• Journal of the Korean Institute of Intelligent Systems
• /
• v.3 no.1
• /
• pp.65-75
• /
• 1993

Fuzzy data is a phenomenon often occurring in real life. There is the inherent vagueness of classification terms referring to a continuous scale, the uncertainty of linguistic terms such as "I almost agree" or the vagueness of terms and concepts due to the statistical variability in communication [20] and many more. Previously, such fuzzy data was approximated by non-fuzzy (crisp) data, which obviously did not lead to a correct and precise representation of the real world. Fuzzy set theory has been developed to represent and manipulate fuzzy data [18]. Explicitly managing the degree of fuzziness in databases allows the system to distinguish between what is known, what is not known and what is partially known. Systems in the literature whose specific objective is to handle imprecision in databases present various approaches. This paper is concerned with the different ways uncertainty and imprecision are handled in database design. It outlines the major areas of fuzzification in (relational) database systems.

• Structural Engineering and Mechanics
• /
• v.6 no.1
• /
• pp.17-30
• /
• 1998

The method of pairwise comparison inherently contains information of ambiguity, fuzziness and conflict in design goals for a multiobjective structural design. This paper applies the principle of paired comparison so that the vaguely formulated problem can be modified and a set of numerically acceptable weight would reflect the relatively important degree of multiple objectives. This paper also presents a fuzzy global criterion method ($FGCM_{\lambda}$) included fuzzy constraints that coupled with the objective weighting rank obtained from the modified pairwise comparisons for fuzzy multiobjective optimization problems. Descriptions in sequence of this combined method and problem solving experiences are given in the current article. Multiobjective design examples of truss and mechanical spring structures illustrate this optimization process containing the revising judgement techniques.

• IEIE Transactions on Smart Processing and Computing
• /
• v.4 no.4
• /
• pp.209-215
• /
• 2015

Fuzzy c-means method is typical soft clustering, and requires a degree of membership that indicates the degree of belonging to each cluster at the time of clustering. Parameter values greater than 1 and less than 2 have been used by convention. According to the proposed data-generation scheme and the simulation results, some behaviors in the degree of "fuzziness" was derived.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.20 no.43
• /
• pp.37-46
• /
• 1997

제품의 정성적 품질평가에서, 제품의 최종품질을 구성하는 다수의 특성에 대한 만족도가 언어로써 표현되어 소비자의 구매행동이란 의사결정으로 표출되는데, 이러한 주관적 평가에는 평가의 애매함(fuzziness)이 수반되므로 품질의 평가구조를 합리적으로 파악하기 위해서는 애매함의 존재를 고려에 넣지 않으면 안된다. 다수의 품질특성이 계층적(hierarchical)인 구조로 연결되어 최상위 품질특성으로 구성되며, 특성간의 중요도(relative importances)가 계층별로 결정되는 경우, 이들 개개의 특성에 대한 만족도의 평가로부터 어떤 구조적인 관계를 통해 그 제품에 대한 종합평가가 이루어지나, 개개의 특성에 대한 평가가 애매한 이상 최종 결과인 종합적 만족도도 애매한 것으로 된다. 즉, 평가모델의 구조도 평가의 패턴도 퍼지화되므로 이러한 평가에서 퍼지이론의 응용에 따른 효과를 가장 크게 기대할 수 있는 퍼지추론모델을 이용하여 계층간, 품질특성간의 퍼지관계와 특성의 중요도 및 언어변수(linguistic variables)의 형태로 주어지는 입력정보로써 품질구조를 명확히 하고, 패턴인식(pattern recognition)의 개념을 이용하여 평가자의 제품에 대한 평가결과를 언어로써 표현한다.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.34 no.2
• /
• pp.9-18
• /
• 2011

Vender prioritization process is one of the most critical tasks of production and logistics management for many companies. Determining the most critical criteria for vender prioritization process is a vital means for a purchasing company to improve its supply chain productivity. This study discuss the use of a Fuzzy analytic network process (Fuzzy ANP) model which is an efficient tool to handle the fuzziness of the data involved in deciding the preferences of different criteria which are not independent. Also, the comparison of classical ANP and Fuzzy ANP is described using simulation with triangular distribution random number generation. It is shown that Fuzzy ANP model possesses some attractive properties and could be used as an alternative to the known vender prioritization methods.

• Proceedings of the KIEE Conference
• /
• 1999.07g
• /
• pp.2876-2878
• /
• 1999

There have been several tipical methods being used to measure the fuzziness (entropy) of fuzzy sets. Pedrycz is the original motivation of this paper. This paper studies the entropy variation on the fuzzy numbers with arithmetic operations(addition, subtraction, multiplication). It is shown that through the arithmetic operations, the entropy of the resultant fuzzy number has the arithmetic relation with the entropy of each original fuzzy number. This paper generalize earlier results of Pedrycz [FSS 64(1994) 21-30] and Wang and Chiu [FSS 103(1999) 443-455].

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.159-162
• /
• 1993

A new approach using fuzzy dynamic programming is proposed for the flexible long-term generation mix under uncertain circumstances. A characteristic feature of the presented approach is that not only fuzziness in fuel and construction cost. load growth and reliability but also many constraints of generation mix can easily be taken into account by using fuzzy dynamic programming. The method can accommodate arbitrary shape of membership function as well as the operation of pump-generator. And so more realistic solution can be obtained. The effectiveness of the proposed approach is demonstrated by the best generation mix problem of KEPCO-system which contains nuclear, coal, LNG, oil and pump-generator hydro plant in multi-years.

• Journal of Navigation and Port Research
• /
• v.35 no.2
• /
• pp.173-178
• /
• 2011

This study determined the ship replacement life expectancy from an economic perspective. There are many ambiguities in the cost for calculation of economic lifespan, and these were expressed as fuzzy numbers. Also, a fuzzy cost model using fuzzy numbers was developed and suggested as a more practical analysis method than the existing cost model. And the suggested fuzzy model was used to determine the economic lifespan for various types of container ships. As the result, Without fuzziness, the economic lifespan of 5000 TEU Ships was found to be 19 years. it was found that the greater the container ship, the greater the economic lifespan was.

• Journal of the military operations research society of Korea
• /
• v.18 no.1
• /
• pp.47-60
• /
• 1992

A class of allocation problems can be modeled in a linear programming formulation. But in reality, the coefficient of both the cost and constraint equations can not be generally determined by crisp numbers due to the imprecision or fuzziness in the related parameters. To account for this. a fuzzy version is considered and solved by transforming to a conventional non-linear programming model. This gives a solution as well as the degree that the solution satisfies the objective and constraints simultaneously and hence will be very useful to a decision maker. An attacker assignment problem for multiple fired targets has been modeled by a linear programming formulation by Lemus and David. in which the objective is to minimize the cost that might occur on attacker's losses during the mission. A fuzzy version of the model is formulated and solved by transforming it to a conventional nonlinear programming formulation following the Tanaka's approach. It is also expected that the fuzzy approach will have wide applicability in general allocation problems

• Journal of Mechanical Science and Technology
• /
• v.20 no.6
• /
• pp.731-737
• /
• 2006

Interactive Fuzzy Physical Programming (IFPP) developed in this paper is a new efficient multi-objective optimization method, which retains the advantages of physical programming while considering the fuzziness of the designer's preferences. The fuzzy preference function is introduced based on the model of linear physical programming, which is used to guide the search for improved solutions by interactive decision analysis. The example of multi-objective optimization design of the spindle of internal grinder demonstrates that the improved preference conforms to the subjective desires of the designer.