• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.294-301
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• 2003

We examine a problem in which porous/viscoelastic compliant thin plates are subject to pressure fluctuations under transitional or turbulent boundary layer. Measurements are presented of the frequency spectra of the near-field pressure and radiated sound by compliant surface. A porous plate consisting of 5mm thick. open-cell foam with fabric covering and a viscoelastic-painted plate of 1mm thick over an acoustic board of 4mm thick were placed over a rigid surface in an anechoic wind tunnel. Streamwise velocity and wall pressure measurements were shown to highly attenuate the convective wall pressure energy when the convective wavenumber (k$_{c}$h) was 3.0 or more. The sound source localization on the compliant walls is applied to the measurement of radiated sound by using an acoustic mirror system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.640-644
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• 2003

There are many difficulties to get the scattered field generated by obstacle which has arbitrary shape or irregular surface impedance by using analytic solution or numerical methods. In this study, we propose experimental method of acoustic scattering holography that can predict the far-field scattered field based on nearfield measurements. In particular we can get the scattered fields of each wave-number components of incident fields. We express the relationship of wave-number components between incident fields and scattered fields using scattering matrix which is transfer matrix of wave-number components. Lastly, we prove the relation between wave-number components of incident and scattered field by experiments. The errors which are caused by measurements and decomposition methods are also analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1347-1352
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• 2001

In this study, the acoustic properties of polyester sound absorbing materials with three different bulk densities were investigated by calculating and measuring the acoustic parameters in terms of characteristic impedance, propagation constant, and absorption coefficient. For the calculations, Delany and Bazley's empirical equation was used together with the experimentally obtained specific flow resistivities under steady flow conditions. For the experimental measurements, the well-known two-thickness method was accessed. The experimentally measured values of characteristic impedance and propagation constant were generally agreed well with the corresponding calculated values. Based on the comparisons between the calculations and measurements, it was found that the magnitude of the absorption coefficient was closely related to the characteristic impedance and the real part of the propagation constant. Especially, the maximum magnitude of the absorption coefficient was depended upon the imaginary part of the propagation constant indicating the phase change of the propagation constant.

• The Journal of the Acoustical Society of Korea
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• v.33 no.4
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• pp.225-231
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• 2014

This paper suggests an algorithm to improve the tracking performance for an underwater acoustic target using the feedback information of acoustic feature of a target. While conventional tracking algorithms use detected acoustic signals only, the proposed algorithm uses detected acoustic signals and target feature information as well. Since the proposed algorithm tracks only the selected measurements using target feature information, it prevents onset of unnecessary tracks and improves tracking performance for target of interest. Furthermore, it optimizes tracking parameters for the target of interest and guarantees robustness and consistency of the track. Some simulations are performed to demonstrate the improved tracking performance of the proposed algorithm.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.2
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• pp.203-208
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• 2016

This paper presents a fault detection and data processing algorithm for acoustic sensor systems using the multiple sensor algorithm that has originally developed for the wireless sensor nodes. The multiple sensor algorithm can increase the reliability of the sensor systems by utilizing and comparing the measurements of the multiple sensors. In the acoustic sensor system, the equivalent sound level($L_{eq}$) is used to detect the faulty sensor. The experiment was conducted to demonstrate the feasibility of the multiple acoustic sensor algorithm, and the results show that the algorithm can detect the faulty sensor and validate the data.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.876-882
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• 2014

This study investigates an efficient method to estimate the total acoustic radiation power of submerged circular cylindrical structures. Since the acoustic radiation power of submerged vehicles can be changed during the operation, the estimation for its monitoring onboard is required to accomplish the missions. The total acoustic radiation power is estimated using the measured velocity and the calculated radiation efficiency of the surface which consists of submerged rectangular plate elements. Experiments are carried out to validate the estimation approach. Comparisons of the estimation results with the measurements show that they are in a good agreement for the mid-high frequency range and match well for the cases of different excitation locations which correspond to the different operation modes of underwater vehicles as well. Therefore, this estimation method can be applied effectively to the development of the radiated noise monitoring-system.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.167-172
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• 2011

The purpose of this study was to examine the relationship between subjective and objective evaluation in speakers with voice disorders. Subjective evaluation indicates the self-reports of voice problems by dysphonic speakers. The relating protocol is the Voice Handicap Index (VHI) and the self-awareness index of voice problems (SAIVP-14). A total of 48 individuals with voice disorders replied to the questionnaire and participated in a voice assessment. Objective evaluations included the perceptual judgement of G grade in GRBAS, acoustic measurements (jitter, shimmer, NHR) by MDVP (CSL 4400), and aerodynamic measurements (MPT, MFR, psub) by PAS (Phonatory Aerodynamic System, KayPentax, USA). Pearson and Spearman correlations were used for the analysis. In the correlation with perceptual judgement (G grade) and VHI-Total, VHI-Physical, and SAIVP-14, there was a significant correlation, but the overall correlation was poor. NHR, jitter, and shimmer were significantly correlated with overall VHI and SAIVP-14. Specifically, the correlation with shimmer was stronger compared to the other measurements. In aerodynamic measures, MFR and MPT showed a significant correlation with VHI-Total, VHI-Emotional, and SAIVP-14, but their correlation was poor. The results of this study suggested that subjective evaluation of self voice problems is meaningfully correlated with objective evaluations, but more data in the multidimensional voice assessment should be collected and analyzed for the reliability and validity of the voice handicap questionnaire.

• Journal of KSNVE
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• v.6 no.5
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• pp.645-652
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• 1996

In this paper an identification method is presented to obtain the equivalent electric circuit model of a wideband underwater acoustic piezoelectric vibrator. Unknown parameters involved in the equivalent circuit are indentified using the measured electrical admittances in air. The proposed method is applied to an example transducer. The validity of equivalent circuit model is demonstrated by the comparison between the experimental measurements and analytical calculations of TVR(transmitting voltage response) in water.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.26 no.1
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• pp.40-45
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• 2015

Objectives:This study aims to investigate the correlation between the measurements of Praat as an acoustic evaluation and those of GRBAS and CAPE-V as perceptual rating tool respectively. Through this, it also tries to find out parameters to which attention should be paid when an evaluator, who is untrained in auditory-perceptual voice evaluation, conducts voice evaluation with objective tool. Materials and Methods:Voice samples of this study were 33 vocal polyp patients(23 males and 10 females) who visited our Department of Otorhinolaryngology. They sustained vowel voices of 'e' were recorded and acoustically analyzed. Results:As the results of correlation analysis between GRBAS and Praat measurements, G scale and R scale showed statistically significant correlation with Jitt, Shim and NHR. And it is found that B scale represented significant correlation with Jitt, S scale with Shim. As the results of analysis on correlation with CAPE-V and Praat measurements, OS scale and R scale showed statistically significant correlation with Jitt, Shim and NHR. B scale represented significant correlation with Jitt, S scale with Shim. Conclusion:Although, both GRBAS and CAPE-V were highly reliable, in comparison between CAPE-V and Pratt, more parameters that showed statistically significant correlation are observed, which implies that VAS has more potential to make detailed evaluation than ORD.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.201-210
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• 2015

Repeated measurements on each variables of interest often arise in bioscience or medical research. We need to account for correlations among repeated measurements to assess the correlation between two variables in the presence of replication. This paper reviews methods to estimate a correlation coefficient between two variables in repeated measurements using the variance-covariance matrix of linear mixed effect models. We analyze acoustic radiation force impulse imaging (ARFI) data to assess correlation between three shear wave velocity (SWV) measurements in liver or spleen and spleen length by ultrasonography. We present how to obtain parameter estimates for the variance-covariance matrix and correlations in mixed effects models using PROC MIXED in SAS.