• Title/Summary/Keyword: function concept

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A Cross-National Study of Calculus Students' Understanding of the Funciton Concept (함수 개념의 이해에 대한 비교 연구)

  • 윤석임
    • Journal of Educational Research in Mathematics
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    • v.8 no.2
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    • pp.753-762
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    • 1998
  • This Paper reports results of investigating the relationship between students' perfoonance and mathematics imtructiooal system in understanding of the function concept. A written examination measuring calcullli students' understanding of the fimction concept was administered to two groups of students whose educatiooal oockground were different. One group consists of students who completed a pre-calculus course in Korea and the other group completed the same course in the United States. This study investigates how students in two groups acquire an understanding of major aspects of the function concept and provided interesting insights regarding the different background and belief related to their performance. Follow-up interviews were conducted to identify possible explanations for the different performance of the two groups in understanding the function concepts. Results indicate that the differences came from the educational environment and individual belief.

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An Analysis of Understanding Level of High School Students Shown in Trigonometric Functions (삼각함수에 대한 고등학생들의 이해 층위 분석)

  • Lee, Yu Bin;Cho, Cheong Soo
    • Communications of Mathematical Education
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    • v.33 no.3
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    • pp.319-334
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    • 2019
  • In this study, using the tasks related trigonometric functions, the degree of high school students' understanding of the function concept was examined through the level of Hitt(1998). First, the degree of the students' understanding was classified by level, then the concept understanding was reclassified by the process or the object. As a result, high school students' concept understanding showed incompleteness in three stages. It was possible to know that the process in the interpretation of the graph is the main perspective, and the operation of algebraic representation is regarded as important. Based on these results, it seems necessary to study the teaching-learning method which can understand trigonometric functions from various perspectives. It seems necessary to study a lesson model that can reach function concept's understanding level 5 that maintains consistency between problem solving and representation system.

Investigation to Teach Graphical Representations and Their Interpretations of Functions to Fifth Graders (함수의 그래프 표현 및 그래프 해석 지도 가능성 탐색 - 초등학교 5학년을 중심으로 -)

  • Lee, Hwa-Young;Ryu, Hyun-Ah;Chang, Kyung-Yoon
    • School Mathematics
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    • v.11 no.1
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    • pp.131-145
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    • 2009
  • This research was designed to investigate the possibility to teach function concept and graph representation of functions in explicit manner toward at elementary level. Eight class-hours instruction was given to four Grade 5(age 11) students, and dynamic geometry software GSP was partially used in the class. Results indicate that the students could conceptualize the function relation, interpret linear function graphs, recognize the meaning of their slopes, and discuss the relationships among linear graphs and real life situation. Results also indicate that GSP helped students to recognize the relation between dots and the linear graph clearly and that GSP-line graph did decisive role for children to understand the meaning of graph representation of function.

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Pitch Control for Wind Turbine System using Advanced PID Controller (개선된 PID 제어기를 이용한 Wind Turbine의 피치 제어)

  • Jeon, Jong-Hyun;Kwon, O-Shin;Kim, Jin-Sung;Heo, Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.831-836
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    • 2011
  • The study described in this paper is aimed to maintain a constant output of wind turbine system via pitch control of wind turbine using Advanced PID(APID) controller. In order to improve dynamic response characteristic in terms of pitch angle and disturbance reject, the APID controller is developed. The structure of the APID is composed with derivative P controller and new type of integral control action. This new improved integral control has concept of error window and weight function concept. The performance of the APID control technique is compared with those of conventional ones via simulation. Simulation results show that the proposed method is effective and enhanced the dynamic performance of the system.

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Study on the Hydrofilm Extrusion through Conically Converging Dies (원추형 금형을 통한 박막식 정수압 압출 에 관한 연구)

  • 신동헌;조남선;양동열
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.7 no.2
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    • pp.168-174
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    • 1983
  • The study is concerned with an analysis on the hydrofilm extrusion through conical dies. The upper bound method is adopted for the analysis of metal deformation in connection with hydrodynamic lubrication theory for the lubricant in order to determine the extrusion pressure for some variables such as reduction of area, die cone angle. In the upper bound method, a kinematically admissible velocity field is found by assuming proper streamlines and applying the flow function concept to the region of plastic deformation. The effect of work hardening is incorporated approximately by calculating the strains at the exit of the die. The experiments are carried out with the commercially pure aluminium for some chosen variables at room temperature. It is shown that the theoretical predictions are in good agreement with the experimental observations.

A Study on the Teaching of 'Function' utilizing the Graph Art - Case study focusing on the activities of Ulsan WISE Science Camp - (Graph Art를 활용한 함수 지도에 관한 연구 - 울산 WISE 과학캠프활동을 중심으로 한 사례연구 -)

  • Chung, Young-Woo;Kim, Boo-Yoon
    • The Mathematical Education
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    • v.51 no.3
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    • pp.197-210
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    • 2012
  • In this study, we will develop and implement the teaching program of 'Function', on the subject of "Poster-Making utilizing the Graph Art" in the Math Camp for middle-school students. And we will examine the didactical significance through student's activities and products. The teaching program of 'Function' utilizing the Graph Art can be promoted self-directly the understanding of 'Function' concept and the ability for handling 'Function'. In the process of drawing up the graph art, in particular, this program help students to promote the ability for problem-solving and mathematical thinking, and to communicate mathematically and attain the his own level. Ultimately, this program have a positive influence upon cognitive and affective and areas with regard to mathematics.

Assessment of Ventricular Function Using Gated Blood Pool Scan and Gated Blood Pool SPECT (게이트심장혈액풀 스캔과 게이트심장혈액풀 SPECT를 이용한 심실기능의 평가)

  • Park, Seok-Gun
    • The Korean Journal of Nuclear Medicine
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    • v.39 no.2
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    • pp.100-106
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    • 2005
  • Non-invasive evaluation of cardiac function by nuclear medicine technologies are one of the major contribution of nuclear medicine. Gated cardiac blood pool scan was once a novel and robust technique which enabled evaluation of ventricular function. Concept of EKG gating was one of the major breakthrough in nuclear cardiology. According to the evolution of echocardiographic techniques, and as the evaluation of myocardial perfusion by perfusion SPECT became feasible, number of gated blood pool study dong in nuclear medicine laboratory is declining. And recently, evaluation of ventricular function with gated perfusion SPECT further decreased the use of gated blood pool scan. In this article, assessment of ventricular function using gated blood pool scan is discussed including some insight about the role of gated blood pool SPECT.

On Some Teaching Problems Related to the Learning of Variable Concept in School Mathematics (학교 수학의 변수 개념 학습과 관련된 몇 가지 지도 문제에 대하여)

  • 김남희
    • School Mathematics
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    • v.1 no.1
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    • pp.19-37
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    • 1999
  • In this study, we examined some matters related to the learning of variable concept in school mathematics on the basis of the theoretical foundation from the previous studies(e.g. Davis, 1975; Rosnick, 1981; IK chemann, 1981; Wagner, 1983.) and practices on variable concept teaching by evaluating the current state of that. Matters be discussed are as follows; the use of symbol for place holders in elementary mathematics, the dealing with sets those elements are literals and operations of such sets, the teaching of dummy variable, the construction of literal expressions that contains variables, the labeling indeterminates as a constant, the change in the exact meaning of variable according to the function concept, the teaching of a generalization by means of variables. After considering on these matters that are connected with the teaching-learning of variable concept, we suggested the alternative proposal to the current state of variable concept teaching.

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An Advanced Simulation Model for Brushless DC Motor Drives

  • Lee B. K.;Ehsani M.
    • Proceedings of the KIPE Conference
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    • pp.390-394
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    • 2001
  • A dynamic simulation model for the brush less dc (BLDC) motor drives using Matlab is presented. In this model, an entire BLDC motor drive, including power conversion unit, BLDC motor, and speed/torque control system, is investigated. Especially, the PWM inverter is modeled using switching function concept, so that the detailed voltage and current waveforms, such as line-to-line voltages, inverter input current, ac line current, and switch/diode currents, can be obtained and average/rms ratings of the components can be easily calculated. Also, the proposed model is made into modular blocks and it can be easily extended to other ac motor applications with a little modification. The detailed modeling method is explained and its actual implementation is described. The validity of the proposed model is verified by various simulation results.

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Mechanical and thermal stability investigation of functionally graded plates resting on elastic foundations

  • Houari, Ali;Benguediab, Mohamed;Bakora, Ahmed;Tounsi, Abdelouahed
    • Structural Engineering and Mechanics
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    • v.65 no.4
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    • pp.423-434
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    • 2018
  • In present work, both the hyperbolic shear deformation theory and stress function concept are used to study the mechanical and thermal stability responses of functionally graded (FG) plates resting on elastic foundation. The accuracy of the proposed formulation is checked by comparing the computed results with those predicted by classical plate theory (CPT), first-order shear deformation theory (FSDT) and higher-order shear deformation theory (HSDT). Moreover, results demonstrate that the proposed formulation can achieve the same accuracy of the existing HSDTs which have more number of governing equations.