• Phonetics and Speech Sciences
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• v.10 no.4
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• pp.147-154
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• 2018

Wet voice quality (WVQ) is a characteristic that appears after swallowing. Although the concept is accepted by many clinicians worldwide, it is nevertheless ambiguous. In this study, we investigated WVQ in patients with swallowing disorders using acoustic analysis. A total of 106 patients diagnosed with penetration-aspiration by the videofluoroscopic swallowing study (VFSS) were recruited. A voice recording of vowel /a/ was conducted before and after the VFSS, and an acoustic analysis was then performed using PRAAT. Voice after VFSS was used for a perceptual judgment and divided into two groups: the Wet group (48 patients) and the Non-wet group (58 patients). At the post-VFSS stage, the two groups displayed significant differences in many acoustic parameters including F0_SD, Jitter, RAP, Shimmer, APQ, HNR, NHR, FUF, DVB, and CPP. The parameter affecting judging wetness resulted into Jitter and NHR by the logistic regression test. At the pre-VFSS stage, the two groups differed significantly in many acoustic parameters including Intensity, Jitter, RAP, Shimmer, NHR, FUF, DVB, and CPP. Both pre-and post-VFSS, the mean values of all significant parameters, except Intensity, HNR, and CPP, were higher in the Wet group. According to pre-and post-VFSS, the two groups displayed interactions in many parameters (Intensity, F0_SD, Jitter, RAP, Shimmer, APQ, HNR, NHR, FUF, DVB, and CPP). In particular, Intensity increased in both groups after the VFSS, although the increase in the Non-wet group was greater. Based on these results, it was conjectured that the WVQ after swallowing resulted from the secretion effect of the mucous membrane due to the dry laryngeal characteristic of elderly patients, rather than aspiration resulting in food on the vocal cords.

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.60 no.9
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• pp.454-462
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• 2017

Background and Objectives The present study aimed to investigate the effects of penetration/aspiration (P/A) on voice acoustic parameters. Subjects and Method Twenty-seven patients were analyzed with the videofluoroscopic swallowing study (VFSS) and then divided into two groups based on the modified Penetration and Aspiration Scale results. Ten patients (5 males and 5 females) were included in the Non-P/A group, and 17 patients (12 males and 5 females) in the P/A group. Stroke was the major cause of swallowing disorders. Three sustained /a/ vowels recorded in pre- and post-VFSS were analyzed. Mann-Whitney U-test was used to compare acoustic values before and after VFSS, and the receiver operating characteristics (ROC) curve with combination of significant parameters was also conducted. Results Among acoustic parameters, the length of analyzed sample (p=0.010), number of segments computed (p=0.018), total number detected pitch periods (p=0.017), and second formant (p=0.013) in pre- and post-VFSS were significantly different between Non-P/A and P/A groups. In the P/A group after VFSS, the means of these significant parameters decreased. According to ROC combined with four significant parameters, the probability of predicting P/A condition was 84% (p=0.005), the sensitivity was 80%, and the specificity was 80%. Conclusion Voice acoustic analysis can reflect voice changes by penetration/aspiration and the combination of significant parameters can also detect swallowing disorders. Therefore, voice analysis can be a reliable screening tool for patients with swallowing disorders.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.545-555
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• 2020

This paper presented efficient transceiver structure using sub-band processing for underwater communication in terms of covertness and performance improvement. In aspect of covertness, encrypted coded-bits are divided into groups, and center frequency and sub band are determined by coded-bits of each group. Therefore, as center frequencies are changed randomly, it maintain the covertness effectively. In aspect of performance improvement, the performance of underwater communication mainly depends on multi-path propagation characteristics, Doppler-spread, and frame synchronization. Accordingly, in order to overcome these effects, non-coherent energy detector and turbo equalization method are employed in receiver side. Furthermore, optimal frame synchronization was proposed. Through the simulation and lake experiment, performance analysis was conducted. Especially in the lake experiment, as a result of applying optimal frame synchronization method to receiver structure, errors are corrected in most frames.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1097-1107
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• 2020

A methodology has been proposed to understand the spatiotemporal changes of the river topography through the longitudinal change of the geometric characteristics of the cross-sections and the properties related thereto. Three-dimensional spatial information of the riverbed was obtained through the detailed bathymetry survey using an acoustic echo sounder for the reach from Gumi Weir to Chilgok Weir in the Nakdong river. Geometric informations for the reference sections were extracted using the acquired bathymetry survey data. By comparing the geometric properties for the reference sections, it was possible to catch the topographic characteristics and its changes over a reach of the channel. Through comparison with past survey data, it was also possible to quantitatively grasp the amount of change in cross-sectional area and volumetric change of riverbed. It is expected that a quantitative evaluation of river topography changes will be possible by applying the method proposed in this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.161-170
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• 2022

The maintenance of bridges installed in rivers is carried out through facility safety inspection and repair & reinforcement procedures according to the results. Many studies have been so far conducted on the safety check of the bridge upperstructure because of the ease of access. However as it is impossible to directly investigate whether the pier foundation installed in the river has been scoured. Management of underwater foundations has remained based on theory. In this study, the scour of the bridge foundation installed in such a river was realized in 3D form by using an echo sounder and VRS. This made it possible to predict the scour pattern through comparison and analysis with the ground height of the riverbed at the time of the bridge installation. Based on these results, if the pier foundation is used as an initial data to determine whether or not local scour is present and to predict long-term scouring, bridge collapse due to foundation scour can be prevented.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.5
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• pp.35-43
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• 2022

Precise modeling and analysis of closed bomb test(CBT) combustion using solid propellants was performed. The fluid structure interaction(FSI) method was implemented to analyze the gas and solid phases at the same time. The Eulerian analysis method was applied for the gas phase and grain combustion, and the Lagrangian analysis method was implemented for the grain movement. The interaction between the solid phase grains and the combustion gas was fully coupled through the source term. The volume of fluid(VOF) method was used to simulate the burning distance of the grain and the movement of the combustion surface. The force acting on the grain was comprised of the pressure and gravity acting on the grain burning surface, and the grain burning rate and grain movement speed were considered in the velocity term of the VOF. The combustion analysis was performed for both one and three grains, and fairly compared with the experiments. The acoustic field during grain combustion due to pressure fluctuations was also analyzed.

• Journal of Korea Entertainment Industry Association
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• v.13 no.8
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• pp.209-221
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• 2019

A found-footage film La France est notre patrie is a documentary, in which archive images are juxtaposed with intertitles, non-diegetic music and foley, by borrowing an audiovisual strategy of silent films. The filmmaker Rithy Panh has excavated the images, which had been taken during the same period as the film history of the end of the 19^th and early 20^th centuries in Southeast Asia and Africa under French colonial rule. This paper examines the filmmaker's methods of historiography when utilizing archive images in order to represent the past by referring to Walter Benjamin's concept of historical montage and dialectical image. As the analysis illustrates the singularity of constructive methods, which include multi-layer viewpoints and montage styles of compilation and collage, it reveals how La France est notre patrie elicits the essay film modes through its self-reflexivity, leads audience to the threshold of critical thinking about time and history and creates a discourse of counter-memory.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.230-230
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• 2021

하상변동은 하천을 효과적으로 활용하고, 하천 내 시설물을 유지관리하기 위한 중요한 정보 중 하나이다. 특히, 최근 4대강 사업으로 인한 하상변동 측정에 대한 수요가 높아짐에 따라 하상변동 측정에 대한 수요가 높아지고 있다. 하상변동 측정하기 위한 방법은 일반적으로 경험식 및 모델링과 실측에 의한 방법으로 구분할 수 있다. 경험식 및 모델링에 의한 방법은 대상 하천과 환경 조건에 따라 결과가 상이하게 나타나며, 실측에 의한 방법은 계측기기를 활용한 지점 단위의 측정에 의존하고 있다. 쉽게 말해 기존의 하상변동 측정은 높은 불확실성 보이며, 많은 인력과 비용, 그리고 시간이 소요되는 한계가 있다. 따라서 본 연구에서는 기존 하상변동 측정의 한계를 극복하고, 하상의 움직임과 특성을 파악할 수 있는 AMV(Acoustic Mapping Velocimetry)를 도입하였다. AMV는 초음파를 이용하여 수심을 측정하는 음향 측심기에서 얻은 측정 결과를 바탕으로 초음파 영상을 생성하고, 영상 분석을 통해 하상의 움직임과 특성을 파악하는 알고리즘이다. 본 연구는 AMV의 일환으로, MBES로 측정된 자료를 기반으로 하상의 움직임을 조사하기 위해 AMV를 적용한 실증적 연구로 시도되었다. 본 연구에서 제시한 기술은, 1) ADCP, MBES를 통해 측정된 수심 정보를 초음파 하상 영상을 변환, 2) 연속 초음파 영상에 LSPIV와 같은 영상 유속계 기술을 도입하여 하상 이동속도를 산정, 3) 연속 초음파 영상에서 하상의 평균하상고, 파장 등의 특성을 파악, 4) Exner 방정식을 활용한 하상변동량 산정으로 구성된다. 본 연구에서 제시된 기술은 사용자의 경험과 판단에 의한 영향을 최소화하여 비교적 낮은 불확실성을 가지며, 비교적 적은 인력과 비용, 시간이 소요되는 경제성을 갖추고 있다. 뿐만 아니라 공간적으로 측정된 초음파 영상을 활용한 많큼 상대적으로 넓은 범위에 적용할 수 있다. 따라서 향후 국내 하상변동 연구에 기여를 할 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.233-233
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• 2021

ADCP(Acoustic Doppler Current Profiler)는 유수의 흐름을 방해하지 않으면서 수중에 발사된 음파의 도플러 효과를 이용하여 3차원 유속 측정이 가능한 초음파 유량측정장비이다. 2009년부터 다양한 하천에서 ADCP 사용량이 증가하면서 ADCP를 이용한 유량측정 기법과 현장 적용상의 문제, 자료처리 과정에서의 문제점들이 발생하고 있다. 이런 문제점들을 분석한 결과 다음과 같은 사례들이 나타났다. 첫 번째 하상이 매우 불규칙한 단면의 부적절한 측정 사례, 두 번째 하안 수직벽 존재에 따른 단면의 부적절한 측정 사례, 세 번째 수심 오측이 다수 발생한 측정 사례, 네 번째 유속 프로파일 결측이 다수 발생한 측정 사례, 다섯 번째 통신문제로 인한 주기적인 결측이 발생한 측정 사례, 여섯 번째 홍수기 고농도 유사로 인해 결측이 발생한 사례, 일곱 번째 수중식생의 영향으로 수심 및 유속 프로파일 오측이 발생한 측정 사례, 여덟 번째 이동상 조건이 발생한 측정 사례 등 많은 문제들이 발생하였다. 본 연구에서는 수중식생의 영향으로 수심 및 유속 프로파일 오측이 발생하는 사례에 대해 개선할 수 있는 방안을 연구하였다. ADCP에서 수중에 발사한 음파 중 식생에 부딪친 강한 반사파의 노이즈로 side-lobe현상에 의한 오측 및 결측이 발생한다. 현재 오측 및 결측 자료는 ADCP 제조사별 자료 취득 소프트웨어의 기능에 의존 하거나, USGS의 OSW(Office of Surface Water) Hydroacoustics의 QRev를 이용하여 후처리 과정을 거쳐 측정 자료로 정리하고 있다. 이에 본 연구에서는 노이즈로 인한 side-lobe 현상을 물리적인 방법으로 제거하기 위해 음향 녹음 과정에서 노이즈를 물리적인 방법으로 제거하는 윈드실드와 팝 필터를 고려한 ADCP필터를 개발하여 적용하였다. 이번 연구의 대상지점은 원주시(지정대교)수위관측소로 5월 이후 수중에 식생이 성장하는 지점이다. 먼저 ADCP필터를 제거한 상태에서 측정을 실시하고, 이후 ADCP필터를 장착하여 측정을 실시하였다. ADCP필터 적용의 측정성과에서는 노이즈에 의한 오측 및 결측이 다수 발생하는 것을 볼 수 있고, ADCP필터를 적용한 측정성과에서는 노이즈가 제거되어 오측 및 결측이 개선되는 결과를 볼 수 있었다. 본 연구에서는 수중식생 영향으로 강한 반사파에 의한 노이즈로 side-lobe현상에 의한 ADCP측 정성과의 오측 및 결측을 ADCP필터를 적용하여 물리적인 방법으로 노이즈를 제거 할 수 있다는 결과를 얻었다.

• Phonetics and Speech Sciences
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• v.15 no.2
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• pp.43-51
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• 2023

In this paper, we propose an approach for dialect classification based on the speed and pause of speech utterances as well as the age and gender of the speakers. Dialect classification is one of the important techniques for speech analysis. For example, an accurate dialect classification model can potentially improve the performance of speaker or speech recognition. According to previous studies, research based on deep learning using Mel-Frequency Cepstral Coefficients (MFCC) features has been the dominant approach. We focus on the acoustic differences between regions and conduct dialect classification based on the extracted features derived from the differences. In this paper, we propose an approach of extracting underexplored additional features, namely the speed and the pauses of speech utterances along with the metadata including the age and the gender of the speakers. Experimental results show that our proposed approach results in higher accuracy, especially with the speech rate feature, compared to the method only using the MFCC features. The accuracy improved from 91.02% to 97.02% compared to the previous method that only used MFCC features, by incorporating all the proposed features in this paper.