• Computers and Concrete
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• v.18 no.2
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• pp.201-214
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• 2016

In this paper, a multilaminate based model have been developed and presented to predict the strain hardening behavior of rock. In this multilaminate model, the stress-strain behavior of a material is obtained by integrating the mechanical response of an infinite number of predefined oriented planes passing through a material point. Essential features such as the variable deformations hypothesis and multilaminate model are discussed. The methodology to be discussed here is modeling of strains on the 13 laminates passing through a point in each loading step. Upon the presented methodology, more attention has been given to hardening in non-linear behaviour of rock in going from the peak to residual strengths. The predictions of the derived stress-strain model are compared to experimental results for marble, sandstone and dense Cambria sand. The comparisons demonstrate the ability of this model to reproduce accurately the mechanical behavior of rocks.

• Journal of Korean Home Economics Education Association
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• v.8 no.1
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• pp.59-78
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• 1996

The purpose of this study were to investigate adolescents’level of stress, and coping behavior of stress as related to socio-demographic variables. The subjects were 270 first-grade middle school students and 258 first-grade high school students in Ansan. The data were analyzed by S.A.S. Program Package, the statistical methods of Frequency, Percentage, Mean, Standard deviation, T-test, One-way Anova, DMR(Duncan’s Multiple Range Test) The results of this study were as followed：1) The general tendency of adolescents’level of stress, and coping behavior of stress were that high school students experienced more stress than middle school students and both experienced more stress in school life than in family life. 2) According to personal variable, there were differences in the grade and scholarly attainment in the low-level stress group. According to parents variables, the level of stress differed significantly according to mother’s school career and father’s occupation in the low-level-stress group. There was significant difference in accordance with mother’s occupation in the high-level-stress group. 3) The coping behavior of stress according to adolescent variables differed significantly according to grades, the monthly income of the household, mother’s level of education and the father’s occupation.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.90-100
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• 1993

This paper presents some inherent characteristics of a semi-active variable damper featuring electro-rheological (ER) fluid. The damping force of the damper can be selectively adjusted or controlled by employing electric field to the ER fluid domain. This is possible owing to the pressure drop across the piston occured by field-dependent variable yield stress of the ER fluid. This is fundamentally different than the performance of a conventional adjustable viscous damper. To demonstrate the effectiveness and superiority over the conventional one, the proposed damper is incorporated with a suspension system. A quarter car model with the suspension system is formulated and represented by a state equation. By choosing numerical values based on realistic package size, power requirements and suitable ER properties, the performance characteristics of the suspension system are obtained and evaluated in both frequency and time domains. The effects of constant electric field and on-off controlled electric field which relates to the damping force are also examined.

• Transactions of Materials Processing
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• v.15 no.9 s.90
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• pp.641-647
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• 2006

During the injection molding process an excessive packing can occur in the smaller volume cavity because of volumetric difference of the family-mold. It causes warpage by increased residual stress in the product and flesh by over packing. In this study, we used a variable-runner system for the filling balance of the cavities by changing the cross-sectional area of a runner, and confirmed the filling imbalance by temperature and pressure sensors. We carried out experiments to examine the influence of types of resins such as LDPE/ABS/PA6,6 on the filling balancing of the system, in order to help mold designers, who can easily adopt the variable-runner system to their design. We also examined filling imbalance in the system with CAE analysis.

• Transactions of Materials Processing
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• v.24 no.5
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• pp.368-374
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• 2015

Hydroforming of a non-axisymmetric thin-walled tubular component with variable cross sections was analyzed. In order to solve the sealing problem which occurred due to the thin and non-axisymmetric shape, the use of a lead patch on the punch, which had been successful in hydroforming of thin tubes, was evaluated. A lead patch was attached to the punch to solve the sealing problem, which was caused by the stress gradient in the non-axisymmetric shape. FEM and experiments were also performed to analyze these sealing problems associated with the punch shape and non-axisymmetric shape. Finally, the lead patch was attached at tube surface where intensive local strain concentration would occur to enhance the hydroformability. These methods were successfully used to fabricate non-axisymmetric thin-walled tubular component with variable cross sections that had previously failed during traditional hydroforming.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.379-384
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• 2005

Research interest on flexible body dynamics, has been increased recently. The major application areas are the auto-mobile, train, and heavy machinery. This paper attempted the dynamic analysis for the variable-gauge wheelset with a flexible body, to better understand the dynamic characteristics of the variable-gauge wheelset. In order to achieve this goal, a 3D-Virtual Mock-up model was built. The tendency of the stress and deformation for the flexible lever was investigated through component mode synthesis, contact mechanics and flexible body dynamics. This study is a pioneering work for the development of Korean type variable-gauge wheelset.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.753-759
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• 2010

The variable fatigue load is simulated in this study. The stability and the life of the material are analyzed theoretically by Ansys program. These results are successfully applied to the practical wheel to predict the prevention of fracture and the endurance. The life and the damage on the every part of the fatigue specimen can be predicted. As the available lives are compared for every loading variation, the rain flow and damage matrix results can be helpful in determining the effects of small stress cycles in any loading history. The rainbow and damage matrices illustrate the possible effects of infinite life. The safety and stability of wheel and the other practical structures according to the variable load can be estimated by using the results of this study.

• Smart Structures and Systems
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• v.21 no.2
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• pp.163-170
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• 2018

The dynamic response of a finite length thermo-piezoelectric rod with variable material properties is investigated in the context of the fractional order theory of thermoelasticity. The rod is subjected to a moving heat source and fixed at both ends. The governing equations are formulated and then solved by means of Laplace transform together with its numerical inversion. The results of the non-dimensional temperature, displacement and stress in the rod are obtained and illustrated graphically. Meanwhile, the effects of the fractional order parameter, the velocity of heat source and the variable material properties on the variations of the considered variables are presented, and the results show that they significantly influence the variations of the considered variables.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.661-665
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• 2005

The muffler reducing the exhaust noise and vibration from the engine influence on the engine performance. Recently the semi-active muffler was developed and adopted to the actual use in consideration of the cost and technical side for noise and vibration. This study is about the recently developed semi-active muffler. This paper attempt to analyze the dynamic stress field on the gate plate by using the finite element methods. According to the analysis of the Exhaust Variable Valve, its spring has the most influence on its operation compare with effects of other components. The design parameters of the Exhaust Variable Valve such as the spring displacement, diameter, coil number, free angle and so forth were used.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.2 no.2
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• pp.141-150
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• 2007

Objectives : The purpose of this study was to investigate the correlation of stress and meridian muscle electrography in Korean adult males. Methods : Sixty-nine volunteers suffering from stress participated in this study. Physical examination, stress survey and meridian muscle electrography were performed. Each variable was compared with each other by correlation analysis. Results : Correlation between stress response inventory and fatigue of trapezius muscle right upper portion was statistically significant. In relationship between sub scales of stress response inventory and meridian muscle electrography, fatigue of trapezius muscle right upper portion was statistically significant with tension, depression, and frustration. Contraction power of left sternocleidomastoid muscle was significant with somatization and others were not significant. Conclusions : In Korean adult males, trapezius muscle shows more fatigue under more stress. This suggests that stress influences muscle fatigue. Although meridian muscle electrography is not a typical method for the evaluation of pain nor stress, this is referential method to clinical evaluation of painful shoulder caused stress.