• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.7-14
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• 2003

In the back analysis of braced excavation based on displacement measurements, the accumulated errors of abnormal displacement caused by unexpected loads are usually observed. To minimize such errors, in this study, displacement increment was used fur back analysis rather than displacement for the conventional method. That is, the increment of sequential displacement is used as the objective function and the back analysis program is developed by taking advantage of sequential linear programming method by modified method of feasible directions. Based on small scale model test, the analysis of proposed method is verified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.428-431
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• 2005

In this paper, the displacement and stress of pile foundation constructed in the soft cohesive soils were measured and investigated at each construction phase. The piles belongs to compressive stress then extension due to lateral flow of soft soils. Battered piles showed different stress state according to construction direction. The lateral displacements of piles radically occurred at the embankment phase.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.229-240
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• 2007

The 3D absolute displacement monitoring system has been developed to analyze the tunnel convergence measured under construction of underground structures and to manage effectively the measured data. The system is comprised of the total station, the anchor-typed target pin and the 3D absolute displacement measurement and management program. In this paper, the types and specifications of the 3D total station were presented. The anchor-typed target pin, an improved model of traditional one, was developed and its sightable distance and measurement accuracy were checked by field tests. Also a 3D absolute displacement measurement and management program, TEMS 3D, was developed to provide some analysis tools including the trend and influence lines. L/C ratio, S/C ratio and the like. The developed system was applied the construction stage of a railway tunnel for testing purpose. It is verified that the developed system is capable of predicting weak zones ahead of tunnel face by comparing with results of TSP (Tunnel Seismic Prediction) survey.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.237-242
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• 2016

This paper introduces a method of measuring the displacement of a cable-stayed bridge using digital image processing (DIP). The validity of the DIP technique was confirmed by comparing the results with those obtained using a displacement meter and ANSYS analysis. The normalized cross-correlation (NCC) coefficient was used. 100 kgf and 200 kgf loading experiments were carried out, which showed that when the displacement is large, the reliability of the DIP technique is increased. That is, when the load was increased from 100 kgf to 200kgf, it decreased from 31% to 14% compared to the ANSYS results and from 14% to 4% compared to the displacement meter results. Therefore, the image processing method is able to measure the displacement sufficiently accurately.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.251-264
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• 2019

The displacement monitoring of unstable block at the rock slope located in the Cheonbuldong valley of Seoraksan National Park was carried out using Terrestrial LiDAR. The rock slopes around Guimyeonam and Oryeon waterfall where rockfall has occurred or is expected to occur are selected as the monitoring section. The displacement monitoring of unstable block at the rock slope in the selected area was performed 5 times for about 7 months using Terrestrial LiDAR. As a result of analyzing the displacement based on the Terrestrial LiDAR scanning, the error of displacement was highly influenced by the interpolation of the obstruction section and the difference of plants growth. To minimize the external influences causing the error, the displacement of unstable block should be detected at the real scanning point. As the result of analyzing the displacement of unstable rock at the rock slope using the Terrestrial LiDAR data, the amount of displacement was very small. Because the amount of displacement was less than the range of error, it was difficult to judge the actual displacement occurred. Meanwhile, it is important to select a section without vegetation to monitor the precise displacement of unstable rock at the rock slope using Terrestrial LiDAR. Also, the PointCloud removal and the mesh model analysis in a vegetation section were the most important work to secure reliability of data.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.1
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• pp.47-53
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• 2001

In this study, it is intended to measure the displacement of a bridge for the safety examination using Digital Close Range Photogrammetry(DCRP). The digital images which were obtained by a digital camera and a CCD camera in load cases was analyzed. In the same condition, the displacements were obtained respectively from sensor, precision level, and film-based images for comparison. As a result, it could be confirmed that the application of DCRP to the safety examination and the movement measurement of the bridge is possible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.423-427
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• 2005

In this paper, the lateral displacement of soft soil was measured in pier structure. The result was compared and investigated with the result of numerical analysis. The lateral displacement of soft soil was affected by lateral flow of soft soil due to embankment rather than settlement, and rapidly occurred at the embankment and preloading phases. The measurement and the numerical analysis showed very similar trend of lateral displacement but the magnitude was larger in numerical analysis than in measurement.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.337-347
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• 2008

Critical strain is a new material property of the ground. Critical strain concept which was established in tunnel engineering can be applied to deformation limits in the ground due to tunneling by using the measured displacement at the tunnel construction site. In this study, quantitative evaluations for the tunnel stability are conducted by analysing the displacement results obtained at the construction field. Especially, critical stain concept was reviewed from a total displacement point of view using the displacements occurring before excavation. As a results, the variation characteristics of the tunnel stability are presented on the critical strain diagram with or without the preceeding displacements.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.6 no.1
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• pp.35-41
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• 1988

In the three dimensional deformation analysis by terrestrial photographs, iterative reweighted similarity transformation method is used for more accurate displacement computation. Also, Bayesian Inference method is used in the detection of unstable points and the analytical method for displacement patterns analysis is proposed in this study. In results, the accuracy of displacement estimation was improved by applying the weights of least absolute method ($\Sigma$｜d｜⇒min) and more accurate detection of displaced points could be achieved by Bayesian Inference. The analytical method in the patterns of displacement proposed in this study could be adapted to the movement analysis of objects wholly or partly.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.286-295
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• 2017

In this study, it is compared various coefficients of subgrade reaction for application of numerical analysis based on measured data by using various theories and empirical formula. The ratio of the maximum and minimum value is 6.80 at the top of wall but it is 1.06 at the maximum displacement point depends on change of calculated coefficient of subgrade reaction. The data of displacement were generally similar considering an increment of a coefficient of subgrade reaction. And the results of comparison of the displacement at the maximum displacement point by numerical analysis and measured data show similar displacement shape.