Pub Date : 2021-01-01DOI: 10.7776/ASK.2021.40.1.055
Gyunam Kim, Ga-ram Ku, C. Cheong, W. Kang, Kuksu Kim
In this study, a numerical methodology is proposed for evaluating valve flow noise in a pipe conveying high pressure gas, and the effects of perforated plates on reduction of such valve flow noise are quantitatively analyzed. First, high-accurate unsteady compressible Large Eddy Simulation techniques are utilized to predict flow and flow noise by a valve in a high-pressure pipe. The validity of the numerical result is confirmed by comparing the predicted wall pressure spectrum with the measured one. Next, the acoustic power of downstream-propagating acoustic waves due to the valve flow is analyzed using an acoustic power formula for acoustic waves propagating on mean flow in a pipe. Based on the analysis results, perforated plates are designed and installed downstream of the valve to suppress the valve flow noise and the acoustic power of downstream-going acoustic waves is predicted by using the same numerical procedure. The reduction by 9.5 dB is confirmed by comparing the predicted result with that of the existing system. Based on these results, the current numerical methodology is expected to be used to reduce valve flow noise in an existing system as well as in a design stage.
{"title":"Numerical investigation on reduction of valve flow noise in high pressure gas pipe using perforated plates","authors":"Gyunam Kim, Ga-ram Ku, C. Cheong, W. Kang, Kuksu Kim","doi":"10.7776/ASK.2021.40.1.055","DOIUrl":"https://doi.org/10.7776/ASK.2021.40.1.055","url":null,"abstract":"In this study, a numerical methodology is proposed for evaluating valve flow noise in a pipe conveying high pressure gas, and the effects of perforated plates on reduction of such valve flow noise are quantitatively analyzed. First, high-accurate unsteady compressible Large Eddy Simulation techniques are utilized to predict flow and flow noise by a valve in a high-pressure pipe. The validity of the numerical result is confirmed by comparing the predicted wall pressure spectrum with the measured one. Next, the acoustic power of downstream-propagating acoustic waves due to the valve flow is analyzed using an acoustic power formula for acoustic waves propagating on mean flow in a pipe. Based on the analysis results, perforated plates are designed and installed downstream of the valve to suppress the valve flow noise and the acoustic power of downstream-going acoustic waves is predicted by using the same numerical procedure. The reduction by 9.5 dB is confirmed by comparing the predicted result with that of the existing system. Based on these results, the current numerical methodology is expected to be used to reduce valve flow noise in an existing system as well as in a design stage.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"40 1","pages":"55-63"},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71370780","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 : 2021-01-01DOI: 10.7776/ASK.2021.40.1.038
Han Seol Jeong
: In this study, changes in cavitation pattern and noise by air injection were investigated experimentally in a cavitation tunnel. Air injection system that can control the location and the amount of air was manufactured and installed in an elliptic wing that exhibits similar characteristics to those of a propeller blade. Various types of cavitation were simulated on the hydrofoil by adjusting the test conditions in the cavitation tunnel, and the changes in cavitation pattern and noise according to air injection were experimentally analyzed. It was shown that the noise characteristics varied depending on the position and the amount of air injection. This means that in order to apply the air injection technology to the propeller, it is necessary to optimize the air injection location and the amount of injection according to the cavitation characteristics.
{"title":"Study on the cavitation and noise characteristics by air injection in three dimensional hydrofoil","authors":"Han Seol Jeong","doi":"10.7776/ASK.2021.40.1.038","DOIUrl":"https://doi.org/10.7776/ASK.2021.40.1.038","url":null,"abstract":": In this study, changes in cavitation pattern and noise by air injection were investigated experimentally in a cavitation tunnel. Air injection system that can control the location and the amount of air was manufactured and installed in an elliptic wing that exhibits similar characteristics to those of a propeller blade. Various types of cavitation were simulated on the hydrofoil by adjusting the test conditions in the cavitation tunnel, and the changes in cavitation pattern and noise according to air injection were experimentally analyzed. It was shown that the noise characteristics varied depending on the position and the amount of air injection. This means that in order to apply the air injection technology to the propeller, it is necessary to optimize the air injection location and the amount of injection according to the cavitation characteristics.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"40 1","pages":"38-45"},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71370769","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 : 2021-01-01DOI: 10.7776/ASK.2021.40.1.073
S. Kim
Wind power energy harvesting has a big potential as a future clean energy resource, but accompanies infrasonic noises. The infrasound is difficult to shield and can induce various negative physiological effects. In this study, the Wind Turbine Syndrome (WTS) caused by the infrasonic noises are introduced, and the technical aspects for the measurement and management of the infrasonic noises from wind power plants are discussed.
{"title":"Harmfulness of infrasound and wind turbine noise managements","authors":"S. Kim","doi":"10.7776/ASK.2021.40.1.073","DOIUrl":"https://doi.org/10.7776/ASK.2021.40.1.073","url":null,"abstract":"Wind power energy harvesting has a big potential as a future clean energy resource, but accompanies infrasonic noises. The infrasound is difficult to shield and can induce various negative physiological effects. In this study, the Wind Turbine Syndrome (WTS) caused by the infrasonic noises are introduced, and the technical aspects for the measurement and management of the infrasonic noises from wind power plants are discussed.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"9 1","pages":"73-83"},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71370830","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 : 2021-01-01DOI: 10.7776/ASK.2021.40.1.092
Young-il Kim
{"title":"Development of noise mapping system to manage the interior room noise of power plants","authors":"Young-il Kim","doi":"10.7776/ASK.2021.40.1.092","DOIUrl":"https://doi.org/10.7776/ASK.2021.40.1.092","url":null,"abstract":"","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"40 1","pages":"92-98"},"PeriodicalIF":0.4,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71370840","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 : 2020-11-01DOI: 10.7776/ASK.2020.39.6.505
Dongsuk Yook, Hyowon Lee, In-Chul Yoo
Since a large amount of training data is typically needed to train Deep Neural Networks (DNNs), a parallel training approach is required to train the DNNs. The Stochastic Gradient Descent (SGD) algorithm is one of the most widely used methods to train the DNNs. However, since the SGD is an inherently sequential process, it requires some sort of approximation schemes to parallelize the SGD algorithm. In this paper, we review various efforts on parallelizing the SGD algorithm, and analyze the computational overhead, communication overhead, and the effects of the approximations.
{"title":"A survey on parallel training algorithms for deep neural networks","authors":"Dongsuk Yook, Hyowon Lee, In-Chul Yoo","doi":"10.7776/ASK.2020.39.6.505","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.6.505","url":null,"abstract":"Since a large amount of training data is typically needed to train Deep Neural Networks (DNNs), a parallel training approach is required to train the DNNs. The Stochastic Gradient Descent (SGD) algorithm is one of the most widely used methods to train the DNNs. However, since the SGD is an inherently sequential process, it requires some sort of approximation schemes to parallelize the SGD algorithm. In this paper, we review various efforts on parallelizing the SGD algorithm, and analyze the computational overhead, communication overhead, and the effects of the approximations.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"505-514"},"PeriodicalIF":0.4,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41409757","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 : 2020-11-01DOI: 10.7776/ASK.2020.39.6.515
J. Choi, Seo-Yoon Ryu, C. Cheong, Tae Hoon Kim, J. Koo
{"title":"Development of high performance and low noise axial-flow fan for cooling machine room of refrigerator using airfoil-cascade analysis and surface ridge shape","authors":"J. Choi, Seo-Yoon Ryu, C. Cheong, Tae Hoon Kim, J. Koo","doi":"10.7776/ASK.2020.39.6.515","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.6.515","url":null,"abstract":"","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"515-523"},"PeriodicalIF":0.4,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43894837","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 : 2020-11-01DOI: 10.7776/ASK.2020.39.6.541
S. An
To overcome the disadvantage of hull mounted sonar, many countries operate dipping sonar system for helicopter. Although limited in performance, this system has the advantage of ensuring the survivability of the surface ship and improving the detection performance by adjusting the depth according to the ocean environment. In this paper, a method to calculate the optimal depth of the dipping sonar for helicopters is proposed by applying an optimization algorithm. In addition, in order to evaluate the performance of the sonar, the Sonar Performance Function (SPF) is defined to consider the ocean environment, the depth of the target and the depth of the dipping sonar. In order to reduce the calculation time, the optimal depth is calculated by applying Simulated Annealing (SA), one of the optimization algorithms. For the verification of accuracy, the optimal depth calculated by applying the optimization technique is compared with the calculation of the SPF. This paper also provides the results of calculation of optimal depth for ocean environment in the East sea.
{"title":"Optimal depth for dipping sonar system using optimization algorithm","authors":"S. An","doi":"10.7776/ASK.2020.39.6.541","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.6.541","url":null,"abstract":"To overcome the disadvantage of hull mounted sonar, many countries operate dipping sonar system for helicopter. Although limited in performance, this system has the advantage of ensuring the survivability of the surface ship and improving the detection performance by adjusting the depth according to the ocean environment. In this paper, a method to calculate the optimal depth of the dipping sonar for helicopters is proposed by applying an optimization algorithm. In addition, in order to evaluate the performance of the sonar, the Sonar Performance Function (SPF) is defined to consider the ocean environment, the depth of the target and the depth of the dipping sonar. In order to reduce the calculation time, the optimal depth is calculated by applying Simulated Annealing (SA), one of the optimization algorithms. For the verification of accuracy, the optimal depth calculated by applying the optimization technique is compared with the calculation of the SPF. This paper also provides the results of calculation of optimal depth for ocean environment in the East sea.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"541-548"},"PeriodicalIF":0.4,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49586221","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 : 2020-11-01DOI: 10.7776/ASK.2020.39.6.549
Seong-Weon Kim, Hyeon‑Deok Cho, Taek-ik Kwon
{"title":"A study on the improvement of robust automatic initiated tracking on narrowband target","authors":"Seong-Weon Kim, Hyeon‑Deok Cho, Taek-ik Kwon","doi":"10.7776/ASK.2020.39.6.549","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.6.549","url":null,"abstract":"","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"549-558"},"PeriodicalIF":0.4,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45035760","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 : 2020-11-01DOI: 10.7776/ASK.2020.39.6.592
Bonhwa Ku, Gwantae Kim, Su Jang, Hanseok Ko
This paper proposes a Convolutional Recurrent Neural Net (CRNN) structure that can simultaneously reflect both static and dynamic characteristics of seismic waveforms for various earthquake events classification. Addressing various earthquake events, including not only micro-earthquakes and artificial-earthquakes but also macro-earthquakes, requires both effective feature extraction and a classifier that can discriminate seismic waveform under noisy environment. First, we extract the static characteristics of seismic waveform through an attention-based convolution layer. Then, the extracted feature-map is sequentially injected as input to a multiinput single-output Long Short-Term Memory (LSTM) network structure to extract the dynamic characteristic for various seismic event classifications. Subsequently, we perform earthquake events classification through two fully connected layers and softmax function. Representative experimental results using domestic and foreign earthquake database show that the proposed model provides an effective structure for various earthquake events classification.
{"title":"Earthquake events classification using convolutional recurrent neural network","authors":"Bonhwa Ku, Gwantae Kim, Su Jang, Hanseok Ko","doi":"10.7776/ASK.2020.39.6.592","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.6.592","url":null,"abstract":"This paper proposes a Convolutional Recurrent Neural Net (CRNN) structure that can simultaneously reflect both static and dynamic characteristics of seismic waveforms for various earthquake events classification. Addressing various earthquake events, including not only micro-earthquakes and artificial-earthquakes but also macro-earthquakes, requires both effective feature extraction and a classifier that can discriminate seismic waveform under noisy environment. First, we extract the static characteristics of seismic waveform through an attention-based convolution layer. Then, the extracted feature-map is sequentially injected as input to a multiinput single-output Long Short-Term Memory (LSTM) network structure to extract the dynamic characteristic for various seismic event classifications. Subsequently, we perform earthquake events classification through two fully connected layers and softmax function. Representative experimental results using domestic and foreign earthquake database show that the proposed model provides an effective structure for various earthquake events classification.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"592-599"},"PeriodicalIF":0.4,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44203084","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 : 2020-11-01DOI: 10.7776/ASK.2020.39.6.585
Jiwon Kim
The adaptive transmission techniques are efficient method for underwater acoustic communication to improve the system efficiency by varying transmission parameters according to channel conditions. In this paper, we construct four transmission modes with different data rates using the convolutional codes, which is freely set to size of information bits. On the receiver side, one critical component of adaptive system is to find which mode has best performance. In this paper, we proposed threshold detection algorithm to decide appropriate mode and applied turbo equalization method based on BCJR decoder in order to improve performance. We analyzed the performance of four modes based on threshold detection algorithm through the lake experiment.
{"title":"A study on threshold detection algorithm for adaptive transmission in underwater acoustic communication","authors":"Jiwon Kim","doi":"10.7776/ASK.2020.39.6.585","DOIUrl":"https://doi.org/10.7776/ASK.2020.39.6.585","url":null,"abstract":"The adaptive transmission techniques are efficient method for underwater acoustic communication to improve the system efficiency by varying transmission parameters according to channel conditions. In this paper, we construct four transmission modes with different data rates using the convolutional codes, which is freely set to size of information bits. On the receiver side, one critical component of adaptive system is to find which mode has best performance. In this paper, we proposed threshold detection algorithm to decide appropriate mode and applied turbo equalization method based on BCJR decoder in order to improve performance. We analyzed the performance of four modes based on threshold detection algorithm through the lake experiment.","PeriodicalId":42689,"journal":{"name":"Journal of the Acoustical Society of Korea","volume":"39 1","pages":"585-591"},"PeriodicalIF":0.4,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45695088","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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