• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.37-42
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• 2004

End-milling have been widely used in aircraft, automobile part and moulding industry. However, various working factors such as spindle speed, feed rate and depth of cut in end-milling have an effect on spindle vibration. There it is demanded the quantitative analysis of spindle vibration in order to get the optimum surface roughness. This study was carried out to analyze an influence of working factors on spindle vibration by design of Experiment. The results are shown that mathematical model of regression equation for an influence of working factors on vibration acceleration of spindle in end-milling by regression analysis is presented.

• Research in Mathematical Education
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• v.14 no.4
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• pp.347-360
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• 2010

Motivating students to study mathematics is a concern for many mathematics educators. In this paper, we present the outcome of a one semester experiment in which group-work and academic advising were used as teaching strategies in order to improve the motivational level of our students in learning mathematics. Although the students' performance did not show any statistically significant difference between the experimental and control groups, qualitative and other quantitative data collected indicate that the participants in the experiment, especially weak students, have in one way or the other benefited from the teaching approaches. Details of the experiment, the findings and their educational implications are presented.

• Communications of Mathematical Education
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• v.30 no.3
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• pp.309-333
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• 2016

This study is part of app development research based on user centered design which targets silver generation learners. The mathematical contents provided by Senior math application focus on Numeracy issues. In order to finalize the user interface and the mathematical contents which is for developing the mathematic application, teaching experiment was carried out through 9 senior learners. Also CIPP program evaluation model was used for monitoring the result of this teaching experiment. Factors such as 'educational objectives' 'requirement analysis' 'educational environment' 'curriculum' 'learning content' 'learning matter' 'interaction' 'program administration' 'supporting environment' 'satisfaction' 'study result' 'substantiality of learning' were checked and as a result the Senior Mathematic application was developed through these feedbacks.

• The Mathematical Education
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• v.54 no.1
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• pp.13-30
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• 2015

The mathematical object is conceptual. Thus we can not prove the property of mathematical object in experimental viewpoint but in conceptual viewpoint. We performed the experiment for 28 middle school students to investigate whether they understand this. As a result, the majority of student didn't cognize the limit of experimental method. We had also individual interviews with four students. As results, one student was exactly cognizing the limit of experimental method, but he couldn't prove logically. The others didn't cognize the limit of experimental method. They thought that the proposition was already true regardless of the error. And one of them even thought that to be equal approximately was the same of to be equal exactly. Also, one student has confused between the experimental viewpoint and the conceptual viewpoint. This implies that it is necessary to help students understand the limit of experimental method.

• Bulletin of the Korean Mathematical Society
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• v.35 no.3
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• pp.473-484
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• 1998

We consider a finite difference approximation to a singular boundary value problem arising in the study of a nonlinear circular membrane under normal pressure. It is proved that the rate of convergence is $O(h^2)$. To obtain the solution of the finite difference equation, an iterative scheme converging monotonically to the solution of the finite difference equation is introduced. And the numerical experiment of this method is given.

• Journal of the Korean Mathematical Society
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• v.43 no.5
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• pp.1081-1098
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• 2006

Mathematical analysis is made on a mesh free method for the compressible Euler equations. In particular, the Moving Least Square Reproducing Kernel (MLSRK) method is employed for space approximation. With the backward-Euler method used for time discretization, existence of discrete solution and it's $L^2-error$ estimate are obtained under a regularity assumption of the continuous solution. The result of numerical experiment made on the biconvex airfoil is presented.

• Journal of Families and Better Life
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• v.30 no.6
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• pp.115-127
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• 2012

This study's aim was to analyze the effect of a project activity based on role play on 5-year-olds' mathematical ability. The participants of this study were 56 5-year-olds from two educational institutions for young children located in two metropolitan cities in Korea. The experimental group (n=28) participated in a project activity based on role play, while the comparative group (n=28) did not. The "Mart Play" project activity based on role play was developed emergently by the children and teachers of the experimental group. The children's mathematical ability was measured before and after the experiment. The data were analyzed using t-test and ANCOVA. As a result, the project activity based on role play had an effect on the improvement of 5-year-olds' mathematical ability generally, but not on their measurement ability.

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.3
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• pp.323-345
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• 2015

This study is intended to establish and apply a program created with RME for mathematising instruction and learning and identify how it influences on the mathematical thinking process in the field. In order to deal with this study inquiries, related theories have been analyzed establishing a program for mathematising instruction and learning method based on a model of them and RME theory principles and re-organizing education courses for instruction on the fields concerned. Study subjects were limited to two classes consisting of fifth graders in S elementary school located in the city of Daegu and divided them in an experiment group and a control group. An experiment group was given a mathematising learning method applied with RME, while a control group had a class with regular methods of learning and instruction during the period of experiment. As a summary of aforementioned results of the study, mathematising learning method applied with RME had an effect on improving mathematical thinking ability for students and also on promoting mathematising outcome through a repetitive experience in each procedure obtained on a regular basis.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.328-341
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• 2010

The authors adopt the Unmanned Undersea Vehicle(UUV), which has taken the shape of manta(Sohn et al. 2006). They call here it Manta-type Unmanned Undersea Test Vehicle(MUUTV). MUUTV is designed with the similar concept of UUV called Manta Test Vehicle(MTV), which was originally built by the Naval Undersea Warfare Center, USA(Lisiewicz and French 2000, Sirmalis et al. 2001, U.S. Navy 2004). The present study deals with evaluation of extreme motion of MUUTV at large attack angles. Extreme motion contains, for example, rising and depth change due to operation of hovering thrusters attached to MUUTV, lateral motion due to ocean current applied to MUUTV at low advance velocity, and so on. Numerical simulation technique has been utilized. The previous mathematical model on manoeuvring motion of MUUTV(Bae et al. 2009a) is basically adopted. Based on the results of present model experiment on extreme motion, the mathematical model is revised and supplemented in order to describe extreme motion. The hydrodynamic derivatives related to extreme motion are obtained from present model experiment and the other derivatives are referred to previous work(Bae et al. 2009a).

• The Mathematical Education
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• v.47 no.1
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• pp.27-47
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• 2008

In this paper, we study the effect of writing activity as mathematical communication on the students's mathematics achievement, learning attitude, and mathematical tendency. For this purpose, we construct a experimental class and then analyze the students' change in those aspects after applying three-divided-note writing activity and colleague feedback on their works those students are in the experimental class. As a result of the experiment, we find that three-divided-note writing activity and colleague feedback made some significant changes on the students achievement in mathematics, learning attitude, but does not affect on mathematical tendency. We also offer some suggestions for further research. Firstly, the mathematical communication ability must be stressed in mathematics education. For this purpose, we need to develop the teaching and the evaluation method to use not only writing but also reading, speaking, and listening skills so that many teachers can apply this method easily to their classes. Second, we need to fix some realistic problems such as fair evaluation , the numbers of students per class, the numbers of lesson, and too much extra-work, and so on. Thirdly, we suggest to explore some methods for extending three- divided-note writing activity to evaluate mathematical essay and to study educational effects of colleague feedback on mathematics performance assessment.