• Title/Summary/Keyword: failure factor

검색결과 2,042건 처리시간 0.03초

Reliability Equivalence Factors of n-components Series System with Non-constant Failure Rates

  • Mustafa, A.
    • International Journal of Reliability and Applications
    • /
    • 제10권1호
    • /
    • pp.43-57
    • /
    • 2009
  • In this article, we study the reliability equivalence factor of a series system. The failure rates of the system components are functions of time t. we study two cases of non-constat failure rates (i) weibull distribution (ii) linear increasing failure rate distribution. There are two methods are used to improve the given system. Two types of reliability equivalence factors are discussed. Numerical examples are presented to interpret how one can utilize the obtained results.

  • PDF

암반 사면의 파괴 예측을 위한 불연속면 분포 특성 분석 (Analysis of Discontinuity Distribution Property to Predict Rock Slope Failure)

  • 윤운상;김정환;배기훈
    • 한국지반공학회:학술대회논문집
    • /
    • 한국지반공학회 1999년도 가을 학술발표회 논문집
    • /
    • pp.147-152
    • /
    • 1999
  • Distribution of fracture system is an important factor to analyse instability of jointed rock slope. In the most case of rock slopes, joint distribution properties are related to potential, shape, size and locality of slope failure. The purpose of this paper is to present an application of fracture characterization related to rock slope failure. Fracture data used in this study are collected by scanline survey. Two aspects of fracture characterization for rock slope are handled in this study First, In order to determine the potential and shape of slope failure, trace length of joints is considered as the weighting factor about collected orientation data. Second, Relationship between trace length and spacing is analysed to estimate failure location and size. The distribution of fracture system is directly influenced on wedge failure. It is effective to analyse the orientation of fractures by using weighting factors associated with the trace length of fractures rather than to analyse only that of fractures. It gives a conclusion that the wedge failure occurred along the peak of fracture density(or intensity) cycles.

  • PDF

Numerical analysis of a complex slope instability: Pseudo-wedge failure

  • Babanouri, Nima;Sarfarazi, Vahab
    • Geomechanics and Engineering
    • /
    • 제15권1호
    • /
    • pp.669-676
    • /
    • 2018
  • The "pseudo-wedge" failure is a name for a complex instability occurring at the Sarcheshmeh open-pit mine (Iran). The pseudo-wedge failure contains both the rock bridge failure and sliding along pre-existing discontinuities. In this paper, a cross section of the failure area was first modeled using a bonded-particle method. The results indicated development of tensile cracks at the slope toe which explains the freedom of pseudo-wedge blocks to slide. Then, a three-dimensional discrete element method was used to perform a block analysis of the instability. The technique of shear strength reduction was used to calculate the factor of safety. Finally, the influence of geometrical characteristics of the mine wall on the pseudo-wedge failure was investigated. The safety factor significantly increases as the dip and dip direction of the wall decrease, and reaches an acceptable value with a 10-degree decrease of them.

SCP개량지반상에 성토시공 시 최적설계에 관한 연구 (Study on Optimum Design for Embankment Construction on Soft Ground Treated by SCP)

  • 채종길;박영목;정민수
    • 대한토목학회논문집
    • /
    • 제29권6C호
    • /
    • pp.251-258
    • /
    • 2009
  • 본 연구에서는 모래다짐말뚝 (SCP)로 개량된 연약점토지반상의 성토시공에 있어서 최적설계조건에 대해 현행 설계법과 손실평가함수 및 1차 근사 2계 모멘트법 (AFOSM)에 기초한 신뢰성 설계법으로 비교 검토하였다. 결과를 요약하면 다음과 같다. 1) 안전율(Fs)와 파괴확률($P_F$)는 심한 비선형 관계를 나타냈고, Fs가 1.2로 증가함에 따라 $P_F$는 약 1%까지 급격한 감소를 나타낸 후, 안전율의 증가와 더불어 $P_F$는 점진적으로 감소하였다. 현행 설계법상의 기준 안전율 1.2는 둘의 관계에 있어서 일종의 임계값이며, 이들의 관계가 적절히 고려되어 정립되었다고 판단된다. 2) 최소기대총비용을 나타내는 안전율은 1.15부근으로 현행설계기준 1.2에 다소 못미치는 값으로 나타났고, 파괴확률은 1% 정도로 다소 컸다. 3) 응력분담비 n과 모래의 내부마찰각 ${\phi}$의 민감도가 연약층의 초기비배수강도 관련 변수들의 민감도보다 더 크게 나타났다. 이것은 n과 ${\phi}$의 변동 특성이 보다 해석결과에 큰 영향을 준다는 것과 이들 변동 특성은 SCP 개량지반상의 성토안정해석에 반드시 고려되어야 함을 의미한다. 4) 설계기준안전율 1.2 이상(파괴확률 0.1-0.3% 이하)에서 New Failure Point는 평균치에서 표준편차의 1~2배 가량 떨어져 있는 값을 나타냈다.

MZ세대의 창업실패두려움 : 재정적, 심리적, 행동적 요인의 영향 (The MZ Generation's Fear of Startup Failure : Effects of Financial, Psychological, and Behavioral Factors)

  • 김현배;이수진
    • 벤처혁신연구
    • /
    • 제7권3호
    • /
    • pp.141-157
    • /
    • 2024
  • 창업이나 창업의도에 관한 연구들이 활발하게 진행되고 있다. 본 연구는 창업의도에 영향을 미치는 다양한 요인 중에서 창업실패두려움에 초점을 두고 진행했다. 특히 MZ세대를 대상으로 창업실패두려움에 영향을 미칠 요인으로 재정적, 심리적, 행동적 요인을 설정하였다. MZ세대 200명을 대상으로 자료를 수집하여 구조방정식으로 실증 분석하였으며 결과는 다음과 같다. 재정적요인(가용자금부족), 심리적요인(위험회피, 스트레스회피)은 실패두려움에 유의한 정(+)의 영향을 미치는 것으로 나타났다. 반면 행동적요인(힘든일회피)과 실패두려움간의 유의성은 검정되지 않았다. MZ세대의 창업실패두려움에 영향을 미치는 영향력의 크기는 스트레스회피, 위험회피, 가용자금부족 순으로 나타났다. 창업실패두려움은 MZ세대의 창업의도에 유의한 부(-)의 영향을 미치는 것으로 나타났다. 또한 창업실패두려움은 심리적요인(위험회피, 스트레스회피) 및 행동적요인(힘든일회피)과 창업의도간 매개역할을 하는 것으로 나타났다. 하지만 재정적요인인 가용자금부족과 창업의도간 매개효과는 검정되지 않았다. 이러한 연구결과는 창업의도 관련 연구에서 보다 세밀하게 분석을 했다는 점에서 학술적인 의의가 있다. 또한 MZ세대의 창업의도를 증진시키기 위해 실패에 대한 두려움을 제거할 수 있는 요인에 대한 실무적인 시사점을 제시했다는 점에서 본 연구의 의의가 있다.

글로벌 대형유통기업의 서비스 실패에 관한 사례 연구: 서비스 마케팅믹스별 실패요인을 중심으로 (The Service Failure of Global Large Distribution Companies: the Failure Factors by Service Marketing Mix)

  • 이용재;최석봉
    • 품질경영학회지
    • /
    • 제47권3호
    • /
    • pp.641-659
    • /
    • 2019
  • Purpose: Recently, the managing customer complaints properly has emerged as key source of competitive advantage in the large distribution industry. Effective customer complaint management helps firms minimize service failures and incense the capability to respond to customer's needs. Despite this importance, the in-depth prior study of a firm's service failures is very limited. Therefore, the actual service failure cases of large discount stores in Korea were analyzed in this study, and the types of service failures that occur at the service interface were identified. Method: Specifically, a total of 48,307 cases of customer complaints that have occurred in the past three years were collected from 1 January 2016 to 31 December 2018. Using 7 dimensions of service marketing mix. we have classified and analyzed systematically the service failure cases collected. Results: Among the cases of service failures, 34,921 (72.3%) cases were involved with the product factor, followed by 6,152 (12.7%) cases with person factor and 5,392 (11.2%) cases with process factor. Conclusion: By linking the main causes of service failure with the service marketing mix variables, this research presented a more systematic analytic model and verified by applying it to large domestic distribution company. Understanding the main factors affecting customer complaints n the large distribution industry can provide managers useful information and insight who want to achieve an effective customer complaint management.

Probabilistic analysis of anisotropic rock slope with reinforcement measures

  • Zoran Berisavljevic;Dusan Berisavljevic;Milos Marjanovic;Svetlana Melentijevic
    • Geomechanics and Engineering
    • /
    • 제34권3호
    • /
    • pp.285-301
    • /
    • 2023
  • During the construction of E75 highway through Grdelica gorge in Serbia, a major failure occurred in the zone of reinforced rock slope. Excavation was performed in highly anisotropic Paleozoic schist rock formation. The reinforcement consisted of the two rows of micropile wall with pre-stressed anchors. Forces in anchors were monitored with load cells while benchmarks were installed for superficial displacement measurements. The aim of the study is to investigate possible causes of instability considering different probability distributions of the strength of discontinuities and anchor bond strength by applying different optimization techniques for finding the critical failure surface. Even though the deterministic safety factor value is close to unity, the probability of failure is governed by variability of shear strength of anisotropic planes and optimization method used for locating the critical sliding surface. The Cuckoo search technique produces higher failure probabilities compared to the others. Depending on the assigned statistical distribution of input parameters, various performance functions of the factor of safety are obtained. The probability of failure is insensitive to the variation of bond strength. Different sampling techniques should yield similar results considering that the sufficient number of safety factor evaluations is chosen to achieve converged solution.

하중의 분산성을 고려한 대수누선사면 파괴의 확률론적 해석 (A Probabilistic Analysis on Logarithmic-Spiral Failure of Slope in Consideration of Load Variance)

  • 정성관;권무남
    • 한국지반공학회지:지반
    • /
    • 제4권4호
    • /
    • pp.39-50
    • /
    • 1988
  • 현재까지 사면의 안정해석은 거의 결정론적 방법에 의해서 도호사면을 대상으로 연구가 수행되어 왔다. 그러나 실제적으로 사면의 파괴형상은 대수나선, 복합직선, 정원형, Cycloid기선 등의 다양 한 형태를 나타내고 있다. 따라서 본 연구는 지하수위를 고려한 기류한 사면의 파괴형상을 대수나선으로 하고 하중과 흙의 강침정수의 확률변수분포를 정규분포, 대수정규분포 및 베타분포로 가정하여 사면의 파괴확률을 구했다. 그치고 사면안정설계에 이용되고 있는 안전률과 파괴확률과의 관계를 분석하여 허용안전률에 대한 신잡실를 판단하기 위하여 수행되었다. 그 결과로 동일한 안전률에 대해서 변리계수가 증가함에 따라서 파괴확률이 증가하므로 사면설계에 있어서 안전률보다 파괴덕률을 이용하는 것이 합리적이라고 생각된다. 또한 허용안전률은 현장 조건을 고려하여 결정하는 것보다는 강도정수의 변리계수에 의하여 결정하는 것이 더 타당하다고 판단된다.

  • PDF

경사제 피복재의 안정성 해석을 위한 동력학적 신뢰성 모형 (Dynamic Reliability Model for Stability Analysis of Armor Units on Rubble-Mound Breakwater)

  • 이철응
    • 산업기술연구
    • /
    • 제21권B호
    • /
    • pp.163-174
    • /
    • 2001
  • A dynamic reliability model for analyzing the stability of armor units on rubble-mound breakwater is mathematically developed by using Hudson's formula and definition of single-failure mode. The probability density functions of resistance and loading functions are defined properly, the related parameters to those probability density functions are also estimated straightforwardly by the first-order analysis. It is found that probabilities of failure for the stability of armor units on rubble-mound breakwater are continuously increased as the service periods are elapsed, because of the occurrence of repeated loading of random magnitude by which the resistance may be deteriorated. In particular, the factor of safety is incorporated into the dynamic reliability model in order to evaluate the probability of failure as a function of factor of safety. It may thus be possible to take some informations for optimal design as well as managements and repairs of armor units on rubble-mound breakwater from the dynamic reliability analyses.

  • PDF

디지털 원자로 보호시스템의 공통원인고장 분석에 관한 사례연구 (A Case Study of the Commom Cause Failure Analysis of Digital Reactor Protection System)

  • 공명복;이상용
    • 산업공학
    • /
    • 제25권4호
    • /
    • pp.382-392
    • /
    • 2012
  • Reactor protection system to keep nuclear safety and operational economy of plants requires high reliability. Such a high reliability of the system can be achieved through the redundant design of components. However, common cause failures of components reduce the benefits of redundant design. Thus, the common cause failure analysis, to accurately calculate the reliability of the reactor protection system, is carried out using alpha-factor model. Analysis results to 24 operating months are that 1) the system reliability satisfies the reliability goal of EPRI-URD and 2) the common cause failure contributes 90% of the system unreliability. The uncertainty analysis using alpha factor parameters of 0.05 and 0.95 quantile values shows significantly large difference in the system unreliability.