• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.509-513
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• 2013

There are so many types of construction equipment. Excavator is one of typical construction equipment which is working under the tough and severe environments. It's important for engineers to design CE components by the vibration durability point of view. Traditionally, two typical vibration durability methods to verify the durability of components. The first is experimental method which is using the vibration durability test bench. But experimental approach on vibration durability is needed a lot of cost and time. The second is analytical method which is using the vibration durability analysis such as Dirlik, Stainberg, Lalanne and others methodologies. The one of main advantages on vibration durability analysis can reduce the cost and time. We present a vibration durability analysis process and methodology on the guardrail system in excavator.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.229-232
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• 2004

In order to ensure the construction of sustainable reinforced concrete structures, durability evaluation of RC structures before construction should be carried out. In this paper, a service life evaluation technique using a safety factor determined by a reliability theory for RC structures subjected to chloride attack is proposed. The life safety factor and the service life evaluation .proposed in this paper can be applied consistently for the durability evaluation of recently developed Korean standard specification for durability of concrete structures which be used effectively for the evaluation before construction and maintenance for RC structures under chloride attack.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.5 s.236
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• pp.655-662
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• 2005

This paper investigates the improvement of accuracy and fatigue life of the developed counter pressurized microcellular gears of polyacetal. It is shown that the fatigue life and operational characteristics of the counter pressurized microcellular gears are more improved than conventional injection molded plastic gears by the dynamic gear durability test. For the cases of test sea.5. conventional injection molded sea.5(SGea.) and counter pressurized microcellular gears(CGear) are manufactured. Durability test is performed on both conventional lnjection molded gears and counter pressurized microcellular gears. Accuracy variation and operational characteristics on fatigue life, wear and tooth surface temperature of CGear and Scear are compared and represented. Operational characteristics of the proposed counter pressurized microcellular gears show a good result in this research. The durability limit of counter pressurized microcellular gears is also obtained, and represented by a function of unit load as well as by a function off-factor.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.332-339
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• 2017

In the case of aged structures, the information of the structure is often lost after the completion of construction, and there is a great difficulty in predicting the durability life of the structure due to the lack of information on concrete formulations. In this study, the durability of concrete specimens was evaluated by various field and indoor test methods based on the core specimens collected from the field, and the durability life of the concrete structures was predicted by using the FEM analysis technique.As a result, the neutralization rate coefficient was $5.38E-6(cm^2/day)$ and the rate of progress was low. And the possibility of complex deterioration due to carbonation and salting was found to be very low.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.41-48
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• 2018

Carbonation is one of the major detrimental factors to the reinforced concrete structures owing to penetration of atmospheric CO2 through the micro pores, thereby it reduces the durability of the concrete. The maintenance periods and cost for concrete according to the coefficient variation of different finishing materials is documented in literature. However, it is required to carry out the systematic and well planned studies. Therefore, keeping them in mind, surface repair was carried out to the carbonated concrete and the maintenance cost was calculated to measure the durability life after repair with different variable. The deterministic and probabilistic methods were applied for durability and repair cost of the concrete. In the existing deterministic model, the cost of repair materials increases significantly when the concrete structure reaches its service life. In present study using a stochastic model, the maintenance period and cost was evaluated. According to obtained results, there was no significant difference in the number of maintenance of the coefficient variation. The initial durability has a great influence on the maintenance time and cost of the structure. Unlike the deterministic model, the probabilistic cost estimating model reduces the number of maintenance to the target service life expectancy.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.81-86
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• 2007

We suggest a design method for reducing the number of spot welds in the vehicle body in terms of durability. To reduce the number of spot welds, we use the DOE(Design of Experiments) analysis with two influence indices for the durability and the fatigue life of a spot weld itself. Through the suggested design method, we select spot welds that could be removed without serious reduction of durability of the whole model. We apply this new methodology to the BIW(Body In White) model of a vehicle by choosing some practical parts where durability-related point of view must be considered importantly by experience.

• International Journal of Automotive Technology
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• v.3 no.4
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• pp.129-135
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• 2002

Durability estimation of a prototype vehicle has traditionally relied heavily on accelerated durability tests using predefined proving grounds or rig tests using a road simulator. By use of those tests, it is very difficult to predict durability failures in actual service environments. This motivated the development of an integrated CAE (Computer Aided Engineering) methodology for the durability estimation of a prototype vehicle in actual service environments. Since expensive computational costs such as computation time and hardware resources are required for a full vehicle simulation in those environments with a very long span of event time, the conventional CAE methodologies have little feasibility. An efficient computational methodology for durability estimations is applied with theoretical developments. The effectiveness of the proposed methodology is shown by the comparison of results of the typical actual service environment such as the city mode with those of the typical accelerated durability test over the Belgian road.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.161-166
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• 1998

The concrete structures designed and constructed by conventional design concept based on structural performance consideration show sometimes serious durability problem when the structures are exposed to aggressive environment. Because present design system focuses on the structure safety and considers durability indirectly by the concrete mix design and cover depth, the durability of concrete structure cannot be ensured. As the first step to develope the durability design for concrete structure, durability index which represents internal concrete resistance and environment index which represents external environmental exposure are derived quantitatively. In the next step, the durability design system is developed by checking durability limit state with computed two indexes under service life condition by considering of the reliability of structure. Finally, the proposed system is verified with a model problem.

• Journal of Applied Reliability
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• v.16 no.2
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• pp.125-133
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• 2016

Purpose: The purpose of this study is to evaluate durability of platform safety step system in railway. Method: We performed finite element analysis & durability analysis of platform safety step system with VPD (Virtual Product Development) techniques and examined the durability standard & qualification life through the rig test during no failure test time in reliability qualification test. We continued to test 1 million cycles in KRS (Korea Railway Standard) for system's robust design performance. Result: FEM analysis results are 14.9MPa & 14.7MPa of pin-joint, pivot and durability analysis result is above 1 million cycles. we calculated theoretically no failure test time 855,000 cycles and through the 1 million cycles durability rig test in KRS standard we confirmed product quality. Conclusion: This platform safety step system was designed very safe in terms of a mechanical strength & durability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.208-213
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• 2008

In order to assess the reliability of the electronics control unit for vehicles, accelerated life test model and procedure are developed. By using this method, failure mechanism and life distribution are analyzed. The main results are as follows : i) the main failure mechanism is degradation failure that is, junction destruction of a semiconductor resin by high temperature. ii) the life distribution of the electronics control unit for vehicles is fitted well to Weibull life distribution and the accelerated life model of that is fitted well to Arrhenius model. iii) at the result of the life distribution, accelerated life test method is developed, and test time for life assessment will be shortened by 5,000 hours by this test method.