• Earthquakes and Structures
• /
• v.7 no.1
• /
• pp.83-99
• /
• 2014

This study is devoted to estimate higher-mode effects for multi-story structures with considering soil-structure interaction subjected to decomposed parts of near-fault ground motions. The soil beneath the super-structure is simulated based on the Cone model concept. Two-dimensional structural models of 5, 15, and 25-story shear buildings are idealized by using nonlinear stick models. The ratio of base shears for the soil-MDOF structure system to those obtained from the equivalent soil-SDOF structure system is selected as an estimator to quantify the higher-mode effects. The results demonstrate that the trend of higher-mode effects is regular for pulse component and has a descending variation with respect to the pulse period, whereas an erratic pattern is obtained for high-frequency component. Moreover, the effect of pulse component on higher modes is more significant than high-frequency part for very short-period pulses and as the pulse period increases this phenomenon becomes vice-versa. SSI mechanism increases the higher-mode effects for both pulse and high-frequency components and slenderizing the super-structure amplifies such effects. Furthermore, for low story ductility ranges, increasing nonlinearity level leads to intensify the higher-mode effects; however, for high story ductility, such effects mitigates.

• Journal of the Korean Society for Precision Engineering
• /
• v.8 no.2
• /
• pp.36-46
• /
• 1991

This study was carried out to investigate the characteristic of dynamic component in drilling. Materials used were carbon steel, brass and cast iron, and the drills used were high speed steel drill and cemented carbide. The cutting resistance generated in drilling was detected with the aid of piez0-electric tool dynamometer which has an excellent frequency response, and then the magnitude and shape of dynamic component and its frequency component as well were analyuzed. After a thorough study of interrelationship, the obtained results are as follows; 1) The shape of torque and thrust of the early drilling are different. 2) The shapes of dynamic component can be classified into four kinds. 3) Torque is related to frequency more closely than thrust. 4) As cutting speed increased, dynamic component increased. 5) Chipping took place continuously, and its size decreased as cutting proceeded.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.2
• /
• pp.122-129
• /
• 2009

Frequency is an important operating parameter of a power system. It is essential that the frequency of a power system be maintained very close to its nominal frequency. And frequency measurement devices have need to measure a fast and accurate of frequency using voltage signals. This paper proposes a comparative study of frequency estimation techniques using the high speed FIR filter based algorithm, the DFT filter based algorithm using phasor angle between two phasors, and positive sequence component based algorithm using the half angle between two successive positions of phasor. The discussed three techniques have been formed through numerical manipulation of a discrete system. The proposed techniques have been tested using signals obtained from selected power system model using ATP simulation package. Some test results are shown in this paper.

• Journal of the Korean Society for Railway
• /
• v.9 no.1 s.32
• /
• pp.18-22
• /
• 2006

The dynamic characteristics of the current collection system are investigated by conducting a test run in which signals from accelerometers and load cells attached to the various parts of the pantograph are analyzed in both the time and frequency domains. The dynamic characteristics of the current collection system are found to be strongly influenced by the train speed; the fluctuation in the pantograph motion increases in direct proportion to the train speed. There exist two major fequency components in the pantograph motion related to the current collection, a speed-dependent component arising from the train traversing a span of the catenary, and a speed-independent component related to the pantograph resonant frequency. The train acceleration is also found to exert strong influence on the current collection system characteristics. The effect of the train motion is found to be stronger on the speed-dependent frequency component than on the speed-independent one.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.2
• /
• pp.262-270
• /
• 2013

A boundary protection method for power distribution line based on equivalent boundary effect is presented in this paper. In the proposed scheme, the equivalent resonance component with a certain central frequency is sleeve-mounted at the beginning of protected zone. The 'Line Boundary' is built by using boundary effect, which is created by introducing impedance in the primary-side of line. The 'Line Boundary' is significantly different from line wave impedance. Therefore, the boundary protection principle can be applied to power distribution line without line traps. To analyze the frequency characteristic corresponding to traveling-waves of introducing impedance in the primary-side of line, distributed parameters model of equivalent resonance component is established. The results of PSCAD/EMTDC simulation prove the obvious difference of voltage high frequency component between internal faults and external faults due to equivalent resonance component, and validate the scheme.

• ETRI Journal
• /
• v.45 no.1
• /
• pp.131-137
• /
• 2023

The phase reconstruction process in digital holographic microscopy involves a trade-off between the phase error and the high-spatial-frequency components. In this reconstruction process, if the narrow region of the sideband is windowed in the Fourier domain, the phase error from the DC component will be reduced, but the high-spatial-frequency components will be lost. However, if the wide region is windowed, the 3D profile will include the high-spatial-frequency components, but the phase error will increase. To solve this trade-off, we propose the high-variance pixel averaging method, which uses the variance map of the reconstructed depth profiles of the windowed sidebands of different sizes in the Fourier domain to classify the phase error and the high-spatial-frequency components. Our proposed method calculates the average of the high-variance pixels because they include the noise from the DC component. In addition, for the nonaveraged pixels, the reconstructed phase data created by the spatial frequency components of the widest window are used to include the high-spatialfrequency components. We explain the mathematical algorithm of our proposed method and compare it with conventional methods to verify its advantages.

• Proceedings of the IEEK Conference
• /
• 2000.06a
• /
• pp.205-208
• /
• 2000

In this paper, we design Tracking Filter that is principal component of Frequency Hopping System. This filter can acquire hopping pattern in short time and track it at high speed. This is high Q, narrowband, RF filter whose center frequency is controlled digitally between 30MHz ∼ 88MHz.

• Journal of Broadcast Engineering
• /
• v.17 no.3
• /
• pp.459-470
• /
• 2012

In this paper, we propose a method to upsample a low-resolution depth map to a high-resolution version. While conventional camera sensors produce high-resolution color images, the sizes of the depth maps of range/depth sensors are usually low. In this paper, we consider the utilization of high-frequency components to the conventional depth map interpolation methods such as bilinear, bicubic, and bilateral. The proposed method is composed of the three steps: high-frequency component extraction, high-frequency component application, and interpolation. Two objective evaluation measures such as sharpness degree and blur metric are used to examine the performance. Experimental results show that the proposed method significantly outperforms other conventional methods by a factor of 2 in terms of sharpness degree. As well, a blur metric is reduced by a factor of 14 %.

• Journal of Sensor Science and Technology
• /
• v.27 no.2
• /
• pp.112-117
• /
• 2018

In this study, a bender-type piezoelectric energy harvester was fabricated and evaluated to compensate for the disadvantages of high-power generation only in the resonance frequency range of a piezoelectric harvester using a piezoelectric cantilever. The generated power was investigated according to various changes in the vibration environment. Compared with the piezoelectric cantilever module, the bender-type piezoelectric module showed a larger number of peak voltages. The primary peak voltage shifted toward the low frequency when the spring was coupled to the bender-type piezoelectric module. The harvester of the three bender-type modules had a vibration frequency exceeding 1 mW in the 34-45 Hz range and generated 3.112 mW of power at the vibration frequency of 38 Hz. The harvester of the six bender-type modules had a vibration frequency exceeding 1 mW in the 31-45 Hz range and generated 3.081 mW of power at the vibration frequency of 35 Hz.

• Nuclear Engineering and Technology
• /
• v.55 no.7
• /
• pp.2407-2418
• /
• 2023

Internal replaceable electronic module substitutions can impact EMC (ElectroMagnetic Compatibility) qualification testing and results if EMC testing is conducted at the cabinet level. The impact of component substitutions on EMC qualification results therefore should be evaluated. If a qualitative evaluation is not adequate to ensure that the modified product will not impact the cabinet level EMC qualification results, a new qualification testing should be conducted. Component level retesting should be conducted under electromagnetically equivalent conditions with the cabinet level test. This paper analyzes the propagation of conducted susceptibility test waveforms in a representative cabinet and evaluates the impact of component substitutions on cabinet level EMC qualification results according to the location of the replacement items. A guideline for a qualitative evaluation of the impact of component substitutions is described based on the propagation of the conducted susceptibility test waveforms. A module level test method is also described based on an analysis of the shielding effectiveness of the cabinet.