• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.116-118
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• 2003

This paper describes a Accelerated Life Test (ALT) with the electrical contact erosion suitable to the evaluations of high-reliability and durability devices such as magnetic contactor. Recently, an electrical devices company was interested in accelerated life test (ALT), the product liability (PL) and the short-term testing model of electrical life test (ELT). In order to estimate a model for testing fee and period, need to the statistical analysis method with the acceleration factor(AF). Usually customer/manufacturer regard their device failure to the over-current or heavy duty condition, while devices view shape of contact erosion owing to operational duty problem. In this paper, additional method of evaluation estimated the operated cycles by weight of contact erosion with a used of regression analysis by MINITAB.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.188-193
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• 2007

Magnetic contactors (MCs) are widely used in industrial equipment such as elevators, cranes and factory control rooms in order to close and open the control circuits. The reliability of MCs mainly depend on mechanical durability and international standards such as IEC 60947-4-1, which stipulates the testing method for MCs. Testing time, however, is so long in usual cases that a method of reducing testing time is required. Therefore, a temperature and voltage-accelerated life testing (ALT) method has been developed to reduce the testing time in this work. The accelerated life test data are analyzed and acceleration factors (AFs) are provided.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.296-302
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• 2019

In this study, a basic durability assessment was performed by selecting the main part of a trial product of a shale shaker, which is one of components for a mud circular system. For a preliminary durability assessment, it was assumed that the lifetime of the bearing for the vibrator motor and the stiffness of the support spring are affected by the vibration when the motor operates continuously. In the case of the motor, the initial p-p level was 0.72 g, but after 100 hours of operation, the p-p level was rapidly increased to 1.26 g. Bearing defects could be estimated through ball defect frequency analysis. In the case of the spring, the stiffness of the spring was reduced by approximately 3.78% at the end of 2,000 hours of the fatigue-durability test by applying excitation conditions to shale shaker body. In the future, we will analyze the influence of the particle removal efficiency of the shale shaker.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.133-134
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• 2008

This paper describes a testing method to assess the reliability of the epoxy bushing used for the vacuum circuit breaker(VCB). Especially, in order to show the long-term durability of epoxy bushing in a short testing duration, the extremely accelerated electric stress applying test plan was adopted.

• Journal of Auto-vehicle Safety Association
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• v.11 no.4
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• pp.22-27
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• 2019

In this paper, the vibration load and analysis results for automotive battery supporter were performed to provide efficient vibration tolerance performance prediction methods for single-product vibration tolerance testing, and the major influencing factors and considerations for setting up single-unit vibration tolerance tests were reviewed. A common applicable standard load was applied to efficiently predict the performance of single-unit vibrations through the frequency response analysis technique. The results similar to test results can be predicted by checking vulnerable parts of the vehicle components for vibration loads and applying scale factor to standard loads. In addition, it was confirmed that the test conditions with a frequency generating the same durability severity as the endurance test are needed for accurate prediction of the durability of the single-unit vibration tolerance test conditions, and the acceleration and frequency with the conditions that there is no significant nonlinear phenomena in the vibration system are established during the single-unit vibration tolerance test conditions.

• Journal of Applied Reliability
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• v.14 no.3
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• pp.203-207
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• 2014

Electrodeless lamp is famous for its long life. But its reliability is dependent not only on electrodes but also on materials and structures. To evaluate end product's reliability, we studied high temperature durability by $60^{\circ}C$, $75^{\circ}C$ and $90^{\circ}C$ temperature tests, and predicted failure times by an exponential model through regression analysis. However, the test showed that temperature does not affect degradation of electrodeless lamps. Their luminous outputs degrade during the early time of the test (till 250 hours) and then converge to a saturation points. Also, '410nm ~ 530nm' spectrum degrades more than other spectra.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.65-74
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• 2013

PURPOSES: This study is to evaluate the dynamic modulus changes of permeable asphalt mixtures by using non-destructive impact testing method and to compare the dynamic moduli of permeable asphalt mixtures through repeated freezing and thawing conditions. METHODS: For the study, non-destructive impact testing method is used in order to obtain dynamic modulus of asphalt specimen and to confirm the change of dynamic modulus before and after freezing and thawing conditions. RESULTS : This study has shown that the dynamic moduli of asphalt concrete specimens consisting of 10%, 15% and 20% porosity are reduced by 11.851%, 1.9564%, 24.593% after freezing and thawing cycles. CONCLUSIONS : Non-destructive impact testing method is very useful and has repeatability. Specimen with 15% porosity has high durability than others.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.206-211
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• 2000

The accelerated testing technique using the equivalent load condition plays an important part in development process. However, in the industrial field, the theoretical background and advantages of this accelerated testing technique have been lack of understanding. Because the environmental durability condition forms the foundation of the accelerated testing technique, it is important to analyze the loading components and damage in service environment. In this work, we present the theoretical background and process for accelerated testing, and introduce our accelerated equivalent load analysis program. We developed the GUI program, and the user can easily obtain the result by selecting the program module.

• Computers and Concrete
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• v.6 no.4
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• pp.269-280
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• 2009

In this paper an experimental study of the influence of hot springs curing upon concrete properties was carried out. The primary variables of the investigation include water-to-binder ratio (W/B), pozzolanic material content and curing condition. Three types of hot springs, in the range $40-90^{\circ}C$, derived from different regions in Taiwan were adopted for laboratory testing of concrete curing. In addition, to compare with the laboratory results, compressive strength and durability of practical concrete were conducted in a tunnel construction site. The experimental results indicate that when concrete comprising pozzolanic materials was cured by a hot spring with high temperature, its compressive strength increased rapidly in the early ages due to high temperature and chloride ions. In the later ages, the trend of strength development decreased obviously and the strength was even lower than that of the standard cured one. The results of durability test show that concrete containing 30-40% Portland cement replacement by pozzolanic materials and with W/B lower than 0.5 was cured in a hot spring environment, then it had sufficient durability to prevent steel corrosion. Similar to the laboratory results, the cast-inplace concrete in a hot spring had a compressive strength growing rapidly at the earlier age and slowly at the later age. The results of electric resistance and permeability tests also show that concrete in a hot spring had higher durability than those cured in air. In addition, there was no neutralization reaction being observed after the 360-day neutralization test. This study demonstrates that the concrete with enough compressive strength and durability is suitable for the cast-in-place structure being used in hot spring areas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.66-72
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• 2019

To improve ride quality and running stability of high speed train(HST), it is important that connection between coaches adopts the articulated bogies by using a gangway ring, unlike the conventional independent bogies assembled with car bodies. Although the gangway ring should be ensured absolute safety against passenger movement between coaches during train operation, there is still a lack of quantitative durability criteria of that. Therefore, in order to improve the passenger safety of HST, it is important to study the test requirements on durability evaluation for the ring. In this study, seven mixed loading cases were derived from the triaxial loading(vertical/lateral/longitudinal) modes. The safety factor of each component is at least 2.4 or more from the results of the finite element analysis. In addition, fatigue safety was evaluated through durability analysis from the viewpoint of strain-life design. Durability tests for the gangway ring carried out a total of 10 million cycles in 4 phases load conditions. After the durability test, the defect of each component was investigated using nondestructive testing techniques.