• 대한전기학회논문지:시스템및제어부문D
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• 제54권12호
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• pp.737-740
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• 2005

This paper describes the possibility of evaluating and classifying arthritic pathology using the acoustical analysis of knee joint sound. Six normal subjects and 11 patients with knee problems were enrolled. Patients were divided into the 1st patient group which required an orthopeadic surgery and the 2nd patient group of osteoarthritis. During sitting and standing periods, subjects' active knee flexion and extension were monitored. Fundamental frequency, mean amplitude of pitch, jitter and shimmer were analyzed according to the position. The results demonstrate that the values of fundamental frequency, jitter and shimmer of the 2nd patient group were larger than others and changed unstably. The values of the standing position were larger than the sitting position.

• 말소리와 음성과학
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• 제9권1호
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• pp.41-47
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• 2017

The main advantage of the statistical parametric speech synthesis is its flexibility in changing voice characteristics. A personalized text-to-speech(TTS) system can be implemented by combining a speech synthesis system and a voice transformation system, and it is widely used in many application areas. It is known that the fundamental frequency and the spectral envelope of speech signal can be independently modified to convert the voice characteristics. Also it is important to maintain naturalness of the transformed speech. In this paper, a speech synthesis system based on Hidden Markov Model(HMM-based speech synthesis, HTS) using the STRAIGHT vocoder is constructed and voice transformation is conducted by modifying the fundamental frequency and spectral envelope. The fundamental frequency is transformed in a scaling method, and the spectral envelope is transformed through frequency warping method to control the speaker's vocal tract length. In particular, this study proposes a voice transformation method using the correlation between fundamental frequency and vocal tract length. Subjective evaluations were conducted to assess preference and mean opinion scores(MOS) for naturalness of synthetic speech. Experimental results showed that the proposed voice transformation method achieved higher preference than baseline systems while maintaining the naturalness of the speech quality.

• Structural Engineering and Mechanics
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• 제69권2호
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• pp.155-162
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• 2019

It is very common to find an empirical formulation in an earthquake design code to calculate fundamental vibration period of a structural system. Fundamental vibration period or frequency is a key parameter to provide adequate information pertinent to dynamic characteristics and performance assessment of a structure. This parameter enables to assess seismic demand of a structure. It is possible to find an empirical formulation related to reinforced concrete structures, masonry towers and slender masonry structures. Calculated natural vibration frequencies suggested by empirical formulation in the literatures has not suits in a high accuracy to the case of rest of the historical masonry bridges due to different construction techniques and wide variety of material properties. For the listed reasons, estimation of fundamental frequency gets harder. This paper aims to present an empirical formulation through Mean Square Error study to find ambient vibration frequency of historical masonry bridges by using a non-linear regression model. For this purpose, a series of data collected from literature especially focused on the finite element models of historical masonry bridges modelled in a full scale to get first global natural frequency, unit weight and elasticity modulus of used dominant material based on homogenization approach, length, height and width of the masonry bridge and main span length were considered to predict natural vibration frequency. An empirical formulation is proposed with 81% accuracy. Also, this study draw attention that this accuracy decreases to 35%, if the modulus of elasticity and unit weight are ignored.

• 대한기관식도과학회:학술대회논문집
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• 대한기관식도과학회 1993년도 제27차 학술대회 초록집
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• pp.69-69
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• 1993

음성 기본주파수는 성대 전체의 단순한 진동에 의해 형성되며 음성의 특징을 결정하는 가장 중요한 요소 중의 하나이다. 저자들은 후두질환의 발견과 치료의 기초로 이용하고자 20대 성인 남녀 각각 50명과 10세 내외의 소아 남녀 각각 40명을 대상으로 외후두의 크기와 기본주파수를 측정하여 다음과 같은 결과를 얻었다. 1. 성인에서 평균 외후두의 크기는 남자 37.8$\pm$3.15 mm, 여자 31.0$\pm$3.19 mm였고 기본주파수의 평균은 남자가 117.8$\pm$10.09 Hz, 여자가 220.26$\pm$13.75 Hz로 각각 통계학적으로 유의하게 차이가 있었다. (p<0.05) 3. 소아에서 평균 외후두의 크기는 남자 25.67$\pm$4.53 mm, 여자 27.28$\pm$2.77 mm였고 기본주파수의 평균은 남자가 224.88$\pm$15.89 Hz, 여자가 239.25$\pm$15.92 Hz로 통계학적으로 유의하게 차이가 있었다. (p<0.01) 5. 성인에서 외후두의 크기와 기본주파수는 서로 유의한 상관관계를 보였다. (r=0.48)

• 한국음향학회지
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• 제33권2호
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• pp.146-151
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• 2014

본 논문은 기존의 가야금 안족 모델을 분석하고 안족의 위치에 따른 주파수 모델링을 개선하기 위한 방법에 대해서 기술한다. 기존의 모델은 안족의 위치별 기본 주파수의 변화를 지수 함수로 가정, 리키 적분기를 이용하여 이들 주파수를 적분한 후 선형 회귀 모델을 이용하여 주파수와 안족의 위치에 관한 수식의 파라미터를 구하였다. 이 모델은 평균적으로 2.5 Hz의 오차를 보였으나 낮은 주파수에 대해서는 최대 7.75 Hz의 오차를 보였다. 이에 제안하는 모델은 안족의 위치를 세부 구간으로 나누고 각 구간 내 누적 주파수에 대한 선형 회귀 모델을 적용하였고, 리키 적분기의 계수를 바꿔가며 안족 위치의 세부 구간 내 각 현의 기본 주파수와 계산된 주파수간 RMSE(Root Mean Square Error)가 최소가 되는 계수를 찾음으로써 최적의 파라미터를 구하였다. 이러한 과정을 통해 얻어진 모델은 기존의 오차를 최대 3배가량 줄일 수 있었다.

• 말소리와 음성과학
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• 제8권4호
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• pp.15-22
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• 2016

This study aims to examine whether the fundamental frequency (F0) varies depending on languages or distinguishes between L1 (first language) and L2 (second language) speech and whether the type of materials which vary in control of consonant voicing affects the use of F0-especially, mean F0. For this purpose, we compared productions of two languages produced by Korean L2 learners of English to those of Korean-English bilingual speakers. Twelve Korean L2 speakers of English and twelve Korean-English bilingual speakers participated in this study. The subjects read aloud 22 declarative sentences-balanced and unbalanced-once in English and once in Korean. Mean F0 of Korean was higher than that of English for both speaker groups, and the difference in the value of mean F0 between the Korean and English sentences was different depending on the type of materials that the participants read. With regard to F0 range, the L2 speakers had a larger F0 range in English than in Korean; however, the effect of language on F0 range was not statistically significant for the bilingual speakers. These results indicate that language-specific properties may affect the use of F0, in particular, mean F0.

• IEIE Transactions on Smart Processing and Computing
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• 제4권2호
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• pp.89-96
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• 2015

In this paper, time-frequency analysis algorithms, empirical mode decomposition and local mean decomposition, are reviewed and their applications to nonlinear and nonstationary real-world data are discussed. In addition, their generic extensions to complex domain are addressed for the analysis of multichannel data. Simulations of these algorithms on synthetic data illustrate the fundamental structure of the algorithms and how they are designed for the analysis of nonlinear and nonstationary data. Applications of the complex version of the algorithms to the synthetic data also demonstrate the benefit of the algorithms for the accurate frequency decomposition of multichannel data.

• Structural Engineering and Mechanics
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• 제3권5호
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• pp.497-509
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• 1995

Effectiveness of multiple tuned mass dampers (MTMD) in suppressing the dynamic response of base excited structure for first mode vibration is investigated. The effectiveness of the MTMD is expressed by the ratio of the root mean square (RMS) displacement of the structure with MTMD to corresponding displacement without MTMD. The frequency content of base excitation is modelled as a broad-band stationary random process. The MTMD's with uniformly distributed natural frequencies are considered for this purpose. A parametric study is conducted to investigate the fundamental characteristics of the MTMD's and the effect of important parameters on the effectiveness of the MTMD's. The parameters include: the fundamental characteristics of the MTMD system such as damping, mass ratio, total number of MTMD, tuning frequency ratio, frequency spacing of the dampers and frequency content of the base excitation. It has been shown that MTMD can be more effective and more robust than a single TMD with equal mass and damping ratio.

• 말소리와 음성과학
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• 제10권2호
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• pp.69-76
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• 2018

The elderly are at increased risk of developing dysphagia due to aging and illnesses. The aim of the current study was to analyze, via an acoustic study, the change in the voice quality of normal elderly people after a 3oz water-swallow test. Subjects included a group of 60 normal elderly people (age: $mean{\pm}SD=76.9{\pm}6.66$) and 60 healthy young adults (age: $mean{\pm}SD=25.1{\pm}2.36$). Every participant produced a five-second /a/ phonation pre- and post-swallowing, and the fractioned two-second sections were analyzed using the MDVP (multi dimensional voice program) analysis. The elderly group demonstrated a post-swallowing increase in the following related acoustic parameters: fundamental frequency, fundamental frequency variation, amplitude-variation, and noise in both two-second sections. However, the younger group showed an increase only in frequency related acoustic parameters (i.e., STD ) in the first two-second section. The significant changes in values in the post-swallowing parameters might indicate temporary irregularities in pitch and amplitude along with higher amounts of noise in the voice. The results could be attributed to water residues in the vocal fold and vocal tract, as well as a deterioration of the motor and sensory functions caused by anatomical and physiological changes that result from aging.

• Steel and Composite Structures
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• 제37권4호
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• pp.391-404
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• 2020

Human-induced vibration could present a serious serviceability problem for large-span and/or lightweight floors using the high-strength material. This paper presents the results of heel-drop, jumping, and walking tests on a large-span composite steel rebar truss-reinforced concrete (CSBTRC) floor. The effects of human activities on the floor vibration behavior were investigated considering the parameters of peak acceleration, root-mean-square acceleration, maximum transient vibration value (MTVV), fundamental frequency, and damping ratio. The measured field test data were validated with the finite element and theoretical analysis results. A comprehensive comparison between the test results and current design codes was carried out. Based on the classical plate theory, a rational and simplified formula for determining the fundamental frequency for the CSBTRC floor is derived. Secondly, appropriate coefficients (β_rp) correlating the MTVV with peak acceleration are suggested for heel-drop, jumping, and walking excitations. Lastly, the linear oscillator model (LOM) is adopted to establish the governing equations for the human-structure interaction (HSI). The dynamic characteristics of the LOM (sprung mass, equivalent stiffness, and equivalent damping ratio) are determined by comparing the theoretical and experimental acceleration responses. The HSI effect will increase the acceleration response.