Pub Date : 2020-07-01DOI: 10.7776/ASK.2020.39.4.364
T. Park, HyunShig Joo, I. Jang, Seung-Hoon Kang, W. Ohm, Sang-Joon Shin, Jeongwon Park
Rocket noise generated from the exhaust plume produces the enormous acoustic loading, which adversely affects the integrity of the electronic components and payload (satellite) at liftoff. The prediction of rocket noise consists of two steps: the supersonic jet exhaust is simulated by a method of the Computational Fluid Dynamics (CFD), and an acoustic transport method, such as the Helmholtz-Kirchhoff integral, is applied to predict the noise field. One of the difficulties in the CFD step is to remove the boundary reflection artifacts from the finite computation boundary. In general, artificial damping, known as a sponge layer, is added nearby the boundary to attenuate these reflected waves but this layer demands a large computational area and an optimization procedure of related parameters. In this paper, a cost-efficient way to separate the reflected waves based on the two microphone method is firstly introduced and applied to the computation result of a laboratory-scale supersonic jet noise without sponge layers.
{"title":"A method for removal of reflection artifact in computational fluid dynamic simulation of supersonic jet noise","authors":"T. Park, HyunShig Joo, I. Jang, Seung-Hoon Kang, W. Ohm, Sang-Joon Shin, Jeongwon Park","doi":"10.7776/ASK.2020.39.4.364","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.4.364","url":null,"abstract":"Rocket noise generated from the exhaust plume produces the enormous acoustic loading, which adversely affects the integrity of the electronic components and payload (satellite) at liftoff. The prediction of rocket noise consists of two steps: the supersonic jet exhaust is simulated by a method of the Computational Fluid Dynamics (CFD), and an acoustic transport method, such as the Helmholtz-Kirchhoff integral, is applied to predict the noise field. One of the difficulties in the CFD step is to remove the boundary reflection artifacts from the finite computation boundary. In general, artificial damping, known as a sponge layer, is added nearby the boundary to attenuate these reflected waves but this layer demands a large computational area and an optimization procedure of related parameters. In this paper, a cost-efficient way to separate the reflected waves based on the two microphone method is firstly introduced and applied to the computation result of a laboratory-scale supersonic jet noise without sponge layers.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"364-370"},"PeriodicalIF":0.4,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46315794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.7776/ASK.2020.39.4.279
Sunhyo Kim, Seom-kyu Jung, D. Kang, Mira Kim, Sungho Cho
The study on the temporal and spatial monitoring of passing vessels is important in terms of protection and management the marine ecosystem in the coastal area. In this paper, we propose the automatic detection technique of passing vessel by utilizing an artificial intelligence technology and broadband striation patterns which are characteristic of broadband noise radiated by passing vessel. Acoustic measurements to collect underwater noise spectrum images and ship navigation information were conducted in the southern region of Jeju Island in South Korea for 12 days (2016.07.15-07.26). And the convolution neural network model is optimized through learning and validation processes based on the collected images. The automatic detection performance of passing vessel is evaluated by precision (0.936), recall (0.830), average precision (0.824), and accuracy (0.949). In conclusion, the possibility of the automatic detection technique of passing vessel is confirmed by using an artificial intelligence technology, and a future study is proposed from the results of this study.
{"title":"Application of the artificial intelligence for automatic detection of shipping noise in shallow-water","authors":"Sunhyo Kim, Seom-kyu Jung, D. Kang, Mira Kim, Sungho Cho","doi":"10.7776/ASK.2020.39.4.279","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.4.279","url":null,"abstract":"The study on the temporal and spatial monitoring of passing vessels is important in terms of protection and management the marine ecosystem in the coastal area. In this paper, we propose the automatic detection technique of passing vessel by utilizing an artificial intelligence technology and broadband striation patterns which are characteristic of broadband noise radiated by passing vessel. Acoustic measurements to collect underwater noise spectrum images and ship navigation information were conducted in the southern region of Jeju Island in South Korea for 12 days (2016.07.15-07.26). And the convolution neural network model is optimized through learning and validation processes based on the collected images. The automatic detection performance of passing vessel is evaluated by precision (0.936), recall (0.830), average precision (0.824), and accuracy (0.949). In conclusion, the possibility of the automatic detection technique of passing vessel is confirmed by using an artificial intelligence technology, and a future study is proposed from the results of this study.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"279-285"},"PeriodicalIF":0.4,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48397654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.7776/ASK.2020.39.4.263
H. Jeon, Ji-Sun Kim, Bong-Ju Kim, Won-Jin Kim
In this study, a rotating machine that can reproduce normal condition and 8 fault conditions were produced, and vibration data was acquired. Feature is calculated from the acquired data, and accuracy is analyzed through fault diagnosis using artificial neural networks and genetic algorithms. In order to achieve optimal timing and higher accuracy, features by three domains were applied to the fault diagnosis. The learning number was selected as a setting variable. As a result of the rotating machine fault diagnosis, high precision was found in the frequency domain than in others, and precise fault diagnoses were accomplished through all of 10 operations, at the learning number of 5000 and 8000. Given the efficiency of time, it was estimated to be the most efficient when the number of learning was 5000.
{"title":"A study on the fault diagnosis of rotating machine by machine learning","authors":"H. Jeon, Ji-Sun Kim, Bong-Ju Kim, Won-Jin Kim","doi":"10.7776/ASK.2020.39.4.263","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.4.263","url":null,"abstract":"In this study, a rotating machine that can reproduce normal condition and 8 fault conditions were produced, and vibration data was acquired. Feature is calculated from the acquired data, and accuracy is analyzed through fault diagnosis using artificial neural networks and genetic algorithms. In order to achieve optimal timing and higher accuracy, features by three domains were applied to the fault diagnosis. The learning number was selected as a setting variable. As a result of the rotating machine fault diagnosis, high precision was found in the frequency domain than in others, and precise fault diagnoses were accomplished through all of 10 operations, at the learning number of 5000 and 8000. Given the efficiency of time, it was estimated to be the most efficient when the number of learning was 5000.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"263-269"},"PeriodicalIF":0.4,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49443891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-01DOI: 10.7776/ASK.2020.39.4.322
Logan T Mathews, K. Gee, G. W. Hart, Reese D. Rasband, Daniel J. Novakovich, Francisco I. Irarrazabal, Aaron B. Vaughn, P. Nelson
This study investigates the far-field noise from three Falcon 9 vehicle launches from Vandenberg Air Force Base, CA, USA, as measured from the same location within the nearby community of Lompoc. The overall sound pressure levels for the three launches are shown to be similar, but some differences in the early launch period are thought to be weather-related. The peak directivity angle in overall level is approximately 65 deg, which is consistent with horizontally-fired, static rocket data. For the third launch, waveforms and spectra are analyzed for different events during the launch sequence. The measured spectral bandwidth decreases with time, but spectral levels remain above the ambient noise throughout the main-engine firing. Additionally, late-launch phenomena observed in the data appear to be correlated with main-engine cutoff and second-stage engine start.
{"title":"Comparative analysis of noise from three Falcon 9 launches","authors":"Logan T Mathews, K. Gee, G. W. Hart, Reese D. Rasband, Daniel J. Novakovich, Francisco I. Irarrazabal, Aaron B. Vaughn, P. Nelson","doi":"10.7776/ASK.2020.39.4.322","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.4.322","url":null,"abstract":"This study investigates the far-field noise from three Falcon 9 vehicle launches from Vandenberg Air Force Base, CA, USA, as measured from the same location within the nearby community of Lompoc. The overall sound pressure levels for the three launches are shown to be similar, but some differences in the early launch period are thought to be weather-related. The peak directivity angle in overall level is approximately 65 deg, which is consistent with horizontally-fired, static rocket data. For the third launch, waveforms and spectra are analyzed for different events during the launch sequence. The measured spectral bandwidth decreases with time, but spectral levels remain above the ambient noise throughout the main-engine firing. Additionally, late-launch phenomena observed in the data appear to be correlated with main-engine cutoff and second-stage engine start.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"322-330"},"PeriodicalIF":0.4,"publicationDate":"2020-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48691339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.7776/ASK.2020.39.3.151
Cheol-Soo Park, S. Jeong, Gun-Do Kim, I. Moon, G. Yim
{"title":"A study on the estimation of bubble size distribution using an acoustic inversion method","authors":"Cheol-Soo Park, S. Jeong, Gun-Do Kim, I. Moon, G. Yim","doi":"10.7776/ASK.2020.39.3.151","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.3.151","url":null,"abstract":"","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"151-162"},"PeriodicalIF":0.4,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42817993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.7776/ASK.2020.39.3.163
Euicheol Jeong, Tae-Hwan Kim
{"title":"Analysis of the range estimation error of a target in the asynchronous bistatic sonar","authors":"Euicheol Jeong, Tae-Hwan Kim","doi":"10.7776/ASK.2020.39.3.163","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.3.163","url":null,"abstract":"","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"163-169"},"PeriodicalIF":0.4,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46906280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.7776/ASK.2020.39.3.191
J. Paik, Xueyang Zhang, W. Hong, Jungpyo Hong, Seong-Il Kim, Joon-Ho Lee
Currently, studies on the estimation algorithm based on compressive sensing are actively underway, but to the best of our knowledge, no study on the performance of the Sparse Spectrum Fitting (SpSF) algorithm in nonuniform sensor arrays has been made. This paper deals with the derivation of the compressive sensing based covariance fitting algorithm extended to the frequency domain. In addition, it shows the performance of directon-of-arrival estimation of the frequency domain SpSF algorithm in non-uniform linear sensor array system and the sensor array failure situation.
{"title":"Performance of direction-of-arrival estimation of SpSF in frequency domain: in case of non-uniform sensor array","authors":"J. Paik, Xueyang Zhang, W. Hong, Jungpyo Hong, Seong-Il Kim, Joon-Ho Lee","doi":"10.7776/ASK.2020.39.3.191","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.3.191","url":null,"abstract":"Currently, studies on the estimation algorithm based on compressive sensing are actively underway, but to the best of our knowledge, no study on the performance of the Sparse Spectrum Fitting (SpSF) algorithm in nonuniform sensor arrays has been made. This paper deals with the derivation of the compressive sensing based covariance fitting algorithm extended to the frequency domain. In addition, it shows the performance of directon-of-arrival estimation of the frequency domain SpSF algorithm in non-uniform linear sensor array system and the sensor array failure situation.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"191-199"},"PeriodicalIF":0.4,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45868671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.7776/ASK.2020.39.3.170
Donghyun Roh
Cymbal transducers are often used as an array rather than single because they have a high quality factor and low energy conversion efficiency. When used as an array, there occurs a big change in the frequency characteristics of the array due to the interaction between constituent transducers. In this study, we designed the structure of a cymbal transducer array to have ultra-wideband characteristics using this property. First, cymbal transducers with specific center frequencies were designed. Then, a 2x2 planar array was constructed with the designed transducers, where the cymbal transducers were arranged to have same or opposite polarization directions. For this structure, we analyzed the effect of the difference in the center frequency of and the spacing between the constituent transducers on the acoustical characteristics of the array. Based on the analysis, we designed the structure of the cymbal transducer array to have the widest possible bandwidth.
{"title":"Design of a wideband cymbal transducer array","authors":"Donghyun Roh","doi":"10.7776/ASK.2020.39.3.170","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.3.170","url":null,"abstract":"Cymbal transducers are often used as an array rather than single because they have a high quality factor and low energy conversion efficiency. When used as an array, there occurs a big change in the frequency characteristics of the array due to the interaction between constituent transducers. In this study, we designed the structure of a cymbal transducer array to have ultra-wideband characteristics using this property. First, cymbal transducers with specific center frequencies were designed. Then, a 2x2 planar array was constructed with the designed transducers, where the cymbal transducers were arranged to have same or opposite polarization directions. For this structure, we analyzed the effect of the difference in the center frequency of and the spacing between the constituent transducers on the acoustical characteristics of the array. Based on the analysis, we designed the structure of the cymbal transducer array to have the widest possible bandwidth.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"170-178"},"PeriodicalIF":0.4,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41323875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.7776/ASK.2020.39.3.179
Myoungin Shin, Youngbin Cho, Youngmin Choo, Keunhwa Lee, Jungpyo Hong, Seongil Kim, W. Hong
In this paper, we estimated the Direction of Arrival (DOA) using Conventional BeamForming (CBF), adaptive beamforming and compressive beamforming. Minimum Variance Distortionless Response (MVDR) and Multiple Signal Classification (MUSIC) are used as the adaptive beamforming, and grid-free compressive sensing is applied for the compressive sensing beamforming. Theoretical background and limitations of each technique are introduced, and the performance of each technique is compared through simulation and real experiments. The real experiments are conducted in the presence of reflected signal, transmitting a sound using two speakers and receiving acoustic data through a linear array consisting of eight microphones. Simulation and experimental results show that the adaptive beamforming and the grid-free compressive beamforming have a higher resolution than conventional beamforming when there are uncorrelated signals. On the other hand, the performance of the adaptive beamforming is degraded by the reflected signals whereas the grid-free compressive beamforming still improves the conventional beamforming resolution regardless of reflected signal presence.
{"title":"Analysis on performance of grid-free compressive beamforming based on experiment","authors":"Myoungin Shin, Youngbin Cho, Youngmin Choo, Keunhwa Lee, Jungpyo Hong, Seongil Kim, W. Hong","doi":"10.7776/ASK.2020.39.3.179","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.3.179","url":null,"abstract":"In this paper, we estimated the Direction of Arrival (DOA) using Conventional BeamForming (CBF), adaptive beamforming and compressive beamforming. Minimum Variance Distortionless Response (MVDR) and Multiple Signal Classification (MUSIC) are used as the adaptive beamforming, and grid-free compressive sensing is applied for the compressive sensing beamforming. Theoretical background and limitations of each technique are introduced, and the performance of each technique is compared through simulation and real experiments. The real experiments are conducted in the presence of reflected signal, transmitting a sound using two speakers and receiving acoustic data through a linear array consisting of eight microphones. Simulation and experimental results show that the adaptive beamforming and the grid-free compressive beamforming have a higher resolution than conventional beamforming when there are uncorrelated signals. On the other hand, the performance of the adaptive beamforming is degraded by the reflected signals whereas the grid-free compressive beamforming still improves the conventional beamforming resolution regardless of reflected signal presence.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"179-190"},"PeriodicalIF":0.4,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41375268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-01DOI: 10.7776/ASK.2020.39.3.207
Jun Seok Kim
There are several methods for the time delay estimation between signals to two receivers. Among these methods, Generalized Cross Correlation (GCC), which estimates the relative delay from the crosscorrelation between the different signals at the two receivers, is a traditionally well-known method. However, when using a narrow band Continuous Wave (CW) signal, the GCC method degrades the estimation performance from relatively higher signal-to-noise ratio than when using a wideband signal. To improve this phenomenon, this paper examines four different pre-processors for GCC using narrow band single frequency signals. Simulation shows that the performance gain of the preprocessed GCC is up to 9 dB for a 100 msec CW signal as well as up to 4 dB for a 1 s CW signal.
{"title":"Study on the pre-processors to improve the generalized-cross -correlation based time delay estimation under the narrow band single tone signal environments","authors":"Jun Seok Kim","doi":"10.7776/ASK.2020.39.3.207","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.3.207","url":null,"abstract":"There are several methods for the time delay estimation between signals to two receivers. Among these methods, Generalized Cross Correlation (GCC), which estimates the relative delay from the crosscorrelation between the different signals at the two receivers, is a traditionally well-known method. However, when using a narrow band Continuous Wave (CW) signal, the GCC method degrades the estimation performance from relatively higher signal-to-noise ratio than when using a wideband signal. To improve this phenomenon, this paper examines four different pre-processors for GCC using narrow band single frequency signals. Simulation shows that the performance gain of the preprocessed GCC is up to 9 dB for a 100 msec CW signal as well as up to 4 dB for a 1 s CW signal.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"207-215"},"PeriodicalIF":0.4,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44602703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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