• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1317-1318
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• 2007

On this paper, unimorph type piezoelectric vibrator made by attaching ceramic plates on rectangular elastic body, to find the basic characteristic of the actuators. In experiment, elastic body's displacement and resonance frequency were measured according to changes of ceramic's length and elastic body's length. Also, temperature changes were observed according to time. The displacement and resonance frequency were increased when the ceramic's length were increased. When elastic body's length was increased, the displacement was increased. Also, the temperature was increased according to time, but at some time it was saturated and the temperature was not increased any more.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.10
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• pp.151-156
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• 1997

A laser measurement system, a modified Michelson interferometer, which can accurately measure high speed length and displacement of servomechanisms by detecting a phase shift in the measurement beam using an optical interference was developed. A frequency stabilized laser source and a 20 fold frequency interpolation and digitizing circuit were applied to the system. The refra- ctive index of the ambient air was calibrated through the Edlens formula. The system achieved a resolution of /40, 16nm, a maximum allow-able measurement speed of 600nm/sec, and a length measure- ment range of 1500 mm. Performance of the system was evaluated on the machining center in short and long length measurements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.2
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• pp.163-168
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• 2001

This dissertation describes the development of a sensor for measuring microscopic displacement where we use CoFeSiB amorphous alloy magnetic ribbon having near zero magnetostrictive properties. For the development of the sensor, we first fabricate amorphous alloy magnetic ribbon, and then investigate its physical and magnetic properties. Finally, its possibility of practical application as a displacement sensor is discussed. The experimental samples were made of near zero magnetostrictive (Co$\_$0.94/Fe$\_$0.06/)$\_$9/Si$_2$B$\_$19/ alloy which were fabricated by a rapid liquid quenching method. As a results, we got amorphous alloy magnetic ribbons of 12㎛ in thickness, 10 mm in length, and 2.5 m in width. It was found that the crystallization temperature and the Curie temperature are around 451$\^{C}$ and around 441$\^{C}$ respectively. We couldn't observe any noticeable change of the impedance frequency of 10MHz, but observed the impedance change of 3.76 %/Oe at 100 MHz. The inductance was nearly stable over the frequency range of 1∼10 MHz, In addition, it was observed that the variation of the inductance and the impedance were linear within the displacement ranges of 20∼60㎛. As the results of the experiments, it is suggested that the displacement sensor which is fabricated by using amorphous alloy magnetic ribbon of (Co$\_$0.04/Fe$\_$0.06/)$\_$79/Si$_2$B$\_$19/ compound, can be used as a sensor to detect microscopic displacement.

• The Journal of Korean Physical Therapy
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• v.25 no.3
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• pp.136-142
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• 2013

Purpose: The application of transcutaneous electrical nerve stimulation (TENS) is beneficial for joint movements, inhibition of spasticity, and the improvement of walking ability in patients with chronic hemiplegia. This study aimed to identify the effect of the application of TENS to the knee extensor on the affected side with respect to postural-sway distance and velocity during the sit-to stand movement. Methods: We included 19 patients with post-stroke hemiplegia in this study. They underwent measurements during the sit-to stand movement on a force plate with 5 different stimulation dosages applied over 7 s:No TENS, high-frequency and high intensity TENS, high-frequency and low intensity TENS, low-frequency and high intensity TENS, and low-frequency and low intensity TENS The 5 different condition were administered in random order. Results: The group that received TENS application exhibited a significant decrease in path length and average velocity of center of pressure (COP) displacement compared with the group that did not receive TENS application. TENS dosage at low frequency (3Hz) and high intensity yielded a significant decrease in path length, average velocity, mediolateral distance and anteroposterior distance of COP displacement (p<0.05). Conclusion: Our results demonstrated the effectiveness of the application of low-frequency TENS on STS performance. These findings provide useful information on the application of TENS for the reduction of postural sway during the sit-to-stand movement after stroke.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1115-1119
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• 2005

The paper proposes the elastic modulus evaluation technique of a cantilever beam by vibration analysis based on time-average electronic speckle pattern interferometry (TA-ESPI) with non-contact and nondestructive and Euler-Bernoulli equation. General approaches for the measurement of elastic modulus of thin film are Nano indentation test, Bulge test and Micro-tensile test and so on. They each have strength and weakness in the preparation of test specimen and the analysis of experimental result. ESPI has been developed as a common measurement method for vibration mode visualization and surface displacement. Whole-field vibration mode shape (surface displacement distribution) at a resonance frequency can be visualized by ESPI. And the maximum surface displacement distribution from ESPI is a clue to find the resonance frequency at each vibration mode shape. And the elastic modules of test material can be easily estimated from the measured resonance frequency and Euler-Bernoulli equation. The TA-ESPI vibration analysis technique is able to give the elastic modulus of materials through the simple processing of preparation and analysis.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.115-136
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• 2014

In this study, an extended Kantorovich method, employing multi-term displacement functions, is applied to analyze the vibration problem of symmetrically laminated plates with arbitrary boundary conditions. The vibration behaviors of laminated plates are determined based on the variational principle of total energy minimization and the iterative Kantorovich method. The out-of-plane displacement is represented in the form of a series of a sum of products of functions in x and y directions. With a known function in the x or y directions, the formulation for the variation of total potential energy is transformed to a set of governing equations and a set of boundary conditions. The equations and boundary conditions are then numerically solved for the natural frequency and vibration mode shape. The solutions are verified with available solutions from the literature and solutions from the Ritz and finite element analysis. In most cases, the natural frequencies compare very well with the reference solutions. The vibration mode shapes are also very well modeled using the multi-term assumed displacement function in the terms of a power series. With the method used in this study, it is possible to solve the angle-ply plate problem, where the Kantorovich method with single-term displacement function is ineffective.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.122-129
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• 2012

This study investigates structural and vibration analyses according to the thickness of bicycle frame tube. The model of bicycle frame has the dimension as length of 862mm, width of 100mm and hight of 402.5mm. There are 3 kinds of models with tubes of top, down and seat at bicycle frame as thicknesses of 10, 15 and 20mm. The maximum displacement and stress occur at the center part of seat stay and at the installation part of rear wheel respectively. Maximum displacements become 0.031936, 0.029159 and 0.027984mm in cases of thicknesses of 10, 15 and 20mm respectively. In case of thickness of 20mm among 3 cases, maximum displacement becomes lowest. But maximum stresses become 10.019, 8.5492 and 9.2511MPa in cases of thicknesses of 10, 15 and 20mm respectively. In case of thickness of 15mm among 3 cases, maximum stress becomes lowest. There is no resonance at practical driving conditions and natural frequency remains almost unchanged along the change of thickness. In case of the displacement due to vibration mode, the displacement difference at thickness between 15mm and 20mm becomes 1/2 times than that between 10mm and 15mm. Design at bicycle frame tube becomes most economical and durable effectively in case of thickness of 15mm among 3 cases.

• Macromolecular Research
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• v.14 no.6
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• pp.624-629
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• 2006

The cellulose-based, Electroactive Paper (EAPap) has recently been reported as a smart material with the advantages of lightweight, dry condition, biodegradability, sustainability, large displacement output and low actuation voltage. However, it requires high humidity.. This paper introduces an EAPap made with a cellulose solution and lithium chloride (LiCl), which can be actuated in room humidity condition. The fabrication process, performance test and effect of LiCl content of the EAPap actuator are illustrated. The bending displacement of the EAPap actuators was evaluated with actuation voltage, frequency, humidity and LiCl content changes. At a LiCl/ cellulose content of 3:10, the displacement output was maximized at a room humidity condition. Even though the displacement output was less than that of a high humidity EAPap actuator, the mechanical power output was not reduced due to the increased resonance frequency, which is promising for developing EAPap actuators that are less sensitive to humidity.

• Elastomers and Composites
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• v.38 no.4
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• pp.334-341
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• 2003

A bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is a hollow cylinder, which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the force applied to the shaft and the relative deformation of a bushing is nonlinear and exhibits features of viscoelasticity. A force-displacement relation for bushings is important for multibody dynamics numerical simulations. For the nonlinear viscoelastic axial response, Pipkin-Rogers model, the direct relation of force and displacement, has been derived from Lianis model and the sinusoidal input was used fer Pipkin-Rogers model, and the affection of displacement with frequency change was studied with Pipkin-Rogers model.

• Nuclear Engineering and Technology
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• v.33 no.6
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• pp.619-625
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• 2001

An axial-flow-induced vibration model was proposed for a rod supported by two translational springs at both ends. For developing the model, a one-mode approximation was made based on the assumption that the first mode was dominant in vibration behavior of the single span rod. The first natural frequency and mode shape functions for the flow-induced vibration, called the FIV model were derived by using Lagrange＇s method. The vibration displacements at reactor conditions were calculated by the proposed model for the spring-supported rod and by the previous model for the simple-supported(55) rod. As a result, the vibration displacement for the spring-supported rod was larger than that of the 55 rod, and the discrepancy between both displacements became much larger as flow velocity increased. The vibration displacement for the spring-supported rod appeared to decrease with the increase of the spring constant. AS flow velocity increased, the increase rate of vibration displacement was calculated to go linearly up, and that of the rod having the short span length was larger than that of the rod having the long span length although the displacement value itself of the long span rod was larger than that of the short one.