• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.183-191
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• 2018

In this study a traffic volume dependent displacement estimation model for Gwangan Bridge was developed using bridge monitoring big data. Traffic volume data for four different vehicle types and the vertical displacement data in the central position of the Gwangan Bridge were used to develop and validate the estimation model. Two statistical estimation models were developed using multiple regression analysis (MRA) and principal component analysis (PCA). Estimation performance of those two models were compared with actual values. The results show that both the MRA and the PCA based models are successfully estimating the vertical displacement of Gwangan Bridge. Based on the results, it is concluded that the developed model can effectively be used to predict the traffic volume dependent displacement behavior of Gwangan Bridge.

• Journal of Korea Game Society
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• v.9 no.6
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• pp.171-178
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• 2009

Multiple layer displacement mapping methods are able to represent more complex and general geometries which cannot be presented by single layer displacement mapping methods, and provide a realistic scene to digital contents such as 3D games and movies with relatively low costs. However, as we use more layers for details, data space is wasted more because lower layers have less displacement data than higher layers. In this paper, we suggest a lossless compression and rendering method of a multiple layer displacement map. Since we compress the map without data loss, the proposed method provides the same quality as the rendering result that uses an original multiple layer displacement map.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1250-1251
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• 2022

Measuring management is an important part of preventing the collapse of retaining walls in advance by evaluating their stability with a variety of measuring instruments. The current work of measuring management requires considerable human and material resources since measurement companies need to install measuring instruments at various places on the retaining wall and visit the construction site to collect measurement data and evaluate the stability of the retaining wall. It was investigated that the applicability of the current work of measuring management is poor at small and medium-sized urban construction sites(excavation depth<10m) where measuring management is not essential. Therefore, the purpose of this study is to develop a laser sensor-based hardware to support the wall displacement measurements and their control software applicable to small and medium-sized urban construction sites. The 2D lidar sensor, which is more economical than a 3D laser scanner, is applied as element technology. Additionally, the hardware is mounted on the corner strut of the retaining wall, and it collects point cloud data of the retaining wall by rotating the 2D lidar sensor 360° through a servo motor. Point cloud data collected from the hardware can be transmitted through Wi-Fi to a displacement analysis device (notebook). The hardware control software is designed to control the 2D lidar sensor and servo motor in the displacement analysis device by remote access. The process of analyzing the displacement of a retaining wall using the developed hardware and software is as follows: the construction site manager uses the displacement analysis device to 1)collect the initial point cloud data, and after a certain period 2)comparative point cloud data is collected, and 3)the distance between the initial point and comparison point cloud data is calculated in order. As a result of performing an indoor experiment, the analyses show that a displacement of approximately 15 mm can be identified. In the future, the integrated system of the hardware designed here, and the displacement analysis software to be developed can be applied to small and medium-sized urban construction sites through several field experiments. Therefore, effective management of the displacement of the retaining wall is possible in comparison with the current measuring management work in terms of ease of installation, dismantlement, displacement measurement, and economic feasibility.

• Smart Structures and Systems
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• v.17 no.4
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• pp.647-667
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• 2016

In this paper, dynamic displacement is estimated with high accuracy by blending high-sampling rate acceleration data with low-sampling rate displacement measurement using a two-stage Kalman estimator. In Stage 1, the two-stage Kalman estimator first approximates dynamic displacement. Then, the estimator in Stage 2 estimates a bias with high accuracy and refines the displacement estimate from Stage 1. In the previous Kalman filter based displacement techniques, the estimation accuracy can deteriorate due to (1) the discontinuities produced when the estimate is adjusted by displacement measurement and (2) slow convergence at the beginning of estimation. To resolve these drawbacks, the previous techniques adopt smoothing techniques, which involve additional future measurements in the estimation. However, the smoothing techniques require more computational time and resources and hamper real-time estimation. The proposed technique addresses the drawbacks of the previous techniques without smoothing. The performance of the proposed technique is verified under various dynamic loading, sampling rate and noise level conditions via a series of numerical simulations and experiments. Its performance is also compared with those of the existing Kalman filter based techniques.

• Smart Structures and Systems
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• v.6 no.9
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• pp.1025-1039
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• 2010

Measuring displacement response for civil structures is very important for assessing their performance, safety and integrity. Recently, video-based techniques that utilize low-cost high-resolution digital cameras have been developed for such an application. These techniques however have relatively low sampling frequency and the results are usually contaminated with noises. In this study, an integrated visual-inertial measurement method that combines a monocular videogrammetric displacement measurement technique and a collocated accelerometer is proposed for displacement and velocity measurement of civil engineering structures. The monocular videogrammetric technique extracts three-dimensional translation and rotation of a planar target from an image sequence recorded by one camera. The obtained displacement is then fused with acceleration measured from a collocated accelerometer using a multi-rate Kalman filter with smoothing technique. This data fusion not only can improve the accuracy and the frequency bandwidth of displacement measurement but also provide estimate for velocity. The proposed measurement technique is illustrated by a shake table test and a pedestrian bridge test. Results show that the fusion of displacement and acceleration can mitigate their respective limitations and produce more accurate displacement and velocity responses with a broader frequency bandwidth.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.8-13
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• 2008

At present many research projects on high-speed spindles are being conducted. These projects require a measurement technique which includes heat expansion, vibration and displacement measurement according to angular velocity. This paper presents the development of a measurement system for high-speed spindle displacement. The measurement system is based on $LabView^{(R)}$ and features the following sensors: optical sensor which reacts to the position of a marker on the spindle and enables two Laser Displacement Sensors(LDS). These Laser Displacement Sensors send their data to a DAQ(Data Acquisition Device). It is important that the delay time caused by the response times of the sensors as well as the sampling rate of the DAQ is considered because the spindle revolves at very high speeds.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3205-3214
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• 2022

The aim of this study is to provide a clear and accessible method to obtain accurate true-stress strain data, and to extend the limited material data beyond the ultimate tensile strength (UTS) for AISI 304L. AISI 304L is used for the outer construction for some types of nuclear transport packages, due to its post-yield ductility and high failure strain. Material data for AISI 304L beyond UTS is limited throughout literature. 3D digital image correlation (DIC) was used during a series of uniaxial tensile experiments. Direct method extracted data such as true strain and instantaneous cross-sectional area throughout testing such that the true stress-strain response of the material up to failure could be created. Post processing of the DIC data has a considerable effect on the accuracy of the true stress-strain data produced. Influence of subset size and smoothing of data was investigated by using finite element analysis to inverse model the force displacement response in order to determine the true stress strain curve. The FE force displacement response was iteratively adapted, using subset size and smoothing of the DIC data. Results were validated by matching the force displacement response for the FE model and the experimental force displacement curve.

• Tunnel and Underground Space
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• v.6 no.4
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• pp.287-297
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• 1996

Input data play an important role in numerical analyses. However, it is difficult to obtain appropriate data for many reasons. In order to overcome those difficulties, an automatic MPBX(Multi-Position Borehole Extensometer) monitoring system is developed. This system can be applied to the analyses of measured data which include evaluation of the stabiliyt, efficiency of construction and the validity of numerical analyses. At first, the MPBX among field measurement tools is considered in this study. Also, 3-dimension finite element analyses are carried out to verify the influence of geological conditions and excavation sequence on the MPBX displacement. The effect of geological conditons on the displacement can be estimated qualitatively qualitavely from the measured data by plotting displacement vs. depth.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.1065-1073
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• 2002

A new damage identification technique using static displacement data is developed to assess the structural integrity of bridge structures. In the conventional damage assessment techniques using dynamic response, it is usually difficult to obtain a significant natural frequencies variation from the measured data because the natural frequencies variation is intrinsically not sensitive to the damage of a bridge. In this proposed identification method, the stiffness reduction of the bridges can be estimated using the static displacement data measured periodically and a specific loading test is not required. The static displacement data due to the dead load of the bridge structure can be measured by devices such as a laser displacement sensor. In this study, structural damage is represented by the reduction in the elastic modulus of the element. The damage factor of the element is introduced to estimate the stiffness reduction of the bridge under consideration. Finally, the proposed algorithm is verified using various numerical simulation and compared with other damage identification method. Also, the effect of noise and number of damaged elements on the identification are investigated. The results show that the proposed algorithm is efficient for damage identification of the bridges.

• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.25-33
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• 2012

In this study, gathered measuring data at fields constructed by IPS(Innovative Prestressed Support) system controls the ground displacement and improves the constructability of earth work and structure work greatly, and compared with horizontal displacement calculated by Elasto-plastic analysis program(EXCAV/W). As the result, displacement of calculated by pre-loading data is reduced 13.2% average of general method, and measuring displacement is also reduced 26.7% average of general method. Therefore that IPS system is more safe than conventional strut method in contrast to displacement of underground wall. In addition, horizontal displacement is reduced through the pre-loading effect used by IPS system.