• Journal of the Korean Wood Science and Technology
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• v.39 no.5
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• pp.398-405
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• 2011

Nondestructive evaluation (NDE) technique method using a resonance frequency mode was carried out for woodceramics made by different phenol resin impregnation ratios (40, 50, 60, 70%) for Broussonetia Kazinoki Sieb. Dynamic modulus of elasticity increased with increasing resin impregnation ratios. There was a close relationship between dynamic modulus of elasticity and static bending modulus of elasticity and between dynamic modulus of elasticity and MOR and between static bending modulus of elasticity and MOR. Therefore, the dynamic modulus of elasticity using resonance frequency mode is useful as a nondestructive evaluation method for predicting the MOR of woodceramics made by different impregnation ratios.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.23-28
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• 2004

Seat is one of the most important part of an automobile for passenger's safety especially when an accident happens. A recliner is a part of the seat assembly, having the function of adjusting the back-plate angle of a seat. Recently, many kinds of vehicles have adopted the round recliner module rather than the conventional types of recliners because of its broad compatibility and structural simplicity. In this study a two-dimensional finite element strength analysis has been performed using a commercial code ABAQUS/Standard for the purpose of developing a new round recliner model. The loading condition for the analysis is the same as the FMVSS 301 regulation. The finite element result for the round recliner has been compared with that for the conventional type.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.58-64
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• 2003

A mechanical press joining was investigated in ender for joining A1-5052 sheets for automobile body weight reduction. Static tensile and fatigue tests were conducted using tensile-shear specimens for evaluation of fatigue strength of the joint. During Tox joining process for A1-5052 plates, using the current sheet thickness and punch diameter, the optimal applied punching force was found to be 32 kN under the current joining condition. For the static tensile-shear experiment results, the fracture mode is classified into interface fracture mode, in which the neck area fractured due to influence of neck thickness, and pull-out fracture mode due to influence of plastic deformation of the joining area. And, during fatigue tests for the A1-5052 tensile shear specimens, interface failure mode occurred in the region of low cycle. The fatigue endurance limit approached to 6 percents of the maximum applied load, considering fatigue lifetime of $2.5\times10^6$ cycles.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.3
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• pp.27-37
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• 2018

PURPOSE: The purpose of this study was to investigate and evaluate muscle activity and foot pressure during gait, and isokinetic strength and balance in persons with functional ankle instability (FAI). METHODS: Nine healthy subjects (CON, n=9) without FAI and 11 patients (FAI, n=11) with FAI participated in the study after having been screened with an ankle instability instrument and a balance error scoring system. In addition, FAI was classified as non-involved (FAI-N) or involved (FAI-I), and CON was classified as dominant or non-dominant. All subjects were evaluated for isokinetic strength (plantar flexion, dorsiflexion, inversion and eversion of $30^{\circ}/sec$ and $60^{\circ}/sec$), balance (static and dynamic), muscle activity (tibialis anterior, peroneus longus and gastrocnemius) and foot pressure (static and dynamic) during gait. RESULTS: Results showed that plantar flexion (p<.05), dorsiflexion (p<.05), inversion (p<.01) and eversion (p<.00) of $60^{\circ}/sec$ were significantly decreased in FAI-I compared to those in FAI-N and CON. C 90 of static balance with eyes open (p<.01) and closed (p<.00) were significantly increased in FAI compared to those in CON. Forward position of dynamic balance (p<.01) was significantly decreased in FAI compared to that in CON. Gastrocnemius and peroneus longus of dynamic muscle activity (p<.01), left and right weight distribution of static foot pressure (p<.00) and pressure distribution of dynamic foot pressure (p<.00) were significantly decreased in FAI-I compared to those in FAI-N. CONCLUSION: We demonstrated that ankle strength, balance, muscle activity and foot pressure were significantly correlated with FAI.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2277-2286
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• 2002

The application of bonded dissimilar materials to industries as automobiles, aircraft, rolling stocks, electronic devices and engineering structures is increasing gradually because these materials, compared to the homogeneous materials, have many advantages for material properties. In spite of such wide applications of bonded dissimilar materials, the evaluation method of quantitative strength considering the stress singularities for its bonded interface has not been established clearly. In this paper, the stress singularity for Bctors and the stress intensity factors were analyzed by boundary element method(BEM) for the scarf joints of Al/Epoxy with and without a crack, respectively. From static fracture experiments of the bonded scarf joints, a fracture criterion and a evaluation method of interface strength in bonded dissimilar materials were proposed and discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1298-1304
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• 2006

The present paper is aiming at the evaluation for failure mechanisms and static strength of brazed joints used in household electronics. For these purposes, the failure analysis was performed on the various brazed joints, through the bursting, the micro-Victors hardness tests and 3-dimensional X-ray technique. The failure modes of brazed joints were classified into two different types, based on the results of bursting pressure test by means of self-designed internal-pressure testing machine. Their failure mechanism was dependent on the relationship between heat effect occurred in manufacturing process and internal flaws such as incomplete penetration and pin hole. Also, a finite element analysis was performed to evaluate the stress distribution with respect to the heat and the internal flaws.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.775-779
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• 2007

The structural strength assessment of a carbody was performed using F.E. analysis and static test to verify the structural safety of newly manufactured carbody of a freight car. The freight car for the transportation of cold-rolled coils in steel making company was designed with SS400 steel for underframe and SM490A steel for bracket. Prior to the evaluation of structural strength, commercial finite element method(FEM) software was used for the stress and structural analyses on stress distribution in a carbody of freight car. The strain gages were attached on the carbody based on the FEM results. The actual vertical loading test and horizontal compression loading test were conducted, and the stress and displacement were obtained. Finally, the structural strength of carbody was evaluated by using a engineering techniques.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.4
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• pp.50-60
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• 1995

Recently advantages joining dissimiliar materials and light weight material techniques have led to increasing use of structural adhesives in the various industries. Stress singulartiy occurs at the interface edges of adhesively bonded dissimilar materials. So it is required to analyze its stress singularity at the interface edges of adhesively bonded joints indissimilar materials. In this paper, the analysis method of stress singularity is studied in detail. Also, effects of the stress singularity at the interface edge of adhesively bonded scarf joints in combinations of dissimilar materials are investigated by using 2-dimensional elastic program of boundary element method. As the results, the strength evaluation method of adhesively bonded dissimilar materials using the stress singularity factor, $\Gamma$,is very useful. The fracture criterion, method of strength evaluation and prediction of fracture strength by the stress singularity factor on the adhesively bonded dissimilar materials are proposed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.471-478
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• 2018

Static tests of the composite wing structure were performed to verify damage tolerance design. Both 5 cases of DLLT and 3 cases of DULT were completed to meet requirements for static strength. After inducing BVID and open hole damages on the critical areas of the composite wing based on associated regulations, the DULT and fracture test were performed. In major wing parts, the measured strains and displacements agreed well with those of structural analysis. The initial structural fracture occurred at the area having minimum margin of safety as expected by analysis. As a result, it was confirmed that results from analytic model and strength evaluation were similar to behaviors of the composite wing structure.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.87-92
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• 2005

It has been well hewn that ductile fracture of steels is accelerated by triaxial stresses. The characteristics of ductile crack initiation in steels are evaluated quantitatively using a two-parameters criterion based on equivalent plastic strain and stress triaxiality. The present study focuses on the effects of strength mismatch, which can elevate plastic constraint due to heterogeneous plastic straining, on the critical condition for ductile fracture initiation usinga two-parameter criterion. Fracture initiation testing has been conducted under static loading using notched round bar specimens which had different notch locations. This study provides the fundamental clarification of the effect of strength mismatching and effect of notch location on the critical condition to ductile crack initiation from notch root using fuite element method and ultrasonic-mechatronics system. The critical condition of ductile crack initiation from notch root of strength mismatched tensile specimens under static loading appeared to be almost the same as those of homogeneous tensile specimens with circumferential sharp notch specimen. Also, the effect of notch location in mismatched specimens was estimated using finite element(FE) analyses.