• Journal of the KSME
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• v.55 no.10
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• pp.36-39
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• 2015

이 글에서는 초고온가스로 노심 흑연 구조물의 신뢰성 평가 관련 이해를 돕기 위해 원자력급 흑연의 일반적인 특성, 흑연 구조물의 파손 평가 모델 및 이론, ASME 응력 평가 모델에 대해 기술하고자 한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.605-613
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• 2014

Epistemic uncertainty, the lack of knowledge, is often more important than aleatory uncertainty, variability, in estimating reliability of a system. While the probability theory is widely used for modeling aleatory uncertainty, there is no dominant approach to model epistemic uncertainty. Different approaches have been developed to handle epistemic uncertainties using various theories, such as probability theory, fuzzy sets, evidence theory and possibility theory. However, since these methods are developed from different statistics theories, it is difficult to interpret the result from one method to the other. The goal of this paper is to compare different methods in handling epistemic uncertainty in the view point of calculating the probability of failure. In particular, four different methods are compared; the probability method, the combined distribution method, interval analysis method, and the evidence theory. Characteristics of individual methods are compared in the view point of reliability analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.4
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• pp.61-68
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• 1986

This paper presents a method for developing a probability-based working stress design code for reinforced concrete. Reliability of reinforced concrete structural members is evaluated by using an advanced second moment reliability method, and then, a practical method for code calibration is shown in this paper. The target reliability indices for various structural elements are determined by considering the results of the numerical studies on the safety of the structures designed by the current code, and by reflecting the construction practice. A set of allowable stresses and safety factors for reinforced concrete is proposed as a possible substitute for the current safety provisions, based on the rational target reliability indices.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.166-169
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• 2011

현재 국내에서 사용하고 있는 교량구조물의 성능평가방법으로는 크게 공용하중에 대한 내하율을 구하기 위하여 허용응력개념이나 강도설계 개념을 적용한 내하력 평가 기법이 사용되고 있다. 그러나 위의 방법들은 일반적으로 공용연수의 경과에 따른 재료 및 구조적 성능의 손실과 여러 가지 하중 및 환경적 요인들의 불확실성으로 인하여 발생하는 손상 및 열화를 반영하기 어렵다. 그리고 제원 및 재료물성치의 불확실성에 대한 기존 설계 자료의 DB 부족으로 기존의 평가방법에서는 이러한 시간의 경과에 따른 성능저하를 정확히 산정할 수 없어 이론상의 값과 실제 구조물과의 차이로 인한 불확실성이 존재 한다. 이에 본 연구에서는 공용년수 경과에 따른 시설물의 재료 구조적인 성능 및 거동분석 수행, 신뢰성 해석 수행을 바탕으로 교량 안전성 평가의 합리성 및 현실성을 제고하며, 구조 신뢰성 해석을 수행함으로써 실제 구조물의 강도 한계상태에 대한 파괴확률을 산정하고 그에 대응하는 위험도를 평가함으로써 안전성 검토를 수행하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.888-891
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• 2003

개방형 네트워크를 통한 전자거래는 무엇보다도 거래의 신뢰성 제고 측면에서 집중적으로 논의되고 있는데 이를 확보하기 위한 중요한 수단으로서 전자서명과 인증제도 방안이 가장 주목을 받고 있다. 전자서명은 기술적으로 암호기술을 이용하여 통신내용의 무결성과 기밀성을 보장받고, 법적으로는 근거법의 제정을 통하여 전자문서와 전자서명의 효력을 부여받아 그 신뢰성을 확보하게 되는 것이다. 특히 P2P기반의 개방형 시스템 환경에서 신뢰성, 무결성, 부인금지와 같은 각종 기술적 선결과 제들을 해결하고 거래의 신뢰성을 제고하기 위한 여러 가지 전자서명 방안들 중에서도 현재까지 공개키 암호화방식과 일방적 해쉬함수의 추출물 알고리즘을 결합한 디지털서명이 가장 믿을 만한 전자서명 방안으로 인정받고 있는 실정이다. 본 연구는 P2P 전자서명 모델에 개인 간 전자서명모델 이론을 조명하고 P2P 전자문서를 안전하고 신뢰성 있게 이용 할 수 있는 여건을 조성 할 수 있도록 공개키 암호기술에 기반을 두었으며 P2P상에서 전자서명 프로그램이 원활히 작동하도록 설계하고 전자 서명된 문서가 변질되지 않고 상호간의 사용자에게 신뢰할 수 있도록 하였다.

• Asia Marketing Journal
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• v.1 no.1
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• pp.6.1-6.16
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• 1998

입찰계약방식은 발주기업인 구매자가 최선의 공급자를 결정하기 위해 선택 가능한 하나의 전략적 도구로서 매우 중요한 의의를 지니고 있다. 본연구는 대리이론과 거래비용분석에 의해 발주기업의 입찰계약방식결정에 영향을 미치는 요인을 이론적으로 제시하고 있다. 본 연구는 입찰계약방식이 거래의 관계지향성과 계약의 명시성의 두가지 차원을 본질로 하고 있으며, 이들 두가지 차원에 영향을 미치는 요인으로 정보의 비대칭성, 지각된 위험의 크기, 성과측정 및 감시의 필요성, 응찰기업에 대한 신뢰와 몰입수준, 발주기업의 상대적 의존도의 다섯 가지 요인을 들고 있다. 본연구는 입찰계약방식이 이들 요인에 의해 어떻게 결정되는가를 명제의 형태로 제시하고 있으며, 실증분석을 위한 몇 가지 제언도 함께 제시하고 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.21-32
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• 1981

Recent trends in design standards development in some European countries and U.S.A. have encouraged the use of probabilistic limit sate design concepts. Reliability based design criteria such as LSD, LRFD, PBLSD, adopted in those advanced countries have the potentials that they afford for symplifying the design process and placing it on a consistent reliability bases for various construction materials. A reliability based design criteria for RC flexural members are proposed in this study. Lind-Hasofer's invariant second-moment reliability theory is used in the derivation of an algorithmic reliability analysis method as well as an iterative determination of load and resistance factors. In addition, Cornell's Mean First-Order Second Moment Method is employed as a practical tool for the approximate reliability analysis and the derivation of design criteria. Uncertainty measures for flexural resistance and load effects are based on the Ellingwood's approach for the evaluation of uncertainties of loads and resistances. The implied relative safety levels of RC flexural members designed by the strength design provisions of the current standard code were evaluated using the second moment reliability analysis method proposed in this study. And then, resistance and load factors corresponding to the target reliability index(${\beta}=4$) which is considered to be appropriate level of reliability considering our practices are calculated by using the proposed methods. These reliability based factors were compared to those specified by our current ultimate strength design provisions. It was found that the reliability levels of flexural members designed by current code are not appropriate, and the code specified resistance and load factors were considerably different from the reliability based resistance and load factors proposed in this study.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.6
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• pp.575-582
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• 2008

Carbonation is one of major factors influencing on the durability of concrete structure. This paper investigates the effect of carbonation on the soundness of harbor concrete structure and quantifies the influence of carbonation based on in-situation data tested at 369 points in 69 harbor facilities. The relationships between carbonation depth and cover depth, and between carbonation depth and compressive strength are studied and the failure probability of durability, that is the initiation probability of steel corrosion, is evaluated on the basis of reliability concept. The in-situation test results showed that the ratio of carbonation depth to cover depth was less than 0.2, and the carbonation depth increased with age. In most cases, the failure probability of durability by carbonation was less than 10%. Therefore, it can be concluded that the influence of carbonation on the durability of harbor concrete structure is smaller than other factors deteriorating the durability of harbor concrete structure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.21-29
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• 1993

In this paper, a probability-based reliability analysis was proposed based on a finite element method-based random vibration analysis and serviceability limit state of structures. The limit state model defined for the study is a serviceability limit state in terms of the more realistic crack failure that might cause the emission of radioactive materials. The SAP V-2 is used for a three-dimensional finite element analysis of concrete containment structure, and the reliability analysis is carried out by modifying HRAS reliability analysis program for this study. In this study, the load factors for the design of reinforced concrete cointainment structures in Korea are proposed by considering appropriate load combination criteria for design, and the results are compared with the present ASME code. The proposed load factors were proved to be in accordance with a set of code performance objective and showed consistency in the limit state probability.

• International Journal of Highway Engineering
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• v.5 no.1 s.15
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• pp.1-10
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• 2003

The objective of pavement design, just as with the design of other structures, is to obtain the most economical designs at specified levels of reliability. Methods that yield designs with different levels of reliability are undesirable, and over the course of time design approaches in the U.S. and Europe have converged toward the Load and Resistance Factor Design (LRFD) format in order to assure uniform reliability. At present the LRFD format has been implemented in concrete, steel, wood and bridge design specifications. In this paper, reliability theories are used to illustrate the development of an LRFD format for Mechanistic-Empirical (M-E) design of flexible pavements as an alternative of its reliability module. It is shown in this paper that ten candidate pavement sections designed with a reliability level using the AASHTO design guide (1986) do not have uniform structural reliability in terms of pavement mechanistic distress such as fatigue cracking and the uniform reliability can be achieved by using the LRFD format.