• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.498-501
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• 2006

When an object or objects, rigid or flexible, presents in incident sound field, the sound wave is scattered. This, we call, is scattered sound field. It, of course, depends on the amplitude and the direction of the incident sound field as well as the geometry and the surface impedance of the scatterer(object). This paper addresses the way to measure scattered sound field by using arbitrary incident sound wave. This means that the method can decompose the scattered field from measured sound field with respect to any magnitudes and directions of incident plane-waves.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제21권7호
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• pp.443-451
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• 2015

본 논문에서는 신호 모델링 기법을 이용하여 소총화기에서 발생하는 탄환충격파(SW, Shock Wave) 음향신호와 총성(MB, Muzzle Blast) 음향신호를 효과적으로 검출할 수 있는 알고리즘을 제안하였다. 전장에서 저격수의 위치를 탐지하기 위해서는 저격수의 소총화기에서 발생하는 탄환충격파와 총성 신호를 정확하게 검출하여 적 저격수의 방향각과 거리를 추정하는 것이 중요하다. 제안 알고리즘의 성능을 검증하기 위하여 국내 군 사격장에서 실제 소총화기 발사 실험을 진행하였고, 실험결과 제안 알고리즘은 탄환충격파 신호 검출에 있어 기존 알고리즘에 비해 최대 20% 가까운 성능향상을, 총성 신호 검출에 있어서는 약 5% 정도의 성능향상을 가져옴을 확인할 수 있었다.

• 전기학회논문지P
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• 제62권2호
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• pp.103-109
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• 2013

In this study, the three sounds effects on subjects due to EEG type, and it researched to find optimal sound to increase their amenity and productivity. EEG and HRV were compared and analyzed in the environmental test room by classifying subjects into two type: A and B. The condition of the environmental test room was in temperature $31[^{\circ}C]$, relative humidity 50[RH%], air current speed 0.02[m/s] and illuminance 1000[lux] with setting up three different sounds which are U type sound, V type sound and Z type sound. The result of this study, at U type sound for A and B type, relative $M{\alpha}$ wave, relative $M{\beta}$ wave and SEF50 were revitalized. Also at Z type sound for A and B type, stress index, fatigue degree and HRT were decreased and SDNN was revitalized. Therefore U type sound is very effective to increase amenity, productivity and concentration, and Z type sound is very effective to decrease stress and fatigue degree.

• 한국초등과학교육학회지:초등과학교육
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• 제35권4호
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• pp.389-405
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• 2016

The purpose of this study was to analyze elementary school teachers' understanding, certainty, and familiarity with 13 key concepts of wave physics that are presented in textbook and teacher's guidebook. 123 elementary school teachers answered concept tests and questionnaires. In the results to these tests and questionnaires, teachers demonstrated a high level of understanding and high certainty in understanding with regard to the concepts of sound generation, effect of medium on wave, timbre, wavelength, and trough and crest of wave. For the topics of sound velocity, wave reflection and wave transmission, teachers demonstrated a high level of understanding but low certainty in understanding. With regard to sound propagation, teachers demonstrated a low level of understanding and an improperly high certainty in that low understanding. Teachers lacked knowledge, i.e., displayed a low level of understanding and low certainty in sound strength, sound frequency, constructive interference and destructive interference. In constructive and destructive interference, the teachers also displayed a low level of familiarity. We analyzed the differences in teacher's understanding, certainty, and familiarity according to teacher demographics defined by the teacher's gender, teaching experience with concepts of sound, career, curriculum track while in high school, and major in university. There were no significant differences in understanding, certainty, or familiarity as defined by gender, teaching experience, and career. However, these displays of knowledge were affected by the teacher's curriculum track in high school and their major. These results suggest that the teacher's understanding of, familiarity with, and certainty in wave physics concepts are more influenced by their learning experience than by their teaching experience. Therefore, we suggest additional learning opportunities for teachers (such as teacher training programs) in order to improve teacher knowledge and correct teacher misconceptions in wave physics.

• KIEAE Journal
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• 제11권3호
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• pp.49-56
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• 2011

The effect of soundscape has been analyzed by questionnaire results. Nowadays, EEG is used to identify the human reponses due to exterior stimuli such as soundscape sound sources. So, it is very meaningful to know the EEG response to soundscape sound sources. In the present study, the sound sources of soundscape were heard to subjects in order to find out the relationship between questionnaire results and electroencephalogram results through lab test. And stimulated part of brain for evaluating words were sought in this experiment too. The results of the study are as follows : the sound source of bird+music causes more ${\alpha}$-wave rise than other sound sources and the ${\alpha}$-wave stimulated region of brain is occipitallobe. In case of ${\beta}$-wave, the left part of brain is excited. ${\delta}$-wave is on frontallobe and ${\Theta}$-wave is on right part of brain. The evaluating words for soundscape can be categorized into four groups. These results could be used for basic materials of soundscape effects analysis.

• 한국소음진동공학회논문집
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• 제17권9호
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• pp.888-894
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• 2007

The speech sound is detected by the vibration measurement of the window glass. In this study, we investigate the effect of the disturbing waves by background noise and window shaker excitation on the speech intelligibility of the detected sound. Based upon Modulation Transfer Function(MTF), speech intelligibility of the sound is objectively estimated by Speech Transmission Index(STI) As the level of the disturbing wave varies, variation of the speech intelligibility is examined. Experimental result reveals how STI is influenced by the level and frequency characteristics of the disturbing wave. By using a customized window shaker for disturbing sound, we evaluate the efficiency and the frequency characteristics of the anti-eavesdropping system. The purpose of the study is to provide useful information to prevent the eavesdropping through the window glass.

• 한국음향학회지
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• 제16권2호
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• pp.16-25
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• 1997

이 연구에서는, 반사 음파 전달 특성에 의한 공간감 효과를 이용하여 음상 정위를 개선할 수 있는 HRTF 모델링 방법을 제안하였다. 실험 결과, 최적으로 평가된 반사 음파 전달 특성을 갖는 HRTF 모델은, 직접 음파 전달 특성만으로 구성된 HRTF 모델과 비교하여 음상 전위가 약 23% 이상 개선되었다. 그리고, 적절한 공간감이 음상 정위의 정확도를 증가시킬 수 있는 요소임을 알았다.

• International Journal of Advanced Culture Technology
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• 제10권4호
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• pp.286-293
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• 2022

In this study, we extracted sound waves that can improve psychological skills for volleyball players, investigated the changes that the application training of the extracted sound waves has on the brain waves of volleyball players, and the changes in brain waves are the psychological of volleyball players. The purpose of the research is to investigate the effect on technology. In order to achieve this purpose of the study, a total of 10 people from the experimental group and 10 from the control group were selected as the research subjects of university volleyball players with more than 5 years of volleyball experience. The experimental procedure was for the experimental group to listen to sound waves for more than 30 minutes at least 4 times a week for 12 weeks, and brain waves were measured 3 times before, during, and after. In addition, psychological skills were measured twice before and after. The measured data were subjected to t-test and two-way variance repeated measures analysis using SPSS 20.0. The results obtained through this process are as follows. First, as a result of analyzing the differences in psychological skills according to sound wave application training, there were statistically significant differences in goal setting and attention factors of the experimental group. Second, as a result of repeated measurement variance analysis at each time point according to the application of the sound wave application training program, it was found that alpha waves had a synergistic effect at the statistical significance level in the experimental group. Third, as a result of repeated measurement variance analysis at each time point according to the application of the sound wave application training program, it was found that the beta wave had a synergistic effect at the statistical significance level in the experimental group.

• 한국소음진동공학회논문집
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• 제19권10호
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• pp.1053-1061
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• 2009

The goal of this paper is to investigate the generation characteristics of the main impulsive noise sources generated by the supersonic flow discharging from a muzzle. For this, this paper investigates two fundamental mechanisms to sound generation in shocked flows: shock motion and shock deformation. Shock motion is modeled numerically by examining the interaction of a sound wave with a shock. The numerical approach is validated by comparison with results obtained by linear theory for a small disturbance case. Shock deformations are modeled numerically by examining the interaction of a vortex ring with a blast wave. A numerical approach of a dispersion-relation-preserving(DRP) scheme is used to investigate the sound generation and propagation by their interactions in near-field.

• 대한기계학회논문집B
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• 제24권7호
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• pp.924-929
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• 2000

This paper addresses a new technique of measuring the mean flow velocity over the cross sectional area of the pipe using sound field reconstruction. When fluid flows in the pipe and two plane waves propagate oppositely through the medium, the flow velocity causes the change of wave number of the plane waves. The wave number of the positive going plane wave decreases and that of negative going one increases in comparison to static medium in the pipe. Theoretical backgrounds of this method are introduced in detail and the measurement of mean flow velocity using the sound field reconstruction is not affected by velocity profile upstream of microphones.