• Journal of Ocean Engineering and Technology
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• v.26 no.1
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• pp.27-33
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• 2012

This paper presents the effect of temperature on the impedance-based damage monitoring of steel-bolt connections using wireless impedance sensor nodes. In order to achieve the objective, the following approaches are implemented. First, a temperature-compensated damage monitoring scheme that includes a temperature compensation model and damage detection method is described. The temperature compensation model is designed by analyzing the linear regressions between the temperatures and impedance signatures. The correlation coefficient of the impedance signatures is selected as the damage index to monitor the damage occurrence in the target structures. Second, a wireless impedance sensor node is described for the design of the hardware components and embedded software. Finally, the performance of the temperature-compensated impedance-based damage monitoring scheme is evaluated for detecting a loose bolt in the steel-bolt connections on a lab-scale steel girder under various temperatures.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.4
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• pp.367-374
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• 2005

Recently, forest damage has occurred often and made big issues. Among them, the damage by forest fire is not only damage of itself but also being connected with secondary damage like a flood. This is the fact that a forest fire is caused rather artificially by people than nature. In this study, we try to investigate damage of a forest fire through spectral reflectance of a plant community surveyed using a near infrared CCD camera and a SPM (Spectral Radiometer) as advanced work to use satellite image data. That is, damage of a forest fire by the naked eye observation was divided into the No damage, the light damage, the serious damage and we estimated activity of forest and grasped revival possibility of forest. Through correlation analysis between the spectral reflectance by SPM and the near infrared CCD camera, we could get high correlation in the No damage and light damage. Therefore, when we surveyed damage of a forest fire, we could grasp damage, that is hardly observed by the naked eye by, using jointly the spectral radiometer and the near infrared CCD camera.

• Coupled systems mechanics
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• v.12 no.5
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• pp.445-459
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• 2023

In this study, a cyclic tensile test on a notched butterfly specimen made of woven glass fiber composite was performed on a modified Arcan fixture. During the mechanical test, the sample was monitored with a hybrid stereoscopic system comprised of two visible lights and one infrared camera. The visible light cameras were employed for kinematic measurements using a finite-element-based multiview correlation technique. A semi-hybrid correlation approach was followed, providing Lagrangian temperature fields of the Region of Interest. Due to the complex composite architecture and specimen shape, localized shearing was observed during the tensile loading. Furthermore, asymmetrical damage developed around the notches as revealed by localized strains and thermal hot spots.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.81-89
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• 2012

This study propose the vibration-based damage monitoring scheme for steel girder bolt-connection member by using wireless acceleration sensor node. In order to achieve the objective, the following approaches are implemented. Firstly, wireless acceleration sensor node is described on the design of hardware components and embedded operation software. Secondly, the vibration-based damage monitoring scheme of the steel girder bolt-connection member is described. The damage monitoring scheme performed global damage occurrence alarming and damage localization estimation by the acceleration response feature analysis. The global damage alarming is applied to the correlation coefficient of power spectral density. The damage localization estimation is applied to the frequency-based damage detection technique and the mode-shape-based damage detection technique. Finally, the performance of the vibration-based damage monitoring scheme is evaluated for detecting the bolt-connection member damage on a lab-scale steel girder.

• Earthquakes and Structures
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• v.9 no.5
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• pp.1091-1114
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• 2015

The adequacy of a number of advanced earthquake Intensity Measures (IMs) to predict the structural damage of earthquake resistant 3D R/C buildings is investigated in the present paper. To achieve this purpose three symmetric in plan and three asymmetric 5-storey R/C buildings are analyzed by nonlinear time history analysis using 74 bidirectional earthquake records. The two horizontal accelerograms of each ground motion are applied along the structural axes of the buildings and the structural damage is expressed in terms of the maximum and average interstorey drift as well as the overall structural damage index. For each individual pair of accelerograms the values of the aforementioned seismic damage measures are determined. Then, they are correlated with several strong motion scalar IMs that take into account both earthquake and structural characteristics. The research identified certain IMs which exhibit strong correlation with the seismic damage measures of the studied buildings. However, the degree of correlation between IMs and the seismic damage depends on the damage measure adopted. Furthermore, it is confirmed that the widely used spectral acceleration at the fundamental period of the structure is a relatively good IM for medium rise R/C buildings that possess small structural eccentricity.

• Structural Engineering and Mechanics
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• v.72 no.1
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• pp.83-97
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• 2019

In this research, the vulnerability of some reinforced concrete frames with different stories are studied based on the Park-Ang Damage Index. The damages of the frames are investigated under various earthquakes with nonlinear dynamic analysis in IDARC software. By examining the most important characteristics of earthquake parameters, the damage index and vulnerability of these frames are investigated in this software. The intensity of Erias, velocity spectral intensity (VSI) and peak ground velocity (PGV) had the highest correlation, and root mean square of displacement ($D_{rms}$) had the lowest correlation coefficient among the parameters. Then, the particle swarm optimization (PSO) algorithm was used, and the sinusoidal waves were equivalent to the used earthquakes according to the most influential parameters above. The damage index equivalent to these waves is estimated using nonlinear dynamics analysis. The comparison between the damages caused by earthquakes and equivalent sinusoidal waves is done too. The generations of sinusoidal waves equivalent to different earthquakes are generalized in some reinforced concrete frames. The equivalent sinusoidal wave method was exact enough because the greatest difference between the results of the main and artificial accelerator damage index was about 5 percent. Also sinusoidal waves were more consistent with the damage indices of the structures compared to the earthquake parameters.

• Anxiety and mood
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• v.8 no.1
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• pp.31-40
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• 2012

Objective : The purpose of this study was to analyze the correlation between symptom severity and neurocognitive factors in traumatic head injury patients. In addition, the effect of frontal lobe damage on these parameters was examined. Methods : We selected 18 patients who had brain damage for the moderate to severe traumatic brain injury (MSTBI) group, and 17 patients who met the diagnostic criteria for post-traumatic stress disorder (PTSD) without the finding of brain damage for the comparison group. For the evaluation of neurocognitive function, K-WAIS, Rey-Kim Memory Test, K-FENT, WCST, and MMPI-2 were used. Results : The results of the comparison (using the malingering scale) revealed that the values of PDS and PK, which express the severity of symptoms, and the values of the validity scale F, F (B), and F (P) were significantly higher in the overly-expressed group. F (B) in overly-expressed group and PK, Pt, and Sc in the properly-expressed group had significant correlation with the severity of symptoms. F (B), S, and Stroop error inhibition in PTSD, and PK, Pt, Sc, and MQ in MSTBI had significant correlation with the severity of symptoms. The results of the comparison based on the finding of frontal lobe damage revealed that PDS, EIQ, and MQ ware significantly higher in the group without brain damage. Conclusions : It was revealed that each neurocognitive factor was correlated with the severity of symptoms. There was a decrease in complaints or symptoms reported by the frontal lobe injury group, and this is believed to be due to degenerative change in the personality and emotional functioning of these patients following frontal lobe damage.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.1
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• pp.15-25
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• 2020

Purpose : Sexual harassment cases involving health and medical workers, including physical therapists, nurses and psychotherapists, are on the rise. Despite the increased incidence of sexual harassment, prior studies show that physical therapists, nursing assistants and caregivers are not doing well cope with sexual harassment. Therefore this study examines the factors associated with sexual harassment damage experience among physical therapists, as well as the relationship between sexual harassment damage experience and job-related aspects. It is intended to prepare basic data for programs and research that can mediate these issues. Methods : We conducted a self-reported questionnaire survey of 200 physical therapists working at medical institutions in the Seoul metropolitan area. The survey items included sexual harassment experience and job-related aspects such as satisfaction, stress, burnout, and engagement. A correlation analysis was conducted to clarify the relationship between sexual harassment experience and job-related factors, and multiple regression analysis was conducted to verify the correlations of sexual harassment experience on physical therapists' job. Results : There was a weak correlation between sexual harassment experience, job satisfaction, and job engagement, and a moderate correlation between sexual harassment experience, job stress, and job burnout. The impact of sexual harassment experience on job had a significant correlation on job satisfaction, job stress and burnout. Conclusions : Sexual harassment damage experience among physical therapists had a significant impact on many job aspects. Thus, there is a need for countermeasures and education to prevent sexual harassment, or at least effectively cope with the consequences. It is proposed to expand to other local or national units as follow-up studies, to study other factors affecting sexual harassment damage experience, and to develop and verify programs to cope with or prevent sexual harassment damage experience.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.13-20
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• 2021

In this paper, a new algorithm is proposed to estimate the damage size by combining the reflected area with the reflected position and extracting contours in proportion to the maximum value of pixels from the visible image. The cumulative summation feature vector algorithm is used to obtain the area of the reflected signal. To get the position of the reflected signal, the signal correlation algorithm is used to decompose the reflected signal from the damage. The proposed algorithm is tested and validated for composite panels. Repetitive experiments are performed and it is confirm that the proposed algorithm is reproducible. Further, it is verified that the damage size can be estimated appropriately by the proposed algorithm.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.4
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• pp.425-433
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• 2001

A correlation between fatigue damage and acousto-ultrasonic (AU) parameters has been obtained from signals acquired during fatigue loading of the single-lap joints of a carbon-fiber reinforced plastic (CFRP) laminates and A16061 plate. The correlation showed an analogy to those representing the stiffness reduction $(E/E_0)$ of polymer matrix composites by the accumulation of fatigue damage. This has been attributed to the transmission characteristics of acoustic wave energy through bonded joints with delamination-type defects and their influence on the change of spectral content of AU signals. Another correlation between fatigue cycles and the spectral magnitude of acoustic emission (AE) signals has also been found during the final stage of fatigue loading. Both AU and AE can be applied almost in real-time to monitor the evolution of damage during fatigue loading.