• Transactions of the Society of Information Storage Systems
• /
• v.7 no.2
• /
• pp.80-84
• /
• 2011

In this paper, we propose the integrated design method that enables multi-physics modeling and coupled-field analysis by connecting an electromagnetic field and a structural field. We design the 3-axis moving magnet type actuator that has the high structural stiffness and the effective electromagnetic circuit generating large electromagnetic force. Through design of experiments (DOE) and optimization, the designed actuator is optimized and satisfies high dynamic characteristics over the desired specifications.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.20 no.1
• /
• pp.29-33
• /
• 1983

The loading condition, of a ship, especially a multi-purpose cargo carrier, in service, is often changed. Then, the prediction of natural frequency changes is necessary to provide measures for prevention of ship vibrations. In this paper a simplified method for the above purpose is presented. The bases of the method are analytical solutions for the lateral vibrations of uniform Timoshenko beams carrying a concentrated mass and the Dunkerley's formula. In this method a ship in the standard ballast condition is reduced to a uniform Timoshenko beam having same system parameters as those of the midship section. To investigate the validity of the proposed method, numerical calculations are carried out for a 46,000 DWT bulk carrier and compared with detailed calculations based on the finite difference method. Even in cases those the cargoes in a hold, length of which is about 13% of the ship's length, are reduced to a concentrated mass, the proposed method gives results of several percent differences from the detailed calculations up to the six-noded mode.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.52 no.4
• /
• pp.177-182
• /
• 2003

We have proposed the dimming controller using the AC chopper technique. The AC chopper changes the amplitude of the input source voltage with the same frequency. The conventional dimming controller is operated by controlling voltage phase with the triac. It has bad characteristics of the input current THD and the input power factor But the dimming controller using the ac chopper technique has a low current THD and a good power factor. The developed dimming controller is consist of the IGBT and the low pass filter. The system is operated by the variation circuit of the input source voltage and the microprocessor.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.4
• /
• pp.177-177
• /
• 2003

We have proposed the dimming controller using the AC chopper technique. The AC chopper changes the amplitude of the input source voltage with the same frequency. The conventional dimming controller is operated by controlling voltage phase with the triac. It has bad characteristics of the input current THD and the input power factor But the dimming controller using the ac chopper technique has a low current THD and a good power factor. The developed dimming controller is consist of the IGBT and the low pass filter. The system is operated by the variation circuit of the input source voltage and the microprocessor.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.52 no.1
• /
• pp.58-61
• /
• 2003

A loop power system has a nonlinear characteristics. Also it is very hard to analyse through a equation if a discontinuous characteristic of the ULTC is added to a system. However, the problem which is hard to analyse by equations can acquire the useful result with what use the genetic algorithm (GA) which is a multi-point search program. In this paper, we proved through a simulation that the proposed method can reduce an operation frequency of tap changers and improving the quality of voltage of the buses by decreasing the deviation between the actual voltage and the reference voltage through the coordinated control of the ULTC that use GA in the loop power system.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.3
• /
• pp.1250-1256
• /
• 2017

This paper proposes the design of microstrip patch antennas for dual-band polarization adjustment. The antenna has a multi-layer structure for dual-band operation, and each layer contains a resonating patch with surrounding strips separated into two parts. The antenna polarization is adjusted by varying the separated positions of the strips, while fixing other design parameters. To demonstrate the feasibility, an antenna sample with right-hand circular polarization is fabricated, and its antenna characteristics are measured in a full anechoic chamber. The operating principle of polarization adjustment in the dual frequency bands is also verified by observing near electromagnetic fields and the magnetic surface current density around the antenna.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.204-207
• /
• 2000

An ultrasonic linear motor was composed of a slider and a stator vibrator including piezoelectric material and elastic material. The ultrasonic linear motors mainly consist of an ultrasonic vibrator which generates elliptical oscillations. L$_1$-B$_4$ ultrasonic linear motor use longitudinal and bending multi-vibration. In order to low driving voltage and improve the life time of the ultrasonic oscillator, we used stacked piezoceramics. Stacked piezoceramics are adhered to aluminum elastic material. The finite element method was used to optimize dimension of ultrasonic vibrator and direction of vibratory displacement. As a result of estimating the characteristics of the ultrasonic linear motor, no-load velocity was 2.04[m/s] when applied voltage was 70[V$\sub$rms/] in resonance frequency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.1
• /
• pp.56-60
• /
• 2002

A low-temperature cofired-ceramic (LTCC) multi-layer ceramic (MLC) band-pass filter (BPF) is presented, which has the benefits of low cost and small size. The BPF is designed for an IMT-2000 handset. The computer-aided design technology is also presented. The BPF with an attenuation pole at below the passband has been discussed and realized. The equivalent circuit of the BPF was established by transmission lines and lumped capacitors. The frequency characteristics of the LTCC-MLC BPF is well acceptable for IMT-2000 application.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2006.03a
• /
• pp.519-526
• /
• 2006

This paper compares the seismic response control performance of linear and non-linear models fer tuned liquid damper (TLD). The existing linear and nonlinear TLD models were used for the numerical analysis of single degree of freedom (SDOF) and multi degree of freedom (MDOF) systems with TLD. The nonlinear model considers the variation of the frequency and damping of the TLD with varying excitation amplitude while the linear one has the invariant parameters. Numerical analysis results from SDOF systems indicate that the nonlinear model shows about 5% better control performance than linear one when the mass ratio is 2% and the optimal parameters for reducing peak responses are dependent on the characteristics of the excitation earthquake loads.

• Smart Structures and Systems
• /
• v.23 no.6
• /
• pp.553-564
• /
• 2019

Modeling of magnetorheological (MR) dampers for cable vibration control to facilitate the design of even more effective and economical systems is still a challenging task. In this study, a parameter-adaptive three-element model is first established for a full-scale MR damper based on laboratory tests. The parameters of the model are represented by a set of empirical formulae in terms of displacement amplitude, voltage input, and excitation frequency. The model is then incorporated into the governing equation of cable-damper system for investigation of open-loop vibration control of stay cables in a cable-stayed bridge. The concept of optimal voltage/current input achieving the maximum damping for the system is put forward and verified. Multi-mode suboptimal and Single-mode optimal open-loop control method is then developed. Important conclusions are drawn on application issues and unique characteristics of open-loop cable vibration control using MR dampers.