• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.211-216
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• 2002

실제적인 문제에서 신뢰성 기반 최적 설계(RBDO)를 구현하기 위해서는 유한요소 모델을 해석하기 위한 상용 프로그램과 설계한 것에 대한 신뢰성을 산정할 수 있는 프로그램을 통합하고 최적화 알고리듬을 적용하여야 최적화를 수행하여야만 한다. 또한 최적화 과정에서 최적상태에서 제약조건이 비활성 영역에서 놓이게 되는 것을 방지하기 위해서 제약조건 최적화 문제를 비제약 조건 최적화 문제로 바꾸어 주는 장애 함수를 사용하여 최적화를 수행하였다. 그리고 이 방법론을 기존의 신뢰성기반 최적화 방법론, 즉 신뢰도지수 접근방법과 목표성능치 접근방법과의 비교를 하였다.

• Journal of Applied Reliability
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• v.11 no.1
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• pp.31-41
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• 2011

A strut mount is an important part of vehicles which reduces the vibration and the impact transmitted from the wheels while supporting a shock absorber and a coil spring. Rubber compounding, shape design, and process design technologies are important components to improve the functionality of a strut mount such as durability, static, dynamic, and torsional characteristics. Among them the rubber compounding technology is the key technology which dominates the quality of a strut mount. In this study a strut mount with high reliability has been developed by adopting new rubber compounding and improving the shape of the inner plate and the isolator. Through the tests for prototypes it has been shown that the durability has been improved more than 2.5 times, from about 60,000 cycles to about 160,000 cycles.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.224-229
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• 2010

This paper presents a reliability-based topology optimization (RBTO) using bi-directional evolutionary structural optimization (BESO). An actual design involves uncertain conditions such as material property, operational load and dimensional variation. Deterministic topology optimization (DTO) is obtained without considering of uncertainties related to the uncertainty parameters. However, the RBTO can consider the uncertainty variables because it has the probabilistic constraints. In this paper, the reliability index approach (RIA) is adopted to evaluate the probabilistic constraint. RBTO based on BESO starting from various design domains produces a similar optimal topology each other. Numerical examples are presented to compare the DTO with the RBTO.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.351-352
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• 2006

There are many methodologies fur doing analysis of system's reliability in early design stage. Among the methods, PRISM is, as compared to MIL-HDBK-217, a newly developed technology but not easy to use. Because PRISM provides models that predict a part failure rate and field database, called EPRD and NPRD that can be combined with prediction models. This paper presents some capabilities of the prediction models in PRISM and usability of EPRD and NPRD database in system level reliability prediction.

• Journal of Korean Society for Quality Management
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• v.4 no.1
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• pp.20-24
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• 1976

The higher develops the industrial techniques, the more reliability of mac hi nary, equipments and systems want the consumers. So, it is a key to succeed in the new-product development that the consumers can put reliance on the product to be made in the product design stage. This study intends to help the product designer and the system manager by presenting them better reliability prediction techniques. For this purpose, the author built some fundamental reliability system models. And then predict the system reliability by estimating the elemental component's failure rate ${\lambda}_i$, and proposed an evaluation model. And also, a system is wrong according to the component's characteristics' degradation, we must estimate the degradation failure rate (average and standard deviation). For this, the "Moment method" is used.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.10a
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• pp.85-90
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• 1990

Current steel pile foundation design is bared an WSD, but the reliability based design method is more rational than the WSD. For this reason, this study proposes a reliability Index of the pile foundation by LFD which is most common type of pile foundation, and also proposes the theoretical bases of nominal safety factors of stability analysis by introducing the reliability theory. The measured bearing capacity data are analyzed to the descriptive statistics and classified into the four models of uncorrelated -normal(UNNO), uncorrelated -nonnormal(UNNN), correlated -normal(CONO), and correlated nonnormal (CONN). This study presents the comparisons of reliability index and check points using the AFSOM with respect to the four models as well as BASIC program.

• Structural Engineering and Mechanics
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• v.45 no.2
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• pp.201-209
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• 2013

A new dynamic reliability analysis of structure under repeated random loads is proposed in this paper. The proposed method is developed based on the idea that the probability density of several times random loads can be derived from the probability density of single-time random load. The reliability prediction models of structure based on time responses under several times random loads with and without strength degradation are obtained by using the stress-strength interference theory and probability density evolution method. The resulting differential equations in the prediction models can be solved by using the forward finite difference method. Then, the probability density functions of strength redundancy of the structures can be obtained. Finally, the structural dynamic reliability can be calculated using integral method. The efficiency of the proposed method is demonstrated numerically through a speed reducer. The results have shown that the proposed method is practicable, feasible and gives reasonably accurate prediction.

• Steel and Composite Structures
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• v.25 no.1
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• pp.45-55
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• 2017

Stainless steel exhibits high ductility and strain hardening capacity in comparison with carbon steel widely used in constructions. To analyze the particular behaviour of stainless steel cover-plate joints, an experimental study was conducted. It showed large ductility and complex failure modes of the joints. A non-linear finite element model was developed to predict the main parameters influencing the behaviour of these joints. The results of this deterministic model allow us to built a meta-model by using the quadratic response surface method, in order to allow for efficient reliability analysis. This analysis is then applied to the assessment of design formulae in the currently used codes of practice. The reliability analysis has shown that the stainless steel joint design according to Eurocodes leads to much lower failure probabilities than the Eurocodes target reliability for carbon steel, which incites revising the resisting model evaluation and consequently reducing stainless steel joint costs. This approach can be used as a basis to evaluate a wide range of steel joints involving complex failure modes, particularly bearing failure.

• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.81-96
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• 2019

In this paper, a hybrid uncertain model is applied to system reliability based design optimization (RBDO) of trusses. All random variables are described by random distributions but some key distribution parameters of them which lack information are defined by variation intervals. For system RBDO of trusses, the first order reliability method, as well as monotonicity analysis and the branch and bound method, are utilized to determine the system failure probability; and Improved (${\mu}+{\lambda}$) constrained differential evolution (ICDE) is employed for the optimization process. System reliability assessment of several numerical examples and system RBDO of different truss structures are proposed to verify our results. Moreover, the effect of different classes of interval distribution parameters on the optimum weight of the structure and the reliability index are also investigated. The results indicate that the weight of the structure is increased by increasing the uncertainty level. Moreover, it is shown that for a certain random variable, the optimum weight is more increased by the translation interval parameters than the rotation ones.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.43-46
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• 1997

Reliability engineering is regarded as the major and important roll for all industry. And advanced manufacturing systems with high sped and intelligent have been developing for betterment of machining ability. In this study, we have systemized evaluation of reliability for machinery system. We proposed the reliability assessment and designed and manufactured reliability test-bed to evaluate reliability. In addition we acquired reliability data using test-bed system and made database to handle reliability data. And also we not only use reliability data by analyzing reliability, but also apply design review method using analyzing critical units of machinery system. Form this study, we will expect to guide and increase the reliability engineering in developing and processing phase of high quality product.