• 대한인간공학회지
• /
• 제19권2호
• /
• pp.87-99
• /
• 2000

This study aims to examine a fuzzy logic-based human expert EMG prediction model (FLHEPM) for predicting electromyographic responses of trunk muscles due to manual lifting based on two task (control) variables. The FLHEPM utilizes two variables as inputs and ten muscle activities as outputs. As the results, the lifting task variables could be represented with the fuzzy membership functions. This provides flexibility to combine different scales of model variables in order to design the EMG prediction system. In model development, it was possible to generate the initial fuzzy rules using the neural network, but not all the rules were appropriate (87% correct ratio). With regard to the model precision, the EMG signals could be predicted with reasonable accuracy that the model shows mean absolute error of 8.43% ranging from 4.97% to 13.16% and mean absolute difference of 6.4% ranging from 2.88% to 11.59%. However, the model prediction accuracy is limited by use of only two task variables which were available for this study (out of five proposed task variables). Ultimately, the neuro-fuzzy approach utilizing all five variables to predict either the EMG activities or the spinal loading due to dynamic lifting tasks should be developed.

• 대한수학회논문집
• /
• 제12권3호
• /
• pp.769-778
• /
• 1997

In this paper, we obtain a strong law of large number for sums of level-wise independent and level-wise identically distributed fuzzy random variables.

• Korean Journal of Mathematics
• /
• 제16권4호
• /
• pp.537-543
• /
• 2008

Guan and Li [2] obtained SLLN for weighted sums of level-wise independent fuzzy random variables. In this paper, a generalization of Guan and Li [2] is obtained by using the Skorokhod metric on F(R).

• 제어로봇시스템학회논문지
• /
• 제6권6호
• /
• pp.433-440
• /
• 2000

To flexibly evaluate performance and reliability of a real-time system which is intrinsically characterized by stringent timing constraints to generate correct responses, we propose fuzzyrandom variables and build a discrete event model embedded with fuzzy-random variables. Also, we adapt fuzzy-variables to a path-space approach, which derives the upper and lower bounds of reliability by using a semi-Markov model that explicitly contains the deadline information. Consequently, we propose certain formulas of state automata properly transformed by fuzzy-random variables, and present numerical examples applying the formulas to RTP(Rapid Thermal Process) to show that a complex system can be properly evaluated based on this model by computer simulation.

• Journal of the Korean Statistical Society
• /
• 제31권1호
• /
• pp.129-140
• /
• 2002

In this paper, we obtain a strong law of large numbers for convex tight random elements taking values in the space of fuzzy numbers in R.

• 대한기계학회논문집A
• /
• 제21권3호
• /
• pp.361-368
• /
• 1997

In order to eliminate position errors existing at the steady state in the motion control of robotic manipulators, a new fuzzy control algorithm is propeosed using three variables, position error, velocity error and integral of position errors as input variables of the fuzzy controller. Although the number of input variables of the fuzzy controller is increased from two to three, the number of fuzzy control rules is just increased by two. Three dimensional look-up table is used to reduce the computational time in real-time control, and a technique reducing the amount of necessary memory is introduced. Simulation and experimental studies show that the position errors at the steady state are decreased more than 90% compared to those of existing fuzzy controller when the proposed fuzzy controller is applied to the 2 axis direct drive SCARA robot manipulator.

• 한국지능시스템학회논문지
• /
• 제17권3호
• /
• pp.355-367
• /
• 2007

본 논문에서는 설계변수와 제어기 이득의 자기 동조를 사용한 PI+D 제어기 설계법을 제안한다. 사용된 퍼지 PI+D 제어기는 일반적인 연속 시간 선형 PI+D 제어기를 근사화하여 사용하였고, 퍼지화는 퍼지싱글톤으로, 비퍼지화는 간략화된 무게중심법을 사용하였다. 퍼지추론 결과는 분리된 퍼지 변수로서 다른 작용 성분으로 계산되고, 그 결과는 설계변수에 해당하는 함수의 형태로 결정되어 제어이득을 결정한다. 따라서 제안된 방법은 빠른 동조 성능을 가지며, 퍼지 입력변수의 증가에도 쉽게 적용될 수 있고, 재생 오차를 줄이는 이점을 가진다. 이 제어기는 설계변수와 제어기 이득의 사용으로 보다 높은 효율성과 개선점을 가지고 있다.

• Journal of the Korean Data and Information Science Society
• /
• 제14권1호
• /
• pp.75-82
• /
• 2003

In this paper, a general convergence theorem of fuzzy random variables is considered. Using this result, we can easily prove the recent result of Joo et al. (2001) and generalize the recent result of Kim(2000).

• Journal of the Korean Data and Information Science Society
• /
• 제15권2호
• /
• pp.495-498
• /
• 2004

In this note, we consider several types of convergence theorems for the expected value of fuzzy variables defined by Liu and Liu [IEEE Trans. Fuzzy Systems, 10(2002), 445-450].

• 한국통계학회:학술대회논문집
• /
• 한국통계학회 2002년도 추계 학술발표회 논문집
• /
• pp.215-220
• /
• 2002

In this paper, we establish weak laws of large numbers for weighted sums of convex-compactly uniformly integrable fuzzy random variables taking values in the space of upper-semicontinuous fuzzy sets in R$^{p}$.