• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.340-343
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• 2019

In this paper, a problem of mechanical resonance between traction motor's rigid body mode and traction motor's excitation force is introduced, and a bogie design variable affecting the control of resonance response is reviewed numerically. To solve the resonance problem in rotating machinery with variable rotational speeds, resonance frequency should be out of rotational machine's operation range or dynamic stiffness of structures should be increased for resonance response enough to be low. In general, operation range of a traction motor is from 0 r/min to 4800 r/min. It is not possible that all bogie modes are more than 80 Hz. Therefore, it is very important to find design factor affecting resonance response of traction motor's rigid body modes. It is found that key design variable is the gab between transom pipes from finite element analysis. The larger gab is, the higher resonance response when resonance between traction motor's excitation force and traction motor's rigid body mode is happened.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.2
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• pp.355-360
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• 2024

In this paper, in implementing a 4-coil resonant wireless power transmission system, we studied the discharge phenomenon that occurs at the end of the transmitting resonance coil. Resonant wireless power transmission consists of a power supply coil, a transmitting resonance coil, a power receiving resonance coil, and a load coil. The transmitting resonance coil serves to amplify the magnetic field generated from the power supply coil and transmits it to the front receiving resonance coil. When a high current flows through the power supply coil in order to transmit large power, a high voltage is induced at the end of the transmitting resonance coil. It causes line-to-line discharge. Line-to-line discharge phenomenon damages the transmitter case and renders the transmitter unusable. Therefore, in order to eliminate this line-to-line discharge phenomenon, the voltage induced in the transmitting resonance coil that causes line-to-line discharge was analyzed and a solution was proposed.

• Proceedings of the KSLP Conference
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• 2017.04a
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• pp.109-109
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• 2017

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.08a
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• pp.91-91
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• 2002

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.148-153
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• 1998

A resonance is the one of major reasons of vibration problems occurred in industrial fields. To reduce vibration level due to resonance, structure reinforcements or change of the dynamic characteristics is generally applied. In this paper, the troublesome vibration levels of the motor shaft and auxiliary condensate pump are reduced by avoiding resonance.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.216-219
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• 2005

In this study, we will explain the design, test results and analysis of system for measuring the small mass in the microgravity environment. It is so difficult to measure the mass by sensing the gravity as the ground in the microgravity environment. The suggested method is to measure the resonance frequency of a sample. The resonance frequency may be measured as a function of mass. If we know the resonance frequency of the mass, we can guess the mass by detecting the resonance frequency. Piezoelectric ceramics have the characteristics that resonance frequency is changed by total mass which are its mass and the attached mass. This system have some problems but we verified that we can measure the unknown mass using the resonance frequency as the mass.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.7 s.349
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• pp.29-37
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• 2006

This paper presents a new analytical model to suppress RLC resonance effects which inevitably occur in power/ground lines due to on-chip decoupling capacitor and other interconnect circuit parasitics (i.e., package inductance, on-chip decoupling capacitor, and output drivers, etc.). To characterize the resonance effects, the resonance frequency of the circuit is accurately estimated in an analytical manner. Thereby, a decoupling capacitor size to suppress the resonance for a suitable circuit operation is accurately determined by using the estimated resonance frequency. The developed novel design methodology is verified by using $0.18{\mu}m$ process-based-HSPICE simulation.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2338-2349
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• 2016

This paper presents an impedance-matching-based control scheme for the harmonic resonance damping of multiple grid-connected-converters (GCCs) with LCL filters. As indicated in this paper, harmonic resonance occurs if a GCC possesses an output impedance that is not matched with the rest of the network in some specific frequency bands. It is also revealed that the resonance frequency is associated with the number of GCCs, the grid impedance and even the capacitive loads. By controlling the grid-side current instead of the converter-side current, the critical LCL filter is restricted as an internal component. Thus, the closed-loop output impedance of the GCC within the filter can be configured. The proposed scheme actively regulates the output impedance of the GCC to match the impedance of the external network, based on the detected resonance frequency. As a result, the resonance risk of multiple GCCs can be avoided, which is beneficial for the plug-and-play property of the GCCs in microgrids. Simulation and experimental results validate the effectiveness of the proposed method.

• Investigative Magnetic Resonance Imaging
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• v.21 no.4
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• pp.273-275
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• 2017

Thiemann's disease is a form of idiopathic avascular necrosis of the immature epiphyses of the phalanges of the fingers and toes. Few cases of Thiemann's disease have been reported because the disease is rare and difficult to diagnose. To the best of our knowledge, magnetic resonance imaging (MRI) findings of Thiemann's disease have not been reported. Here, we report a case of Thiemann's disease diagnosed by typical clinical symptoms and characteristic MRI findings before radiologic bony abnormalities were apparent.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.172-175
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• 2013

We compare the relative usefulness of common basis functions and numerical integration methods in representing complex resonance state encountered in the molecular scattering problem of aluminum dimer electronic predissociation. Specifically, the basis set size and computing CPU times are monitored in order to find the minimum requirement for ensuring the modest accuracy of calculated resonance energies (0.1 $cm^{-1}$) for more than 100 resonance states. The combination of the so-called one-dimensional box eigenfunctions and energy-dependent boundary functions are found to be most efficient if integration is done using the basis set quadrature rules.