• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.7
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• pp.28-34
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• 2011

Radiation characteristics of a dual-mode inductor loaded patch antenna using zeroth order resonance and half wavelength resonance are investigated. The isolation between two radiation patterns from the two different modes is improved by increasing the forward radiation and decreasing the horizontal radiation of half wavelength resonance mode. The frequency difference between the two resonant frequencies increases as the dielectric constant of the antenna substrate decreases and the operating frequency increases.

• Journal of Mechanical Science and Technology
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• v.18 no.3
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• pp.347-356
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• 2004

The flexural vibration characteristics of a sandwich beam system with a partially inserted viscoelastic layer were quantitatively studied using the finite element analysis in combination with the sine-sweep experiment. Asymmetric mode shapes of the flexural vibration were visualized by holographic interferometry, which agreed with those obtained by the finite element simulation. Effects of the length and the thickness of the partial viscoelastic layer on the system loss factor (η$\_$s/) and resonant frequency (f$\_$r/) were significantly large for both the symmetric and asymmetric modes of the beam system.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.376-377
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• 2010

In this paper, novel unidirectional auxiliary resonant commutated pole is proposed to improve the performance of zero-voltage soft-switching inverter. The proposed circuit keeps the advantages of the original soft-switching inverter, while providing more effective resetting capability in magnetizing current. Based on the advanced reset mechanism, auxiliary switches operate under a complete zero-current condition. The operating principle and steady-state analysis are presented theoretically, according to its operating modes. Accordingly, it proves the fact that the proposed unidirectional auxiliary resonant commutated pole breaks an unwanted magnetizing current loop effectively. The performance of the proposed circuit is verified by several simulation results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.4
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• pp.390-396
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• 2010

Resonant frequencies and the associated vibrational modes of multiwall carbon nanotubes are studied in this paper. The analysis is based on a multiple-elastic beam model, considering intertube radial displacements and the related internal degrees of freedom. Especially, van der Waals interaction is modified considering both all interaction between each layers in multi-wall carbon nanotubes and curvature effect. The results show that modified van der Waals interaction could significantly affect the natural frequencies of multi-walled carbon nanotubes. In particular, non-coaxial intertube resonance will be excited at the higher resonant frequencies of multiwall carbon nanotubes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.1
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• pp.48-52
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• 1986

An efficient numerical technique and computer program has been developed for the determination of the resonant frequencies and field coefficients of cylindrical dielectric disc resonators in a configuration which models the various effects present in real technical applications. it accounts for the influences due to shielding, plannar circuit substrate, dielectric support and a dielectric post used to tune out fabrication tolerances.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.224-227
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• 2000

Modal damping characteristics of the flexural vibration of a sandwich beam with paaially inserted viscoelastic layer have been quantitatively studied using the finite element analysis in combination with an experiment. Antisymmetric mode shapes of the flexural vibration were visualized by the holographic interferometry and agreed with those calculated by the finite element simulation. Effects of the length and thickness of partial viscoelastic layers on the system loss factor($\mu$) and resonant frequency($\omega$) were considerably latge at both symmetric and antisymmetric modes of the sandwich beam.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.71-75
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• 2017

A dual-band tunable-slot-type ground radiation antenna is proposed. The feeding structure consists of a coplanar waveguide and a lumped capacitor to excite currents for first- and second-order resonant modes of the ground. The resonant frequencies of both bands are controlled using a series combination of a capacitor and an inductor. The proposed design may be an attractive choice for mobile devices owing to its compact geometry and tunable operating frequencies. The measurement and simulation results of the proposed antenna show good agreement, indicating good impedance matching and radiation performance.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.980-983
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• 1996

This paper presents the method of determining state feedback gains of XPTOS for disk drive servomechanism based BESSEL filter prototype. A typical disk drive actuator can be modeled as second order dynamics for low frequencies. However, the response at higher frequencies shows resonant behavior which cannot be easily modeled. XPTOS consists of the nonlinear control region and the linear control region. In the linear control region, the poles of a second order nominal model of plant must be properly relocated by pole placement technique to attenuate resonant modes at high frequency and to attain minimum time state transition. It is difficult to select position to satisfy this object because velocity feedback gain is subjected to position feedback gain in XPTOS. Here poles of BESSEL filter prototype are selected to determine state feedback gains of XPTOS. Simulation results for disk drive servomechanism using XPTOS having state feedback gains by the proposed method are presented.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1720-1728
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• 2018

This paper proposes a novel soft starting algorithm by using PWM inverter technique to control an amplitude of the motor starting current at a single-phase induction motor (SPIM). Traditional SPIM starting methods such as a Split-Phase, Capacitor-Start, Permanent-Split Capacitor (PSC), Capacitor-Start Capacitor-Run (CSCR), basically cannot control the magnitude of starting current due to the fixed system structures. Therefore, in this paper, a soft starting algorithm based on a proportional resonant (PR) control with a variable and constant frequency is proposed to reduce the inrush current and starting up time. In addition, a transition algorithm for operation modes is devised to generate a constant voltage and constant frequency (CVCF). The validity and effectiveness of the proposed soft starting method and transition algorithm are verified through experimental results.

• Journal of Sensor Science and Technology
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• v.32 no.1
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• pp.62-65
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• 2023

The wave mode calculation of a large-scale optical system in comparison to the working wavelength is practically impossible because the computational cost increases exponentially. In this paper, we propose a method that can obtain the optical mode in a large-scale optical system. The method carries out simulations by dividing the calculation area into blocks and moving along the light axis along which the light propagates. By applying this method to the calculation of resonant modes in a ring-type optical resonator, which is mainly used for ring laser optical gyro sensors, the efficiency of the proposed method was verified.