• 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 Korean Geotechical Society Conference
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• 2005.10a
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• pp.564-569
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• 2005

Usually, Steel pipe grouting method or cut and cover method has been applied to tunnel with very shallow overburden or it is situated in valley. However, in case of lack of overburden height to reinforcement tunnel crown which is very difficult to construction. Also, application of cut and cover method that do not consider surrounding site condition causes popular enmity generation and environmental damage. It is the best alternative method that reduces the amount of excavated soil and excavate tunnel under ground to solve these problems. The tunneling method using cover structure which is to prevent a tunnel from collapse because this method can be reduce excavation area and construct tunnel under ground after set a cover structure and backfill ground. In this study, to know more effective structure type, comparative analysis was performed to behavior characters of slab and arch type construction that can be used to cover structure. Also a 2D and 3D numerical analysis have been performed to verify the stability of ground during excavation. As the result, the tunneling method using cover structure that it can be good alternative method for tunnel with shallow overburden and it through valley

• 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 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.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1159-1164
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• 2005

Seismic analysis methods in use on ground structure are equivalentstatic analysis, response-displacement method and dynamic analysis etc. Equivalentstatic analysis does not considerdynamic effect, and dynamic analysis process is very complex. then 'Urbanrail transit earthquake-resistance design standard (2005.06)' is persuading that analyze by response displacement method that consider enough dynamic effect of ground structure statically. But, It is very complex and difficult to apply response-displacement method in the field. So, modified equivalentstatic analysis or pseudo static analysis that is easy to apply in the field and have rationality of design is practically used. In this study, I try to prescribe the applicable scale of structure and static analysis that have calculative effectiveness about response-displacement method by comparing and analyzing the result of each analysis method according to the scale of urban rail transit' box type concrete structure and by performing seismic analysis that apply modified equivalentstatic analysis, pseudo static analysis and response-displacement method changing the kind of ground, depth of bedrock, size of structure.

• 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.

• 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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1187-1193
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• 2006

Traditionally, the continuum-based topology optimization methods employing the SIMP technique have been used to design compliant mechanisms. Although they have been successful, the optimized mechanisms by the methods are usually difficult to manufacture because of their geometrical complexities. The objective of this study is to develop a topology optimization method that can produce easy-to-fabricate mechanism structure. The proposed method is a ground beam method where beam connectivity is controlled by the beam joint stiffness. In this approach, beam joint stiffness determines the mechanism configuration. Because b the ground structure beams have uniform thicknesses varying only discretely, the resulting mechanism topologies become easily manufacturable.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.659-671
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• 2008

A procedure to analyse the space frame structure fixed at base as well as resting on sliding bearing using total or absolute displacement in dynamic equation is developed. In the present method, the effect of ground acceleration is not considered as equivalent force. Instead, the ground acceleration is considered as a known value in the acceleration vector at degree of freedom corresponding to base of the structure when the structure is in non-sliding phase. When the structure is in sliding phase, only a force equal to the maximum frictional resistance is applied at base. Also, in this method, the stiffness matrix, mass matrix and the damping matrix will not change when the structure enters from one phase to another. The results obtained from the present method using absolute displacement approach are compared with the results obtained from the analysis of structure using relative displacement approach. The applicability of the analysis is also demonstrated to obtain the response of the structure resting on sliding bearing with restoring force device.

• Earthquakes and Structures
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• v.16 no.2
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• pp.165-175
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• 2019

Incremental dynamic analysis (IDA), as an accurate method to evaluate the parameters of structural performance levels, requires many non-linear time history analyses, using a set of ground motion records which are scaled to different intensity levels. Therefore, this method is very computationally demanding. In this study, a new method is presented to estimate the summarized (16%, 50%, and 84% fractiles) IDA curves of a first-mode dominated structure using discrete wavelet transform and bees optimization algorithm. This method reduces the number of required ground motion records for the prediction of the summarized IDA curves. At first, a subset of first list ground motion records is decomposed by means of discrete wavelet transform which have a low dispersion estimating the summarized IDA curves of equivalent SDOF system of the main structure. Then, the bees algorithm optimizes a series of factors for each level of detail coefficients in discrete wavelet transform. The applied factors change the frequency content of original ground motion records which the generated ground motions records can be utilized to reliably estimate the summarized IDA curves of the main structure. At the end, to evaluate the efficiency of the proposed method, the seismic behavior of a typical 3-story special steel moment frame, subjected to a set of twenty ground motion records is compared with this method.