• Advanced Composite Materials
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• 제16권2호
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• pp.135-149
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• 2007

In the automobile industry, structural health monitoring of fiber reinforced polymer composite parts is a widespread need for maintenance before breakdown of the functional elements or a complete vehicle. High performance sensors are generally used in many of the structural health monitoring operations. Within this study, a carbon fiber sewing thread has been used as a low cost laminate failure sensing element. The experimentation plan was set up according to the electrical conductance and flexibility of carbon fiber threads, advantages of preforming operations, and sewing mechanisms. The influence of the single thread damages by changing the electrical resistance and monitoring the impact location by using carbon thread sensors has been performed. Innovative utilization of relatively cost-effective carbon threads for monitoring the delamination of metallic inserts from the basic composite laminate structure is a highlighting feature of this study.

• Earthquakes and Structures
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• 제8권3호
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• pp.541-553
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• 2015

Structural Health Monitoring (SHM) systems can provide valuable information regarding the safety of structures during and after ground motions which can be used by authorities to reduce post-earthquake hazards. Strain gages as a key element play an important role in the success of SHM systems. Reducing the number of required strain gages while keeping the efficiency of SHM system not only can reduce the cost of structural health monitoring but also avoids storage and process of uninformative data. In this study, a method based on performance based seismic design of structures is proposed for ideal placement of stain gages in structures. The robustness and efficiency of the proposed method is demonstrated through installation of strain gages on an Airport Traffic Control (ATC) Tower. The obtained results show that the number of required strain gages decrease significantly.

• 풍력에너지저널
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• 제9권4호
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• pp.16-23
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• 2018

A damage detection method for the tripod support structure of offshore wind turbines is presented for structural health monitoring. A finite element model of a prototype tripod support structure is established and the modal properties are calculated. The degree and location of the damage are estimated based on the neural network technique using the changes of natural frequencies and mode shape due to the damage. The stress distribution occurring in the support structure is obtained by a dynamic analysis for the wind turbine system to select the output data of the neural network. The natural frequencies and mode shapes for 36 possible damage scenarios were used for the input data of the learned neural network for damage assessment. The estimated damages agreed reasonably well with the accurate ones. The presented method could be effectively applied for damage detection and structural health monitoring of various types of support structures of offshore wind turbines.

• Structural Monitoring and Maintenance
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• 제10권4호
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• pp.339-360
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• 2023

In this paper, to assess the performance of a multi-span simply supported RC bridge, the dynamic characteristics of the bridge were measured and determined by structural health monitoring and resilient assessment via operational modal analysis as well as FE modeling. Supporting finite element (FE) models were created and analyzed according to the design drawings. This study used 2D plane monitoring of locations of hole in the infill wall and used 3D health monitoring and resilient assessment. From the results of 3Dsymmetric frame, if the frame is unsymmetrical, the used model can lead to the reduction in the internal forces. The recommendations from this study is from some discrepancies observed between 2D and 3D models, if possible 3D model should be used in analyzing the real frames.

• 전산구조공학
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• 제18권4호통권70호
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• pp.38-46
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• 2005

• Structural Engineering and Mechanics
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• 제87권5호
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• pp.451-460
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• 2023

Recently, the use of smartphones for structural health monitoring in civil engineering has drawn increasing attention due to their rapid development and popularization. In this study, the structural responses and dynamic characteristics of a 421-m-tall skyscraper during the landfall of Typhoon Muifa are monitored using an iPhone 13. The measured building acceleration responses are first corrected by the resampling technique since the sampling rate of smartphone-based measurement is unstable. Then, based on the corrected building acceleration, the wind-induced responses (i.e., along-wind and across-wind responses) are investigated and the serviceability performance of the skyscraper is assessed. Next, the amplitude-dependency and time-varying structural dynamic characteristics of the monitored supertall building during Typhoon Muifa are investigated by employing the random decrement technique and Bayesian spectral density approach. Moreover, the estimated results during Muifa are further compared with those of previous studies on the monitored building to discuss its long-term time-varying structural dynamic characteristics. The paper aims to demonstrate the applicability and effectiveness of smartphones for structural health monitoring of high-rise buildings.

• Safety and Health at Work
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• 제14권2호
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• pp.222-228
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• 2023

Background: This study aimed to explore relationships between job stress and psychological adaptation and how they related to interpersonal needs through mood states among female migrant manufacturing workers. Methods: A cross-sectional survey was conducted in 16 factories in Shenzhen, China. Sociodemographic, job stress, psychological adaptation and other psychological information of was collected. Structural equation modeling was performed to delineate the internal relationship between variables. Results: The hypothetical structural equation model exhibited acceptable model fit among female migrant manufacturing workers (χ² = 11.635, df = 2, χ²/df = 5.82, p = 0.003, RMSEA = 0.090, CFI = 0.972, SRMR = 0.020). Job stress was directly associated with mood states and interpersonal needs; Psychological adaptation was directly associated with mood states and indirectly associated with interpersonal needs; Bootstrapping tests demonstrated mediation effect of mood states in the way from psychological adaptation to interpersonal needs. Conclusion: Female migrant manufacturing workers who suffered stress from job and the process of psychological adaptation may have worse mood states and workers with worse mood states are more likely to develop unmet interpersonal needs, a proximal factor of suicidal ideation.

• 한국학교ㆍ지역보건교육학회지
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• 제13권3호
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• pp.13-31
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• 2012

Purpose: This study was on the structural analysis of the covariant amount in order to evaluate the suitability of the structural models which can explain and predict the mental health of children on the basis of Bronfenbrenner's ecological theory. Methods: A questionnaire was used to survey 269 children from dysfunctional families out of 5th and 6th grade students from 30 elementary schools in one city and 6 counties, which was analyzed by using PASW Statistics 18.0 and LISREL 8.7 programs. Results: The variable which had influence on the self-esteem was the social support. The variable which had influence on the positive reaction under stress was the stress. The variables which had influence on the negative reaction under stress were stress, and self esteem. The variables which had influence on the mental health were the self-esteem and the negative reaction under stress. The main variables to influence the mental health of children from dysfunctional families turned out to be the self-esteem and the negative reaction under stress to the mental health. Conclusion: Evaluating the suitability of the models, I presented the bases on the practical nursing business. They showed the right directions to the mental health care of children from dysfunctional families.

• 동서간호학연구지
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• 제24권2호
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• pp.101-109
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• 2018

Purpose: The purpose of this study was to construct and test a structural equation model of health behavior compliance among patients with percutaneous coronary intervention based on self-determination theory. Methods: A total of 227 participants who received follow-up care after percutaneous coronary intervention were recruited. A structured questionnaire was used to assess health providers' autonomous support, basic psychological needs, autonomous motivation, controlled motivation, type D personality, and health behavior compliance. Collected data were analyzed using SPSS 21.0 and AMOS 21.0 program. Results: The final hypothetical model showed a good fitness with data: GFI=.94, RMSEA=.07, CFI=.96, NFI=.92, TLI=.94. The results revealed that autonomous support of health care providers, basic psychological needs, and autonomous motivation, and D-type personality accounted for 51.8% of health behavior compliance. Conclusion: The findings of this study indicate that enhanced autonomous support of health care providers is essential to promote patients' basic psychological needs and autonomous motivation. This leads to maximized compliance to the health behaviors among patients who underwent percutaneous coronary intervention. We recommend that health care institutions establish various measures to foster the special environments in which health care providers can actively provide and utilize autonomous support for their patients.

• 한국해양공학회지
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• 제19권4호
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• pp.21-27
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• 2005

Large welded structures, including ships and offshore structures, are normally in operation under cyclic fatigue loadings. These structures include many geometric discontinuities, as well as material discontinuities due to weld joints. The fatigue strength at these hot spots is very important for the structural performance. In the past, various Non Destructive Evaluation (NDE) techniques have been developed to detect fatigue cracks and to estimate their location and size. However, an important limitation of most of the existing NDE methods is that they are off line; the normal operation of the structure has to be interrupted, and the device often has to be disassembled. This study explores the development of a structural health monitoring system, with a special interest in applying the technique to welded structural members in ship and offshore structures. In particular, the impedance based structural health monitoring technique that employs the coupling effect of piezoceramic (PZT) materials and structures is investigated.