• 한국안전학회지
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• 제34권5호
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• pp.103-110
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• 2019

In order to reduce the accidents occurring at construction sites, it is necessary to approach with harmonious measures considering various aspects such as systems, training, facilities, and protection equipments. Suggestion of safe construction method can be a good alternative. In the previous study, the half-depth precast deck with RC rib panel was proposed as an alternative method for safe bridge deck construction, and the performance required by the design code was verified through a four-point bending test. But the actual bridge deck is subjected to the repetitive action of the wheel load rather than the bending condition due to the four-point load. In this study, fatigue test was performed by repeating the wheel load $2{\times}10^6$ cycles to verify the safety of the half-depth precast deck with RC rib panel under actual conditions. As a result, fatigue effect due to repetition of wheel load was not significant in terms of serviceability such as crack width and deflection. In the residual strength test conducted after the fatigue test, the half-depth precast deck with RC rib panel failed by punching shear which is typical failure mode of bridge decks and the residual strength was similar to the punching strength of the RC and PSC bridge decks in spite of the fatigue effects.

• 대한안전경영과학회지
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• 제16권1호
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• pp.101-108
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• 2014

This study highlights the theme of human error of train drivers, conducting empirical analysis on the relationship between emergency stress, psychological fatigue, safety behavior, and accident. The hypothetical test results based on questionnaires received from 223 train drivers working at A subway firm indicate that emergency stress shows a significant positive effect on psychological fatigue, which in turn shows a significant negative influence on safety behavior. And safety behavior is shown having a significant negative relationship with accident. These results suggest the necessity of corporate-level approaches to depict the drastic causes of drivers' emergency stress, and to effectively manage this stress, as well as the necessity of making effort to enhance safety behavior, and to prevent or reduce accidents.

• 한국철도학회논문집
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• 제8권5호
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• pp.419-424
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• 2005

This paper has performed fatigue and nondestructive test of bogie frame for Korean tilting train. Before the fatigue test, static tests were carried out. From the test, the structural safety was investigated using Goodman diagram. After the static test, the fatigue test were conducted under tilting load conditions. The fatigue test was conducted for $10{\times}10^6$ cycles. During the fatigue test, the nondestructive tests using magnetic particle and liquid penetrant were performed at $6{\times}10^6$ cycle and $10{\times}10^6$cycle. From the crack detection tests, it was known that there was no fatigue crack in the bogie frame.

• 한국안전학회지
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• 제15권1호
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• pp.132-139
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• 2000

In this study, the fatigue life assessments of steel railway bridge in Japan National Railway were carried out. This railway bridge has been under in service from 1957, and fatigue damages were occurred at bead toe of upper part of vertical stiffeners of stringers, bead toes of scallop in lower part of vertical stiffeners in stringers and crossings of cross beams and stringers. From this study, a series of field tests were carried out by stress history measurement about above mentioned points. And as a results of stress histogram analysis, cummulative fatigue damage rate and fatigue life of these members should be calculate quantitatively. And from this estimation technique, cummulative fatigue damage rate and fatigue life of this railway bridge were strongly affected in passing tonage every year and the histories of live load.

• 한국안전학회지
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• 제11권2호
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• pp.3-8
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• 1996

Fatigue fracture is the cyclic fracture phenomena at a very small local area near a crack tip. Therefore, the detailed quantitative experimental analysis about local cyclic strain distribution near a crack tip is prerequisite In order to make an effective parameter able to account for fatigue fracture problems. However, there are few reports on detailed quantitative experimental analysis of a local cyclic strain distribution near a crack tip, because of experimental difficulties. In this study, the distribution of local fatigue strains near a fatigue crack tip was in detail studied using by fine dot grid strain measurement method. From these results, a single parameter, which characterizes local fatigue strain field, was proposed. In addition, this parameter was applied to evaluate the fatigue crack propagation rate.

• 대한기계학회논문집A
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• 제37권7호
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• pp.945-951
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• 2013

본 논문은 도시형 자기부상열차에 사용되는 대차프레임의 피로강도를 평가하는 방법을 제안하였다. 가상의 하중 시나리오로부터 구조해석을 수행하여 응력해석결과를 Goodman 선도상의 피로한계선도와 비교하였으며, UIC 규격에 적용되는 3단계의 피로조건을 적용하여 피로누적손상도(cumulative fatigue damge, D)를 계산하였다. 피로해석결과, Goodman 선도상에서 대차 프레임 사용소재인 A6005 알루미늄 합금 Butt 용접부의 피로한계선도를 초과하지 않았다. 가장 높은 피로손상도는 캐스팅 블록 및 전자석 폴 연결부로서 $1{\times}10^7$ cycles 기준으로 D=0.808로 계산되어 파손기준을 초과하지 않음을 확인하였다. 피로해석과 동일 조건으로 실시된 수직, 좌우, 전후 방향의 피로시험에서 대차 프레임의 어느 위치에서도 균열이 발생되지 않았으며, 이는 피로안전측으로 계산된 해석결과와 부합되는 결과이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.394-397
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• 2006

For checking fatigue safety and endurance of precast concrete deck and loop joint system in the steel plate girder composite bridge, the test composite bridge model was made for the fatigue experiment by the wheel load machine. The fatigue tests of 1,000,000 cycles were implemented according to wheel load condition of DB24 rear axle of Korea Highway Design Code. From the test results, the loop joint system for the precast deck has a sufficient flexural capacity. Although a little lower longitudinal continuity capacity is evaluated than general sound cast-in-place RC bridge deck, there is no problem about the safety. The overall fatigue level of safety defined by the code is satisfied.

• International Journal of Safety
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• 제9권1호
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• pp.12-20
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• 2010

In this study, a series of random field test and dynamic analysis in the time domain were carried out in order to find in the reason of fatigue damage of the main and the secondary members in the 3-span continuous steel plate girder railway bridge being under in service over 60 years. From the measured and the analyzed results, the stress distribution patterns were investigated for the members with fatigue damage. In addition, global and local numerical stress analysis was performed for the members damaged severely by corrosion, to estimate variation of the distribution by corrosion. Finally, a reasonable cut-off ratio in the steel plate railway bridge will be proposed by analyzing the equivalent stress ranges according the ratio.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 제7회 압연 심포지엄
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• pp.23-26
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• 2009

The purpose of this study is to investigate the fatigue safety and deformation of housing in plate rolling process. For this, we carried out 3-dimensional FEM analysis for housing considering design variations of housing structure. It showed that the housing with rounds under a column is benefits to control thickness accuracy of rolled material, due to smaller elastic deformation and maximum effective stress. Also, we calculated the fatigue safety factors, the ratios of the pulsating equivalent fatigue limit to the maximum tensile stresses analyzed using the equipment force and normal rolling force.

• 한국안전학회지
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• 제10권2호
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• pp.10-16
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• 1995

In estimating the fatigue data, only the uniform safety rate has been applied so far However, since more reasonable design concepts such as machine structures or subsidiary materials will be required in the future, the importance of a statistical estimation method for fatigue data is being highlighted. With such basic conception in mind, this study was aimed at critically discussing the interval estimation method which has been applied using the classical statistics thus far It was conceived that this conventional method would result in the estimation of the unstable side from the viewpoint of the likelihood Interval estimation method. In this regard, this study aimed at estimating the fatigue strength through the likelihood interval estimation method comparing it with the conventional interval estimation method would result in the estimation of the unstable side from the viewpoint of the likelihood interval estimation method. One of the methods using the likelihood for estimation data is the Bayes method. Based on this theory, statistical estimations were positivly applied, and thereupon, the fatigue data were estimated.