• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1464-1478
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• 2021

Selective Production of Exotic Species is an innovative plant for advanced nuclear physic studies. A radioactive beam, generated by using an UCx target-ion source system, is ionized, selected and accelerated for experimental objects. Very high vacuum conditions and appropriate safety systems to storage exhaust gases are required to avoid radiological risk for operators and people. In this paper, Failure Mode, Effects, and Criticality Analysis of a preliminary design of high activity gas recovery system is performed by using a modified Fuzzy Risk Priority Number to rank the most critical components in terms of failures and human errors. Comparisons between fuzzy approach and classic application allow to show that Fuzzy Risk Priority Number is able to enhance the focus of risk assessments and to improve the safety of complex and innovative systems such as those under consideration.

• 인지과학
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• 제10권4호
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• pp.51-62
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• 1999

본 논문에서는 규칙기반 전문가시스템의 퍼지 생성규칙을 표현할 수 있는 퍼지페트리네트 표현을 제안한다. 퍼지페트리네트 표현을 기반으로, 전진추론 알고리즘과 후진추론 알고리즘으로 구성된 퍼지 추론 알고리즘을 제안한다. 본 논문이 제안한 알고리즘은 단순히 min과 max 계산만을 하는 기존의 알고리즘과는 달리 퍼지 생성규칙의 전제 부와 결론 부에 퍼지 개념의 유무에 따라 적절한 믿음 값 평가 함수을 사용하여 보다 더 인간적인 추론을 한다. 전진추론 알고리즘은 유한한 방향성 나무인 도달나무로 표현할 수 있다. 후진추론 알고리즘은 목표노드에서 시작노드까지의 후진추론 통로를 구한 후에 믿음 값 평가함수를 이용하여 목표노드의 믿음 값을 구한다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.354-362
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• 2000

In Korea, researches on year-round leaf vegetables production system are in progress, most of them focused on environmental control. Therefore, automation technologies for harvesting, transporting, and grading are in great demand. A robot system for harvesting lettuces, composed of a 3-DOF (degree of freedom) manipulator, an end-effector, a lettuce feeding conveyor, an air blower, a machine vision system, six photoelectric sensors, and a fuzzy logic controller, was developed. A fuzzy logic control was applied to determine appropriate grip force on lettuce. Leaf area index and height were used as input variables and voltage as an output variable for the fuzzy logic controller. Success rate of the lettuce harvesting was 94.12%, and average harvesting time was approximately 5 seconds per lettuce.

• 한국정보전자통신기술학회논문지
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• 제11권2호
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• pp.156-160
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• 2018

In the paper, a kind of self-tuning PID control system is designed to keep the honing coolant temperature constant in the process of automobile engine production. The conventional PID control method and the Fuzzy PID control method both are used to design and make the simulation experiment in Matlab. According to the simulation result, the performance of Fuzzy PID control method is obviously better. The Fuzzy PID control system can react faster to get the target temperature and resume normal when external conditions exchanged.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.1155-1158
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• 1993

Proficiency in creating a knowledge base is required for high accuracy fuzzy control. To overcome this a fuzzy inference method is proposed that take these membership functions from the probability densities showing the distribution of the mesurement values. And a method using a rough fuzzy knowledge base automatically created from the basic measurement data and tuned using the gradient method is proposed. In actual tests, these were applied to automatic high accuracy adjustment devices for magnetic head and for high frequency circuits with good results.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.751-758
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• 2021

군수품은 품질 보증을 위해 개발과 양산단계에서 위험 식별을 수행해야 한다. 위험 식별은 부품, 구성품, 계통 등에 대한 고장 요소를 분석하는 것으로, 다양한 신뢰성 기법 중에서 고장 모드 영향 분석(FMEA)을 이용하고 있다. FMEA는 위험 식별 중 고장 요인에 대하여 분석하는 방법으로, 위험도(RPN)를 통해 관리할 수 있다. FMEA는 심각도, 발생도, 검출도가 같은 중요도로 평가되기 때문에 단점을 가진다. 퍼지 FMEA는 FMEA의 단점을 보완하기 위해 퍼지이론을 이용한 것이다. 퍼지 이론은 현상의 불확실한 상태를 표현해주는 방법으로, 정량적인 값을 제공한다. 본 논문에서, 퍼지 FMEA는 회전익 항공기 착륙장치의 고장 모드에 대한 객관적인 평가를 위해 적용되었다. 착륙장치에 대한 위험도 분석을 위해, 퍼지 규칙과 소속 함수를 구성하였다. 퍼지화 모델은 심각도, 발생도, 검출도의 크리스프(crisp) 값을 이용하였고, 위험도를 도출하였다. 착륙장치에 대한 퍼지 FMEA 결과는 위험도와 우선순위를 분석할 수 있다. 퍼지 FMEA는 회전익 항공기의 품질 보증 활동에서 기초자료로 활용할 수 있음을 확인하였다.

• 전기학회논문지
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• 제60권7호
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• pp.1314-1323
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• 2011

The maintenance of generating units is implicitly related with power system reliability and has a tremendous bearing on the operation of the power system. A technique using a fuzzy search method which is based on fuzzy multi-criteria function has been proposed for GMS (generator maintenance scheduling) in order to consider multi-objective function. In this study, a new technique using combined fuzzy set theory and genetic algorithm(GA) is proposed for generator maintenance scheduling. The genetic algorithm(GA) is expected to make up for that fuzzy search method might search the local solution. The effectiveness of the proposed approach is demonstrated by the simulation results on a practical size test systems.

• 품질경영학회지
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• 제23권3호
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• pp.156-166
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• 1995

Job shop scheduling problem is a complex system and an NP-hard problem. Thus it is natural to look for heuristic method. We consider the multi-part production scheduling problem for quality level in a job shop scheduling under the existence of alternative routings. The problem is more complex if the processing time is imprecision. It requires suitable method to deal with imprecision. Fuzzy set theory can be useful in modeling and solving scheduling problems with uncertain processing times. Li-Lee fuzzy number comparison method will be used to compare processing times that evaluated under fuzziness. This study presents heuristic method for quality level in bottleneck-based job shop scheduling under fuzzy environment. On the basis of the proposed method, an example is presented.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.186-192
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• 2014

Recently wind energy penetration into power systems has increased. Wind power, as a renewable energy source, plays a different role in the power system compared to conventional power generation units. As long as only single and small wind power units are installed in the power system, wind power does not influence power system operation and can easily be integrated. However, when wind power penetration reaches a significantly high level and conventional power production units are substituted, the impact of wind power on the power system becomes noticeable and must be handled. The connection of large wind turbines and wind farms to the grid has a large impact on grid stability. The electrical power system becomes more vulnerable to and dependent on wind energy production, and therefore there is an increased concern about the large wind turbines impact on grid stability. In this work, a new type of fuzzy logic controller for the frequency control of wind farms is proposed and its performance is verified using SimWindFarm toolbox which was developed as part of the Aeolus FP7 project.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.717-720
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• 2006

In this study, we predicted locations vulnerable to ground subsidence hazard using fuzzy logic and geographic information system (GIS). Test was carried out at an abandoned underground coal mine in Samcheok City, Korea. Estimation of relative ratings of eight major factors influencing subsidence and determination of effective fuzzy operators are presented. Eight major factors causing ground subsidence were extracted and constructed as a spatial database using the spatial analysis and the probability analysis functions. The eight factors include geology, slope, landuse, depth of mined tunnel, distance from mined tunnel, RMR, permeability, and depth of ground water. A frequency ratio model was applied to calculate relative rating of each factor, and the ratings were integrated using fuzzy membership function and five different fuzzy operators to produce a ground subsidence susceptibility map. The ground subsidence susceptibility map was verified by comparing it with the existing ground subsidences. The obtained susceptibility map well agreed with the actual ground subsidence areas. Especially, ${\gamma}-operator$ and algebraic product operator were the most effective among the tested fuzzy operators.