• International Journal of Reliability and Applications
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• 제2권2호
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• pp.137-146
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• 2001

In general, analysis of the decision problems in nuclear system management involves a simultaneous consideration of various criteria and decision alternatives. Sometimes, it is a complex, unstructured, ill-defined process incorporating the multi-criteria and the data of impreciseness. To cope with this analysis, a fuzzy hierarchical analysis methodology is proposed and demonstrated with a simple example.

• 산업경영시스템학회지
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• 제39권2호
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• pp.138-149
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• 2016

Quality function deployment (QFD) is a widely adopted customer-oriented product development methodology by translating customer requirements (CRs) into technical attributes (TAs), and subsequently into parts characteristics, process plans, and manufacturing operations. A main activity in QFD planning process is the determination of the target levels of TAs of a product so as to achieve a high level of customer satisfaction using the data or information included in the houses of quality (HoQ). Gathering the information or data for a HoQ may involve various inputs in the form of linguistic data which are inherently vague, or human perception, judgement and evaluation for the information and data. This research focuses on how to deal with this kind of impreciseness in QFD optimization. In this paper, it is assumed as more realistic situation that the values of TAs are taken as discrete, which means each TA has a few alternatives, as well as the customer satisfaction level acquired by each alternative of TAs and related cost are determined based on subjective or imprecise information and/or data. To handle these imprecise information and/or data, an approach using some basic definitions of fuzzy sets and the signed distance method for ranking fuzzy numbers is proposed. An example of a washing machine under two-segment market is provided for illustrating the proposed approach, and in this example, the difference between the optimal solution from the fuzzy model and that from the crisp model is compared as well as the advantage of using the fuzzy model is drawn.

• Journal of applied mathematics & informatics
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• 제15권1_2호
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• pp.265-275
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• 2004

In this paper, multi-objective models for designing 3D trajectory of horizontal wells are developed in a fuzzy environment. Here, the objectives of minimizing the length of the trajectory and the error of entry target point are fuzzy in nature. Some parameters, such as initial value, end value, lower bound and upper bound of the curvature radius, tool-face angle and the arc length of each curve section, are also assumed to be vague and imprecise. The impreciseness in the above objectives have been expressed by fuzzy linear membership functions and that in the above parameters by triangular fuzzy numbers. Models have been solved by the fuzzy non-linear programming method based on Zimmermann [1] and Lee and Li [2]. Models are applied to practical design of the horizontal wells. Numerical results illustrate the accuracy and efficiency of the fuzzy models.

• 한국안전학회지
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• 제30권4호
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• pp.151-158
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• 2015

Usually risk assessment is performed for the safety of diverse industries though, many kinds of risks cannot be analyzed effectively by using classical probability models due to lack of experience data and impreciseness of human decision making. For these reasons, fuzzy risk assessment utilizing subjective judgment and experience of skillful experts has been considered as a solution. In this study, to comprehend the relationship between conventional fuzzy theory and human conceptual images on risks, linguistic variables were reviewed with reference to fuzzy membership functions, especially in the Korean language. As interviewees, about a hundred people including students as well as safety engineers voluntarily participated. The research results showed that most people were in favor of adjective expressions decorated with adverbs rather than naive expressions such as "high" or "low", and that directly translated linguistic variables were not appropriate for the Korean people in risk assessment as far. Therefore, with consideration of the selection tendency by the Korean people in linguistic variables, it could be concluded that 5 level expressions would be most favorable for linguistic variables in risk assessments in Korea.

• 한국컴퓨터정보학회논문지
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• 제8권1호
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• pp.156-165
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• 2003

본 연구에서는 기업 내 정보시스템을 구축하는 과정에 있어 의사결정자들을 지원하기 위한 가능성분포 의사결정모형을 검토하였다. 급변하는 기업환경에 영향을 미치는 주요 변수중의 하나인 정보기술의 활용은 성공적인 기업활동에 중요한 역할을 하며, 아웃소싱할 경우 조직의 목표와 자원의 제약을 충분히 반영하는 벤더의 선정이 매우 중요하다 할 수 있다. 이를 위해 수리적 모형이 제시되어졌으며 가능성 이론을 적용한 모형이 제시되었다. 일반적 수리모형의 경우 투입되는 변수의 불명확성과 의사결정자의 열망수준을 반영하지 못한다는 단점이 있으며, 확률적 분포 모형의 경우 현실적 적용에 있어 어려움이 있어왔다. 가능성분포 의사결정모형에서는 투입변수의 불명확성이 고려된 다목적의사결정모형의 구축이 가능하였다.

• 대한지구과학교육학회지
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• 제10권3호
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• pp.254-261
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• 2017

이 연구는 계절 변화에 대한 초등학생들과 벨리즈 초등교사의 선개념을 조사하고 계절 변화의 원인을 이해하는데 도움이 되는 실험을 고안한 것이다. 계절 변화에 대한 선개념을 알아보기 위해 계절변화를 학습하지 않은 초등학교 6학년 91명의 학생과 벨리즈 초등교사 10명을 대상으로 개방형 질문지와 인터뷰를 실시하였으며, 귀납적 분석법을 이용하여 범주화하였다. 초등학생과 벨리즈 초등교사는 계절 변화의 원인을 지구의 자전, 태양과 지구 사이의 거리, 지구의 공전, 환경오염이나 기후변화 등으로 생각하고 있었다. 그리고 이러한 오개념은 공간 인식에 대한 어려움, 교과서나 교재의 부정확함 등에 기인하는 것으로 나타났다. 계절 변화에 대한 부정확한 선개념을 바로 잡고 계절 변화 수업을 개선하기 위하여 지구 자전축의 기울기에 따른 태양의 남중 고도와 낮과 밤의 길이를 측정하고, 이를 비교하는 실험을 고안하였다. 이 실험은 태양의 남중 고도와 낮의 길이 변화와 같은 자연 현상을 모형을 통해 측정할 수 있도록 하여 계절변화의 원인을 이해하는데 도움을 줄 수 있다.

• Journal of Communications and Networks
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• 제8권1호
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• pp.70-84
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• 2006

We propose a new distributed QoS routing scheme called pre-computation based selective probing (PCSP). The PCSP scheme is designed to provide an exact solution to the constrained optimization problem with moderate overhead, considering the practical environment where the state information available for the routing decision is not exact. It does not limit the number of probe messages, instead, employs a qualitative (or conditional) selective probing approach. It considers both the cost and QoS metrics of the least-cost and the best-QoS paths to calculate the end-to-end cost of the found feasible paths and find QoS-satisfying least-cost paths. It defines strict probing condition that excludes not only the non-feasible paths but also the non-optimal paths. It additionally pre-computes the QoS variation taking into account the impreciseness of the state information and applies two modified QoS-satisfying conditions to the selection rules. This strict probing condition and carefully designed probing approaches enable to strictly limit the set of neighbor nodes involved in the probing process, thereby reducing the message overhead without sacrificing the optimal properties. However, the PCSP scheme may suffer from high message overhead due to its conservative search process in the worst case. In order to bound such message overhead, we extend the PCSP algorithm by applying additional quantitative heuristics. Computer simulations reveal that the PCSP scheme reduces message overhead and possesses ideal success ratio with guaranteed optimal search. In addition, the quantitative extensions of the PCSP scheme turn out to bound the worst-case message overhead with slight performance degradation.