• 한국해양공학회지
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• 제14권1호
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• pp.80-87
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• 2000

Despite many combined research efforts outstanding needs exist to develop robust safety-estimation methods for large complex structures. This paper presents a practical damage identification scheme which can be applied to truss structures using only limited modal responses. firstly a theory of pattern recognition (PR) is described. Secondly existing damage-detection algorithms are outlined and a newly-derived algorithms for truss structures. Finally the feasibility of the proposed scheme is evaluated using numerical examples of plane truss structures.

• Structural Monitoring and Maintenance
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• 제6권3호
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• pp.173-190
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• 2019

Steel-confined reinforced concrete (SCRC) columns feature highly complex and invisible mechanisms that make damage evaluation and pattern recognition difficult. In the present article, the prevailing acoustic emission (AE) technique was applied to monitor and evaluate the damage process of steel-confined RC columns in a quasi-static test. AE energy-based indicators, such as index of damage and relax ratio, were proposed to trace the damage progress and quantitatively evaluate the damage state. The fuzzy C-means algorithm successfully discriminated the AE data of different patterns, validity analysis guaranteed cluster accuracy, and principal component analysis simplified the datasets. A detailed statistical investigation on typical AE features was conducted to relate the clustered AE signals to micro mechanisms and the observed damage patterns, and differences between steel-confined and unconfined RC columns were compared and illustrated.

• International Journal of Railway
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• 제7권4호
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• pp.94-99
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• 2014

Urban railway systems are located under populated areas and are mostly constructed for underground structures which demand high standards of structural safety. However, the damage progression of underground structures is hard to evaluate and damaged underground structures may not effectively stand against successive earthquakes. This study attempts to examine initial damage-stage and to access structural damage condition of the ground structures using Earthquake Damage Monitoring (EDM) system. For actual underground structure, vulnerable damaged member of Ulchiro-3ga station is chosen by finite element analysis using applied artificial earthquake load, and then damage pattern and history of damaged members is obtained from measured acceleration data introduced unsupervised learning recognition. The result showed damage index obtained by damage scenario establishment using acceleration response of selected vulnerable members is useful. Initial damage state is detected for selected vulnerable member according to established damage scenario. Stiffness degrading ratio is increasing whereas the value of reliability interval is decreasing.

• Smart Structures and Systems
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• 제7권2호
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• pp.117-132
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• 2011

This paper is aimed at presenting two methods on the basis of pattern search and genetic algorithms to detect and estimate damage in plates using the modal data of a damaged plate. The proposed methods determine the damages of plate structures using optimization of an objective function by pattern search and genetic algorithms. These methods have been applied to two numerical examples, namely four-fixed supported and cantilever plates with and without noise in the modal data and containing one or several damages. The obtained results clearly reveal that the proposed methods can be viewed as a powerful and reliable method for structural damage detection in plates using the modal data.

• 동의생리병리학회지
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• 제27권1호
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• pp.1-10
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• 2013

We can understand "Shanghanlun(傷寒論)" and "Wenbingtiaobian(溫病條辨)" which are major books on externally contracted diseases well by making a comparative study of their similarities and differences. After studying etiological causes and characteristics of disease, disease pattern, syndrome differentiation, transmutation rules, following conclusions are derived. While cold is an etiological cause of Cold damage and harms Yang qi, heat is an etiological cause of Warm disease and harms Yin qi. Cold damage and Warm disease have something in common in the respect of damage to fluid and humor and Yang qi. Exuberant heat symptom of Yang brightness disease and lesser yin heat transformation pattern have similar damage to fluid and humor as Warm disease does. Warm disease can reach qi collapse syndrome through damage to Yang qi following fluid and humor damage. In the respect of water qi, as Cold damage makes water-dampness retain easily due to cold congealing, dampness-draining diuretic medicinal and warm yang medicinal are used together. As warm disease damages fluid and humor, yin-tonifying medicinal is used and dampness-draining diuretic medicinal can be used in the case of Warm disease with dampness. In the respect of disease pattern, cold syndromes arise mostly by Cold damage except heat syndrome of grater yang disease, chest bind syndrome, stuffiness syndrome, reverting yin disease and yang brightness disease. Warm disease is classified as pure heat syndrome and heat syndrome with bowel excess, damage to yin, qi collapse or damage to blood.

• Coupled systems mechanics
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• 제4권1호
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• pp.19-36
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• 2015

Modelling and analysis of a brick masonry building involves uncertainties like modelling assumptions and properties of local material. Therefore, it is necessary to perform a calibration to evaluate the dynamic properties of the structure. The response of the finite element model is improved by predicting the parameter by performing linear dynamic analysis on experimental data by comparing the acceleration. Further, a nonlinear dynamic analysis was also performed comparing the roof acceleration and damage pattern of the structure obtained analytically with the test findings. The roof accelerations obtained analytically were in good agreement with experimental roof accelerations. The damage patterns observed analytically after every shock were almost similar to that of experimental observations. Damage pattern with amplification in roof acceleration exhibit the potentiality of earthquake resistant measures in brick masonry models.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.483-492
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• 2004

This paper presents an efficient algorithm for the estimation of damage location and severity in bridge structures using Probabilistic Neural Network (PNN). Generally, the Back Propagation Neural Network (BPNN)-based damage detection methods need a lot of training patterns for neural network learning process and the optimum architecture of a BPNN is selected by trial and error. In this paper, the PNN instead of the conventional BPNN is used as a pattern classifier. The modal properties of damaged structure are somewhat different from those of undamaged one. The basic idea of proposed algorithm is that the PNN classifies a test pattern which consists of the modal characteristics from damaged structure, how close it is to each training pattern which is composed of the modal characteristics from various structural damage cases. In this algorithm, two PNNs are sequentially used. The first PNN estimates the damage location using mode shape and the results of the first PNN are put into the second PNN for the damage severity estimation using natural frequency. The proposed damage assessment algorithm using the PNN is applied to a cable-stayed bridge to verify its applicability.

• 한국구조물진단유지관리공학회 논문집
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• 제6권4호
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• pp.169-179
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• 2002

This paper presents an efficient algorithm for the estimation of damage location and severity in structure using Probabilistic Neural Network (PNN). Artificial neural network has been being used for damage assessment by many researchers, but there are still some barriers that must be overcome to improve its accuracy and efficiency. The major problems with the conventional neural network are the necessity of many training data for neural network learning and ambiguity in the relation of neural network architecture with convergence of solution. In this paper, PNN is used as a pattern classifier to overcome those problems in the conventional neural network. The basic idea of damage assessment algorithm proposed in this paper is that modal characteristics from a damaged structure are compared with the training patterns which represent the damage in specific element to determine how close it is to training patterns in terms of the probability from PNN. The training pattern that gives a maximum probability implies that the element used in producing the training pattern is considered as a damaged one. The proposed damage assessment algorithm using PNN is applied to a 2-span continuous beam model structure to verify the algorithm.

• 한국의사학회지
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• 제27권2호
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• pp.135-143
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• 2014

Human body fluid and humor include not only sweat, joint fluid but also every fluids, for example, blood, essence, kidney essence and marrow. Historically, in the oriental medicine, there are a lot of efforts in order to preserve fluid and humor. In "Treatise on Cold Damage and Miscellaneous Disease (傷寒雜病論)", when treating cold damage, preservation of fluid and humor is put first. I tried to find out the relation about fluid and humor and pain treatment in "Treatise on Cold Damage and Miscellaneous Disease". So, I investigated sentences related to pains in "Treatise on Cold Damage and Miscellaneous Disease" "greater yang disease part" and commentaries of several chinese medical doctors. And I divide pain treatments into four categories. (fluid and humor sufficiency-exterior pattern, fluid and humor sufficiency-interior pattern, fluid and humor deficiency-exterior pattern, fluid and humor deficiency-interior pattern) At first, when treating pains of cold damage, there are many considerations about deficiency and sufficiency of fluid and humor through pulse condition and symptoms. Second, in pain-cases of fluid and humor sufficiency, purge methods is chosen. And in pain-cases of fluid and humor deficiency, tonifying methods is chosen. Finally, one of the main objects of "Treatise on Cold Damage and Miscellaneous Disease" is preservation and supply of fluid and humor.

• 한국산학기술학회논문지
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• 제18권11호
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• pp.810-816
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• 2017

본 연구는 사장교 케이블의 주요 부재로 쓰이는 MS(Multi-strand) 타입 7연선의 손상 패턴과 성능수준과의 관계를 파악하기 위해 시도되었다. 사장교 케이블은 준공후 지속적으로 손상이 발생하며 부식 등이 주요 손상원인이다. 이에 따른 손상에 따라 성능저하가 발생하지만 구조적인 특성상 케이블 내부의 손상 패턴을 점검하기 어려우며, 이에 따른 성능저하 수준을 정량적으로 평가하기 어려운 실정이다. 본 연구에서는 강연선의 손상 패턴과 성능수준과의 관계를 도출하기 위해 실내실험 및 FEA(Finite element analysis) 해석을 통하여 결과를 비교 분석하였다. 그리고 7연선의 손상을 모사하기 위해 기계적 정밀가공으로 인위적인 손상을 인가하여 성능평가를 수행하였다. 분석 결과 강연선의 손상 크기와 관계없이 손상이 발생한 직후 급격한 구조성능 저하가 발생하며, 강연선 성능수준 평가를 위한 변수로 손상량 이외에 손상 형태가 고려돼야 함을 실험적 및 해석적으로 도출하였다. 향후 본 연구에서 구축하고자 하는 손상 패턴 및 손상량에 따른 DB를 구축하여 사장교 케이블의 안전 관리에 활용될 수 있을 것으로 사료된다.