• Journal of KIISE:Information Networking
• /
• v.32 no.6
• /
• pp.668-675
• /
• 2005

With the proliferation of wireless network and the advances of the embedded systems, the traditional distributed systems begin to include the wireless embedded systems. Clock synchronization in the distributed systems is one of the major issues that should be considered for diverse Purposes including synchronization, ordering, and consistency. Many clock synchronization algorithms have been proposed over the years. Since clock synchronization in wireless embedded systems should consider the low bandwidth of a network and the poor resources of a system, most traditional algorithms cannot be applied directly. We propose a clock synchronization algorithm in wireless embedded systems, extending IEEE 802.11 standard. The proposed algorithm can not only achieve high precision by loosening constraints and utilizing the characteristics of wireless broadcast but also provide continuous time synchronization by tolerating the message losses. In master/slave structure the master broadcasts the time information and the stave computes the clock skew and the drift to estimate the synchronized time of the master. The experiment results show that the achieved standard deviation by the Proposed scheme is within the bound of about 200 microseconds.

• Journal of Industrial Convergence
• /
• v.20 no.6
• /
• pp.47-54
• /
• 2022

The purpose of this study was to identify the effects of the health leader education on health behavior motivation, perceived health status, knowledge improvement, and life satisfaction among the living in rural area. The subjects consisted of 50 health leaders who participated in the health leader education program. Pre-and post-education tests were collected after education. The data were analyzed using the SPSS 22.0 program with frequency, means, ANOVA, Paired t-test. The data significant changes in motivation, perceived health status, knowledge improvement. The data not significant changes in life satisfaction. Based on this study, a continuous health leader education program through a community health center is needed for rural community people.

• Journal of the Korean Applied Science and Technology
• /
• v.40 no.5
• /
• pp.1001-1009
• /
• 2023

Flow is a concept closely related to intrinsic motivation and is considered a positive factor in sports performance in sports psychology. The purpose of this study was to confirm the addictive nature of Flow through previous studies and propose a new hypothesis that Flow may decrease intrinsic motivation in the long term, unlike previous studies. In line with adaptation level theory and the law of diminishing marginal utility, the satisfaction derived from Flow is continuously decreasing. At some point, the individual's progress is limited and they reach a point where they no longer experience FLOW. However, the individual will continue to try because the desire to experience FLOW again exists. However, failure to experience FLOW and repeated failure will lead to sadness, which will decrease intrinsic motivation.

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.07a
• /
• pp.234-235
• /
• 2002

최근 상호 결합된 chaotic 진동자들 간의 동기화의 문제는 그 시스템이 가지는 여러 가지 응용성 때문에 여러 과학 분야와 기술 분야 예를 들면 동력학, 레이져 동력학, 전자회로, 화학반응, 생물학적인 시스템 등에서 폭넓게 연구되어지고 있다. 더욱이 작은 파라미터의 차이를 제외하고 거의 유사한 chaotic 진동자들간의 상호작용에서 찾아 볼 수 있는 위상 동기화 현상은 뇌세포 조직과 같은 생물학적인 시스템들 사이에 흔히 찾아 볼 수 있는 기본적인 현상이다. (중략)

• Journal of The Korean Association For Science Education
• /
• v.44 no.2
• /
• pp.141-153
• /
• 2024

The 2022 revised science curriculum aims to develop the ability to solve scientific problems arising in daily life and society based on convergent thinking stimulated through participation in research activities using artificial intelligence (AI). Therefore, we developed a science-AI convergence education program that combines the science curriculum with artificial intelligence and employed it in convergence classes for high school students. The aim of the science-AI convergence class was for students to qualitatively understand the movement of a damped pendulum and build an AI model to predict the position of the pendulum using the block coding platform KNIME. Individual in-depth interviews were conducted to understand and interpret the learners' experiences. Based on Giorgi's phenomenological research methodology, we described the learners' learning processes and changes, challenges and limitations of the class. The students collected data and built the AI model. They expected to be able to predict the surrounding phenomena based on their experimental results and perceived the convergence class positively. On the other hand, they still perceived an with the unfamiliarity of platform, difficulty in understanding the principle of AI, and limitations of the teaching method that they had to follow, as well as limitations of the course content. Based on this, we discussed the strengths and limitations of the science-AI convergence class and made suggestions for science-AI convergence education. This study is expected to provide implications for developing science-AI convergence curricula and implementing them in the field.

• Bulletin of the Korean Space Science Society
• /
• 2010.04a
• /
• pp.31.2-31.2
• /
• 2010

편대비행 위성이 공동의 임무를 수행하기 위해서는 편대를 이루는 위성의 각기 다른 초기 오차와 다양한 외란 환경에서도 자세 동기화를 이룰 수 있는 기법이 필요하다. 이 연구에서는 편대비행위성의 자세 동기화를 위하여 비선형 시스템에 대한 준최적 제어기법인 SDRE(State-Dependent Riccati Equation)에 기반한 추적 제어기가 사용되었다. 반작용 휠이 포함된 위성의 자세 동역학이 SDRE 추적 제어기를 구성하는데 이용된다. 이를 Leader/Follower 편대비행 시스템에 적용하며, 기준 자세를 추적하는 Leader 위성의 자세를 Follower 위성이 추적하여 자세 동기화를 이룰 수 있다. MATLAB과 SIMULINK를 이용한 수치해석적 시뮬레이션으로 추적 제어기의 성능을 검증하였으며, 이에 대한 실시간 HIL(Hardware-In-the-Loop) 시뮬레이션이 수행되었다. 무중력 환경을 모사하는 에어베어링시스템과 세 개의 반작용 휠을 장착한 자세제어 HILS(Hardware-In-the-Loop Simulator)는 PC104 타입의 임베디드 컴퓨터에서 SIMULINK의 xPC Target을 이용한 실시간 시뮬레이션 환경을 제공하며, 이에 적용되는 SDRE 추적 제어기는 이산화되어 설계되었다. 또한 SDRE 추적 제어기에 대한 안정성을 보장하는 영역이 추정되어 위 추적 제어기가 위성 편대비행에 적합한 자세 동기화 기법임을 보였다.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.3
• /
• pp.331-335
• /
• 2010

Previous low-energy time synchronization methods have mainly focused on reducing the number of transmission or reception packets. However, this paper proposes a method that reduces the percentage of time a node has to be awake (the duty cycle), assuming that a periodic sleep-wake cycle is used to conserve energy. Based on our experience with actual WSN devices, a system model is proposed, and the potential performance of the proposed method, with different parameter values, is analyzed. To further demonstrate the feasibility of our method, experiments were conducted using nine WSN devices in a $3{\times}3$ grid network topology. The results show the average synchronization error is 107.57 $\mu{s}$ in duty cycle 5% and synchronization period 10 sec, and 130 $\mu{s}$ in duty cycle 2.5% and synchronization period 20 sec.

• Journal of The Korean Association For Science Education
• /
• v.22 no.4
• /
• pp.757-767
• /
• 2002

This study investigated the effects of scientific inquiry experiments emphasizing social interaction on the academic achievement, the ability for science inquiry and the learning motivation of the students. To examine the differences among the classes of scientific inquiry experiments according to the way of organizing small groups, the effects of the group in homogeneous cognitive level and the group in heterogeneous cognitive level were compared. 255 7th-graders were grouped into the treatment group and the control group. After the treatment group received the scientific inquiry experimental lessons emphasizing social interaction and the control group received traditional lessons for one year, academic achievement, ability for scientific inquiry, and learning motivation were examined. These inquiry experiments were composed of four steps which are eliciting, familiarizing, constructing and bridging. And students can interact with peers and teachers through the process of relating observed phenomena to concept, constructing experiment procedure, and eliciting results. The ANCOVA results revealed that there were significant effects of science inquiry experiments emphasizing social interaction on the academic achievement, the ability for scientific inquiry and the learning motivation of the students. The significant academic achievement of the students in most of the cognitive levels, if not all, was found and degree of improvement in the ability for scientific inquiry was lower than that in the academic achievement. Concerning the effects according to the way of organizing small groups, there were significant improvement in academic achievement and learning motivation of the group in homogeneous cognitive level compared to the group in heterogeneous cognitive level. These results indicate that social interaction in learning is important and it has positive influences on the improvement in academic achievement and ability for scientific inquiry of students.

• Journal of The Korean Association For Science Education
• /
• v.25 no.4
• /
• pp.465-471
• /
• 2005

In this study, the effects of reciprocal peer tutoring strategy on science achievement, science learning motivation, and self-esteem were investigated. Three classes of eighth graders (N=94) at a coed middle school were sampled for the study. They were divided into the comparison group, the cooperative learning (CL) group, and the reciprocal peer tutoring (RPT) group. Students were taught about the separation of mixtures for 13 class hours. Mid-term science examination scores were used as a blocking variable. The two-way ANCOVA results revealed that there were no significant differences among the three groups in the science achievement test, although the scores of the RPT group were higher than those of the comparison group. In all the subtests of the science learning motivation questionnaire, the scores of the RPT group were significantly higher than those of the comparison group. The scores of the RPT group were significantly higher than those of the other groups especially in the confidence part of the science learning motivation questionnaire. In the self-esteem test, the low achievers in the RPT group scored significantly higher than those in the CL group.

• Journal of The Korean Association of Information Education
• /
• v.20 no.1
• /
• pp.57-68
• /
• 2016

The purpose of this study is to examine factors affecting flipped learning outcomes. For this study, 44 middle school students participated in flipped learning activities during science classes. After 5 week of classes, they responded the following surveys: intrinsic motivation, self-regulation, interest in class, interest in science, and learning achievement. Multiple regression analyses with correlation applied to this study as data analysis methods. The results showed that intrinsic motivation significantly predicted interest in class and interest in science. In addition, self-regulation significantly predicted learning achievement. Therefore, these findings imply that intrinsic motivation and self-regulation should be considered for designing flipped learning activities in middle school science classes.