타입-2 퍼지집합을 이용한 퍼지 공학시스템의 신뢰도 분석

전병찬,조상엽 한국지식정보기술학회 2022 한국지식정보기술학회 논문지 Vol.17 No.5

공학시스템의 설계에서 시스템의 신뢰도를 보장하는 것은 중요한 주제 중에 하나이다. 공학시스템의 신뢰도는 하위시스템의 순차 또는 병렬 구성요소를 반영하여 각각 방법으로 신뢰도를 계산한 후, 전체 공학시스템의 신뢰도를 평가하게 되면 시스템의 신뢰도를 계산하는 것이 가능하게 된다. 본 연구에서는 타입-2 퍼지집합을 이용하여 공학시스템의 신뢰도를 분석하는 방법을 제안한다. 타입-2 퍼지집합은 퍼지집합을 삼차원적으로 표현하므로 기존의 퍼지집합-퍼지집합, 직관 퍼지집합, 모호집합, 수준 (λ,1) 구간값 퍼지집합, 뉴트로소픽 집합, 팔각형 직관 퍼지집합, 다각형 타입-1 퍼지집합 등-보다 더 다양한 형태의 퍼지집합을 표현하는 것이 가능하다. 또한 소속값을 단위 구간 [0, 1] 사이의 임의의 값을 가질 수 있는 이차 소속값으로 표현하므로 신뢰도를 하나의 실수로 표현하는 타입-1 퍼지집합보다 소속값을 더 유연하게 표현하는 것이 가능하다. 그리고 신뢰도공학에서 제시하는 가능성척도 기반의 두 가지 가정을 수용하므로 신뢰도를 평가하는데 타입-2 퍼지집합을 사용하는 이론적 근거를 가지고 있다. 타입-2 퍼지집합을 이용하여 신뢰도를 계산하는 방법은 퍼지 공학시스템, 퍼지 의사결정시스템, 퍼지 신뢰도공학, 퍼지 추론시스템 등에 적용하는 것이 가능하다. The guarantee for the reliability of systems in the design of engineering systems is one of the important issues. The reliability of the engineering systems can be analyzed by evaluating the reliability of the entire engineering systems after calculating the reliability in each method by reflecting the sequential or parallel components of the subsystems. In this study, we propose the method for analyzing the reliability of the engineering systems using type-2 fuzzy sets. Since type-2 fuzzy sets represent the fuzzy set as the three dimensional, it is possible to represent more various shape of fuzzy sets than the conventional fuzzy sets-fuzzy sets, intuitionistic fuzzy sets, vague sets, level (λ,1) interval-valued fuzzy sets, neutrosophic sets, octagonal intuitionistic fuzzy sets, polygonal type-1 fuzzy sets, etc-. In addition, since the degree of membership is represented as the secondary grade which may take any value from unit interval [0, 1], it becomes possible to express the degree of membership more flexible than the type-1 fuzzy sets that represent the reliability as one real number. And then it accepts the two assumptions based on the possibility measure of fuzzy reliability engineering, it has theoretical bases for using type-2 fuzzy sets to evaluate reliability. The proposed method of obtaining the reliability based type-2 fuzzy sets can be applied to fuzzy engineering systems, fuzzy decision making systems, fuzzy reliability engineering, fuzzy inference systems, etc.

Reliability-Based Design for Market Systems (RBDMS) : Case Study on Electric Vehicle Design

Ungki Lee(이웅기),Namwoo Kang(강남우),Ikjin Lee(이익진) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

When designing a product, both engineering uncertainty and market heterogeneity should be considered to reduce the risk of failure in the market. Reliability-based design optimization (RBDO) approach allows decision makers to achieve target confidence in product performance under engineering uncertainty. On the other hand, design for market systems (DMS) approach helps decision makers to find profit-maximized product design under market heterogeneity. This paper proposes a reliability-based design for market systems (RBDMS) framework for electric vehicle (EV) design by integrating RBDO and DMS approaches. In RBDO, the product quality is controlled based on arbitrarily defined reliability. However, from the viewpoint of the company, it is necessary to set the appropriate reliability since the increased reliability increases both consumer satisfaction and manufacturing cost. Therefore, by modeling how reliability affects the customer choice, the optimum reliability which maximizes the profit can be derived. The “reliability” in the framework is used as follows: (1) a decision variable; (2) an attribute that directly influences the customer preference; (3) standards to determine advertised performance; and (4) reliability constraints in engineering model. We optimized and compared four scenarios depending on whether engineering systems are deterministic or probabilistic, and whether a market is homogeneous or heterogeneous. The results show that designing an entry EV model with low reliability is recommended under engineering uncertainty and market heterogeneity, while designing a premium EV model with high reliability is recommended to ensure the robustness of the profit.

우주발사체 개발사업에서 신뢰성공학의 시스템엔지니어링 인터페이스

신명호,조상연,조미옥,Shin, Myoung Ho,Cho, Sang Yeon,Joh, Miok 한국시스템엔지니어링학회 2006 시스템엔지니어링학술지 Vol.2 No.1

Development of launch vehicle needs a large-scale and complicated System Engineering discipline interfacing to small-quantity production with special manufacturing processes. In general, the System Engineering discipline of launch vehicle has its relationship with Production, Operations, Product Assurance and Management disciplines and its internal partitions into the functions of System Engineering Integration & Control, Requirements Engineering, Analysis, Design and Configuration and Verification. As a function of Product Assurance, reliability of launch vehicle plays an significant role in risk management, system safety, flight safety and launch certification through design assurance. Moreover, major functions of systems engineering are integrated by means of reliability in the phases of design and verification. Therefore, derailed identification of system engineering interfaces of reliability, and execution of tasks for reliability assurance is required for successful development of launch vehicle. This paper identifies specific pattern and mechanism of the interfaces between reliability and system engineering.

국내 무기체계 분야의 소프트웨어 신뢰성 추정 모델 적용 사례

박다운 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.6

국내 무기체계 연구개발과정에서 소프트웨어 신뢰성이 중요한 요소로 여겨지고 있다. 그래서 무기체계 소프트웨어 연구개발 절차에는 소프트웨어 신뢰성 향상을 위한 활동들이 포함되어 있다. 하지만 개발절차에 포함된 활동은 소스코드 정적 및 동적 분석으로 국제 표준에서 요구하는 활동과 다소 차이가 존재한다. 소프트웨어 신뢰성 관련 국제 표준인 IEEE std 1633-2016에서는 소프트웨어 신뢰성 확보를 위한 프로세스를 정의하고 있으며, 이들 가운데 소프트웨어 신뢰성 추정을 필수 활동이라고 이야기하고 있다. 소프트웨어 신뢰성 추정은 시험단계의 결함을 기반으로 통계 모델을 활용해 현재 시점의 소프트웨어 신뢰성을 추정하는 활동이다. 추정한 모델을 기반으로 소프트웨어 고장률을 추정할 수 있으며, 목표 고장률과의 비교를 통해 시험 종료 여부를 결정할 수 있다. 따라서 본 연구에서는 무기체계 소프트웨어 개발 과정에 소프트웨어 신뢰성 추정 모델을 적용하였다. 그 결과 목표한 소프트웨어 신뢰성을 달성하기 위해 지속적인 시험이 진행되었으며, 정량적인 소프트웨어의 신뢰성을 확인 할 수 있었다. 본 연구를 기반으로 무기체계 소프트웨어의 개발 과정에서 국제 표준에서 제시한 소프트웨어 신뢰성 공학 프로세스를 반영하는 노력이 지속적으로 이루어지기를 기대한다. In the domain of Korean weapon system development, issues about software reliability have become crucial factors when developing a weapon system. There is a process required for weapon system software development and management that includes certain activities required to improve the reliability of software. However, these activities are biased toward static and dynamic analyses of source code and do not include activities necessarily required by the international standard. IEEE std. 1633-2016 defines a process for software reliability engineering and describes software reliability estimation as an essential activity in the process. Software reliability estimation means that collecting defective data during the test and estimating software reliability by using the statistical model. Based on the estimated model, developers could estimate the failure rate and make comparisons with the objective failure rate to determine termination of the test. In this study, we collected defective data and applied reliability estimation models to analyze software reliability in the development of a weapon system. To achieve objective software reliability, we continuously tested our software and quantitatively calculated software reliability. Through the research, we hope that efforts to include activities described by the international standard will be carried out in the domain of Korean weapon system development.

퍼지 소프트집합을 이용한 퍼지 공학시스템의 퍼지 신뢰도 평가

조상엽 한국지식정보기술학회 2024 한국지식정보기술학회 논문지 Vol.19 No.3

본 논문에서는 퍼지 소프트집합을 이용하여 공학 시스템의 신뢰도를 평가하는 방법을 제안한다. 공학 시스템 구성요소의 신뢰도가 단일한 값이 아닌 복수 갱이 인자로 표현해야만 하는 경우에 공학 시스템이 구성요소에 대한 신뢰도를 기존의 퍼지집합으로 적용하는 것은 어려울 수가 있다. 이러한 문제를 해결할 수 있는 방안이 퍼지 소프트집합이다. 퍼지 소프트집합은 기존의 소프트집합의 원소의 소속정도를 퍼지집합으로 표현할 수 있게 확장한 퍼지집합의 하나이다. 퍼지 소프트집합을 이용하여 신뢰도를 평가할 때 복수 개의 신뢰도 값이 필요한 구성요소는 퍼지 소프트집합의 전체집합의 원소로 표현하고 복수 개의 신뢰도 값이 필요한 구성요소의 신뢰도는 퍼지 소프트집합의 파라미터 집합의 원소로 표현한다. 퍼지 소프트집합의 파라미터 집합의 원소로 표현되는 구성요소의 복수 개 신뢰도는 퍼지집합 연산을 사용하여 계산하고 이러한 연산의 결과를 기반으로 전체 공학 시스템의 신뢰도를 평가하는 가능하게 된다. 제안한 방법은 복수 개의 신뢰도 표현이 필요한 구성요소를 가지는 공학 시스템과 다기준 의사결정 시스템 등에 적용하는 것이 가능하다. In this paper, we propose a method to evaluate the reliability of the engineering systems using the fuzzy soft sets. When the reliability of components of the engineering systems must be expressed as multiple factors rather than a single value, it may be difficult to applying the conventional fuzzy sets to get the reliability for the components of engineering system. A way to solve this problem is the fuzzy soft sets. The fuzzy soft sets are a kind of the fuzzy sets that has been expanded so that belongingness degree of the elements of a soft set can be expressed as the fuzzy sets. When evaluating reliability using the fuzzy soft sets, the components that require multiple reliability values are expressed as elements of the universal set of the fuzzy soft sets, and the reliability for the components that require multiple reliability values are expressed as elements of the parameter set of the fuzzy soft set. The multiple reliability of components expressed as elements of the parameter set of the fuzzy soft set is calculated using the fuzzy set operations, and it is possible to evaluate the reliability of the entire engineering system based on the results of these operations. The method can be applied to the engineering systems and the multi-criteria decision-making systems that have components that require expressing multiple reliability.

Optimization of backpropagation neural network models for reliability forecasting using the boxing match algorithm: electro-mechanical case

Tanhaeean M,Ghaderi S F,Sheikhalishahi M 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.2

Presenting a robust intelligent model capable of making accurate reliability forecasts has been an attractive topic to most industries. This study mainly aims to develop an approach by utilizing backpropagation neural network (BPNN) to predict the reliability of engineering systems, such as industrial robot systems and turbochargers, with reasonable computing speed and high accuracy. Boxing match algorithm (BMA), as an evolutionary metaheuristic algorithm with a new weight update strategy, is proposed to bring about performance improvements of the ANN in reliability forecast. Consequently, the hybrid model of BMA-BPNN has been provided to gain a significant level of accuracy in optimizing the weight and bias of BPNN using three sets of function approximation data to benchmark the proposed approach’s performance. Then, the BMA is utilized to improve reliability forecasting accuracy in engineering problems. The obtained results reveal that the presented algorithm delivers exceptional performance in function approximation, and its performance in forecasting engineering systems’ reliability is about 20% better than further compared algorithms. Similarly, rapid convergence rate, reasonable computing time, and well-performing are additional characteristics of the presented algorithm. Given the BMA-BPNN characteristics and the acquired findings, we can conclude that the proposed algorithm can be applicable in forecasting engineering problems’ reliability.

픽쳐 퍼지집합을 이용한 퍼지시스템 신뢰도 분석

조상엽 한국지식정보기술학회 2018 한국지식정보기술학회 논문지 Vol.13 No.5

Reliability analysis is the important discipline of reliability engineering. In conventional reliability analysis, the reliability of the components of a system is represented as exact values. Obtaining these data under changing environment conditions is often difficult. Hence fuzzy set theory is used to analyze the fuzzy system reliability, where the reliabilities of the components of a system are represented by fuzzy sets. There are various types of fuzzy sets used to evaluate the reliability of the systems such as the fuzzy sets, interval valued fuzzy sets, intutionistic fuzzy sets, picture fuzzy sets. In the fuzzy sets, the degree of membership is represented as a real number. In the interval valued fuzzy sets, the degree of membership is represented as an interval [, ], where is the minimum degree of membership and is the maximum degree of membership. [, ] ⊆ . In the intuitionistic fuzzy sets, the degree of membership consist of and , where is the degree of membership and is the degree of non-membership. , ∈ . In the picture fuzzy sets, the degree of membership consist of , , and , where is called the degree of positive membership, is called the degree of neutral membership, and is called the degree of negative membership. , , ∈ . In this paper we propose the way to analyze the fuzzy system reliability based on the picture fuzzy sets. The picture fuzzy sets have the capability of representing the positive, negative, neutral, and refusal situation. Therefore the picture fuzzy sets become more flexible to describe the reliabilities than the other methods.

구간값 피타고라스 퍼지집합에 기반을 둔 퍼지 공학시스템 신뢰도 분석

조상엽 한국지식정보기술학회 2023 한국지식정보기술학회 논문지 Vol.18 No.6

The reliability of the engineering systems operating in the real world has an important meaning. Such reliability becomes difficult to obtain an accurate reliability due to inaccurate data, wrong manipulation, etc. To solve this problems, the fuzzy sets have been used. There are several fuzzy sets used to calculate reliability. In the fuzzy sets, it is expressed as a real number , which is the belongingness degree of the fuzzy set. ∈ . In the intuitionistic fuzzy sets, the belongingness degree of the fuzzy set is expressed as , and the non-belongingness degree is described as respectively. , ∈ , 0 ≤ + ≤ 1. In the interval-valued intuitionistic fuzzy sets, the belongingness degree of the fuzzy set is expressed as [, ] and the non-belongingness degree is represented as [, ] respectively. , , , ∈ , + ≤ 1, 0 ≤ + ≤ 1, 0 ≤ + ≤ 1. In the Pythagorean fuzzy sets, the belongingness degree in a fuzzy set is expressed as , and the non-belongingness degree is expressed as . , ∈ , 0 ≤ + ≤ 1. In this paper, we propose a method for calculating the reliability of the fuzzy engineering systems using the interval-valued Pythagorean fuzzy sets that can express flexibility in the Pythagorean fuzzy sets.

다각형 구간 타입-2 퍼지집합을 이용한 퍼지 공학시스템의 신뢰도 분석

조상엽 한국지식정보기술학회 2022 한국지식정보기술학회 논문지 Vol.17 No.5

공학시스템을 운영하는 경우 사용자의 실수, 입력 오류, 입력 데이터의 불확실성 등에 의해 신뢰도가 떨어지는 출력을 생산하게 된다. 이러한 문제를 제어하기 위한 방법은 시스템의 구성요소의 신뢰도를 반영하여 전체 공학시스템이 신뢰도를 출력에 반영하는 것이다. 본 논문에서는 공학시스템의 신뢰도를 평가하기 위하여 퍼지집합 이론을 기반으로 신뢰도를 계산하는 방법을 사용한다. 퍼지집합의 종류에는 소속값을 실수로 표현하는 전통적인 퍼지집합, 과 소속값을 구간으로 표현하는 직관퍼지집합, 구간으로 표현되는 소속값의 상한은 1로 고정하고 하한을 λ로 표현하는 수준 (λ,1) 구간값 퍼지집합, 불확정성을 표현할 수 있는 뉴트로소픽 집합, 다양한 퍼지집합을 표현하기 위한 다각형 타입-1 퍼지집합, 전통적인 퍼지지합의 소속값을 소속함수로 표현하는 타입-2퍼지집합 등이 제안되었다. 본 연구에서 우리는 다각형 구간 타입-2 퍼지집합을 이용하여 공학시스템의 신뢰도를 평가하는 방법을 제안한다. 구간 타입-2 퍼지집합은 이차 소속값이 모두 1과 같은 값을 가진다. 다각형 구간 타입-2 퍼지집합은 하한 소속함수와 상한 소속함수가 다각형으로 표현된다. 그러므로 기존의 퍼지집합들 보다 더 다양한 모양의 퍼지집합을 표현하는 것이 가능하게 된다. In the case of operating the engineering systems, the low reliable output of the systems may produced due to users error, input error, uncertainty of input data, etc. The way to overcome these problem is that the reliability of the entire engineering systems is reflected in the output by reflecting the reliability of the components of the systems. In this paper, in order to analyze the reliability of the engineering systems, we use the fuzzy set theory for calculating the reliability. The fuzzy sets have various types of sets such as the conventional fuzzy sets that represents the degree of membership as a real number, the intuitive fuzzy sets that expresses the degree of membership as an interval, the level (λ,1) interval valued fuzzy set that describe the upper bound of interval is fixed at 1 and the lower bound represent λ, the neutrosophic sets that can express the indeterminacy, the polygonal type-1 fuzzy sets that can describe various shape of conventional fuzzy sets, the type-2 fuzzy sets that represent the membership degree of conventional fuzzy sets as the membership function. In this study, we propose a method to analysis the reliability of engineering systems using polygonal interval type-2 fuzzy sets. In the interval type-2 fuzzy sets, secondary grades are all equal to 1. In the polygon interval type-2 fuzzy sets, the lower membership function and the upper membership function are expressed as polygons. Therefore, it becomes possible to represent fuzzy sets of more various shapes than the conventional fuzzy sets.

An Integrated Reliability Analysis Model of Sheet Pile Wharfs Based on Virtual Support Beam Model and Artificial Intelligence Algorithm

Fengyuan Jiang,Sheng Dong 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.7

Sheet pile wharfs are widely used coastal structures with good adaptability for geological conditions. A reliability evaluation is required for safety. Challenges are raised from the complicated solution in both the structural response and reliability. To provide a flexible and efficient approach, an integrated reliability analysis model was proposed: The virtual simply support beam (VSSB) model was developed to estimate the structural response; Based on probabilistic methodologies and artificial intelligence (AI) models, the limit state surface was fitted to search reliability solutions. A case study was used to illustrate the applicability of the proposed model and compare the prediction performance of AI models. An extensive parametric study was performed to investigate the influential factors on structural reliability. Compared with finite element analysis, the VSSB model presented reasonable estimations on structural response. The genetic programming performed best in predicting structural response with an average relative absolute error (RAE) of 0.018. The corresponding integrated models gave the reliability solutions with an average RAE of less than 0.014. Soil parameters in different positions significantly affected the structural stability, that the material qualities should be addressed. This study provides references in engineering safety design and guidelines the reliability analysis framework for complicated structures.