• 제목/요약/키워드: fatigue endurance

검색결과 210건 처리시간 0.023초

Tabebuia avellanedae 추출물의 운동능력 향상 효과 (Stimulatory Effects of Extracts of Inner Bark from Tabebuia avellanedae on Exercise Endurance Capacity)

  • 김경미;유양희
    • 한국식품영양과학회지
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    • 제43권12호
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    • pp.1937-1941
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    • 2014
  • 능소화과인 Tabebuia avellanedae인 타히보는 중앙아메리카와 남아메리카의 아열대 우림지역에서 서식하며 이들은 민간 약제로 사용되어 왔다. 본 연구는 타히보 추출물의 라디칼 소거활성에 기초한 항산화 활성과 운동능력 향상 효과에 대한 활성을 검토하였다. 타히보로부터 얻은 두 추출물 타히보 열수 추출물(TAW)과 타히보 80% 에탄올 추출물(TAE)의 운동능력 향상 효과와 총 폴리페놀과 플라보노이드 함량과 항산화 활성을 평가하였다. 운동능력 향상 효과는 TAW가 대조군 대비 2.0배, TAE는 1.8배 증가하였다. 두 추출물의 항산화 활성은 라디칼 소거활성(DPPH와 ABTS)으로 평가하였다. 동일 농도에서 TAE는 TAW와 비교하여 라디칼 소거활성이 높게 났고 TAE의 총 폴리페놀 함량이 항산화 활성과 연관되어 있는 것으로 나타났으며, 이는 운동으로 인한 산화스트레스를 방어함으로써 마우스의 운동능력 향상 효과를 나타낸 것으로 사료된다.

Mo-Ti 합금 접착층을 통한 유연 기판 위 구리 배선의 기계적 신뢰성 향상 연구 (Bending Fatigue Reliability Improvements of Cu Interconnects on Flexible Substrates through Mo-Ti Alloy Adhesion Layer)

  • 이영주;신해아슬;남대현;연한울;남보애;우규희;주영창
    • 마이크로전자및패키징학회지
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    • 제22권1호
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    • pp.21-25
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    • 2015
  • 유연 기판에 증착된 구리 박막과 구리 배선의 기계적 피로 현상에 대해 조사하고, 몰리브덴-티타늄 합금 접착 층을 이용해 피로 신뢰성을 향상시키는 연구를 진행하였다. 구리 배선의 경우 구리 박막에 비해 인장 굽힘 피로수명이 약 3배, 압축 굽힘 피로수명은 약 6배 가량 감소하는 것으로 측정되었으며, 기계적 균열 생성에 의한 파괴가 더욱 치명적으로 작용할 수 있다. 몰리브덴-티타늄 접착층이 있을 경우, 구리 배선의 피로수명이 인장과 압축 굽힘 조건 모두 향상되는 결과를 나타냈으며, 이는 접착층에 의한 계면 접착력 상승 효과와 더불어 구리층의 미끄럼 현상을 억제했기 때문으로 추측된다.

Reliable experimental data as a key factor for design of mechanical structures

  • Brnic, Josip;Krscanski, Sanjin;Brcic, Marino;Geng, Lin;Niu, Jitai;Ding, Biao
    • Structural Engineering and Mechanics
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    • 제72권2호
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    • pp.245-256
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    • 2019
  • The experimentally determined mechanical behavior of the material under the prescribed service conditions is the basis of advanced engineering optimum design. To allow experimental data on the behavior of the material considered, uniaxial stress tests were made. The aforementioned tests have enabled the determination of mechanical properties of material at different temperatures, then, the material's resistance to creep at various temperatures and stress levels, and finally, insight into the uniaxial high cyclic fatigue of the material under different applied stresses for prescribed stress ratio. Based on fatigue tests, using modified staircase method, fatigue limit was determined. All these data contributes the reliability of the use of material in mechanical structures. Data representing mechanical properties are shown in the form of engineering stress-strain diagrams; creep behavior is displayed in the form of creep curves while fatigue of the material is presented in the form of S-N (maximum applied stress versus number of the cycles to failure) curve. Material under consideration was 18CrNi8 (1.5920) steel. Ultimate tensile strength and yield strength at room temperature and at temperature of $600^{\circ}C$: [${\sigma}_{m,20/600}=(613/156)MPa$; ${\sigma}_{0.2,20/600}=(458/141)MPa$], as well as endurance (fatigue) limit at room temperature and stress ratio of R = -1 : (${\sigma}_{f,20,R=-1}=285.1MPa$).

궤도차량 탑재장비의 진동 내구성 평가를 위한 시험수준 결정방법 연구 (Determining Vibration Qualification Level for the Equipment Loaded Inside a Tracked Vehicle)

  • 최창하
    • 환경영향평가
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    • 제4권2호
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    • pp.123-130
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    • 1995
  • The equipment composed of many complicated electronic stuffs undergoes diverse stresses caused by mechanical vibrations during its service. Thus, to ensure its proper operation in the field a simulated vibration test has to be carried out in the laboratory with the Vibration Qualification Level, the test specification, which can include the real environment. In this paper we intent to deal with method and procedure for determining the Vibration Qualification Level so as to estimate the vibration-endurance for the equipment precisely.

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알루미늄 단조 Lower Arm 개발 (Development of Forged Aluminum Lower Arm)

  • 조용기;윤병은
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1995년도 제2회 단조심포지엄 단조기술의 진보
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    • pp.74-80
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    • 1995
  • Forged aluminum lower arm has been developed to provide weight reduction of suspension parts. It was utilized FEM analysis in design of parts. Prototype parts were producted to two shape & different forging condition. Difference of forging condition was manufacturing process of stock, forging press, forging die, heat treatment condition. As a result, weight reduction of 44%, 38% was achived. Strength and fatigue endurance of forged aluminum lower arm was excellent.

고장력볼트 냉간압조용 비조질강 특성에 관한 연구 (Mechanical properties and workability of micro-alloyed steel on cold forming of high tension bolt)

  • 이영선;최정묵;황범규;정택우;문영훈
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2009년도 추계학술대회 논문집
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    • pp.132-136
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    • 2009
  • The importance and interests for saving of energy and cost in industry has been steadily grown up. Therefore, process optimization to reduce the processing step and energy is one of the most important things. The micro-alloyed steel of which post-heat-treatment is not necessary, has attractive points for high strength materials. However, for the application of non-heat-treated steel to structural parts, it is necessary to confirm the reliability of mechanical properties. In order to estimate mechanical properties. The microstructure, hardness, tensile strength, compressive strength and tensile fatigue strength of micro-alloyed steel having 900MPa tensile strength has been investigated.

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EMG 분석을 이용한 대퇴직근의 근력추정 (An ENG analysis for estimating the individual capabilities of the rectus femoris muscle)

  • 이면우;이구형
    • 대한산업공학회지
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    • 제7권2호
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    • pp.3-17
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    • 1981
  • Isometric muscle strength has become important as it is realized that a large variation in the human exists and is affected by many personal and environmental factors. Experiments have been performed for estimating the individual capabilities of the quadriceps femoris muscle in man. The surface EMG has been recorded on the belly of the rectus femoris muscle during voluntary isometric continuous exertion at 25%, 50%, 75%, and 100% MVC. As a muscle force (% MVC) increases, the rectified mean EMG amplitude increases in a non-linear form. The rectified mean EMG amplitude also increases in a non-linear with respect to fatigue progression. As the muscle force (% MVC) increases, an endurance time of isometric exertion decreases linearly. Analysis shows that rectified mean EMG amplitude is a consistent and sensitive measure of motor unit recruitments and can be useful in estimating an individual capability of a local muscle. Further, the result satisfies the sufficient condition that type S motor units are recruited first, while large motor units are recruited progressively as the fatigue develops.

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실린더타입 도어클로저의 구조 및 내구해석 (Analysis of Structure and Endurance for Cylinder-type Door Closer)

  • 김민건;정구현;박찬원
    • 한국공작기계학회논문집
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    • 제13권3호
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    • pp.91-97
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    • 2004
  • The door closer is a typical system which consists of spring and damper. The door closer is a device to close the door more slowly. The virtual prototypes of cylinder-type door closer are developed. The simulations of virtual prototype are performed to obtain the load history of the guide pin. The structural strength assessment of the guide pin is performed to verify a design safety. The fatigue life and damage of the guide pin are predicted using a FEMFAT 4.3h based on the finite element analysis.

유한요소법을 이용한 CT 시편의 홀확장 잔류응력 및 응력확대계수 해석 (Analysis of the Residual Stress due to Cold Expansion and Stress Intensity Factor in CT specimen Using Finite Element Method)

  • 장재순;양원호;김철;고명훈;조명래
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.603-608
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    • 2001
  • Recently, cold expansion of fastener holes is commonly used in the aerospace industry to increase the fatigue endurance of airframes. Cold expansion process is used as the retardation of crack initiation in the hole. This treatment leads to an improvement of fatigue behavior due to the compressive residual stresses developed on the hole surface. The residual stress profile depends on the cold expansion ratio. In the present paper, it is shown that residual stress is redistributed due to the application of cold expansion process for CT specimen. It is further shown that residual stress increases in proportion to cold expansion ratio. It is thought that crack growth rate increases as cold expansion ratio.

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자동차 배터리 지지 구조의 진동 피로 해석에 대한 연구 (Study on Vibration Fatigue Analysis of Automotive Battery Supporter)

  • 안상호
    • 자동차안전학회지
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    • 제11권4호
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    • pp.22-27
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    • 2019
  • In this paper, the vibration load and analysis results for automotive battery supporter were performed to provide efficient vibration tolerance performance prediction methods for single-product vibration tolerance testing, and the major influencing factors and considerations for setting up single-unit vibration tolerance tests were reviewed. A common applicable standard load was applied to efficiently predict the performance of single-unit vibrations through the frequency response analysis technique. The results similar to test results can be predicted by checking vulnerable parts of the vehicle components for vibration loads and applying scale factor to standard loads. In addition, it was confirmed that the test conditions with a frequency generating the same durability severity as the endurance test are needed for accurate prediction of the durability of the single-unit vibration tolerance test conditions, and the acceleration and frequency with the conditions that there is no significant nonlinear phenomena in the vibration system are established during the single-unit vibration tolerance test conditions.