• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.345-352
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• 1998

Free-field ground motion during earthquake is significantly affected by the local site conditions and the behavior of structure is influenced by ground motion, it is essential to perform the reliable site characterization and to determine the site specific earthquake response. In this study, case study of site specific ground response evaluation was performed at Inchon area. Step by step procedures for site characterization and one-dimensional site response analysis were introduced and the importance of site specific analysis was verified.

• Geomechanics and Engineering
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• v.15 no.3
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• pp.899-910
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• 2018

Terrace deposits are often encountered in portal areas and tunnels with low overburden. They are challenging to excavate considering their great mechanical and spatial heterogeneity and a very high stiffness contrast within the ground. Terrace deposits are difficult to characterize, considering that samples for laboratory testing are almost unfeasible to obtain, and laboratory tests may not be representative due to scale effects. This paper presents the approach taken for their characterization during the design stage and their posterior validation performed during construction. Lessons learned from several tunnels excavated on terrace deposits on the Bogota-Villavicencio road (central-east Colombia), suggest that based on numerical simulations, laboratory testing and tunnel system behaviour monitoring, an observational approach allows engineers to optimize the excavation and support methods for the encountered ground conditions, resulting in a more economic and safe construction.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.584-590
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• 2009

One of the critical design problems involved in deep tunnelling in brittle rock, is the creation of surface spalling damage and breakouts. If weak fault zone is developed in deep tunnel, squeezing problem is added to the problems. According to the results of ground investigation in the study area, hard granitic rockmass and distinguished high angle fault zone are distributed on the tunnel level over 400m depth. To analyse the probability of brittle failure and squeezing, ground characterization with special lab. and field test were carried out. By the results, probability of brittle failures like spalling and rock burst is very low. But squeezing may be probable, if weak fault zone observed surface and drill core is extended to designed tunnel level.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.1-10
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• 1999

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 site specific ground response analysis. In this paper, the procedures of site specific ground response analysis were suggested based on the Korean seismic guideline and the review of state of the art technologies. The concept of ground response analysis was introduced, and the techniques of obtaining soil data for one dimensional equivalent linear analysis which include site investigation planning, field and laboratory testing techniques, deformational characteristics of soils at small to large strains, and site characterization techniques combining field and laboratory test results, were suggested. Finally, the case study was performed at Inchon area following the suggested procedure.

• 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.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.10a
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• pp.70-86
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• 2003

Despite its usability, TCE has been managed as a hazardous material due to the toxicity and many contamination cases were surveyed in some developed countries. U.S.EPA(Kram et al., 2001) suggested DNAPL characterization methods and approaches based on survey experiences at several sites. However, Korea has not the least assessment of contamination and trial of remediation, although there are a lot of doubtable areas where ground water would be contaminated with TCE. In this study, we try to assess the volume and extent of ground water contamination with TCE and delineate the contamination source zones in an industrial area. Ground water in this area flows through fractures and the contaminant TCE has the properties of high volatility, high density and low partitioning to soil material. Thus, we applied a variety of technical approaches to identify the contamination status; documentary, hydrogeochemical, hydrogeological and geological surveys. In addition, additional survey was performed based on the interim findings, which showed that ground water contamination was limited to the relatively small area with high concentrations to the deep place. The contamination source zone is estimated to be the asphalt test institute where a great deal of TCE has been used to analyze the amount of asphalt soluble in TCE since 1984. Based on the contamination characterization and a myriad of documents about ground water remediation, appropriate site remediation management options will be recommended later. This study is now under way and this paper was focused on describing the technical approaches used to achieve the goals of this study.

• Structural Engineering and Mechanics
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• v.34 no.5
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• pp.663-666
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• 2010

The spectral content of ground displacement of the 10 largest last California earthquakes is studied. Specifically, the power spectral density function of the critical horizontal-component record of the closest-to-epicenter station is analyzed in each case. The results permit to state that horizontal ground displacement is a narrow-band process. This fact was previously noticed while trying to solve the large-base-displacement problem in isolated structures and it was fundamental in the solution of this issue; however, these preliminary results were limited in number to enable a statement like the foregoing one. Thus, the broader results presented herein were necessary.

• Earthquakes and Structures
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• v.3 no.5
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• pp.629-647
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• 2012

Multiple acceleration sequences of earthquake ground motions have been observed in many regions of the world. Such ground motions can cause large damage to the structures due to accumulation of inelastic deformation from the repeated sequences. The dynamic analysis of inelastic structures under repeated acceleration sequences generated from simulated and recorded accelerograms without sequences has been recently studied. However, the characteristics of recorded earthquake ground motions of multiple sequences have not been studied yet. This paper investigates the gross characteristics of earthquake records of multiple sequences from an engineering perspective. The definition of the effective number of acceleration sequences of the ground shaking is introduced. The implication of the acceleration sequences on the structural response and damage of inelastic structures is also studied. A set of sixty accelerograms is used to demonstrate the general properties of repeated acceleration sequences and to investigate the associated structural inelastic response.

• Journal of the Society of Disaster Information
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• v.14 no.2
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• pp.130-140
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• 2018

Purpose: In this paper, we propose a design technique for the safety characterization grounding in the construction of the photovoltaic power generation complex which can be useful and useful as an alternative power energy source in our society. In other words, we will introduce the application of safety grounding for each application, which can improve and optimize the reliability of the internal grid from the cell module to the electric room in the photovoltaic power generation complex. Method: We analyze the earth resistivity of the soil in the solar power plant and use the computer program (CDEGS) to analyze the contact voltage and stratospheric voltage causing the electric shock, and propose the calculation and calculation method of the safety ground. In addition, we will discuss the importance of semi-permanent ground electrode selection in consideration of soil environment. Results: We could obtain the maximum and minimum value of ground resistivity for each of the three areas of the data measured by the Wenner 4 - electrode method. The measured data was substituted into the basic equation and calculated with a MATLAB computer program. That is, it can be determined that the thickness of the minimum resistance value is the most favorable soil environment for installing the ground electrode. Conclusion: Through this study, we propose a grounding system design method that can suppress the potential rise on the ground surface in the inner grid of solar power plant according to each case. However, the development of smart devices capable of accumulating big data and a monitoring system capable of real-time monitoring of seismic changes in earth resistances and grounding systems should be further studied.

• Geomechanics and Engineering
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• v.33 no.5
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• pp.439-451
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• 2023

The construction of shield tunnelling in urban sites is facing serious risks from complex and changeable underground conditions. Construction problems in the sand-clay mixed ground have been more reported in recent decades for its poor control of soil loss in tunnel face, ground settlement and supporting pressure. Since the limitations of observation methods, the conventional physical modelling experiments normally simplify the tunnelling to a plane strain situation whose results are not reliable in mixed ground cases which exhibit more complicated responses. We propose a new method for the study of the mixed ground tunnel through which mixed lays are simulated with transparent soil surrogates exhibiting different mechanical properties. An experimental framework for the transparent soil modelling of the mixed ground tunnel was established incorporated with the self-developed digital image correlation system (PhotoInfor). To understand better the response of face stability, ground deformation, settlement and supporting phenomenon to tunnelling excavation in the sand-clay mixed ground, a series of case studies were carried out comparing the results from cases subjected to different buried depths and mixed phenomenon. The results indicate that the deformation mode, settlement and supporting phenomenon vary with the mixed phenomenon and buried depth. Moreover, a stratigraphic effect exists that the ground movement around mixed face reveals a notable difference.