• 연구논문집
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• s.23
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• pp.73-80
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• 1993

This study presents an intelligent PID control method based on the fuzzy logic and this method is applied to the active magnetic bearing system. By using an appropriate fuzzy matrix, some changes of values of the three coefficients of the controller are determined during system operation and these lead to the improvement of the transient and steady state behavior of the closed loop system. The presented method is actually a combination of the principles of PID control and fuzzy logic. Since the fuzzy logic using linguistic variables in place of numeric variables has many points of likeness to the human logic, the improvement in performance is notable especially in case of large nonlinearity and uncertainty such as the controller start and the excessive mass unbalance. A set of simulation and experimental results illustrate and considerable improvement in the control performance including small overshoot and small transient currents in magnet coils, while maintaining the overal static and dynamic characteristics near the equilibrium position.

• English Language & Literature Teaching
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• v.11 no.2
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• pp.1-18
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• 2005

This study is a preliminary investigation of the nature of discourse marker acquisition in Korean American speakers of English. Discourse markers are of interest because they are not an aspect of language taught through formal instruction either to native or non-native speakers. Therefore, discourse marker use serves as indirect evidence of face-to-face interaction with native speakers and an indicator of integration. In this light, the present study examines the presence of discourse markers in Korean Americans. The markers chosen for analysis were you know, like, and I mean. The data consist of spontaneous speech elicited from interviews. Sociolinguistic variables such as age, sex, and generation (i.e., $1^{st}$, 1.5, $2^{nd}$) were examined. Results show that there appears to be interaction between the variables and discourse marker use. While all speakers showed variable acquisition of markers, younger, female, and 1.5 generation speakers were found to use discourse markers more than other speakers. Although discourse marker use is optional and thus not a linguistic feature that must be necessarily acquired, it is clear that use is pervasive and acquired differentially by English speakers irrespective of whether they are native or not.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1264-1272
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• 1993

The software for unmanned control of three row typed rice combine has been developed using fuzzy logic. Three fuzzy variables were used : operating status of combine, steering, and speed. Eleven fuzzy rules were constructed and the eleven linguistic variables were used for the fuzzy rules. Six sensors were use of to get input values and sensor input values were quantified into 11 levels. The fuzzy output was infered with fuzzy inferrence which uses the correlation product encoding , and it must have been defuzzified by the method of center of gravity to use it for the control. The result of performance test using graphic simulation showed that the intelligently unmanned control of a rice combine was possible using fuzzy logic control.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1359-1361
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• 1996

This paper describes a design of real time fuzzy controller using Minimum fuzzy control Rule Selection Method(MRSM). The control algorithm of dynamic systems needs less computation time and memory. To reduce the computation time of fuzzy logic controller, minimum number of rules are to be selected for the fuzzy input variable. The universe of discourse is divided by the number of linguistic labels to allocate the assigned membership function to the fuzzy input variables. In this case, since fuzzy input variables are continuous, scale factor SU is tuned independently. According to increment of SU control surface is improved to adapt the change of system parameter. At this, crisp control surface is increased. With the increament of crisp control surface, fuzzy control surface is reduced. When error state deviates from desirable error state, crisp control surface is more useful than fuzzy control surface for obtaining fast rising time.

• The Mathematical Education
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• v.24 no.2
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• pp.74-104
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• 1986

This study aims at investigating the correlation between such variables as a child's family circumstance and personality and that of the child's mathematical ability. For the objects of the study five hundreds and sixteen students (male 273, female 243) were andomly selected from the fifth grade primary school students in the city of Seoul. For the tool of measure the investigation of Korean family circumstances with particular characteristics, the personality test by Chong Pom Mo and Kim Ho Kwon, and the intelligence test by Lee Sang Ro, Chin Whal Kyo and Pyon Chang Jin were employed. For the statistical analysis S. A. S. C., the statistical analysis package of KAIST was employed. The resutis of the test can be summarized as follows. The correlation between the variable of family Circumstance and that of mathematical alility 1) In case of the significance level 0.05 the education of the childs mother and the order of the child's birth have much to do with the perception speed. In case of the significance level 0.1 it makes some difference in the child's perception spead whether the clild's mother has a job or not. 2) In case of the significance level 0.05 the education of the child's father and mother, the father's job and the type of habitation have influence on the child's perception of space. 3) In case of the significance level 0.05 the education of the child's father and mother, the father's job, the order of the child's birth, the type of habitation, their religion, and their cultural, and economic standard have influence on the child's ability of inference. 4) In case of the significance level 0.05 the education of the child's father and mother, the father's job, the type of habitation, their religion and their cultural and economic standard have influence on the child's ability of calculation. 5) In case of the significance level 0.05 any variable of the child's family circumstance has nothing to do with the child's memory. In case of the significance level 0, 1 the type of family and the type of habitation have effect on the child's memory. 6) In case of the significance level 0.05 the education of the child's parents, the jobs of the parents, the type of habtation, their religion, and their cultural and economic standard have influence on the child's linguistic notion. The correlation between the variable of the child's personality and that of the child's mathematical ability 1) In regard to the priority of the variables influencing the child's perception speed, the child's discretion comes first in order, and then sociability and impulsiveness of the child. 2) The child's discretion has effect on the child's space perception. 3) The child's discretion has effect on the child's ability of inference. 4) In regard to the child's ability of calculation the child's discretion comes first in order, and then impulsiveness and sociability of the child. 5) The child's discretion has effect on memory. 6) The child's discretion has effect on the child's linguistic notion.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.10a
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• pp.3-8
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• 1998

The present work proposes the potential fuzzy framework, based on fuzzy set theory, for supporting decision-making problems, especially, selection problems of a best design in the area of nuclear energy system. The framework proposed is composed of the hierarchical structure module, the assignment module, the fuzzification module, and the defuzzification module. In the structure module, the relationship among decision objectives, decision criteria, decision sub-criteria, and decision alternatives is hierarchically structured. In the assignment module, linguistic or rank scoring approach can be used to assign subjective and/or vague values to the decision analyst's judgment on decision variables. In the fuzzification module, fuzzy numbers are assigned to these values of decision variables. Using fuzzy arithmetic operations, for each alternative, fuzzy preference index as a fuzzy synthesis measure is obtained. In the defuzzification module, using one of methods ranking fuzzy numbers, these indices are defuzzified to overall utility values as a cardinality measure determining final scores. According these values, alternatives of interest are ranked and an optimal alternative is chosen. To illustrate the applicability of the framework proposed to selection problem, as a case example, the best option choice of four design options under five decision criteria for primary containment wall thickening around large penetrations in an advanced nuclear energy system is studied.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.2
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• pp.157-165
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• 2015

The purpose of this study is to analyse literacy of children from multicultural backgrounds, and identify cognitive-linguistic predictors that can affect their literacy. First, the higher-grade students showed better cognitive-linguistic variables in reading and writing performance. Second, it has been noted that the predictor variable of reading in children from multicultural backgrounds was homeostasis in visual form, which is a sub-variable of visual perception. This implies that detained characteristics play an important role in reading prerequisite. Therefore it can be said that it is more important to recognise features and clues about the details than reading familiar words. Furthermore, learning consonants and vowels should come first rather than studying letters at the first stages of learning Korean.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.668-671
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• 1997

This paper describes a new process-plan selection method using a modified Fuzzy Quantification Theory(FQT). The problem for process-plan selection can be characterized by multiple attributes and used subjective, uncertain information. Fuzzy Quantification Theory is used for handling such informations because it is a useful tool when human judgment or evaluation is quantified via linguistic variables and the proposed method is concerned with the selection of a process plan by derivation of the values of categories for each attribute. In this paper, a modified Fuzzy Quantification Theory(FQT) is described and the procedure of this approach is explained and examples are illustrated.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.516-519
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• 1997

In this paper, the control of the temperature for the vehicle air conditioner is implemented with the fuzzy controller using a micro controller. The linguistic control rules of the fuzzy controller are separated into two out variables(multi input multi output ; MIMO) : one is those for the blower motor, and the other is those for air mix door. The error in fuzzy controller, the input variable is defined as difference between the reference temperature and the actual temperature in the cabin room. The fuzzy control rules are established from the human operator experience, and based engineering knowledge about the process. The method of the center of gravity is utilized for the defuzzification.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.9
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• pp.1071-1084
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• 1992

In this paper, the method for navigation and obstacle avoidance of the autonomous mobile robot is proposed. The proposed algorithms are based on the fuzzy inference system which is able to deal with imprecise and uncertain information. The self-tuning algorithm, which adopts the simplex method, modifies the parameters of membership functions of the input-output linguistic variables by changing the support of these fuzzy sets according to the integral of absolute error(IAE) of the system response. The wall-follwing navigation and obstacle avoidance of the mobile robot are based on range data measured from the internal sensors(encoder) and the outer sensors(sonar sensor). In addition, the algorithm for the obstacle detection proposed in this paper is based on the expert's experience. Finally, the effectiveness of navigation and obstacle avoidance algorithm is demonstrated through simulation and experiment.