• 제목/요약/키워드: local stress

검색결과 1,244건 처리시간 0.021초

Factors Related to Regional Variation in the High-risk Drinking Rate in Korea: Using Quantile Regression

  • Kim, Eun-Su;Nam, Hae-Sung
    • Journal of Preventive Medicine and Public Health
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    • 제54권2호
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    • pp.145-152
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    • 2021
  • Objectives: This study aimed to identify regional differences in the high-risk drinking rate among yearly alcohol users in Korea and to identify relevant regional factors for each quintile using quantile regression. Methods: Data from 227 counties surveyed by the 2017 Korean Community Health Survey (KCHS) were analyzed. The analysis dataset included secondary data extracted from the Korean Statistical Information Service and data from the KCHS. To identify regional factors related to the high-risk drinking rate among yearly alcohol users, quantile regression was conducted by dividing the data into 10%, 30%, 50%, 70%, and 90% quantiles, and multiple linear regression was also performed. Results: The current smoking rate, perceived stress rate, crude divorce rate, and financial independence rate, as well as one's social network, were related to the high-risk drinking rate among yearly alcohol users. The quantile regression revealed that the perceived stress rate was related to all quantiles except for the 90% quantile, and the financial independence rate was related to the 50% to 90% quantiles. The crude divorce rate was related to the high-risk drinking rate among yearly alcohol users in all quantiles. Conclusions: The findings of this study suggest that local health programs for high-risk drinking are needed in areas with high local stress and high crude divorce rates.

The role of peroxidases in the pathogenesis of atherosclerosis

  • Park, Jong-Gil;Oh, Goo-Taeg
    • BMB Reports
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    • 제44권8호
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    • pp.497-505
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    • 2011
  • Reactive oxygen species (ROS), which include superoxide anions and peroxides, induce oxidative stress, contributing to the initiation and progression of cardiovascular diseases involving atherosclerosis. The endogenous and exogenous factors hypercholesterolemia, hyperglycemia, hypertension, and shear stress induce various enzyme systems such as nicotinamide adenine dinucleotide (phosphate) oxidase, xanthine oxidase, and lipoxygenase in vascular and immune cells, which generate ROS. Besides inducing oxidative stress, ROS mediate signaling pathways involved in monocyte adhesion and infiltration, platelet activation, and smooth muscle cell migration. A number of antioxidant enzymes (e.g., superoxide dismutases, catalase, glutathione peroxidases, and peroxiredoxins) regulate ROS in vascular and immune cells. Atherosclerosis results from a local imbalance between ROS production and these antioxidant enzymes. In this review, we will discuss 1) oxidative stress and atherosclerosis, 2) ROS-dependent atherogenic signaling in endothelial cells, macrophages, and vascular smooth muscle cells, 3) roles of peroxidases in atherosclerosis, and 4) antioxidant drugs and therapeutic perspectives.

용접 토우부의 국부적 변형률 측정을 통한 용접부의 정적 과하중에 따른 피로강도의 변화 평가 (The Static Overload Effect Estimations on Fatigue Strength by The Measurement of Local Strain Variation at The Weldment Toe)

  • 이현우;김주환;김현재
    • 한국정밀공학회지
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    • 제18권6호
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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.

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Uniaxial Compression Behavior of High-Strength Concrete Confined by Low-Volumetric Ratio Lateral Ties

  • Hong Ki-Nam;Han Sang-Hoon
    • 콘크리트학회논문집
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    • 제17권5호
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    • pp.843-852
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    • 2005
  • Presently, test results and stress-strain models for poorly confined high-strength columns, more specifically for columns with a tie volumetric ratio smaller than $2.0\%$, are scarce. This paper presents test results loaded in axial direction for square reinforced concrete columns confined by various volumetric ratio lateral ties including low-volumetric ratio. Test variables include concrete compressive strength, tie yield strength, tie arrangement type, and tie volumetric ratio. Local strains measured using strain gages bonded to an acryl rod. For square RC columns confined by lateral ties, the confinement effect was efficiently improved by changing tie arrangement type from Type-A to Type-B. A method to compute the stress in lateral ties at the concrete peak strength and a new stress-strain model for the confined concrete are proposed. Over a wide range of confinement parameters, the model shows good agreement with stress-strain relationships established experimentally.

Offset 구조 Poly-Si TFT의 Negative Bias Stress 효과 (Negative Bias Stress Effect with Offset Structure in Poly-Si TFT's)

  • 이제혁;변문기;임동규;조봉희;김영호
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1998년도 추계학술대회 논문집
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    • pp.141-144
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    • 1998
  • The electrical characteristics of poly-Si TFT's with offset structure by negative bias stress are systematically investigated as a function of offset length. The changes of electrical characteristics, V$\_$th/, off-current, on/off ratio, in the offset structured poly-Si TFT's are smaller than that of the conventional structured poly-Si TFT's under the stress condition (V$\_$ds/=20V, V$\_$gs/=-20V). It is found that the hot carrier effect by negative bias stress is suppressed by the offset structured poly-Si TFT's because the local electric field near the drain region is decreased by offset region.

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Stress Analysis in Polymeric Coating Layer Deposited on Rigid Substrate

  • Lee, Sang Soon
    • Corrosion Science and Technology
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    • 제14권4호
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    • pp.161-165
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    • 2015
  • This paper presents an analysis of thermal stress induced along the interface between a polymeric coating layer and a steel substrate as a result of uniform temperature change. The epoxy layer is assumed to be a linear viscoelastic material and to be theromorheologically simple. The viscoelastic boundary element method is employed to investigate the behavior of interface stresses. The numerical results exhibit relaxation of interface stresses and large stress gradients, which are observed in the vicinity of the free surface. Since the exceedingly large stresses cannot be borne by the polymeric coating layer, local cracking or delamination can occur at the interface corner.

풍력발전기용 대형 복합재 블레이드에 대한 구조 해석 및 사이징에 관한 연구 (Stress Analysis and Sizing for a Glass/Epoxy Composite Wind Turbine Blade)

  • 이충훈;박진무;홍순곤;박지상;김태욱
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2002년도 추계학술발표대회 논문집
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    • pp.5-9
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    • 2002
  • This paper presents a method and procedure for stress analysis and sizing in development of structures of a large composite wind turbine blade. Structural requirement of IEC standard was reviewed to set up appropriate analysis method and procedure. Several structural layouts were examined in a viewpoint of a large scale wind turbine blade. For the critical load cases, stress analysis were performed using finite element method. Stacking sequence and thickness of a laminate for each part and location were determined considering stress levels and producibility. Nonlinear geometric analysis was performed to check stability problem due to local buckling of a skin structures.

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충격하중에 의한 용접구조물의 강도 증가에 관한 연구 (A Study on the strength improvement in weldment by the impact loading)

  • 양영수
    • 한국생산제조학회지
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    • 제9권3호
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    • pp.76-82
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    • 2000
  • It is well known that during the oxygen cutting process residual thermal stresses are produced in weldment. The local non-uniform heating and subsequent cooling which takes place during any welding process causes complex thermal strains and stresses to finally lead to residual stresses exceed to the yield stress. High tensile stresses combined with applied structural load in the region near the welded joint can given rise to distortion brittle fracture change of the fatigue strength and stress corrosion cracking. The appropriate treatment of the welded component which reduces the peak of he welding residual stresses is believed to lower risk of the fracture during the service of the structure. In this study the impact loading in oxygen cutting frame was applied to reduce the residual stress. After applying the impact loading redistribution of resid-ual stress was measured by cutting method and the effect of fatigue was tested.

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Local stress field for torsion of a penny-shaped crack in a transversely isotropic functionally graded strip

  • Feng, W.J.;Su, R.K.L.
    • Structural Engineering and Mechanics
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    • 제18권6호
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    • pp.759-768
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    • 2004
  • The torsion of a penny-shaped crack in a transversely isotropic strip is investigated in this paper. The shear moduli are functionally graded in such a way that the mathematics is tractable. Hankel transform is used to reduce the problem to solving a Fredholm integral equation. The crack tip stress field is obtained by taking the asymptotic behavior of Bessel function into account. The effects of material property parameters and geometry criterion on the stress intensity factor are investigated. Numerical results show that increasing the shear moduli's gradient and/or increasing the shear modulus in a direction perpendicular to the crack surface can suppress crack initiation and growth, and that the stress intensity factor varies little with the increasing of the strip's height.

치과기공사들의 직무스트레스와 정신건강에 관한 연구 - 서울지역을 중심으로 - (A study on relationships between Job stress and Mental health for dental technicians)

  • 최승희;이청재
    • 대한치과기공학회지
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    • 제29권2호
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    • pp.163-171
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    • 2007
  • The purpose of this study is comprehension for relationships between job stress and mental health for dental technicians in performing their duties. and this study can make use of opportunity of accumulation of data on dental technician's health care and work environment in future. Job stress for dental technicians served in general hospital dental laboratory were more highly effected than in local dental laboratory. and this result was statistically reliable. There were no meaningful differences in mental health between dental technician in dental laboratory in dental climic dental laboratory and commercial dental laboratory. and this result was not statistically reliable. The analysis of this study could be used by preliminary data to further research of relationships between job stress and mental health for dental technicians in the future. This study was made progress partially under limited members of dental technician in Seoul. so future studies are suggested that the more advanced total figure study for whole dental technicians in Korea.

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