• The Journal of the Acoustical Society of Korea
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• v.20 no.7
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• pp.3-12
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• 2001

It is known that the roughness is one of the most important metrics in assessing the sound quality. In this study, a new roughness model is suggested by combing the previous auditory filter model and several signal processing methods for the enhancement of calculation efficiency and accuracy. For testing the usefulness of the present model, the predicted responses are compared with the experimental data and it is observed that they are in good agreements. Also, it is found that the previous models have limitations to search frequency components mainly contributed to overall roughness. By modifying the correlation criteria of the present model, the revised model for the proper estimation of roughness-contributed components is embedded.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.606-611
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• 2000

It has been noted that the low frequency absorption coefficient of a porous sample placed in a standing wave tube is affected by the nature of the sample's edge constraint. The edge constraint has the effect of stiffening the solid phase of the sample, which itself can be strongly coupled to the material's fluid phase, and hence the incident sound field, by viscous means at low frequencies. In recent work it has also been shown that such a circumferential constraint causes the low frequency transmission loss of a layer of fibrous material to approach a finite low frequency limit that is proportional to the flow resistance of the layer and which is substantially higher than that of an unconstrained sample of the same material. However, it was also found that the benefit of the circumferential edge constraint was reduced in a transitional frequency range by a shearing resonance of the sample. Here it will be shown that the effect of that resonance can be mitigated or eliminated by adding additional axial and radial constraints running through the sample. It will also be shown that the constraint effect can be modeled closely by using a finite element procedure based on the Biot poroelastic theory. Implications for low frequency barrier design are also discussed.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.62-66
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• 2006

In this work, the properties of environmentally friendly functional panel made from waste aluminum were investigated. Product quality enhancement was pursued through an improved viscosity process, a mixing process by agitating, a foaming process, a cooling process, and a color addition process. An acoustic transmission attenuation test, a sound adsorption rate measurement test, and a foaming condition and scrap mixing test were implemented. As a result, the functional panel made from waste aluminum was ultra lightweight and had excellent properties such as soundproof, sound interception, and shielding harmful electromagnetic waves. Also, the functional panel showed low thermal conductivity (about 2.2 kcal/mh) and excellent heat-insulating property.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.241-242
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• 2006

MPEG Surround is an audio coding technology that represents multi-channel audio signal with downmixed audio signal(s) and very low bitrate side information based on Binaural Cue Coding. The side information consists of Inter-Channel Level Difference, Inter-Channel Correlation, and payloads. These two parameters are correspondent to the well-known spatial parameters in psycho-acoustics, Inter-aural Level Difference (ILD) and Inter-Aural Cross Correlation (IACC). Though ICLD is to provide perceptually equivalent ILD to the listener, however, the ILD of the original multi-channel audio signal and that of the MPEG Surround encoded signal was different. The difference between two ILD values is defined as ILD Distortion (ILDD). This paper provides how ILDD can be applied to enhance sound quality in MPEG Surround and how much ILDD is decreased.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.377-380
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• 2002

Acoustic Characteristics of Nitrile Butadiene Rubber with Carbon Black ContentAcoustic and mechanical properties of Nitrile Butadiene Rubbers (NBR) with the variation of the carbon black content were investigated. NBR where the acrylonitrile content is $33\%$ based on the mole percent has been prepared with fixed sulfur content for vulcanization. Acoustic measurement of the prepared rubbers were peformed in the frequency region of $300\;\~\;1000\;kHz$. Their mechanical properties such as density, hardness were also measured. Increase of the carbon black content in the rubber resulted in enhancement of the mechanical property and linear increase of the sound speed as function of the carbon black content. Interestingly, attenuation of the sound speed was only affected by the existence of the carbon black and not by the amount of carbon black in the experiment range of this article. In this study, it was found that the amount of carbon black content in the NBR was correlated with the acoustic properties and can be estimated nondestructively by the measurement of the specific acoustic property.

• Phonetics and Speech Sciences
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• v.16 no.1
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• pp.17-24
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• 2024

The Korean three-way stop contrast (lenis, aspirated, fortis) is currently undergoing a sound change, such that the primary cue distinguishing lenis and aspirated stops is shifting from voice onset time (VOT) to F0. Despite recent discussions of this shift, research on voice quality, traditionally considered an additional cue signaling the contrast, remains sparse. This study investigated the extent to which the associated voice quality [as reflected in the acoustic measurements of H1^*-H2^*, H1^*- A1^*, and cepstral peak prominence (CPP)] contributes to the three-way stop contrast, and how the realization is conditioned by prominence- vs. boundary-induced prosodic strengthening amid the ongoing sound change. Results for 12 native Korean speakers indicate that there was a substantial distinction in voice quality among the three stop categories with the breathiness of the vowel being the greatest after the lenis, intermediate after the aspirated, and least after the fortis stops, indicating the role of voice quality in the maintenance of the three-way stop contrast. Furthermore, prosodic strengthening has different effects on the contrast and contributes to the enhancement of the phonological contrast contingent on whether it is induced by prominence or boundary.

• The Mathematical Education
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• v.41 no.1
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• pp.19-34
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• 2002

The 7th national mathematics curriculum lays emphasis on an interrelation of several subjects and a connection between mathematics and real life. In this reason, this study focuses on the enhancement of sound understanding nuclear energy which is one of important factor(concepts or contents) dealt with in the other subjects such as science, environment, social studies, etc.. Recently, even though it is insistent that nuclear energy be so important and request in the future society, there are still strong pro and cons regarding the use of it. In this study, teaching-and-learning materials were developed dealing with using nuclear energy, and consequently they might be used in math class for the purpose of enhancement of mathematical learning ability and of recognition on nuclear energy. In this study, Material 1 included a matter of the necessity for nuclear power plants using the ratio concept, and Material 2 did on a matter of the efficiency of nuclear energy and the unclear of nuclear power plants using ratio-graph, in the elementary and upper school mathematics. Material 3 focused on a matter of the principles of nuclear power plants using the properties of exponential law in high school mathematics. Ultimately, it is hoped in the study that more diverse instructional materials dealing with diverse situations inside and outside mathematics would be developed.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.673-676
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• 2018

4차 산업혁명이 도래하면서 정보 통신 기술 및 융합 기술의 발전에 힘입어 소리 데이터를 이용한 연구가 활발하게 진행되고 있다. 소리 데이터를 이용한 학술적 프로토타입 연구들을 실제 환경에서 운용하기 위해서는 소리 취득 시 발생하는 다양한 잡음 환경에서도 원시 데이터(raw data)에 근접한 정보를 취득할 수 있는 시스템의 강인함이 보장되어야 한다. 본 논문에서는 SEGAN(Speech Enhancement Generative Adversarial Network) 모델을 활용하여, 전처리 및 후처리 과정이 필요 없이 원시 데이터를 대상으로 하는 end-to-end 방식의 소리 음질 향상 시스템을 제안한다. 제안하는 시스템은, 축산업 분야의 돼지 호흡기 질병 소리 데이터를 이용하여 실험하였으며, 여러 가지 잡음 상황(인위적인 잡음, 실제 환경 잡음)에서 소리 음질이 개선됨을 실험적으로 검증하였다.

• The Journal of the Acoustical Society of Korea
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• v.36 no.6
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• pp.419-424
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• 2017

TDoA (Time Difference-of Arrival) or DoA (Direction-of-Arrival) can be used for source localization. However, the localizing performance is dependent on relative position between source and receivers, receivers' geometric structure, sound speed, and so on. In this paper we propose a source localization method with enhanced performance that combines multiple information. The proposed method uses the time TDoA, DoA and sound speed as variables. LM (Levenberg-Marquardt) method which is one of nonlinear optimizations is applied. The performances of the proposed method was evaluated by simulation. As result of simulation, the proposed method has the lower average localizing error performance than the previous method.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.313-318
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• 2015

A traditional speech enhancement methods distort the sound spectrum generated according to estimation of the remaining noise, or invalid noise is a problem of lowering the speech recognition performance. In this paper, we propose a speech detection method that convergence the sound energy distribution process and sound energy parameters. The proposed method was used to receive properties reduce the influence of noise to maximize voice energy. In addition, the smaller value from the feature parameters of the speech signal The log energy features of the interval having a more of the log energy value relative to the region having a large energy similar to the log energy feature of the size of the voice signal containing the noise which reducing the mismatch of the training and the recognition environment recognition experiments Results confirmed that the improved recognition performance are checked compared to the conventional method. Car noise environment of Pause Hit Rate is in the 0dB and 5dB lower SNR region showed an accuracy of 97.1% and 97.3% in the high SNR region 10dB and 15dB 98.3%, showed an accuracy of 98.6%.