• Geomechanics and Engineering
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• 제11권2호
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• pp.253-267
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• 2016

The stability of surrounding rock will be poor when the tunnel is excavated through nearly horizontal stratum. In this paper, the instability mechanism of local nearly horizontal stratum in super-large section and deep buried tunnel is revealed by the analysis of the macro failure and micro fracture. A structural model is proposed to explain the mechanics of surrounding rock collapse under the action of stress redistribution and shed light on the macroscopic analytical approach of the stability of surrounding rock. Then, some highly effective formulas applied in the tunnel engineering are developed according to the theory of mixed-mode micro fracture. And well-documented field case is made to demonstrate the effectiveness and accuracy of the proposed analytical methods of mixed-mode fracture. Meanwhile, in order to make the more accurate judgment about yield failure of rock mass, a series of comprehensive failure criteria are formed. In addition, the relationship between the nonlinear failure criterion and $K_I$ and $K_{II}$ of micro fracture is established to make the surrounding rock failure criterion more comprehensive and accurate. Further, the influence of the parameters related to the tension-shear mixed-mode fracture and compression-shear mixed-mode fracture on the propagation of rock crack is analyzed. Results show that ${\sigma}_3$ changes linearly with the change of ${\sigma}_1$. And the change rate is related to ${\beta}$, angle between the cracks and ${\sigma}_1$. The proposed simple analytical approach is economical and efficient, and suitable for the analysis of local nearly horizontal stratum in super-large section and deep buried tunnel.

• 한국지반신소재학회논문집
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• 제9권4호
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• pp.17-25
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• 2010

전통적인 보강토옹벽 설계에서의 안정성 검토는 내적 외적 안정으로 구분하여 평가하며, 내적 안정은 보강재의 인발, 파단를 대상으로 하고 외적 안정은 구조체의 침하, 전도, 활동을 대상으로 한다. 최근 지반물성과 해석모델이 갖는 고유 불확실성을 최소화하기 위하여 신뢰성해석이 개발되어져 왔다. 본 연구에서는 내적 외적 안정이라고 정의되는 다양한 파괴모드에 대한 동시 파괴확률의 산정할 수 있도록 체계 신뢰성해석을 제안하였다. 단일구간 모드해법을 적용함에 의해 여러 안정해석에 대한 파괴모드를 통합하여 보강토옹벽 전체 시스템의 안정성을 평가할 수 있도록 하였다. 동시 파괴확률을 이용하면 대상으로 하는 안정해석모델과 파괴형상 및 파괴확률을 복합적으로 고려할 수 있기 때문에 개선된 안전성을 확보할 수 있을 것으로 판단되며, 안정해석모델별로 여러 지표를 이용하여 평가되었던 보강토옹벽의 설계를 대표 지표를 통하여 평가할 수 있다.

• 한국자동차공학회논문집
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• 제21권4호
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• pp.166-173
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• 2013

An aluminum suspension corner module is widely used in high class passenger cars to reduce vehicle weight and improve fuel economy. According to the change of material and suspension type, the evaluation of the static strength and failure mode of the corner module is important. In this study, static strength and failure mode analysis of aluminium multi-link suspension corner module is presented. Static strength test system is designed and static failure mode tests of the corner module are carried out in longitudinal, lateral, and vertical direction. From the resuls of the tests we found that the failure modes are different compare to those of the steel corner module. The static failure modes and load-displacement curves of this study will be used as a guidance in design of a passenger car aluminium multi-link suspension corner module.

• Coupled systems mechanics
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• 제7권1호
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• pp.27-42
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• 2018

Behavior of soil is usually described with continuum type of failure models such as Mohr-Coulomb or Drucker-Prager model. The main advantage of these models is in a relatively simple and efficient way of predicting the main tendencies and overall behavior of soil in failure analysis of interest for engineering practice. However, the main shortcoming of these models is that they are not able to capture post-peak behavior of soil nor the corresponding failure modes under extreme loading. In this paper we will significantly improve on this state-of-the-art. In particular, we propose the use of a discrete beam lattice model to provide a sharp prediction of inelastic response and failure mechanisms in coupled soil-foundation systems. In the discrete beam lattice model used in this paper, soil is meshed with one-dimensional Timoshenko beam finite elements with embedded strong discontinuities in axial and transverse direction capable of representing crack propagation in mode I and mode II. Mode I relates to crack opening, and mode II relates to crack sliding. To take into account material heterogeneities, we determine fracture limits for each Timoshenko beam with Gaussian random distribution. We compare the results obtained using the discrete beam lattice model against those obtained using the modified three-surface elasto-plastic cap model.

• 시스템엔지니어링학술지
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• 제18권1호
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• pp.46-57
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• 2022

In this paper, we proposed the DFMEA Implementation Method for safety design of Weapon System. First, we presented the process for DFMEA. And then, the case analysis of OOO missile was performed in accordance with the process presented. After defining the system requirements of OOO missile, failure definition scoring criteria was set. In order to clarify the definition of failure, the failure was classified into safety, reliability, maintainability and others. After performing the function analysis, the relationship matrix analysis was performed to identify the failure mode according to the function without omission. After clarifying the failure classification, mode of failure, cause of failure and effect were analyzed to calculate the severity, occurrence and detection values. After the action priority was judged, the recommended action according to the failure classification was identified for the determined action priority. The results of this study can be used as a relevant basis for the design reflection and resource re-allocation of stakeholders.

• 한국멀티미디어학회논문지
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• 제20권11호
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• pp.1793-1802
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• 2017

In the recent years, IT and Network Technology has rapidly advanced environment in accordance with the needs of the times, the usage of the smart learning service is increasing. Smart learning is extended from e-learning which is limited concept of space and place. This system can be easily exposed to the various security threats due to characteristic of wireless service system. Therefore, this paper proposes the improvement methods of smart learning system security by use of faults analysis methods such as the FTA(Fault Tree Analysis) and FMECA(Failure Mode Effects and Criticality Analysis) utilizing the consolidated analysis method which maximized advantage and minimized disadvantage of each technique.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권1호
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• pp.15-19
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• 2001

Current leakage is the major failure mode of semiconductor device characteristic failures. Conventionally, failures such as short circuit breaks and gate breakdowns have been analyzed and the detected causes have been reflected in the fabrication process. By using a wafer-level emission-leakage failure analysis method (in-line QC), we analyzed leakage mode failure, which is the major failure detected during the probe inspection process for LSIs, typically DRAMs and CMOS logic LSIs. We have thus developed a new technique that copes with the critical structural failures and random failures that directly affect probe yields.

• 한국정밀공학회지
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• 제26권9호
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• pp.96-102
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• 2009

In this study, performs analysis of the life of parallel opening type pneumatic chucks that are usually applied in the factory automation line. Pneumatic chucks have complicated failure cause because they are organized as a complex of various elements. Therefore, we analyzed the main failure mode of pneumatic chuck, and then performed life test and performance test according to the international standards. On the basis of these processes, shape parameter of pneumatic chuk is proposed that is the main factor for the calculation of zero failure test time for the reliability of pneumatic chuck and their data analysis of life distribution.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.435-439
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• 2002

In view of reliability assessment, the failure mode analysis by performance tests for machine tools is researched in this study. First, the error analysis with circular movement test data is studied. The various errors and their origins are analyzed by the error equations and then related parts and failure modes are investigated. Second, This paper deals with analysis of vibration testing for machine tools spindle. The various frequency components are classified by fourier transform and order analysis. The simple measuring devices and web-based analysis programs for each test are also developed.

• 한국소음진동공학회논문집
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• 제21권3호
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• pp.241-247
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• 2011

Although intensive development continues on innovative sensor systems, there is still considerable uncertainty in deciding on the number of sensors required and their locations in order to obtain adequate information on structural behavior. This paper is concerned with the sensor locations on a beam-structure for prognostic structural health monitoring. The purpose of this study is to investigate how to determine optimal sensor placement(OSP) from the sensitivity information of a known failure mode. The sensitivity of the forced vibration response of a beam to the variation of stiffness due to a crack is calculated analytically and used to determine the optimal sensor locations for the specified failure mode. The results of this method compared with the results of different OSP methods. The results have shown that the proposed method on optimal sensor placement is very effective in structural health monitoring.