data to analysis environment for precise analysis. In this gathering/analysis system, it is also needed the stable transmitting as well as highly perfect security. In this paper, I would like to propose a transmitting and management system sending a massive gathering acoustic data in the unsecurity and low speed networking environment. The implemented system is to transmit the acoustic data safely in low speed networking environment and secure the acoustic data from various threats.

• Korean Journal of Environment and Ecology
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• v.38 no.4
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• pp.405-415
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• 2024

The bioacoustics generated in urban parks contribute to the overall sound diversity of a city, creating a harmonious acoustic environment and maintaining the balance of the soundscape. However, due to the rapid urbanization process, the acoustic environment in urban parks is continuously deteriorating due to increased noise. In this study, we present an approach to monitoring the acoustic environment of urban parks by analyzing the soundscape of Namsan Urban Natural Park in Seoul. Acoustic data were collected continuously for one month from August 2021 in four facility districts of the study site using autonomous recording units, and a total of 2,784 hours of sound material were obtained. We also compared soundscape characteristics over time in each district using acoustic indices (ACI, ADI, BI, NDSI) representing soundscape complexity, acoustic diversity, degree of bioacoustics, and anthropogenic disturbance. The results showed that acoustic indices related to bioacoustics varied between districts, but most indices showed similar variation patterns due to the influence of anthropogenic sounds. In particular, regional differences closed during periods of high bird activity but not during periods of high human activity. We suggest that considering both acoustic characteristics and multiple acoustic indices is necessary for managing the soundscape of urban parks. The results of this study are expected to provide essential data for assessing the health of urban ecosystems based on soundscapes and to be used for monitoring the acoustic environment of urban parks.

• The Journal of Sustainable Design and Educational Environment Research
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• v.19 no.2
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• pp.21-31
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• 2020

The purpose of this study was to analyze the contents of the sound environment among the various environmental factors that directly or indirectly affect the quality of education through the remodeling of the small hall of the College of Humanities at W University. Before remodeling into a lecture room, the small hall of the College of Humanities at W University, which is the subject of this study, was designed to create an indoor sound environment suitable for a lecture room by recognizing differences in acoustic performance between the performance halls that require adequate sound quality and the lecture rooms where the clarity of voice is important. Therefore, this study aimed to present examples of improved acoustic performance in lecture rooms by remodeling through the stages of measuring acoustic performance before remodeling, presentation of a change in finishing materials through sound simulation, and measurement of sound performance after remodeling. It is expected that this process can be used as an example of securing indoor acoustic performance suitable for educational space, such as lecture rooms, by changing the finishing materials.

• The Journal of the Acoustical Society of Korea
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• v.18 no.6
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• pp.17-30
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• 1999

This paper proposes a new stereophonic acoustic echo canceller to prevent impairments on the voice quality and to remove acoustic echo effectively appearing in stereo environment at the instant of abrupt change of the transmission room environment in teleconferencing system. In stereophonic acoustic echo canceller, the major defective problems are the large computational complexity of estimating echo path systems due to the long impulse response of the true echo paths and the performance degradation of echo canceller due to large correlation between dual stereo signals. Moreover, the change of the suboptimal solution for the echo canceller was considered as a critical deficient factor on to the performance of stereophonic echo canceller. To overcome these problems, this paper proposes pseudo stereophonic acoustic echo canceller using Hyper-plane projection algorithm, which shows the robustness to the environment change of the transmission room and the efficiency of computational complexity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1323-1330
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• 2010

The amount of acoustic data gathered from the acoustic data gathering system is increased dramatically as the acoustic data gathering system become various and highly effective. It is needed to transmit this acoustic data to analysis environment for precise analysis. In this gathering/analysis system, it is also needed the stable transmitting as well as highly perfect security. But the existing system using the conveying method needs a lot of time. In case of using networks, the low speed networking vulnerable in the stable transmitting and the information security is impossible to materialize. In this paper, I would like to propose a transmitting and management system sending a massive gathering acoustic data in the unsecurity and low speed networking environment. The implemented system is to transmit the acoustic data safely in low speed networking environment and secure the acoustic data from various threats.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.873-876
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• 2011

In this research, a Helmholtz resonator was applied to the thermo-acoustic environment that has thermal gradient using Rijke tube. The thermo-acoustic instability was invoked by a Rijke tube which use a DC power supplier and a Blower. A target instability frequency was appeared by the Rijke tube. A preliminary experiment on damping characteristics of the resonator in the thermo-acoustic environment was performed and compared with the room temperature experiment data.

• The Journal of Sustainable Design and Educational Environment Research
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• v.19 no.4
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• pp.40-49
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• 2020

Recently, the form of education has changed from one-way to two-way and mutual exchange rather than the existing one-way order form, and accordingly, it is necessary to consider creating a suitable learning environment for each type of education. The basic form of education consists of the delivery of knowledge, that is, the delivery of knowledge by teachers to education consumers through voice delivery, so the sound environment is considered an essential factor in creating a pleasant learning environment. The indoor sound environment is very closely related to the mental stress of the inmate, so the quality level of education will also change greatly depending on whether or not the appropriate sound environment is created. However, the importance of the sound environment in educational facilities such as classrooms has not been highlighted due to the lack of research and related laws on the sound environment. Therefore, in this study, auditory tests were conducted using the auralization based on the physical acoustic performance data presented in the preceding study. Through this, we wanted to verify the validity of this research by analyzing the subjective acoustic performance satisfaction of the occupants due to the improvement of the physical acoustic performance. Based on these research results, it is estimated that the improvement of the sound environment of educational facilities through remodeling in the future will be possible to verify whether the sound environment suitable for educational facilities is created only after the analysis stage on the improvement of subjective sound performance as well as physical sound performance.

• The Journal of the Acoustical Society of Korea
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• v.22 no.7
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• pp.573-578
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• 2003

Recently, speaker localizing estimation technique has been rising in teleconference systems. In this paper, it was described to be able to enhance the speech quality through microphone array, and received the only signal of speaker. Unfortunately, as it using estimated the signal in advance, it is not matched in a real acoustic environment so it has poor performance. In this paper is proposed for Adaptive Matched Filter Microphone Array that estimated acoustic room environment from the received the signal and study of the efficiency through simulations.