• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.1072-1076
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• 2001

A biomechanical study was conducted in this study to investigate if in-line skating wrist guards can effectively reduce the impact forces so as to protect the wrist from fracture. The forearm specimens with and without wrist guards were dropped using a specially designed sled to simulate the impact on the wrist while falling. A force plate was used to measure the total impact force on the dropping weight whereas a load cell was attached to the proximal end of the specimen and used to quantify the impact transmitted through the wrist joint. From the non-destructive tests, mean peak force measured from a force plate showed no difference between the guarded and unguarded groups whereas mean impulse of the guarded group was significantly greater than that of the unguarded group (p<0.01). Comparing the peak force and impulse measured from the load cell, the peak force of the guarded group was significantly less than that of the unguarded group (p<0.001), while the impulse values were similar. When the specimens were dropped from a higher position (2.5ft ve. 1ft), all unguarded specimens had severe wrist fractures whereas fracture was found in three out of 5 guarded specimens. Comparison of mean peak forces and impulses showed as significant difference between the guarded and unguarded groups only in the mean impulse measured from the force plate. These results suggest that the wrist guard may protect the wrist by attenuating the peak force transmitted to radius and ulnar although it may not be effective when the wrist is subjected to an impact sufficiently large to cause fractures.

• Advances in aircraft and spacecraft science
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• v.7 no.2
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• pp.115-134
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• 2020

This paper proposes a bending analysis for a functionally graded piezoelectric (FGP) plate through utilizing a two-variable shear deformation plate theory under simply-supported edge conditions. The number of unknown functions used in this theory is only four. The electric potential distribution is assumed to be a combination of a cosine function along the cartesian coordinate. Applying the analytical solutions of FGP plate by using Navier's approach and the principle of virtual work, the equilibrium equations are derived. The paper also discusses thoroughly the impact of applied electric voltage, plate's aspect ratio, thickness ratio and inhomogeneity parameter. Results are compared with the analytical solution obtained by classical plate theory, first-order-shear deformation theory, higher-order shear deformation plate theories and quasi-three-dimensional sinusoidal shear deformation plate theory.

• Journal of IKEEE
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• v.22 no.4
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• pp.1188-1194
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• 2018

This paper proposes an image enhancement-based license plate detection algorithm to improve the overall performance of system. Non-uniform illumination conditions have huge impact on overall plate detection system accuracy. In this paper, we propose an algorithm for color image enhancement-based license plate detection for improving accuracy of images degraded by excessively strong and low sunlight. Firstly, the image is enhanced by Multi-Scale Retinex algorithm. Secondly, a plate detection method is employed to take advantage of geometric properties of connected components, which can significantly reduce the undesired plate regions. Finally, intersection over union method is applied for detecting the accurate location of number plate. Experimental results show that the proposed method significantly improves the accuracy of plate detection system.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.82.2-82.2
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• 2010

The development of bipolar plate having high efficiency and chemical properties has a major impact on fuel cell applications commercialization. Even though graphite bipolar plate has high electric conductivity and chemical resistance, it has demerits about mass production and brittle property for commercialization. Hence, metallic bipolar plate can be substitute for fuel cell bipolar plate. Although its inadequate corrosion behavior under PEMFC environment lead to a deterioration of membrane by dissolved metal ions, metallic bipolar plate for PEMFC is more suitable for automotive and residential power generation system because of its high mechanical strength, low gas permeability and applicability to mass production. Therefore, several types of coating has been applied to prevent corrosion and oxide film growth and to achieve more high durability. This work presents durability of coated metal bipolar plate for low temperature PEMFC which made for fuel cell vehicle. This results showed surface treatment increase long-term durability, even electric conductivity and corrosion resistance.

• Journal of the Society of Disaster Information
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• v.12 no.1
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• pp.62-68
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• 2016

In this study, the impact problems are brought up and the formulation by isoparametric element is attempted for the purpose of analyzing the response characteristics of laminated plate receiving impact load based on the first-order shear deformation theory expanded from the Mindlin plate theory. The result of static analysis and dynamic analysis is drawn through the numerical analysis rectangular and circular plates of antisymmetric Angle-Ply laminated plate using the finite element method and the analysis on each displacement is compared.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.128-129
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• 2006

To investigate impact property characteristics on the low temperature plate weld metal, the two different plates of the same steel grade were welded and evaluated by Mo bearing and no Mo containing welding consumables. The results are summarized as follows; 1) Multi pass welded Mo bearing weldment was not satisfied with the requirement of tensile strength, while no Mo containing one was satisfied with it 2) In the plate butt weldment, the impact property of weld metal was highly affected by both the welding consumable and plate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3211-3223
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• 1996

In this paper, the propagation of elastic wave generated by loading impact to plates made of isotropic of anisotropic material was studied. And the influence of boundary conditions (free or clamped edge) upon the reflection of elastic wave was anlyzed. Also, double exposure holographic interferometer using ruby pulse laser was formed in order to investigate transient waves. Before the elasitc wave was reflected from the edges, the elastic wave of isotropic plate such as aluminum plate showed circular interferometric fringe pattern, whereas that of anisotropic plate such as epoxy composite laminates showed elliptical one. And the transverse displacement curves obtained from experiment and theory for both plates agreed well. Also, the waves reflected from the boundary edges showed much differences according to the boundary condition of edges.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.274-277
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• 1999

This paper is concerned with estimating the mass of a loose part in the steam generator of a nuclear power plant. Although there is the basic principle known as “Hertz Theory”for estimating mass and energy of a spherical part impacted on an infinite flat plate, the theory is not directly applicable because real plants do not comply with the underlying ideal assumptions. (Say, the steam generator is of a cylindrical and hemisphere shape.) In this work, a practical method is developed based on the basic theory and considering amplitude and energy attenuation effects. Actually, the impact waves propagating along the plate to the sensor locations become significantly different in shape and frequency spectrum from the original waveform due to the plate and surrounding conditions, distance attenuation and damping loss. To show the validity of the present mass estimation algorithm, it has been applied to the mock-up impact test data and also to real plant data. The results show better performance comparing to the conventional Hertz schemes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.936-941
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• 2005

Apartment building floor with a damping layer can be modeled as a sandwich plate. In order to reduce low frequency noise more efficiently due to heavy impact on such a floor, thickness of the damping layer needs to be optimized at the design stage. Modal loss factors are determined in this paper by RKU equation which is popular In sandwich plate theories. Optimum damping layer thickness determined at each mode is weighted so that several modes in the frequency range of interest can be included in a more systematic way. Furthermore, to reflect frequency-dependent characteristics of complex stiffness of the damping layer, an iteration method is proposed in finding modal frequencies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.139-149
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• 2002

An explicit direct time integration method based solution algorithm is proposed to predict dynamic postbuckling response of thin plates. Based on the von Karman's plate equations and Marquerre's shallow shell theory, a rectangular plate finite element is formulated and utilized in this study. The element formulation takes into account geometrical nonlinearity and initial deflection of plates. The solution algorithm employs the central difference method. Using the computer program developed by the authors, dynamic postbuckling behavior of elastic thin plates under impact loading is investigated by considering the time variation of load and load duration. The efficiency of the proposed solution algorithm is examined through illustrative numerical examples.