• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.207-212
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• 2019

A flat-type piezoelectric ceramic ultrasonic transmitter was successfully fabricated for application in acoustic devices with cone-free diaphragms. The transmitter, possessing a center frequency of 40.6 kHz, exhibited a higher displacement characteristic for a multilayer type compared with a single layer type. Surface roughness treatment of an Al elastic diaphragm influenced a slight increase (1.1 dB) in the sound pressure level (SPL) at $10V_{rms}$ due to the enlarged surface area. The fabricated multilayer piezoelectric ceramic ultrasonic transmitter showed increasing SPL with increasing input voltage, with a maximum SPL of approximately 123.6 dB at $10V_{rms}$. This implies a doubly increased SPL density of $3.6dB/mm^3$, superior to that of a commercial open-type transmitter with a cone.

• Science of Emotion and Sensibility
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• v.25 no.1
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• pp.55-66
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• 2022

Many studies have shown that musical dissonance generally evokes negative affect, but few studies detail how distinct dissonant intervals, ranging in various roughness, influence emotions and cognition. This research entailed two experiments to confirm whether varying musical intervals of dissonance trigger particular negative emotions and increase cognitive interference. Experiment 1 assumed that different dissonant intervals would elicit distinct negative emotions. In a survey involving 131 participants, there was an overwhelming consensus that dissonant intervals elicited stronger high arousal negative affect than low arousal negative affect. The major 7th degree was found to evoke a significantly stronger feeling of scared. Experiment 2 investigated whether emotions-affecting dissonance would have an enhancing effect on cognitive interference. According to a color-word Stroop task conducted on 81 participants, the presence of any dissonant sound caused significantly higher reaction times and error rates than in the absence of sound. In particular, the minor 2nd degree was cognitively the most disruptive and associated with the slowest reaction times. This paper shows how different ranges of dissonance can effectively influence negative affect and heighten cognitive interference.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.23-30
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• 2003

It is very important to detect and evaluate the surface or subsurface flaws because of their influences on mechanical properties of materials. Rayleigh wave and creeping wave are commonly used for the detection of surface and subsurface flaws. These techniques, however, have following problems. Each amplitudes are remarkably affected by the surface condition and evaluation of echo pattern is usually difficult because shear wave mode propagate in the material at the same time. On the other hand, surface SH-wave which is horizontally polarized shear wave traveling along near surface layer is an attractive technique for the surface or subsurface material characterization and this technique is useful to solve the problems mentioned above. In this paper, The stability and transmission coefficient of SH waves through a viscous fluid layer is theoretically studied and simulated. Its results agreed well with the theoretical expectation for the experimental verification. These experimental results show that viscosity of couplants, thickness of couplant and surface roughness are closely related to transfer efficiency in surface SH angle beam method.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.173-178
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• 1988

The purpose of the study was to confirm the influence of fluoride to enamel decalcification. Specimens were prepared from 20 extracted teeth. Every tooth was sliced into 4 pieces by means of seperating disc. The pieces with sound enamel were distributed to 4 groups. 1st group was treated with 0.5% NaF solution for 2 minutes. 2nd group was treated with 0.5% NaF solution for 10 minutes. 3rd group was treated with 1% NaF solution for 2 minutes. 4th group was treated with 1% NaP solution for 10 minutes. The enamel surface of each specimen were decalcified with 30% $H_3PO_4$ for 2 minutes and the findings through electron microscope were as follows; 1. The degree of decalcification on the 1st group was greater than that of the 2nd group. 2. Roughness of the 3rd group was slightly higher than that of the 4th group. 3. Under the same procedure of decalcification, the specimen treated by higher conceutration of NaF solution for same length of time showed less decalcified picture. 4. Under the same procedure, of decalcification, the specimens treated by same concentration of NaF solution for different length of time, were compared and found longer the time less decalcified.

• 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.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.405-409
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• 2008

This technical paper is proposing a sound concept in the application of the rehabilitation method of the water supply steel pipe in the large diameter ranged from 1,800mm to 3,500mm. There were conducted the experimental tests for the specimens as well as the real steel pipe of diameter 2,200mm. The water pressure ejected from nozzle tip should be at least 2,500bar to have the satisfied surface profiles required in the design criterion. The most difficult thing is to keep the water pressure at the nozzle tip as 2,500bar during the consecutive work in the interval of the work site more than 1km. It is found that the method suggested in this study is adequate method to meet the specified design criteria. The results of this study provide the useful information how to setup the equipments for the successful work. This method also provides not only the omission of the blasting process but also the effect of the budget reduction.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.9 no.1
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• pp.47-52
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• 1998

Objectives : To compare the objective differences in voice quality and voice problems between clergies and normal male control group. Materials and Methods : The sustained vowel sound of 46 clergies and 40 normal persons were analyzed, using a videostroboscopy and acoustic analyzer. Together with these analyses, a questionnaire associated with current and past voice problems was handed over to the patients. Results : The most common symptom in subjective group was the voice fatigue. Stroboscopic findings in subjective group were as following 23 cases(50%) of pachydermia, 17 cases(37%) of phase difference, 12 cases(25%) of anterior-posterior contracture, 6 cases(13%) of vocal polyp and 3 cases(7%) of vocal nodule. The mean maximal phonation time in clergies was 17.8 seconds and in control group was 19 seconds. litter, pitch perturbation quotient and shimmer were significantly increased in subjective group than in control group(p<0.05), but there were no significant differences between two groups in fundamental frequency, vFo, amplitude perturbation quotient and noise to harmonic ratio. Conclusion : In the clergies using loud and forceful voice, vocal polyp and functional voice disorder findings were frequently noted in stroboscopic examination. litter and shimmer, reflecting the roughness of voice, were increased in acoustic analysis. Therefore, clergies, classified into untrained professional voice users, need professional career guidance and counseling.

• The Journal of the Acoustical Society of Korea
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• v.29 no.1E
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• pp.38-44
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• 2010

This paper is based on our comments and proposed amendments to the documents, Annex A, Phantom for determining Maximum Depth of Penetration, and Annex B, Local Dynamic Range Using Acoustical Test Objects 87/400/CDV. IEC 61391-2 Ed. 1.0 200X, prepared by IEC technical Committee 87; Ultrasonics. The documents are concerned with the influence of microstructure of reference target material on the ultrasonic backscattering. Previous works on the attenuation due to backreflection and backscattering of reference target materials are reviewed. The drawback to the use of ungraded stainless steel and metallic materials without microstructural data such as, crystal structure, basic acoustic data of sound velocity and attenuation, grain size, roughness and elastic constants has been discussed. The analysis suggested that the insightful conclusion can be made by differentiating the influence arising from target size and microstructure on the backscattering measurements. The microstructural parameters are associated with physical, geometrical, acoustical and mechanical origins of variation with frequency. Further clarification of such a diverse source mechanisms for ultrasonic backscattering would make the target material and its application for medical diagnosis and therapy simpler and more reliable.

• Tribology and Lubricants
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• v.32 no.6
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• pp.207-211
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• 2016

To interpret the perception that originates from tactile sensibility during people touch and recognize the object surfaces, this study focuses on the development of a friction model that can describe the interaction of a stylus pen sliding over the counter surfaces. In addition, the study includes several other experimental factors such as the pressure, temperature, and topology of surface, which can have an effect on the emotional user experience concerning various surfaces; this research aims to suggest a method to quantitatively evaluate the relation between these experimental parameters and emotional user experience. Accordingly, the objective of research comprises the friction characteristic technology for measurement of fine tribological behavior and a standard to quantify the emotional feedback. Existing panels or input devices that provide interaction feedback about user actions simply operate with a single frequency vibration or sound response. On the contrary, this research investigates various interaction characteristics including friction force, frequency, and surface topology synthetically. Using the developed model, which can explain the relation between the friction parameters and emotional user experience, developers can design their product in order to provide the user with expected emotional sensibility. Consequently, it can contribute to reduce the development cost about sensitivity model.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.2
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• pp.103-109
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• 2016

Efficacy of cosmetics has been mainly evaluated by qualitative and quantitative methods based on visual sense, tactile sense and skin structure until now. In this study, we suggested a novel evaluation method for skin status based on sound; measuring and analyzing the rubbing noise generated by applying cosmetics. First, the rubbing noise was measured at a close range by a high-sensitivity microphone in anechoic environment, and the noises were analyzed by 1/3 octave band analysis in frequency-domain. Three conditions, 1) before washing, 2) after washing and 3) after application of cosmetics, were compared. As a result, sound pressure level (SPL) of rubbing noise after washing was larger than that of before washing, and the SPL of rubbing noise after cosmetic application was the smallest. Furthermore, the energy of rubbing noise after application was higher than that of the before and after washing conditions in a low frequency band (lower than 2 kHz region). Conversely, the energy of rubbing noise after application was much lower than the others in a high-frequency band (upper than 2 kHz region). This change of energy distribution was described as a balloon-skin model. High SPL in the low frequency region after the cosmetic applications was due to the increase of "flexibility index", while SPL in the high frequency region significantly decreased because of the attenuation which is related to "softness index". Therefore, we developed two indices based on the spectrum-energy difference for evaluating skin conditions. This proposed method and indices were verified via skin flexibility and roughness measurement using cutometer and primos respectively. These results suggest that acoustic measurement of skin friction noise may be a new skin status evaluation method.