• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.527-532
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• 2007

In this paper, we suggest those two design plans for power supply method of Hot Standby Sparing System; one is the plan using MTBF based on Constant Failure Rate, and the plan using Reliability Function is the other. Traditionally, RBD (Reliability Block Diagram) is used for reliability prediction which is required to meet any requirements before system operation. However, the system that has redundancy, such as Hot Standby Sparing System, Is not suitable for system reliability modeling using combination model, such as RBD. In this paper, therefore, we demonstrate that for redundancy controller, redundancy modeling design toward fault occurrence design is more effective to build up a system with higher reliability and achieve the effectiveness of loss cost due to maintenance and failure occurred in operation, rather than combinational modeling design.

• Journal of the Korean Wood Science and Technology
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• v.32 no.5
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• pp.45-50
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• 2004

Currently, structural design of wood structure has been based on ASD (Allowable Structural Design) in Korea. However, the results from this method was known as greater than real value because variations of materials and various conditions were not considered sufficiently. So the study about the design method with probabilistic approach is being performed to overcome this problem. And the standard design method of RBD (Reliability Based Design) has been established and applied. In this study, to apply this method on the domestic wood, the distribution property of the lumber and Glulam was analyzed from the previous report and the basis of the standardized design method was established as soft conversion method from allowable stress used in ASD into reference resistance used in RBD. And through the additional study about the sample size as a important factor to effect on soft conversion, condition to be required in more accurate conversion was evaluated.

• International Journal of Automotive Technology
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• v.6 no.3
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• pp.235-242
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• 2005

This study introduces the Reliability-Based Design Optimization (RBDO) to enhance the kinematic and compliance (K & C) characteristics of automotive suspension system. In previous studies, the deterministic optimization has been performed to enhance the K & C characteristics. Unfortunately, uncertainties in the real world have not been considered in the deterministic optimization. In the design of suspension system, design variables with the uncertainties, such as the bushing stiffness, have a great influence on the variation of the suspension performances. There is a need to quantify these uncertainties and to apply the RBDO to obtain the design, satisfying the target reliability level. In this research, design variables including uncertainties are dealt as random variables and reliability of the suspension performances, which are related the K & C characteristics, are quantified and the RBDO is performed. The RBD-optimum is compared with the deterministic optimum to verify the enhancement in reliability. Thus, the reliability of the suspension performances is estimated and the RBD-optimum, satisfying the target reliability level, is determined.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.4
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• pp.334-345
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• 1997

Reliability-based design approaches are needed for cylindrical shell structure whose design and operational experiences are few and which are subjected to external loads of random loads. In designing new type of structure, it is very difficult to evaluate the safety factors due to lack of previous design data and operational experience. To solve the above mentioned problem, much attention is being focussed on rational reliability based design approaches. This paper deals with weight-optional reliability-based design of cylindrical shell structure subjected to structural reliability constraints taking into account of the effect of local buckling and interactive behavior between local and global buckling. Present mentioned is compared with the exiting optional design method based only on safety factors. Numerical simulation reveals that the present method leads to lighter structure (4% reduction in weight compared to the existing optimal design) with the same reliability index. For larger structures with more number of structural members and possible failure modes, the present W0RBD procedure will be an efficient tool in designing cost-effective rationalized economic design.

• Geomechanics and Engineering
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• v.1 no.1
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• pp.17-34
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• 2009

There has been growing agreement that geotechnical reliability-based design (RBD) is necessary for establishing more advanced and integrated design system. In this study, resistance factors for LRFD pile design using CPT results were investigated for axially loaded driven piles. In order to address variability in design methodology, different CPT-based methods and load-settlement criteria, popular in practice, were selected and used for evaluation of resistance factors. A total of 32 data sets from 13 test sites were collected from the literature. In order to maintain the statistical consistency of the data sets, the characteristic pile load capacity was introduced in reliability analysis and evaluation of resistance factors. It was found that values of resistance factors considerably differ for different design methods, load-settlement criteria, and load capacity components. For the total resistance, resistance factors for LCPC method were higher than others, while those for Aoki-Velloso's and Philipponnat's methods were in similar ranges. In respect to load-settlement criteria, 0.1B and Chin's criteria produced higher resistance factors than DeBeer's and Davisson's criteria. Resistance factors for the base and shaft resistances were also presented and analyzed.

• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.95-104
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• 2002

In this study, a reliability-based design (RBD) procedure for determining design values fur anchored sheet pile wall is proposed considering overturning about the anchor point as the major failure mode. In this design procedure, the depth of embedment of the sheet pile wall is logically chosen in accordance with degrees of uncertainties of design input parameters using approximate probabilistic computation methods. These methods have been successfully used in the geotechnical engineering requiring neither understandings of complex probabilistic theories nor efforts to prepare more data. It was investigated that the design results by the proposed method were compatible with those by commonly used deterministic design methods. Additionally, in an effort to investigate the effects of changes in the degree of uncertainties of major design variables on the design results of the sheet pile wall, a sensitivity analysis was peformed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.56-67
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• 2006

The reliability and failure mode effect analysis are effective means to achieve efficient and cost-reduction design for satellite development. The failure rate of COTS (Commercial-Off-The-Shelf) parts required for reliability analysis is not usually provided from the manufacturer. Space environment factors based on empirical data obtained from MIL-HDBK-217F can be applicable to the reliability calculation. As a radiation environment factor, the occurrence rate of SEL (Single Event Latch-up) is additionally incorporated for the failure rate prediction. In this paper, the statistical reliability analysis method for low-cost small satellite using COTS parts is suggested. This statistical reliability analysis was applied to HAUSAT-2 small satellite whose electronic boxes are consisted of many COTS parts to calculate the system reliability at the end of design mission life.

• Journal of the Korea Society for Simulation
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• v.29 no.1
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• pp.31-38
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• 2020

Mission reliability is defined by the probability of accomplishing the requirements task that were targeted in product development, and in the case of combat systems, mission reliability is an important factor that will determine victory or defeat, unlike commercial equipment. The mission reliability of the existing domestic combat system was calculated by considering only the physical connections of the equipment involved in the mission performance, but as the equipment becomes increasingly sophisticated and complex, it is impossible to determine the mission relevance solely by physical connection. Thus, in this paper, improved mission reliability was calculated using SysML, the system design modeling language, by taking into account the functional connection as well as physical connection. Based on this research, we look forward that the mission reliability of the combat system that will be developed in the future will be used as a verification material.

• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.72-79
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• 2003

In reliability based design(RBD) method, the distribution characteristics of mechanical properties of material are basic input variable. Therefore, distribution type and parameters of mechanical properties should be determined accurately. Until now, the properties were derived from tests with small, clear specimens. However, the test conditions should emulate as nearly as possible the way in which the timber would be used in practice and the test results should, as closely as possible, reflect the structural end use conditions to which the timber products would be subjected. In this study, structural timbers (38mm by 140mm, 3.0m long) were graded by visual assessment of growth characteristics and defects. And then bending tests were conducted on 498 structural size timbers. For each grade, the distribution type and the parameters of mechanical properties were determined for each grade. For the determination of best-fit distribution type, comparing of square error between distribution types and KS test were conducted. Best-fit distribution type of bending strength(MOR) is weibull distribution for all grade. In case of MOE, normal distribution is best-fit.