• Journal of the Korean Society for Precision Engineering
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• v.32 no.4
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• pp.377-386
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• 2015

Joint force/torque estimation by inverse dynamics is a traditional tool in biomechanical studies. Conventionally for this, kinematic data of human body is obtained by motion capture cameras, of which the bulkiness and occlusion problem make it hard to capture a broad range of movement. As an alternative, inertial motion sensing using cheap and small inertial sensors has been studied recently. In this research, the performance of inertial motion sensing especially to calculate inverse dynamics is studied. Kinematic data from inertial motion sensors is used to calculate ground reaction force (GRF), which is compared to the force plate readings (ground truth) and additionally to the estimation result from optical method. The GRF estimation result showed high correlation and low normalized RMSE(R=0.93, normalized RMSE<0.02 of body weight), which performed even better than conventional optical method. This result guarantees enough accuracy of inertial motion sensing to be used in inverse dynamics analysis.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.473-478
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• 2003

This paper presents static and dynamic measurement of the stress and motion characteristics for crawler type excavators. Eight scenarios were prepared for static measurement based on two extreme digging positions, maximum digging reach position and maximum digging force position. The measured items for static motion included stress, cylinder pressure, cylinder stroke and digging force. The measured static stresses showed that asymmetric digging force acting on a bucket induced higher stress level than symmetric one. The measured static pressures and digging forces also agreed with design pressures and design digging forces, respectively. The dynamic measurement was performed for two types of motion, that is, simple reciprocation of each cylinder and actual digging motion. The measured items for dynamic motion were stroke and pressure of each cylinder, stresses on the working device and acceleration on the upper plate of an arm. The measured data showed that the natural frequency of the excavator highly depended on the hydraulic stiffness of cylinders. Digging motion tests revealed that digging motion was closer to static motion rather than dynamic one.

• Clinics in Shoulder and Elbow
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• v.26 no.4
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• pp.373-379
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• 2023

Background: The purpose of this study was to determine the association between smoking and clinical outcomes of hook plate fixation for acute acromioclavicular (AC) joint injuries. Methods: This study retrospectively investigated 82 patients who underwent hook plate fixation for acute AC joint dislocation between March 2014 to June 2022. The patients were grouped by smoking status, with 49 in group N (nonsmokers) and 33 in group S (smokers). Functional scores and active range of motion were compared among the groups at the 1-year follow-up. Coracoclavicular distance (CCD) was measured, and difference with the uninjured side was compared at initial injury and 6 months after implant removal. Results: No significant differences were observed between the two groups in demographic factors such as age and sex, as well as parameters related to initial injury status, which included time from injury to surgery, the preoperative CCD difference value, and the Rockwood classification. However, the postoperative CCD difference was significantly higher in group S (3.1±2.6 mm) compared to group N (1.7±2.4 mm). Multivariate regression analysis indicated that smoking and the preoperative CCD difference independently contributed to an increase in the postoperative CCD difference. Despite the radiographic differences, the postoperative clinical outcome scores and active range of motion measurements were comparable between the groups. Conclusions: Smoking had a detrimental impact on ligament healing after hook plate fixation for acute AC joint dislocations. This finding emphasizes the importance of smoking cessation to optimize reduction maintenance after AC joint injury. Level of evidence: III.

• Clinics in Shoulder and Elbow
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• v.15 no.2
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• pp.117-122
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• 2012

Purpose: To assess the effectiveness of internal fixation using a precontoured locking compression plate for the treatment of the displaced clavicle fracture by analyzing both radiological and clinical outcomes. Materials and Methods: We reviewed 34 cases of displaced clavicle shaft fracture treated by internal fixation using precontoured locking compression plates between May 2009 and February 2010. Radiological outcomes were analized on the basis of bone union and the differences between the time for bone union depending on sex and age. Clinical outcomes were analyzed on the basis of quick DASH Scores and the differences in the range of motion of the affected shoulder compared to the contralateral shoulder. Results: In the radiological evaluation, all fractures showed bone union, and the average time for bone union was 12.3 weeks, without delayed unions. Time for bone union did not differ significantly with respect to sex and age (p=0.87). In the clinical evaluation, the average final quick DASH Score was 23.5 (range, 12~42). At final follow up, the range of motion after bone union in the affected shoulder was not significantly different from that of the contralateral shoulder (p=0.69). Conclusion: The internal fixation achieved using precontoured locking compression plate in displaced clavicle shaft fracture showed effective bone union and can be considered as a reliable method with fine clinical results showing early range of motion at the shoulder joint.

• Journal of Advanced Technology Convergence
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• v.2 no.4
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• pp.7-11
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• 2023

In this study, we presented a method to recognize vehicle license plates using CNN techniques. A vehicle plate is normally used for the official identification purposes by the authorities. Most regular Optical Character Recognition (OCR) techniques perform well in recognizing printed characters on documents but cannot make out the registration number on the number plates. Besides, the existing approaches to plate number detection require that the vehicle is stationary and not in motion. To address these challenges to number plate detection we make the following contributions. We create a database of captured vehicle number plate's images and recognize the number plate character using Convolutional Neural Networks. The results of this study can be usefully used in parking management systems and enforcement cameras.

• Structural Engineering and Mechanics
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• v.39 no.6
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• pp.861-875
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• 2011

The aim of the present article is to study the micropolar thermoelastic interactions in an infinite Kelvin-Voigt type viscoelastic thermally conducting plate. The coupled dynamic thermoelasticity and generalized theories of thermoelasticity, namely, Lord and Shulman's and Green and Lindsay's are employed by assuming the mechanical behaviour as dynamic to study the problem. The model has been simplified by using Helmholtz decomposition technique and the resulting equations have been solved by using variable separable method to obtain the secular equations in isolated mathematical conditions for homogeneous isotropic micropolar thermo-viscoelastic plate for symmetric and skew-symmetric wave modes. The dispersion curves, attenuation coefficients, amplitudes of stresses and temperature distribution for symmetric and skew-symmetric modes are computed numerically and presented graphically for a magnesium crystal.

• Tribology and Lubricants
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• v.20 no.4
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• pp.209-217
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• 2004

Lubrication characteristics between a cylinder block and a valve plate for high speed bent-axis type hydraulic pump play an important role in volumetric efficiency and durability of pump. In this paper, a finite element method is presented for the computation of the pressure distribution between a cylinder block and a valve plate for high speed bent-axis type hydraulic pump. Also, a Runge-Kutta method is applied to simulate the cylinder block dynamics of three-degrees of freedom motion. From the results of computation, we can draw two major conclusions. One is related to the fluid film characteristics between a cylinder block and a valve plate and the other is related to the average leakage that is determined by the pressure gradient and the clearance near the discharge port. The numerical results of cylinder block dynamics were compared with the experimental results using eddy-current type gap sensors those are fixed at a pump housing.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.785-791
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• 2002

A modeling method for the dynamic characteristic analysis of a translationally accelerated trapezoidal cantilever plate is presented in this paper. The equations of motion for the plate are derived and transformed into a dimensionless form. The effects of the inclination angles and the acceleration on the vibration characteristics of the plate are investigated. Incidentally, natural frequency loci veering and associated mode shape variations are observed and discussed.

• Structural Engineering and Mechanics
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• v.40 no.4
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• pp.501-515
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• 2011

Sandwich elements have high flexural rigidity and high strength per density. They also have excellent anti-vibration and anti-noise characteristics. Therefore, they are used for structures of airplanes and high speed ships that must be light, as well as strong. In this paper, the Reissner-Mindlin's plate theory is studied from a Hamilton's principle point of view. This theory is modified to include the influence of shear deformation and rotary inertia, and the equation of motion is derived using energy relationships. The theory is applied to a rectangular sandwich model which has isotropic, asymmetrical faces and an isotropic core. Investigations are conducted for five different plate thicknesses. These plates are identical to the sandwich plates currently used in various structural elements of surface effect ships (SES). The boundary conditions are set to simple supports and fixed supports. The elastic and shear moduli are obtained from the four-point bending tests on the sandwich beams.

• Coupled systems mechanics
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• v.5 no.1
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• pp.87-100
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• 2016

In this work, an improved semi-analytical technique is adopted to track the dynamic response of thin rectangular plates excited by sequential traveling masses. This technique exploits a so-called indirect definition of inertial interaction between the moving masses and the plate and leads to a reduction, in the equations of motion, of the number of time-varying coefficients linked to the changing position of the masses. By employing this optimized method, the resonance of the plate can be obtained according to a parametric study of relevant maximum dynamic amplification factor. For the case of evenly spaced, equal masses travelling along a straight line, the resonance velocity of the masses themselves is also approximately predicted via a fast methodology based on the fundamental frequency of the system only.