• Journal of information and communication convergence engineering
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• v.1 no.1
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• pp.44-47
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• 2003

The split ground structure for microstrip structure can be used to protect analog/RF signal from SSN interference of digital circuits on PCB with common ground. However, the split ground structure gives rise to undesired emissions that may interfere with nearby circuitry due to the ground discontinuity. In this paper, we have proposed the modified structure, Dumbbell shaped SGS and the method to reduce the radiation by adding the lumped resistor on the proposed Dumbbell shaped SGS.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.169-176
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• 1997

In this study, vertical ground motion effects on rocking response of free standing structure are investigated. Based on the mathematical model, computer program is developed using Kutta's Fourth-Order Method. Using the program, several parametric studis are performed to predict the effects of vertical ground motion. From the results of this study, it can be found that the vertical ground motion may overturn the structure which is stable under the horizontal ground motion, stabilize the structure which overturns due to horizontal ground motion alone, and delay the time of overturning of the structure or greatly reduce the rocking of the structure. It is concluded that the effect of vertical ground motion on the rocking response of free standing structure is apparently not systematic.

• Earthquakes and Structures
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• v.23 no.2
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• pp.169-181
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• 2022

To research the dynamic response of the high-rise structure under the rocking ground motion, which we believed that the effect cannot be ignored, especially accompanied by vertical ground motion. Theoretical analysis and shaking table seismic simulation tests were used to study the response of a high-rise structure to excitation of a H-V-R ground motion that included horizontal, vertical, and rocking components. The use of a wavelet analysis filtering technique to extract the rocking component from data for the primary horizontal component in the first part, based on the principle of horizontal pendulum seismogram and the use of a wavelet analysis filtering technique. The dynamic equation of motion for a high-rise structure under H-V-R ground motion was developed in the second part, with extra P-△ effect due to ground rocking displacement was included in the external load excitation terms of the equation of motion, and the influence of the vertical component on the high-rise structure P-△ effect was also included. Shaking table tests were performed for H-V-R ground motion using a scale model of a high-rise TV tower structure in the third part, while the results of the shaking table tests and theoretical calculation were compared in the last part, and the following conclusions were made. The results of the shaking table test were consistent with the theoretical calculation results, which verified the accuracy of the theoretical analysis. The rocking component of ground motion significantly increased the displacement of the structure and caused an asymmetric displacement of the structure. Thus, the seismic design of an engineering structure should consider the additional P-△ effect due to the rocking component. Moreover, introducing the vertical component caused the geometric stiffness of the structure to change with time, and the influence of the rocking component on the structure was amplified due to this effect.

• Earthquakes and Structures
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• v.26 no.1
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• pp.17-30
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• 2024

Earthquakes can lead to substantial damage to buildings, with long-period ground motion being particularly destructive. The design of high-performance building structures has become a prominent focus of research. The double-story isolated structure is a novel type of isolated structure developed from base isolated structure. To delve deeper into the building performance of double-story isolated structures, the double-story isolated structure was constructed with the upper isolated layer located in different layers, alongside a base isolated structure for comparative analysis. Nonlinear elastoplastic analyses were conducted on these structures using different ground motion inputs, including ordinary ground motion, near-field impulsive ground motion, and far-field harmonic ground motion. The results demonstrate that the double-story isolated structure can extend the structural period further than the base isolated structure under three types of ground motions. The double-story isolated structure exhibits lower base shear, inter-story displacement, base isolated layer displacement, story shear, and maximum acceleration of the top layer, compared to the base isolated structure. In addition, the double-story isolated structure generates fewer plastic hinges in the frame, causes less damage to the core tube, and experiences smaller overturning moments, demonstrating excellent resistance to overturning and a shock-absorbing effect. As the upper isolated layer is positioned higher, the compressive stress on the isolated bearings of the upper isolated layer in the double-story isolated structure gradually decreases. Moreover, the compressive stress on the isolated bearings of the base isolated layer is lower compared to that of the base isolated structure. However, the shock-absorbing capacity of the double-story isolated structure is significantly increased when the upper isolated layer is located in the middle and lower section. Notably, in regions exposed to long-period ground motion, a double-story isolated structure can experience greater seismic response and reduced shock-absorbing capacity, which may be detrimental to the structure.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.70-73
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• 2008

Because the inclination and crack of stone pagoda structure are caused by the depth difference of soft soil ground and ground subsidence in weak zone, a long-term conservation of stone pagoda structure is difficult. But it is insufficient to analyze the behavior of stone pagoda structure considering soft soil ground in our country. Therefore, we find the structural effect happening in stone pagoda structure by analyzing mechanically a specific of soft soil ground and carry out structural analysis and structural modelling of stone pagoda structure that considers soft soil ground by discrete element method.

• Journal of information and communication convergence engineering
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• v.9 no.2
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• pp.150-154
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• 2011

In this paper a four-pole elliptic function bandpass filter is designed with two ground slots. A research of microstrip bandpass filters (BPF) using defected ground structures (DGS) is presented. DGS technique allows designs of tight couplings without the necessity of using very narrow coupling gaps. The simulator Sonnet is used to design the resonator and to calculate the coupling coefficient of the basic coupling structure. Compared to similar microstrip filters without defected ground structure, the simulated performances of these novel structures indicate some technological advantages.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.6
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• pp.279-289
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• 2014

Considering a rigorously fluid-structure interaction, a method for an earthquake response analysis of a floating offshore structure subjected to vertical ground motion from a seaquake is developed. Mass, damping, stiffness, and hydrostatic stiffness matrices of the floating offshore structure are obtained from a finite-element model. The sea water is assumed to be a compressible, nonviscous, ideal fluid. Hydrodynamic pressure, which is applied to the structure, from the sea water is assessed using its finite elements and transmitting boundary. Considering the fluid-structure interaction, added mass and force from the hydrodynamic pressure is obtained, which will be combined with the numerical model for the structure. Hydrodynamic pressure in a free field subjected to vertical ground motion and due to harmonic vibration of a floating massless rigid circular plate are calculated and compared with analytical solutions for verification. Using the developed method, the earthquake responses of a floating offshore structure subjected to a vertical ground motion from the seaquake is obtained. It is concluded that the earthquake responses of a floating offshore structure to vertical ground motion is severely influenced by the compressibility of sea water.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.233-238
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• 2003

With the growth of high speed circuit, unwanted system noise is increased and multipoint ground is used to reduce this noise. PCB screw ground structure has radiation noise by ground loop between screws. In order to solve this problem, in this paper, we proposed improved PCB ground structure. Proposed structure improves noise absorption by using microwave absorber and conductive copper tape. We measured radiation PCB noise in the range of 1 ㎓ to 3 ㎓ to investigate proposed structure usefulness. From these results, under 2 ㎓ range proposed structure has noise reduction by 2.62 dBuV/m, which compared with screw ground.

• Earthquakes and Structures
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• v.27 no.1
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• pp.41-55
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• 2024

There are obvious differences between the characteristics of offshore ground motion and onshore ground motion in current studies, and factors such as water layer and site conditions have great influence on the characteristics of offshore ground motion. In addition, unlike seismic response analysis of offshore superstructures such as sea-crossing bridges, tunnels are affected by offshore soil constraints, so it is necessary to consider the dynamic interaction between structure and offshore soil layer. Therefore, a seismic response analysis model considering the seawater, soil layer and tunnel structure coupling is established. Firstly, the measured offshore and different soil layers onshore ground records are input respectively, and the difference of seismic response under different types of ground motions is analyzed. Then, the models of different site conditions were input into the measured onshore bedrock strong ground motion records to study the influence of seawater layer and silt soft soil layer on the seabed and tunnel structure. The results show that the overall seismic response between the seabed and the tunnel structure is more significant when the offshore ground motion is input. The seawater layer can suppression the vertical seismic response of seabed and tunnel structure, while the slit soft soil layer can amplify the horizontal seismic response. The results will help to promote seismic wave selection of marine structures and provide reference for improving the accuracy of seismic design of immersed tunnels.

• Tunnel and Underground Space
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• v.20 no.4
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• pp.292-298
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• 2010

The purpose of this study is to evaluate an effect of ground vibration caused by blasting on the concrete brick structure. For the purpose, dynamic response time-history of the structure assumed single degree of freedom (SDOF) system and vibration time-history directly measured from the structure were examined, using Newmark $\beta$ method based on data measured at ground. The time-history was interpreted from the measured data of ground and structure in single hole blasting. Vibration magnitude between ground vibration and structure in single hole blasting and 20 ms interval blasting was about three times and was shown larger vibration on the structure. By time-history analysis of structure dynamic response, the value was almost the same one with the data measured from the structure. It indicates that the vibration characteristics of structures may be predicted on the basis of the ground vibration data measured from the sub-ground of structure.