• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.143-152
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• 2010

Based on the Exp-function method and a suitable transformation, new generalized solitonary solutions including free parameters of the MDI and Sawada-Kotera equations with variable coefficients are obtained, form which solitary wave solutions and periodic solutions including some known solutions reported in open literature are derived as special cases. The free parameters in the obtained generalized solitonary solutions might imply some meaningful results in the physical models. It is shown that the Exp-function method provides a very effective and important new method for nonlinear evolution equations with variable coefficients.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.4
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• pp.594-606
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• 1999

The electromagnetic scattering characteristics by a periodic strip grating on a grounded dielectric slab for TE polarization case is examined from the viewpoints of both the reflection grating and the leaky wave antenna problems. Numerical results for two kinds of Bragg blazing (resonance type and non-resonance type) phenomena are given and some discussions on the properties such as complex propagation constants, scattering characteristics, and distributions of strip current density are presented.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.3
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• pp.78-84
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• 1994

The location of periodic noises in phase of AC power wave reveals to be specific according to the noise kinds which can be generally classified into modulation and baseband types in DLC. The former noise type has constant noise phase which is originated from switching mode power supplies and the latter normally caused from thyristor circuit of low switching frequency is compared to be more dispersive than the other.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.11
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• pp.88-96
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• 1996

Periodically slotted dielectricalloy filled parallel-plate waveguide as a leaky wave antenna is designed and fabricated at the center frequency of 10.0GHz. The antenna was fed by use of a hog-horn structure. The hog-horn and the two side walls and the lower plate of parallel-plate waveguide were fabricated form duralumin. The upper plate of parallel-plate waveguide with 48 periodic slots was made of copper plate of 1mm thickness. The dielectric material inside the parallel-plate waveguide was chosen to be paraffin. The experimental radiation pattern for the fbricated antenna was compared with the theoretical results for the finite periodic structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.451-461
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• 2001

We present a simple design method of velocity-matched traveling-wave (TW) electrode with periodic capacitive loads. Once matching impedance and optical phase velocity are defined, the width and separation of coplanarstrip (CPS) and the magnitude and period of capacitive load are determined analytically. Calculation results of velocity-matched TW electrodes on GaAs substrates show bandwidths of more than 100 GHz.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1440-1448
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• 2004

Multiple solutions in natural convection of air (Pr=0.7) between two horizontal walls with mean temperature difference and the same periodic nob-uniformities are investigated. An analytical solution is found for small Rayleigh number, and the general solution is investigated by using a numerical method. In the conduction-dominated regime, two upright cells are formed between two walls over one wave length. When the wave number is small, the flow becomes unstable with increase of the Rayleigh number, and multicellular convection occurs above a critical Rayleigh number. The multicellular flows at high Rayleigh numbers consist of approximately square-shape cells. And several kinds of multiple flows classified by the number of cells are found.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.12
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• pp.1040-1045
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• 2016

An inventory control system was developed for multiproduct batch plants with an arbitrary number of batch processes and storage units. Customer orders are received by the plant at intervals and in quantities that are subject to random fluctuations. The objective of the plant operation is to minimize the total cost while maintaining inventory levels within the storage or warehouse capacity by adjusting the startup times, the quantities of raw material orders, and production batch sizes. An adaptive model-based control algorithm was developed that uses a periodic square wave model to represent the flows of material between the processes and the storage units. The effectiveness of this approach was demonstrated by performing simulations.

• Current Optics and Photonics
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• v.7 no.5
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• pp.562-568
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• 2023

We designed a combined nanostructure of inverted pyramidal pits and nanoparticles, which can obtain much stronger field enhancement than traditional periodic pits or nanoparticles. The field enhancement |E|/|E₀| is greater than 10 in a large area at 750-820 nm in incident wavelength. |E_max|/|E₀| is greater than 60. Moreover, the hot spot is obtained outside the pits instead of localized inside them, which is beneficial for experiments such as surface-enhanced Raman scattering. The relations between resonant wavelength and structural parameters are investigated. The resonant wavelength shows a linear dependence on the structure's period, which provides a direct way to tune the resonant wavelength. The excitation of a propagating surface plasmon on the periodic structure's surface, a localized surface plasmon of nanoparticles, and a standing-wave effect contribute to the enhancement.

• Earthquakes and Structures
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• v.24 no.4
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• pp.259-274
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• 2023

In this paper, mechanical properties of periodic foundation made of concrete and rubber are investigated by a parametric study using the finite element method (FEM). Periodic foundation is a special type of seismic isolation foundation used in civil engineering, which is inspired by the meso-scale structure of phononic crystals in solid-state physics. This type of foundation is capable of reducing the seismic wave propagating though the foundation, therefore providing additional protection for the structures. In the FEM analysis, layered periodic foundation is frequently modelled due to its simplicity in numerical modeling. However, the isolation effect of periodic foundation on nuclear power plant has not been fully discussed to the best knowledge of authors. In this work, we construct four numerical models of nuclear power plant with different foundations to investigate the seismic isolation effects of periodic foundations. The results show that the layered periodic foundation can increase the natural period of the nuclear power plant like traditional base isolation systems, which is beneficial to the structures. In addition, the seismic response of the nuclear power plant can also be effectively reduced in both vertical and horizontal directions when the frequencies of the incident waves fall into some specific frequency bandgaps of the periodic foundation. Furthermore, it is demonstrated that the layered periodic foundation can reduce the amplitude of the floor response spectrum, which plays an important role in the protection of the equipment.

• The Pure and Applied Mathematics
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• v.9 no.1
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• pp.19-30
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• 2002

We consider one class of bursting oscillation models, that is square-wave burster. One of the interesting features of these models is that periodic bursting solution need not to be unique or stable for arbitrarily small values of a singular perturbation parameter $\epsilon$. Recent results show that the bursting solution is uniquely determined and stable for most of the ranges of the small parameter $\epsilon$. In this paper, we present a condition of uniqueness and stability of periodic bursting solutions for all sufficiently small values of $\epsilon$ > 0.