• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.194-196
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• 2011

일반적으로 센서 네트워크에서는 라우팅 트리를 구축한 후에 시간 동기화 작업을 따로 진행하였다. 그 때문에 패킷교환의 횟수가 늘어나고 전력의 소모를 유발한다. 본 논문에서는 라우팅 트리 구축과정에서 교환하는 정방향과 역방향의 패킷에 LTS(Lightweight Time Synchronization) 알고리즘 연산에 필요한 시간정보를 추가하여 플러딩 라우팅 트리 구축 알고리즘과 시간 동기화 과정을 결합한 알고리즘을 제안한다. 또한 일정한 라운드 시간을 사용하여 클럭 휨으로 인한 시간 오류를 보정하였다. 제안하는 알고리즘이 TPSN(Timing-sync Protocol for Sensor Networks) 방식보다 적은 에너지를 사용하고 센서 노드들 간의 시간을 더욱 정교하게 동기화한다는 것을 NS2 시뮬레이터를 통해서 증명하였다.

• Journal of The Korean Association For Science Education
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• v.31 no.6
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• pp.876-886
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• 2011

This study was carried out to investigate the difference of gender of academic self-efficacy, external motivation, interest and science achievement for high school students of Korea and to verify the structural relationship among these variables using PISA 2006 data. The major findings of this study are as follows. According to Multi-group analysis, Latent means analysis (LMA), where boys were used as the reference group, girls showed lower latent mean values on the academic self-efficacy, extrinsic motivation and interest. Academic self-efficacy was found to have a greater effect on achievement compared to external motivation and interest. According to structural equation modeling (SEM) analysis, academic self-efficacy and extrinsic motivation affected interest. Academic selfefficacy, external motivation, and interest affected science achievement. Lastly, interest mediated academic selfefficacy and external motivation on science achievement.

• Journal of The Korean Association For Science Education
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• v.36 no.6
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• pp.835-849
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• 2016

The purpose of the present study is to analyze the trajectory of science core school students' STEM career motivation and to examine the relationship between the trajectory patterns and students' tracks. Longitudinal STEM career motivation data with seven constructs were collected from 256 students for five semesters and the data were analyzed by using group-based trajectory modelling analysis. In order to examine the relationship between trajectory pattern groups and the tracks, chi-square tests were conducted. Based on our findings, we found that students are likely to have similar trajectory patterns in STEM career education experience and in their perception towards STEM career value. In terms of parents' support, academic self-efficacy and STEM career motivation aspects are divided into two distinctive trajectory groups ('high' and 'low' group), while two other variables, STEM career self-efficacy and STEM career interest, are divided into three trajectory groups ('moderate declining', 'high declining', 'increasing' group). Most of the trajectory groups are shown the pattern that the level of each constructs increase until their second academic year, then after that, the patterns started going down. Moreover, there are significant relationship between track and each trajectory groups. Science track and science-core track students have similar trajectory patterns. In contrast, humanities track students have different trajectory groups in some constructs. Based on these findings, we suggest that STEM career education environment should consider various patterns of students' STEM career development.

• Journal of the Korean Society of Earth Science Education
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• v.11 no.2
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• pp.90-106
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• 2018

The purpose of this study is to examine the effect of the backward design reflecting the process-focused assessment on science learning achievement and science learning motivation in elementary science class. The process-focused assessment to support the growth and development of learners and the backward design that seeks a learner's complete understanding can be of great help to science learning. The results of study are as follows. First, we conducted the backward design reflecting the process-focused assessment centering on 'Earth and Moon's movement' unit, and reflecting various process-focused assessment to help achieve achievement standards. Second, as a result of science learning achievement test and science learning motivation test, there were statistically significant differences in the experimental group. It is expected that the process-focused assessment reflecting the characteristics of science subject will be utilized in the school field in conjunction with the backward design.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.397-398
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• 2009

본 논문에서는 증강현실 환경에서 다중 시스템의 물리 시뮬레이션을 위한 동기화 방법을 제안한다. 증강현실 시스템의 몰입감 증대를 위하여 가상 객체에 물리 법칙에 기반을 둔 실질적인 움직임을 부여하는 방법을 논하고 이를 네트워크로 확장하기 위하여 물리 기반 증강현실 환경의 동기화 방법을 연구하였다. 이러한 연구를 통하여 증강현실 어플리케이션의 몰입감 증대와 네트워크 게임에서의 증강현실 도입이라는 새로운 방향도 제시 할 수 있을 것이다.

• The Journal of Natural Sciences
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• v.9 no.1
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• pp.75-81
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• 1997

The method of synchronization by feedbacking a signal of master system to a corresponding variable of slave system is applied to the Lorenz which is autonomous system. The two Lorenz systems are synchronized and the synchronization occurs when the consisting of the variable differences of the two systems generates infinite period of laminar phase. The characteristics of synchronization is analyzed in time series and phase spaces.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.11-11
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• 2003

오늘날 단일 슈퍼컴퓨터로는 처리가 불가능한 거대한 문제들의 해법이 시도되고 있는데, 이들은 지리적으로 분산된 슈퍼컴퓨터, 데이터베이스, 과학장비 및 디스플레이 장치 등을 초고속 통신망으로 연결한 GRID 환경에서 효과적으로 실행시킬 수 있다. GRID는 1990년대 중반 과학 및 공학용 분산 컴퓨팅의 연구 과정에서 등장한 것으로, 점차 응용분야가 넓어지고 있다. 그러나 GRID 같은 분산 환경은 기존의 단일 병렬 시스템과는 많은 점에서 다르며 이전의 기술들을 그대로 적용하기에는 무리가 있다. 기존 병렬 시스템에서는 주로 동기 알고리즘(synchronous algorithm)이 사용되는데, 직렬 연산과 같은 결과를 얻기 위해 동기화(synchronization)가 필요하며, 부하 균형이 필수적이다. 그러나 부하 균형은 이질 클러스터(heterogeneous cluster)처럼 프로세서들의 성능이 서로 다르거나, 지리적으로 분산된 계산자원을 사용하는 GRID 환경에서는 이기종의 문제뿐 아니라 네트워크를 통한 메시지의 전송 지연 등으로 유휴시간이 길어질 수밖에 없다. 이처럼 동기화의 필요성에 의한 연산의 지연을 해결하는 하나의 방안으로 비동기 반복법(asynchronous iteration)이 나왔으며, 지금도 활발히 연구되고 있다. 이는 알고리즘의 동기점을 가능한 한 제거함으로써 빠른 프로세서의 유휴 시간을 줄이는 것이 목적이다. 즉 비동기 알고리즘에서는, 각 프로세서는 다른 프로세서로부터 갱신된 데이터가 올 때까지 기다리지 않고 계속 다음 작업을 수행해 나간다. 따라서 동시에 갱신된 데이터를 교환한 후 다음 단계로 진행하는 동기 알고리즘에 비해, 미처 갱신되지 않은 데이터를 사용하는 경우가 많으므로 전체적으로는 연산량 대비의 수렴 속도는 느릴 수 있다 그러나 각 프로세서는 거의 유휴 시간이 없이 연산을 수행하므로 wall clock time은 동기 알고리즘보다 적게 걸리며, 때로는 50%까지 빠른 결과도 보고되고 있다 그러나 현재까지의 연구는 모두 어떤 수렴조건을 만족하는 선형 시스템의 해법에 국한되어 있으며 비교적 구현하기 쉬운 공유 메모리 시스템에서의 연구만 보고되어 있다. 본 연구에서는 행렬의 주요 고유쌍을 구하는 데 있어 비동기 반복법의 적용 가능성을 타진하기 위해 우선 이론적으로 단순한 멱승법을 사용하여 실험하였고 그 결과 순수한 비동기 반복법은 수렴하기 어렵다는 결론을 얻었다 그리하여 동기 알고리즘에 비동기적 요소를 추가한 혼합 병렬 알고리즘을 제안하고, MPI(Message Passing Interface)를 사용하여 수원대학교의 Hydra cluster에서 구현하였다. 그 결과 특정 노드의 성능이 다른 것에 비해 현저하게 떨어질 때 전체적인 알고리즘의 수렴 속도가 떨어지는 것을 상당히 완화할 수 있음이 밝혀졌다.

• The Journal of the Acoustical Society of Korea
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• v.41 no.2
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• pp.159-165
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• 2022

In this paper, a frame synchronization structure for the Binary Phase Shift Keying (BPSK) modulation method in underwater acoustic communication was proposed. The proposed frame synchronization structure is largely divided into two. First, the approximate position and frequency offset of the frame are obtained by non-coherent correlation and sliding Fast Fourier Transform (FFT) method. Second, after compensating for the frequency error to the received signal, the exact position of the frame is obtained by coherent correlation method. Maritime experiments were conducted to confirm the performance of the 2-STEP frame synchronization structure. It was showed that the limitations of the non-coherent correlation and sliding FFT method can be verified when the power of the received signal was greatly reduced due to the channel characteristics. As a result, stable frame synchronization could be obtained by compensating for the frequency error and then using the coherent correlation method.

• Journal of Science Education
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• v.38 no.3
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• pp.657-669
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• 2014

The purpose of this research is to investigate the effect of students' storytelling on the science learning motivation and science related attitude in elementary science class. We had developed storytelling materials for 11 class hours on the 'Heat transfer and our life' unit based on the analysis of the 4th grade-science curriculum. The research sample was 22 4th graders who were belonged to one of the classes at an elementary school in Gwangju. The test of students' science learning motivation and science related attitude were administered before and after the storytelling treatment, and the difference was checked by the paired t-test using SPSS program. Students' perceptions on the storytelling were also investigated. The conclusions of this research are as follows. First, the students' storytelling tend to have somewhat positive influence on learning motivation. The each mean of post-test in the domain of attention, confidence and satisfaction was significantly higher than that of pre-test. Second, students' storytelling have a positive influence on scientific attitude. Although the means of post-test were higher than those of pre-test in both science subject attitude and scientific attitude domain, a statistically significant difference was found only in the scientific attitude domain. For future researches, the development of more story-materials or strategies for effective storytelling is needed.

• Journal of The Korean Association For Science Education
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• v.26 no.2
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• pp.232-238
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• 2006

This study examined how motivational climate, achievement goals, and learning strategies jointly contributed to science achievement through path analysis of 260 middle school students. The results showed that only deep learning strategy had a significant direct effect on science achievement. The promotion of learning by science teachers and the pursuit of progress by peers had the mediational pathways linking task goal and deep learning strategy on science achievement. The pursuit of progress and the promotion of the comparison by peers influenced science achievement via deep learning strategy. The promotion of the comparison by peers also influenced deep learning strategy via performance-goal, which in turn influenced science achievement. These results indicated that the learning strategies had a direct effect and motivational climate or achievement goals had an indirect effect on science achievement. Our findings lead us to expect that the effective instructional method to improve students' science achievement is the one that impact both cognitive and motivational functioning.