• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.235-244
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• 2021

This study analyzes the applicability of limit state design method on bridge evaluation by considering the experiment of the existing bridge. The test strength of the member is obtained from the PSC beam bridge experiment. The test strength is compared with the calculated strength obtained from the statistical characteristics of material test strength and the two values are almost the same. The response modification factor and dynamic impact factor are obtained from the vehicle loading test. The rating factor is calculated by applying limit state design method as well as current evaluation method and the results are compared. The reliability index of the test bridge is calculated by using the statistical properties of the member strength obtained from material test and simulation. When the statistical properties of the PSC beam tested in this study are applied, the reliability index with a larger value was obtained than the reliability index obtained with the statistical properties of the design code.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.115-121
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• 2009

The paper presents a signal-based damage detection algorithm of ARX model using dynamic acceleration data. An ARX model correlates acceleration data measured at two locations in a structure by considering those two sets of data as input and output signals. For detecting damage, the error between the measured data and the predicted response from the defined ARX model is computed in time and used for a statistical evaluation. A normal distribution function from the error in time is constructed and its statistical characteristic values are used for the evaluation of damage. By comparing the normal distribution functions before and after damage, three different types of damage indices are proposed. The efficiency and limitation of the proposed algorithm with the statistical evaluation of damage indices have been examined and discussed through laboratory experiments.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.257-262
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• 2009

Elastic-Plastic structural analysis was performed to evaluate structural characteristic and integrity for rocket motor case of solid propulsion system. The structural analyses were compared and evaluated using the simplified 2-D axisymmetric model and 3-D full model for rocket motor case with torispherical dome type. And pre-tension load for bolt model was considered in structural analysis. The results of displacement and stress for the simplified 2-D axisymmetric model and 3-D full model were in an good agreement with each other. Therefore, the simplified 2-D axisymmetric model for rocket motor case was recommended to verify quickly the structural integrity and save the modeling and calculating time in initial design stage. Also, the structural characteristic and integrity for rocket motor case according to 5 dome types was evaluated to select the optimal dome shape.

• Geomechanics and Engineering
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• v.22 no.4
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• pp.291-303
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• 2020

The deformation of the rock surrounding a tunnel manifests due to the stress redistribution within the surrounding rock. By observing the deformation of the surrounding rock, we can not only determine the stability of the surrounding rock and supporting structure but also predict the future state of the surrounding rock. In this paper, we used grey system theory to analyse the factors that affect the deformation of the rock surrounding a tunnel. The results show that the 5 main influencing factors are longitudinal wave velocity, tunnel burial depth, groundwater development, surrounding rock support type and construction management level. Furthermore, we used seismic prospecting data, preliminary survey data and excavated section monitoring data to establish a neural network learning model to predict the total amount of deformation of the surrounding rock during tunnel collapse. Subsequently, the probability of a change in deformation in each predicted section was obtained by using a Bayesian method for detecting change points. Finally, through an analysis of the distribution of the change probability and a comparison with the actual situation, we deduced the survey mark at which collapse would most likely occur. Surface collapse suddenly occurred when the tunnel was excavated to this predicted distance. This work further proved that the Bayesian method can accurately detect change points for risk evaluation, enhancing the accuracy of tunnel collapse forecasting. This research provides a reference and a guide for future research on the probability analysis of tunnel collapse.

• Korean Journal of Biological Psychiatry
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• v.9 no.2
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• pp.152-158
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• 2002

Background & Purpose:Neuropsychological disorders after traumatic brain injury(TBI) are poorly correlated with structural lesions detected by structural neuroimaging techniques such as computed tomography(CT) scan or magnetic resonance imaging(MRI). It is well known that patients with TBI have cognitive and behavioral disorders even in the absence of structural lesions of the brain. This study investigated whether there are abnormalities of regional cerebral blood flow(rCBF) in TBI patients without structural abnormality on MRI, using technetium 99m ethyl cysteinate dimer(Tc-99m-ECD) single photon emission computed tomography(SPECT) scans. Materials and Methods:Twenty-eight TBI patients without structural abnormality on MRI(mild, n=13/moderate, n=9/severe, n=6) and fifteen normal controls were scanned by SPECT. A voxel-based analysis using statistical parametric mapping(SPM) was performed to compare the patients with the normal controls. Results:rCBF was reduced in the right uncus and the right lateral orbitofrontal gyrus in the TBI patients. However, no increase of rCBF was noted in the patients in comparison to the normal controls. Conclusions:These results suggest that the TBI patients, even in the absence of structural lesion of the brain, may have dysfunction of the brain, particularly of the orbitofrontal and anterior pole of the temporal cortex. They also suggest that SPECT can be a useful method to identify brain dysfunctions in combination with structural brain imaging and neuropsychological tests.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.3
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• pp.296-302
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• 2008

Recently, a mesh-size insensitive structural stress definition (structural stress method) is proposed that gives a stress state at weld toe with a relatively large mesh size. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of weld toe. In this study, a fatigue strength assessment for a side shell connection of a container vessel using both the hot spot stress and the Battelle structural stress method was carried out. A consistent approach to compute the extrapolated hot spot stress for design purpose is described and current fatigue guidance is evaluated. Fatigue strength predicted by the two methodologies, e.g. hot spot stress and structural stress approaches, at hot spot locations of a typical ship structure are compared and discussed.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.66-73
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• 2019

The objective of this study was to evaluate the structural safety of the basic design for the linear actuator for the flap control of aircrafts. The kinetic behavior of the linear actuator was determined using the multi-body dynamics (MBD) analysis, and the contact force was calculated to be used as input data for the structural analysis based on the finite element analysis. In the structural analysis, the thermal and static behaviors of the linear actuator satisfying the designed velocity were examined, and the structural safety of the linear actuator evaluated. Moreover, the dynamic behaviors of the key components of the linear actuator were investigated by the modal analysis. The actuation rod linearly moved with about 5 mm/s when the motor operated at 225 rpm and the maximum contact force of 32.83 N occurred between two driving gears. Meanwhile, the structural analysis revealed that the maximum thermal and static stresses were 1.57% and 78% of the yield strength of steel, respectively, and they were in a safe range of the structure. In addition, the linear actuator for the basic design is stable to the resonance by avoiding the natural frequencies of the components.

• Earthquakes and Structures
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• v.16 no.5
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• pp.611-623
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• 2019

A set of mid-rise bare and uniformly infilled reinforced-concrete frame buildings are analyzed for two different seismic intensities of ground-motions (i.e., 'Design Basis Earthquake' and 'Maximum Considered Earthquake') to study their floor response. The crucial parameters affecting seismic design force for acceleration-sensitive non-structural components are studied and compared with the guidelines of the European and the United States standards, and also with the recently developed NIST provisions. It is observed that the provisions of both the European and the United States standards do not account for the effects of the period of vibration of the supporting structure and seismic intensity of ground-motions and thereby provides conservative estimates of the in-structure amplification. In case of bare frames, the herein derived component amplification factors for both the design basis earthquake and the maximum considered earthquake exceeds with their recommended values in the European and the United States standards for non-structural components having periods in vicinity of the higher modes of vibration, whereas, in case of infilled frames, component amplification factors exceeds with their recommended value in the European standard for non-structural components having periods in vicinity of the fundamental mode of vibration, and only for the design basis earthquake. As a consequence of these observations, as well as capping on the design force (in case of United states standard and NIST provisions), in case of the design basis earthquake, the combined amplification factor is underestimated for non-structural components having periods in vicinity of the higher modes of vibration of bare frames, and also for non-structural components having periods in vicinity of the fundamental mode of vibration of infilled frames. At the maximum considered earthquake demand, excepting non-structural components having periods in vicinity of the higher modes of vibration of bare frames, all provisions generally provide conservative estimates of the design floor accelerations.

• Journal of Korean Academy of Nursing
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• v.40 no.1
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• pp.1-13
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• 2010

Purpose: The purpose of this study was to develop evaluation criteria for conversations about medication and to demonstrate conversational analysis with actual dialogues on medication as examples. Methods: This study was a secondary analysis of qualitative research using conversational analysis which showed functional phases and patterns of dialogue about medication (greeting, identifying the patient, medicating, finishing). Nurse-patient conversations were videotaped and transcribed and 75 conversations were used for analysis. Results: Not all functional phases were showed in the conversations about medication. Therefore, conversations about medication can be considered as incomplete dialogues. The evaluation-criteria were represented in terms of the structure and content of the dialogues. Structural evaluation-criteria were the same as the functional phases, as functional stage is the standard for evaluation. The criteria of evaluation for content suggested 3 domains, content, expression, and interaction with 20 items scored on a Likert-type scale of 5-points. Finally, analysis of actual conversations about medication according to the evaluative criteria were provided. Conclusion: The results provide the basic data to develop educational programs and strategies to improve nurses’ competency in conversation about medication.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.37-48
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• 2003

A study for the structural strength evaluation of doubler plates subjected to the in-plane combined load and lateral pressure load has been performed through a systematic evaluation process. In order to properly estimate the static strength of doubler plate, elasto-plastic large deflection analysis is introduced including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed based on the analysis results. Also, in order to compare the doubler structure with the original strength of main plate without doubler, a simple formula for the evaluation of the equivalent flat plate thickness is derived based on the additional series analysis of fiat plate structure. Using this derived equation, the thickness change of a equivalent flat plate is analyzed according to the variation of various design parameters of doubler plate and some design guides are suggested In order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent plate thickness formula and the developed buckling strength formulas for intact plates by author et al. is discovered and these relations are formulated for the future development of simple strength evaluation formula of doubler plate structure.