• Geotechnical Engineering
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• v.14 no.6
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• pp.139-151
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• 1998

SI anchor means the soil improvement anchor. The ground for supporting anchor is improved by JSP, and as a result, SI anchor body has about 80cm in diameter. SI anchor shows high pullout resistance by the frictional force between anchor body and ground, and the bearing capacity of anchor body. Especially the frictional force increases very much with increasing diameter of anchor body improved by JBP. In this study, model and field tests are made to analyse the mechanism of pullout resistance of SI anchor. Through model tests for the SI anchor in air dried sandy ground, strain fields of ground around SI anchor surface are analysed by a photo analysis method using the latex membrane on the wall of soil tank. The results of field tests are analysed by the strains measured by 10 strain gages attached on the inner wall of specially designed PVC pipe embedded in anchor body, and the strains of anchor body are also measured in the model tests.

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.717-721
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• 2006

• Korean Journal of Agricultural Science
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• v.37 no.3
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• pp.491-499
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• 2010

This study was carried out to investigate the consolidation characteristics of the remolded clay by the oedometer and the constant rate of strain(CRS) consolidation tests. As the rate of strain increases, the settlement rapidly decreased. As the ratio of the sand in the specimen increases, its effect on the rate of strain to the settlement was reduced. As the effective stress increased, the void ratio decreased, while the rate of strain increased, it did not show a clear variation. The reduction of the void ratio was shown to be less than the oedometer test. The coefficient of vertical consolidation with effective stress showed very large variation around preconsolidation stress, but the rate of strain did not provide significant effects. The rate of strain with effective stress gradually decreased at all tests and mixed ratio of sand. The rate of strain at the constant rate of strain tests showed smaller than in the oedometer test. The coefficient of consolidation at the constant rate of strain tests showed much more increase than in the oedometer test. The ratio of the vertical coefficient of consolidation by the odometer and the constant rate of strain tests showed a large difference according to various tests method and mixing ratio. Therefore, it is recommended that careful attention should be paid to designing the soft ground improvement.

• Earthquakes and Structures
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• v.8 no.3
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• pp.541-553
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• 2015

Structural Health Monitoring (SHM) systems can provide valuable information regarding the safety of structures during and after ground motions which can be used by authorities to reduce post-earthquake hazards. Strain gages as a key element play an important role in the success of SHM systems. Reducing the number of required strain gages while keeping the efficiency of SHM system not only can reduce the cost of structural health monitoring but also avoids storage and process of uninformative data. In this study, a method based on performance based seismic design of structures is proposed for ideal placement of stain gages in structures. The robustness and efficiency of the proposed method is demonstrated through installation of strain gages on an Airport Traffic Control (ATC) Tower. The obtained results show that the number of required strain gages decrease significantly.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.16-23
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• 2013

It is important that proving ground damage is correlated with target customer usage. This paper describes the test mode for durability test of active suspension control system for proving ground correlation and optimization. Acceleration, strain, wheel force and other types of data are collected on a vehicle as it traverses different proving ground surfaces. The primary objective of the analysis is to determine which mixture of proving ground surfaces offers the best representation of customer usage while minimizing the total test time. And durability testing offers the best way to assess the capability of a product to reach its reliability target. The test should be representative of the real environmental load and replicate the same customer usage.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.249-256
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• 2006

New infrastructures and buildings are being constructed increasingly in congested urban areas, and excavation-induced ground movements often cause distortion and damage to adjacent buildings. Protection of adjacent structures occupies a major part of the cost, schedule and third-party impacts of urban development. To limit damage or mitigate their effects on nearby structures, it is highly important to understand the whole mechanism from excavation to building damage, and to estimate building damage reliably before excavation and provide appropriate measures. This paper investigates the effects of excavation-induced ground movements on nearby structures, considering soil-structure interactions for ground and structures, and a building damage criterion, which is based on the state of strain, is proposed. The criterion is compared with other existing damage estimation criteria and a procedure is finally provided for estimating building damage due to excavation-induced ground movements.

• Geophysics and Geophysical Exploration
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• v.19 no.3
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• pp.153-163
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• 2016

In order to prevent ground collapses by groundwater level drawdown, we need to understand the groundwater flow and also make an analytical approach to the cause of the collapses. In this study, we used the result of the soil lab tests to compare and review the suitability of the various interaction equations about the relation between volumetric water content and the dielectric constant. In addition, using GPR (Ground-Penetrating Radar), we reviewed the possibility of calculating an estimate of dielectric constant. Lastly, we applied seepage analysis and stress-strain analysis to the sandy ground given by ground excavation. In comparison with the previous result of the soil lab tests, we similarly predicted the suction of unsaturated soil from results of stress-strain analysis considered the seepage force for the unsaturated soil.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.577-587
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• 2021

Room and Pillar method is an underground facility construction method that maximizes the strength of the in-situ ground. In order to secure the safety of the underground space, it is necessary to secure the safety of the room actually used in addition to the safety of pillar of the room and Pillar method. In this study, the evaluation method for the safety of the room and rock pillar in the room and pillar method was studied through numerical analysis. Numerical analysis was performed for a total of 125 cases using ground conditions, pillar width, and room width as parameters, and the results were derived. As for the safety factor of the pillar, it was confirmed that the safety factor increased when the strength of the ground increased, and it was confirmed that the increment in the safety factor decreased when the width of the pillar was widened. The room strain was evaluated by applying the Critical strain. As the width of the pillar became narrower, the Critical strain was higher, and as the width of the room became smaller, the Critical strain was smaller. As a result of the correlation analysis between the safety factor of the pillar and the room strain, it was possible to derive the upper limit of the room strain that can secure the standard safety factor of the pillar according to the width of the pillar. It is judged that the results derived from this study can be used as a guideline to secure the safety of the room when the actual design is performed in consideration of the ground conditions and room width.

• 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.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.201-217
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• 1999

Bearing capacity of soil can be improved by several conventional ground improvement techniques like stabilization and compaction. In recent time, the use of reinforced soil has become popular due to the availability of durable strong geosynthetic materials. In this papers, through the laboratory model tests on sandy ground reinforced by mats about the strip footing under plane strain condition, the effects of bearing capacity improvement and behaviour of sandy ground were observed. And bearing capacities calculated by proposed method and measured by tests were compared.