• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.617-617
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• 1989

This paper deals with a fatigue life prediction of a surface crack based on the experimentally obtained relationship between surface crack length ratio $a/a_{f}$ and cycle ratio $N/N_{f}$ using micro computer. Firstly $a/a_{f}$-$N/N_{f}$ curves obtained from experimental tests, were assumed as three curves UC(the upper limit curve), LC(the lower limit curve) and MC(the middle curve), and these were utilized to predict the fatigue life. Comparing the calculated values which represent the characteristics of crack growth behaviors from the three assumed curves with the experimental ones, it has been found that in the stable crack growth region, they coincide reasonably well each other. And the differences between the fatigue lives obtained from the assumed curves and the experimental fatigue life did not exceed 20%. Using the characteristics of $a/a_{f}$-$N/N_{f}$ curves, it is possible to predict the da/dN-Kmax curves and the S-$N_{f}$ curves.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.108-117
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• 1989

This paper deals with a fatigue life prediction of a surface crack based on the experimentally obtained relationship between surface crack length ratio $a/a_{f}$ and cycle ratio $N/N_{f}$ using micro computer. Firstly $a/a_{f}$-$N/N_{f}$ curves obtained from experimental tests, were assumed as three curves UC(the upper limit curve), LC(the lower limit curve) and MC(the middle curve), and these were utilized to predict the fatigue life. Comparing the calculated values which represent the characteristics of crack growth behaviors from the three assumed curves with the experimental ones, it has been found that in the stable crack growth region, they coincide reasonably well each other. And the differences between the fatigue lives obtained from the assumed curves and the experimental fatigue life did not exceed 20%. Using the characteristics of $a/a_{f}$-$N/N_{f}$ curves, it is possible to predict the da/dN-Kmax curves and the S-$N_{f}$ curves.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1097-1103
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• 1988

This paper deals with surface crack behavior and the fatigue life prediction of notched specimens using the relation between surface crack length, a, and the cycle ratio, $N/N_{f}$. From the $a-N\;/\;N_{f}$ curves, UC(the upper limit curve), LC(the lower limit curve) and MC(the middle limit curve) were assumed and utilized to predict the fatigue life and crack growth rate. The data computed from the three assumed curves were compared with the experimental data. It has been found that in the stable crack growth region ($N/N_{f}=0.3-0.8$) fatigue life can be predicted within 20% errors. Using the characteristics of $a-N\;/\;N_{f}$ curve, it is possible to predict the $da/dN-K_{max}$ curve, the $da/dN-{\Delta}K_{{\varepsilon}_t}$ curve, and the $S-N_{f}$ curve.

• Journal of the Korean Society for Railway
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• v.8 no.3
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• pp.260-266
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• 2005

The deterioration of a shunting locomotive was characterized for the lifetime assessment. The locomotive has been used for shunting works in steel making processes, and in this investigation, various types of technical evaluation methods for the locomotive parts were employed to assess the current deterioration status and to provide important clue for lifetime prediction. Unlike other rolling stocks in railway applications, the diesel shunting locomotive is composed of major components such as diesel engine, transmission, gear box, brake system, electronic devices, etc., which cover more than 70 percent of the total price of the locomotive. Therefore, in this paper, each part of major components in the diesel locomotive was analyzed in terms of the degree of deterioration. The lift-cycle-cost (LCC) analysis was performed based on the maintenance and repair history as compared with economical cost to provide the cost-effective prediction, i.e., to assess either repair for reuse or putting the locomotive out of service based on cost-effective calculation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.162-163
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• 2014

Operation and maintenance stage consists the largest portion of project life cycle cost. Appropriate management and analysis of such stages have massive effect on the total project cost. The effective prediction of optimized repair period is one of main factors in ㅌ management. However, it has been analyzed that the prediction of appropriate repair period revealed limitations in reliability. Therefore, this study suggests a methodology of repair period prediction by dividing finished projects into similar groups with same properties to be compared with the target project using quantitative variables.

• Journal of Welding and Joining
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• v.27 no.6
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• pp.49-54
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• 2009

In this study, the numerical analysis model for fatigue life prediction of welded structures are presented. In order to evaluate the structural degradation of welded structures due to fatigue loading, continuum damage mechanics approach is applied. Damage evolution equation of welded structures under arbitrary fatigue loading is constructed as a unified plasticity-damage theory. Moreover, by integration of damage evolution equation regarding to stress amplitude and number of cycles, the simplified fatigue life prediction model is derived. The proposed model is compared with fatigue test results of T-joint welded structures to obtain its validation and usefulness. It is confirmed that the predicted fatigue life of T-joint welded structures are coincided well with the fatigue test results.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.285-290
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• 2004

Low cycle fatigue tests are performed on the Inconel 617 that be used for a hot gas casing. The relation between strain energy density and numbers of cycles to failure is examined in order to predict the low cycle fatigue life of Inconel 617. The life predicted by the strain energy method is found to coincide with experimental data and results obtained from the Coffin-Manson method. Also the cyclic behavior of Inconel 617 is characterized by cyclic hardening with increasing number of cycle at room temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.612-615
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• 2005

Low cycle fatigue tests are performed on the Incollel 617 that be used fur a hot gas casing. The relation between strain energy density and numbers of cycles to failure is examined in order to predict the low cycle fatigue life of Inconel 617. The life predicted by the strain energy method is found to coincide with experimental data and results obtained from the Coffin-Mansun method. Also the cyclic behavior of Inconel 617 is characterized by cyclic hardening with increasing number of cycle at room temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.199-208
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• 1997

A local strain approach was applied to an external single and double grooved C-shaped specimen in order to evaluate and predict the fatigue crack initiation life by using low cycle fatigue properties. The low cycle fatigue properties were determined from the strain-controlled fatigue tests using smooth cylindrical axial specimens. Fatigue crack initiation life was evaluated by a life prediction software, FALIPS, based on the local strain approach. The fatigue life was significantly influenced by the mean stress, and SWT parameter represented the fatigue life effectively. The predicted fatigue crack initiation life was then compared to the experimental fatigue life evaluated from the C-shaped fatigue test specimens. A good correlation was found between the experimental and predicted fatigue lives within factors of 2 and 4 for the single and double grooved C-shaped specimens respectively. Also, experimental fatigue life of the double grooved specimen was 10-12 times longer than that of the single grooved specimen.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.4
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• pp.416-422
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• 2006

Most of the existing statistical models of software manpower profile are based on the assumptions of the usage and development process. Therefore, there is no universally applicable estimation and prediction model. To develop a prediction model, this paper suggests the predictive filter as a prediction model for software manpower profile. Firs of all, we investigate the software manpower profile and we suggest the input-output of predictive filter and method for parameter determination. Then, its usefulness is empirically verified by analyzing the actual data obtained from the software projects. Based on the average relative prediction error and Pred(0.25), the suggested predictive filter is compared with other well-known statistical estimation models. As a result, the predictive filter generally has a simple structure and on the other hand, it adapts the software manpower profile very well.