• Journal of the Korean Society of Safety
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• v.19 no.4 s.68
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• pp.109-116
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• 2004

The dynamic behavior of the rectangular liquid storage structure is known to be greatly influenced by fluid-structure interaction. By mounting the liquid storage structure on the properly designed base isolators, dynamic response of the superstructure can be reduced. However, base isolators inevitably incur large displacement of the structure to the ground ·ind may give adverse effects on the sloshing height. This paper presents the analysis method for fluid-structure-isolator interaction in base-isolated rectangular liquid storage structures. In the method, the irrotational motion of invicid and incompressible ideal fluid is expressed by analytic solutions and the superstructure and isolators are properly modeled by finite element and bilinear model. Free surface sloshing motion, hydrodynamic pressure acting on the wall and structural response are obtained by the presented method.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.676-686
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• 2010

Damage Cases of variously type are reported that the ground subsidence is caused by the underground cavities at structure and construction works in lime stone or abandoned zone. A underground cavities by direct for zone having an effect on structure have been filled with cement agents. But this measure is urgently needed in materials and work methods, because ground water pollution at water down fillings and flow out, ground disturb at high participle, damage of farms and fishery. The research confirm application of filling method and filling materials of environmentally friendly and economical by Hi-FA new materials have both liquidity and viscosity from case reinforcement in APT site, Gunsan.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2041-2046
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• 2008

A frequency-dependent slow-wave factor (SWF) and equivalent circuit model of transmission line with defected ground structures (DGS) is described. Once S-parameters of a DGS transmission line are given, the conventional frequency -independent equivalent circuit elements are extracted using 3dB cutoff and resonant frequencies (Fc and Fo) as the first step. Using the initial equivalent elements and simple transmission line theories, a frequency-dependent equivalent transmission line model is established through an analytical method, and finally the frequency dependent SWF is calculated. The proposed equivalent circuit model and SWF are frequency-dependent and more reliable because even small insertion loss within available passband is considered, while they have been independent of frequency.

• Journal of Photoscience
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• v.10 no.1
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• pp.165-173
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• 2003

m-Phenylene-linked biscarbenes, bisnitrenes and carbenonitrenes can be formed photochemically from appropriate nitrogenous precursors. Generation of such reactive intermediates under matrix-isolation conditions allows for their characterization by spectroscopic techniques such as ESR, UV /vis and IR. The latter method is also useful in characterizing secondary products derived from these reactive intermediates. Computational chemistry methods complement experimental IR data, aiding, thus, in identification of such compounds. In addition electronic structure calculations help in developing qualitative and semi-quantitative models, which can be useful in predicting ground-state multiplicities. The parent systems of m-phenylene-linked carbenes and nitrenes have high-spin ground states, but a switching to lower multiplicity can be achieved by chemical substitution. The ground state and various low-lying excited states of m-phenylenecarbenonitrenes can be reasonably approximated by simple valence-bond depictions. Finally, m-phenylenecarbenonitrenes are photoreactive in the inert matrix isomerizing to cyclopropene derivatives.

• Journal of electromagnetic engineering and science
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• v.15 no.1
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• pp.26-30
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• 2015

In this paper, a simple equivalent circuit model for a defected ground structure (DGS) microstrip line with stepped impedance slot-lines in the ground plane is presented. In addition, an analytic expression for the resonance frequency of the proposed structure is derived. In equivalent circuit modeling, the capacitance and the inductance of the resonance circuit are evaluated from the dimensions of the etched pattern in the ground plane. The resonance frequencies calculated from the proposed method are compared with those obtained with an electromagnetic (EM) simulation.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.634-639
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• 2009

The response displacement method is the most frequently used method for the seismic design of underground structures. Underground structures under seismic loading will tend to deform with the surrounding ground, and thus the structure is designed to accommodate the free-field deformation without loss of its structural integrity. This method is pseudo-static method, and response displacement of surrounding ground are most important steps. In this study, the single cosine method and the equivalent linear analysis are applied to estimate the response displacement of the real sites, and the results of the each method are compared. Response analysis was also performed with respect to bedrock depth. As a results, Equivalent linear analysis result was larger than single cosine method. And, the relative displacement becomes lager according to depth of the bedrock.

• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.223-237
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• 2020

Transmission towers have come to represent one of the most important infrastructures in today's society, which may suffer severe earthquakes during their service lives. However, in the conventional seismic analyses of transmission towers, the towers are normally assumed to be fixed on the ground without considering the effect of soil-structure interaction (SSI) on the pile-supported transmission tower. This assumption may lead to inaccurate seismic performance estimations of transmission towers. In the present study, the seismic response and failure analyses of pile-supported transmission towers considering SSI are comprehensively performed based on the finite element method. Specifically, two detailed finite element (FE) models of the employed pile-supported transmission tower with and without consideration of SSI effects are established in ABAQUS analysis platform, in which SSI is simulated by the classical p-y approach. A simulation method is developed to stochastically synthesize the earthquake ground motions at different soil depths (i.e. depth-varying ground motions, DVGMs). The impacts of SSI on the dynamic characteristic, seismic response and failure modes are investigated and discussed by using the generated FE models and ground motions. Numerical results show that the vibration mode shapes of the pile-supported transmission towers with and without SSI are basically same; however, SSI can significantly affect the dynamic characteristic by altering the vibration frequencies of different modes. Neglecting the SSI and the variability of earthquake motions at different depths may cause an underestimate and overestimate on the seismic responses, respectively. Moreover, the seismic failure mode of pile-supported transmission towers is also significantly impacted by the SSI and DVGMs.

• Journal of the Korean GEO-environmental Society
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• v.13 no.10
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• pp.85-94
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• 2012

Recent development trend of construction projects in the urban area is the efficient use of insufficient land, however caused to difficult construction conditions because of many adjacent structures. This paper presents the case study that analyzed the ground settlement of railroad structure for the double track railway project of Gyeongui line, adjacent to the high rise building under ground excavating for substructure work, considering interaction of soft ground characteristics. Field survey and measurement works were carried out during construction of station and excavation of high rise building, and field data were analyzed to find the source of settlement of platform and railway. In addition, the soil reinforcement and foundation restoration were performed using in-situ injection method, i.e., D-ROG(Digitalized Restoring On Grout) method which filled the pore of bottom and around of foundation with micro-cement.

• Earthquakes and Structures
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• v.17 no.6
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• pp.557-566
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• 2019

The evaluation of the seismic hazard for a given site is to estimate the seismic ground motion at the surface. This is the result of the combination of the action of the seismic source, which generates seismic waves, the propagation of these waves between the source and the site, and site local conditions. The aim of this work is to evaluate the sensitivity of dynamic response of extended structures to spatial variable ground motions (SVGM). All factors of spatial variability of ground motion are considered, especially local site effect. In this paper, a method is presented to simulate spatially varying earthquake ground motions. The scheme for generating spatially varying ground motions is established for spatial locations on the ground surface with varying site conditions. In this proposed method, two steps are necessary. Firstly, the base rock motions are assumed to have the same intensity and are modelled with a filtered Tajimi-Kanai power spectral density function. An empirical coherency loss model is used to define spatial variable seismic ground motions at the base rock. In the second step, power spectral density function of ground motion on surface is derived by considering site amplification effect based on the one dimensional seismic wave propagation theory. Several dynamics analysis of a curved viaduct to various cases of spatially varying seismic ground motions are performed. For comparison, responses to uniform ground motion, to spatial ground motions without considering local site effect, to spatial ground motions with considering coherency loss, phase delay and local site effects are also calculated. The results showed that the generated seismic signals are strongly conditioned by the local site effect. In the same sense, the dynamic response of the viaduct is very sensitive of the variation of local geological conditions of the site. The effect of neglecting local site effect in dynamic analysis gives rise to a significant underestimation of the seismic demand of the structure.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.245-250
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• 2007

The small loop EM method is a fast and convenient geophysical tool which can give shallow subsurface resistivity distribution. It can be a useful alternative of resistivity method in conductive environment. We applied the multi-frequency small loop EM method for the investigation of a soft ground landfill site which was constructed on a tideland since the resistivity of the survey area is extremely low. 3D resistivity distribution was obtained by merging 1D inversion results and shallow subsurface structure can be interpreted. By comparing the result with the drilling log and measured soil resistivity sampled at 16 drill holes, we can get lot of information such as groundwater level, thickness of landfill, salinity distribution, depth to the basement and etc.