• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1073-1078
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• 2012

This paper presented the extraction solution for the coupling coefficient at the magnetically coupled wireless power transmission(WPT) system through the analysis of its equivalent circuit considering the loss. The conventional extraction solution using coupled mode theory is generalized employing the extracted solution considering the load resistance. Consequently, the measuring process of extracting coupling coefficient becomes convenient since the even/odd mode analysis is not necessary. Furthermore, the coupling coefficient obtained from the induced extraction method was in excellent agreement with the coupling coefficient obtained using the ratio of magnetic flux passing through the two loops. The extraction of the accurate coupling coefficient at the magnetically coupled WPT is an essential work to analyze and optimize the WPT system.

• International Journal of Ocean System Engineering
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• v.1 no.2
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• pp.76-88
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• 2011

The present study deals with the hydroelastic vibration analysis of structures in contact with fluid via coupled fluid-structure interaction (FSI) embedded with a finite element method (FEM) such that a structure displacement formulation is coupled with a fluid pressure-displacement formulation. For the preliminary study and validation of FEM based coupled FSI analysis, hydroelastic vibration characteristics of a rectangular plate in contact with fluid are first compared with the elastic vibration in terms of boundary condition and mode frequency. Numerical results from coupled FSI analysis have been shown to be rational and accurate, compared to energy method based theoretical solutions and experimental results. The effect of free surface on the vibration mode is numerically studied by changing the submerged depth of a rectangular plate. As a practical application, the hull structural vibration of 4,000 twenty-foot equivalent units (TEU) container ship is considered. Hydroelastic results of the ship hull structure are compared with those obtained from the elastic condition.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.377-381
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• 2014

Coupled guided modes, proposed in various modified hollow hexagonal cavities each attached internally to a hexagon, were demonstrated by investigating the laser oscillations in semiconductor cavities. The mode spacing between two adjacent lasing peaks decreased as the size of the internal hexagon increased, due to the increased round-trip length of the coupled guided modes. The linear dependency of the inverse mode spacing to the calculated round-trip length strongly confirmed the lasing of the coupled guided modes. The proposed modes in common-sized external cavities showed resonance structure that could be adjusted widely by controlling the size of the internal hexagon.

• The Journal of the Acoustical Society of Korea
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• v.6 no.4
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• pp.64-73
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• 1987

Low frequency sound propagation in a range-dependent shallow water environment of the Korea Strait has been studied by using the adiabatic coupled mode, ADIAB. The range-dependent environment is unique in terms of horizontal variations of sound velocity profiles, sediment thickness and attenuation coefficients and water depths. For shallow source and receiver depths, the most important mechanism involved in the propagation loss is the depth changing character of mode functions that strongly depends on the local sound velocity profile. Application of the adiabatic coupled mode theory to shallow water environment is reasonable when higher modes are attenuated due to bottom interaction effects. Underwater sound propagation in a range-dependent shallow-water environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.5
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• pp.603-613
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• 1998

Resonant characteristic of Whispering modes(W. G. mode) on a dielectric disk resonator is influenced by an external circuit that is placed near the disk to excite this type of modes. In order to evaluate this phenomenon, we divide the disk resonator as two parts; a coupling part in which the mode coupling occurs and on uncoupled region. In the coupled part, we regard the part of the disk as a curved waveguide which is loaded with matched circuit, and derive a coupled mode equation for nonparallel dielectric waveguides. From the coupled mode equation, we calculate coupling coefficients and a coupled electromagnetic field. By using the complex coupling coefficients, we can calculate power transfer. We also calculate a resonant frequency in consideration of the mode coupling phenomenon. The calculated resonance frequence is confirmed by experiment for the resonance characteristics. As the results, it is found that the discrepancy between the theoretical and the experimental resonance frequencies is about 1.28% and the discrepancy between theory and experiment of FSR is about 0.6%.

• Membrane Journal
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• v.21 no.3
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• pp.263-269
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• 2011

In the operation of submerged membrane-coupled sequencing batch reactor, the effect of filling step on the removal efficiency and filtration performance were investigated. Two sets of operation modes, the filling step located in the beginning of aerobic step (Mode-1) and the beginning of anoxic step (Mode-2), during 89 days were conducted. There was no wide difference in the COD removal and filtration performance between two sets of operation modes. But in the removal efficiency of nutrients (total nitrogen and total phosphorous), Mode-2 was more effective than Mode-1. In the case of Mode-2, average removal efficiencies of COD, total nitrogen, and total phosphorous were 99.1, 73.3, and 77.3%, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.104-111
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• 2000

It is very difficult to maintain the desired tank level without any overflow or any shortage in a dangerous shemical plant and in a cooling one. Futhermore, because its dynamics are very complicate and nonlinear, it is impossible to realize the precise control using the accurate mathematical model which can be applied to the various peration modes. Nonetheless, the sliding mode controller(SMC) is known as having the robust variable structures for the nonlinear control system with the parametric perturbations and with the rapid disturbances. But the adaptive tuning algorithms for their parameters are not satisfactory. Therefore, in this paper, a Real Variable Elitist Genetic Algorithm based Sliding Mode Controller (RVEGA SMC) for the precise control of the coupled tank level was tried. The SMC's switching parameters were optimized easily and rapidly by RVEGA. The simulation results showed that the tank level could be satisfactorily controlled without and overshoot and any steady-state error by the proposed RVEGA SMC.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.239-244
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• 2002

Even though, tanks are used at the many industry plants, it is very difficult to control the tank level without any overflow and shortage; moreover, cause of its complication of dynamics and nonlinearity, it's impossible to realize the accurate control using the mathematical model which can be applied to the various operation modes. However, the sliding mode controller(SMC) is known as having the robust variable structures for the nonlinear control systems with the parametric perturbations and with the sudden disturbances, but the auto-tuning of parameters was a problem. Therefore, in this paper, a Genetic Algorithm based Sliding Mode Controller (GA-SMC) for the precise control of the coupled tank level was tried. GA optimized the SMCs switching parameters easily and rapidly. The simulation results are shown that the tank level could be satisfactorily controlled with less overshoot and steady-stale error by the proposed GA-SMC.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.1
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• pp.20-23
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• 2004

In this paper, the emission properties of electrodeless fluorescent lamp were discussed using the inductively coupled plasma. To transmit the electromagnetic energy into the chamber, a RF power of 13.56 [MHz] was applied to the antenna and considering the Ar gas pressure and the RF electric power change, the emission spectrum, Ar I line, luminance were investigated. At this time, the input parameter for ICP RF plasma, Ar gas pressure and RF power were applied in the range of 10∼60 [mTorr], 10∼300 [W], respectively. From emission intensity and lumnance intensity results, the mode transition from E-mode to H-mode was observed. This implies that this method can be used to find an optimal RF power for efficient light illumination in an electrodeless fluorescent lamp.

• Korean Journal of Optics and Photonics
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• v.25 no.1
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• pp.44-49
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• 2014

We have analyzed the amplification of a signal wave in the optical parametric interactions of the pump, signal, and idler waves in planar waveguides, with the pump wave being Cerenkov radiation. Based on the coupled-mode theory, we have derived the first-order coupled-mode differential equations for no pump depletion. The equations can easily be solved numerically. The approximate analytical and numerical solutions of the equations show that the signal wave can be amplified parametrically.