• Structural Monitoring and Maintenance
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• 제10권2호
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• pp.107-116
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• 2023

The health condition of of deep water high pile foundation is vital to the safe operation of bridges. However, pier foundations are vulnerable to damage in deep water due to exposure to sea torrents and corrosive environments over an extended period. In this paper, combined with aninvestigation and analysis of the typical damage characteristics of main pier group pile foundations, we study the safety monitoring and real-time early warning technology of the deep water high pile foundations, we propose an early warning index item and early warning threshold of deep water high pile foundation by utilizing a numerical simulation analysis and referring to domestic and foreign standards and literature. First, we combine the characteristics of structures and draw on more mature evaluation theories and experience in civil engineering-related fields such as dam and bridge engineering. Then, we establish a scheme consisting of a Early Warning Index Systemand evaluation model based on the analytic hierarchy process and constant weight evaluation method and apply the research results to a project based on the Jiashao bridge in Zhejiang province, China. Finally, we verify the rationality and reliability of the Early Warning Index Systemof the Deep Water High Pile Foundations.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1994년도 교수 연수회(환경)
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• pp.651-657
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• 1994

To assess quantitatively the association between benzene exposure and leukemia, we examined the mortality rate of a cohort with occupational exposure to benzene. Cumulative exposure for each cohort member was estimated from historical air-sampling data and, when no sampling data existed, from interpolation on the basis of existing data. The overall standardized mortality ratio (a measure of relative risk multiplied by 100) for leukemia was 337 (95 percent confidence interval, 154 to 641), and that for multiple myeloma was 409 (95 percent confidence interval, 110 to 1047). With stratification according to levels of cumulative exposure, the standardized mortality ratios for leukemia increased from 109 to 322, 1186, and 6637 with increases in cumulative benzene exposure from less than 40 parts per million-years (ppm-years), to 40 to 199, 200 to 399, and 400 or more. respectively. A cumulative benzene exposure of 400 ppm years is equivalent to a mean annual exposure of 10 ppm over a 40-year working lifetime; 10 ppm is the currently enforceable standard in the United States for occupational exposure to benzene. To examine the shape of the exposure-response relation, we performed a conditional logistic-regression analysis, in which 10 controls were matched to each cohort member with leukemia. From this model, it can be calculated that protection from benzene induced leukemia would increase exponentially with any reduction in the permissible exposure limit.

• 대한기계학회논문집B
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• 제37권12호
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• pp.1175-1183
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• 2013

전산유체역학 소프트웨어의 일부 개발자 및 사용자는 최신 전산유체역학 소프트웨어가 최소한 단상 원자로 안전문제는 타당하게 해석할 수 있을 것으로 생각하지만 계산 결과에는 여전히 제한성 및 불확실도가 존재한다. 현재 한국원자력안전기술원에서는 규제관점에서 원자로 안전문제에 대한 상용 전산유체역학 소프트웨어의 성능평가를 수행하고 있다. 본 연구에서는 축소 APR+ 원자로 내부유동 해석시다공성 모델을 적용한 상용 전산유체역학 소프트웨어의 예측 성능을 평가하기 위해 ANSYS CFX R.14 및 FLUENT R.14 에 탑재된 수치모델을 이용하여 계산을 수행하였다. 결론적으로 전산유체역학 소프트웨어에 따라 축소 APR+ 원자로 내부유동 분포는 국부적으로 차이가 발생하였다. 비록 제한된 수의 측정치로 인해 상용 전산유체역학 소프트웨어간 예측성능을 평가하기에는 다소 한계가 있으나 CFX R.14 가 FLUENT R.14 에 비해 상대적으로 타당한 예측결과를 제시하였다. 한편 적용된 차분법의 차이로 인해 동일한 격자에 대해 FLUENT R.14 가 CFX R.14 에 비해 상대적으로 많은 계산 메모리를 필요로 하였다. 따라서 대용량 병렬 계산시 가용한 계산 자원에 적합한 전산유체역학 소프트웨어가 선정되어야 한다.

• 대한안전경영과학회지
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• 제7권3호
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• pp.47-61
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• 2005

Many researchers have proved that risk measurement of information systems is a very effective tool for improving confidence of information systems. However, information system risk in Korea still includes many subjective judgements. This study deals with applying a quantitative model to improve risk measurement of information system quality. First of all, we have come up with solutions to improve the evaluation efficiency on risk measurement. We have merged the risk guidelines of COBIT and CMM, and developed a quantified evaluation scheme that call by risk point. We have proved the validity of this model by interviews with experts and by case studies.

• 한국안전학회지
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• 제28권2호
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• pp.78-83
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• 2013

The traffic culture index is used as a major index in evaluating the traffic safety services of local governments and also serve as important data for the planning and implementation of traffic safety services. However, as the traffic culture index gradually became a standard for comparison among local governments, in part, certain cases arose which questioned the grounds for selecting variables for the index and the validity of the index in terms of its influential relationship between evaluation items. This study analyzed the index's influential relationship by utilizing a PLS structural equation model based on the evaluation results of the 2011 traffic culture index. A variable-linking model was created which recognized the relativity taking into account of the indirect effects between latent variables and this model was proven to be a model suitable in explaining the traffic culture index with a 97.8% explanation power. It was found that traffic safety(0.530), driving behavior(0.527), pedestrian behavior(0.187) and vulnerable road users(0.147), in such order, had an effect on the traffic culture index. It was also found that human casualties due to traffic accidents under "traffic safety" and traffic light compliance rate under "driving behavior" had an important effect. The study showed that motor vehicle share in illegal parking in school zones did not have a valid explanation power regarding "vulnerable road users".

• 대한기계학회논문집A
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• 제39권10호
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• pp.1063-1068
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• 2015

본 논문에서는 도시철도차량의 타고오름 평가를 위한 충돌시뮬레이션 기법을 제안하였다. 시뮬레이션모델은 대차의 동적 거동을 표현하는 대차 동역학 모델과 붕괴거동을 표현할 수 있는 차체 유한요소 모델로 구성된다. 유럽 및 국내 충돌안전규정의 타고오름 평가를 위해 40 mm 오프셋 정면충돌 사고 각본에 따른 시뮬레이션을 수행하여 충돌 후 차체의 구조적 거동과 차체와 연계된 대차 모델의 동적 거등을 확인하였으며 타고오름 판단기준인 윤축의 상승거리로 타고오름을 평가하였다. 최종적으로 본 연구에서 제안한 시뮬레이션 기법을 적용하면 도시철도차량 충돌안전규정에 따라 충돌사고 시 타고오름에 대하여 평가할 수 있음을 확인하였다.

• 드라이브 ㆍ 컨트롤
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• 제19권3호
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• pp.39-46
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• 2022

In South Korea, to evaluate the rollover safety of domestic vehicles, the maximum slope angle of the vehicle is specified, which is verified by the rollover safety test of driving vehicles. However, the domestic rollover safety test is not suitable for buses, because the small amount of static stability factor (SSF) will invalidate the rollover experimental equation due to the high center of mass position of buses. To solve the above problems, a dynamic model of the bus is prepared with assumptions of mass and suspension spring properties. Subsequently, the maximum slope angle of the model was computed by using the simulation of multi-body dynamics, and the result was compared with actual test results to validate the dynamics model. Also, the rollover Fishhook (roll stability) test was conducted in the simulation for driving model. During the simulation, roll angle and roll rate were calculated to check if a rollover occurred. Through the rollover simulation of buses, the domestically regulated formula for rollover safety and the procedure of rollover test for driving vehicles are evaluated. The conclusion is that the present regulation of rollover test should be reconsidered for buses to ensure to get the valid results for rollover safety.

• Nuclear Engineering and Technology
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• 제32권5호
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• pp.465-476
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• 2000

In a nuclear power plant, steam generator tubes cover a major portion of the primary pressure-retaining boundary. Thus very conservative approaches have been taken in the light of steam generator tube integrity According to the present criteria, tubes wall-thinned in excess of 40% should be plugged whatever causes are. However, many analytical and experimental results have shown that no safety problems exist even with thickness reductions greater than 40%. The present criterion was developed about twenty years ago when wear and pitting were dominant causes for steam generator tube degradation. And it is based on tubes with single cracks regardless of the fact that the appearance of multiple cracks is more common in general. The objective of this study is to review the conservatism of the present plugging criteria of steam generator tubes and to propose a new coalescence model for two adjacent through-wall cracks existing in steam generator tubes. Using the existing failure models and experimental results, we reviewed the conservatism of the present plugging criteria. In order to verify the usefulness of the proposed new coalescence model, we performed finite element analysis and some parametric studies. Then, we developed a coalescence evaluation diagram.

• 자동차안전학회지
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• 제13권4호
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• pp.92-98
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• 2021

Recently hydrogen fuel cell buses have been deployed for the public transportations. In order to introduce buses fueled by hydrogen successfully, the research results of hydrogen bus safety should be discussed and investigated significantly. Especially, Korean government drives research in terms of various applications of hydrogen energy to replace the conventional fuel energy resources and to improve the safety evaluation. Thus it is necessary to examine vehicle crashworthiness under side impact loadings. This study was focused on the simulation result evaluation of full bus model and simplified bus model with hydrogen fuel tank module and mounting system located below floor structure due to the significance of bus side impact accidents. The finite element models of hydrogen bus, fuel tank system and side impact moving barrier were set up and simulation results reported model performance and result comparison of two side impact models. Computational results and research discussion showed the conceptual side impact framework to evaluate hydrogen bus crashworthiness.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1485-1486
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• 2011