• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.212-221
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• 2022

In this paper, the evaluation procedure applying the limit state design method is studied to be consistent with the newly issued bridge design code in Korea. The live load factor for evaluation is proposed by calibrating for the target reliability index through reliability analysis. Using the actual bridge information collected for the representative bridge types in Korea, the load effects of the design live loads for the previous and current design codes are calculated and compared. The live load factor is calibrated through reliability analysis using the minimum required strength which equals to the load effect obtained for the example bridge. Bridge evaluation is performed by applying the live load factors for the evaluation level as well as design level. The load rating result is generally increased by applying the limit state design method compared to the previous design method and applying the proposed load factor for lowered target reliability index further increased the rating result.

• Proceedings of the Korean Reliability Society Conference
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• 2000.11a
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• pp.243-254
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• 2000

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.841-846
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• 2010

Reliability in electrical power system refers to normal operation for schedule time in some system that action consists. It means that if there is no contingency of electric power supply decrease or load curtailment, reliability of the system is high. In this paper, a method for evaluation of transmission capability is proposed considering reliability standards. Deterministic and probabilistic methods for evaluation of transmission capability has been studied. These researches considered uncertainty of system components or N-1 contingency only. However, the proposed method can inform customers and system operators more suitable transmission capability. Well-being method using state probabilities of system components proves to be a more effective method in this paper comparing with calculation of LOLE(Loss of Load Expectation). The length of calculation is shorter but it can give more practical information to the exact system operators. Well-being method is applied to IEEE-RTS 24bus system to evaluate reliability in case study. The result is compared with a existing way to evaluate reliability with LOLE and it shows that transmission capability connected with adjacent networks. This paper informs system operators and power suppliers of reliable information for operating power system.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1422-1431
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• 2015

The reliability of power system components can be affected by a numbers of factors such as the health level of components, external environment and operation environment of power systems. These factors also affect the electrical parameters of power system components for example the thermal capacity of a transmission element. The relationship of component reliability and power system is, therefore, a complex nonlinear function related to the above-mentioned factors. Traditional approaches for reliability assessment of power systems do not take the influence of these factors into account. The assessment results could not, therefore, reflect the short-term trend of the system reliability performance considering the influence of the key factors and provide the system dispatchers with enough information to make decent operational decisions. This paper discusses some of these important operational issues from the perspective of power system reliability. The discussions include operational reliability of power systems, reliability influence models for main performance parameters of components, time-varying reliability models of components, and a reliability assessment algorithm for power system operations considering the time-varying characteristic of various parameters. The significance of these discussions and applications of the proposed techniques are illustrated by case study results using the IEEE-RTS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.210-217
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• 2019

This research examines whether the evaluation index used Dream Start services operation evaluation has 'reliability in evaluation field and area' and 'whether there is discrimination according to evaluation index'. To do this, we conducted an empirical analysis based on the evaluation data of 126 municipal and provincial governments that received the 2018 Dream Start services operation evaluation. First, as a result of examining whether there is trust in each evaluation area, it was found that the reliability of the basic construction, integrated case management, and service operation field is higher than .6 and the lower evaluation indexes are the same Standards were met. However, the field of resource exploit and connectivity was not so reliable as the concept of sub-domains. Second, 'Are there discriminatory power according to the evaluation indexes?' The results showed that 18 of the 28 indicators were highly discriminative. On the other hand, 10 indicators showed low discrimination power.

• Journal of Applied Reliability
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• v.14 no.4
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• pp.236-242
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• 2014

Since permanent magnet coupling transfers power by magnetic force without contact, it has little shock, vibration, noise. In case of overload, it protects a pump or a motor which is relatively important by slipping internally. In this study, failure analysis and test evaluation on the permanent magnet coupling have been proposed and the process that reliability of the product improves through design improvement has been presented. And failure cause of typical failure case has been investigated and improvement plan has been presented. Finally, reliability improvement is established by analysis of the test results of before and after acceleration test.

• International Journal of Highway Engineering
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• v.18 no.4
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• pp.77-82
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• 2016

PURPOSES : This paper proposes a reliability index for the safety evaluation of freeway sections. It establishes a reliability index as a safety surrogate on freeways considering speeds and speed dispersions. METHODS : We collated values of design elements including radii, curve lengths, vertical slopes (absolute values), superelevations, and vertical slopes from seven freeway sections in Korea. We also collected data about driving speeds, traffic accidents, and their deviations. We established a reliability index using these variables. RESULTS : The average radii, curve lengths, and superelevations are highly correlated with the incidence of traffic accidents. Deviations in radius and curve lengths show an especially high correlation. The reliability index, derived from speed and speed dispersions of the seven freeway sections, also correlated highly with accidents with a correlation index of 0.63. CONCLUSIONS : Since the reliability index obtained from speed and speed dispersions are highly correlated with traffic accidents, we conclude that a reliability index can be a safety surrogate on freeways considering speeds and speed dispersions together in terms of design and operational levels.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.10a
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• pp.105-112
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• 1996

A practical approach for the assessment of system reliability-based safety and load carring capacity under vehicle traffics is proposed for the realistic evaluation of safety and rating of cable-stayed bridges. A partial event tree analysis model incorporating major critical failure paths is suggested as a practical tool for the system reliability analysis and system reliability-based capacity rating. The proposed approach for the system reliability analysis and system reliability-based rating is applied to the safety assessment of the Jindo Bridge which is one of two existing cable-stayed bridges in Korea. The results of analyses at the system level based on the system reliability are compared with those at the element level.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.59-62
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• 2001

Reliability engineering is regarded as the major and important roll for all industry. And advanced manufacturing systems with high speed and intelligent have been developing for the betterment of machining ability. In this study, we have systemized evaluation of reliability for machinery system. We proposed the reliability assessment and design review method using analyzing critical units of high speed and intelligent machine system. In addition, we have not only designed and developed test bed system for acquiring reliability data, but also apply QFD technique for satisfying quality function which is provided in design phase. From this study, we will expect to guide and introduce the reliability engineering in developing and processing phase of high quality product.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.16-23
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• 2006

Recently the design of multi-stage gear drive is being highly concerned. Until now, since the researches of gear drive are focused on the design for satisfying safety factor, the reliability evaluation of multi-stage gear drive is not included. In this paper, the life and reliability models of multi-stage gear drive are proposed using methods of probability and statistics. The life and reliability of the multi-stage gear drive have been evaluated, which is based on the life and reliability of each stage gear drive. The pinion and gear lives of each stage are calculated using the Lundberg-Palmgren theory and the Weibull failure distribution. These lives are combined using methods of probability and statistics to produce a life and reliability model of multi-stage gear drive.