• Journal of the Korean Mathematical Society
• /
• v.53 no.5
• /
• pp.1101-1114
• /
• 2016

Let ($M^{2n+1}$, ${\phi}$, ${\xi}$, ${\eta}$, g) be a (k, ${\mu}$)'-almost Kenmotsu manifold with k < -1 which admits a gradient Ricci almost soliton (g, f, ${\lambda}$), where ${\lambda}$ is the soliton function and f is the potential function. In this paper, it is proved that ${\lambda}$ is a constant and this implies that $M^{2n+1}$ is locally isometric to a rigid gradient Ricci soliton ${\mathbb{H}}^{n+1}(-4){\times}{\mathbb{R}}^n$, and the soliton is expanding with ${\lambda}=-4n$. Moreover, if a three dimensional Kenmotsu manifold admits a gradient Ricci almost soliton, then either it is of constant sectional curvature -1 or the potential vector field is pointwise colinear with the Reeb vector field.

• School Mathematics
• /
• v.13 no.1
• /
• pp.127-153
• /
• 2011

The purpose of this study was to investigate the effect of peer tutoring on mathematical inclination and mathematical communication ability of peer tutor. For the purpose of this study, research questions were established as follows: 1. How does peer tutoring affect to the mathematical inclination of peer tutors? 2. How does peer tutoring affect to the mathematical communication ability of peer tutors? To answer the research questions, four 5th grade peer tutors were selected for qualitative case study in an elementary school located in Goyang-si, Gyeonggi-do. Before and after 11 weeks of peer tutoring in their mathematics classes, mathematical inclination, mathematical communication ability of peer tutors were examined. For qualitative analysis, peer tutors were asked to complete worksheets, self-evaluation, journal for their peer tutoring in daily basis during the experiment. By comparing the scores in mathematical inclination test and mathematical communication test before and after the treatment and analyzing the data gathered for qualitative analysis, the conclusions were drawn as follows: First, Peer tutoring has positive effects on the mathematical inclination of peer tutors. Scores for mathematical inclination of peer tutors after the treatment increased and qualitative analysis showed positive change in their attitude toward mathematics. Second, Peer tutoring has positive effects on the mathematical communication ability of peer tutors. Scores in the performance assessment for mathematical communication ability of peer tutors after the treatment increased. Also qualitative analysis showed that peer tutors tried to develop various ways to solve a problem and explained them to their peer tutee sophisticatedly.

• Communications for Statistical Applications and Methods
• /
• v.25 no.3
• /
• pp.245-261
• /
• 2018

Attempts have been made to define new classes of distributions that provide more flexibility for modelling skewed data in practice. In this work we define a new extension of the generalized gamma distribution (Stacy, The Annals of Mathematical Statistics, 33, 1187-1192, 1962) for Marshall-Olkin generalized gamma (MOGG) distribution, based on the generator pioneered by Marshall and Olkin (Biometrika, 84, 641-652, 1997). This new lifetime model is very flexible including twenty one special models. The main advantage of the new family relies on the fact that practitioners will have a quite flexible distribution to fit real data from several fields, such as engineering, hydrology and survival analysis. Further, we also define a MOGG mixture model, a modification of the MOGG distribution for analyzing lifetime data in presence of cure fraction. This proposed model can be seen as a model of competing causes, where the parameter associated with the Marshall-Olkin distribution controls the activation mechanism of the latent risks (Cooner et al., Statistical Methods in Medical Research, 15, 307-324, 2006). The asymptotic properties of the maximum likelihood estimation approach of the parameters of the model are evaluated by means of simulation studies. The proposed distribution is fitted to two real data sets, one arising from measuring the strength of fibers and the other on melanoma data.

• Journal of the Korean School Mathematics Society
• /
• v.3 no.1
• /
• pp.149-163
• /
• 2000

The Ministry of Education have had us practice the performance test as a substitute proposal, however, all the more for the idealistic purport, our education front does not have such a sufficient condition as to practice the performance test for many classes and miscellaneous duties and over-populated class, and that practice has been enforced so abruptly without any drastic preparation and has caused much confusion from the beginning of that enforcement. Thus, these problematic concerns are remained as the tasks of the teachers to be solved by themselves in the front of education, and herein I came to do this research. The followings are the conclusions that I got as the results of the research (1) Performance test style should be applied in consideration of the students' achievement level and the gap of the teachers' recognition; descriptive test, portfolio assignment and formative test styles were proper for the students lacking basic study ability. (2) Descriptive test should have its beginning with the question items to which students can write the problem solving procedure logically rather than those to evaluate the creation ability and thinking ability: and putting down specifically the assessment standard could prevent students' confusion and scheme the impartiality of the assessment. (3) Portfolio assignment evaluation should be given with as interesting and suitable amounts as possible so that the students can do by themselves. (4) Utilizing the performance test table enabled easy management of documentary evidence. And it is needless to say that the success of the performance test should have preceding conditions like the teachers' understanding and their positive participation. Therefore, I'd like to give suggestions herein like the followings; (1) The performance test should not always be made into grades, and there is a need to develop the test gradually in the condition that the education surroundings permit by checking time, frequency, ratio and contents of the test while practicing the multiple choice writing test. (2) As long as the performance test has the aims of improving the studying and learning activities, any performance test only for the sake of making numerals with the thought that assessment is the disposal of the grades should be avoided, and the change of the lecturing styles and development of various assessing types and studying materials should be endeavored to confirm with the aims.

• Journal of Elementary Mathematics Education in Korea
• /
• v.15 no.1
• /
• pp.141-159
• /
• 2011

The purpose of the present research is to suggest implications on guidance of height concept understanding of figures by investigating concept understanding how sixth grade's elementary school students understand a height concept of figures. In order to achieve this research purpose, a height concept understanding test of figures was carried out with the target of 54 sixth grade students who already learned a height concept of plane figures and three-dimensional solid figures and thus this research analyzed characteristics and errors appeared there. When analyzing its characteristics and errors interviews with students were carried out for in-depth analysis. And as a result the following implications could be obtained. First, students felt more difficulty in measuring height in a figure that its lower base is not horizontal in questions measuring height of a plane figure. Second, there were cases that students associate a height concept of figures with experience of height experienced in daily life. Third, students were feeling difficulty in linguistically expressing a concept called height that oneself has. Expressing a concept linguistically plays an important role in understanding a concept clearly. Accordingly activities for raising this mathematical communication ability are required, Fourth, the present research can suggest implications in designing classes that students can clearly understand the height concept of figures.

• Journal of Elementary Mathematics Education in Korea
• /
• v.20 no.4
• /
• pp.655-676
• /
• 2016

The purpose of this study is to examine the effects of teaching on functional thinking, one of the algebraic thinking in sixth grade students level. For this study, we developed functional thinking based-teaching through analyzing mathematical curriculum and preceding research, which consisted of 12 classes, and we investigated the effects of teaching through quantitative and qualitative analysis. In the results of this study, functional thinking based-teaching was statistically proven to be more effective in improving algebraic reasoning skills and lower elements which is an algebraic reasoning as generalized arithmetic and functional thinking, compared to traditional textbook-centered lessons. In addition, the functional thinking based-teaching gave a positive impact on the functional thinking level. Thus functional thinking based-teaching provides guidance on the implications for teaching and learning methods and study of the functional thinking in the future, because of the significant impact on the mathematics learning in six grade students.

• Communications of Mathematical Education
• /
• v.36 no.1
• /
• pp.1-21
• /
• 2022

The purpose of this study is to analyze the current situation of EduTech, which is proposed as a way to build a flexible learning environment regardless of time and place according to the use of digital technology in mathematics subjects. The process of designing classes to use the EduTech platform, which is still in the development introduction stage, in public education is still difficult, and research to observe its effects and characteristics is also in its early stages. However, in the stage of preparing for future education, it is a meaningful process to grasp the current situation and point out the direction in preparation for the future in which EduTech will be actively applied to education. Accordingly, the current situation and utilization trends of EduTech at home and abroad were confirmed, and the functions and roles of EduTech platforms used in mathematics were analyzed. As a result of the analysis, the EduTech platform was pursuing learners' self-directed learning by constructing its functions so that they could be useful for individual learning of learners in hierarchical mathematics education. In addition, we have confirmed that the platform is evolving to be useful for teachers' work reduction, suitable activities, and evaluations learning management. Therefore, it is necessary to implement instructional design and individual customized learning support measures for students that can efficiently utilize these platforms in the future.

• Communications of Mathematical Education
• /
• v.36 no.3
• /
• pp.397-415
• /
• 2022

The purpose of this study is to analyze the discourse structure of teachers that can help students participate in class by using mathematical metaphors that can arouse students' interest and motivation. In order to achieve this goal, we observed a semester class of a career teacher who practiced pedagogy that connects students' experiences with mathematical concepts to motivate students to learn and promote participation. Among the metaphors that the study target teachers used in a variety of mathematical concepts and problem-solving processes during the semester, we extracted the two class examples that can help develop teaching methods using metaphors. Representatively selected two classes are one class example using metaphors and, the other class example using metaphors and expanding and applying problems. As a result of analysis, the structure of teacher discourse that uses metaphors and expands and applies problems by linking students' experiences with mathematical content was found to help solve a given problem and elaborate mathematical concepts. As a result of the analysis, the discourse structure of teachers using mathematical metaphors based on communication with students could provide implications for the development of teaching methods for the recovery of mathematics education.

• School Mathematics
• /
• v.13 no.4
• /
• pp.675-696
• /
• 2011

This study was designed to understand PCK to improve professionalism of teachers and derive implications about proper teachings methods. For achieving these research purposes, different PCK and teaching methods in class of three teachers were compared and analyzed targeting arithmetic operation unit of fraction. For this study, criteria of PCK analysis of teachers was set, PCK questionnaires were produced and distributed, teachers had interviews, PCK of teachers were analyzed, two times fraction class was observed and analyzed, and PCK of teachers and their classes were compared. Followings are results to analyze PCK of teachers about fraction. In relation to PCK of three teachers, first of all, A teacher accurately understood concepts of fraction and learners' errors that may occur when they study fraction. Also, he(she) proposed concrete teaching strategies for fraction based on manipulated materials. B teacher also understood concepts of fraction and learners' errors accurately too. On the other hand, C teacher laid stress on knowledge to stress principles and taught that they are bases for every class. These results mean that self-training and inservice- training should be efficiently upgraded to improve PCK of teachers.

• Journal of The Korean Association of Information Education
• /
• v.21 no.2
• /
• pp.199-208
• /
• 2017

The present study investigates the potential of an educational programming game as a strategy for enhancing effective domains of mathematics curriculum, which has been criticized as a problem of education in Korea. The process of programming Fortress, an educational game, in conjunction with the lesson on the trigonometric function as part of the middle school mathematics curriculum, was designed for instruction and learning, and its effectiveness was tested. The study was conducted using a nonequivalent pretest-posttest experimental design. Research procedures included the following steps: (1) both the experimental and the comparison groups participated in four classes to understand and apply the concept of the trigonometric function, and (2) the experimental group participated in Fortress game programming activities using Scratch, which was designed in this study, while the comparison group participated in solving a real-life trigonometric problem - calculating the height of a building using the concept of trigonometry. The results of the t-test showed that students' interest and perceived value of the mathematics curriculum were significantly higher in the experimental group than in the comparison group. However, the results of analysis of covariance (ANCOVA) using pretest scores of the interest and perceived value showed the influence of pretest scores on posttest scores for the interest level, although the effect of the experiment on the perceived value of the mathematics curriculum was more significant.