• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.105-109
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• 2010

While numerous information services are provided on the Web as a core infrastructure of information society, semantic services using the Semantic Web technologies still stay deployed number and application range. This situation would be mainly originated from the failure of securing reliability to the user. Thus, this paper introduces an evaluation method for measuring reliabilities of the semantic services comparatively. To measure the reliability of the compared systems, the observer assesses 'precision in task performance' as a quantitative analysis and 'reliability of expectation-result' as a qualitative analysis described by the test persons. On the other hand, the test person should rate the functional reliability and reliability of the served information on the vector graph by himself with a scale from 0 to 5. Experimental results show that assessment by the observer is very similar to rating value by test persons, and that the accuracy of the served information has a close effect on the functional reliability. Through this paper, we can verify the essential factors for evaluating the reliability of semantic service systems. These are functional reliability and reliability of served information resulting from function execution. In particular, it has been proven that the reliability of the semantic information services largely influences the "Quality in Use" and therefore determines the major factors of the semantic service reliability.

• Journal of Power System Engineering
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• v.16 no.3
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• pp.44-50
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• 2012

The reliability qualification test is essential in order to ensure the life time of the product under the normal operation conditions when a new product is developed. The reliability qualification test period has an important impact on the development time of new product. Therefore, some researches to reduce the test time of reliability qualification test have been actively studied. Generally, accelerated life test is well known as one method that can save the test time of the reliability qualification test. This test is conducted under the higher stress condition than normal condition. So we need to investigate what factor affects to the higher stress condition. This paper shows the relationship between the acceleration factor and reliability qualification test period. Especially, we focused on the method to obtain effective acceleration factors under the high temperature condition. Through some experiments for a refrigerator's compressor, we were able to confirm how to increase acceleration factors and how to reduce the reliability qualification test period with minimum samples.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.437-443
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• 2014

Engine is one of the most important parts in a rocket for completing its mission successfully. In this paper, we provide a methodology for estimating reliability and development cost of a liquid rocket engine newly developed. To estimate reliability, a baseline engine is selected considering factors whose effects on reliability are unquantifiable. Then reliability of a baseline engine is adjusted to reflect the effect of factors that can be modeled quantitatively. Using the previous Transcost engine cost expressed in terms of mass and the number of hot firing tests, the engine development cost is reexpressed in reliability and thrust requirements. Finally, a numerical example is given to illustrate the application of the methodology to a turbopump rocket engine using staged combustion cycle with LOX/LH2 propellant.

• Korean Journal of Construction Engineering and Management
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• v.13 no.3
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• pp.43-55
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• 2012

A methodology for BIM Quality Assurance in the construction industry is becoming increasingly an important issue to determine the reliability of BIM. However, the quality assurance of BIM is currently limited to check 3D models, such as clash detection and space layout while verification methods for disciplinary BIM results from structural engineering, mechanical engineering, and estimation do not exist yet. Particularly, in the BIM-based estimation mathematical equations to take off quantities are not clearly exposed so that the results are not quite accepted at practices. With the concept of reliability engineering defined in the manufacturing industry to improve reliability of outcomes of BIM-based quantity take-off, impacting factors that affect reliability of BIM-based quantity take-off were derived. It was found that the factors also include the modeling method and the features of a BIM tool. Therefore, this research aims to propose modeling and verification methods to improve reliability of BIM-based quantity take-off through the pilot test that was performed with commercial BIM tools and IFC-based BIM data.

• Proceedings of the Korean Society for Quality Management Conference
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• 2007.04a
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• pp.362-369
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• 2007

This study set the hypothesis to develop the method that was analysis and application of a reliability evaluation method of environmental material for the Computer, Color TV, Monitor, Microwave oven, Electric Refrigerator, Automobile parts, other goods. RoHS management and product reliability ensure method for the conservation of environment. Especially, this study emphasis on regulate export of the EU and North America that it's a environmental material problem. Therefore, this study emphasis on the application of a reliability ensure method of environmental material and the use of other parameter by environmental reliability test data. The result of this study is as follows. 1) There is relationship between regulate material and technical protecting system. 2) Characteristics of hazard material is operating a healthcare damage factor as well as regulate environmental factors.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.713-722
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• 2007

Design variables for suspension systems cannot always be realized in the actual suspension systems due to tolerances in manufacturing and assembly processes. In order to deal with these tolerances, design variables associated with kinematic configuration and compliance characteristics of suspensions are treated as random variables. The reliability of a design target with respect to a design variable is defined as the probability that the design target is in the acceptable design range for all possible values of the design variable. To compute reliability, the limit state, which is the boundary between the acceptable and unacceptable design, is expressed mathematically by a limit state function with value greater than 0 for acceptable design, and less than 0 for unacceptable design. Through reliability analysis, the acceptable range of design variables that satisfy a reliability target is specified. Furthermore, through sensitivity analysis, a general procedure for optimization of the design target with respect to the design variables has been established.

• Journal of the Korean Society of Systems Engineering
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• v.12 no.1
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• pp.105-112
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• 2016

An aircraft must be designed to minimize system failure rate for obtaining the aircraft safety, because the aircraft system failure causes a fatal accident. The safety of the aircraft system can be predicted by analyzing availability, reliability, and maintainability of the system. In this study, the reliability and the maintainability of the hydraulic system are analysed except the availability, and therefore the reliability and the maintainability analysis process and the results are presented for a helicopter hydraulic system. For prediction of the system reliability, the failure rate model presented in MIL-HDBK-217F is used, and MTBF is calculated by using the Part Stress Analysis Prediction and quality/temperature/environmental factors described in NPRD-95 and MIL-HDBK-338B. The maintainability is predicted by FMECA(Failure Mode, Effect & Criticality Analysis) based on MIL-STD-1629A.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.466-475
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• 2006

Reliability analysis between safety factor and reliability index for driven and bored pile load capacity was analyzed in this study. 0.1B, Chin, De Beer, and Davisson's methods were used for determining pile load capacity by using load-settlement curve from pile load test. Each method define ultimate, yield and allowable pile load capacities. LCPC method using CPT results was performed for comparing with results of pile load test. Based on FOSM analysis using load factors, it is obtained that reliability indices for ultimate pile load capacity were higher than those of yield and allowable condition. Present safety factor 2 for yield and allowable load capacities are not enough to satisfy target reliability index $2.0\sim2.5$. However, it is sufficient for ultimate pile load capacity using safety factor 3.

• Wind and Structures
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• v.24 no.3
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• pp.249-265
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• 2017

An efficient and accurate algorithm is proposed to estimate flutter safety factor of suspension bridges satisfying prescribed reliability levels. Uncertainties which arise from the basic wind speed at the bridge deck location, critical flutter velocity, the wind conversion factor from a scaled model to the prototype structure and the gust speed factor are incorporated. The proposed algorithm integrates the concepts of the inverse reliability method and the calculation method of the critical flutter velocity of suspension bridges. The unique feature of the proposed method is that it offers a tool for flutter safety assessment of suspension bridges, when the reliability level is specified as a target to be satisfied by the designer. Accuracy and efficiency of this method with reference to three example suspension bridges is studied and numerical results validate its superiority over conventional deterministic method. Finally, the effects of various parameters on the flutter safety factor of suspension bridges are also investigated.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.563-570
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• 2019

To analyze the seismic reliability of concrete rectangular liquid storage structures (CRLSSs), assuming that the wall thickness and internal liquid depth of CRLSSs are random variables, calculation models of CRLSSs are established by using the Monte Carlo finite element method (FEM). The principal stresses of the over-ground and buried CRLSSs are calculated under three rare fortification intensities, and the failure probabilities of CRLSSs are obtained. The results show that the seismic reliability increases with the increase of wall thickness, whereas it decreases with the increase of liquid depth. Between the two random factors, the seismic reliability of CRLSSs is more sensitive to the change in wall thickness. Compared with the over-ground CRLSS, the buried CRLSS has better reliability.