• Title/Summary/Keyword: Failure Prevention

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Interaction Effects of Lay Theories and Failure Type on Adaptive versus Compensatory Consumption Behavior

  • Choi, Nak-Hwan;Wang, Li;Chen, Chang
    • The Journal of Industrial Distribution & Business
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    • v.9 no.7
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    • pp.19-32
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    • 2018
  • Purpose - This paper aims at exploring the effects of failure types such as failure in promotion orientation and failure in prevention orientation on consumers' consumption behavior, and the moderation role of lay theories in the effects. Research design, data, and methodology - This study employed 2 between-subject designs(failure in promotion orientation vs. failure in prevention orientation) and also 2 (failure in promotion orientation vs. failure in prevention orientation) with implicit self as the within-subject. Chinese consumers participated in the empirical study, and to verify the hypotheses ANOVA, T-test and regression analysis were used. Results - Consumers were more likely to choose adaptive consumption behavior rather than compensatory consumption behavior when they were encountered with failure in promotion orientation versus failure in prevention orientation. Lay theories did play the moderation role in the effect of failure types on consumption behavior. The incremental theorists who think that effort is an important way to accomplish their learning goals showed more willingness to conduct compensatory consumption behavior rather than adaptive consumption behavior. Conclusions - Marketers should put more attention on the ways by which their products can help consumers self-improve when consumers encounter with failure. They should also be aware of the importance of consumers' mindsets when designing and developing advertising messages.

Characterization of the brittleness of hard rock at different temperatures using uniaxial compression tests

  • Chen, Guoqing;Li, Tianbin;Wang, Wei;Guo, Fan;Yin, Hongyu
    • Geomechanics and Engineering
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    • v.13 no.1
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    • pp.63-77
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    • 2017
  • The failure mechanism of a deep hard rock tunnel under high geostress and high geothermalactivity is extremely complex. Uniaxial compression tests of granite at different temperatures were conducted. The complete stress-strain curves, mechanical parameters and macroscopic failure types of the rock were analyzed in detail. The brittleness index, which represents the possibility of a severe brittleness hazard, is proposed in this paperby comparing the peak stress and the expansion stress. The results show that the temperature range from 20 to $60^{\circ}C$ is able to aggravate the brittle failure of hard rock based on the brittleness index. The closure of internal micro cracks by thermal stress can improve the strength of hard rock and the storage capacity of elastic strain energy. The failure mode ofthe samples changes from shear failure to tensile failure as the temperature increases. In conclusion, the brittle failure mechanism of hard rock under the action of thermal coupling is revealed, and the analysis result offers significant guidance for deep buried tunnels at high temperatures and under high geostress.

A Study on Optimal Preventive Maintenance Policy When Failure Rate is Exponentially Increasing After Repair (수리 후 고장률이 지수적으로 증가하는 경우에 최적 예방보전 정책)

  • Kim, Tae-Hui;Na, Myung-Hwan
    • Journal of Applied Reliability
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    • v.11 no.2
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    • pp.167-176
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    • 2011
  • This paper introduces models for preventive maintenance policies and considers periodic preventive maintenance policy with minimal repair when the failure of system occurs. It is assumed that minimal repairs do not change the failure rate of the system. The failure rate under prevention maintenance received an effect by a previously prevention maintenance and the slope of failure rate increases the model where it considered. Also the start point of failure rate under prevention maintenance considers the degradation of system and that it increases quotient, it assumed. Per unit time it bought an expectation cost from under this prevention maintenance policy. We obtain the optimal periodic time and the number for the periodic preventive maintenance by using Nakagawa's Algorithm, which minimizes the expected cost per unit time.

주기적 예방보전의 최적정책에 관한 연구

  • Na Myeong Hwan;Son Yeong Suk;Kim Mun Ju
    • Proceedings of the Korean Reliability Society Conference
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    • 2005.06a
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    • pp.115-120
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    • 2005
  • This paper introduces models for preventive maintenance policies and considers periodic preventive maintenance policy with minimal repair when the failure of system occurs. It is assumed that minimal repairs do not change the failure rate of the system. The failure rate under prevention maintenance received an effect by a previously prevention maintenance and the slope of failure rate increases the model where it considered. Also the start point of failure rate under prevention maintenance considers the degradation of system and that it increases quotient, it assumed. Per unit time it bought an expectation cost from under this prevention maintenance policy. We obtain the optimal period time and the number for the periodic preventive maintenance by using Nakagawa's Algorithm, which minimizes the expected cost rate per unit time. Finally, it suppose that the failure time of a system has a Weibull distribution as an example and we obtain an expected cost rate per unit time the optimal period time and the number when cost of replacement and cost of minimal repair change.

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Effects of interface angles on properties of rock-cemented coal gangue-fly ash backfill bi-materials

  • Yin, Da W.;Chen, Shao J.;Sun, Xi Z.;Jiang, Ning
    • Geomechanics and Engineering
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    • v.24 no.1
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    • pp.81-89
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    • 2021
  • Uniaxial compression tests were conducted on sandstone-CGFB composite samples with different interface angles, and their strength, acoustic emission (AE), and failure characteristics were investigated. Three macro-failure patterns were identified: the splitting failure accompanied by local spalling failure in CGFB (Type-I), the mixed failure with small sliding failure along with the interface and Type-I failure (Type-II), and the sliding failure along with the interface (Type-III). With an increase of interface angle β measured horizontally, the macro-failure pattern changed from Type-I to Type-II, and then to Type-III, and the uniaxial compressive strength and elastic modulus generally decreased. Due to the small sliding failure along with the interface in the composite sample with β of 45°, AE events underwent fluctuations in peak values at the later post-peak failure stage. The composite samples with β of 60° occurred Type-III failure before the completion of initial compaction stage, and the post-peak stress-time curve initially exhibited a slow decrease, followed by a steep linear drop with peaks in AE events.

Characterization of Increases in Volumetric Water Content in Soil Slopes to Predict the Risk of Shallow Failure (토사비탈면 표층붕괴 위험 예측을 위한 체적함수비 증가 특성 연구)

  • Suk, Jae-Wook;Kang, Hyo-Sub;Choi, Sun-Gyu;Jeong, Hyang-Seon;Song, Hyo-Sung
    • The Journal of Engineering Geology
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    • v.30 no.4
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    • pp.485-496
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    • 2020
  • The characteristics of volumetric water content changes in soil slopes were studied here in an effort to identify the signs of heavy rain causing shallow slope failure. Volumetric water contents in cases with and without shallow failure were measured in flume and test-bed experiments. Measurement data from 282 experiments of both types revealed that the volumetric water content gradient in shallow failure events ranged from 0.072 to 0.309. In non-failure cases, the range was 0.01~0.32. Therefore, this one specific value cannot predict shallow slope failure. However, as the volumetric water content gradient increased, there was a clear tendency to shallow failure. By using this trend, criteria for four warning levels are suggested.

Experimental study of crack propagation of rock-like specimens containing conjugate fractures

  • Sun, Wenbin;Du, Houqian;Zhou, Fei;Shao, Jianli
    • Geomechanics and Engineering
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    • v.17 no.4
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    • pp.323-331
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    • 2019
  • The presence of defects in nature changes the physical parameters of the rock. In this paper, by studying the rock-like specimens with conjugated fractures, the horizontal angle and length are changed, and the physical parameters and failure modes of the specimens under uniaxial compression test are analyzed and compared with the results of simulation analysis. The experimental results show that the peak strength and failure mode of the rock-like specimens are closely related to the horizontal angle. When the horizontal angle is $45^{\circ}$, the maximum value is reached and the tensile failure mode is obtained. The fracture length affects the germination and propagation path of the cracks. It is of great significance to study the failure modes and mechanical properties of conjugated fracture rock-like specimens to guide the support of fractured rock on site.

Study on failure behaviors of mixed-mode cracks under static and dynamic loads

  • Zhou, Lei;Chen, Jianxing;Zhou, Changlin;Zhu, Zheming;Dong, Yuqing;Wang, Hanbing
    • Geomechanics and Engineering
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    • v.29 no.5
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    • pp.567-582
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    • 2022
  • In the present study, a series of physical experiments and numerical simulations were conducted to investigate the effects of mode I and mixed-mode I/II cracks on the fracture modes and stability of roadway tunnel models. The experiments and simulations incorporated different inclination angle flaws under both static and dynamic loads. The quasi-static and dynamic testing were conducted by using an electro-hydraulic servo control device and drop weight impact system (DWIS), and the failure process was simulated by using rock failure process analysis (RFPA) and AUTODYN software. The stress intensity factor was also calculated to evaluate the stability of the flawed roadway tunnel models by using ABAQUS software. According to comparisons between the test and numerical results, it is observed that for flawed roadways with a single radical crack and inclination angle of 45°, the static and dynamic stability are the lowest relative to other angles of fractured rock masses. For mixed-mode I/II cracks in flawed roadway tunnel models under dynamic loading, a wing crack is produced and the pre-existing cracks increase the stress concentration factor in the right part of the specimen, but this factor will not be larger than the maximum principal stress region in the roadway tunnel models. Additionally, damage to the sidewalls will be involved in the flawed roadway tunnel models under static loads.

Analysis of the mechanical properties and failure modes of rock masses with nonpersistent joint networks

  • Wu, Yongning;Zhao, Yang;Tang, Peng;Wang, Wenhai;Jiang, Lishuai
    • Geomechanics and Engineering
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    • v.30 no.3
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    • pp.281-291
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    • 2022
  • Complex rock masses include various joint planes, bedding planes and other weak structural planes. The existence of these structural planes affects the mechanical properties, deformation rules and failure modes of jointed rock masses. To study the influence of the parameters of a nonpersistent joint network on the mechanical properties and failure modes of jointed rock masses, synthetic rock mass (SRM) technology based on discrete elements is introduced. The results show that as the size of the joints in the rock mass increases, the compressive strength and the discreteness of the rock mass first increase and then decrease. Among them, the joints that are characterized by "small but many" joints and "large and clustered" joints have the most significant impact on the strength of the rock mass. With the increase in joint density in the rock mass, the compressive strength of rock mass decreases monotonically, but the rate of decrease gradually decreases. With the increase in the joint dip angle in rock mass, the strength of the rock mass first decreases and then increases, forming a U-shaped change rule. In the analysis of the failure mode and deformation of a jointed rock mass, the type of plastic zone formed after rock mass failure is closely related to the macroscopic displacement deformation of the rock mass and the parameters of the joints, which generally shows that the location and density of the joints greatly affect the failure mode and displacement degree of the jointed rock mass. The instability mechanism of jointed surrounding rock is revealed.

Improvement of Field Assessment List for Slope-stability Estimation (국내외 급경사지 평가표 분석을 통한 개선방안 연구)

  • Son, Young-Jin;Park, Dug-Keun;Oh, Jeong-Rim;Song, Young-Karb
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.509-522
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    • 2010
  • There is a increasing trend in disaster occurrence due to steep-slope failures in urban area during typhoon and torrential rain season in Korea. The underlying hazards that cause slope failure are mainly linked with urbanization and industrialization. To minimize the disaster damages by slope failure, objective and unified evaluation approached are desired. Since currently available evaluation checklists are developed for specific purposed, there is a limitation to adapt those checklists for stability evaluation in natural terrain. This study proposes an improved evaluation checklist based on the comparison of previous checklists and applicability and feasibility are analyzed implementing field application.

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