• Title/Summary/Keyword: Stress effect

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Molecular dynamics study of Al solute-dislocation interactions in Mg alloys

  • Shen, Luming
    • Interaction and multiscale mechanics
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    • v.6 no.2
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    • pp.127-136
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    • 2013
  • In this study, atomistic simulations are performed to study the effect of Al solute on the behaviour of edge dislocation in Mg alloys. After the dissociation of an Mg basal edge dislocation into two Shockley partials using molecular mechanics, the interaction between the dislocation and Al solute at different temperatures is studied using molecular dynamics. It appears from the simulations that the critical shear stress increases with the Al solute concentration. Comparing with the solute effect at T = 0 K, however, the critical shear stress at a finite temperature is lower since the kinetic energy of the atoms can help the dislocation conquer the energy barriers created by the Al atoms. The velocity of the edge dislocation decreases as the Al concentration increases when the external shear stress is relatively small regardless of temperature. The Al concentration effect on the dislocation velocity is not significant at very high shear stress level when the solute concentration is below 4.0 at%. Drag coefficient B increases with the Al concentration when the stress to temperature ratio is below 0.3 MPa/K, although the effect is more significant at low temperatures.

The Effects of Depression and Stress on College Life Adjustment of Ophthalmic Optics Students

  • Cho, Seonahr;Kwak, Jinkyu
    • International Journal of Advanced Culture Technology
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    • v.7 no.4
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    • pp.14-22
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    • 2019
  • This study is intended to look into the effects of depression and stress on college life adjustment of ophthalmic optics students. To achieve this, a survey was empirically carried out to 142 male and female students majoring in ophthalmic optics at colleges in Gangwon-do. The findings are as follows: Depression had a significant effect on academic adjustment and social adjustment, but no significant effect on emotional adjustment and college satisfaction. Stress also had a significant effect on academic adjustment, but no significant effect on social adjustment, emotional adjustment and college satisfaction. The above results showed that depression and stress were major factors affecting academic and social adjustments, and academic adjustment, respectively. Which means that depression restricted the activities of academic adjustment and social adjustment, and did not have a close relationship with psychological mechanisms - emotional adjustment and college life satisfaction. Stress also had a significant effect on academic adjustment, but did not have a direct relationship with social adjustment, emotional adjustment and college satisfaction.

Effect of Bunsimgieumgagambang on the Stress Due to the Maternal Separation in Rats (분심기음가감방(分心氣飮加減方)이 모성분리(母性分離) stress 백서(白鼠)에 미치는 영향)

  • Kim Ki-Bong;Kim Jang-Hyun;Chang Gyu-Tae
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.19 no.5
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    • pp.1303-1310
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    • 2005
  • This study was performed to investigate the effect of Bunsimgieumgagam on the stress due to the maternal separation in rat. In this study, we researched in 'the behavioral observation', 'the changes of body weight', 'quantitative analysis of the number of BrdU-positive cells per section in dentate gyrus of hippocampus', 'free radical scavenging assay' and 'MTT-based cytotoxicity assay of SK-N-SH cell line', in order to figure out the effect on which Bunsimgieumgagam has the increase of neuron in dentate gyrus of hippocampus damaged by the stress due to the maternal separation. In the behavioral Observation, Bunsimgieumgagam was also efficacious against the decline of one's behavior and anorexia derived from the stress by the maternal separation. In the change of body weight, it showed that the Bunsimgieumgagam is effective in the recovery of weight loss caused by heavy stress(p<0.05). Also, Bunsimgieumgagam had an increasing effect, which is similar to a normal state, on DG's neuron in hippocampus (P<0.001). In free radical scavenging assay, Bunsimgieumgagam had a superior free radical scavenging effect. And it showed a significant result with the high cell proliferation effect in MTT-based cytotoxicity assay(P<0.01, p<0.001) This result suggest that Bunsimgieumgagam has an anti-stress effect and a proliferation effect of neuron in dentate gyrus of hippocampus, and it shows the potential of Bunsimgieumgagam in the treatment for the various disorders derived from children's stress.

A Rhythmic Effect of Tone in English (영어 억양의 리듬효과)

  • Lee, Joo-Kyeong;Kang, Sun-Mi
    • Speech Sciences
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    • v.10 no.2
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    • pp.303-318
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    • 2003
  • This paper attempts to investigate the tonal implementations of English stress clash, arguing that a preceding stress shifts leftward when two lexical stresses conflict across word boundaries or that H* and L* pitch accents are alternatively manifested on the stressed syllables, establishing intonational peak and valley contours. We claim that the H*/L* alternation might be a tonal strategy to avoid stress clash, and that pitch could be solely manipulated to display a rhythmic effect with maintaining lexical stress. In the experiment, we examined two-word combinations whose boundaries involve stress clash, and divided them into two categories. One has the preceding words involving a heavy syllable ahead of stress to guarantee the place for a shifting stress and the other, a light syllable, in which case stress shift is completely prevented. We analyzed the distribution of pitch accents in the word combinations, focusing on the pitch configurations in the cases where stress should not be shifted. Results show that approximately 50% of the stimuli show stress shift in the heavy syllable combinations of the preceding words; the preceding stress is moved leftward within the word. The other 50% and the light syllable combinations show various pitch accents patterns; H* and L* alternation, deaccentuation of either stressed syllable, or L-insertion between two H* pitch accents, etc. We interpret this as a rhythmic effect of tone to avoid stress clash and suggest that a true stress clash would be confined into cases without H*/L* contours.

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Traffic-load-induced dynamic stress accumulation in subgrade and subsoil using small scale model tests

  • Tang, Lian Sheng;Chen, Hao Kun;Sun, Yin Lei;Zhang, Qing Hua;Liao, Hua Rong
    • Geomechanics and Engineering
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    • v.16 no.2
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    • pp.113-124
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    • 2018
  • Under repeated loading, the residual stresses within the subgrade and subsoil can accelerate the deformation of the road structures. In this paper, a series of laboratory cyclic loading model tests and small-scale model tests were conducted to investigate the dynamic stress response within soils under different loading conditions. The experimental results showed that a dynamic stress accumulation effect occurred if the soil showed cumulative deformation: (1) the residual stress increased and accumulated with an increasing number of loading cycles, and (2) the residual stress was superimposed on the stress response of the subsequent loading cycles, inducing a greater peak stress response. There are two conditions that must be met for the dynamic stress accumulation effect to occur. A threshold state exists only if the external load exceeds the cyclic threshold stress. Then, the stress accumulation effect occurs. A higher loading frequency results in a higher rate of increase for the residual stress. In addition to the superposition of the increasing residual stress, soil densification might contribute to the increasing peak stress during cyclic loading. An increase in soil stiffness and a decrease in dissipative energy induce a greater stress transmission within the material.

The Mediator Effect of Coping Strategies in the Relationship between Care Givers' Job Stress and Burnout (요양보호사의 직무스트레스와 소진과의 관계에서 스트레스 대처방식의 매개효과)

  • Moon, Hee
    • The Korean Journal of Community Living Science
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    • v.21 no.3
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    • pp.341-350
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    • 2010
  • The purpose of this study was to identify the level of care givers' job stress, burn-out and stress coping strategies and to determine the mediator effect of coping strategies in the relationship between job stress and burnout. The research subjects were 193 care givers for the elderly in Jeollanamdo. The data analysis was performed by using SPSS Win 17.0. The results of this study were as follows; The level of care givers' job stress which they perceived was 2.68 points in a scale of 5 points, stress coping strategies was 2.39 points in a scale of 4 points, and the degree of burnout was 2.27 points in a scale of 5 points. There was a positive correlation between the care givers' job stress and burnout. There was a negative correlation between the job stress and stress coping strategies. There was a positive correlation between the stress coping strategies and burnout. And the stress coping strategies showed mediating effects between the care givers' job stress and burnout. Accordingly, we found that stress coping strategies had an mediating effect on care givers' burnout and various coping strategies were related to the burnout.

Effect of Incivility Experienced by Clinical Nurses on Job Stress and the Moderating Effect of Self-efficacy (병원간호사가 경험하는 무례함이 직무 스트레스에 미치는 영향과 자기효능감의 조절효과)

  • Kim, Song Yi;Yoon, Sook Hee
    • Journal of Korean Academy of Nursing Administration
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    • v.23 no.1
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    • pp.8-17
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    • 2017
  • Purpose: The aim of this study was to analyze the effects of incivility experienced by clinical nurses on their job stress, and to identify the moderating effects of self-efficacy on the relationship between job stress and incivility. Methods: A structured self-report questionnaire was used to measure job stress, incivility and self-efficacy. Data were collected from 140 nurses currently working in three general hospitals of more than 300 beds. Data were analyzed using descriptive statistics, ANOVA, Scheffétest, Pearson correlation coefficient, hierarchical multiple linear regression with the SPSS Version 19.0 program. Results: Incivility from supervisors, patients and patients' families showed a significant effect on job stress and self-efficacy had an effect on incivility from patients and patients' families and also incivility from doctors and job stress. These variables have total explanatory power of 46.6% on job stress. Conclusion: The results indicate a need to recognize the seriousness and damage of incivility in order to reduce hospital nurses' job stress and to awaken nurses to the relationship of stress and incivility and establish institutional programs to combat incivility. Moreover, there is also a need to improve self-efficacy on the ward through hospital education and coaching.

The Effect of Job Stress on Work Impairment (직무스트레스가 직무손실에 미치는 영향)

  • Lee, Young-Mi
    • Korean Journal of Occupational Health Nursing
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    • v.17 no.1
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    • pp.55-63
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    • 2008
  • Purpose: The purpose of this paper is to analyze the effect of job stress on work impairment. Method: 354 workers' data from Seoul and the Gyeonggi area were collected between February 1 and March 30 2006 by structured questionnaire. The questionnaire was meant to determine demographic data, job stress, and work impairment questionnaire. Data analyzed by SPSS 12.0 and AMOS 5.0 program. Results: Job stress was ranked job demand, insufficient job control, organizational system, lack of reward, job insecurity, interpersonal conflict, and occupational climate. The work impairment of completing work was increased when the stress of insufficient job control, lack of reward, job insecurity, and occupational climate were increasing. The work impairment of avoiding distraction was increased when the stress of job demand, insufficient job control, organizational system, lack of reward, job insecurity, and occupational climate were increasing. The stress of job demand, lack of reward, job insecurity, and occupational climate had an effect on avoiding distraction. The stress of lack of reward and occupational climate had an effect on completing work. Conclusion: If employers manage job stress of job demand, lack of reward, job insecurity, and occupational climate, their business will benefit.

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Mediating Effect of Stress Coping Method in the Relationship Between Covid-19 Stress and Academic Burnout of College Students (대학생의 Covid-19 스트레스와 학업소진의 관계에서 스트레스 대처방식의 매개)

  • Bo Kyung, Hong
    • The Journal of Korean Society for School & Community Health Education
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    • v.23 no.4
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    • pp.1-15
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    • 2022
  • Objectives: The purpose of this study was to examine the mediating effect of Stress coping method in the relationship between Covid-19 stress and academic burnout of university students in the long-lasting Covid-19 situation. Methods: The subjects of this study were 323 college students and data were collected by on-line questionnaire survey. The collected data was analyzed using SPSS 23.0 and t-test, ANOVA, multiple linear regression analysis were conducted. Also mediation analysis was performed according to the Baron & Kenny method. Results: The results were as follows. First, students with high Covid-19 stress had high academic burnout by regression analysis. Second, in the stress coping method, the active coping method lowered academic burnout, and the passive coping method increased academic burnout. Third, the active coping method showed a partial mediating effect in the relationship between Covid-19 stress and the academic burnout(p<.01). Conclusions: In order to help college students cope with academic burnout caused by Covid-19 stress, it is recommended to guide students to use active coping method through counseling and education. Ultimately, it is necessary to support students to use various coping methods according to their situation appropriately.

Stress Analysis of Hollow Cylinder with Inner Cracks Subjected to Torsion Moment (내부크랙을 가지며 비틀림모멘트를 받는 중공축의 응력해석)

  • 이종선
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1998.03a
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    • pp.123-128
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    • 1998
  • In fracture problems, stress intensity factors obtained theoretically and experimentally have been effectively utilized in the analytical evaluation of the cracks effect. The effect of surface crack of a cylindrical and a hollow cylindrical bar is investigated, as well as the effect of the thickness of a hollow cylindrical bar and inclined crack of a hollow cylinder subjected to torsion moment. In this study, stress intensity factor Km of mode III which expresses the stress state in the neighborhood of a crack tip is used. Stress analysis was conducted of the inside of a hollow cylinder in the axial direction of three dimensional crack tip subjected to torsion moment by combining the caustics method and the stress freezing method.

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