• Wind and Structures
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• v.36 no.6
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• pp.379-392
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• 2023

Structural health monitoring is used to ensure the well-being of civil structures by detecting damage and estimating deterioration. Wind flow applies external loads to high-rise buildings, with the horizontal force component of the wind causing structural displacements in high-rise buildings. This study proposes a deep learning-based predictive model for measuring lateral displacement response in high-rise buildings. The proposed long short-term memory model functions as a sequence generator to generate displacements on building floors depending on the displacement statistics collected on the top floor. The model was trained with wind-induced displacement data for the top floor of a high-rise building as input. The outcomes demonstrate that the model can forecast wind-induced displacement on the remaining floors of a building. Further, displacement was predicted for each floor of the high-rise buildings at wind flow angles of 0° and 45°. The proposed model accurately predicted a high-rise building model's story drift and lateral displacement. The outcomes of this proposed work are anticipated to serve as a guide for assessing the overall lateral displacement of high-rise buildings.

• Smart Structures and Systems
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• v.21 no.5
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• pp.637-652
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• 2018

This paper presents a comparative study of displacement measurement using four sensors that are being used in the field: they are a ring gauge, a laser Doppler vibrometer (LDV), a vision-based displacement measurement system (VDMS), and an optoelectronic displacement meter (ODM). The comparative study was carried out on a brand-new high-speed railroad bridge designed to produce displacements within a couple of millimeters under the loading of a high-speed train. The tests were carried out on a single-span steel plate girder bridge two times with different train loadings: KTX and HEMU. The measured displacement is compared as raw and further discussion was made on the measurement noise, peak displacement, and frequency response of four sensors. The comparisonsare summarized to show the pros and cons of the used sensors in measuring displacement at a typical high-speed railroad bridge.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.151-158
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• 2006

Structural health monitoring is concerned with the safety and serviceability of the users of structures, especially for the case of building structures and infrastructures. When considering the safety of a structure, the maximum stress in a member due to live load, earthquake, wind, or other unexpected loadings must be checked not to exceed the stress specified in a code. It will not fail at yield, excessively large displacements will deteriorate the serviceability of a structure. To guarantee the safety and serviceability of structures, the maximum displacement in a structures must be monitored because actual displacement is a direct assessment index on its stiffness. However, no practical method has been reported to monitor the displacement, especially for the case of displacement of high-rise buildings because of not to easy accessive. In this paper, it is studied displacement measuring method of high-rise buildings using LiDAR The method is evaluated by analyzing accuracy of measured displacements for existing building.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.93-98
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• 2003

High speed precision machines have been introduced to the CNC industry in order to improve productivity, shorten the appointed date of delivery and reduce the prime cost. High speed machines have more functions then general machines, and they were proved in performance. The production and sales of the high speed machines have been increased not only in domestic market but also all over the world. Accordingly, machines are faster, there are lots of problems to be solved. One of the most difficult problems is the thermal displacement on the main spindle due to generated heat while the spindle is rotated in high speed. Since the thermal displacement directly effects the quality of the machined parts, utmost efforts to minimize the thermal displacement have to be given from the beginning of designing machines. In practice, variety of methods are attempted and practiced to minimize the thermal displacement such as design of symmetrical frame, adoption of high speed bearings, application of compensation system using non-contact sensor and use of forced circulating lubrication system with oil cooler. Even if these variable methods have been practically used in the industrial field, generated heat has not been Perfectly Prevented lienee, in this paper, the characteristics of thermal displacement were investigated when several kinds of oil were tested for a high speed machine with forced circulating lubrication system within the same atmosphere and under the same conditions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.47-53
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• 2004

High speed precision machines have been introduced to the CNC industry in order to improve productivity, shorten the appointed date of delivery and reduce the prime cost. High speed machines have more functions then general machines, and they were proved in performance. The production and sales of the high speed machines have been increased not only in domestic market but also all over the world. Accordingly, machines are faster, there are lots of problems to be solved. One of the most difficult problems is the thermal displacement on the main spindle due to generated heat while the spindle is rotated in high speed. Since the thermal displacement directly effects the quality of the machined parts, utmost efforts to minimize the thermal displacement have to be given from the beginning of designing machines. In practice, variety of methods are attempted and practiced to minimize the thermal displacement such as design of symmetrical frame, adoption of high speed bearings, application of compensation system using non-contact sensor and use of forced circulating lubrication system with oil cooler. Even if these variable methods have been practically used in the industrial field, generated heat has not been perfectly prevented. Hence, in this paper, the characteristics of thermal displacement were investigated when several kinds of oil were tested for a high speed machine with forced circulating lubrication system within the same atmosphere and under the same conditions.

• 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.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.798-803
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• 2006

The suspension elements like primary coil spring, yaw damper, body to body damper are core parts of high speed railway bogie and the faults relating to these elements are reported recently. Thus, this study is started to analyze the displacements characteristics of suspension elements of high speed railway rolling-stock for the purpose of preventing the faults and developing the maintenance technology for suspension elements like spring and dampers. For this purpose, we made a plan to measure the displacements of the primary coil spring, yaw damper and body to body damper in actual running condition. We developed the measurement device to measure the longitudinal displacement and angular displacement of suspension elements and installed this device to test suspension elements. Test to measure displacements of suspension elements is conducted in service line of high speed railway. The displacement data which is acquired from the test with actual vehicles was analyzed for its maximum displacement depending on the track sections. As a result of analysis, we obtained the displacement trends occurring with the sections and valuable results like maximum values and the displacement distribution.

• 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.28 no.6
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• pp.827-838
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• 2021

The dynamic displacement is considered to be an important indicator of structural safety, and becomes an indispensable part of Structural Health Monitoring (SHM) system for high-speed railway bridges. This paper proposes an indirect strain based dynamic displacement reconstruction methodology for high-speed railway box girders. For the typical box girders under eccentric train load, the plane section assumption and elementary beam theory is no longer applicable due to the bend-torsion coupling effects. The monitored strain was decoupled into bend and torsion induced strain, pre-trained multi-output support vector regression (M-SVR) model was employed for such decoupling process considering the sensor layout cost and reconstruction accuracy. The decoupled strained based displacement could be reconstructed respectively using box girder plate element analysis and mode superposition principle. For the transformation modal matrix has a significant impact on the reconstructed displacement accuracy, the modal order would be optimized using particle swarm algorithm (PSO), aiming to minimize the ill conditioned degree of transformation modal matrix and the displacement reconstruction error. Numerical simulation and dynamic load testing results show that the reconstructed displacement was in good agreement with the simulated or measured results, which verifies the validity and accuracy of the algorithm proposed in this paper.

• Fire Science and Engineering
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• v.30 no.2
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• pp.106-113
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• 2016

Ultra-high pressure positive displacement pump can discharge high pressure water with mass volume, which depends on periodic changes in volume that made by rotation motor. Its high efficiency of discharge is one of the most strong point of positive displacement pump. Due to its simple system structure, it can be miniaturized and lightened. Positive displacement pump can discharge high pressure with stable flow rate, irrespective of pressure fluctuate. This is the reason that positive displacement pump was used instead of centrifugal pump. In this study, shutoff operating system was developed for positive displacement pump to secure safety of high pressure operate. This shutoff system contains controller system, electronic clutch, and relief valve, and each part is mutual supplementation. Speed test was carried out in order to check operation of controller program and electronic clutch and fluid flow, venting experiment of the relief valve. It was confirmed that segment system of ultra-high pressure positive displacement pump is operated.