• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.323-326
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• 1998

The paper describes a theoretical and experimental study on the speed of the torsional elastic waves propagating in an axisymmetirc waveguide whose cross-sectional area varies periodically as an harmonic function of the axial coordinate. The approximate solution of the phase speed has been obtained using the perturbation technique for sinusoidal modulation of small amplitude. The experiment verifying the theoretical result consists of transmitting and receiving torsional waves by magnetostriction and measuring the wave speed in the waveguides with threaded surfaces.

• Bulletin of the Korean Mathematical Society
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• v.35 no.2
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• pp.269-278
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• 1998

Let ($G,\;{\upsilon}$) be a bounded smooth domain and reflection vector field on $\partial$G, which points uniformly into G. Under the condition that locally for some coordinate system, ${\mid}{\upsilon^i}{\mid}\;i\;=\;1,{\cdot},{\cdot}$,d - 1, where is constant depending on the Lipschitz constant of G, we have tightness for reflected diffusion with jump on G with reflection $\upsilon$ depending only on c. From this, we obtain some properties of L-harmonic function where L is a sum of Laplacian and integro one.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1064-1066
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• 2001

In this paper, the harmonic components generated by those two sources are analyzed separately based on the transfer function and shown as the closed form considering the switching frequency, speed of the control processor, gain of the controller, and the inductor and capacitor value of L-C filter. A design procedure is described with one flow chart and explained step by step.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.174-178
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• 2005

This paper presents a novel fuzzy logic based control method for shunt active filters. Since the fuzzy sets are based on linguistic description, therefore they don't need to the mathematical model of the investigated systems. The proposed method is very suitable to nonlinear and time variant loads. The controller is robust, reliable and it has a smooth response. Also transient response of method is much better than the other classical methods. The simulation results confirm the suitable performance of the filter using this control method.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.182-187
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• 2014

We propose nonlinear GMM-based transformation functions in an attempt to deal with the over-smoothing effects of linear transformation for voice processing. The proposed methods adopt RBF networks as a local transformation function to overcome the drawbacks of global nonlinear transformation functions. In order to obtain high-quality modifications of speech signals, our voice conversion is implemented using the Harmonic plus Noise Model analysis/synthesis framework. Experimental results are reported on the English corpus, MOCHA-TIMIT.

• Journal of Biomedical Engineering Research
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• v.11 no.1
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• pp.179-186
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• 1990

A numerical analysis of crutch walking cycle has been performed to determine the transmissibility of a single-degree-of-freedom crutch system when a non-harmonic periodic forcing function is acting on the spring-damping-mass system. The results indicate that the damping factor which can reduce the forces transmitted to the human body plays an important role. In crutch walking, the stride angle of dynamic crutches must be limited for the comfortable walking.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.2
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• pp.313-317
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• 2011

In this article, we consider an unbounded minimal graph $M{\subset}R^3$ which is contained in a slab. Assume that ${\partial}M$ consists of two Jordan curves lying in parallel planes, which is symmetric with the reflection under a plane. If the asymptotic behavior of M is also symmetric in some sense, then we prove that the minimal graph is itself symmetric along the same plane.

• Communications of the Korean Mathematical Society
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• v.34 no.1
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• pp.239-251
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• 2019

In this paper we introduce a new formulation of symmetric homogeneous bivariate means that depends on the variation of a given continuous strictly increasing function on (0, ${\infty}$). It turns out that this class of means includes a lot of known bivariate means among them the arithmetic mean, the harmonic mean, the geometric mean, the logarithmic mean as well as the first and second Seiffert means. Using this new formulation we introduce a lot of new bivariate means and derive some mean-inequalities.

• Journal of Power Electronics
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• v.15 no.3
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• pp.712-720
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• 2015

A model predictive current control (MPCC) method that does not employ a cost function is proposed. The MPCC method can decrease common-mode voltages in loads fed by three-phase voltage-source inverters. Only non-zero-voltage vectors are considered as finite control elements to regulate load currents and decrease common-mode voltages. Furthermore, the three-phase future reference voltage vector is calculated on the basis of an inverse dynamics model, and the location of the one-step future voltage vector is determined at every sampling period. Given this location, a non-zero optimal future voltage vector is directly determined without repeatedly calculating the cost values obtained by each voltage vector through a cost function. Without utilizing the zero-voltage vectors, the proposed MPCC method can restrict the common-mode voltage within ± V_dc/6, whereas the common-mode voltages of the conventional MPCC method vary within ± V_dc/2. The performance of the proposed method with the reduced common-mode voltage and no cost function is evaluated in terms of the total harmonic distortions and current errors of the load currents. Simulation and experimental results are presented to verify the effectiveness of the proposed method operated without a cost function, which can reduce the common-mode voltage.

• Phonetics and Speech Sciences
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• v.1 no.2
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• pp.37-42
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• 2009

The purpose of the present study was to determine the effect of the management program known as vocal function exercise (VFE) on voice quality. Typical VFE was modified and applied to patients with vocal nodules by controlling intensity of voice and relieving the vocal fold to solve hyperfunctional problems in VFE. Eight female subjects aged between 28 and 54 who had been diagnosed with vocal nodules took part in the study. The patients performed VFEs once a week for eight weeks. Vocal function exercises consist of voice hygiene, respiratory training, phonation training, and glide training. The subjects' voices were analyzed pre and post therapy on the aspects of acoustics, maximum phonation time (MPT), GRBAS, and voice handicap index (VHI). As a result, it was found that fundamental frequency ($F_o$) was significant increased, shimmer decreased remarkably and that noise to harmonic ratio (NHR) lowered obviously in the acoustic parameter. In addition, MPT was increased significantly. The scale of GRBAS indicated significant improvement in grade, roughness, and strained voice. VHI indicated significant improvement in an emotional part. In conclusion, VFE was effective in improving voice quality for patients with vocal nodules.