• 호남수학학술지
• /
• 제42권4호
• /
• pp.747-755
• /
• 2020

The mathematical proof for establishing some new inequalities involving arithmetic, geometric, harmonic means for the arguments lying on the paths of triangular wave function (linear) and new parabolic function (curved) over the interval (0, 1) are discussed. The results representing an extension as well as strengthening of Ky Fan Type inequalities.

• Geomechanics and Engineering
• /
• 제31권2호
• /
• pp.159-166
• /
• 2022

The model of two-dimensional plane waves is analyzed in a micropolar-thermoelastic solid with microtemperatures in the context of the three-phase-lag model, dual-phase-lag model, and the Green-Naghdi theory of type III. Harmonic wave analysis is used to hold the solution to the problem. Numerical results of the physical fields are visualized to show the effects of the gravity field, magnetic field, and viscosity. The expression for the field variables is obtained generally and represented graphically for a particular medium.

• Journal of electromagnetic engineering and science
• /
• 제6권2호
• /
• pp.98-102
• /
• 2006

In this paper, we have designed and fabricated the high power amplifier employing PBG(Photonic Band-Gap Structure) to improve the linearity of the amplifier in the millimeter wave band. The fabricated amplifier using MMIC(TGA1073G) has operated about 24 GHz band and the PBG has resulted in 35 dB suppression about 49 GHz where the second harmonic occurs due to the amplifier. As a result, the output power has been 24.43 dBm and 13.2 dBc of the IMD has been improved. Also, the PAE is obtained to 14.96 % of the amplifier employing the PBG structure in Ka band.

• 전기학회논문지
• /
• 제60권8호
• /
• pp.1566-1571
• /
• 2011

The objective of this paper is to present a quantitative analysis leading to the assessment of optimum terminating impedances in the design of active frequency multipliers. A brief analysis of the basic principal of the GaAs FET frequency multiplier is presented. The analysis is outlined in bias optimization and drive power determination. Utilizing the equivalent circuit model of GaAs FET, we have simulated the optimized load impedance for the maximum output of the active frequency multipliers. The C-class and reverse C-class frequency doublers have been fabricated and the load impedances have been measured. The experimental results are in good agreement with the estimated results in the simulation with the accuracy of 90%.

• 대한수학회지
• /
• 제38권2호
• /
• pp.227-274
• /
• 2001

In this paper we intended to discuss the following topics: (1) Notation, generalities, Markov processes. The close relationship between (generators of) Markov processes and the martingale problem is exhibited. A link between the Korovkin property and generators of Feller semigroups is established. (2) Feynman-Kac semigroups: 0-order regular perturbations, pinned Markov measures. A basic representation via distributions of Markov processes is depicted. (3) Dirichlet semigroups: 0-order singular perturbations, harmonic functions, multiplicative functionals. Here a representation theorem of solutions to the heat equation is depicted in terms of the distributions of the underlying Markov process and a suitable stopping time. (4) Sets of finite capacity, wave operators, and related results. In this section a number of results are presented concerning the completeness of scattering systems (and its spectral consequences). (5) Some (abstract) problems related to Neumann semigroups: 1st order perturbations. In this section some rather abstract problems are presented, which lie on the borderline between first order perturbations together with their boundary limits (Neumann type boundary conditions and) and reflected Markov processes.

• Journal of information and communication convergence engineering
• /
• 제12권1호
• /
• pp.39-45
• /
• 2014

A numerical method for solving Hamiltonian equations is said to be symplectic if it preserves the symplectic structure associated with the equations. Various symplectic methods are widely used in many fields of science and technology. A symplectic method preserves an approximate Hamiltonian perturbed from the original Hamiltonian. It theoretically supports the effectiveness of symplectic methods for long-term integration. Although it is also related to long-term integration, numerical stability of symplectic methods have received little attention. In this paper, we consider explicit symplectic methods defined for Hamiltonian equations with Hamiltonians of the special form, and study their numerical stability using the harmonic oscillator as a test equation. We propose a new stability criterion and clarify the stability of some existing methods that are visually based on the criterion. We also derive a new method that is better than the existing methods with respect to a Courant-Friedrichs-Lewy condition for hyperbolic equations; this new method is tested through a numerical experiment with a nonlinear wave equation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
• /
• pp.85-88
• /
• 2000

This paper was development a discharge lamp ballast in order to wave improvement of high power factor and high efficiency. The discharge lamp ballast consists of a power factor correction circuit and a correction circuit on switching frequency of inverter. Instead of passive power factor circuit, active power factor circuit is adopted. Because it has the advantage of size, weight, total harmonic distortion, out DC voltage regulation, and power factor. The power factor circuit with MG34262 is controlled by variable frequency discontinuous mode. Results experiments, discharge lamp ballast is showed to have excellent for the proposed electronic ballast's operation and characteristics.

• 한국음향학회:학술대회논문집
• /
• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
• /
• pp.303-306
• /
• 1999

The paper describes a theoretical study on the speed of the torsional elastic waves propagating in a circular cylinder whose outer radius varies periodically as a harmonic function of the axial coordinate. The approximate solution for the phase speed has been obtained using the perturbation technique for sinusoidal modulation of small amplitude. It is shown that the wave speed in the cylinder with a corrugated outer surface is less than that in a smooth cylinder by the square of the amplitude of the surface perturbation. This theoretical prediction agrees reasonably with an experimental observation reported earlier. It is also shown that the wave speed reduction due to the surface corrugation becomes larger for a thinner cylinder and for a bigger density of corrugation.

• 한국소음진동공학회논문집
• /
• 제11권4호
• /
• pp.65-70
• /
• 2001

An investigation into asymmetric vibrations of a clamped circular place under a harmonic excitation is made. We examine a primary resonance. in which the frequency of excitation is near the natural frequency of an asymmetric mode of the plate. We found not only a response haying the form of standing wave but also one having the form of traveling wave, which was not observed by Sridhar, Mook and ${Nayfeh}^{(1)}$

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2000년도 추계학술대회 논문집
• /
• pp.184-188
• /
• 2000

The improved Green integral equation of overdetermined type applied to the radiation problem for an oscillating cylinder in the presence of weak current is presented. A two-dimensional Green function for the weak current is also presented. The present numerical solution of the Improved Green integral equation by the B-spline higher order Kelvin panel method is shown to be free of irregular frequencies which are present in the usual Green integral equation.