• Nuclear Engineering and Technology
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• 제51권1호
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• pp.170-175
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• 2019

Displacement cross-sections for an advanced assessment of radiation damage rates were obtained for a number of materials using the arc-dpa model at neutron incident energies from $10^{-5}eV$ to 10 GeV. Evaluated data files, CEM03 and ECIS codes, and an approximate approach were applied for the calculation of recoil energy distributions in neutron induced reactions. Three sets of displacement cross-sections based on the use of low-energy data from JEFF-3.3, ENDF/B-VIII.0, and JENDL-4.0u were prepared. Files contain also cross-sections calculated using the standard NRT model. Special efforts were made to estimate the uncertainty of obtained displacement cross-sections.

• 한국지반환경공학회 논문집
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• 제20권6호
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• pp.15-22
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• 2019

본 연구에서는 현장조사, 실내시험 및 문헌자료를 기초로 지진 시 산사태 발생 위험지 예측 모델인 Newmark displacement model을 이용하여 위험지를 예측하였다. Newmark displacement model은 주로 지진의 정보와 해당 지역의 사면의 정보를 통해 산정되며, 사면의 안전율은 산지 토사재해 예측 프로그램인 LSMAP의 결과를 활용하였다. 연구대상 지역으로 과거 산사태가 발생한 부산의 백양산 일대를 선정하였다. 산사태 발생 해석 결과 Newmark displacement model을 활용한 지진 시 산사태 위험지 예측이 지진 계수가 미적용된 LSMAP의 산사태 위험지 예측보다 약 1.15배 넓은 지역을 위험지역으로 예측하는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.75-90
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• 2013

In order to identify damage of highway bridges rapidly, a method for damage identification using dynamic response of bridge induced by moving vehicle and static test data is proposed. To locate damage of the structure, displacement energy damage index defined from the energy of the displacement response time history is adopted as the indicator. The displacement response time histories of bridge structure are obtained from simulation of vehicle-bridge coupled vibration analysis. The vehicle model is considered as a four-degree-of-freedom system, and the vibration equations of the vehicle model are deduced based on the D'Alembert principle. Finite element method is used to discretize bridge and finite element model is set up. According to the condition of displacement and force compatibility between vehicle and bridge, the vibration equations of the vehicle and bridge models are coupled. A Newmark-${\beta}$ algorithm based professional procedure VBAP is developed in MATLAB, and used to analyze the vehicle-bridge system coupled vibration. After damage is located by employing the displacement energy damage index, the damage extent is estimated through the least-square-method based model updating using static test data. At last, taking one simply supported bridge as an illustrative example, some damage scenarios are identified using the proposed damage identification methodology. The results indicate that the proposed method is efficient for damage localization and damage extent estimation.

• Communications for Statistical Applications and Methods
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• 제11권1호
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• pp.189-196
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• 2004

The sensitivity of the multivariate Box-Cox transformation model to simultaneous perturbations of all the data based on the likelihood displacement is studied in order to detect outliers. An example is given for illustration.

• Smart Structures and Systems
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• 제3권3호
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• pp.373-384
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• 2007

For structural health monitoring (SHM) of civil infrastructures, displacement is a good descriptor of the structural behavior under all the potential disturbances. However, it is not easy to measure displacement of civil infrastructures, since the conventional sensors need a reference point, and inaccessibility to the reference point is sometimes caused by the geographic conditions, such as a highway or river under a bridge, which makes installation of measuring devices time-consuming and costly, if not impossible. To resolve this issue, a visionbased real-time displacement measurement system using digital image processing techniques is developed. The effectiveness of the proposed system was verified by comparing the load carrying capacities of a steel-plate girder bridge obtained from the conventional sensor and the present system. Further, to simultaneously measure multiple points, a synchronized vision-based system is developed using master/slave system with wireless data communication. For the purpose of verification, the measured displacement by a synchronized vision-based system was compared with the data measured by conventional contact-type sensors, linear variable differential transformers (LVDT) from a laboratory test.

• 한국소음진동공학회논문집
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• 제21권2호
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• pp.112-119
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• 2011

This paper is concerned with the measurement of static and dynamic displacement by image processing(IP) and study for prediction method of velocity and acceleration. To measure the displacement visually, the measurement system consists of a telephoto zoom camera, CCD(charge coupled device) image device and a computer. The specific target on the white board is used to calculate the displacement of the structure. The captured image is then converted into a pixel-based data and then analyzed numerically. The limitation of the system depends on the image capturing speed and the pixel-size of image. In this paper, we developed for the displacement measurement using the image processing method. The proposed method enables us to measure the vibration displacement, velocity and acceleration directly without any contact. The current resolution for the displacement measurement can be seen from the results.

• Smart Structures and Systems
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• 제15권3호
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• pp.881-896
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• 2015

The authors' research group has developed a noncontact type of sensors which directly measure the inter-story drift displacements of a building during a seismic event. Soon after that event, such seismically-induced drift displacement data would provide structural engineers with useful information to judge how the stories have been damaged. This paper presents a scheme of estimating the story cumulative plastic deformation ratios based on such measured drift displacement information toward the building safety monitoring. The presented scheme requires the data of story drift displacements and the ground motion acceleration. The involved calculations are rather simple without any detailed information on structural elements required: the story hysteresis loops are first estimated and then the cumulative plastic deformation ratio of each story is evaluated from the estimated hysteresis. The effectiveness of the scheme is demonstrated by utilizing the data of full-scale building model experiment performed at E-defense and conducting numerical simulations.

• 한국해안·해양공학회논문집
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• 제20권4호
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• pp.413-420
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• 2008

파랑하중은 연약지반을 굴착 치환시킨 후에 축조된 사석경사식 방파제의 안정에 직접적인 영향을 주는 요소이다. 특히 일부 침하를 허용하는 굴착치환 사석경사 방파제에서 침하를 유발하는 주요인으로 지목되었으나, 설계 시 파랑하중에 의한 방파제의 침하에 대한 영향을 검토하여 반영하는 사례가 전무한 상태이다. 따라서 본 연구에서는 파랑하중에 의한 방파제 침하의 영향을 설계에 직접 반영할 수 있도록 수치모형실험을 실시하여 방파제 침하량을 계산한 후 현장계측자료와 비교하였다. 계산값과 실측값은 양호한 일치를 보이는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 봄 학술회 논문집
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• pp.27-32
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• 1993

In tunnelling by NATM convergence data are most Importantly to ascertain the safety of tunnel. Therefore, a reliable method is required that can predict ultimate displacements by using earler displacement data. Displacement forecasting method is classified into statistical method and functional regression method. Convergence data measured in Seoul subway 5~45 site during '92.5 ~ '92.12 were analyzed by above said two methods. The analysis results of convergence data show that the functional regression method is more relieable in completely weathered rock, but the statistical method in slightly wearhred rock.

• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.355-363
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• 2023

노후 교량의 안전성을 평가하는 방법에 있어서 동특성과 처짐은 구조계의 강성과 직접 연관이 있으며, 처짐의 경우에는 교량 사용자가 직접 감지할 수 있는 물리량으로 가장 중요한 인자이다. 하지만 교량의 처짐을 측정하기 위해서는 교량의 하부에 처짐계를 설치하고 교통 차단 및 재하시험을 실시해야 하는 번거로움이 있어 교량의 환경에 따라서 비용이 증가하거나 측정이 불가능한 문제들이 발생하고 있다. 본 연구에서는 처짐계의 설치 없이 가속도계만을 이용하고 재하시험 없이 상시 진동을 이용하여 교량의 처짐을 측정하는 방법을 제안하였다. 상시 진동을 이용한 교량 동특성 및 처짐 분석을 위해 단순한 연산으로 빠른 분석이 가능하다고 알려진 TDD 기법을 이용하여 교량의 모드형상과 고유진동수를 추출하였으며, 유연도 분석을 통하여 교량의 단위하중 처짐을 분석하여 정적 처짐까지 산정하였다. 본 제안 기술의 검증을 위해 공용중 교량인 C대교(사장교)에 적용하여 모드형상, 고유진동수, 정적 처짐 분석을 수행하였으며 재하시험 실측값과 구조해석 자료와 비교하였다. 그 결과 모드형상 및 고유진동수는 0.42~1.13 %, 중앙경간에서의 최대 처짐은 3.58 %의 오차율을 확인하였다. 따라서 제안기술은 처짐계의 설치가 어려워 실측이 불가능한 교량의 처짐을 추정하여 설계값 및 해석값 대비 처짐 발생량 비교로 교량의 안전성을 간접적으로 파악할 수 있는 근거 자료로 활용 가능할 것으로 사료된다.