• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1442-1445
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• 2005

Several test methods, including micro strain/deformation measurement techniques, have been studied to more reliably measure the micro properties in micro/nano materials. Therefore, in this study, the continuous measurement of in-plane tensile strain in micro-sized specimens of thin film materials was introduced using the micro-ESPI technique. TiN and Au thin films 1 and $0.47\;\mu{m}$ thick, respectively, were deposited on the silicon wafer and fabricated into the micro-sized tensile specimens using the electromachining process. The micro-tensile loading system and micro-ESPI system were developed to measure the tensile strain during micro-tensile test. The micro-tensile stress-strain for these materials was determined using the algorithm for continuous strain measurement. Furthermore, algorithm for enhancing the sensitivity to measurement of in-plane tensile strain was suggested. According to the algorithm for enhancement of sensitivity, micro-tensile strain data between interfringe were calculated. It is shown that the algorithm for enhancement of the sensitivity suggested in this study makes the sensitivity to the in-plane tensile strain increase.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.148-151
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• 2005

This paper is concerned with the thermo-mechanical behavior and temperature dependent strain rate sensitivity of steel sheet for an auto-body. In order to Identify the temperature dependent strain rate sensitivity of SPRC35R and SPRC45E, uniaxial tension tests are performed with the variation of the strain rates from 0.001/sec to 200/sec, and the variation of environmental temperatures from $-40^{\circ}C\;to\;200^{\circ}C$. The thermo-mechanical response at the quasi-static state is obtained with the static tensile test and at the intermediate strain rate is from the high speed tensile test. The experimental results show that the strain rate sensitivity increases at low temperature and it decreases at high temperature. It means that as the strain rate getting increasing, the variation of flow stress is more sensitive on the temperature. The results also indicates that the material properties of SPRC35R is more depend on the changes of strain rates and temperature than those of SPRC45E.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.106-107
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• 1997

• 대한약리학회:학술대회논문집
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• 2006.10a
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• pp.114.1-114.1
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• 2006

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.323-324
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• 2011

• Journal of Biosystems Engineering
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• v.26 no.2
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• pp.123-130
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• 2001

The research described in this paper was aimed toward improving the understanding of the interaction of tire inflation pressure and the soil-tire interface stresses. A three-directional stress transducer was developed to measure stress distribution on undertread for a tractor tire. The transducer can directly measure three-directional stresses (normal stress, tangental stress and lateral stress and lateral stress) simultaneously and has both strong structure and high sensitivity, which is not changed by the abrasion of the detecting plate. Measurements of soil-undertread interface stresses were made at tire center on undertread on a 12.4-R24 radial tractor tire opeated at three combinations of a dynamic load (11.8kN) and three inflation pressures (59kPa, 108kPa and 157kPa). These measurements showed that as inflation pressure increased, the soil-undertread interface stresses increased. The results of three stresses comparisons were shown that the peak normal stresses were considerably higher than the tangential peak stresses and the peak lateral stresses.

• Journal of the Korean Data and Information Science Society
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• v.26 no.1
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• pp.271-280
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• 2015

In this paper, the maximum likelihood estimators for parameters are derived under three step-stress accelerated life tests for Type-I hybrid censored data. The exponential distribution and the cumulative exposure model are considered based on the assumption that a log quadratic relationship exits between stress and the mean lifetime ${\theta}$. The test plan to search optimal stress change times minimizing the asymptotic variance of maximum likelihood estimators are presented. A numerical example to illustrate the proposed inferential procedures and some simulation results to investigate the sensitivity of the optimal stress change times by the guessed parameters are given.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.213-222
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• 2019

Purpose : The purpose of this study was to compare stress and psychological status between a stroke and a fracture patient's caregivers. Methods : Data was collected from September to December 2018 and participants of this study were 60 stroke and 61 fracture patient's caregivers. Stress was evaluated with the Global Assessment of Recent Stress scale-Korean Version and psychological status was measured with the Symptom check List-90-Revision. Results : The stroke patient's caregivers scored significantly higher than the fracture patient's caregivers in stress relevant to interpersonal, change in relationship, sickness or injury, financial, change/no change in routine (p<.05). The stroke patient's caregivers scored significantly higher in somatization, interpersonal sensitivity, depression, anxiety, paranoid ideation, and psychoticism than the fracture patient's caregivers (p<.05). Conclusion : It was found that the severity of mental health in the stroke patient's caregivers is necessary to develop a customized mental health improvement program for stroke patient's caregivers.

• Structural Engineering and Mechanics
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• v.59 no.3
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• pp.527-537
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• 2016

We describe a stress analysis of a single leaf flexure under torsion in which the warping effect is considered. The theoretical equations for the warping normal stress (${\sigma}_{xx}$) and shear stresses (${\tau}_{xz}$ and ${\tau}_{xy}$) are derived by applying the warping function of a rectangular cross-sectional beam and the twist angle equation that includes the warping torsion. The results are compared with those of the non-warping case and are verified using finite element analysis (FEA). A sensitivity analysis over the length, width, and thickness is performed and verified via FEA. The results show that the errors between the theory of warping stress results and the FEA results are lower than 4%. This indicates that the proposed theoretical stress analysis with warping is accurate in the torsion analysis of a single leaf flexure.

• International Journal of Reliability and Applications
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• v.18 no.2
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• pp.45-63
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• 2017

In this paper, we have formulated optimum Accelerated Life Test (ALT) plan for a parallel system with two independent components using masked data with ramp-stress loading scheme and Type-I censoring. Consider a system of two independent and non-identical components connected in parallel. Such a system fails whenever all of its components has failed. The exact component that causes the system to fail is often unknown due to cost and time constraint. For each parallel system at test, we observe its system's failure time and a set of component that includes the component actually causing the system to fail. The stress-life relationship is modelled using inverse power law, and cumulative exposure model is assumed to model the effect of changing stress. The optimal plan consists in finding out the optimum stress rate using D-optimality criterion. The method developed has been explained using a numerical example and sensitivity analysis carried out.