• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.993-999
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• 2004

The estimation of fatigue life at the design stage of membrane type LNG tank is very important in order to arrive at feasible and cost effective solutions considering the total lifetime of the tank. In this study, the practical procedure of fatigue life prediction by use of cumulative damage factors based on Miner-Palmgren hypothesis and probability density function has been shown with the corner region of Gaz Transport Membrane type LNG tank being used as an example. In particular the parameters of Weibull distribution that determine the stress spectrum are discussed. The main results obtained from this study are as follows: 1. The recommended value for the shape parameter of Weibull distribution for the LNG tank is 1.1 in case of using the direct calculation method proposed in this study. 2. The calculated fatigue life is influenced by the shape parameter of Weibull distribution and stress block. The safe fatigue design can be achieved by using higher value of shape parameter and the stress blocks divided into more stress blocks.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.453-461
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• 1999

The estimation of fatigue life at the design stage is very important in order to arrive at feasible and cost effective solutions considering the total lifetime of the structure and machinery compo-nents. In this study the practical procedure of prediction of fatigue life by use of cumulative damage factors based on Miner-Palmgren hypothesis and probability density function is shown with a $135,000m^3$ LNG tank being used as an example. In particular the parameters of Weibull distribution taht determine the stress spectrum are dis-cussed. At the end some of uncertainties associated with fatigue life prediction are discussed. The main results obtained from this study are as follows: 1. The practical procedure of prediction of fatigue life by use of cumulative damage factors expressed in combination of probability density function and S-N data is proposed. 2. The calculated fatigue life is influenced by the shape parameter and stress block. The conser-vative fatigue design can be achieved when using higher value of shape parameter and the stress blocks divded into more stress blocks.

• Journal of Ocean Engineering and Technology
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• v.13 no.3 s.33
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• pp.29-35
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• 1999

At the design of Mark III membrane type LNG tank, an analytical and experimental approach on the fatigue strengths of membrane and its welds are very important in order to assist designers and surveyors. In this study, fatigue tests of lap weld of Mark III membrane type LNG tank were carried out and cumulative damage factor was calculated in order to estimate the fatigue life by probability density function and rule methods. It contained the following tests and reviews : 1) The fatigue tests of lap weld of stainless steel according to statistical testing method recommended by JSME, 2)Preparation of S-N curve for lap welds considering the statistical properties of the results of fatigue tests. 3) Procedure for estimating the initiation life of fatigue crack of lap welds under variable loads by the rule lf classification society and probability density function, 4) Guideline for inspection of lap welds fo membrane type LNG tank.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.542-548
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• 1997

In this study an evaluation method of fatigue strength of membrane type LNG tank is presented with FEM analysis and experimental approach of seam and raised edge welds. The study contains the following : l)FEM analysis of test specimens 2)Fatigue tests of seam and raised edge welds 3)Estimation of cumulative damage factor of the welds on the basis of safe life design concept complying with the rules of classification society 4)Review of the effect of mean stress on the fatigue strength 5)Modelling of fatigue life of the welds which is changeable by weld heights With the results obtained in this study, a model ${\Delta}{\delta}/h^2=0.13553\;{N_{f}}^{-0.3151}$ for seam and raised edge welds having a given weld height is proposed to be useful for designers and inspectors.

• Journal of Biosystems Engineering
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• v.34 no.5
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• pp.325-330
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• 2009

This study was performed to develop accelerated life test methods for agricultural tractor transmission receiving variable load. To acquire parameters for calculation of accelerated life test, endurance tests were performed under different torque conditions. Test results showed that the shape factor of Weibull distribution was 1.5 and fatigue damage exponent was 5.4. The calculated test time was 5,877 hours under the conditions of average life (MTBF) 3,000 hours and 90% reliability for one test sample. According to the linear cumulative damage rule, test time could be reduced using increased test load. Test time could be reduced by 252 hours when 1.2 times of the rated load compared with 0.67 times of the rated equivalent load calculated by load spectrum of the agricultural tractor. Calculated acceleration coefficient was 23.3.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.2
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• pp.66-70
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• 2016

Following the 2011 Fukushima Nuclear Power Plant accident, the IAEA has issued a revised version of the Nuclear Safety Standard for beyond design basis earthquake to consider the core meltdown accident. In Korea, relevant laws and regulations were also revised to consider beyond design basis earthquake to nuclear components. In this paper, CAV, an seismic damage factor that determines the restart of nuclear power plant after operating breakdown earthquake, is proposed for extension to the beyond design basis earthquake. For pipings not satisfying the beyond design basis earthquake condition, several evaluation methods are suggested, such as strain-based evaluation methods, simple nonlinear analysis method and cumulative damage evaluation method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.115-116
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• 2006

In these days, almost urban railway vehicle has been serviced under the random load application. But it is very important that fatigue lift prediction fur structures is major factor of safety. So do this, it is required that fatigue assessment method for cumulative damage approach while Korea domestic regulations only has endurance limit approach. With this endurance limit approach, fatigue lift prediction is impossible. In this research, it will be present that fatigue assessment for urban transit structure by using of cumulative damage approach method and related theories.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.1
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• pp.49-58
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• 1997

The membrane type LNG tank is non self-supporting tank which consists of both primary and secondary membrane supported through the insulation boxes by the adjacent hull struc¬ture. Although the membranes are not structural member. They are subject to periodical cyclic loads due to the thermal expansion and other expansions or contraction of membrane. At the design stage of the tank, an analytical and experimental approach on the fatigue strengths of membrane and its welds is necessary in order to assist the designer and the inpector. In this study the evaluation method of fatigue strength of membrane type LNG tank is pre¬sented with FEM analysis and fatigue test of lap welds and it contains the following:1) The fatigue tests and preparation of design S - N curve for lap welds 2) FEM analysis of test specimens 3) Estimation of cumulative damage factor of lap welds 4) Guideline for inspection of lap welds of membrane type LNG tank As the results of analytical and experimental approaches in this study, the evaluation method of fatigue strengths of membrane type LNG tank is proposed, which is expected to be useful for design and inspection of membrane type LNG tank.

• Structural Engineering and Mechanics
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• v.39 no.3
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• pp.411-425
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• 2011

This paper illustrates the results of a seismic vulnerability study aimed to derive the fragility curves for typical Algerian reinforced concrete bridge piers using an analytical approach. Fragility curves express the probability of exceeding a certain damage state for a given ground motion intensity (e.g., PGA). In this respect, a set of 41 worldwide accelerometer records from which, 21 Algerian strong motion records are included, have been used in a non-linear dynamic response analyses to assess the damage indices expressed in terms of the bridge displacement ductility, the ultimate ductility, the cyclic loading factor and the cumulative energy ductility. Combining the damage indices defined for 5 damage rank with the ground motion indices, the fragility curves for the bridge piers were derived assuming a lognormal distribution.

• Journal of the Korean association of regional geographers
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• v.20 no.4
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• pp.444-453
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• 2014

Inequality of environmental impact is forecast to deepen due to the damage of environmental risk by the interaction between environmental and social inequalities causing more harms to environmentally vulnerable population. This study assessed the integrated cumulative impact of Seoul using Environmental Health Screening Tool developed by Environmental Protection Agency of California. In order to screen vulnerable area to environmental health, 10 indexes have been selected according to the environmental burden of exposure to environment and public health effects, population characteristics of sensitive populations and socio-economic factors. As a result of assessment conducted on cumulative impact of Seoul for years 2009~2011 through Environmental Health Screening Tool, risk factor for districts of Gangseo and Gangnam of Seoul showed high - Gangseo area indicated high risk factor both in environmental burden and population characteristics, while Gangnam area appeared high in environmental burden. The result of survey will be able to suggest scientific basis to push through fair and effective environmental policy in consideration of environment vulnerable population.