• 한국지반환경공학회 논문집
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• 제13권5호
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• pp.25-33
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• 2012

본 연구에서는 흙막이 가시설 공법중 지반의 변위를 억제하고, 토공사 및 구조물 공사의 시공성을 크게 개선한 IPS 흙막이 가시설 공법을 시공한 현장의 계측자료를 바탕으로, 탄소성보법 수치해석 프로그램(EXCAV/W)을 이용하여 수치해석을 실시하였다. 그 결과, 선행하중을 가한 해석치가 평균 13.2% 감소하였으며, 또한 일반적인 해석치보다 현장 계측치는 평균 26.7% 감소하는 것으로 나타났다. 따라서 IPS 흙막이 가시설 공법은 기존 버팀보 공법에 흙막이벽의 수평변위에 대한 안전성을 확보하고 있음을 알 수 있다. 또한 IPS 흙막이 가시설 공법을 이용한 선행하중 효과를 통해 수평변위가 감소하는 것을 확인할 수 있다.

• 한국소음진동공학회논문집
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• 제24권6호
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• pp.476-482
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• 2014

The stress analysis of the pipeline is required in any kind of plant for its safe operation. For this, the displacement vibration data measured at many locations of the pipeline should be provided. In reality, the installation of the non-contact type displacement sensors such as laser displacement sensors or eddy current type proximity sensors in a narrow and confined region in the vicinity of the pipeline is almost impracticable. In this work, the general purpose piezo-ceramic accelerometers were attached on the measuring points on the pipeline and the acceleration vibration signal was acquired. The measured acceleration signal was low pass filtered and then downsampled. The resulting acceleration signal was transformed into both the time-domain and frequency-domain displacement signal utilizing the fast Fourier transform techniques. All the procedures are presented in detail. It is demonstrated that the measurement of the pipeline acceleration by using contact type accelerometers can be made for the purpose of providing the required displacement data for the stress analysis of the pipeline.

• Smart Structures and Systems
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• 제15권3호
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• pp.645-663
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• 2015

Recently, an indirect displacement estimation method using data fusion of acceleration and strain (i.e., acceleration-strain-based method) has been developed. Though the method showed good performance on beam-like structures, it has inherent limitation in applying to more general types of bridges that may have complex shapes, because it uses assumed analytical (sinusoidal) mode shapes to map the measured strain into displacement. This paper proposes an improved displacement estimation method that can be applied to more general types of bridges by building the mapping using the finite element model of the structure rather than using the assumed sinusoidal mode shapes. The performance of the proposed method is evaluated by numerical simulations on a deck arch bridge model and a three-span truss bridge model whose mode shapes are difficult to express as analytical functions. The displacements are estimated by acceleration-based method, strain-based method, acceleration-strain-based method, and the improved method. Then the results are compared with the exact displacement. An experimental validation is also carried out on a prestressed concrete girder bridge. The proposed method is found to provide the best estimate for dynamic displacements in the comparison, showing good agreement with the measurements as well.

• 한국재난정보학회 논문집
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• 제13권3호
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• pp.286-295
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• 2017

본 연구는 경사계에 의한 지중수평변위 계측값을 중심으로 수치해석에 적용하기 위한 지반 반력계수를 다양한 이론 및 경험식으로 산출하여 비교하였다. 산정된 지반반력계수의 변화에 따라 벽체 최상단에서는 벽체변위의 최소값과 최대값의 차이가 6.80배로 크게 났으나, 최대 변위점에서는 차이는 거의 없는 1.06배로 나타나 지반반력계수의 증분에 비해 변위의 차이는 작으며 전체적으로 비슷한 값을 나타내었다. 또한 최대변위 발생점에서의 변위를 수치해석한 결과와 계측치로 비교한 결과 변위형상은 비슷하게 나타났다.

• 한국전산구조공학회논문집
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• 제29권4호
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• pp.301-308
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• 2016

본 연구에서는 마커없이 구조물의 변위를 측정할 수 있는 영상기반 변위계측 시스템(NVDMS)을 제안한다. 기존의 방식과 제안하는 NVDMS는 크게 두 가지의 차이점이 있다. 첫째, NVDMS는 마커를 사용하지 않고 구조물의 특징점의 픽셀좌표 변화를 추출한다. 둘째, 특징점의 픽셀좌표를 물리좌표로 변환하는 scaling factor는 기존 방식에선 마커의 크기로부터 계산되는 반면, NVDMS에서는 카메라와 구조물사이의 거리, 각도, 초점거리로 계산된다. 3층 축소모형의 자유진동 실험에서 제안한 NVDMS로부터 얻은 변위데이터의 신뢰도를 분석하기 위해 LDS로부터 얻은 변위데이터의 비교를 하였으며, 얻어진 변위데이터를 이용하여 동특성을 분석하였다. 분석결과 NVDMS는 마커없이 구조물의 동적변위를 정밀하게 측정가능할 뿐만 아니라 얻어진 변위데이터로부터 추출한 동특성의 신뢰도 또한 높았다.

• Geomechanics and Engineering
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• 제33권1호
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• pp.77-89
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• 2023

This study aims to establish the correlations between variables related to a slope during rainfall and factor of safety (FOS) and displacement using a coupling analysis method that is designed to consider both in rainfall conditions. With the recent development of measurement technologies, the approach of using the measurement data in the field has become easier. Particularly, they have been obtained in tests to determine the real-time safety and movement of a slope; however, a specific method has not been finalized. In addition, collected measurement data for recognizing the FOS and displacement in real-time with a specific relevance is difficult, and risks of uncertainty, such as in soil parameters and time, exist. In this study, the correlations between various slope-related variables (i.e., rainfall intensity, rainfall duration, angle of the slope, and mechanical properties including strength parameters of selected three types of soil; loamy sand, silt loam, sand) and the FOS and displacement are analyzed in order of seepage analysis, slope stability analysis and slope displacement analysis. Moreover, the methodology of coupling analysis is verified and a fundamental understanding of the factors that need to be considered in real-time observations is gained. The results show that the contributions of the abovementioned variables vary according to the soil type. Thus, the tendency of the displacement also differs by the soil type and variables but not same tendency with FOS. The friction angle and cohesion are negative while the rainfall duration and rainfall intensity are positive with the displacement. This suggests that understanding their correlations is necessary to determine the safety of a slope in real-time using displacement data. Additionally, databases considering rainfall conditions and a wide range of soil characteristics, including hydraulic and mechanical parameters, should be accumulated.

• 지질공학
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• 제33권4호
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• pp.639-655
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• 2023

최근 지하공간에 대한 수요가 많아지면서 대심도 굴착으로 흙막이 벽체가 활용되고 있다. 흙막이 벽체는 변위에 취약한 구조물로써 국토교통부에서 제시한 관리기준으로 계측관리를 수행하고 있으나 계측관리를 통한 대비는 후처리에 가깝다고 할 수 있다. 따라서 본 연구에서는 머신러닝을 이용한 그라운드 앵커가 설치된 흙막이 벽체의 수평변위 예측뿐만 아니라 머신러닝으로 계측데이터를 학습하는 과정에서 데이터 스케일링과 분할 방법에 따른 예측모델의 영향을 분석하였다. 이 연구의 분석결과에 따르면 사용자 지정분할방법이 적합하지 않은 경우도 있었으나 일정 조건하에서 데이터 학습 및 출력에 가장 우수한 성능을 나타냈다. 데이터 스케일링은 앵커의 인장력, 수압을 표준화하였을 때 오차 1 이내, R-Squared 값이 0.77로 우수한 성능을 나타냈으며 스케일링을 적용하지 않은 모델 대비 음의 변위를 예측하는 결과를 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.94.3-94
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• 2001

A sensor system was developed to measure displacement of civil structure at a long distance. A He-Ne Laser tube and photodiodes ware used for non-contact measurement. This system allows real time vibration displacement measurement of bridges. The measured displacement data is displayed on computer monitor graphically and also in digit. The accuracy of the displacement measurement shows 2mm in vertical vibration. It shows remote inspection of the vibration of long bridges and buildings.

• Structural Monitoring and Maintenance
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• 제5권1호
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• pp.129-150
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• 2018

This paper presents the structural performance monitoring of an urban footbridge located in Hangzhou, China. The structural health monitoring (SHM) system is designed and implemented for the footbridge to monitor the structural responses of the footbridge and to ensure the structural safety during the period of operation. The monitoring data of stress and displacement measured by the fiber Bragg grating (FBG)-based sensors installed at the critical locations are used to analyze and assess the operation performance of the footbridge. A linear regression method is applied to separate the temperature effect from the stress monitoring data measured by the FBG-based strain sensors. In addition, the static vertical displacement of the footbridge measured by the FBG-based hydrostatic level gauges are presented and compared with the dynamic displacement remotely measured by a machine vision-based measurement system. Based on the examination of the monitored stress and displacement data, the structural safety evaluation is executed in combination with the defined condition index.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.107-108
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• 2011

A methodology to measure 3-dimensional vibrational displacement of a structure by digital photogrammetry is proposed in this paper. Stereo digital images of a vibrating structure were obtained by two non-metric cameras. Then by applying the collinearity condition to the images, the 3-d displacement time history data of a point or many points can be calculated by the present methodology. Experimental work was performed to measure the displacement time history for a cantilever beam excited by a piezoelectric patch, in which the in-depth displacement data obtained by the proposed method well matched the laser sensor data.