• Structural Engineering and Mechanics
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• 제57권3호
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• pp.529-541
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• 2016

Under the interaction between dam body, dam foundation and external environment, the dam structural behavior presents the time-varying nonlinear characteristics. According to the prototypical observations, the correct identification on above nonlinear characteristics is very important for dam safety control. It is difficult to implement the description, analysis and diagnosis for dam structural behavior by use of any linear method. Based on the rescaled range analysis approach, the algorithm is proposed to identify and extract the fractal feature on observed dam structural behavior. The displacement behavior of one actual dam is taken as an example. The fractal long-range correlation for observed displacement behavior is analyzed and revealed. The feasibility and validity of the proposed method is verified. It is indicated that the mechanism evidence can be provided for the prediction and diagnosis of dam structural behavior by using the fractal identification method. The proposed approach has a high potential for other similar applications.

• Earthquakes and Structures
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• 제18권1호
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• pp.97-111
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• 2020

Cylindrical steel tanks are important components of industrial facilities. Their safety becomes a crucial issue since any failure may cause catastrophic consequences. The aim of the paper is to show the results of comprehensive FEM numerical investigation focused on the response of cylindrical steel tanks under mining tremors and moderate earthquakes. The effects of different levels of liquid filling, the influence of non-uniform seismic excitation as well as the aspects of diagnosis of structural damage have been investigated. The results of the modal analysis indicate that the level of liquid filling is really essential in the structural analysis leading to considerable changes in the shapes of vibration modes with a substantial reduction in the natural frequencies when the level of liquid increases. The results of seismic and paraseismic analysis indicate that the filling the tank with liquid leads to the substantial increase in the structural response underground motions. It has also been observed that the peak structural response values under mining tremors and moderate earthquakes can be comparable to each other. Moreover, the consideration of spatial effects related to seismic wave propagation leads to a considerable decrease in the structural response under non-uniform seismic excitation. Finally, the analysis of damage diagnosis in steel tanks shows that different types of damage may induce changes in the free vibration modes and values of natural frequencies.

• International Journal of Advanced Culture Technology
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• 제9권2호
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• pp.10-17
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• 2021

The core of the university policy pursued by the Moon Jae-in administration is to strengthen university competencies through the diagnosis of universities. To this end, the word structural reform evaluation is changed to strengthening the basic competencies of universities, and is trying to escape from the past reduction of pro-class capacity. Deputy Prime Minister Kim Sang-gon insisted, "We will improve the university structure evaluation, which is biased toward quantitative quota adjustment, with a diagnosis of basic university competency to support the autonomous development of the university." The Ministry of Education expressed its intention to strengthen the capacity of local universities by saying that it would also consider regional conditions in reducing the university quota due to the decrease in the school-age population so far. In the meantime, as the school-age population declined, the Ministry of Education promoted the reform of the university structure by dividing it into three cycles from 2014. This paper focuses on the problems of diagnosis of education reform and improvement measures, and tries to find out what is the desirable direction for education innovation. This paper studied the structural reform of universities following the decline of local universities. The policy alternatives in this paper are as follows. First, the contents of the government's push for university structural reform were analyzed. Second, we considered the problems of university structural reform. Third, they sought ways to develop local universities and enhance their competitiveness.

• 전산구조공학
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• 제23권5호
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• pp.34-41
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• 2010

• 한국구조물진단유지관리공학회지
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• 제18권1호
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• pp.27-36
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• 2014

• 전산구조공학
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• 제19권4호
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• pp.25-31
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• 2006

• 전산구조공학
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• 제32권4호
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• pp.11-16
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• 2019

• 한국정밀공학회지
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• 제27권6호
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• pp.64-74
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• 2010

This paper proposes a new TR-based baseline-free SHM technique in which the time-reversal (TR) property of the guided Lamb waves is utilized. The new TR-based SHM technique has two distinct features when compared with the other TR-based SHM techniques: (1) The backward TR process commonly conducted by the measurement is replaced by the computation-based process; (2) In place of the comparison method, the TOF information of the damage signal extracted from the reconstructed signal is used for the damage diagnosis in conjunction with the imaging method which enables us to represent the damage as an image. The proposed TR-based SHM technique is then validated through the damage diagnosis experiment for an aluminum plate with a damage at different locations.

• 한국방재안전학회논문집
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• 제15권4호
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• pp.21-30
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• 2022

우리나라는 1994년에 발생한 성수대교 붕괴사고를 계기로 ｢시설물의 안전 및 유지관리에 관한 특별법｣이 제정되면서 시설물의 안전점검 및 유지관리 분야에 많은 노력을 기울이고 있다. 이러한 시설물 중 건축물 다음으로 가장 많은 비중을 차지하는 교량은 현재 총33,165개소가 공용 중이며, 2, 3종 교량의 경우 28,150개소로 전체 비중의 약 85%를 차지하고 있다. 하지만 교량의 대부분을 차지하고 있는 2, 3종 교량은 상대적으로 중요도가 높은 1종 교량에 비해 점검진단 등에 관한 유지관리 현황이 미흡한 실정이다. 이러한 이유는 교량의 점검진단 수행 시 점검진단 수행자의 주관적인 판단 및 기록, 체계적으로 수립되지 못한 점검진단 보고서 양식 등에서 나타난다. 따라서 본 연구에서는 기존 점검진단 보고서의 문제점을 수정 및 보완하여 체계적이고 지속적으로 활용 가능한 점검진단 보고서의 개선(안)을 도출하고자 한다.

• 한국구조물진단유지관리공학회 논문집
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• 제11권1호
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• pp.113-120
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• 2007

새로운 재료의 적용 실험을 통하여, 탄소섬유 분말 혼입 모르타르 복합 구조체의 파괴예측 자가진단 적용 특성에 대해 검토하였다. 본 연구에서는 자가진단 성능을 부여하기 위해 코크스와 탄소섬유분말(미분쇄 탄소섬유)이 혼입된 전도성 모르타르의 개발 및 자가진단 재료로서의 사용이 제안되었다. 각 하중재하단계에서의 균열발생 전후의 전기저항값과 AE특성치의 변화특성 시험을 통해, 이들 각 인자의 상호 연관성을 검토하였다. 그 결과, 코크스와 탄소섬유분말(미분쇄 탄소섬유)을 사용하여 새롭게 제안된 복합재료는 모르타르 시험체의 파괴 자가진단에 사용이 가능함을 알 수 있었다.