• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2071-2081
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• 1995

In order to examine the effects of yield stress, tensile strength and thickness on the buckling behavior during bending of pipes, the nonlinear finite element analysis of the 3-point bending tests was carried out using the commercial software (ABAQUS) under the condition of L4(2$^{3}$) performed according to the designed condition. Form the analysis of simulation results, it was found that yield stress and thickness were the major factors on buckling load at pipe bending and tensile strength gave little influence because the plastic strain and plastic zone are small. For the punch displacement to the occurrence of buckling, thickness is a major factor and yield stress and tensile strength are the minor factors.

• Transactions of Materials Processing
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• v.33 no.3
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• pp.200-207
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• 2024

In this study, we developed a semi-analytical approach for the numerical analysis of residual stress in oxide scales formed on hot-rolled steels. The oxide scale, formed during the hot rolling process, experiences complex interactions due to thermal and mechanical influences, significantly affecting the material's integrity and performance. Our research focuses on integrating various stress components such as thermal stress, growth stress, and creep behavior to predict the residual stress within the oxide layer. The semi-analytical method combines analytical expressions for each stress component with numerical integration to account for their cumulative effects. Validation through instrumented indentation tests confirms the reliability of our model, which considers thermal expansion coefficient (CTE) differences, scale growth, and creep-induced stress relaxation. Our findings indicate that thermal stress resulting from CTE differences significantly impacts the overall residual stress, with growth stress contributing a compressive component during cooling, and creep behavior playing a minor role in stress relaxation. This comprehensive approach enhances the accuracy of residual stress prediction, facilitating the optimization of material design and processing conditions for hot-rolled steel products.

• Journal of the Korean earth science society
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• v.29 no.3
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• pp.255-262
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• 2008

Late Cretaceous to early Tertiary paleostress was evaluated by analyzing the healed microcracks in the Cretaceous granite of the Goheung area, south Korea. Healed microcracks in five granite samples (GH-1, GH-3, GH-4, GH-5, GH-8) were investigated and measured according to direction. The directions of maximum horizontal principal stress in GH-1, GH-3, and GH-4 are dominantly $N60^{\circ}W\;and\;N70^{\circ}E,\;N20^{\circ}W\;and\;N50^{\circ}W$, while minor directions are N-S and $N30^{\circ}E$. In GH-5 and GH-8, $N40^{\circ}E\;and\;N10^{\circ}E$ are the most dominant directions, while $N40^{\circ}W$ is the minor direction. Thus overall, the most dominant directions of healed microcracks in the study area are oriented $N60^{\circ}W$, while minor directions are oriented $N20^{\circ}W,\;N20^{\circ}E\;and\;N70^{\circ}E$, essentially NE. Combining the paleostress results of this study with other studies, the direction of the maximum horizontal principal stress in the study area during the late Cretaceous to the early Tertiary should perhaps be changed WNW to NE. The reason for this is thought to be the complex tectonic movements which occurred in northeast Asia at that time.

• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.361-373
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• 2020

The purpose of this study was to meta-analyze the stress intervention program applied to patients with hemodialysis in Korea to confirm the effectiveness of the stress intervention program and to identify the characteristics and trends of the stress intervention method. A total of 10 studies were selected, and Quality Assessment tool was used MINORS and the data was analyzed using Comprehensive Meta Analysis Version 3.0 and Review manager version 5.3 The Quality Assessment score of studies was 21.2 points, and the effect size on the psychological stress was medium(g=-.72), and the effect size on cortisol of the physiological stress was also medium(g=-.52). Subgroup analysis showed that Music therapy and aromatherapy, individual providing, over 60 minutes per session and total of 10-20 times were more effectively reduced stress. Findings of this meta-analysis would be helpful for health professionals to provide more effective stress intervention program. Further randomized controlled trials of stress intervention program for patients with hemodialysis are more needed.

• Journal of Oriental Neuropsychiatry
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• v.18 no.3
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• pp.249-260
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• 2007

Recently, usual minor stress is getting more important in somatization disorder. This study is a clinical report of a patient with somatization disorder induced by stress treated with typical orintal medical therapy reinforcing the weakness of heart and gall blaader(Herb-med, acupunture, etc.) in combination with EFT. STAI, BDI were compared between before and after treatment. The results show the typical onntal medical therapy reinforcing the weakness of heart and gall blaader in combination with EFT is efficient in the treatment of Somatization disorder.

• Tunnel and Underground Space
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• v.6 no.2
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• pp.101-121
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• 1996

The thermomechanical characteristics of rocks such as temperature dependency of strength and deformation were experimentally investigated using Iksan granite, Cheonan tonalite and Chung-ju dolomite for proper design and stability analysis of underground structures subjected to temperature changes. For the temperature below critical threshold temperature $T_c$, the variation of uniaxial compressive strength, Young's modulus, Brazilian tensile strength and cohesion with temperature were slightly different for each rock type, but these mechanical properties decreased at the temperatures above $T_c$ by the effect of thermal cracking. Tensile strength was most affected by $T_c$, and uniaxial compressive strength was least affected by $T_c$. To the temperature of 20$0^{\circ}C$ with the confining prressure to 150 kg/$\textrm{cm}^2$, failure limit on principal stress plane and failure envelope on $\sigma$-$\tau$ plane of Iksan granite were continuously lowered with increasing temperature but those of Cheonan tonalite and Chung-ju dolomite showed different characteristics depending on minor principal stress on principal stress plane and normal stress on $\sigma$-$\tau$ plane. The reason for this appeared to be the effect of rock characteristics and confining pressure. Young's modulus was also temperature and pressure dependent, but the variation of Young's modulus was about 10%, which was small compared to the variation of compressive strength. In general, Young's modulus increased with increasing confining pressure and increased or decreased with increasing temperature to 20$0^{\circ}C$ depending on the rock type.

• Journal of Korean Orthopaedic Sports Medicine
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• v.9 no.2
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• pp.114-120
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• 2010

Anterior tibial diaphyseal stress fracture have a propensity for delayed union or nonunion and have risk of complete fracture after minor trauma. So, careful evaluation and optimal management are mandatory to succeed in treatment. It is also important to decide the point of time of return to full activity. We report experience of treatment for complete fracture of the delayed union of anterior tibial diaphyseal stress fracture as an athletic injury.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.350-355
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• 2005

This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR Product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant Properties; the minor loop property and the wiping-out property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.127-139
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• 1999

Two studies were conducted to examine the relationship between self-efficacy beliefs and industrial accidents. In the preliminary study, focus group interviews were conducted with employees working in manufacturing and construction sector, safety managers, and government officials to understand factors that were associated with industrial accidents. Based on interviews, a questionnaire survey was constructed to assess individual factors (such as self-efficacy beliefs, following safety procedures, life-satisfaction, and stress) that were identified as affecting industrial accidents (such as minor and major accident rates). The questionnaire were administered to a total of 917 respondents (542 employees working in the manufacturing and construction sector, 210 safety managers, and 165 government employee officials overseeing government regulations). The result indicated that three subscales of self-efficacy for employees (self-regulation, enlisting social support, and controlling the environment) were negatively correlated with the company's industrial accident rates. Moreover, those employees with higher self-efficacy were more likely to follow safety procedures and had higher life-satisfaction and lower stress levels. For safety managers, the self-efficacy beliefs were positively correlated with better implementation and higher effectiveness of the educational programs and negatively correlated with their company's accident rates.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.509-518
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• 1995

A study for the flame stability and the combustion characteristics of coaxial diffusion flame was conducted. The fuel employed was natural gas. The experimental variables were rim thickness of fuel tube, blockage ratio of the outer diameter of fuel tube to the inner diameter of air tube, and momentum ratio of fuel to air. It was consequently found that the stability in the neighborhood of the fuel rim depended on the rim thickness, especially in the case of above 3 mm, and that the stable region of the flame extended remarkably due to the formation of recirculation zone above rim. The effect of the blockage ratio on the flame stability was found to be minor in the case of above 3 mm of rim thickness. Between the momentum ratio 2 and 3, the stable flame zone was widely established as well good combustion. With increasing the fuel-air momentum ratio, axial velocity, turbulence intensity, and Reynolds stress increased.