• Communications of Mathematical Education
• /
• v.34 no.3
• /
• pp.277-297
• /
• 2020

The purpose of this study was to identify and compare the mathematics educational values of pre-service and in-service elementary school teachers. For this purpose, we implemented a questionnaire investigating mathematics educational values and used principal component analysis which resulted in six components. These components were named as fun, problem-solving, representation, computation, ability, and explanation through systematic labeling processes. Both pre-service and in-service elementary school teachers considered problem-solving the most important and there was no statistical difference between the teacher groups. They also considered fun the least important and in-service elementary school teachers regarded it more important than pre-service counterparts did. All value components except explanation were regarded as important by in-service elementary school teachers, fourth-year pre-service teachers, and first-year pre-service teachers in order. The result of noticeable differences between pre-service and in-service elementary school teachers implies that actual teaching experience may affect teachers' mathematics educational values more than teacher preparation programs. Based on these findings, we need to discuss what should be regarded as important and worthwhile in teacher preparation programs to establish mathematics educational values for pre-service teachers. We also need to confirm whether the mathematics educational values by in-service elementary school teachers may be in line with what has been pursued in the national mathematics curriculum.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.44 no.3
• /
• pp.64-69
• /
• 2007

Motion control of the system is a position control of motor. Motion control of an uncertain robot system is considered as one of the most important and fundamental research directions in the robotics. Some distinguished works using linear control, adaptive control, robust control strategies based on computed torque methodology have been reported. However, it is generally recognized within the control community that these strategies suffer from the following problems : the exact robot dynamics are needed and hard to implement, the adaptive control cannot guarantee the performance during the transient period for adaptation under the variation, the robust control algorithms such as the sliding mode control need information on the bounds of the possible uncertainty and disturbance. And it produces a large control input as well. In this dissertation, a motion control for the unmanned intelligent robot system using disturbance observer is studied. This system is affected with an impact vibration disturbance. This paper describes a stable motion control of the system with the consideration of external disturbance. To obtain the stable motion independently against the external disturbance, the disturbance rejection is strongly required. To address the above issue, this paper presents a Disturbance OBserver(DOB) control algorithm. The validity of the suggested DOB robust control scheme is confirmed by several computer simulation results. And the experiments with a motor system is performed to give the validity of applicability in the industrial field. This results make the easier implementation of the controller possible in the field.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.3
• /
• pp.49-55
• /
• 2017

In this study, gas turbine engine inlet duct was designed to satisfy uniform flow at aerodynamic interface plane (AIP). Haack-series was selected as nose cone profile and duct outer radius($r_o$) was designed to satisfy to match with area change rate between the nose cone and outer duct wall by the 1-D sizing. The design object of the inlet duct wall profile which has the gradual area change rate was uniform Mach number in the core flow region and minimum boundary later thickness at the both inner nose wall and outer duct wall. The flow characteristics inside the inlet duct was evaluated using CFD. The static pressure distribution at the AIP showed uniform pattern within 0.16%. Based on Mach number profile, the boundary layer thickness was 2% of channel height. Kiel temperature rake location was decided less than 100 mm in front of nose cone where the Mach number is less than 0.1 in order to maximize the temperature probe recovery rate.

• The Korean Journal of Archival Studies
• /
• no.65
• /
• pp.397-457
• /
• 2020

The purpose of this study is to assist in the overall understanding through detailed analysis of the ISO 30301:2019 standard, and to discuss the implications of the standard. To this end, this study first looked at the background of the revision of the ISO 30301 standard, and specifically outlined the process of establishing and revising the management systems for records family of standards by time. This study also looked at the HLS(High Level Structure) of the management system standard applied in the revised edition and the main revisions to the ISO 15489:2016 standard, as well as the emerging concept of 'Records requirements'. This study then compared revisions to the ISO 30301:2019 standard with the HLS of the management system standard and the ISO 30301:2011 standard. In addition, the main features of the revised edition of this standard were identified by analyzing new, enhanced, and changed requirements in the revised edition of ISO 30301. Based on this analysis, the amendments to this standard divided into four categories: expanding the records processes and realizing systematic record management, strengthening leadership and efficient management of the management systems for records, integrating and utilizing full-fledged other management system standards, and realizing flexible records management governance at the business process level.

• Research in Mathematical Education
• /
• v.7 no.3
• /
• pp.139-150
• /
• 2003

The purpose of this paper is to review the gifted education from a reflective perspective. Especially, this research touches upon the issues of selection process from a critical point of view. Most of the problems presented in the mathematics competition or in the programs for preparing such competitions share the similar characteristic: the circumstances that are given for questions are too artificial and complicated; problem solving processes are superficially and fragmentally related to mathematical knowledge; and the previous experience with the problem very much decides whether a student can solve the problem and the speed of problem solving. In contrast, the problems for selecting students for Gifted Education Center clearly show what the related mathematical knowledge is and what kind of mathematical thinking ability these problems intend to assess. Accordingly, the process of solving these problems can be considered an important criterion of a student's mathematical ability. In addition, these kinds of problems can encourage students to keep further interest, and can be used as tasks for mathematical investigation later. We hope that this paper will initiate further discussions on issues derived from the mathematically gifted student selection process.

• Communications of Mathematical Education
• /
• v.33 no.1
• /
• pp.1-19
• /
• 2019

This study deals with the case of student-centered discrete mathematics class with cyber lab. First, we provided lecture notes and cyber labs we developed. In particular, discrete mathematics is a course that covers the principles of algorithms. The purpose of this study is to provide students with basic mathematics, aiming to actively participate in the learning process, to improve their abilities and to reach the ultimate goal of student success with confidence. Second, based on interactions, students were able to prepare for the lectures, review, question, answer, and discussion through an usual learning management system of the school. Third, all the students generated materials through one semester, which were reported, submitted, presented and evaluated. It was possible to improve the learning effectiveness through the discussions and implementation of using some easy open source programming language and codes. Our discrete math laboratory could be practiced without any special knowledge of coding. These lecture models allow students to develop critical thinking skills while describing and presenting their learning and problem-solving processes. We share our experience and our materials including lecture note and cyber lab as well as a possible model of student-centered mathematics class that does not give too much of work load for instructors. This study shares a model that demonstrates that any professor will be able to have an individualized, customized, and creative discrete education without spending much of extra time and assistant, unlike previous research.

• Communications of Mathematical Education
• /
• v.33 no.1
• /
• pp.21-34
• /
• 2019

The purpose of this paper is to investigate the differences of the mathematics anxiety and mathematical achievement of high school students according to math socialization, and to find out which mathematics anxiety causes have more influence on mathematical achievement and how much it is. For this purposes, the problem of this study as follows: firstly, are there any relationship among mathematical grades, mathematics anxiety, interest and math socialization? secondly, are there any math socialization mathematics predict to mathematical grades, mathematics anxiety, interest? lastly, are there any differences in the mathematical grades, mathematics anxiety, interest according to math socialization level? The subjects of this study consist of 479 students selected for a class of unit, in high schools located in Seoul and metropolitan area, Korea. In this study, for students math socialization, Jung(2002)'s scale was used. Mathematical anxiety & interest, Huh(1996)'s Mathematics Anxiety Scale was used. The collected data were analyzed by using the 24.0 SPSS program. The data were also tested by using the t-test, pearson correlation and multiple regression. The major results of this study were as follows: firstly, math socialization, mathematics anxiety, interest and mathematical grades have significantly related each other, secondly, the multiple regression analyses demonstrated that sub factors of math socialization were the significant predictors of mathematical grades, mathematics anxiety and interest, lastly, mathematics grades, and mathematical anxiety and interest have significant differences depending on math socialization.

• The Mathematical Education
• /
• v.61 no.4
• /
• pp.613-629
• /
• 2022

This study explored the heterogeneous latent group on the influence of the learner's perceived math teaching method(instructor-centered, learner-centered) on math self-efficacy. In order to profile the characteristics of the detected latent group, the distribution of variables was confirmed, and multi-group analysis was conducted by SEM. According to the analysis results, two latent groups were detected, and the instructor-type group and the learner-type group were named. As a result of post-hoc analysis, the perception of instructor-centered classes and learner-centered classes, and the perception of math teaching ability were similar between the instructor-type and the learner-type group. But the instructor-type group had higher math self-efficacy, math interest, and math class engagement than the learner-type group. Also, in the instructor-type group, the effect of perception of math teaching ability on math self-efficacy and math class engagement was greater than that of the learner-type group. Whereas, in the learner-type group, the effect of math interest on math self-efficacy and math class engagement was greater than that of the instructor-type group. This study presented a new research method on the influence of math teaching methods on learners by applying the REBUS-PLS method.

• The Mathematical Education
• /
• v.61 no.4
• /
• pp.521-537
• /
• 2022

The unprecedented COVID-19 pandemic has disrupted, interrupted, and changed the way we normally prepare our teacher candidates in teacher preparation programs. In this paper, we, two mathematics teacher educators (MTEs), reflect our own experiences in appropriating, transforming, reconstructing, and modifying our pedagogies of teacher education in making a transition from face-to-face to online environment during the COVID-19 pandemic. Using a collaborative self-study, we discussed issues, challenges, changes, opportunities, and innovations of teaching an elementary mathematics methods course in the online environment. Using a constant comparison method, we explored the following three themes: (1) using virtual manipulatives; (2) creating collaborative, interactive, and shared learning experiences for preservice teachers; and (3) making preservice teachers engaged in student thinking. These findings indicated that online teaching requires transformative knowledge for teacher educators. Transferring face-to-face to online is not a simple matter of putting the existing content to online; it should focus on pedagogical improvement in teaching mathematics rather than technology's sake or how it can be repurposed in a new online environment in a way that students' learning is optimized. The findings of this study provide implications for unpacking MTEs' technological pedagogical content knowledge (TPACK), creating collaborative learning experiences for preservice teachers, and designing a collaborative self-study between MTEs engaged in the community of professional learning.

• Communications of Mathematical Education
• /
• v.36 no.2
• /
• pp.253-286
• /
• 2022

This study is a study in which four teachers from the same school who participated in a teacher learning community program at the school field developed interdisciplinary linkage and convergence data using Plato as a collaborative circle in ethics and mathematics subjects. In particular, this study aimed to develop practical and shareable lesson materials. The data development procedure was developed according to the following four procedures. 'Development of data development plan, data development, verification of development data, and development of final data that reflects the verification opinions' At this time, in the data development stage, a theme-based design model was applied and developed. In addition, the development data were verified by conducting CVR verification for field teachers to focus on the validity and class applicability, and the final data were presented after the development data being revised to reflect the verification results. This study not only introduced the developed data, but also described the procedure of the data development process and the trial and error and concerns of the developers in the process to provide information on the nature of basic research to other field researchers who attempt data development.