• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.31-38
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• 1999

Square cups have been drawn to 20mm~60mm in depth and displacements and strains have been analysed by FEM and experiment. Displacements and strains on the corner flange of square cups have been compared with those of cylindrical cups. The results have shown that shear strains take place on corner flanges of square cups, it is necessary to adopt effective strain for comparing of stains and the effective strains on the corner flange in square cups are smaller than those in cylindrical ones.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.88-94
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• 2012

An axle drive shaft with double joint shaft, cross kit and yoke has an important role by transferring power and changing steering angle between axle and wheel in power train system. It has been used widely in the heavy machinery requiring a high reliability in the power train system. At fatigue failures of the axle drive shaft with the long span, a relatively high stress concentration at a snap ring groove on the drive shaft brings to significant fatigue damages under repeated loading condition. As Peterson's suggestions on this study, a relief groove in the vicinity of the snap ring groove is applied by decreasing the stress concentration and improving the fatigue life of axle drive shaft. By using FEM analysis, the decreasing effect of the stress concentration and extended fatigue life are due to the change of design parameters related with size and location of the relief groove. The relief groove with the design parameters such as d/b=2.0 and r/h=1.2 enables to decrease the stress concentration of 22.3% and increase the fatigue life more than 3 times by comparing with no relief groove application.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.6
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• pp.59-66
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• 2001

Fatigue strength of the welding structure is governed by the residual stress at the weldment toe and static tensile overloads were known as relieving the residual stresses. In this study, static tensile overloads were applied to the welding structures which caused the relief of residual stresses. The amount of residual stress relief was found as proportional to the change of fatigue limit at the given conditions. Based on the fact of the proportionality between the change of fatigue limit and that of residual stress, simple measurement technique is proposed. Modified stress-life curves base on proposed technique gave good agreement with test results.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.734-741
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• 2008

At-rest and active earth pressure in plane strain condition have been applied to the design of cylindrical retaining walls. But many researchers have indicated that the earth pressure on the cylindrical retaining walls would be smaller than in plane strain condition due to wall deformation and stress relief. In this paper, the distribution of earth pressure acting on diaphragm wall of a shaft in dry sand was predicted by using the convergence confinement method and model test was performed to verify the estimated values. Test results showed that the earth pressure acting on the diaphragm wall of a shaft was expected to be 1.1~1.5 times larger than active earth pressure of plane strain condition and 0.7~0.9 times less than at-rest earth pressure.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.4
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• pp.161-172
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• 2020

The tensile property of A5082 and A6060 aluminium wrought alloys was investigated, in terms of the strain rate sensitivity on alloy conditions by heat treatment and bake hardenability on pre-strain prior to strain ageing. The tensile test was carried out in a range of strain rate of 4.17 × 10^-5 s^-1 ~ 4.17 × 10^-5 s^-1 in room temperature and the nominal range of pre-strain was 3.0 ~ 10.5%. The tensile deformation of A5082 alloys is characterized as typical case of dynamic strain ageing with negative strain rate sensitivity for all conditions, and the tensile strength indicates a similar level regardless of alloy conditions, except only in full annealed condition. The stress-relief annealing on A6060 alloys can induce practical decrease in strength level of over approximately 100 MPa without any ductility loss, compared to as-rolled condition, while a full annealed and aged condition leads remarkable strengthening effect with the decrease of tensile elongation. Additionally, the bake hardenability of A5082 alloy by strain ageing indicates a negative dependence upon the increase of pre-strain, while A6060 alloy exhibits a positive sign even in low level relatively compared with conventional SPCC.

• Journal of Fashion Business
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• v.28 no.2
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• pp.109-124
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• 2024

The aim of this paper is to design and evaluate calf braces that are equipped with Electrical Muscle Stimulation (EMS) modules. These braces are intended to alleviate calf pain in PARA Taekwondo athletes. The paper also seeks to assess the effects of different textile electrode designs. PARA Taekwondo participants are at a heightened risk of injuries and pain due to the nature of this exercise, which is designed for individuals with disabilities. Additionally, there is a significant risk of strain on the lower limb muscles in PARA Taekwondo compared to regular Taekwondo. To address this issue, calf taping methods are commonly used. In this study, we develop calf EMS protective gear and aim to examine the effects of different textile electrode designs inspired by taping methods. We evaluate the differences in the effects of three different textile electrode designs through visual analog scale (VAS) and range of motion (ROM) measurements. The results show that EMS protective gear has the potential to reduce calf pain among PARA Taekwondo athletes, with electrode designs inspired by kinesiology taping providing the most effective pain relief. This research suggests that these findings may be applicable to other sports disciplines, body areas, and everyday pain relief scenarios.

• Journal of Welding and Joining
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• v.22 no.2
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• pp.33-37
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• 2004

Since the preflex beam is fabricated by welding, the pre-compressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. For this reason distribution of welding residual stresses must be analyzed accurately and welding residual stresses should be relieved during the fabrication. In this study strain history, displacement of beam and re-distributed welding residual stresses by different loading conditions are measured and compared to choose more appropriate preflex condition.

• Proceedings of the Materials Research Society of Korea Conference
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• 2004.05a
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• pp.73-73
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• 2004

• Journal of Welding and Joining
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• v.14 no.3
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• pp.48-57
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• 1996

A study was made to examine the characteristics of base metal and stress relief cracking(SRC) of heat affected zone(HAZ) for HY-100 and Cu-bearing HSLA-100 steels. The Gleeble thermal/mechanical simulator was used to simulate the SRC/HAZ. The details of mechanical properties of base plate and SRC tested specimens were studied by impact test, optical microscopy and scanning electron microscopy. The specimens were aged at $650^{\circ}C$ for HSLA-100 steel and at $660^{\circ}C$ for HY-100 steel and thermal cycled from $1350^{\circ}C$ to $25^{\circ}C$ with a cooling time of $\Delta$t_${800^{circ}C/500^{circ}C}$=21sec. corresponds to the heat input of 30kJ/cm. The thermal cycled specimens were stressed to a predetermined level of 248~600MPa and then reheated to the stress relief temperatures of $570~620^{\circ}C$. The time to failure$(t_f)$ at a given stress level was used as a measure of SRC susceptibility. The strength, elongation and impact toughness of base plate were greater in HSLA-100 steel than in HY-100 steel. The time to failure was decreased with increasing temperature and/or stress. HSLA-100 steel was more susceptible to stress relief cracking than HY-100 steel under same conditions. It is thought to be resulted from the precipitation of $\varepsilon$-Cu phase by dynamic self diffusion of solute atoms. By the precipitation of $\varepsilon$-Cu phase, the differential strengthening of grain interior relative to grain boundary may be greater in the Cu-bearing HSLA-100 steel than in HY-100 steel. Therefore, greater strain concentration at grain boundary of HSLA-100 steel results in the increased SRC susceptibility. The activation energies for SRC of HSLA-100 steel are 103.9kcal/mal for 387MPa and 87.6kcal/mol for 437MPa and that of HY-100 steel is 129.2kcal/mol for 437MPa.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.14-21
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• 1999

Trapezoid cups and square ones have been deep-drawn to 45mm in depth. Displacements and strains have been analysed by FEM and experiment. Strains and effective strains in the corner flanges of trapezoid cups have been compared with those in square cups. The results have shown that because of shear strains on the corner flange, it is necessary to adopt effective strain for comparing strains, mean vale of effective strains in the corner flange with a corner angle of 72 degrees is narly equal to those with a corner angle of a right angle and mean value of effective strains with a corner angle of 102 degrees is smaller than those with a corner angle of a right angle.