• Journal of Information Processing Systems
• /
• 제11권2호
• /
• pp.184-204
• /
• 2015

Fuzzy Formal Concept Analysis (FCA) is a mathematical tool for the effective representation of imprecise and vague knowledge. However, with a large number of formal concepts from a fuzzy context, the task of knowledge representation becomes complex. Hence, knowledge reduction is an important issue in FCA with a fuzzy setting. The purpose of this current study is to address this issue by proposing a method that computes the corresponding crisp order for the fuzzy relation in a given fuzzy formal context. The obtained formal context using the proposed method provides a fewer number of concepts when compared to original fuzzy context. The resultant lattice structure is a reduced form of its corresponding fuzzy concept lattice and preserves the specialized and generalized concepts, as well as stability. This study also shows a step-by-step demonstration of the proposed method and its application.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회 논문집
• /
• pp.1398-1402
• /
• 2005

Riverbank filtration is a natural process using alluvial aquifers to remove contaminants and pathogens in river water for the production of drinking water. In riverbank filtration, the understanding of contaminant transport is an important task for the production of high quality drinking water. This study investigates the transport behavior of hydrophobic organic contaminants when colloids (dissolved organic matter and bacteria) are present in the aquifer. A mathematical model for the transport of contaminants is developed and solved numerically for various situations. Results show that in the riverbank filtration the presence of DOM and bacteria enhances the mobility of contaminant significantly. Sensitivity analysis indicates that the distribution of the total aqueous Phase contaminant is significantly affected by distribution coefficients which account for affinity of solid or colloidal Phase to contaminant.

• 대한수학교육학회지:학교수학
• /
• 제3권2호
• /
• pp.373-399
• /
• 2001

The function is a basic and key concept to understand mathematical problems. However, many students have difficulties to expand the knowledge to other related concepts and to transfer the knowledge to real world problems. The reasons for the problem may be that the concept of function is taught by simplified and abstracted formula without fully understanding of the reasoning process. Also, the examples for the concepts are artificial and not related to students' experiences. Situated learning theory provides great implications to solve these problems. So, this study was designed to teach the concept of function more meaningful to students by appling situated learning theory. Thirty-eight middle school students were participated in this study. Students were provided the instruction designed according to the principles of situated learning theory. Then, they were asked to complete attitude survey questionnair and a performance assessment task. The result showed that the instruction based on situated learning theory was useful to Promote students' understanding and motivation for learning. More implications of the study was provided in the paper.

• 제어로봇시스템학회논문지
• /
• 제5권8호
• /
• pp.955-960
• /
• 1999

This paper describes the effect of impact configurations on a single robot manipulator. The effect of different configurations of kinematically redundant arms on impact forces at their end effectors during contact with the environment is investigated. Instead of the well-known impact ellipsoid, I propose an analytic method on the geometric configuration of the impact directly from the mathematical definition. By calculating the length along the specified motion direction and volume of the geometry, we can determine the characteristics of robot configurations in terms of both the impact along the specified direction and the ability of the robot withstanding the impact. Simulations of various impact configurations are discussed at the end of this paper.

• 한국수학교육학회지시리즈C:초등수학교육
• /
• 제8권1호
• /
• pp.23-32
• /
• 2004

It is not too much to say that problem solving is still the focus of school mathematics though the trend of mathematics education for ten year from the one of 1980 is problem solving and the one of mathematics education for ten year from the one of 1990 is standards and constructivism. There are so many crucial clues or methods in good problem solving but I think that one of them is a representation. So, the purpose of this study is to investigate what is the meaning of representation in general and why representation is so important in elementary mathematics learning, Moreover, I have analyzed the gifted children's thinking of representation which is appeared in the previous internet home task of 40 gifted children who are selected through the examination of 1st, 2nd with paper and pencil and 3rd with practical skill and interview and finally I have presented some examples of children's representation how they use representation to model, investigate and understand special concept more easily in elementary school mathematics class.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.492-495
• /
• 1997

This paper aims to derive a mathematical model of the dynamics of handling task in field robot which stable grasping and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraints of tight area-contacts on motion of the overall system is analyzed and a method of computer simulation for overall system of differential-algebraic equations is presented. Thirdly, simulation results are shown and the effects of geometric constraints of contact-area are discussed. Finally, it is shown that even in the simplest case of dual single D.O.F. manipulators there exists a sensory feedback from sensing data of he rotational angle of the object to command inputs to joint actuators and this feedback connection from sensing to action eventually realizes secure grasping of the object, provided that he object is of rectangular shape and motion is confined to a horizontal

• 한국정밀공학회지
• /
• 제13권9호
• /
• pp.104-113
• /
• 1996

In robot system, the robot manipulation needs the information of task and objects to be handled in possessing a variaty of positions and orientations. In the current industrial robot system, determining position and orientation of objects under industrial environments is one of major problems. In order to pick up an object, the roblt needs the information about the position and orientation of object, and between objects and gripper. When sensing is accomplished by pinhole model camera, the mathematical relationship between object points and their images is expressed in terms of perspective, i.e., central projection. In this paper, a new approach to determine the information of the supporting points related to position and orientation of the object using the robot vision system is developed and testified in experimental setup. The result will be useful for the industrial, agricultural, and autonomous robot.

• 아동학회지
• /
• 제23권1호
• /
• pp.71-85
• /
• 2002

This study examined the effects of different interaction styles, that is, interaction with an object and interaction with an adult, on young children's cognitive level. Subjects were 150 5-year-old children. The task required children to predict the working of a mathematical balance beam. Seven cognitive levels were identified based on the logic of prediction. Data were analyzed by t-test, F-test, Duncan Test and Wilcoxon Matched-Pairs Test. Results showed that both interaction styles caused improvement in children's cognitive level, but when interaction with an adult was divided into two categories, i.e., interaction with the higher group and interaction with the lower group, the latter experienced decline in cognitive level. Regardless of sex, interactions within the Zone of Proximal Development and with the object were found to be effective methods for children's cognitive improvement.

• 한국생산제조학회지
• /
• 제8권6호
• /
• pp.50-54
• /
• 1999

In the process of designing a wheel balancer an ergonomic evaluation model has shown that manual tire handling onthe machine was often the major problem, The root of the problem lay in the design of machine's shaft which is influenced by the opeative handling task. Several methods were reviewed for determining the correct shaft' sizes but the Revised NIOSH Equation and the Lifting Stress Calculator were found to be the only suitable models for this study. An application of these mathematical models has shoed that the shaft length and the shaft height were the most critical measurement By analyzing these conclusion s the correct shaft size parameters became clearly defined.

• Journal of Construction Engineering and Project Management
• /
• 제5권4호
• /
• pp.7-11
• /
• 2015

The luffing-tower crane (T/C) is a key facility used in the vertical and horizontal transportation of materials in a tall building construction. Locating the crane in an optimal position is an essential task in the initial stages of construction planning. This paper proposes a new optimization model to locate the luffing T/C in the optimal position to minimize the transportation time. A newly developed mathematical formula is suggested to calculate the transportation time of luffing T/C correctly. An optimization algorithm, the Harmony Search (HS) algorithm, was used and the results show that HS has high performance characteristics to solve the optimization problem in a short period of time. In a case study, the proposed model offered a better position for T/C than the previous heuristic approach.