• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.141-144
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• 1992

A Generator Control Systems data is complcated by the existence of a wide variety of Control system types and by the fact that the values of key parameters may depend upon the generator types and operating conditions. This paper decribes the typical value determination methods for generator control systems using response ratio test and step response test. It can be a practical way to provide and verify data for real power system analysis.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.3-10
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• 2006

In this study, the of MBBR(moving bed biofilm reactor) process for Phosphorus Removal efficiency depending on seasons and the factors affecting phosphorus removal efficiency in the process is evaluated. As a result of experiment, T-P removal efficiency has its highest value in winter, (80.8%). and T-P removal efficiency has its lowest value in autumn, (49%). Optimum SRT for Phosphorus Removal revealed is about 8.8 days and process performs more efficiently as the temperature decreases. It is accepted that nitrate to anaerobic zone is affecting the Phosphorus removal process. With increasing the organic loading rate, Phosphorus removal efficiency also increases. Also, an experiment has been conducted to find out the highest efficiency according to Media existence and it has revealed that Media addition provides better phosphate removal.

• Korean Journal of Mathematics
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• v.20 no.4
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• pp.507-515
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• 2012

We investigate the number of the solutions for the elliptic boundary value problem. We obtain a theorem which shows the existence of six weak solutions for the elliptic problem with jumping nonlinearity crossing three eigenvalues. We get this result by using the geometric mapping defined on the finite dimensional subspace. We use the contraction mapping principle to reduce the problem on the infinite dimensional space to that on the finite dimensional subspace. We construct a three dimensional subspace with three axis spanned by three eigenvalues and a mapping from the finite dimensional subspace to the one dimensional subspace.

• Journal of applied mathematics & informatics
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• v.27 no.3_4
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• pp.501-515
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• 2009

A second order nonlinear ordinary differential equation is obtained by solving the initial-boundary value problem of a class of elas-todynamics equations, which models the radially symmetric motion of a incompressible hyper-elastic solid sphere under a suddenly applied surface tensile load. Some new conclusions are presented. All existence conditions of nonzero solutions of the ordinary differential equation, which describes cavity formation and motion in the interior of the sphere, are presented. It is proved that the differential equation has singular periodic solutions only when the surface tensile load exceeds a critical value, in this case, a cavity would form in the interior of the sphere and the motion of the cavity with time would present a class of singular periodic oscillations, otherwise, the sphere remains a solid one. To better understand the results obtained in this paper, the modified Varga material is considered simultaneously as an example, and numerical simulations are given.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.2
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• pp.176-181
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• 2004

This paper introduces a Web site login system that uses user's native voice to improve the bother of remembering the ID and password in order to login the Web site. The DTW method that applies fuzzy inference is used as the speaker recognition algorithm. We get the ACC(Average Cepstrum Coefficient) membership function by each degree, by using the LPC that models the vocal chords, to block the recorded voice that is problem for the speaker recognition. We infer the existence of the recorded voice by setting on the basis of the number of zeros that is the value of the ACC membership function, and on the basis of the average value of the ACC membership function. We experiment the six Web sites for the six subjects and get the result that protects the recorded voice about 98% that is recorded by the digital recorder.

• Journal of the Korean Society for Library and Information Science
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• v.1
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• pp.77-102
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• 1970

The writer discusses about the value of the two-volume Chuchih $Ch'unch\hat{e}ng$ in the Toyo Bunko in terms of its history and contents. The book is an incomplete reprint without preface. However, it has no error in its contents through the three elaborate revisions. The writer defines the book as a scientific and religious work. The author shows in the first volume his hypothesis, analysis, and conclusion, of the order of the things in the universe and in the second volume tries to prove the God's existence and Divine Providence. The proofs presented are related to the scientific thoughts of the West in the 17th century.

• Journal of the Korean Mathematical Society
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• v.49 no.4
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• pp.715-731
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• 2012

This paper considers the stability of positive steady-state solutions bifurcating from the trivial solution in a delayed Lotka-Volterra two-species predator-prey diffusion system with a discrete delay and subject to the homogeneous Dirichlet boundary conditions on a general bounded open spatial domain with smooth boundary. The existence, uniqueness and asymptotic expressions of small positive steady-sate solutions bifurcating from the trivial solution are given by using the implicit function theorem. By regarding the time delay as the bifurcation parameter and analyzing in detail the eigenvalue problems of system at the positive steady-state solutions, the asymptotic stability of bifurcating steady-state solutions is studied. It is demonstrated that the bifurcating steady-state solutions are asymptotically stable when the delay is less than a certain critical value and is unstable when the delay is greater than this critical value and the system under consideration can undergo a Hopf bifurcation at the bifurcating steady-state solutions when the delay crosses through a sequence of critical values.

• Journal of the Korean Mathematical Society
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• v.58 no.5
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• pp.1109-1129
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• 2021

This paper considers an anisotropic polytropic infiltration equation with a source term $$u_t={\sum\limits_{i=1}^{N}}{\frac{{\partial}}{{\partial}x_i}}\(a_1(x){\mid}u{\mid}^{{\alpha}_i}{\mid}u_{x_i}{\mid}^{p_i-2}u_{x_i}\)+f(x,t,u)$$, where p_i > 1, α_i > 0, a_i(x) ≥ 0. The existence of weak solution is proved by parabolically regularized method. Based on local integrability $u_{x_i}{\in}W_{loc}^{1,p_i}(\Omega)$, the stability of weak solutions is proved without boundary value condition by the weak characteristic function method. One of the essential characteristics of an anisotropic equation different from an isotropic equation is found originally.

• Nonlinear Functional Analysis and Applications
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• v.29 no.2
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• pp.527-543
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• 2024

In the realm of differential games and bioeconomic modeling, where intricate systems and multifaceted interactions abound, we explore the precision and efficiency of the Chebyshev Tau method (CTM). We begin with the Weierstrass Approximation Theorem, employing Chebyshev polynomials to pave the way for solving intricate bioeconomic differential games. Our case study revolves around a three-player bioeconomic differential game, unveiling a unique open-loop Nash equilibrium using Hamiltonians and the FilippovCesari existence theorem. We then transition to numerical implementation, employing CTM to resolve a Three-Point Boundary Value Problem (TPBVP) with varying degrees of approximation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.579-584
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• 2008

A novel nondestructive testing (NDT) system, which is able to detect a crack with high speed and high spatial resolution, is urgently required for inspecting small cracks on express train wheels. This paper proposes an improved signal processing circuits, which uses the multiple amplifying circuits and the crack indicating pulse output system of the previous scan-type magnetic camera. Hall sensors are arrayed linearly, and the wheel is rotated with static speed in the vertical direction to sensor array direction. Each Hall voltages are amplified, converted and immediately operated by using, amplifying circuits, analog-to-digital converters and $\mu$-processor, respectively. The operated results, ${\partial}V_H/{\partial}t$, are compared with a standard value, which indicates a crack existence. If the ${\partial}V_H/{\partial}t$ is larger than standard value, the pulse signal is output, and indicates the existence of crack. The effectiveness of the novel method was verified by examine using cracks on the wheel specimen model.