• 제목/요약/키워드: Field failure data analysis

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쉴드 TBM 터널에 적용 가능한 리스크 관리: II. 리스크 분석 방법 (Risk management applicable to shield TBM tunnel: II. Risk analysis methodology)

  • 현기창;민상윤;문준배;정경환;이인모
    • 한국터널지하공간학회 논문집
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    • 제14권6호
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    • pp.683-697
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    • 2012
  • 본 논문에서는 쉴드 TBM 터널에서 적용 가능한 리스크 분석 방법을 연구하였다. FTA 방법을 통해 리스크 아이템과 각각의 발생확률을 확인하고 AHP 방법을 통해 각각의 리스크 아이템의 영향도를 구하였다. 마지막으로 각각의 리스크 아이템의 리스크 레벨을 평가할 수 있었다. 개발된 방법을 EPB 쉴드 터널이 사용된 서울 지하철 현장에 적용하여 리스크 분석 결과가 현장 데이터에 부합하는 합리적 결과임을 검증하였다.

수치해석을 이용한 연약지반 성토 안정관리법 평가 (Evaluation of the Stability Management Methods for Embankments on Soft Clay Using Numerical Analysis)

  • 김종렬;박화정;황성원;강희복
    • 한국구조물진단유지관리공학회 논문집
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    • 제9권4호
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    • pp.202-208
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    • 2005
  • 현재 국내에서는 연약지반의 성토를 실시할 경우 성토사면의 안정을 관리하는데 있어 외국의 기준에 의존하는 경향이 있다. 현장에서 일반적으로 사용되고 있는 방법으로 곡선안정관리법, 변위속도안정관리기법, 직선안정관리기법, 성토하중관리법 등이 사용되고 있다. 본 연구는 수치해석을 통해 사면안정과 성토 안전관리법의 적용성을 검토하였다. 연구결과 곡선안정관리법은 다소 과대한 것으로 평가되었으며 직선안정관리법은 갑작스런 파괴의 위험이 있는 것으로 계측관리에 세심한 주의가 필요할 것으로 평가되었다. 그러나 변위속도 안정관리법은 과소평가되는 경향이 있으나 이는 현장의 불확실성을 고려할 때 현장적용에 적합한 것으로 평가되었다. 성토하중관리법은 파괴기준 값이 ${\Delta}_q/{\Delta}{\delta}$의 값보다 클 경우 안정하다고 평가하는 방법으로 실무에 적용할 경우에는 파괴기준 값의 산정에 어려움이 있다. 따라서 본 연구에서는 성토하중에 대한 ${\Delta}_q/{\Delta}{\delta}$값이 계속적인 증가 경향을 보일 경우 안정한 것으로 평가되었다.

국산훈련기 신뢰성기반 정비주기 연장방안 연구 (A Study for Maintenance Period Extension based on Reliability of Korea Trainer)

  • 조인탁;박종훈
    • 산업경영시스템학회지
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    • 제43권4호
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    • pp.123-132
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    • 2020
  • Currently, there are two types of trainer in Korea : basic and advanced. Both models have been in operation for more than 10 years, and compared to the early stage of operation, reliability has gradually improved and failure rates have also entered a trend of stabilization. Therefore, it is necessary to extend the maintenance period considering economic feasibility. This study investigates the three maintenance period calculation methods: NAVAIR 00-25-403 [17], DOD, U.S. [4], CERL and US Army [3], with intention to extend the maintenance period of the trainer from current 200 hours to 400 hours. In addition, the maintenance period was calculated by the three methods with actual operational data. Common standards and procedures were established to apply operational data to the existing maintenance period calculation methods, the required reliability indicators were derived, and the maintenance periods was calculated based on the results, additionally, a review on the field applicability of the three maintenance cycles was conducted. An on-site interviews were conducted with the calculation results, and 11 out of the 15 items were expected to be extended by 400 hours. It was suggested that the remaining 4 items could be extended to 400 hours by supplementing the inspection method through additional analysis such as functional analysis, inspection content verification, and site connection.

Fault Diagnosis of Roll Shape Under the Speed Variation in Hot Rolling Mill

  • Lee, Chang-Woo;Kang, Hyun-Kyoo;Shin, Kee-Hyun
    • Journal of Mechanical Science and Technology
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    • 제20권9호
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    • pp.1410-1417
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    • 2006
  • The metal processing system usually consists of various components such like motors, work rolls, backup rolls, idle rolls, sensors, etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is therefore necessary to diagnose the faults of the components to detect and prevent system failure. Especially, the defects in a work roll are critical to the quality of strip. It is especially difficult to detect faults of a roll by using the existing frequency analysis method if the speed of the roll is changing. In this study, a new diagnosis method for roll eccentricity under the roll speed changes was developed. The new method was induced from analyzing the rolling mechanism by using rolling force models, radius-speed relationship, and measured rolling force, etc. Simulation results by using the field data show that the proposed method is very useful.

Determination of tunnel support pressure under the pile tip using upper and lower bounds with a superimposed approach

  • Lee, Yong-Joo
    • Geomechanics and Engineering
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    • 제11권4호
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    • pp.587-605
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    • 2016
  • This study aimed to develop upper and lower bounds to predict the tunnel support pressure under the pile tip during the circular tunnel excavation. Most previous studies on the upper and lower bound methods were carried out for the single ground structures, e.g., retaining wall, foundation, ground anchor and tunnel, in the homogeneous ground conditions, since the pile-soil-tunnel interaction problem is very complicated and sophisticated to solve using those bound methods. Therefore, in the lower bound approach two appropriate stress fields were proposed for single pile and tunnel respectively, and then they were superimposed. In addition, based on the superimposition several failure mechanisms were proposed for the upper bound solution. Finally, these upper bound mechanisms were examined by shear strain data from the laboratory model test and numerical analysis using finite element method.

Numerical Fracture analysis of prestressed concrete beams

  • Rabczuk, Timon;Zi, Goangseup
    • International Journal of Concrete Structures and Materials
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    • 제2권2호
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    • pp.153-160
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    • 2008
  • Fracture of prestressed concrete beams is studied with a novel and robust three-dimensional meshfree method. The meshfree method describes the crack as a set of cohesive crack segments and avoids the representation of the crack surface. It is ideally suited for a large number of cracks. The crack is modeled by splitting particles into two particles on opposite sides of the crack segment and the shape functions of neighboring particles are modified in a way the discontinuous displacement field is captured appropriately. A simple, robust and efficient way to determine, on which side adjacent particles of the corresponding crack segment lies, is proposed. We will show that the method does not show any "mesh" orientation bias and captures complicated failure patterns of experimental data well.

차량화재 사고경향 및 사례분석 (Latest passenger vehicle fire trend and case study based on field investigation data)

  • 신준호;원유진;홍일민
    • 자동차안전학회지
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    • 제6권2호
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    • pp.67-71
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    • 2014
  • Based on the analysis of the actual passenger vehicle fire cases for recent four years (2010~2013), the passenger vehicle fire is increasing annually. Main root cause was analyzed as an electric problem as a 39%. Vehicle fire case by electric problem was mainly caused by use of Non-genuine part. Vehicle fire case by mechanical problem was mainly caused by various oil system maintenance. Vehicle fire case by smoking material was mainly caused by cigarette and disposal lighter. And external fire transition issue and towing mistake fire cases was also confirmed.

궤도차량용 휠의 내구성 예측을 위한 유한요소 해석 기법 연구 (Finite Element Analysis for the Prediction of Durability of Idler Wheel of Tracked Vehicle)

  • 이경호;노근래;이영신
    • 한국군사과학기술학회지
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    • 제12권5호
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    • pp.676-682
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    • 2009
  • The idler wheel installed at the front side of the newly developed tracked vehicle didn't meet the durability requirement by showing the crack failure near the jointed region at the wheel during the field test. To find the crack developing mechanism we constructed finite element model for the idler wheel representing the behavior of interface between each suspension units, material properties from the material test data and actual loading conditions. This paper shows a result that maximum von Mises stress near the bolt hole on the outer rim is higher than inner idler coressponding to the actual test result and that result was reversed by adopting the reinforcement outside of the outer rim.

${\cdot}$粘塑性構成式을 使用한 粘性土地盤의 變形解析 (An Analysis on the Deformation of Clayey Foundation Using Elasto-Viscoplastic Model)

  • 이문수
    • 한국농공학회지
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    • 제34권2호
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    • pp.60-72
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    • 1992
  • This study aims at predicting the behavior of saturated soft clayey foundation subjected to earth structure loads such as tidal dike, embankment etc. by using Biot's consolidation equation coupled with elasto-viscoplastic constitutive model. To validate the computer program developed b author, a case study was performed for the site of Kwang-yang steel works improved by sand drain, where since the beginning of the works, field measurements(settlement, lateral displacement and excess pore water pressure) had been accurately achieved. Comparisons between numerical results and observation values were carried out. The main results obtained are summarized as follows : 1. Settlement and lateral displacement between numerical and observation values show satisfactory accordance. 2. As for the exess pre water pressure, numerical results appear to be larger than observation values, which may be due to the existence of sand seams which were not found during soil investigation. 3. Useful data available for failure prediction of soft foundation can be secured by examining lateral displacement, settlement, exess pore water pressure and stress paths.

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현장 계측을 통한 자연사면에서의 강우 침투 특성 분석 (An analysis of rainfall infiltration characteristics on a natural slope from in-situ monitoring data)

  • 김웅구;장병욱;차경섭
    • 한국농공학회:학술대회논문집
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    • 한국농공학회 2005년도 학술발표논문집
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    • pp.375-380
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    • 2005
  • In Korea, most landslides are occurred during the rainy season from June to September and have a shallow failure plane parallel to the slope. For these types of rainfall-induced failures, the most important factors triggering slope unstability is not the increase of pore water pressure but the decrease of the matric suction of unsaturated soils by rainfall infiltration. So it is essential to landslide hazard assessment that defines the characteristics of infiltration in natural slopes. In this study, field measurements have been carried out in order to monitor in-situ volumetric water contents and ground water table, at several depths and locations on a natural slope. The results show that rainfall infiltration is correlated with antecedent water contents, rainfall intensity and total rainfall. The ground water table was varied sensitively by every rainfall event.

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