• Structural Engineering and Mechanics
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• v.41 no.5
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• pp.663-673
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• 2012

A number of mode shape-based structure damage identification methods have been verified by numerical simulations or experiments for on-line structure health monitoring (SHM). However, many of them need a baseline mode shape generated by the healthy structure serving as a reference to identify damages. Otherwise these methods can hardly perform well when multiple cracks conditions occur. So it is important to solve the problems above. By aid of the fractal dimension method (FD), Qiao and Wang proposed a generalized fractal dimension (GFD) to detect the delamination damage. As a modification of GFD, Qiao and Cao proposed the approximate waveform capacity dimension (AWCD) technique to simplify the calculation of fractal and overcome the false peak appearing in the high mode shapes. Based on their valued work, this paper combined and applied the AWCD method and curvature mode shape data to detect multiple damages in beam. In the end, the identification properties of the AWCD for multiple damages have been verified by groups of Monte Carlo simulations and experiments.

• The Journal of the Acoustical Society of Korea
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• v.27 no.1E
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• pp.11-16
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• 2008

In this paper, a pitch cycle waveform (PCW) is extracted, quantized, and interpolated in a time domain to synthesize high-quality speech at low bit rates. The pre-alignment technique is proposed for the accurate and efficient PCW extraction, which predicts the current PCW position from the previous PCW position assuming that pitch periods evolve slowly. Since the pitch periods are different frame by frame, the original PCW is converted into the fixed-dimension PCW using the dimension-conversion method, and subsequently quantized by code-excited linear predictive (CELP) coding. The excitation signal for the linear predictive coding (LPC) synthesis filter is generated using the time-domain interpolation and interlink of the quantized PCW's. The coder operates at 4.2 kbit/s and 3.2 kbit/s depending on the pitch period. Informal listening test demonstrates the effectiveness of the proposed coding scheme.

• Speech Sciences
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• v.3
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• pp.148-155
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• 1998

As an application of dimensional analysis in the theory of chaos and fractals, we studied and estimated the information dimension for various phonemes. By constructing phase-space vectors from the time-series speech signals, we calculated the natural measure and the Shannon's information from the trajectories. The information dimension was finally obtained as the slope of the plot of the information versus space division order. The information dimension showed that it is so sensitive to the waveform and time delay. By averaging over frames for various phonemes, we found the information dimension ranges from 1.2 to 1.4.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.167-174
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• 1998

The ultrasonic test is recognized for its significance as a non-destructive testing method to detect volume defects such as porosity and incomplete penetration which reduce strength in the weld zone. This paper illustrates the defect detection in the weld zone of ferritic carbon steel using ultrasonic wave and the evaluation of pattern recognition by chaotic feature extraction using time series signal of detected defects as data. Shown in the time series data were that the time delay was 4 and the embedding dimension was 6 which indicate the geometric dimension of the subject system and the extent of information correlation. Based on fractal dimension and lyapunov exponent in quantitative chaotic feature extraction, feature value of 2.15, 0.47 is presented for porosity and 2.24, 0.51 for incomplete penetration The precision rate of the pattern recognition is enhanced with these values on the total waveform of defect signal in the weld zone. Therefore, we think that the ultrasonic pattern recognition method of weld zone defects of ferritic carbon steel by ultrasonic-chaotic feature extraction proposed in this paper can boost precision rate further than the existing method applying only partial waveform.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.1
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• pp.186-191
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• 2009

In the study on the waveform analysis of radial artery pulse diagnosis, we need to establish fundaments of contemporary pulse diagnosis research. As we will to do experimental research on the difference of pulse waveform on the radial artery with applied variations of pressure(5 stage-pressure) and measuring position(CHON, KWAN, CHEOG). First of all, in this research, we did the experiment of the study on the waveform analysis of radial artery(left KWAN) pulse dignosis by using 3 dimension pulse meter and analyzer (3D MAC). As a result. we extracted the seven measurement fluents : energy(E), size of cycle(h1), size of reflection cycle(h2), time of reflection cycle(t2), time of contraction (t4), width of cycle(w), area of waveform(A) by the statistically reasonable differences. We expect that the seven measurement fluents contribute to divide the situation through the results of waveform analysis of radial artery.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1963-1969
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• 2017

In order to overcome the manufacturing difficulty of the transverse-flux permanent magnet linear motor (TFPMLM) and enhance its performance much better, a novel TFPMLM with E-core and 3 dimension (3D) magnetic structures is proposed in this paper. Firstly, its basic structure and operating principle are presented. Then the equivalent 2D configuration of the TFPMLM is transformed, so that the Schwarz-Christoffel (SC) mapping method can be used to analyze the motor. Furthermore, the air gap flux density distribution is solved by SC mapping method, based on which, the EMF waveform, no-load cogging force waveform and load force waveform are obtained. Finally, the prototyped TLPMLM is manufactured and the results are obtained from the experiment and 3D FEM, respectively, which are used to compare with those from SC mapping method.

• Progress in Medical Physics
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• v.23 no.1
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• pp.1-7
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• 2012

The purpose of this study was to develop the respiratory training system using individual characteristic guiding waveform to reduce the impact of respiratory motion that causes artifact in radiotherapy. In order to evaluate the improvement of respiratory regularity, 5 volunteers were included and their respiratory signals were acquired using the in-house developed belt-type sensor. Respiratory training system needs 10 free breathing cycles of each volunteer to make individual characteristic guiding waveform based on Fourier series and it guides patient's next breathing. For each volunteer, free breathing and guided breathing which uses individual characteristic guiding waveform were performed to acquire the respiratory cycles for 3 min. The root mean square error (RMSE) was computed to analyze improvement of respiratory regularity in period and displacement. It was found that respiratory regularity was improved by using respiratory training system. RMSE of guided breathing decreased up to 40% in displacement and 76% in period compared with free breathing. In conclusion, since the guiding waveform was easy to follow for the volunteers, the respiratory regularity was significantly improved by using in-house developed respiratory training system. So it would be helpful to improve accuracy and efficiency during 4D-RT, 4D-CT.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.19-24
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• 2000

Effects of the cross-sectional dimension and moisture profile of wood specimens on the ultrasonic sound velocities of radiata pine heartwood and sapwood. Each moisture profile model specimen was made by composing five wood pieces with various moisture contents. As the cross-sectional dimensions decreased the ultrasonic velocities of both heartwood and sapwood decreased by 4~8%. In the ultrasonic signals transmitted through the specimens low frequency components more dominated than high frequency components as the dimension of cross section increased. The specimens with the same average MCs and different moisture profiles showed different ultrasonic velocities. By plotting the ultrasonic velocities against the average moisture contents of the inner three pieces of the moisture profile model specimens it was revealed that three distinct plot patterns existed.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1784-1786
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• 2004

PD(Partial Discharge) signal emitted from PD sources has their intrinsic features in the region of time and frequency. STFT(Short Time Fourier Transform) shows time-frequency distribution at the same time. 2-Dimensional matrices(33${\times}$77) from STFT for PD pulse signals are a good feature vectors and can be decreased in dimension by wavelet 2D data compression technique. Decreased feature vectors(13${\times}$24) were used as inputs of Back-propagation ANN(Artificial Neural Network) for discrimination of Multi-PD sources(air discharge sources(3), surface discharge(1)). They are a good feature vectors for discriminating Multi-PD sources.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.7
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• pp.332-338
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• 2005

PD(Partial Discharge) signal emitted from PD sources has their intrinsic features in the region of time and frequency STFT(Short Time Fourier Transform) shows time-frequency distribution at the same time. 2-Dimensional matrices(33$\times$77) from STFT for PD pulse signals are a good feature vectors and can be decreased in dimension by wavelet 2D data compression technique. Decreased feature vectors(13$\times$24) were used as inputs of Back-propagation ANN(Artificial Neural Network) for discrimination of Multi-PD sources(air discharge sources(3), surface discharge(1)). They are a good feature vectors for discriminating Multi-PD sources in the air.