• Journal of applied mathematics & informatics
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• 제27권5_6호
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• pp.1459-1463
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• 2009

Recently, Zhao et.al [European Journal of Operational Research 169 (2006) 189-201] discussed a random fuzzy renewal process based on random fuzzy theory. They considered the rate of the random fuzzy renewal process and presented a random fuzzy elementary renewal theorem. They also established Blackwell's theorem in random fuzzy sense. But all these results are invalid. We give a counter example in this note.

• 호남수학학술지
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• 제27권4호
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• pp.543-550
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• 2005

Some properties of a transitive fuzzy matrix are examined and the canonical form of the transitive fuzzy matrix is given using the properties. As a special case an open problem concerning idempotent matrices is solved. Thus we have the same result in a intuitionistic fuzzy matrix theory. In our results a nilpotent intuitionistic matrix and a symmetric intuitionistic matrix play an important role. We decompose a transitive intuitionistic fuzzy matrix into sum of a nilpotent intuitionistic matrix and a symmetric intuitionistic matrix. Then we obtain a canonical form of the transitive intuitionistic fuzzy matrix.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1820-1840
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• 2017

Aiming at the phenomenon of false information issued by service providers in cloud computing environment, a method for service evaluation based on fuzzy theory is put forward in this paper. According to the quality of services provided by cloud service providers and their behavior during interactions, a trust relationship between cloud service providers and cloud service consumers is established, which can be quantified by using fuzzy theory. The quality of services is evaluated by drawing on the trust relationship. In our method, the recommendation credibility of a cloud service consumer is determined through behavior similarity with evaluators and a praise factor. The introduction of the praise factor better suits the phenomenon of a high-quality service getting more repeat customers. The negative impact of dishonest customers is reduced, and the accuracy of trust and cloud service quality evaluation is improved by introducing a confidence factor that can be dynamically adjusted. The experimental results show that our method can effectively and accurately evaluate the trust value and service quality of providers, while weakening the influence of dishonest consumers, and quickly detect dishonest service providers. This is beneficial for consumers trying to find high quality service providers for similar services.

• 한국공간구조학회논문집
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• 제17권2호
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• pp.53-62
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• 2017

This study aims to establish a seismic resistance performance evaluation method that makes sure to secure the seismic resistance performance of the existing mid-low story reinforced concrete structures. This study focuses on the development of the seismic resistance performance evaluation method for the overall seismic resistance performance evaluation on the buildings by applying fuzzy theory. This seismic resistance performance evaluation method considers the mutual relations among the type of force, the type of member, the type of story, and the states of deterioration of the buildings. The total seismic resistance performance index from this method was calculated by the intensity weight of each evaluation item, fuzzy measure, fuzzy integration. Moreover, the evaluation methodology was established in this study to identify the performance level of the Immediate Occupancy, Life Safe, Collapse Prevention by applying the fuzzy theory.

• 호남수학학술지
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• 제26권3호
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• pp.309-330
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• 2004

In this paper, we apply the concept of intuitionistic fuzzy sets to theory of semigroups. We give some properties of intuitionistic fuzzy ideals and intuitionistic fuzzy bi-ideals, and characterize which is left [right] simple, left [right] duo and a semilattice of left [right] simple semigroups or another type of semigroups in terms of intuitionistic fuzzy ideals and intuitionistic fuzzy bi-ideals.

• 한국전자파학회논문지
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• 제21권7호
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• pp.715-725
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• 2010

OFDM(Orthogonal Frequency Division Multiplexing) 시스템은 주파수 선택적 페이딩 채널에서 무선 고속 데이터 전송에 적합한 통신 방식이다. 본 논문에서는 기계 제어에 많이 사용되는 Fuzzy 이론을 이용하여 OFDM 시스템에서 문제가 되는 PAPR(Peak to Average Power Ratio)을 감소시키는 방법을 제안한다. PAPR을 줄이는데 Fuzzy 이론을 사용함으로써 경험적 실험과 반복에 의한 데이터를 사용하기 쉬우며, 하드웨어적인 측면에서 구현이 쉽고, 또한 보다 적은 연산량으로 쉽게 PAPR을 감소시킬 수 있다. 먼저 입력 신호를 부블록으로 나누고, Fuzzy를 이용하여 부블록의 PAPR을 낮추어 전체의 PAPR을 낮추어 전송하여 이를 수신단에서 복원하는 비교적 쉽고 간단한 알고리즘을 제안한다. 제안한 방식이 기존의 OFDM 시스템에 비하여 시스템의 연산량이 다소 증가하고 Fuzzy에 관한 정보를 따로 보내야 하는 단점이 있지만, PAPR 감소 측면에서 성능이 개선됨을 확인하였다. 제안하는 알고리즘의 성능을 평가하기 위해 CCDF(Complementary Cumulative Distribution Function)을 통하여 비교한다. 이 알고리즘에 따르면 QPSK와 16QAM 변조를 사용하여 시뮬레이션을 한 결과, Fuzzy 이론을 이용한 방법이 FFT 크기(N)=512, Oversampling=4인 경우 PR이 $10^{-5}$을 기준으로 각각 최대 약 2.3 dB와 3.1 dB의 PAPR 감소됨을 확인할 수 있었다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2001년도 춘계학술대회 학술발표 논문집
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• pp.136-139
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• 2001

This paper develops a sensor based navigation method that utilizes fuzzy logic and the Dempster-Shafer evidence theory for mobile robot in uncertain environment. The proposed navigator consists of two behaviors: obstacle avoidance and goal seeking. To navigate reliably in the environment, we make a map building process before the robot finds a goal position and create a robust fuzzy controller. In this paper, the map is constructed on a two-dimensional occupancy grid. The sensor readings are fused into the map using D-S inference rule. Whenever the robot moves, it catches new information about the environment and replaces the old map with new one. With that process the robot can go wandering and finding the goal position. The usefulness of the proposed method is verified by a series of simulations. This paper deals with the fuzzy modeling for the complex and uncertain nonlinear systems, in which conventional and mathematical models may fail to give satisfactory results. Finally, we provide numerical examples to evaluate the feasibility and generality of the proposed method in this paper.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1998년도 추계 학술발표회 논문집
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• pp.64-68
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• 1998

This paper discusses the potential application of fuzzy set theory to the decision-making in the area of radioactive waste management. the approach proposed in this study is based on the concepts of fuzzy set theory and the hierarchical structure analysis. The linguistic variables and fuzzy numbers are used to aggregate the decision maker's subjective assessments of the decision criteria and of the decision alternatives with respect to these criteria. For each alternative, the fuzzy appropriateness index is evaluated to obtain the final score. Using total integral value method, one of methods for ranking fuzzy numbers, the fuzzy appropriateness indices are ranked. As a case problem, selection of the most suitable option for spent fuel storage is illustrated.

• 대한기계학회논문집
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• 제18권1호
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• pp.113-120
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• 1994

The dynamic characteristics of turning processes are complex, non-linear and time-varying. Consequently, the conventional techniques based on crisp mathematical model may not guarantee cutting force regulation. This paper presents a fuzzy controller which can regulate cutting force in turning process under varying cutting conditions. The fuzzy control rules are extablished from operator experience and expert knowledge about the process dynamics. Regulation which increases productivity and tool life is achieved by adjusting feedrate according to the variation of cutting conditions. The performance of the proposed controller is evaluated by cutting experiments in the converted conventional lathe. The results of experiments show that the proposed fuzzy controller has a good cutting force regulation capability in spite of the variation of cutting conditions.

• 자원ㆍ환경경제연구
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• 제15권5호
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• pp.921-937
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• 2006

본 연구는 이산선택 조건부가치측정법에 내재되어 있는 응답자의 선호의 불확실성 문제를 퍼지이론을 통해 해결하려 한 것으로, 멸종위기에 처해 있는 한국산 토종반달곰의 보존에 대한 지불의사액을 추정하는 분석과정에 퍼지소속도 함수를 적용하였다. 퍼지소속도 이론은 애매모호한 상황의 불명확성을 추정하는 방법론으로, 이를 조건부가치측정법에 적용하면 해당 환경재에 대한 지불의사액과 응답자들의 진술에 대한 확신도를 동시에 도출해낼 수 있다. 본 연구를 위해 우리나라 7대 광역시에 거주하는 성인남녀 500명을 대상으로 설문조사를 시행하였으며 양분선택형 조건부가치측정법이 사용되었다. 한국산 토종반달곰 보존에 대한 지불의사액은 가구당 월 9,090원으로 계산되었으며 퍼지소속도함수로 계산된 응답의 확신도는 78%인 것으로 추정되었다.