• Title/Summary/Keyword: Common stress

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Stress concentration factors for multi-planar tubular KK-joints of jacket substructures in offshore wind turbines

  • Hamid Ahmadi;Adel Alizadeh Atalo
    • Ocean Systems Engineering
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    • v.14 no.3
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    • pp.237-259
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    • 2024
  • Although the investigation on the effect of loaded out-of-plane braces on the values of the stress concentration factor (SCF) in offshore tubular joints has been the objective of numerous research works, a number of quite important cases still exist that have not been studied thoroughly due to the diversity of joint types and loading conditions. One of these cases is the multi-planar tubular KK-joint subjected to axial loading. Tubular KK-joints are among the most common joint types in jacket substructure of offshore wind turbines (OWTs). In the present research, data extracted from the stress analysis of 243 finite element (FE) models, verified against available experimental data, was used to study the effects of geometrical parameters on the chord-side SCFs in multi-planar tubular KK-joints subjected to axial loading. Parametric FE study was followed by a set of nonlinear regression analyses to develop three new SCF parametric equations for the fatigue analysis and design of axially loaded multi-planar KK-joints.

A Study on Resisting Force of H-Shaped Beam Using Glass Web Plate (유리 웨브를 사용한 H형 합성보의 내력에 관한 연구)

  • Son, Ki-Sang;Jeon, Chang-Hyun
    • Journal of the Korean Society of Safety
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    • v.21 no.3 s.75
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    • pp.73-80
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    • 2006
  • Generally beam design depends on the yielding and maximum strength of each member varying with its section shape. Web plate of H-shape beam has not been substituted with glass plate, because it is known that its strength and heat properties are different and it is limited to substitute the existing steel web with glass element. Ceiling height of each room should be decreased with more than 60-80cm due to the beam. Differently from this condition, glass web beam has a good point to see through it and sunshine can be penetrate into the other size especially when it is installed as of outside wall. And also, it can be safer due to controlling room inside easier, if the strength is applicate. This study is to show some applicability after finding out the properties using the test. The test members with a size of $1,600{\times}200{\times}300{\times}9mm$ being SS41 rolled steel having THK 9mm flange while having 8,10mm and reinforced glass 12mm thickness is bonded with epoxy bond under the condition of temperature $28^{\circ}C$, humidity 50%, bonding power 24Mpa. It is show reinforced glass has 5 times of fracture stress more than the common glass but $50{\sim}150%$ difference between these 2 kinds of glass was shown. Reinforce glass did not support the original upper flange after fracture but the common glass did the upper flange after unloading. Generally reinforced glass is stronger than the common one but the common glass having a part of crack on it, compared with reinforced glass having the overall fracture could be more useful in case of needing ductility.

Factors that affect the muscular skeletal diseases of some industrial workers working in Changwon-si, Gyeongsangnam-do and the aspects of pain

  • Lee, Jun Cheol;Kim, Kyung
    • Journal of International Academy of Physical Therapy Research
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    • v.7 no.1
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    • pp.938-948
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    • 2016
  • In the present study, the general characteristics, job stress, working conditions, and aspects of pain of some industrial workers working in Changwon-si, Gyeongsangnam-do, were surveyed. In analyzing the relationship between job stress and the existence of pain, the variables "working speed" and "opportunities to develop abilities" were shown to have statistically significant relationships with the existence of pain ($p{\leq}.05$). Regarding the relationship between working conditions and the existence of pain, the variables" amount of work per hour," "amount of work per day," "number of parts handled during work," "work production per person," and" inconvenient postures or motions during work" were shown to have statistically significant relationships with the existence of pain($p{\leq}.05$). Regarding aspects of pain", within 1~3 years" was the most common answer to time of occurrence of symptoms, with a percentage of 27.6%; "appear almost always" was the most common answer to frequency of symptoms, with a percentage of 37.1%; "slight pain" was the most common answer to degree of pain, with a percentage of 50.5%; and "moderate" was the most common answer to encumbrance caused by pain to living and work, with a percentage of 41.2%. The aim of the present study was to determine the factors that affect pain due to musculoskeletal diseases in industrial workers and to define the aspects of pain in order to provide basic data for the preparation of measures to prevent musculoskeletal diseases. To control pain due to musculoskeletal diseases, factors that affect pain, as well as the aspects of pain, should be recognized early, and efforts should be made to supplement and improve systems for preventing recurrence.

Study of biochemical factors and stress in Korean Adults (한국인 성인에서 스트레스에 대한 생화학적 요인 분석 연구)

  • Lee, Bum Ju
    • The Journal of the Convergence on Culture Technology
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    • v.7 no.1
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    • pp.31-36
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    • 2021
  • Stress is a common risk factor for health and is associated with the endocrine gland and immune system. Studies on the association between stress and biochemical factors have been conducted worldwide, but studies on the association have been rare in South Korea. Therefore, the aims of this study are to analyze the relationship of stress with demographic information and biochemical factors for domestic adults and derive risk factors for stress. For data analysis, stress and normal groups were analyzed using binary logistic regression. In both men and women, age and average daily sleep time during the weekday were highly associated with stress, and the depression score (Patient Health Questionnaire-9) was also highly related with stress. In women, white blood cell levels were highly associated with stress, and in men, red blood cell levels were highly related with stress. These findings will contribute to the prevention of stress and the national health in the future.

A Comparative Study of Job Satisfaction and Stress Coping Strategies of Teachers in Early Childhood Education and Care According to Their Personality Types (영유아교사의 성격유형에 따른 직무만족도와 스트레스 대처 방식의 차이)

  • Chae, Jin Young;Kwon, Hye Jin
    • Korean Journal of Childcare and Education
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    • v.8 no.3
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    • pp.5-23
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    • 2012
  • The purpose of this study was to investigate and compare how the Enneargram personality types of teachers in early childhood education and care would affect their job satisfaction and stress coping strategies. The findings are as follows. First, as to the distribution of the participants' Enneargram personality types, the most common was the Peacemaker type and the least common was the Achiever type. Second, for teachers' job satisfaction, there was a statistically significant difference in the job-related subcategory according to their personality types. The post-hot comparison showed that the Loyalist type showed the lowest score in job-related job satisfaction. Third, in terms of stress coping strategies, there was a statistically significant difference in the psychological coping strategy according to their personality types. The post-hot comparison showed that the Individualist type showed the highest score in psychological coping strategy. The implications for future studies are also discussed.

Study on the mental stress of the invalids with the four most common chronic illnesses and their congenital diseases in light of the four pillars of destiny -centering on the elderly in Seoul nursing homes (4대 중증질환자의 정서적 스트레스와 명리학적 선천성 질환에 관한 연구 -서울시 요양원 입소노인을 중심으로-)

  • Kim, Il-Sin;Cho, Sung-Je
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.8
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    • pp.3715-3723
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    • 2013
  • The objective of this study is to analyze the correlations between the chronic illnesses and congenital diseases of the chronic elderly invalids in nursing homes, as well as to examine the impact of stress scale and the factors affecting the emotional burnout scale. This study conducted Seoul survey from March 15 to May 31, 2013, targeting 147 seniors in nursing homes who were suffering from the four most common chronic illnesses. Analyses performed in this study include frequency, correlation and simple regression analyses, t-test and one-way analysis of variance, etc. All of the empirical analyses were conducted at 5% level of significance. The result of the study shows that there is a high correlation between the chronic invalids and their congenital diseases determined by the four pillars of destiny and that, if they are found to have a chronic illness, patients experience a high level of stress. Persons who score higher on the stress scale tend to score higher in the emotional burnout scale.

Oxidative Stress in Extrahepatic Tissues of Rats Co-Exposed to Aflatoxin B1 and Low Protein Diet

  • Rotimi, Oluwakemi A.;Rotimi, Solomon O.;Oluwafemi, Flora;Ademuyiwa, Oladipo;Balogun, Elizabeth A.
    • Toxicological Research
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    • v.34 no.3
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    • pp.211-220
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    • 2018
  • Early life exposure to aflatoxin B1 (AFB1) and low protein diet through complementary foods during weaning is common in parts of Africa and Asia. This study evaluated the effect of co-exposure to AFB1 and low protein diet on the extrahepatic tissues of rats. Twenty-four three-week old weanling male albino rats were used for this study and were randomly assigned into four groups: group 1 served as control and was fed normal protein diet (20% protein), group 2 was fed low protein diet (5% protein), group 3 was fed normal protein diet + 40 ppb AFB1 while group 4 received low protein diet + 40 ppb AFB1, all for eight weeks. Afterward, biomarkers of anemia (packed cell volume (PCV), hemoglobin) and kidney function (urea, uric acid, and creatinine) were determined in the blood while biomarkers of oxidative stress were determined in the tissues spectrophotometrically. Co-exposure to AFB1 and low protein diet significantly (p < 0.05) decreased body weight gain and PCV, increased biomarkers of kidney functions and induced oxidative stress in the tissues studied. There was significant (p < 0.05) reduction in glutathione concentration while TBARS was significantly increased in the tissues. Co-exposure to AFB1 and low protein diet had additive effects on decreasing the weight gain and potentiation effect of kidney dysfunction in the rats. The co-exposure also decreased antioxidant enzymes and increased oxidant status in the tissues. Our results demonstrate that this co-exposure has deleterious health effects on extrahepatic tissues and should be a public health concern especially in developing countries where AFB1 contamination is common.

Effects of Pinelliae Rhizoma Extract on Sociopsychological Stress (반하(半夏) 추출물이 생쥐의 사회.심리적 스트레스에 미치는 영향)

  • Kim, Su-Youn;Lim, Se-Hyun;Cho, Su-In;Choi, Chang-Won;Kim, Kyeong-Ok
    • Journal of Oriental Neuropsychiatry
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    • v.20 no.3
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    • pp.35-47
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    • 2009
  • Objectives : The effects of Pinelliae Rhizoma extract(PRe) were tested for the anti-stress action. Methods : PRe was fed to ICR male mice($20{\pm}2g$) orally with the dose of 100 mg/kg/day for five days. Mice were exposed to sociopsychological stress by restraining and seeing foot shock stressed mice for one hour for five days. Results : PRe administration had the effect of decreasing serum level of lipid peroxidation. The elevated plus-maze test is designed to detect the effect of anxiolytic drugs, and PRe administration group showed a significant increase of latency time. From Microarray, common features between mind-stimulus related genes and body-stimulus related genes were not so abundant When PRe was administered, there were some changes in distributions of mind-stimulus related genes but the distributions were not recovered to normal status. Conclusions : These results suggest that PRe can effectively rid the sociopsychological stress and stress concrened diseases.

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Numerical Analysis of Welding Residual Stress Using Heat Source Models for the Multi-Pass Weldment

  • Bae, Dong-Ho;Kim, Chul-Han;Cho, Seon-Young;Hong, Jung-Kyun;Tsai, Chon-Liang
    • Journal of Mechanical Science and Technology
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    • v.16 no.9
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    • pp.1054-1064
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    • 2002
  • Numerical prediction of welding-induced residual stresses using the finite element method has been a common practice in the development or refinement of welded product designs. Various researchers have studied several thermal models associated with the welding process. Among these thermal models, ramp heat input and double-ellipsoid moving source have been investigated. These heat-source models predict the temperature fields and history with or without accuracy. However, these models can predict the thermal characteristics of the welding process that influence the formation of the inherent plastic strains, which ultimately determines the final state of residual stresses in the weldment. The magnitude and distribution of residual stresses are compared. Although the two models predict similar magnitude of the longitudinal stress, the double-ellipsoid moving source model predicts wider tensile stress zones than the other one. And, both the ramp heating and moving source models predict the stress results in reasonable agreement with the experimental data.

Residual Stress Evaluation Caused by Press Forming and Welding of 600MPa Class Circular Steel Tube Using Hole-Drilling Strain Gage Method (홀드릴링 변형 게이지법을 이용한 600MPa급 원형 강관 제작상의 잔류응력평가)

  • Im, Sung Woo;Lee, E.T.;Shim, Hyun Ju;Kim, Jong Won;Chang, In Hwa
    • Journal of Korean Society of Steel Construction
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    • v.18 no.5
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    • pp.625-631
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    • 2006
  • Residual stresses in structural materials are stresses that exist in the objective without the application of any service or other external loads. Manufacturing processes are the most common causes of residual stress. To examine the effect and the distribution of residual stress due to press forming and welding in the production of a 600MPa-class steel tube, a residual stress evaluation test was performed. The measurement used the Hole-Drilling Strain Gauge Method and evaluated the distribution of residual stress, which measured a total of 59 places near the welding line.