• International Journal of Fuzzy Logic and Intelligent Systems
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• 제14권1호
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• pp.57-65
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• 2014

In this paper, we investigate the properties of L-lower approximation operators as a generalization of fuzzy rough set in complete residuated lattices. We study relations lower (upper, join meet, meet join) approximation operators and Alexandrov L-topologies. Moreover, we give their examples as approximation operators induced by various L-fuzzy relations.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.479-484
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• 1998

입력된 영상으로부터 추론된 정보 표를 지식베이스에 저장하여 결정해를 구하는데는 많은 탐색시간이 소비된다. 본 논문에서는 탐색 시간을 감소시키기 위해서 러프집합의 식별(classification)과 근사(approximation) 개념을 이용하여 추론된 정보를 동치 클래스(equivalence class)로 분류하여 간략화한다. 감소된 규칙, 즉 Core와 Reduct 리스트를 구하여 결정해를 검색하는데 탐색 시간을 감소시키는데 있다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.218-224
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• 1998

본 논문에서는 컬러 모니터용 전자관(CDT; Color Display Tube)의 편향 요크(DY; Deflection Yoke)의 제조 공정상 오차가 발생시키는 컨버전스의 오차를 보정하기 위하여 붙이는 페라이트 박판(Ferrite Sheet)의 위치를 결정하는 규칙을 생성하는 박판을 붙여야 하는지 판단한다. 이를 러프 집합 이론을 이용하여 컨버전스 값을 조건부 속성으로, 페라이트 박판의 위치를 판단부 속성으로 하여 판단 테이블을 만들고 이때 발생하는 몇 가지 문제를 해결하여 최소화된 규칙을 찾아내는 방안을 제안한다.

• 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.

• 한국정밀공학회지
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• 제9권1호
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• pp.96-105
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• 1992

A study on the construction of a CAD/CAM system operated by 16 Bit PC basic language, for machining sculptured surface of die, was carried out. The system consists of 2 steps i.e., process for geometric modelling by wire frame and process for machining data generation. Geometric modelling for sculptured surface is made by the point data fitting, parallel sweeping, normal sweeping and linear connection of cross section curve. Machining data are gained by cutter off-set of geometric model data and machining carried out by DNC. This system is to be proved enough for rough cutting by actual machining experiment. But, for becoming a high level system, another method of cutter off-set has to be regarded and system must be reconstructed by another program language.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.29.2-29
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• 2001

For the design of human-centered systems in which a human and machine such as a robot form a human-in system, human-friendly interaction/interface is essential. Human-friendly interaction is possible when the system is capable of recognizing human biosigns such as5 EMG Signal, hand gesture and facial expressions so the some humanintention and/or emotion can be inferred and is used as a proper feedback signal. In the talk, we report our experiences of applying the Soft computing techniques including Fuzzy, ANN, GA and rho rough set theory for efficiently recognizing various biosigns and for effective inference. More specifically, we first observe characteristics of various forms of biosigns and propose a new way of extracting feature set for such signals. Then we show a standardized procedure of getting an inferred intention or emotion from the signals. Finally, we present examples of application for our model of rehabilitation robot named.

• 한국인터넷방송통신학회논문지
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• 제11권3호
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• pp.181-188
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• 2011

무선 네트워크와 모바일 컴퓨팅 응용의 급속한 보급과 더불어, 최근 네트워크 보안의 배경도 많은 변화를 가져왔다. 특히 이동성이 높은 차량 노드들로 네트워크 위상을 유지하는 차량 애드 혹 네트워크(Vehicular Ad Hoc Networks: VANETs)는 일반적으로 불안정한 통신 링크를 갖는 자기 조직화 P2P 망으로, 고정된 인프라 구조나 중앙 통제 라우팅 장비 없이 자동으로 망을 구성하고, 시간에 따라 고속으로 이동하며 망에 결합하거나 이탈하는 개방 망이므로 중앙 집중 제어 없이 누구나 접속이 허용되기 때문에 네트워크상에 해로운 비정상 행위 노드들에 대한 침입에 매우 취약하다. 본 논문에서는 VANETs에서의 노드들의 활동에 대한 비정상 행위를 효율적으로 식별하여 침입을 탐지할 수 있는 러프집합을 이용한 가중치 기반 침입탐지 방법을 제안하고, 그 성능을 모의실험을 통해 임계 허용 오차 ${\epsilon}$에 대한 비정상 행위로 인한 침입 탐지율과 거짓 경고율로 평가한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권9호
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• pp.4549-4567
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• 2016

To cope with the complex electromagnetic environment of wireless communication systems, anti-jamming decision methods are necessary to keep the reliability of communication. Basing on the rule-reduced genetic algorithm (RRGA), an anti-jamming decision method is proposed in this paper to adapt to the fast channel variations. Firstly, the reduced decision rules are obtained according to the rough set (RS) theory. Secondly, the randomly generated initial population of the genetic algorithm (GA) is screened and the individuals are preserved in accordance with the reduced decision rules. Finally, the initial population after screening is utilized in the genetic algorithm to optimize the communication parameters. In order to remove the dependency on the weights, this paper deploys an anti-jamming decision objective function, which aims at maximizing the normalized transmission rate under the constraints of minimizing the normalized transmitting power with the pre-defined bit error rate (BER). Simulations are carried out to verify the performance of both the traditional genetic algorithm and the adaptive genetic algorithm. Simulation results show that the convergence rates of the two algorithms increase significantly thanks to the initial population determined by the reduced-rules, without losing the accuracy of the decision-making. Meanwhile, the weight-independent objective function makes the algorithm more practical than the traditional methods.

• 한국지능시스템학회논문지
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• 제12권3호
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• pp.202-209
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• 2002

본 논문은 제어 시스템에서 규칙기반과 데이터 마이닝에서의 분류규칙의 명료함에 대해 다룬다. 대용량의 데이터로부터 유용한 정보를 얻어내는 데이터 마이닝은 중요한 이슈가 되고 있다. 인공지능에 기반을 둔 데이터 마이닝 분류기법에는 신경망, 의사결정나무 등 여러가지가 있지만 그 결과는 명확하고 이해하기 쉽고 분류규칙이 간단명료해야 한다. 러프집합이론은 불충분하고 비일관적인 데이터로부터 의미있는 지식을 추출하는데 효과적인 기법이고, 다양한 속성들을 효과적으로 사용함으로써 분류와 근사화에 대한 좋은 해법을 제시한다. 본 논문에서는 러프집합이론의 근사화를 이용하여 알갱이 속에 숨겨져 있는 지식들을 찾아내는데 있어 효과적인 접근을 하였으며, 최상위 레벨에 코어를 적용하여 계층적 분류를 함으로써 대량의 데이터를 효율적으로 처리할 수 있도록 하였다. 제안된 분류방법은 정보시스템의 해석을 용이하게 하고 최소의 분류규칙을 만든다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권3호
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• pp.361-366
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• 2018

Ice crushing occurs in many situations that involve a sliding frictional component such as sports involving ice-contact, ice interaction with ship hulls, and ice-on-ice sliding/crushing within glaciers and between interacting sea ice floes. Ice crushing-friction tests were conducted in the lab at $-10^{\circ}C$ using a set of acrylic ice-crushing platens that included a flat smooth surface and a variety of high-roughness surfaces with regular arrays of small prominences. The experiments were part of Phase II tests of the Blade Runners technology for reducing ice-induced vibration. Ice was crushed against the platens where the ice movement had both a vertical and a horizontal component. High-speed imaging through the platens was used to observe the ice contact zone as it evolved during the tests. Vertical crushing rates were in the range 10-30 mm/s and the horizontal sliding rates were in the range 4.14-30 mm/s. Three types of freshwater ice were used. Friction coefficients were extraordinarily low and were proportional to the ratio of the tangential sliding rate and the normal crushing rate. For the rough surfaces all of the friction coefficient variation was determined by the fluid dynamics of a slurry that flowed through channels that developed between leeward-facing facets of the prominences and the moving ice. The slurry originated from a highly-lubricating self-generating squeeze film of ice particles and melt located between the encroaching intact ice and the surfaces.