• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1113-1118
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• 2004

This paper presents the dynamic analysis method for an electromechanical system. The engineer has at his disposal a variety of software simulation tools. However, difficulties arise when the study of the behavior of complex electromechanical systems in combination with coupling element is required. Typical examples of such systems are machines for factory automation, home automation, and office automation. Dynamic systems analysis packages or electronic systems analysis packages offer the restrictive to simulate these mixed systems such electromechanical product. Electronic circuit analysis algorithm is easily incorporated into a multi-body dynamics analysis algorithm. The governing equation of electronic circuit is formulated as a differential algebraic equation form including both electrical and mechanical variables and is simultaneously solved in every time step. This analysis method clearly demonstrates the application potential for mixed electromechanical simulation.

• Smart Structures and Systems
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• v.19 no.4
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• pp.361-369
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• 2017

Electromechanical impedance method as an efficient tool in Structural Health Monitoring (SHM) utilizes the electromechanical impedance of piezoelectric materials which is directly related to the mechanical impedance of the host structure and will be affected by damages. In this paper, electromechanical impedance of piezoelectric patches attached to simply support rectangular plate is determined theoretically and experimentally in order to detect damage. A pairs of piezoelectric wafer active sensor (PWAS) patches are used on top and bottom of an aluminum plate to generate pure bending. The analytical model and experiments are carried out both for undamaged and damaged plates. To validate theoretical models, the electromechanical impedances of PWAS for undamaged and damaged plate using theoretical models are compared with those obtained experimentally. Both theoretical and experimental results demonstrate that by crack generation and intensifying this crack, natural frequency of structure decreases. Finally, in order to evaluate damage severity, damage metrics such as Root Mean Square Deviation (RMSD), Mean Absolute Percentage Deviation (MAPD), and Correlation Coefficient Deviation (CCD) are used based on experimental results. The results show that generation of crack and crack depth increasing can be detectable by CCD.

• Structural Engineering and Mechanics
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• v.33 no.4
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• pp.539-542
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• 2009

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1862-1870
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• 2020

The purpose of this study is to investigate the effect of welding residual stress on operating stress in designing a nuclear turbine welded rotor. A two-dimensional axisymmetric finite element model is employed to calculate the residual stress before and after post weld heat treatment (PWHT), and then the superposition of residual stress after PWHT and operating stress at normal speed and overspeed were discussed. The investigated results show that operating stress can be affected significantly by welding residual stress, and the distribution trend of superposition stress at the weld area is mainly determined by welding residual stress. The superposition of residual stress and operating stress is linear superposition, and the hoop stress distribution of superposition stress is similar with the distribution of residual stress. With the increasing overspeed, the distribution pattern of the hoop superimposed stress remains almost unchanged, while the stress level increases.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.35-39
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• 2008

In this study, electromechanical properties of carbon nanotube (CNT) thin film on flexible substrates were measured using a micro-tensile machine with functionality of simultaneous measurements of displacement, load and electrical resistance. The CNT thin film of about 100 nm thick was deposited on flexible substrates, polyethylene terephthalate (PET) using spraying and ink-jetting techniques. To investigate the effect of process condition on the electromechanical properties of CNT thin film, sets of CNT samples were fabricated under various heat treatments and microwave process. The microstructures of the CNT thin film before and after tensile test were investigated using Scanning Electron Microscope (SEM), and the failure modes of the CNT thin films were identified to understand their electromechanical behaviors and interaction with the flexible substrates. Based on the experimental results, the use of CNT thin film as flexible electrodes and strain gages is discussed.

• The Journal of Korean Physical Therapy
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• v.20 no.1
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• pp.41-47
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• 2008

Purpose: This study aimed to assess the effectiveness of gait training with the use of an electromechanical gait trainer with functional electrical stimulation (FES) for patients that had undergone subacute stroke. Methods: The study subjects included nine subacute stroke patients of the Korea National Rehabilitation Center in Seoul, Korea. Outcome was measured using the timed Up and Go test, Fugl-Meyer-L/E assesment, with determination of the comfortable maximal gait speed, composite spasticity score, functional ambulatory category and Berg balance scale. All measured scores were recorded before, during, and after rehabilitation and at an eight-week follow-up. Results: Patients who received electromechanical-assisted gait training in combination with FES after subacute stroke were more likely to achieve independent walking, functional activities, balance and gait speed. Conclusion: The outcome of our gait-training program demonstrates that it may be practical to integrate FES into electromechanical gait training without any adverse effects. However, further randomized controlled studies are needed to evaluate if patient outcome after combined training is superior to outcome after the use of electromechanical gait trainer treatment alone or conventional gait training alone.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.303-304
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• 2003

Conducting polymers show several unique features, wherein electrical and optical properties change drastically during electrochemical reaction. By making use of these phenomena, several electronic devices have been fabricated, for instance, electrochromic displays, rechargeable batteries and electroplasticity memory devices. Electromechanical actuators using conducting polymers have been proposed by Baughman et. al [1]. (omitted)

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.609-614
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• 2014

The fringe field effects on the transient characteristics of nano-electromechanical (NEM) memory cells have been discussed by using an analytical model. The influence of fringe field becomes stronger as the size of a cell decreases. By using the proposed model, the dependency of NEM memory transient characteristics on cell parameters has been evaluated.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.111-117
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• 2005

Several of the conventional hydraulic systems in an automobile are now being replaced by more reliable and energy efficient electromechanical systems. Developments in the brushless permanent magnet machine and in the power and control electronics are the key factors responsible for this transformation. These applications brought out some performance challenges associated with the brushless machines. This paper will focus on these challenges to be able to use these machines in such applications. In terms of replacing hydraulic systems with electromechanical systems, steering system is leading the way in automobiles. Currently, steering systems using Electro-hydraulically assisted systems and Electrically assisted (Electromechanical) systems are in the market. Though the Electrically assisted power steering has several advantages over other systems, certain performance and cost challenges delayed the penetration of such systems in to the market.

• Progress in Superconductivity and Cryogenics
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• v.19 no.4
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• pp.26-30
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• 2017

The promising characteristics of 2G high-temperature superconductor (HTS) coated conductor (CC) tapes have made it possible to apply to various electrical device applications. In this study, the mechanical and electromechanical properties of Sn-Cu double layer stabilized GdBCO CC tapes have been characterized. The stress and strain tolerances of $I_c$ in GdBCO CC tapes adopting stainless steel substrate were evaluated using $I_c$-strain measurement at 77 K under both uniaxial tension and monotonic bending conditions. The results were compared to the conventional single Cu layer stabilized CC tape. As a result, the Sn-Cu double layer stabilized GdBCO CC tapes showed somehow lower or comparable electromechanical properties as compared to the Cu stabilized CC tape ones.