• International Journal of Control, Automation, and Systems
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• v.5 no.1
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• pp.1-7
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• 2007

In this paper, the necessary and sufficient conditions for strict positive realness of the rational transfer functions directly from basic definitions in the frequency domain are studied. A new frequency domain approach is used to check if a rational transfer function is a strictly positive real or not. This approach is based on the Taylor expansion and the Maximum Modulus Principle which are the fundamental tools in the complex functions analysis. Four related common statements in the strict positive realness literature which is appeared in the control theory are discussed. The drawback of these common statements is analyzed through some counter examples. Moreover a new necessary condition for strict positive realness is obtained from high frequency behavior of the Nyquist diagram of the transfer function. Finally a more simplified and completed conditions for strict positive realness of single-input single-output linear time-invariant systems are presented based on the complex functions analysis approach.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1082-1089
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• 2017

Negative output elementary super lift Luo converter (NOESLLC), which has the significant advantages including high-voltage transfer gain, high efficiency, high power density, and reduced output voltage/inductor current ripples when compared to the traditional DC-DC converters, is an attractive DC-DC converter for the field of negative DC voltage applications. In this study, in consideration of the voltage across the energy transferring capacitor changing abruptly at the beginning of each switching cycle, the improved averaged model of the NOESLLC operating in continuous conduction mode (CCM) is established. The improved DC model and transfer functions of the system are derived and analyzed. The current mode control is applied for this NOESLLC. The results from the theoretical calculations, the PSIM simulations and the circuit experiments show that the improved DC model and transfer functions here are more effective than the existed ones of the NOESLLC to describe its real dynamical behaviors.

• Journal of Drive and Control
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• v.19 no.4
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• pp.77-84
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• 2022

The aims of this study was to estimate transfer force delivered to cone crusher housing and contribution of force transmission. The rock crushing condition caused vibrations in the cone crusher housing, which were experimentally measured, and frequency response functions (FRF) were also found through modal impact tests. Vibration data and frequency response functions were applied to the transfer path analysis (TPA) model. Next, transfer forces delivered to the cone crusher housing were quantified via the TPA method. Contribution of force transfer was also analyzed based on force estimation results. Finally, this study describes basic concepts and components of the TPA method and reviews its applicability to rotating machinery that experiences impact vibrations and forces.

• Transactions on Control, Automation and Systems Engineering
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• v.1 no.1
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• pp.50-53
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• 1999

It has been pointed out in the literature that the Routh approximation method for order reduction has limitations in treating transfer functions with the denominator-numerator order difference not equal to one. The purpose of this paper is to present a new algorithm based on the Routh approximation method that can be applied to general rational transfer functions, yield ing reduced models with arbitrary order.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.161-168
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• 2020

Local decentralization is a rational allocation of power and responsibilities between the state and local governments, but it is not just a transfer of administrative affairs and transfer of funds. In order to look at the task of moving administrative affairs to the districts, this paper first considered the relevant prior study. Next, we looked at the assessment of the level of function transfer and direction of transfer for government employees. Finally, the task for the transfer of functions has been drawn. Revitalizing functions or affair transfers requires the president's firm will and continued support, efforts to divide roles between central and local governments, increased responsibilities of local governments, revitalizing civic participation and establishing democracy. In addition, in order to expand the function transfer problem, the affair allocation system must be newly established. The discussion of such a system should take into account the issue of regional equity as well as financial transfers. Localization through transfer of functions requires, among other things, a change in perception of the relevant groups. Local decentralization requires long-term time and the participation and cooperation of not only the central but also related stakeholders are important, as seen in existing studies and in the nation's experience.

• Transactions of the Korean Society of Mechanical Engineers
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• v.3 no.3
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• pp.91-97
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• 1979

Boundary layer equations (partial differential equations) can be transformed to ordinary diffential equations with constant coeffieients in terms of similarity transformed to ordinary differential equations with constant coeffieients in terms of similarity transformations in the heat tranfer analysis on the surface of any axiaymmetric boiles. The azimuth functions can not be uniquely determined because of the singular behavior at the stagnation point(X=0.deg.).In spite of the azimuth functions behaving singularly, many of researchers have analyzed the heat transfer problem on a horizontal chlinder or a sphere, supposing the set of solutions( $H_{1}$ & G$_{1}$) of being yieled from the simple differential equation to be unique solution of therazimuth functions. In order to ascertain whether mathematical incompatibility as mentioned above can be admitted in the viewpoint of enginerring or not, condensation heat transfer coefficients on a sphere are computed for all azimuth functions( $H_{1}$ G$_{1}$ & $H_{2}$ G$_{2}$) and comparisons with the experimental result are discussed.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.4
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• pp.38-43
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• 2011

For the efficient and safe operation of nuclear power plant, evaluating quantitatively aging phenomenon of major components is necessary. Especially, typical aging parameters such as stresses and cumulative usage factors should be determined accurately to manage the lifetime of the plant facility. The 3-D finite element(FE) model is generated to calculate the aging parameters. Mechanical and thermal transfer functions called Green's functions are developed for the FE model with standard step input. The stress results estimated from transfer functions are verified by comparing with 3-D FE analyses results. Lastly, we suggest an effective fatigue evaluation methodology by using the transfer functions. The usefulness of the proposed fatigue evaluation methodology can be maximized by combining it with an on-line monitoring system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.26.1-26
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• 2001

In this paper, we will expand and generalize the orthogonal functions as basis functions for dynamical system representations. The orthogonal functions can be considered as generalizations of, for example, the pulse functions, Laguerre functions, and Kautz functions, and give rise to an alternative series expansion of rational transfer functions. It is shown row we can exploit these generalized basis functions to increase the speed of convergence in a series expansion. The set of Kautz functions is discussed in detail and, using the power-series equivalence, the truncation error is obtained. And so we will present the influence of noises to use Kautz function on the identification accuracy.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.10
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• pp.900-906
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• 2010

This note proposes vibration-free motor control through modified LQG/LTR methodology. A conventional LQG/LTR method is a design tool in the frequency domain. However, unlike the conventional one, the proposed one is a time response based design method. This feature is firstly designed by parameterized settling time control gain through the target loop design procedure and the feature is secondly realized by loop transfer recovery. In order to show convergence to the target loop transfer functions, asymptotic behaviors of the open and the closed loop transfer functions are shown. At the conclusion, it is verified that the proposed method is robustly stable to parametric uncertainties through ${\mu}$-plot.

• Journal of ILASS-Korea
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• v.26 no.4
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• pp.182-188
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• 2021

In this paper, using a transfer function-based analytical model, major factors influencing the acoustics and combustion instability in a two-stage duct system composed of a nozzle and a combustor were derived and their quantitative effects were evaluated. From the acoustic analysis, it was confirmed that the change in reflection coefficient and mean flow could have a great influence on the instability growth rate, and the area ratio and speed of sound ratio between the nozzle and the combustor are also key parameters to determine combustion instability as well as flame transfer functions.