• Title/Summary/Keyword: displacement monitoring

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A study on the improvement plan for precision safety diagnosis and seismic repair and reinforcement measures according to seismic performance evaluation (내진성능평가에 따른 정밀안전진단 및 내진 보수보강 조치의 개선방안 연구)

  • Kim, Jang-Ook
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.04a
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    • pp.87-88
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    • 2022
  • For an earthquake-safe urban environment, the Republic of Korea conducts seismic performance evaluation in accordance with laws and guidelines to assign safety ratings and implement necessary management measures such as repairs and reinforcements. In the seismic performance evaluation result, structures lacking in preparation for earthquakes are prioritized and classified into measures such as repair, reinforcement, or careful observation to respond to physical risks such as earthquakes. Such repair and reinforcement work is not a one-time thing, but it is necessary to further enhance the effect through continuous follow-up observation. In this study, the location of the vertical and horizontal displacement measuring part of the construction part is displayed so that the post-construction status of the reinforcement construction part can be visually checked by identifying the problems in the process of post-monitoring in 2022 for the maintenance and reinforcement work of local governments' public facilities carried out in 2021. We propose a plan to institutionalize the installation of, inspection tools, and crack gauges at certain locations in the construction department, and to have facility managers periodically inspect and manage them with a smartphone program or the 'Facility Autonomous Safety Inspection' app.

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Deformation estimation of plane-curved structures using the NURBS-based inverse finite element method

  • Runzhou You;Liang Ren;Tinghua Yi ;Hongnan Li
    • Structural Engineering and Mechanics
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    • v.88 no.1
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    • pp.83-94
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    • 2023
  • An accurate and highly efficient inverse element labelled iPCB is developed based on the inverse finite element method (iFEM) for real-time shape estimation of plane-curved structures (such as arch bridges) utilizing onboard strain data. This inverse problem, named shape sensing, is vital for the design of smart structures and structural health monitoring (SHM) procedures. The iPCB formulation is defined based on a least-squares variational principle that employs curved Timoshenko beam theory as its baseline. The accurate strain-displacement relationship considering tension-bending coupling is used to establish theoretical and measured section strains. The displacement fields of the isoparametric element iPCB are interpolated utilizing nonuniform rational B-spline (NURBS) basis functions, enabling exact geometric modelling even with a very coarse mesh density. The present formulation is completely free from membrane and shear locking. Numerical validation examples for different curved structures subjected to different loading conditions have been performed and have demonstrated the excellent prediction capability of iPCBs. The present formulation has also been shown to be practical and robust since relatively accurate predictions can be obtained even omitting the shear deformation contributions and considering polluted strain measures. The current element offers a promising tool for real-time shape estimation of plane-curved structures.

Measurement of Joint-Orientation and Monitoring of Displacement in Tunnel using 3D Laser Scanning System (3차원 레이저 스캐닝 시스템을 이용한 불연속면의 방향성 측정과 터널 변위 모니터링)

  • Shon, Ho-Woong;Oh, Seok-Hoon;Kim, Young-Kyung
    • Journal of the Korean Geophysical Society
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    • v.9 no.1
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    • pp.47-62
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    • 2006
  • More than 70% of Korean Peninsula is consisted of mountains, so that lots of roads, rail-roads and tunnel,which play a pivotal role in the industry activity, are existed along the rock-slope and in the rock-mass. Thus,it is urgent that tegration of management system through the optimum survey and design of rock-slope excavation, proper stabilization method and database of rock-slope. However, conventional methods have shortcoming with the economy of survey time and human resources, and the overcome of difficulties of approach to the in-situ rock-slope. To overcome the limitation of conventional method, this paper proposed the development of remote measurement system using Terrestrial Laser Scanning System. The method using Terrestrial 3D Laser Scanning System, which can get 3D spatial information on the rock-slope and2)Dept. Geosystem Engineering, Kangwon National University, Korea tunnel, has an advantage of reduction of measurement time and the overcome of difficulties of approach to the in-situ rock-slope/dam/tunnel. In the case of rock-slope, through the analysis of 3D modeling of point-cloud by Terrestrial Laser Scanning System, orientation of discontinuity, roughness of joint surface, failure shape and volume were successively achieved. in the case of tunnel face, through reverse-engineering, monitoring of displacement was possible.

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A Study on the Optimization Period of Light Buoy Location Patterns Using the Convex Hull Algorithm (볼록 껍질 알고리즘을 이용한 등부표 위치패턴 최적화 기간 연구)

  • Wonjin Choi;Beom-Sik Moon;Chae-Uk Song;Young-Jin Kim
    • Journal of Navigation and Port Research
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    • v.48 no.3
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    • pp.164-170
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    • 2024
  • The light buoy, a floating structure at sea, is prone to drifting due to external factors such as oceanic weather. This makes it imperative to monitor for any loss or displacement of buoys. In order to address this issue, the Ministry of Oceans and Fisheries aims to issue alerts for buoy displacement by analyzing historical buoy position data to detect patterns. However, periodic lifting inspections, which are conducted every two years, disrupt the buoy's location pattern. As a result, new patterns need to be analyzed after each inspection for location monitoring. In this study, buoy position data from various periods were analyzed using convex hull and distance-based clustering algorithms. In addition, the optimal data collection period was identified in order to accurately recognize buoy location patterns. The findings suggest that a nine-week data collection period established stable location patterns, explaining approximately 89.8% of the variance in location data. These results can improve the management of light buoys based on location patterns and aid in the effective monitoring and early detection of buoy displacement.

A study on monitoring the subsidence of the gas utilities using GPS techniques (GPS를 이용한 가스설비 침하 감시 기술 연구)

  • Cho S.H.;Jeon K.S.;Park P.H.;Park J.U.;Joh J.H.
    • Journal of the Korean Institute of Gas
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    • v.3 no.2 s.7
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    • pp.53-61
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    • 1999
  • The safety of gas utilities is intimidated by many causes. Among them, subsidence is a dominant cause to decrease the safety of gas utilities. So it is very important to monitor the displacement of subsidence. The purpose of this study is to on-line monitor the subsidence of gas utilities using Static GPS(Global Positioning System)technique. Static GPS technique, which is one of various GPS techniques and originally applied to monitor the crustal activity, was applied for two gas station in Korea Gas Corporation. Prior to applying this technique to the field, i.e, gas station, a preliminary test was peformed to confirm the accuracy of this technique. As a result, it was proved that this technique can measure the displacement of gas utilities three dimensionally by sub-millimeter. After getting confirmation of GPS technique, we applied this technique for two gas stations and monitored the amount of subsidence during 5 months. As a result of field test, we can conclude that the gas stations was subsiding several millimeters in a year.

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Prediction of Change in Ground Condition Ahead of Tunnel Face Using Three-dimensional Convergence Analysis (터널 3차원 내공변위의 해석을 통한 막장전방 지반상태변화 예측)

  • 김기선;김영섭;유광호;박연준;이대혁
    • Tunnel and Underground Space
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    • v.13 no.6
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    • pp.476-485
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    • 2003
  • The purpose of this study is to present an analysis method for the prediction of the change of ground conditions. To this end, three-dimensional convergence displacements is analyzed in several ways to estimate the trend of displacement change. Three-dimensional arching effect is occurred around the unsupported excavation surface including tunnel face when a tunnel is excavated in a stable rock mass. If the ground condition ahead of tunnel face changes or a weak fracture zone exists a specific trend of displacement change is known to be occurred from the results of the existing researches. The existence of a discontinuity, whose change in front of the tunnel face, can be predicted from the ratio of L/C (longitudinal displacement at crown divided by settlement at crown) etc. Therefore, the change of ground condition and the existence of a fracture zone ahead of tunnel face can be predicted by monitoring three-dimensional absolute displacements during excavation, and applying the methodology presented in this study.

Ground Subsidence Measurements of Noksan National Industrial Complex using C-band Multi-temporal SAR images (C-밴드 다중시기 SAR 위성 영상을 이용한 녹산국가산업단지 일대의 지반침하 관측)

  • Cho, Minji;Lee, Chang-Wook
    • Korean Journal of Remote Sensing
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    • v.30 no.2
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    • pp.161-172
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    • 2014
  • Established in the lower reaches of the Nakdong river in Busan, the Noksan national industrial complex is one of the deepest soft ground areas in Korea. In case of the costal landfill having deep soft ground, there is a significant residual settlement over a long period of time. In this study, there was observed ground subsidence occurred in the Noksan national industrial complex from September 2002 to April 2007 by applying DInSAR and SBAS time series method using RADARSAT-1 and Envisat SAR datasets. As a result, it was calculated that ground subsidence developed at the velocity of about maximum 10 cm/yr and mean 6 cm/yr at the eastern center, west, western center and southern area contiguous on the coastline of the study area during the period from September 2002 to April 2007. In addition, the RADARSAT-1 average displacement map has been compared with the total displacement map observed by accurate magnetic probe extensometer during the period from 2001 to 2002. Since the time series displacement has shown a linear trend mostly, we consider that continuous monitoring should be needed until the ground subsidence of the study area has been stabilized.

Preliminary Study for Estimation of Nonlinear Constitutive Laws by using Back Analysis and Field Measurement (역해석 수법과 현장계측에 의한 비선형 구성법칙 결정에 관한 기초적인 연구)

  • Lee, Jae-Ho;Akutagawa, Shinichi;Kim, Young-Su;Sakurai, Shunsuke;Jin, Guang-Ri;Kim, Nag-Young
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.1278-1289
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    • 2008
  • Currently in increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method (NATM). Successful design, construction and maintenance of NATM tunnel in urban area demands prediction, control and monitoring of surface settlement, gradient and ground displacement with high accuracy. Use of measured displacement for parameter determination has been researched over the years, and one geotechnical engineering principle has been formed as back analysis. In this paper, back analysis of a ground deformational behavior involving nonlinear behavior is discussed. It is of primary importance to make reliable prediction of deformational behavior for shallow tunnels in soft ground. However, predictions made often prove to be incorrect due to complexity of constitutive law and other relevant factors. Back analysis therefore becomes more important, for it may be used to interpret measured displacement to derive nonlinear material characteristics. The paper shows some example in which a deformational mechanism is studied in the light of inhomogeneous distrubution of Young's module, from which a logic is derived to identify two different types of nonlinear constitutive relationships.

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Implementation of Algorithm for home network during a bio-sensor system activities (생체 센서 시스템을 동작하는 동안 홈 네트워크 시스템의 알고리즘 구현)

  • Kim, Jeong-Lae;Kwon, Young-Man
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.5
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    • pp.31-37
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    • 2010
  • This study was developed the home network system for the home stay care by bio-sensor system to translate the physical signal algorithm. The composition algorithm has five functions for a input function, frequency variable, displacement point input function, axial Variable, axial Sway Displacement to search a max and min point with adjustment of 0.01 unit in the reference level. There were checked physical condition of body balance to compounded a measurement such as a heart rate, temperature, weight. The algorithm of home network system can be used to support health care management system through health assistants in health care center and central health care system. It was expected to monitor a physical parameter for health management system.

Rock Mechanics-Major Projects and Research Topics in Korea (암반공학-우리나라에서의 과제와 연구주제)

  • Chung, So-Keul
    • Economic and Environmental Geology
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    • v.39 no.4 s.179
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    • pp.451-471
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    • 2006
  • Major projects and research topics in the field of rock mechanics are analyzed to obtain the following results: $\cdot$ Rock mechanics deals with the behavior of deformation, failure and displacement of the rock and rock mass on the basis of geological basics. Discontinuities in the rock mass are the most important parameters to control the behavior of rock mass around underground openings. $\cdot$ The objective of site investigation and testing is to determine the strength properties of the rock mass and the in situ stress regime. Specimens for laboratory and in situ tests are to be selected in order that the results of the tests give the representative properties oi the rock mass of the site in question. $\cdot$ The result of a numerical model would be better evaluated not quantitatively but qualitatively. The displacement behavior of the rock mass has to be monitored properly for the NATM (New Austrian Tunneling Method) principles. $\cdot$ The stability of rock slope is to be evaluated preferably by back analysis with strength parameters, such as cohesion and friction angle.