• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.58-68
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• 2000

This paper proposes a sinusoidal modeling of polyphonic audio signals. Sinusoidal modeling which has been applied well to speech and monophonic signals cannot be applied directly to polyphonic signals because a window size for sinusoidal analysis cannot be determined over the entire signal. In addition, for high quality synthesized signal transient parts like attacks should be preserved which determines timbre of musical instrument. In this paper, a multiresolution filter bank is designed which splits the input signal into six octave-spaced subbands without aliasing and sinusoidal modeling is applied to each subband signal. To alleviate smearing of transients in sinusoidal modeling a dynamic segmentation method is applied to subbands which determines the analysis-synthesis frame size adaptively to fit time-frequency characteristics of the subband signal. The improved dynamic segmentation is proposed which shows better performance about transients and reduced computation. For various polyphonic audio signals the result of simulation shows the suggested sinusoidal modeling can model polyphonic audio signals without loss of perceptual quality.

• Journal of Power Electronics
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• v.9 no.5
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• pp.757-771
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• 2009

This paper proposes a systematic approach to the modeling of the small-signal characteristics of three-phase bridge boost rectifiers under non-sinusoidal conditions. The main obstacle to the conventional synchronous d-q frame modeling approach is that it is unable to identify a steady-state under non-sinusoidal conditions. However, for most applications under non-sinusoidal conditions, the current loops of boost rectifiers are designed to have a bandwidth that is much higher than typical harmonics frequencies in order to achieve good current control for these harmonic components. Therefore a quasi-static method is applied to the proposed modeling approach. The converter small-signal characteristics developed from conventional synchronous frame modeling under different operating points are investigated and a worst case point is then located for the current loop design. Both qualitative and quantitative analyses are presented. It is observed that operating points influence the converter low frequency characteristics but hardly affect the dominant poles. The relationship between power stage parameters, system poles and zeroes is also presented which offers good support for the system design. Both the simulation and experimental results verified the analysis and proposed modeling approach. Finally, the practical case of a parallel active power filter is studied to present the modeling approach and the resultant regulator design procedure. The system performance further verifies the whole analysis.

• Smart Structures and Systems
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• v.21 no.3
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• pp.335-347
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• 2018

The fast-growing number of mobile and wearable applications has driven several innovations in small-scale electret-based energy harvesting due to the compatibility with standard microfabrication processes and the ability to generate electrical energy from ambient vibrations. However, the current modeling methods used to design these small scale transducers or microgenerators are applicable only for constant-speed rotations and small sinusoidal translations, while in practice, large amplitude sinusoidal vibrations can happen. Therefore, in this paper, we formulate an analytical model for electret-based microgenerators under general sinusoidal excitations. The proposed model is validated using finite element modeling combined with numerical simulation approaches presented in the literature. The new model demonstrates a good agreement in estimating both the output voltage and power of the microgenerator. This new model provides useful insights into the microgenerator operating mechanism and design trade-offs, and therefore, can be utilized in the design and performance optimization of these small structures.

• The Journal of the Acoustical Society of Korea
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• v.22 no.2
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• pp.96-103
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• 2003

This paper describes a method for sinusoidal modeling of audio signals using perceptually weighted matching pursuit. Matching pursuits extracts iteratively the greatest energy signals from the input signals until the residual between the original and the reconstructed signal is zero. In this paper, perceptual matching pursuits using psychoacoustic model to matching pursuit extracts greatest perceived energy iteratively. To evaluate the performance of the perceptual matching pursuits it is compared with the sinusoidal matching pursuits which is not included perceptual weighting. For various audio signals the result of simulation shows that the perceptual matching pursuit is superior to the sinusoidal matching pursuits, especially for a high change rate in time domain it can synthesized original signal.

• The Journal of the Acoustical Society of Korea
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• v.22 no.4E
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• pp.141-149
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• 2003

As music of digital form has been widely used, many people have been interested in the automatic extraction of natural information of music itself, such as key of a music, chord progression, melody progression, tempo, etc. Although some studies have been tried, consistent and reliable results of musical information extraction had not been achieved. In this paper, we propose a method to extract chord and tempo information from general polyphonic music signals. Chord can be expressed by combination of some musical notes and those notes also consist of some frequency components individually. Thus, it is necessary to analyze the frequency components included in musical signal for the extraction of chord information. In this study, we utilize a sinusoidal modeling, which uses sinusoids corresponding to frequencies of musical tones, and show reliable chord extraction results of sinusoidal modeling. We could also find that the tempo of music, which is the one of remarkable feature of music signal, interactively supports the chord extraction idea, if used together. The proposed scheme of musical feature extraction is able to be used in many application fields, such as digital music services using queries of musical features, the operation of music database, and music players mounting chord displaying function, etc.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2
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• pp.77-85
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• 2001

This paper proposes a method of time-scale modification of polyphonic audio signals based on a sinusoidal model. The signals are modeled with sinusoidal component and noise component. A multiresolution filter bank is designed which splits the input signal into six octave-spaced subbands without aliasing and sinusoidal modeling is applied to each subband signal. To alleviate smearing of transients in time-scale modification a dynamic segmentation method is applied to subbands which determines the analysis-synthesis frame size adaptively to fit time-frequency characteristics of the subband signal. For extracting sinusoidal components and calculating their parameters matching pursuit algorithm is applied to each analysis frame of subband signal. In accordance with spectrum analysis a psychoacoustic model implementing the effect of frequency masking is incorporated with matching pursuit to provide a resonable stop condition of iteration and reduce the number of sinusoids. The noise component obtained by subtracting the synthesized signal with sinusoidal components from the original signal is modeled by line-segment model of short time spectrum envelope. For various polyphonic audio signals the result of simulation shows suggested sinusoidal modeling can synthesize original signal without loss of perceptual quality and do more robust and high quality time-scale modification for large scale factor because of representing transients without any perceptual loss.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.149-155
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• 2007

The counter emf(electromotive forces) of a permanent magnet multi-phase brushless motor is generally a non-sinusoidal wave or a non-ideal trapezoid. So, conventional modeling using a sinusoidal wave or an ideal trapezoid counter emf can result in errors. In order to reduce modeling errors for simulation and analysis the properties of a multi-phase brushless AC motor, this paper proposes a phase variable model that is a mixed modeling technique using both Finite Element Analysis(FEA) based circuits and motor voltage equations. The phase model parameters including the counter emf voltage waveform are obtained by using of FEA, and the mixed modeling technique based on circuits and equations is used to implement a simulation model for multi-phase brushless AC motors with any counter emf voltage waveforms. Adequacy of the proposed model is established from the simulation and experimental results for a seven-phase brushless motor.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.380-386
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• 2000

This paper presents the mathematical modelling analysis of Brushless Synchronous Motor(BLSM). The dynamic and the steady state characteristics of BLSM are simulated and analyzed : electromagnetic torque, speed, line voltage, and current. We used mathematical modelling to model of BLSM with sinusoidal back EMF, namely the shaft transformation referencing rotor frame from a, b, c three to produce constant torque like synchronous motor. The experiment result has already similar to compare with simulation result : torque error about 7%, speed error about 5%. The validity of proposed modelling and analysis was confirmed by the experimental result.

• Structural Engineering and Mechanics
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• v.81 no.6
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• pp.751-767
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• 2022

In the hogging bending moment area, continuous composite beams are subjected to the ultimate limit state of lateral-torsional buckling (LTB), which depends on web stiffness as well as concrete slab and shear connection stiffnesses. The design of the LTB and the determination of the elastic critical moment are produced approximately, using the European Standard EN 1994-1-1:2004, for continuous composite steel beams, but is applicable only for those with a plane web steel profile. Also, and from the previous researches, the elastic critical moment of the continuous composite beams with corrugated sinusoidal web steel profiles was determined. In this paper, a finite element analysis (FEA) model was developed using the ANSYS 16 software, to determine the elastic critical moments of continuous composite steel beams with various corrugated web profiles, such as trapezoidal, zigzag, and rectangular profiles, which were evaluated against numerical data of the sinusoidal one from the literature. Ultimately, the failure load of a composite steel beam with various web profiles was predicted by studying 46 models, based on FEA modeling, and a procedure for predicting the elastic critical moment of composite beams with various web steel profiles was proposed. When compared to sinusoidal web profiles, the trapezoidal, zigzag, and rectangular web profiles required an average increase in load capacity and stiffness of 7%, 17.5%, and 28%, respectively, according to the finite element analysis. Also, the rectangular web steel profile has a greater stiffness and load capacity. In contrast, the sinusoidal web has lower values for these characteristics.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.1
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• pp.105-113
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• 2007

In this paper, we propose the matching pursuit with damping factors, a new sinusoidal model improving the matching pursuit, for the codecs based on sinusoidal model. The proposed model defines damping factors by using a correlativity of parameters between the current and adjacent frame, and estimates sinusoidal parameters more accurately in analysis frame by using the matching pursuit according to damping factor, and synthesizes the final signal. Then it is possible to model efficiently without interpolation schemes. The proposed sinusoidal model shows a better speech quality without an additional delay than the conventional sinusoidal model with interpolation methods. Through the SNR(signal to noise ratio), the MOS(Mean Opinion Score), LR(Itakura-Saito likelihood ratio), and CD(cepstral distance), we compare the performance of our model with that of matching pursuit using interpolation methods.