• Structural Engineering and Mechanics
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• v.77 no.6
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• pp.735-744
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• 2021

In recent years, the use of new materials and technologies with the aim of developing high-performing and cost-effective structures has greatly increased. Application of high-strength concrete (HSC) has been found effective in reducing the dimensions of frame members; nonetheless, such reduction in dimensions of structural elements in the most cases may result in the lack of accountability in the tolerable drift capacity. On this basis, strengthening of frame members using fiber reinforced polymers (FRPs) may be deemed as an appropriate remedy to address this issue, which albeit requires comprehensive and systematic investigations. In this paper, the performance of properly-designed, two-dimensional frames made of high-strength concrete and strengthened with Carbon Fiber Reinforced Polymers (CFRPs) is investigated through detailed numerical simulation. To this end, nonlinear dynamic time history analyses have been performed using the Seismosoft software through application of five scaled earthquake ground motion records. Unstrengthened (bare) and strengthened frames have been analyzed under seismic loading for performance assessment and comparison purposes. The results and findings of this study show that use of CFRP can be quite effective in seismic response improvement of high-strength-concrete structures.

• Journal of Technologic Dentistry
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• v.44 no.3
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• pp.104-110
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• 2022

Purpose: This study analyzes the difficulty and discrimination of the paper-based test (PBT) and the computer-based test (CBT) according to item response theory, focusing on the National Dental Technician Examination. Methods: A mock test was conducted from September 15 to 23, 2020, and the final 179 (1 out of 180 absentees)people were the subjects of this study. Both frequency analysis and factor analysis were performed. The collected data were analyzed using IBM SPSS Statistics ver. 18.0 (IBM) and jMetrik programs. The significance level was set to 0.05. Results: The difficulty of the mock test was more easily responded to in CBT. It was also predicted that the CBT could better measure the ability of test takers than the PBT could. Conclusion: The difficulty, discrimination, and reliability of the questions were not affected by the examination method through the mock test. The feasibility of a future change to the CBT was confirmed by the National Dental Technician Examination.

• Structural Monitoring and Maintenance
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• v.8 no.4
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• pp.379-402
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• 2021

Traditional approaches for structural health monitoring (SHM) seldom take ambient uncertainty (temperature, humidity, ambient vibration) into consideration, while their impacts on structural responses are substantial, leading to a possibility of raising false alarms. A few predictors model-based approaches deal with these uncertainties through complex numerical models running online, rendering the SHM approach to be compute-intensive, slow, and sometimes not practical. Also, with model-based approaches, the imperative need for a precise understanding of the structure often poses a problem for not so well understood complex systems. The present study employs a data-based approach coupled with Empirical mode decomposition (EMD) to correlate recorded response time histories under varying temperature conditions to corresponding damage scenarios. EMD decomposes the response signal into a finite set of intrinsic mode functions (IMFs). A two-dimensional Convolutional Neural Network (2DCNN) is further trained to associate these IMFs to the respective damage cases. The use of IMFs in place of raw signals helps to reduce the impact of sensor noise while preserving the essential spatio-temporal information less-sensitive to thermal effects and thereby stands as a better damage-sensitive feature than the raw signal itself. The proposed algorithm is numerically tested on a single span bridge under varying temperature conditions for different damage severities. The dynamic strain is recorded as the response since they are frame-invariant and cheaper to install. The proposed algorithm has been observed to be damage sensitive as well as sufficiently robust against measurement noise.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.1
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• pp.97-115
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• 2022

Smart power grid is a user friendly system that transforms the traditional electric grid to the one that operates in a co-operative and reliable manner. Demand Response (DR) is one of the important components of the smart grid. The DR programs enable the end user participation by which they can communicate with the electricity service provider and shape their daily energy consumption patterns and reduce their consumption costs. The increasing demands of electricity owing to growing population stresses the need for optimal usage of electricity and also to look out alternative and cheap renewable sources of electricity. The solar and wind energy are the promising sources of alternative energy at present because of renewable nature and low cost implementation. The proposed work models a smart home with renewable energy units. The random nature of the renewable sources like wind and solar energy brings an uncertainty to the model developed. A stochastic dual descent optimization method is used to bring optimality to the developed model. The proposed work is validated using the simulation results. From the results it is concluded that proposed work brings a balanced usage of the grid power and the renewable energy units. The work also optimizes the daily consumption pattern thereby reducing the consumption cost for the end users of electricity.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.66-74
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• 2023

In this study, a new potentiometric sensor selective to copper(II) ions was developed and characterized. The developed sensor has a polymeric membrane and contains 4.0% electroactive material (ionophore), 33.0% poly(vinyl chloride) (PVC), 63.0% bis(2-ethylhexyl)sebacate (BEHS) and 1.0% potassium tetrakis(p-chlorophenyl)borate (KTpClPB). This novel copper(II)-selective sensor exhibits a Nernstian response over a wide concentration range from 1.0×10^-6 to 1.0×10^-1 mol L^-1 with a slope of 29.6 (±1.2) mV decade^-1, and a lower detection limit of 8.75×10-7 mol L^-1. The sensor, which was produced economically by synthesizing the ionophore in the laboratory, has a good selectivity and repeatability, fast response time and stable potentiometric behaviour. The potential response of the sensor remains unaffected of pH in the range of 5.0-10.0. Based on the analytical applications of the sensor, we showed that it can be used as an indicator electrode in the quantification of Cu²⁺ ions by potentiometric titration against EDTA, and can also be successfully utilized for the determination of copper(II) ions in different real samples.

• Steel and Composite Structures
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• v.42 no.1
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• pp.107-121
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• 2022

Past studies have shown that the aspect ratio (width-to-height) of a steel plate shear wall (SPSW) can significantly affect its seismic response. SPSWs with lower aspect ratio (narrow SPSW) may experience low lateral stiffness and flexure dominated drift response. As the height of the frame increases, the narrow SPSWs prove to be uneconomical and demonstrate inferior seismic response than their wider counterparts. Moreover, the thicker web plates required for narrow SPSWs exerts high inward pull on the VBEs. The present study suggests the limiting values of the aspect ratio for an SPSW system by evaluating the seismic collapse performance of 3-, 6- and 9-story SPSW systems using FEMA P695 methodology. For this purpose, nonlinear models are developed. These models are validated with the past quasi-static experimental results. Non-linear static analyses and Incremental dynamic analyses are then carried. The results are then utilized to conservatively suggest the limiting values of aspect ratios for SPSW system. In addition to the conventional-SPSW (Conv-SPSW), the collapse performance of staggered-SPSW (S-SPSW) is also explored. Its performance is compared with the Conv-SPSW and the use of S-SPSW is suggested in the cases where SPSW with lower than recommended aspect ratio is desired.

• Journal of Ocean Engineering and Technology
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• v.37 no.2
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• pp.68-79
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• 2023

Even though submerged breakwater reduces incident wave energy, it redistributes the coastal area's wave-induced current, sediment transport, and morphological change. This study examines the coastal hydrodynamics and the morphological response of a wave-dominated beach with submerged breakwaters installed through field observation and quasi-3D numerical modeling. The pre-and post-storm bathymetry, water level, and offshore wave under storm forcing were collected in Bongpo Beach on the East coast of Korea and used to analyze the coastal hydrodynamic response. Four vertically equidistant layers were used in the numerical simulation, and the wave-induced current was examined using quasi-3D numerical modeling. The shore normal incident wave (east-northeast) generated strong cross-shore and longshore currents toward the hinterland of the submerged breakwater. However, the oblique incident wave (east-southeast) induced the southeastward longshore current and the sedimentation in the northeast area of the beach. The results suggested that the incident wave direction is a significant factor in determining the current and sediment transport patterns in the presence of the submerged breakwaters. Moreover, the quasi-3D numerical modeling is more appropriate for estimating the wave transformation, current, and sediment transport pattern in the coastal area with the submerged breakwater.

• Structural Engineering and Mechanics
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• v.7 no.5
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• pp.457-471
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• 1999

In this paper, different curvature-rates are controlled to highlight the characteristic of viscoplastic response in cyclic bending tests. The curvature-ovalization apparatus, which was designed by Pan et al. (1998), is used for conducting the curvature-controlled experiments on thin-walled tubular specimens for AISI 304 stainless steel under cyclic bending. The results reveals that the faster the curvature-rate implies, the fast degree of hardening of the metal tube. However, the ovalization of the tube cross-section increases when the curvature-rate increases.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.96-97
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• 2018

• The Journal of Korean Physical Therapy
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• v.10 no.1
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• pp.199-212
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• 1998

The purpose of this article is to summary about the application of electromyography and nerve conduction study. Electrodiagnostic studies, which include nerve conduction studies, electromyography, repetitive nerve stimulation, single fiber EMG, late response tests and evoked potential tests are a critical component of the neuromuscular evaluation.