• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.196-203
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• 2006

An air-gap type FBAR was designed using Leach equivalent model for analyzing a vertical structure of the FBAR. For the top electrode, Pt, and the bottom electrode, Au, of $1.2{\mu}m$ thickness and the piezoelectric of 0.8,urn thickness, the resonance and anti-resonance occurred at 2.401 GHz and 2.460 GHz, respectively. $S_{11}$ was increased and $S_{21}$ was decreased as the resonance area of FBAR was widened. We observed the characteristics of insertion loss, bandwidth and out-of-band rejection of ladder-type FBAR BPF by changing resonance areas of series and shunt resonators and by adding stages. As the resonance area of series resonator was increased, insertion loss was improved but out-of-band rejection was degraded. And as the resonance area of shunt resonator was increased, insertion loss was degraded a little but out-of-band rejection was improved even without adding stages. We, also, changed the shape of the resonance area from square shape to rectangle shape to examine the effects of the resonator shape on the characteristics of the BPF. The best performances were observed when the sizes of series and shunt resonator are $150{\mu}m{\times}l50{\mu}m\;and\;5{\mu}m{\times}50{\mu}m$, respectively. Out-of-band rejection was improved about 10dB and bandwidth was broadened from 30MHz to 100MHz utilizing inductor tuning on $2{\times}2\;and\; 4{\times}2$ ladder-type BPFs.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.213-217
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• 2008

The flux-lock type superconducting fault current limiter(SFCL) can apply the magnetic field into the high-$T_C$ superconducting(HTSC) element by adopting the magnetic field coil in its third winding. To apply the magnetic field into the HTSC element effectively, the capacitor for LC resonance is connected in series with the magnetic field coil. However, the current waveform of third winding for the application of the magnetic field is affected by the LC resonance condition for the frequency of the source voltage and can affect the waveform of the limited fault current. In this paper, the current waveform of the third winding in the flux-lock type SFCL according to LC resonance condition during a fault period was analyzed. From the differential equation for its electrical circuit, the current equation of the third winding was derived and described with the natural frequency and the damping ratio as design parameters. Through the analysis according to the design parameters of the third winding, the waveform of the limited fault current was confirmed to be influenced by the current waveform of the third winding and the design condition for the stable fault current limiting operation of this SFCL was obtained.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.3
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• pp.252-261
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• 2016

A spar-type floating substructure that is being widely used for offshore wind power generation is vulnerable to resonance in the heave direction because of its small water plane area. For this reason, the stable dynamic response of this floating structure should be ensured by accurately identifying the resonance characteristics. The purpose of this study is to analyze the characteristics of the combination resonance between the excitation frequency of a regular wave and natural frequencies of the floating substructure. First, the nonlinear equations of motion with two degrees of freedom are derived by assuming that the floating substructure is a rigid body, where the heaving motion and pitching motions are coupled. Moreover, to identify the characteristics of the combination resonance, the nonlinear term in the nonlinear equations is approximated up to the second order using the Taylor series expansion. Furthermore, the validity of the approximate model is confirmed through a comparison with the results of a numerical analysis which is made by applying the commercial software ANSYS AQWA to the full model. The result indicates that the combination resonance occurs at the frequencies of ${\omega}{\pm}{\omega}_5$ and $2{\omega}_{n5}$ between the excitation frequency (${\omega}$) of a regular wave and the natural frequency of the pitching motion (${\omega}_{n5}$) of the floating substructure.

• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.513-521
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• 2018

In this paper, the resonance response of spar-type floating platform in coupled heave and pitch motion is investigated using a CPU time-effective numerical method. A coupled nonlinear 2-DOF equation of motion is derived based on the potential wave theory and the rigid-body hydrodynamics. The transient responses are solved by the fourth-order Runge-Kutta (RK4) method and transformed to the frequency responses by the digital Fourier transform (DFT), and the first-order approximation of heave response is analytically derived. Through the numerical experiments, the theoretical derivation and the numerical formulation are verified from the comparison with the commercial software AQWA. And, the frequencies of resonance arising from the nonlinear coupling between heave and pitch motions are investigated and justified from the comparison with the analytically derived first-order approximation of heave response.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.638-641
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• 2002

This paper presents design and construct of flat type step-down piezoelectric transformer for the application to AC-adapters. This piezoelectric transformer operated in resonance vibration mode. In this paper, Finite element method(FEM) was used for analysis piezoelectric transformers. Vibration mode and electric field of piezoelectric transformer at resonance frequency were simulated. Using this simulation, we manufactured flat type piezoelecric transformer and measured its output characteristics. As results, output power was linearly increased by increasing input power at resonance frequency. And it was found that the transformer exhibited an output power of 11.4[W] at 60[V] input voltage. From these results, we expect that this piezoelecric transformer can be applied to AC adapters.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.698-699
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• 2005

Levels of fumonisins, mycotoxins produced by fungal species, must be accurately and rapidly monitored to ensure food safety. In this study, using surface plasmon resonance sensor, a batch-type biosensor was fabricated to detect fumonisin $B_1$. By applying this biosensor to fumonisin $B_1$ solutions of 0 to 6 ppm, a significant calibration model was developed for measurement. Coefficient of determination in regression analysis for the model was 0.920. Results indicate that detection of fumonisin $B_1$ by surface plasmon resonance biosensor was highly feasible.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.4
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• pp.206-210
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• 2012

In this paper wireless power transmission is discussed. The concept of non-radiative magnetic coupled resonance type wireless power transmission was introduced by MIT team at 2007, non-radiative type has been focused by many researchers. Authors present design of circuit parameters including driving frequency and verify the design by computer simulation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.688-692
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• 2003

For high voltage operation, a new type of piezoelectric transformer using radial vibration of disk, poled with the same direction was proposed. The piezoelectric ceramics was composed to PZT-PMN-PSN. The diameter and thickness of a disk type piezoelectric transformer were 45［mm］and 4［mm］, respectively The surface ratio of driving electrode and generating electrode of the piezoelectric transformer was 2 : 1. The resonance characteristics of input admittance, step-up voltage ratio and power transmission efficiency of the piezoelectric transformer were measured by varying the load resistance(0.1∼70［kΩ］). As a result, both resonance frequency and step-up voltage ratio increased with increasing load resistance. The step-up voltage ratio was reached more than 60 times under no load resistance. The maximum efficiency of 97% at load resistance of 2kΩ was obtained.

• The Journal of Advanced Prosthodontics
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• v.3 no.1
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• pp.10-15
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• 2011

PURPOSE. This study investigated the influence of bone quality and surgical technique on the implant stability quotient (ISQ) value. In addition, the influence of interfacial bone quality, directly surrounding the implant fixture, on the resonance frequency of the structure was also evaluated by the finite element analysis. MATERIALS AND METHODS. Two different types of bone (type 1 and type 2) were extracted and trimmed from pig rib bone. In each type of bone, the same implants were installed in three different ways: (1) Compaction, (2) Self-tapping, and (3) Tapping. The ISQ value was measured and analyzed to evaluate the influence of bone quality and surgical technique on the implant primary stability. For finite element analysis, a three dimensional implant fixture-bone structure was designed and the fundamental resonance frequency of the structure was measured with three different density of interfacial bone surrounding the implant fixture. RESULTS. In each group, the ISQ values were higher in type 1 bone than those in type 2 bone. Among three different insertion methods, the Tapping group showed the lowest ISQ value in both type 1 and type 2 bones. In both bone types, the Compaction groups showed slightly higher mean ISQ values than the Self-tapping groups, but the differences were not statistically significant. Increased interfacial bone density raised the resonance frequency value in the finite element analysis. CONCLUSION. Both bone quality and surgical technique have influence on the implant primary stability, and resonance frequency has a positive relation with the density of implant fixture-surrounding bone.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8335-8338
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• 2016

Purpose: To make a comparison of single voxel magnetic resonance spectroscopy (SV-MRS) and dynamic contrast enhancement (DCE) MRI for differentiation of benign and malignant breast lesions in a sample of Iranian women. Materials and Methods: A total of 30 women with abnormal breast lesions detected in mammography, ultrasound, or clinical breast exam were examined with DCE and SV-MRS. tCho (total choline) resonance in MRS spectra was qualitatively evaluated and detection of a visible tCho peak at 3.2 ppm was defined as a positive finding for malignancy. Different types of DCE curves were persistent (type 1), plateau (type 2), and washout (type 3). At first, lesions were classified according to choline findings and types of DCE curve, finally being compared to pathological results as the standard reference. Results: this study included 19 patients with malignant lesions and 11 patients with benign ones. While 63.6 % of benign lesions (7 of 11) showed type 1 DCE curves and 36.4% (4 of 11) showed type 2, 57.9% (11of 19) of malignant lesions were type 3 and 42.1% (8 of 19) type 2. Choline peaks were detected in 18 of 19 malignant lesions and in 3 of 11 benign counterparts. 1 malignant and 8 benign cases did not show any visible resonance at 3.2 ppm so SV-MRS featured 94.7% sensitivity, 72.7 % specificity and 86.7% accuracy.Conclusions: The present findings indicate that a combined approach using MRS and DCE MRI can improve the specificity of MRI for differentiation of benign and malignant breast lesions.