• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.339-346
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• 2012

The pre-evaluation of the current-collection performance is an important issue for high-speed railway vehicles. In this paper, using flexible multibody dynamic analysis techniques, a simulation model of the dynamic interaction between the catenary and pantograph is developed. In the analysis model, the pantograph is modeled as a rigid body, and the catenary wire is developed using the absolute nodal coordinate formulation, which can analyze large deformable parts effectively. Moreover, for the representation of the dynamic interaction between these parts, their relative motions are constrained by a sliding joint. Using this analysis model, the contact force and loss of contact can be calculated for a given vehicle speed. The results are evaluated by EN 50318, which is the international standard with regard to analysis model validation. This analysis model may contribute to the evaluation of high-speed railway vehicles that are under development.

• Journal of The Korean Association For Science Education
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• v.27 no.4
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• pp.285-296
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• 2007

Graph is a major aspect of science textbooks. In this study, we investigated graph types and characteristics used in high school earth science subject by comparative analysis of science textbooks. The results of the analysis revealed that line graph and contour map was the most widely used graph types in earth science. Among line graphs, multiple line graph and YX graph was dominant. Comparing earth science graphs with other science graphs, earth science graphs exhibited superior in the number and variety. In earth science graphs, the portion of line graph was small, but the portion of contour map and scatter graph was larger than that of other science graphs. YX graph was the most specific graph type in earth science textbooks. The results of our study have implications for reform in function and structure of graph. We suggest that future studies be focused on students' ability of earth science graph interpretation.

• School Mathematics
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• v.18 no.3
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• pp.457-478
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• 2016

The purpose of this study is to investigate middle school students' understanding and development of function graphs. We collected the data from the teaching experiment with two middle school students who had not yet received instruction on linear function in school. The students participated in a 15-day teaching experiment(Steffe, & Thompson, 2000). Each teaching episode lasted one or two hours. The students initially focused on numerical values rather than the overall relationship between the variables in functional situations. This study described meaning, role of and students' responses for the given tasks, which revealed the students' understanding and development of function graphs. Especially we analyzed students' responses based on their methods to solve the tasks, reasoning that derived from those methods, and their solutions. The results indicate that their continuous reasoning played a significant role in their understanding of function graphs.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.1
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• pp.169-192
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• 2019

This study investigates how well grade 4, 5, and 6 students understand graphs before formal education is done on graphs. For this, we analyzed students' understanding of graphs by classifying them into 'reading data', 'finding relationships between data', 'interpreting data', and 'understanding situations' based on previous studies. The results show that the students have good understanding of graphs that did not have formal education. This suggests that it is necessary to consider the timing of the introduction of the graph. In addition, when we look at the percentage of correctness of each graph, it is found that the understanding of the line graph is weaker than the other graphs. The common error in most graphs was that students relied on their own subjective thoughts and experiences rather than based on the data presented.

• Journal of The Korean Association For Science Education
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• v.25 no.2
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• pp.122-132
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• 2005

Graphing abilities are critical to understand and convey information in science. And then, to what extent are secondary students in science courses able to understand line graphs? To find clues about the students' interpretation processes of the information in science-related line graphs, this study has the following research question: Is there a difference between the levels of complexity of good and poor readers as they use the thinking aloud method for studying cognitive processes? The present study was designed to provide evidence for the hypothesis that good line graph readers use a specific graph interpretation process when reading and interpreting line graphs. With the aid of the thinking aloud method we gained deeper insight into the interpretation processes of good and poor graph readers while verifying verbal statements with respect to line graphs. The high performing students tend to read much more information and more trend-related information than the low performing students. We support the assumption of differential line graph schema existing in the high performing students in conjunction with general graph schema. Also, high performing students tend to think aloud much more metacognitively than low performing students. High performing students think aloud a larger quantity of information from line graphs than low performing students, and more trend-related sentences than value-related sentences from line graphs. The differences of interpretation processes revealed between good and poor graph readers while reading and interpreting line graphs have implications for instructional practice as well as for test development and validation. Teaching students to read and interpret graphs flexibly and skillfully is a particular challenge to anyone seriously concerned with good education for students who live in an technological society.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.417-419
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• 2000

본 논문은 실시간 운영체제 기반의 ITV 시스템에서 MPEG-4 멀티미디어 장면을 실시간으로 랜더링하는 방법을 제시한다. MPEG-4 멀티미디어 스트림의 랜더링을 위한 장면 구성은 ITV 시스템에서 네트워크를 통해 전송되는 멀티미디어 스트림을 파싱 및 해석하여 장면그래프를 구성하고, 장면 랜더러가 이 장면 그래프를 이용하여 화면에 실시간으로 랜더링한다. MPEG-4 장면 랜더링 화면에서 사용자의 객체 교체나 객체 속성 변환 랜더링 이벤트가 발생하면, MPEG-4 장면 그래프를 실시간으로 갱신시켜 사용자 인터페이스에 랜더링한다.

• 전기의세계
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• v.28 no.4
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• pp.25-31
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• 1979

• Annual Conference on Human and Language Technology
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• 2022.10a
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• pp.219-224
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• 2022

최근 딥러닝이 상식 정보를 추론하지 못하거나, 해석 불가능하다는 한계점을 보완하기 위해 지식 그래프를 기반으로 자연어 텍스트를 생성하는 연구가 중요하게 수행되고 있다. 그러나 이를 위해서 대량의 지식 그래프와 이에 대응되는 문장쌍이 요구되는데, 이를 구축하는 데는 시간과 비용이 많이 소요되는 한계점이 존재한다. 또한 하나의 그래프에 다수의 문장을 생성할 수 있기에 구축자 별로 품질 차이가 발생하게 되고, 데이터 균등성에 문제가 발생하게 된다. 이에 본 논문은 공개된 지식 그래프인 디비피디아를 활용하여 전문가의 도움 없이 자동으로 데이터를 쉽고 빠르게 구축하는 방법론을 제안한다. 이를 기반으로 KoBART와 mBART, mT5와 같은 한국어를 포함한 대용량 언어모델을 활용하여 문장 생성 실험을 진행하였다. 실험 결과 mBART를 활용하여 미세 조정 학습을 진행한 모델이 좋은 성능을 보였고, 자연스러운 문장을 생성하는데 효과적임을 확인하였다.

• Communications for Statistical Applications and Methods
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• v.15 no.1
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• pp.65-76
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• 2008

Biplots are the multivariate analogue of scatter plots. They approximate the multivariate distribution of a sample in a few dimensions, typically two, and they superimpose on this display representations of the variables on which the samples are measured(Gower and Hand, 1996, Chapter 1). And the relationships between the observations and variables can be easily seen. Thus, biplots are useful for giving a graphical description of the data. However, this method does not give some concise interpretations between variables and observations when the number of observations are large. Therefore, in this study, we will suggest to interpret the biplot analysis by applying the K-means clustering analysis. It shows that the relationships between the clusters and variables can be easily interpreted. So, this method is more useful for giving a graphical description of the data than using raw data.

• The Journal of Korean Association of Computer Education
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• v.17 no.6
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• pp.103-113
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• 2014

This study designed and implemented a query model for consecutive analyses of dynamic multivariate graph data. First, the query model consists of two procedures; setting the discriminant function, and determining an alteration method. Second, the query model was implemented as a query system that consists of a query panel, a graph visualization panel, and a property panel. A Node-Link Diagram and the Force-Directed Graph Drawing algorithm were used for the visualization of the graph. The results of the queries are visually presented through the graph visualization panel. Finally, this study used the data of worldwide import & export data of small arms to verify our model. The significance of this research is in the fact that, through the model which is able to conduct consecutive analyses on dynamic graph data, it helps overcome the limitations of previous models which can only perform discrete analysis on dynamic data. This research is expected to contribute to future studies such as online decision making and complex network analysis, that use dynamic graph models.