• Phonetics and Speech Sciences
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• v.12 no.4
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• pp.91-98
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• 2020

This study investigated the acoustic characteristics of sustained vowel /a/ and sentence utterance produced by patients with muscle tension dysphonia (MTD) using cepstrum-based acoustic variables. 36 women diagnosed with MTD and the same number of women with normal voice participated in the study and the data were recorded and measured by ADSVTM. The results demonstrated that cepstral peak prominence (CPP) and CPP_F0 among all of the variables were statistically significantly lower than those of control group. When it comes to the GRBAS scale, overall severity (G) was most prominent, and roughness (R), breathiness (B), and strain (S) indices followed in order in the voice quality of MTD patients. As these characteristics increased, a statistically significant negative correlation was observed in CPP. We tried to classify MTD and control group using CPP and CPP_F0 variables. As a result of statistic modeling with a Random Forest machine learning algorithm, much higher classification accuracy (100% in training data and 83.3% in test data) was found in the sentence reading task, with CPP being proved to be playing a more crucial role in both vowel and sentence reading tasks.

• The Journal of the Acoustical Society of Korea
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• v.28 no.8
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• pp.697-705
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• 2009

An unsupervised (blind) method is proposed aiming at extracting rhythmic sources from commercial polyphonic music whose number of channels is limited to one. Commercial music signals are not usually provided with more than two channels while they often contain multiple instruments including singing voice. Therefore, instead of using conventional modeling of mixing environments or statistical characteristics, we should introduce other source-specific characteristics for separating or extracting sources in the under determined environments. In this paper, we concentrate on extracting rhythmic sources from the mixture with the other harmonic sources. An extension of nonnegative matrix factorization (NMF), which is called nonnegative matrix partial co-factorization (NMPCF), is used to analyze multiple relationships between spectral and temporal properties in the given input matrices. Moreover, temporal repeatability of the rhythmic sound sources is implicated as a common rhythmic property among segments of an input mixture signal. The proposed method shows acceptable, but not superior separation quality to referred prior knowledge-based drum source separation systems, but it has better applicability due to its blind manner in separation, for example, when there is no prior information or the target rhythmic source is irregular.

• Journal of the Korean earth science society
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• v.40 no.1
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• pp.24-36
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• 2019

In the mid-eastern Yellow Sea, glacio-eustatic sea-level fluctuations and a regional tectonic subsidence have combined to represent an aggradational stacking pattern of sedimentary units during late Pleistocene-Holocene. The accumulated sediments are divisible into two-type units of Type-A and Type-B in high-resolution air-gun seismic profiles and the deep-drilled core of YSDP-105. Type-A unit largely comprises clast-rich coarse-grained sediments of non-marine to paralic origin, whereas Type-B unit consists mostly of tidal fine-grained sediments. Based on a bottom model of the sedimentary units, this study suggested a geoacoustic model of long-coring bottom layers at the YSDP-105 drilling site of the mid-eastern Yellow Sea. The geoacoustic model of 64-m depth below the seafloor with four-layer geoacoustic units was reconstructed in continental shelf strata at 45 m in water depth. For actual modeling, the geoacoustic property values of the models were compensated to in situ depth values below the seafloor using the Hamilton modeling method. We suggest that the geoacoustic model will be used for geoacoustic and underwater acoustic experiments of mid- and low-frequency reflecting on the deep bottom layers in the mid-eastern Yellow Sea.

• Journal of Korea Water Resources Association
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• v.54 no.3
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• pp.181-190
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• 2021

In this study, a large-scale levee breach experiment from lateral overflow was conducted to verify the effect of the new reinforcement method applied to the levee's surface. The new method could prevent levee failure and minimize damage caused by overflow in rivers. The levee was designed at the height of 2.5 m, a length of 12 m, and a slope of 1:2. A new material mixed with biopolymer powder, water, weathered granite, and loess in an appropriate ratio was sprayed on the levee body's surface at a thickness of about 5 cm, and vegetation recruitment was also monitored. At the Andong River Experiment Center, a flow (4 ㎥/s) was introduced from the upstream of the A3 channel to induce the lateral overflow. The change of lateral overflow was measured using an acoustic doppler current profiler in the upstream and downstream. Additionally, cameras and drones were used to analyze the process of the levee breach. Also, a new method using 3D point cloud for calculating the surface loss rate of the levee over time was suggested to evaluate the performance of the levee reinforcement method. It was compared to existing method based on image analysis and the result was reasonable. The proposed 3D point cloud methodology could be a solution for evaluating the performance of levee reinforcement methods.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.539-549
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• 2024

This study employed text mining techniques like frequency analysis, word clouds, and LDA topic modeling to assess consumer satisfaction and dissatisfaction with Hyundai Motor Company in the Chinese market, compared to brands such as Toyota, Volkswagen, Buick, and Geely. Focusing on compact vehicles from these brands between 2021 and 2023, this study analyzed customer reviews. The results indicated Hyundai Avante's positive factors, including a long wheelbase. However, it also highlighted dissatisfaction aspects like Manipulate, engine performance, trunk space, chassis and suspension, safety features, quantity and brand of audio speakers, music membership service, separation band, screen reflection, CarLife, and map services. Addressing these issues could significantly enhance Hyundai's competitiveness in the Chinese market. Previous studies mainly focused on literature research and surveys, which only revealed consumer perceptions limited to the variables set by the researchers. This study, through text mining and comparing various car brands, aims to gain a deeper understanding of market trends and consumer preferences, providing useful information for marketing strategies of Hyundai and other brands in the Chinese market.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.4
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• pp.343-349
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• 2011

Seabed topography and marine site survey should be performed first in the design and construction of marine structures. We could successfully acquire the seafloor topography information can be obtained by bathymetric survey and side scan sonar and the sediment layer thickness and 3D bedrock depth by seismic reflection. It is necessary to apply carry out the integrated interpretation to each other in the ocean civil Eng. In this paper, we have obtained information on the sea bottom topography and water depth at the same time using interferometer technique and on the basement depth by seismic reflection. We have performed to assess the proposed method on the seafloor topographic survey with bedrock.

• Journal of the Korean earth science society
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• v.28 no.3
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• pp.367-373
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• 2007

A geoacoustic modeling has been developed to predict sound transmission through the submarine layers of sediment and rock. It demands a geoacoustic model with the measured, extrapolated, and predicted values of geoacoustic parameters controlling acoustic propagation. In the coastal areas of Okgye and Bukpyeong, the East Sea, the marine succession consists of Quaternary/Tertiary deposits and acoustic basement. The basement of Okgye coastal area is indicative of siliciclastics of the Pyeongan Group in Paleozoic, and the average velocities of P-wave and S-wave are 4276 m/s and 2400 m/s, respectively. The basement of Bukpyeong coastal area is indicative of limestone of the Joseon Supergroup in early Paleozoic, and the average velocities of P-wave and S-wave are 5542 m/s and 2742 m/s, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.263-270
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• 1996

Noise control of a plate structure with multiple disk shaped piezoelectric actuators is studied. The plate is excited by an acoustic pressure field produced by a noise source located below the plate. Finite element modeling is used for the plate structure that supports a combination of three dimensional solid, flat shell and transition elements. The objective function, in the optimization procedure, is to minimize the sound energy radiated onto a hemispherical surface of given radius and the design parameters are the locations and sizes of the piezoelectric actuators as well as the amplitudes of the voltages applied to them. Automatic mesh generation is addressed as part of the modeling procedure. Numerical results for both resonance and off resonance frequencies show remarkable noise reduction and the optimal locations of the actuators are found to be close to the edges of the plate structure. The optimized result is robust such that when the acoustic pressure pattern is changed, reduction of radiated sound is still maintained. The robustness of an optimally designed structure is also tested by changing the frequency of the noise source using only the actuator voltages as design parameters.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.6
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• pp.669-676
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• 2010

Visualization requires for effective analysis of the spatial data collected by various sensors. The best way to convey 3D digital spatial information which is modeling of the real world to the users, realistic 3D visualization and display technology. Since most of the display is based on 2D or 2.5D projection to the plane, there is limitation in representing real world in 3D space. In this paper, data from airborne LiDAR for topographic mapping, Flashi-LiDAR as emerging sensor with great potential to 3D data acquisition, and multibeam echo-sounder for underwater measurement, were stereoscopically visualized. 3D monitors are getting popular and could be information media and platform in geoinformatics. Therefore, study on creating 3D stereoscopic contents of spatial information is essential for new technology of stereo viewing systems.

• The Transactions of the Korea Information Processing Society
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• v.3 no.1
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• pp.95-106
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• 1996

The most fundamental difference between general three dimensional computer graphics technology and virtual reality technology lies in the degree of realism as we feel, and thus the virtual reality method heavily relies on such tolls as data gloves, 3D auditory system to enhance human perception and recognition. Although these tolls are valid for such purpose, more essential ingredient. This paper provides further realism by modeling active interactions between the objects inside scenes. For this purpose, this paper proposes and implements a field model where the virtual reality space is treated as a physical field defined on the characteristic radius of stimulus and sense corresponding to the individual object. In the field model, the rule of cause and effect as an essential feature of the realism can be interpreted simply as an energy exchange between objects and consequently, variation on the radius information together with behavioral logic alone can build the virtual environment where each object can react to other objects actively and controllably.