• Bulletin of the Korean Mathematical Society
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• 제55권1호
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• pp.165-173
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• 2018

In this paper we obtain the bounds of the third Hankel determinants for the classes $\mathcal{S}^*({\alpha})$ of starlike functions of order ${\alpha}$ and $\mathcal{K}({\alpha}$) of convex functions of order ${\alpha}$. Moreover,we derive the sharp bounds for functions in these classes which are additionally 2-fold or 3-fold symmetric.

• Journal of the Korean Society for Precision Engineering
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• 제4권3호
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• pp.35-43
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• 1987

A new analytic method for the identification of process control system is presented. A second and a third order transfer function are considered as the estimated model function. For the second order transfer function, the new method is compared with the exisiting ones, simulation results show that the new method is superior to the existing ones. And also, In case of the third order transfer function which is difficult to analyze mathematically, system identification is tried.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제5권4호
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• pp.653-660
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• 2001

In this paper, we designed 2303.15MHz frequency synthesizer for the purpose of the phase noise prediction. For the modeling of phase noise generated in the designed system through introducing the noise-modeling method suggested by Lascari we analyzed a variation of phase noise as according as that of offset frequency. Especially, for the third-order system of the PLL among some kinds of phase noise generated from VCO we analyzed the aspect of 1/f-noise appearing troubles in the low frequency band. Since it is difficult to analyze mathematically 1/f-noise in the third-order system of the PLL, introducing the concept of pseudo-damping factor has made an ease of the access of the 1/f-noise variance. we showed a numerical formula of 1/f-noise variance in the third-order system of the PLL which is compared with that of 1/f-noise variance in the second-order system of the PLL. As a result, In case of txco we found the reduce rapidly along the offset frequency after passed through that phase-noise was -160dBc/Hz before passed through a loop at 10kHz offset frequency and -162.6705dBc/kHz after passed through the loop, -180dBc/Hz at 100kHz offset frequency and -560dBc/kHz after passed through the loop. We can notice that the variance of third-order system more occurs (or the variance of second-order system in connection with noise bandwidth and variance factor of second-order and third-order system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제9권2호
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• pp.229-238
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• 1997

A third-order simulation model of VM heat pumps has been developed. This model allows consideration of the major losses such as heat conduction losses through regenerators and displacers, pumping losses and wall-to-gas heat transfer losses in working volumes, in addition to the heat exchanger and regenerator losses. The working volume was divided into 12 control volumes and conservation equations of mass and energy were applied to each control volume. Pressure drop was considered in regenerators only. Thermodynamic behavior of working fluid in a VM heat pump was investigated and effects of major losses on the performance of a VM heat pump were shown.

• Kyungpook Mathematical Journal
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• 제57권4호
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• pp.651-665
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• 2017

Some computational fluid dynamics problems concerning the thin films flow of viscous fluid with a free surface and draining or coating fluid-flow problems can be delineated by third-order ordinary differential equations. In this paper, the aim is to introduce the numerical solutions of the boundary value problems of such equations by variational iteration method. In this paper, it is shown that the third-order boundary value problems can be written as a system of integral equations, which can be solved by using the variational iteration method. These solutions are gleaned in terms of convergent series. Numerical examples are given to depict the method and their convergence.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.907-910
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• 2001

In this paper, we address a new time delay estimation method using third-order statistics and subband adaptive filtering to improve the accuracy of target detection for acoustic backscattered signals in a noise interference environment. Each reference and primary signals are decorrelated using the multiresolution analysis framework through a M-band discrete wavelet transform(M-DWT). Then noise effect can be reduced. Here, time delays are estimated iteratively in each subband using two different adaptation mechanisms that minimize the mean squared error (MSE) between the references and primary signal. More specifically, third-order cumulants and projection cross-correlation(PCC) criterion are utilized to achieve an effective SNR improvement for the time delay estimation.

• Journal of the Korean Mathematical Society
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• 제52권1호
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• pp.23-41
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• 2015

We present a semilocal convergence analysis of a third order method for approximating a locally unique solution of an equation in a Banach space setting. Recently, this method was studied by Chun, Stanica and Neta. These authors extended earlier results by Kou, Li and others. Our convergence analysis extends the applicability of these methods under less computational cost and weaker convergence criteria. Numerical examples are also presented to show that the earlier results cannot apply to solve these equations.

• Korean Journal of Optics and Photonics
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• 제7권4호
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• pp.305-313
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• 1996

Lens design method by using equivalent lenses was already introduced, but the method has a limitaion that all lenses should be in the air. Therefore, we often get improper solution in designing cemented lenses. In this study, the lens conversion from thick lens to equivalent lens and its reversal was generalized without any preconditions, and the third order aberration fomulrae were derived for the generalized equivalent lens system. The generalized equivalent lens conversion were applied to typical cemented doublet and triplet, and they show that the third order aberrations of the generalized equivalent lenses have better agreements with their corresponding thick lenses than the previous conversion method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• 제50권6호
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• pp.275-278
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• 2001

This paper presents an algorithm for detecting current transformer (CT) saturation. At the instants of beginning (or end) of saturation, as a magnetizing inductance of the core is changed significantly, the shapes of the secondary current are also changed significantly though secondary currents are continuous the instants. At the instants, the second-order of third-order difference of the secondary current has big values. Thus, the third difference of the current is used to detect the beginning/end of CT saturation in this paper. If the magnitude of third-order difference of the secondary current is larger than a threshold value, the CT begins of ends saturation at the instants. The proposed detection method is unaffected by the amount of residual flux. The results of various tests with residual flux from -80% to +80% indicate satisfactory performance of the method.

• Journal of applied mathematics & informatics
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• 제29권1_2호
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• pp.417-426
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• 2011

This paper is concerned with the existence of monotone positive solutions for a class of nonlinear third-order three-point boundary value problem. By applying iterative techniques, we not only obtain the existence of monotone positive solutions, but also establish iterative schemes for approximating the solutions. An example is also included to illustrate the importance of the results obtained.