• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.165-169
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• 2002

현재 개발 중에 있는 비파괴 검사법인 Tapping Sound Analysis 의 검증을 위해 실험으로 측정된 타격음(태핑음)과 수치해석으로 구한 타격음을 비교하였다. 손상이 없는 복합재료 구조물과 손상이 있는 복합재료 구조물을 제작하고 타격 실험을 통해 타격음과 타격력을 측정하였다. 타격음의 수치 모사를 위해 동적접촉 알고리듬을 이용한 유한요소법과 경계요소법을 이용하였다. Wavelet packet transform에 근거한 특성 추출법을 이용하여 타격음으로부터 손상 판단을 위한 특성을 추출하였다. 손상이 없는 구조물과 손상이 있는 구조물의 특성을 비교하기 위해, 특성 지수를 정의하였다. 실험 결과와 수치해석 결과의 비교를 통해 타격음 계산에 사용된 수치모델의 타당성을 밝혔다.

• Composites Research
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• v.17 no.1
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• pp.1-9
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• 2004

A new non-destructive evaluation method using tapping sound is proposed. This method, named Tapping Sound Analysis, is using the difference between tapping sound data of healthy structure and defective structure as the criteria of determination of internal defect of composite structure. For the characterization of tapping sound, a feature extraction method based on wavelet packet transform is proposed. And a feature index is defined for the decision of existence of internal defects. To prove the possibility of proposed method as a non-destructive evaluation method, experimental study is performed. The tapping sound data of healthy structure and defective structure are measured and compared based on the proposed decision method. The experimental results showed that the feature index is a good indicator for the determination of internal defects.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.114-117
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• 2002

현재 개발 중에 있는 비파괴 검사법인 Tapping Sound Analysis 의 실험적 검증을 위한 연구를 수행하였다. 손상이 없는 복합재료 구조물과 손상이 있는 복합재료 구조물에 대한 타격 실험을 통해 타격음과 타격력을 측정하여 비교하였다. Wavelet packet transform에 근거한 특성 추출법을 이용하여 타격음으로부터 손상 판단을 위한 특성을 추출하였다. 손상이 없는 구조물과 손상이 있는 구조물의 특성을 비교하기 위해, 특성 지수를 정의하였다. 정의된 특성 지수를 이용하여 손상이 없는 구조물과 손상이 있는 구조물의 타격음의 차이를 하나의 실수로 표현하였다.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.381-383
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• 2016

본 연구에서는 기존의 피아노와 다른 음색을 갖는 피아노를 기획하고자 하였다. 이를 위해서 피아노 현의 1/2지점, 1/3지점, 1/17지점을 타격했을 때의 배음의 구성을 EDISON의 pianostring 프로그램을 통해 분석하였다. 440Hz의 진동수를 갖는 A4음을 기음으로 하여 각 지점을 타격했을때의 음을 합성하였다. 또한 기음과 첫 두 배음으로 구성된 화음을 합성하였다. 음색을 분석하기 위해 설문조사를 통해 7개의 항목에 대해 평가하였다. 결과적으로 망치의 타격 지점을 변화시킴으로서 원하는 음색을 얻을 수 있을 것이라 기대한다. 일례로 1/2지점을 타격할 때 단일음과 화음의 음색 차이가 확연하게 드러나 효과적인 감정표현을 할 수 있을 것으로 예상된다.

• Journal of the Korea Society of Computer and Information
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• v.28 no.1
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• pp.137-142
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• 2023

In This paper, we propose a determine the correlation between bat swing speed and balance ability in elementary school baseball players. This study subjects were 40 subjects. Bat swing speed was measured using a zepp2baseball, and balance ability was measured using a biorescue. For the measurement of balance ability, eyes open surface·eyes open length·eyes open average speed·eyes close surface·eyes close length·eyes close average speed were measured. pearson's correlation analysis was used to analyze the correlation between bat swing speed and balance ability. There was a significant negative correlation between bat swing speed and eyes close surface (r=-0.366, p<0.05). There was a significant negative correlation between bat swing speed and eyes close length(r=-0.348, p<0.05). There was a significant negative correlation between bat swing speed and eyes close average speed(r=-0.455, p<0.01). Among them, eyes close average speed showed the highest correlation (p<0.01). These findings suggest that improvement of the balance ability has a positive effect on bat swing speed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.595-598
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• 2005

The impact sound of the golf club is one of the major factors to purchase it. Sound qualify evaluation techniques are mostly developed for harmonic sounds. Sound quality metrics for the impact sound is proposed in this study. Jury test, one of the typical subjective evaluation scheme, is carried out for evaluating the sound quality of 11 different golf drivers. Above subjective classification results are assumed to be the right answers. Conventional objective evaluation methods such as Zwicker loudness sensory pleasantness are calculated. Wavelet analysis and instantaneous loudness are applied in order to evaluate the transient sounds, which shows better correlation with the results from those by jury test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.5 s.110
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• pp.537-543
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• 2006

The impact sound of the golf club is one of the major factors to purchase it. Sound quality metrics has been mostly developed for harmonic sounds. Sound quality evaluation techniques for the impact sound have been contrived in this study. Jury test, one of the typical subjective evaluation scheme, is carried out for evaluating the sound quality of 13 different golf drivers, which classification results are assumed to be correct answers. Conventional objective evaluation methods such as Zwicker loudness sensory pleasantness are calculated. Wavelet analysis and instantaneous loudness are applied in order to evaluate the sound quality of transient sounds, which scheme shows better correlation with the results from jury test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.526-527
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• 2014

• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.328-334
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• 2015

This paper describes an acoustic analysis of a Jing, Korean percussion instrument, according to different drive point and blow strength, and this analysis is focused on the softening and beat phenomena. Three kinds of blow strength (very strong, strong, and weak) and three locations of drive point (center, up, and right) are applied, and the spectrogram function built in Matlab is utilized to analyzing the softening and beat of target sounds. The stronger blow you drive to the center of the Jing, the more clearly softening is observed. Frequency shifting is increased proportionally to the blow strength and frequency and it is stand out on the harmonics in contrast with that of other partials. Beat of the Jing can be classified into the early beat and late beat. The beats by the outside driven Jing are distributed in wider frequency band than the beats by the center driven Jing. In addition, it is observed that the early beat is affected by few specific partials developed around harmonics for the center driven Jing.

• Journal of Korea Multimedia Society
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• v.14 no.11
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• pp.1500-1506
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• 2011

This paper is to propose for the production of a digital-based new interface for the percussion of samulnori which are drum, janggu, jing and kkwaenggwari. Newly designed interface is similar to a jing-shaped percussion, and it was designed to playall of four instruments from a single interface. Two batting sufaces, which are located both in front and at trunk of the interface, generate a hitting date creating when interface to be hit and a pressure data when to grip the handle by control unit located at the handle. The information generated is transmitted to a computer via a wireless communication, and then, the computer generate a synthesized sound based on the characteristic of each instrument.