• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.50-52
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• 2007

Large size forged parts usually were made by hot open die forging because of the die cost, high applied load and small manufacturing quantities. Cast ingots were used in open die forging and the ingots almost included the cavities in its inside. Therefore, one of the aims for forging processes is to close and remove the cavities. However, its criteria were well not defined since the studies have many difficulties to investigate the cavity behaviors because of its large size. In this study, the cavity closure behavior was investigated by experimental and FE analysis. The FEM analysis is performed to investigate the overlap defect of cast ingots during free forging stage. The measured flow stress data were used to simulate the forging process of cast ingot using the practical material properties. Also the analysis of cavity closure is performed by using the $DEFORM^{TM}$-3D. The calculated results of cavity closure behavior are compared with the measured results before and after forging, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the cavity closure can be investigated by the comparison between practical experiment and numerical analysis.

• Journal of Aerospace System Engineering
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• v.14 no.6
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• pp.58-67
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• 2020

In this study, finite element fatigue analysis combined with a fatigue correlation factor is proposed to predict the bending fatigue life of a gear in an electro-mechanical aircraft actuator. First, stress-life curves are obtained for the gear material via a round bar fatigue test. Subsequently, stochastic stress-life (P-S-N) curves are derived for 50% and 1% failure probabilities, separately. The curves are applied to the fatigue analysis model of a single gear tooth, and the effect of the fatigue correction factor is analyzed. The analytical P-S-N curves reflecting the fatigue correction factor matched the experimental data. This shows that the analytical fatigue life is reliable and that the analysis technique is effective.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.3
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• pp.26-31
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• 2015

The domestic and foreign specifications presented the effective width based on flange length to width ratio only. The existing paper on the effective width grasped of the effect of span, load type and cross-section properties, but localized steel bridges. Recently, The studies are going on in progress for the application of fiber reinforced composite material in construction field. Therefore, it is required to optimum design that have a good grasp the deformation characteristic of the displacements and stresses distribution and predict variation of the effective width for serviceability loading. This research addresses the effective width of all composite material box girder bridges using the finite element method. The characteristics of the effective width of composite structures may vary according to several causes, e.g., change of fibers, aspect, etc. Parametric studies were conducted to determine the effective width on the stress elastic analysis of all composite materials box bridges, with interesting observations. The various results through numerical analysis will present an important document for construct all composite material bridges.

• Journal of Ginseng Research
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• v.47 no.6
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• pp.766-772
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• 2023

Background: Korean Red Ginseng (KRG) is an effective anti-stress treatment. In this study, we investigated the therapeutic potential effects of KRG on relieving stress in a general population using transcriptome analysis. Methods: We conducted an 8-week clinical pilot study on 90 healthy men who reported stress. The study was completed by 43 participants in the KRG group and 44 participants in the placebo group. Participants were randomized 1:1 to the KRG and placebo groups. We evaluated the stress by stress response inventory (SRI) at baseline and 8 weeks. The main outcomes were changes in the levels of neurotransmitters (NTs) and NT-related gene expression. NTs were analyzed using automated (GC) content, and levels of gene expression were measured by reads per kilobase of transcript per million mapped reads (RPKM). Results: The KRG group showed significantly preserved epinephrine decrease compared with placebo group at 8 weeks (changes in epinephrine, KRG vs. placebo; -1623.2 ± 46101.5 vs. -35116.3 ± 86288.2, p = 0012). Among subjects who higher SRI score, meaning stress increased compared to baseline, the KRG group showed a smaller decrease in serotonin than the placebo group (changes in serotonin, KRG vs. placebo; -2627.5 ± 5859.1 vs, -8087.4 ± 7162.4, p = 0.005) and a smaller increase in cortisol than the placebo group (changes in cortisol, KRG vs. placebo; 1912.7 ± 10097.75 vs. 8046.2 ± 8050.6 , p = 0.019) in subgroup analysis. Transcriptome findings indicated that KRG intake affects gene expression related with metabolism of choline, adrenalin, and monoamine. Conclusion: These findings suggest that KRG has beneficial effects on the amelioration of stress response in NTs, and this effect is more prominent in stressful situations. Further clinical studies are required to confirm the anti-stress effect of KRG.

• Korean Journal of Occupational Health Nursing
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• v.22 no.3
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• pp.257-265
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• 2013

Purpose: This study aimed to investigate the job stress level of call center workers and figure out its relation with cognitive emotion regulation strategies as a cognitive coping strategy. Methods: Data collection was conducted on 985 call center workers, working for K companies in Korea. ANOVA, t-test, Scheffe's test and multiple regression have been conducted for the data analysis using SAS 9.0 software. Results: The total job stress score of subjects ranges $Q_{25{\sim}49}$ (the lower 50%) whereas the score of job demand and job control ranges $Q_{50{\sim}74}$ (the upper 50%), and its sectional job stress level is high. Since job stress is the major factor affecting cognitive emotion regulation strategies, it is shown that when the job stress score gets higher, the score of positive cognitive emotion regulation strategies gets decreased but the score of negative cognitive emotion regulation strategies, increased. Conclusion: Based on the results of this study, it is necessary to develop and apply an effective stress easing method for call center workers which reduces negative cognitive emotion regulation strategies and increases positive ones.

• Fire Science and Engineering
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• v.26 no.5
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• pp.28-34
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• 2012

Effective for the operation of fire department management of occupational stress than what organizational members perceive and to identify factors that would cause job stress. Dysfunction caused by job stress or minimize that by eliminating the stress factor that can enhance organizational effectiveness research is needed. The results of the study the impact on job stress of firefighters of the psychological environment of the most influential factor is the variable. Next, organizational culture, physical environment, orderly, and administration and human relations were not significant statistically.

• The Journal of Korean Society for School & Community Health Education
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• v.20 no.3
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• pp.43-52
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• 2019

Objectives: This study aims to understand the effects of job stress and emotional labor on perceptive health status of dental hygienist's. And provide basic data by for establishing the plan for the effective management of job stress and emotional labor and the promotion of health. Methods: Self-evaluation questionnaires were surveyed for 441 dental hygienist's who agreed to participate in the survey, using questionnaires used in the preceding study were modified and complemented. We analyzed the data with frequency analysis, descriptive statistics, t-test, chi-square test와 ANOVA, Spearman correlation coefficient by using IBM SPSS Statistics 21.0 (IBM Co., Armonk, NY, USA). The significance level for significance was set at 0.05. Results: health status were job stress, emotional labor significant negative correlation. The factors having significant effects on health problem were physical health status, the job culture of job stress, lack of job autonomy, organizational instability, and workplace culture. In addition, social health status was affected by emotional expressionism, relationship conflict, organizational instability, organizational system, and workplace culture. Conclusion: Recognizing the importance of the management of job stress and emotional labor in the working environment to dental clinic and hospital managers and managerial dental hygienists, a dental hygienist health promotion intervention program is needed to mitigate and cope with job stress and emotional labor.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1794-1804
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• 1993

The thermal stress intensity factors for interface cracks of Griffith and symmetric lip cusp types under vertical uniform heat flow in a finite body are calculated by boundary element method. The boundary conditions on the crack surfaces are insulated or fixed to constant temperature. The relationship between the stress intensity factors and the displacements on the nodal point of a crack tip element is derived. The numerical values of the thermal stress intensity factors for interface Griffith crack in an infinite body and for symmetric lip cusp crack in a finite and homogeneous body are compared with the previous solutions. The thermal stress intensity factors for symmetric lip cusp interface crack in a finite body are calculated with respect to various effective crack lengths, configuration parameters, material property ratios and the thermal boundary conditions on the crack surfaces. Under the same outer boundary conditions, there are no appreciable differences in the distribution of thermal stress intensity factors with respect to each material properties. But the effect of crack surface thermal boundary conditions on the thermal stress intensity factors is considerable.

• The Korean Journal of Health Service Management
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• v.13 no.2
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• pp.55-66
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• 2019

Objectives: The objective of the present study was to investigate whether gender mederates the mediating effect of job burnout on the relationship between role stress and depression among medical doctors in Local clinics in South Korea. Methods: Questionnaires that assess role stress, job burnout, and depression were administered to. 265 medical doctors who worke in local clinics in Seoul, Busan, Daejeon, and Gyeonggi provinces. Data analysis was conducted using the PROCESS macro in Statistical Package for the Social Sciences(SPSS). Results: Job burnout mediated the relationship between role stress and depression. Further, gender moderated the relationship between role stress and job burnout. Finally, gender moderated the mediating effect of job burnout on the relationship between role stress and depression. Conclusions: On the basis of the emergent findings, effective coping strategies that can alleviate role stress are articulated. However, the findings also suggest that the selection of a suitable intervention must be based on the gender of the medical doctor.

• The Journal of the Korea Contents Association
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• v.14 no.3
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• pp.223-231
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• 2014

This study aims to identify job stress of firemen and the relations between their job stress, depression and fatigue, targeting firemen who are working for local fire stations. We interviewed the subjects using a short-answer type questionnaire or a online questionnaire. The data collected were analysed with a use of SPSS WIN 15.0 for confidence analysis, correlation analysis, step-by-step multi-regression analysis, and covariance structure analysis(CSA). This study result tasks and emotional stress had a direct effect on depression and fatigue. Therefore, this study suggests that governmental management should be provided for firemen that are classified as a high-risk group in occupational characteristics. Above all, the causes of stress should be diagnosed, its management goals should be set, and effective intervention programs should be provided.