• 제목/요약/키워드: Overload effect

검색결과 238건 처리시간 0.026초

직무요구 및 직무자원과 안전순응의 관계에서 직무소진의 매개역할 (The relationship between job demands-resources and safety compliance, and the mediating effect of job burnout)

  • 임명서;안관영
    • 대한안전경영과학회지
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    • 제16권1호
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    • pp.89-99
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    • 2014
  • This paper reviewed the relationship between job demands/resources and safety compliance, and the mediating effect of job burnout. Based on the responses from 247 employees, the results of multiple regression analysis appeared as follow; 1) two demands factors(role ambiguity and role overload) effect positively on safety compliance. 2) job resources factors(autonomy and social support) effect negatively on safety compliance. 3) job burnout effects negatively on safety compliance. 4) job burnout mediates between 4 job demands/resources(role ambiguity and role overload, autonomy, social support) and safety compliance.

고정밀 전류센서를 이용한 RCD 보조트립 장치 개발 (Development of RCD Auxiliary Trip Device by using High Precision Current Sensor)

  • 곽동걸
    • 전기학회논문지
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    • 제58권8호
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    • pp.1532-1537
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    • 2009
  • Nowadays the diversity and large-capacity of electric appliances are strong effect on electrical fires augment in an alarming way. But, as the inactive response characteristics of the existing RCD (Residual Current protective Device) used on low voltage power distribution lines, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore this paper is confirmed the unreliability of the existing RCD by electrical faults simulation and is proposed a auxiliary trip device of RCD by using a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution lines caused by overload or electric short circuit faults. The sensitive reed switch in the proposed ATD (auxiliary trip device) exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and then rapidly cuts off the existing RCD. The proposed auxiliary trip device of RCD is confirmed the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed ATD can also prevent electrical disaster, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.

과부화 방지를 위한 쐐기형 레일클램프의 지지대 위치 설정 (Determining the Position of Supporter to prevent a Overload applied to the Wedge Type Rail Clamp)

  • 한동섭;한근조;이성욱
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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    • pp.294-297
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    • 2006
  • The rail clamp is the device to prevent the crane slips along a rail from the wind blast as well as to locate a container crane in the set position during an operating mode. In this study we conduct the research for determining the proper position of supporter to prevent the overload applied to the rail clamp with respect to the wedge angle in the wedge type rail clamp. The friction force between the jaw pad and the rail to prevent that the crane slips along a rail, when the wind blows, is generated fly the rail-directional wind load. Accordingly the proper position of the supporter to prevent the overload is determined fly analyzing the forces applied to the rail clamp in the wedge working stage. In order to analyze the effect of the wedge angle on the position of supporter, 5-kinds of wedge angles, such as 2, 4, 6, 8, $10^{\circ}$, were adapted as the design parameter, and the wind speed of 40m/s was adapted as the design wind speed criteria.

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단일과대하중에 의한 피로균열추전의 지대지연현상에 관한 연구 (A Study on the Delayed-Retardation of Fatigue Crack Growth Following Single Peak Overload)

  • 오세욱;강상훈
    • 대한기계학회논문집
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    • 제14권5호
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    • pp.1186-1192
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    • 1990
  • 본 연구에서는 이와 같은 과대인장하중의 제하과정중에 발생하는 과대압축소 성역이 과대하중에 의한 피로균열의 진전지연에 미치는 영향을 중심으로 하여, 각 소 성역 치수를 매개변수로 하는 해석적 방법을 통하여 가속지연모델을 제안하고, 이를 2024-T3 Al 합금을 이용한 단일과대하중에 의한 지연시험결과 및 Wheeler 나 Willenb- org 등의 기존의 지연모델과 비교 고찰하고자 한다.

이동식크레인의 과부하방지장치용 광각도 핀형 로드셀의 창의적 설계 (Creative Design of Large-Angle Pin Type Load Cell for the Overload Limiter of a Movable Crane)

  • 한동섭;하정민;한근조
    • 한국기계가공학회지
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    • 제9권1호
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    • pp.35-41
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    • 2010
  • An overload limiter is used to prevent its overturning accident during an operation of a movable crane. Recently the indirect measuring method, which measures hoisting load and overturning moment of overload limiter, demands instead of the existing method, which measures only hoisting load. The indirectly measuring method is how to conduct the hoisting load and overturning moment as measuring the load of hydraulic cylinder for a luffing driving of boom. So we need to develop the multi-angular pin type load cell with the measuring angle of ${\pm}10$ degree instead of the existing load cell with the measuring angle of ${\pm}2$ degree. In this study the finite element analysis is conducted to evaluate the effect of the aspect ratio of measuring cross section on the measuring limit of the load cell to develop the many-angular pin type load cell. For this investigation, the aspect ratio of measuring cross section and load applying angle were adopted as design parameters and the stresses of measuring part were evaluated for each parameter.

혼합모드 단일과대하중 하에서 피로균열 전파거동의 예측 (Prediction of Fatigue Crack Propagation Behavior Under Mixed-Mode Single Overload)

  • 이정무;송삼홍
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2004년도 추계학술대회
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    • pp.359-364
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    • 2004
  • In this study, experiments were tried on the mixed-mode I+II single overloading model which changes the loading mode of overload and fatigue load. Aspects of deformation field in front of the crack which is formed by mixed-mode I+II single overloading were experimentally studied. Then the shape and size of mixed-mode plastic zone were approximately calculated. The propagation behavior of fatigue crack was examined under the test conditions combined by changing the loading mode. The behavior of fatigue cracks were greatly affected by shapes of plastic deformation field and applying mode of fatigue load. Accuracy of prediction and evaluation for fatigue life may be improved by considering all aspects of deformation and behavior of fatigue cracks.

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7075-T73 알루미늄 합금의 피로균열진전거동 및 지연현상에 미치는 두께의 영향 (Effect of specimen thickness on fatigue crack growth and retardation behavior of 7075-T73 aluminum alloy)

  • 김정규;박병훈;류석현
    • 대한기계학회논문집
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    • 제13권4호
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    • pp.670-679
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    • 1989
  • 본 연구에서는 항공기 구조용 재료로서 널리 사용되는 국산 고장력 7075-T73 알류미늄 합금을 준비하고 일정진폭하중 및 단일과대하중에 의한 피로균열 진전거동에 미치는 두께의 영향과 이의 기구를 검토하였다.

Improvement to Crack Retardation Models Using ″Interactive Zone Concept″

  • Lee, Ouk-Sub;Chen, Zhi-Wei
    • International Journal of Precision Engineering and Manufacturing
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    • 제3권4호
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    • pp.72-77
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    • 2002
  • The load interaction effect can be best illustrated by the phenomenon of overload retardation. Some prediction methods for retardation are reviewed and the problems discussed in the present paper. The so-called under-load effect much of the retardation disappears if a very low level minimum stress follows the overload, is also of importance for a prediction model to work properly under random load spectrum. The concept of Interactive Zone (IZ) fully considering reversed plasticity during unloading was discussed. This IZ concept can be combined with existing models to derive some improved models that can naturally take account of the under-load effect. Some simulations by IZ improved models for test under complex load sequences including multiple overloads and both over/under loads are compared with test results. It is seen that the improvement by IZ concept greatly enhanced the ability of existing models to accommodate complex load interaction effects.

과대하중이 피로수명에 미치는 영향에 관한 연구 (A Study on the Effect of Overloading on Fatigue Life)

  • 김경수;신병천;심천식;박진영;조형민
    • 대한조선학회논문집
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    • 제40권3호
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    • pp.45-53
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    • 2003
  • Ships and ocean structures are subjected to random loads caused by irregular waves. The irregularity of amplitude from random loading affects on fatigue crack growth and fatigue life. However the effects of irregularity of loading on fatigue including random loading have not been explained exactly. Therefore in this paper crack growth tests on DENT specimens under constant-amplitude loading including a single tensile overload are conducted to investigate the effect of overload on crack growth rate. The size of plastic zone and crack growth rate before and after a single tensile overloading are measured using ESPI system. Crack growth retardation model that is characterized by crack growth length and the size of plastic zone was proposed and compared with test result. From the research, the validity of proposed model is examined on crack growth retardation, and consequently fatigue life.