• Earthquakes and Structures
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• 제4권5호
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• pp.557-585
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• 2013

The recent huge earthquake ground motion records in Japan result in the reconsideration of seismic design forces for nuclear power stations from the view point of seismological research. In addition, the seismic design force should be defined also from the view point of structural engineering. In this paper it is shown that one of the occurrence mechanisms of such large acceleration in recent seismic records (recorded in or near massive structures and not free-field ground motions) is due to the interaction between a massive building and its surrounding soil which induces amplification of local mode in the surface soil. Furthermore on-site investigation after earthquakes in the nuclear power stations reveals some damages of soil around the building (cracks, settlement and sand boiling). The influence of plastic behavior of soil is investigated in the context of interaction between the structure and the surrounding soil. Moreover the amplification property of the surface soil is investigated from the seismic records of the Suruga-gulf earthquake in 2009 and the 2011 off the Pacific coast of Tohoku earthquake in 2011. Two methods are introduced for the analysis of the non-stationary process of ground motions. It is shown that the non-stationary Fourier spectra can detect the temporal change of frequency contents of ground motions and the displacement profile integrated from its acceleration profile is useful to evaluate the seismic behavior of the building and the surrounding soil.

• Geomechanics and Engineering
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• 제9권2호
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• pp.169-193
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• 2015

This paper is the second part of the study for determining the seismic behavior of soil systems. The aim of this part is to present solution approaches for determining seismic site amplification. For this purpose, two solution techniques are used. The first technique is equivalent linear analysis which is mostly used in literature. The other technique is real time parameter updating approach and this approach uses the possibilities of Simulink effectively. A graphical user interfaced (GUI) program called DTASSA standing for Discrete-Time Analysis of Seismic Site Amplification is developed. In DTASSA, automatic block diagram producing system is developed and seismic site amplification for multiple soil layers may easily be investigated in real time. Numerical applications have been carried out to check the reliability of developed algorithm. The results of DTASSA are compared with SUA, EERA and NERA programs for the particular example problems.

• Geomechanics and Engineering
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• 제8권5호
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• pp.663-674
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• 2015

Many seismically vulnerable regions in India and worldwide are located on deep soil deposits which extend to several hundred meters of depth. It has been well recognized that the earthquake shaking is altered by geological conditions at the location of building. As seismic waves propagates through uppermost layers of soil and rock, these layers serve as filter and they can increase the duration and amplitude of earthquake motion within narrow frequency bands. The amplification of these waves is largely controlled by mechanical properties of these layers, which are function of their stiffness and damping. Stiffness and damping are further influenced by soil type and thickness. In the current study, an attempt has been made to study the seismic site response of deep soils. Three hypothetical homogeneous soil models (e.g., soft soil, medium soil and hard soil) lying on bedrock are considered. Depth of half space is varied from 30 m to 2,000 m in this study. Controlled synthetic motions are used as input base motion. One dimensional equivalent linear ground response analyses are carried out using a computer package DEEPSOIL. Conventional approach of analysing up to 30 m depth has been found to be inadequate for deep soil sites. PGA values are observed to be higher for deeper soil profiles as compared to shallow soil profiles indicating that deeper soil profiles are more prone to liquefaction and other related seismic hazards under earthquake ground shaking. The study recommends to deal the deeper soil sections more carefully for estimating the amplification factors for seismic hazard assessment at the surface.

• Geomechanics and Engineering
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• 제3권3호
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• pp.189-206
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• 2011

Amplification based on empirical relations is widely used for seismic microzonation of urban centers. Amplifications are used to represent the site effects of a particular soil column. Many empirical correlations are available to estimate the amplification of seismic waves. These correlations are based on the ratio of shear wave velocity of foundation/rock to soil velocity or 30 m equivalent shear wave velocity ($Vs^{30}$) and are developed considering deep soil data. The aim of this work is to examine the applicability of available amplification relations in the literature for shallow engineering bedrock sites by carrying out site response studies. Shear wave velocity of thirteen sites having shallow engineering bedrock have been selected for the study. In these locations, the depth of engineering bedrock (> 760 ${\pm}$ 60 m/s) is matched with the drilled bore hole. Shear wave velocity (SWV) has been measured using Multichannel Analysis of Surface Wave survey. These sites are classified according to the National Earthquake Hazards Reduction Program (NEHRP) classification system. Amplifications for an earthquake are arrived for these sites using empirical relations and measured SWV data. Site response analysis has been carried out in SHAKE using SWV and using synthetic and real earthquake data. Amplification from site response analysis and empirical relations are compared. Study shows that the amplification arrived using empirical relations does not match with the site response amplification. Site response amplification is much more than empirical values for same shear wave velocity.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.98-107
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• 2000

Free-field ground motion during earthquake is significantly affected by the local site conditions and it is essential for the seismic design to perform the ground response analysis In this study, ground response analyses based on the equivalent linear method were carried out to evaluate the effects of various ground conditions on the site amplification. Four major factors including the depth of the site(very soft and dense soil), the impedance ratio between soil layer and bed rock, linear analysis versus equivalent linear analysis, and the location of soft soil layer were deeply discussed. Based on the analysis results, the importance of various local site conditions on the site amplification was emphasized.

• Journal of Microbiology and Biotechnology
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• 제16권10호
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• pp.1561-1569
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• 2006

Denaturing gradient gel electrophoresis (DGGE) is one of the most frequently used methods for analysis of soil microbial community structure. Unbiased PCR amplification of target DNA templates is crucial for efficient detection of multiple microbial populations mixed in soil. In this study, DGGE profiles were compared using different pairs of primers targeting different hypervariable regions of thirteen representative soil bacteria and clones. The primer set (1070f-1392r) for the E. coli numbering 1,071-1,391 region could not resolve all the 16S rDNA fragments of the representative bacteria and clones, and moreover, yielded spurious bands in DGGE profiles. For the E. coli numbering 353-514 region, various forward primers were designed to investigate the efficiency of PCR amplification. A degenerate forward primer (F357IW) often yielded multiple bands for a certain single 16S rDNA fragment in DGGE analysis, whereas nondegenerate primers (338f, F338T2, F338I2) differentially amplified each of the fragments in the mixture according to the position and the number of primer-template mismatches. A forward primer (F352T) designed to have one internal mismatch commonly with all the thirteen 16S rDNA fragments efficiently produced and separated all the target DNA bands with similar intensities in the DGGE profiles. This primer set F352T-519r consistently yielded the best DGGE banding profiles when tested with various soil samples. Touchdown PCR intensified the uneven amplification, and lowering the annealing temperature had no significant effect on the DGGE profiles. These results showed that PCR amplification bias could be much improved by properly designing primers for use in fingerprinting soil bacterial communities with the DGGE technique.

• 전산구조공학
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• 제1권2호
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• pp.91-100
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• 1988

최근 구조물과 지반간의 상호작용이 원자력 발전시설, 해상구조물, 기계기초 등에 대한 내진설계시 매우 중요하다는 것이 일반화되고 있다. 그러나 지금까지 구조물 내진설계시 이러한 구조물이나 지반의 특성이 무시됐었다. 내진설계상 구조물 밑에 있는 지반에 의한 세가지 주된 영향은 Soil Amplification, Kinematic Interaction과 Inertial Interaction이다. 이 논문에서는 반지하구조물 내진설계시 필요한 지반거동을 Soil Amplification과 Kinematic Interaction을 고려하여 구하였으며, 1971년 San Fernando 지진기록으로부터 그 특성을 실제적으로 입증하였다.

• The Plant Pathology Journal
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• 제33권2호
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• pp.184-192
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• 2017

Tylenchulus semipenetrans is an important and widespread plant-parasitic nematode of citrus worldwide and can cause citrus slow decline disease leading to significant reduction in tree growth and yield. Rapid and accurate detection of T. semipenetrans in soil is important for the disease forecasting and management. In this study, a loop-mediated isothermal amplification (LAMP) assay was developed to detect T. semipenetrans using DNA extracted from soil. A set of five primers was designed from the internal transcribed spacer region (ITS1) of rDNA, and was highly specific to T. semipenetrans. The LAMP reaction was performed at $63^{\circ}C$ for 60 min. The LAMP product was visualized directly in one reaction tube by adding SYBR Green I. The detection limit of the LAMP assay was $10^{-2}J2/0.5g$ of soil, which was 10 times more sensitive than conventional PCR ($10^{-1}J2/0.5g$ of soil). Examination of 24 field soil samples revealed that the LAMP assay was applicable to a range of soils infested naturally with T. semipenetrans, and the total assay time was less than 2.5 h. These results indicated that the developed LAMP assay is a simple, rapid, sensitive, specific and accurate technique for detection of T. semipenetrans in field soil, and contributes to the effective management of citrus slow decline disease.

• Geomechanics and Engineering
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• 제9권2호
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• pp.145-167
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• 2015

Digital simulation has recently become the preferred method for designing complex and dynamic systems. Simulation packages provide interactive, block-diagram environment for modeling and simulating dynamic models. The block diagrams in simulation models are flowcharts which describe the components of dynamic systems and their interaction. This paper is the first part of the study for determining the seismic behavior of soil systems. The aim of this part is to present the constructed block diagrams for discrete-time analysis of seismic site amplification in layered media for vertically propagating shear waves. Detailed block diagrams are constructed for single and multiple soil layers by considering wave propagation with and without damping, respectively. The block diagrams for recursive filter to model attenuation in discrete-time form are also constructed. Finite difference method is used for strain calculation. The block diagrams are developed by utilizing Simulink which is a software add-on to Matlab.

• Earthquakes and Structures
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• 제14권4호
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• pp.285-295
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• 2018

In this study, the effect of local site conditions (site class and site amplifications) and structural variability are investigated on fragility functions of typical building structures. The study area is chosen as Eastern Turkey. The fragility functions are developed using site-specific uniform hazard spectrum (UHS). The site-specific UHS is obtained based on simulated ground motions. The implementation of ground motion simulation into seismic hazard assessment has the advantage of investigating detailed local site effects. The typical residential buildings in Erzincan are represented by equivalent single degree of freedom systems (ESDOFs). Predictive equations are accomplished for structural seismic demands of ESDOFs to derive fragility functions in a straightforward manner. To study the sensitivity of fragility curves to site class, two sites on soft and stiff soil are taken into account. Two alternative site amplification functions known as generic and theoretical site amplifications are examined for these two sites. The reinforced concrete frames located on soft soil display larger fragilities than those on stiff soil. Theoretical site amplification mostly leads to larger fragilities than generic site amplification more evidently for reinforced concrete buildings. Additionally, structural variability of ESDOFs is generally observed to increase the fragility especially for rigid structural models.