• Journal of Korean Public Health Nursing
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• v.27 no.2
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• pp.304-312
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• 2013

Purpose: This study was conducted to compare health knowledge, health attitude and health behavior of middle school students based on the hours of health educational parameters imparted. Methods: After obtaining informed consent from participants, data were collected from 474 middle school students attending three different schools. The questionnaires were developed based on previous studies and four authorized health textbooks. Data were analyzed using $x^2$-test, t-test, ANOVA and ANCOVA. Results: The scores of 34-hour or 17-hour regular health education group were higher than those of 0-hour regular health education group in the areas of health knowledge and health attitude. In contrast the score of health behavior showed no significant difference among the three groups. Conclusion: The course of regular health education should be included as an essential one rather than as a selective option in the curriculum, and 34-hour regular health education is needed for all primary, middle, and high school students who are about to developing lifelong health habits, in order to have them gradually acquire sound education of health knowledge, health attitude, and health behavior.

• Phonetics and Speech Sciences
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• v.5 no.3
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• pp.55-60
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• 2013

The purpose of this study was to investigate the acoustic characteristics of crying infants according to the communication intents such as hunger and pain in terms of acoustic differences in the fundamental frequency ($F_0$), jitter, shimmer, noise-to-harmonic ratio(NHR), habitual pitch, and intensity. The subjects were 20 healthy, normal infants, less than seven days old, from the city of Seoul and were born after 38 to 42 weeks(full term) of pregnancy. The sound of crying was recorded for three minutes. The crying due to pain was induced by means of the inborn metabolism error test, whereas the crying due to hunger was verified by means of the rooting reflex by waiting for the designated eating time. The results were as follows: (1) the fundamental frequency, noise-to-harmonic ratio(NHR), and intensity of the infants' crying due to pain was higher than that by hunger, showing a significant difference between the mean values. (2) the infants' crying due to hunger and that by pain did not have a significant difference in the mean jitter and shimmer values but both of them were largely outside of the normal threshold values(jitter by 1.04% and shimmer by 3.81%). This study was significant in the sense that it showed the acoustic characteristics of infants' crying from hunger and pain were very different from each other according to the communication intents in terms of the six acoustic parameters.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.275-282
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• 1998

The squeeze casting of a Mg-5wt%Al-0.6wt%Zr alloy was carried out to investigate the conditions for the formation and the prevention of macrodefects, such as macrosegregation and shrinkage defects. The effects of the process parameters, the applied pressure, the die temperature, and the pouring temperature on the formation of macrodefcts were investigated in correlation with the evolution of macrostructure. Three types of macrodefects were found; macrosegregation only, shrinkage defects only, both macrosegregation and shrinkage defects. It was found that the pouring temperature, the die temperature, and the applied pressure are closely related to the formation of macrodefects. Sound castings without macrosegregation and shrinkage defects can be obtained under the conditions of 80 MPa$730^{\circ}C$$760^{\circ}C$, and $180^{\circ}C$<$T_D$<$250^{\circ}C$.

• Computers and Concrete
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• v.25 no.3
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• pp.245-253
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• 2020

Vibrational analysis in microtubules is examined based on the nonlocal theory of elasticity. The complete analytical formulas for wave velocity are obtained and the results reveal that the small scale effects can reduce the frequency, especially for large longitudinal wave-vector and large circumferential wave number. It is seen that the small scale effects are more significant for smaller wave length. The methods and results may also support the design and application of nano devices such as micro sound generator etc. The effects of small scale parameters can increase vibrational frequencies of the protein microtubules and cannot be overlooked in the analysis of vibrating phenomena. The results for different modes with nonlocal effect are checked.

• The Journal of the Acoustical Society of Korea
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• v.19 no.2E
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• pp.8-13
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• 2000

In this paper, we present an adaptive formant tracking algorithm for speech using closed phase WRLS-VFF-VT method. The pitch synchronous closed phase methods is known to give more accurate estimates of the vocal tract parameters than the pitch asynchronous method. However the use of a pitch-synchronous closed phase analysis method has been limited due to difficulties associated with the task of accurately isolating the closed phase region in successive periods of speech. Therefore we have implemented the pitch synchronous closed phase WRLS-VFF-VT algorithm for speech analysis, especially for formant tracking. The proposed algorithm with the variable threshold(VT) can provide a superior performance in the boundary of phone and voiced/unvoiced sound. The proposed method is experimentally compared with the other method such as two channel CPC method by using synthetic waveform and real speech data. From the experimental results, we found that the block data processing techniques, such as the two-channel CPC, gave reasonable estimates of the formant/antiformant. However, the data windows used by these methods included the effects of the periodic excitation pulses, which affected the accuracy of the estimated formants. On the other hand the proposed WRLS-VFF-VT method, which eliminated the influence of the pulse excitation by using an input estimation as part of the algorithm, gave very accurate formant/bandwidth estimates and good spectral matching.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.772-777
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• 2006

An acoustic finite element model of a bridge is developed to evaluate the noise generated by the traffic-induced vibration of the bridge. The dynamic response of a multi-girder bridge, modeled by a 3-dimensional frame element model, is analyzed with a 3-axle(8DOF) truck model and a 5-axle(l3DOF) semi-trailer. The flat plate element is used to analyze the acoustic pressure due to the fluid-structure interactions between the vibrating surface and contiguous acoustic fluid medium. The radiation fields of noise with a specified distribution of vibrating velocity and pressure on the structural surface are also computed using the Kirchhoff-Helmholtz integral. In an attempt to illustrate the influence of the structural vibration noise of a bridge to total noise level around the bridge, the random function is used to generate the vehicle noise source including the engine noise and the rolling noise interacting between the road and tire. Among the diverse parameters affecting the dynamic response of bridge, the vehicle velocity, the vehicle weight, the spatial distribution of the road surface roughness, the stiffness degradation of the bridge and the variation of the air temperature changing the air density are found to be the main factors that increase the level of vibration noise. Consequently, The amplification rate of noise increases with the traveling speed and the vehicle weight.

• The Journal of Internal Korean Medicine
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• v.29 no.3
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• pp.666-674
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• 2008

Objectives : The aim of this study was to evaluate gastrointestinal parasympathetic nerve activation and pyloric valve function in patients with functional dyspepsia through analysis of bowel sounds and to investigate clinical characteristics associated with the parameters of bowel sounds. Method : We surveyed clinical characteristics of patients by using a questionnaire about functional dyspepsia. Bowel sounds were recorded for 15 minutes during fasting state and for 40 minutes during postprandial state. We then classified the patients into 3 groups by abnormal states of bowel sounds, specifically by the percentage of B.S. and dominenet frequency, and studied clinical characteristics in each group. Results : Among the 182 subjects, patients who had low activity of parasympathetic nerve were 25.8% and showed a tendency of female-dominant, family history and more frequent abdominal pain. Those who had pyloric valve disturbance were 24.1% and showed no tendency by sex distribution, family history and complained of indigestion sensation. Patients who had both disorders were 10.9%, and their clinical characteristics were non-specific. Conclusion : Analysis of bowel sounds may be useful in evaluating pathophysiological factors of functional dyspepsia.

• Journal of Welding and Joining
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• v.32 no.5
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• pp.50-57
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• 2014

Friction Stir Welding (FSW) is a complex process with several mutually interdependent parameters. A slight difference from known settings may lead to imperfections in the stirred zone. These inhomogeneities affect on the mechanical properties of the FSWed joints. In order to prevent the failure of the welded joint it is necessary to detect the most critical defects non-destructive. Especially critical defects are wormhole and lack of penetration (LOP), because of the difficulty of detection. Online thermography is used process-accompanying for defect detecting. A thermographic camera with a fixed position relating to the welding tool measures the heating-up and the cool down of the welding process. Lap joints with sound weld seam surfaces are manufactured and monitored. Different methods of evaluation of heat distribution and intensity profiles are introduced. It can be demonstrated, that it is possible to detect wormhole and lack of penetration as well as surface defects by analyzing the welding and the cooling process of friction stir welding by passive online thermography measurement. Effects of these defects on mechanical properties are shown by tensile testing.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.21-24
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• 2008

The present study numerically investigates the glottal airflow characteristics as well as acoustic features of phonation fully coupled with dynamic behavior of vocal folds. The vocal folds are described by a low-dimensional body-covered model characterized by bio-mechanical parameters such as glottal width, vocal folds stiffness, and subglottal pressure. The flow in the vocal tract is modeled as an incompressible, axisymmetric form of the Navier-Stokes equations (INS), while the acoustic field is predicted by the linearized perturbed compressible equations (LPCE). The computed result shows that a two-mass model of vocal folds is sufficient to reproduce temporal variations in oral airflow and glottis motion produced by female speakers. It is also found that i) the glottal width has a significant effect on the amplitude of glottal flow, and thus on the amplitude of acoustic wave in the vocal tract, ii) the vocal fold tension is the main control parameter for the fundamental frequency of phonation, iii) the subglottal pressure plays an appreciable role on reproduction of the self-sustained oscillation of vocal folds, and iv) the strength of pulsating airflow and vortical structures are primarily affected by glottal width and subglottal pressure, and are closely related to pitch, loudness, and voice quality. Finally, more comprehensive explanation about the difference between one- and two-mass models is presented with discussion of effectiveness of vocal folds oscillation and voice quality.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.349-355
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• 2018

A large number of parameters have been defined in order to describe and to evaluate the acoustical propeTies in rooms. Reverberation time is an impoTant characteristic of conceT halls, theaters and studios, etc. Over the years, a number of different methods for measuring the reverberation time have been developed, the most common being: the interrupted noise method, the integrated impulse response method, and the method of recording the room response to an impulsive source. However, the reverberation time can be changed by the measurement method, sound source and microphone. Therefore, it is difficult to accurately measure the reverberation time in a room. In this paper, it will be analyzed the interpretation method of the reverberation time and discussed the limitations.