• Phonetics and Speech Sciences
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• v.6 no.2
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• pp.47-54
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• 2014

The purpose of this study was to analyze spectral versus cepstral measurements in esophageal speakers. The comparison between the measurements in thirteen male esophageal speakers was compared with the control group of thirteen normal speakers using the sustained vowel /a/. The main results can be summarized as below: (a) the CPP and L/H ratio of the esophageal group were significantly lower than those of the control group (b) the CPP was significantly correlated with the spectral parameters such as jitter, shimmer, NHR and VTI, and (c) the ROC analysis showed that the threshold of 10.25dB for the CPP achieved a good classification for esophageal speakers, with 100% perfect sensitivity and specificity. Thus, it was known that cepstral-based acoustic measures such as CPP, may be more reliable predictors than other spectral-based acoustic measures such as jitter and shimmer. And it was found that cepstral-based acoustic measures were effective in distinguishing esophageal voice quality from normal voice quality. This research will contribute to establishing a baseline related to speech characteristics in voice rehabilitation with laryngectomees.

• Journal of Korean Society of Disaster and Security
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• v.10 no.2
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• pp.21-28
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• 2017

Wind turbulence data is required for engineering calculations of gust speeds, mean and fluctuating loading. Spectral densities are required as input data for methods used in assessing dynamic response. This study is concerned with the estimation of daily instantaneous maximum wind velocity in the meteorological major cities (selected each 6 points) during the yearly 1987-2016.12.1. The purpose of this paper is to present the power spectral densities of the daily instantaneous maximum wind velocity. In the processes of analysis, used observations data obtained at Korea Meteorological Adminstration(KMA), it is assumed as a random processes. From the analysis results, in the paper estimated power spectral densities function(Blunt model) shows a very closed with von Karman and Solari's spectrum models.

• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.247-256
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• 2016

An analysis of light curves and spectra of observed gamma-ray bursts in gamma-ray ranges is frequently demanded because the prompt emission contains immediate details regarding the central engine of gamma-ray bursts (GRBs). We have revisited the relationship between the collimation-corrected peak luminosity and the spectral lag, investigating the lag-luminosity relationships in great detail by focusing on spectral lags resulting from all possible combinations of channels. Firstly, we compiled the opening angle data and demonstrated that the distribution of opening angles of 205 long GRBs is represented by a double Gaussian function having maxima at ~ 0.1 and ~ 0.3 radians. We confirmed that the peak luminosity and the spectral lag are anti-correlated, both in the observer frame and in the source frame. We found that, in agreement with our previous conclusion, the correlation coefficient improves significantly in the source frame. It should be noted that spectral lags involving channel 2 (25-50 keV) yield high correlation coefficients, where Swift/Burst Alert Telescope (BAT) has four energy channels (channel 1: 15-25 keV, channel 2: 25-50 keV, channel 3: 50-100 keV, channel 4: 100-200 keV). We also found that peak luminosity is positively correlated with peak energy.

• Korean Journal of Remote Sensing
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• v.3 no.1
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• pp.1-10
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• 1987

The study was performed to recognize the most preferable spectral chennels for discriminating geological materials using the portable radiometer. The portable radiometer covers the visible and short infrared regions from approximately 0.4 to 2.5 microns which are coincided with Landsat TM, and the rock samples used for the study are pyrophylites, andesites, granite, granodiorite and silicified sedimentary rocks which are collected in Yangsan-Dongrae fault area. The analysis of the rock sample provides a preliminary basis for determining the wavelength regions showing diagnostic spectral features and for discriminating hydrothermal altered rocks from the unaltered rocks. The measurement of spectral of spectral reflectance for the rock samples was carried out in the laboratory which environment condition such as temperature, light sources, and humidity are constant. The analysis of the measured data was based on correlation between the reflectance value of the rock samples, and the follow discriptions are output of the study. 1) Pyrophyllite shows absorption at 0.83 $\mu\textrm{m}$ due to the oxidation of pyrite, and absorption at 2.22 $\mu\textrm{m}$ due to OH. 2) The altered rocks have generally higher reflectance than the unaltered rocks. 3) The ratio mesurement of pyrophyllites shows strong absorption at band 5/6 and band 6/4(in Landsat TM 5/7, 7/4). The ratio 1/5(Landsat TM 1/5) may be useful to discriminate andesite from the granite.

• Phonetics and Speech Sciences
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• v.11 no.3
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• pp.23-29
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• 2019

This study acoustically examines the quality of fricatives produced by ten dysarthric speakers with cerebral palsy. Previous similar studies tend to focus only on sibilants, but to obtain a better understanding of how dysarthria affects fricatives we selected a range of samples with different places of articulation and voicing. The Universal Access (UA) Speech database was used to select thirteen words beginning with one of the English fricatives (/f/, /v/, /s/, /z/, /ʃ/, /ð/). The following four measurements were taken for both dysarthric and healthy speakers: phoneme duration, mean spectral peak, variance and skewness. Results show that even speakers with mild dysarthria have significantly longer fricatives and a lower mean spectral peak than healthy speakers. Furthermore, mean spectral peak and variance showed significant group effects for both healthy and dysarthric speakers. Mean spectral peak and variance was also useful for discriminating several places of articulation for both groups. Lastly, spectral measurements displayed important group differences when taking severity into account. These findings show that in general there is a degradation in the production of fricatives for dysarthric speakers, but difference will depend on the severity of dysarthria along with the type of measurement taken.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1753-1760
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• 2005

The pseudo spectral method is applied to the free vibration analysis of double-span Timoshenko beams. The analysis is based on the Chebyshev polynomials. Each section of the double-span beam has its own basis functions, and the continuity conditions at the intermediate support as well as the boundary conditions are treated separately as the constraints of the basis functions. Natural frequencies are provided for different thickness-to-length ratios and for different span ratios, which agree with those of Euler-Bernoulli beams when the thickness-to-length ratio is small but deviate considerably as the thickness-to-length ratio grows larger.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.253-258
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• 2012

We revisit the relation between the peak luminosity $L_{iso}$ and the spectral time lag in the source frame. Since gamma-ray bursts (GRBs) are generally thought to be beamed, it is natural to expect that the collimation-corrected peak luminosity may well correlate with the spectral time lag in the source frame if the lag-luminosity relation in the GRB source frame exists. With 12 long GRBs detected by the Swift satellite, whose redshift and spectral lags in the source frame are known, we computed $L_{0,H}$ and $L_{0,W}$ using bulk Lorentz factors ${\Gamma}_{0,H}$ and ${\Gamma}_{0,W}$ archived in the published literature, where the subscripts H and W represent homogeneous and wind-like circumburst environments, respectively. We have confirmed that the isotropic peak luminosity correlates with the spectral time lag in the source frame. We have also confirmed that there is an anti-correlation between the source-frame spectral lag and the peak energy, $E_{peak}$ (1 + z) in the source frame. We have found that the collimation-corrected luminosity correlates in a similar way with the spectral lag, except that the correlations are somewhat less tight. The correlation in the wind density profile seems to agree with the isotropic peak luminosity case better than in the homogeneous case. Finally we conclude by briefly discussing its implications.

• Korean Journal of Remote Sensing
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• v.21 no.5
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• pp.405-415
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• 2005

It is difficult to classify tidal flat surface that is composed of a mixture of mud, sand, water and microphytobenthos. We used a Linear Spectral Unmixing (LSU) method for effectively classifying the tidal flat surface characteristics within a pixel. This study aims at 1) detecting algal mat using LSU in the Saemangeum tidal flats, 2) determining a suitable end-member selection method in tidal flats, and 3) find out a habitual characteristics of algal mat. Two types of end-member were built; one is a reference end-member derived from field spectrometer measurements and the other image end-member. A field spectrometer was used to measure spectral reflectance, and a spectral library was accomplished by shape difference of spectra, r.m.s. difference of spectra, continuum removal and Mann-Whitney U-test. Reference end-members were extracted from the spectral library. Image end-members were obtained by applying Principle Component Analysis (PCA) to an image. The LSU method was effective to detect microphytobenthos, and successfully classified the intertidal zone into algal mat, sediment, and water body components. The reference end-member was slightly more effective than the image end-member for the classification. Fine grained upper tidal flat is generally considered as a rich habitat for algal mat. We also identified unusual microphytobenthos that inhabited coarse grained lower tidal flats.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.3
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• pp.222-235
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• 2015

The purpose of this study is to suggest guidelines for riser fatigue analysis in terms of selection of reasonable analysis method. Three analysis methods (spectral, regular wave, rain-flow counting) are introduced and compared. As the riser systems give non-linear response, the time-domain analysis method is more preferred than frequency-domain analysis method. The spectral fatigue analysis method, however, is still useful for identifying fatigue prone areas. Once stress RAO is established, fatigue damage can be calculated very quickly. The regular wave method and the rain-flow counting method are more time consuming but give more exact results compare to spectral method. In case of regular wave method, a set of regular waves which represent random sea states is considered for dynamic analysis. The rain-flow counting method is the most intuitive and exact method because it refers time history stresses containing most of non-linear effects of the riser system. However, it is not common for early design stage to use rain-flow counting method because of its high cost. In this study, it was confirmed that the regular wave method is the most cost effective way in specific cases. However, if the system is highly non-linear, it seems that the regular wave method gives less accurate results than rain-flow counting method. Therefore, it is imperative that the engineers select appropriate analysis method based on design stage and given engineering period. This paper also discusses the theoretical background of each calculation method and hydrodynamic aspects of marine riser systems. A steel catenary riser (SCR) line on FPSO was considered and marine dynamic program (OrcaFlex) was used for static and dynamic analysis.

• Economic and Environmental Geology
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• v.36 no.3
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• pp.201-212
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• 2003

Recently, the ability of earthquake detection in the Kyungsang Basin of southeastern Korean Peninsula is greatly improved since seismic stations including seismic network of KIGAM(Korea Institute of Geoscience and Mineral Resources) have been significantly increased. However, a large number of signals from explosions are recorded because of frequent medium to large chemical explosions. The discrimination between natural earthquakes and explosions in the Basin has become an important issue. High frequency local records from 43 earthquakes and 43 explosions with comparable magnitude are selected to establish a reliable discrimination technique in the Basin. Several discrimination techniques in spectral domain using spectral amplitude ratios among Pg, Sg, and Lg waves are widely examined with tile selected data. Among them the Pg/Lg spectral ratio method is appeared to be a good discrimination technique to improve the discrimination power. Multivariate discriminant analysis is also applied to the Pg/Lg spectral ratios. The discrimination power of the Pg/Lg ratios for distance corrected three component record compared to uncorrected vertical component one shows distinct improvement. In the frequency band 4 to 14 Hz, Pg/Lg spectral ratio for distance corrected three component record provides discrimination power with a total misclassification probability of only 0.89%.