• School Mathematics
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• v.19 no.4
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• pp.691-712
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• 2017

It is an important to develop teachers' statistical reasoning or thinking by teacher education. In this study, the "comparing two data sets" tasks is focused as a way to develop pre-service elementary teachers' reasoning about core ideas of statistics such as distribution, variability, center, and spread. 6 teams of each 4 pre-service elementary teachers participated on the tasks and their presentations are analyzed based on Pfannkuch's (2006) teachers' inference model in comparing two data sets. As a result, they paid attention to the distribution and variability in the statistical problem solving by the "comparing two data sets" tasks, and used their contextual knowledge to make a statistical decision. In addition, they used some statistics and graphs as the reference for statistical communication, which is expected to provide implications for improving statistical education. The finding implies that the "comparing two data sets" tasks can be used to develop statistical reasoning of pre-service elementary teachers. Some recommendations are suggested for teacher education by these tasks.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.3
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• pp.227-237
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• 2022

The most critical factors for detecting changes in very high-resolution satellite images are building positional inconsistencies and relief displacements caused by satellite side-view. To resolve the above problems, additional processing using a digital elevation model and deep learning approach have been proposed. Unfortunately, these approaches are not sufficiently effective in solving these problems. This study proposed a change detection method that considers both positional and topology information of buildings. Mask R-CNN (Region-based Convolutional Neural Network) was trained on a SpaceNet building detection v2 dataset, and the central points of each building were extracted as building nodes. Then, triangulated irregular network graphs were created on building nodes from temporal images. To extract the area, where there is a structural difference between two graphs, a change index reflecting the similarity of the graphs and differences in the location of building nodes was proposed. Finally, newly changed or deleted buildings were detected by comparing the two graphs. Three pairs of test sites were selected to evaluate the proposed method's effectiveness, and the results showed that changed buildings were detected in the case of side-view satellite images with building positional inconsistencies.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.419-422
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• 2004

In this paper, we propose a new metric called "dynamic gamma" to quantitatively evaluate the dynamic temporal response of an LC display device. The widely-used response time and corresponding 3-D bar graphs cannot fully describe the dynamic characteristics of an LC panel [1], and using response time to compare different LC panels and assessing the dynamic features of LC panels is difficult. On the other hand, the new metric MPRT mixes an LC panel's slow temporal response with its hold-type display effect. The proposed new metric, dynamic gamma, and corresponding 2-D plots, are arguably more suitable for quantitatively characterizing the dynamic characteristics of an LC panel, so comparing two LC panels becomes easy. Furthermore, dynamic gamma has the unique property that it can be used to quantify the limitations/capabilities and to assess the effectiveness of an overdrive mechanism for a particular LCD. In the paper, two LC panels using different technology are analyzed and compared using this new metric.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.717-728
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• 2011

An efficient method for the unsupervised classification of high resolution imagery is suggested in this paper. It employs pixel-linking and merging based on the adjacency graph. The proposed algorithm uses the neighbor lines of 8 directions to include information in spatial proximity. Two approaches are suggested to employ neighbor lines in the linking. One is to compute the dissimilarity measure for the pixel-linking using information from the best lines with the smallest non. The other is to select the best directions for the dissimilarity measure by comparing the non-homogeneity of each line in the same direction of two adjacent pixels. The resultant partition of pixel-linking is segmented and classified by the merging based on the regional and spectral adjacency graphs. This study performed extensive experiments using simulation data and a real high resolution data of IKONOS. The experimental results show that the new approach proposed in this study is quite effective to provide segments of high quality for object-based analysis and proper land-cover map for high resolution imagery of urban area.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.182-187
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• 2017

Synchronous generators have been significantly applied in large-scale power plants and its monitoring systems are additionally established to sequentially observe states and outputs. We develop a computer based monitoring device for three-phase synchronous power generators in this paper. First, a test-bed of such generator system is created and then a interface board is constructed to transfer electric signals including the output voltage and the current from generators into a computer system via a data acquisition device. Its RMS(root-mean-square) values are continuously shown on a screen of computer systems and its time-histories graphs are additionally illustrated under a graphic user interface(GUI) mode. Lastly, we carry out real-time experiments using the generator system with the monitoring device to demonstrate its reliability and superiority by comparing results of a generic power analyzer which is well-used in measuring various power systems practically.

• International Journal of Contents
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• v.10 no.1
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• pp.23-28
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• 2014

When developing a classifier using various objective functions, it is important to compare the performances of the classifiers. Although there are statistical analyses of objective functions for classifiers, simulation results can provide us with direct comparison results and in this case, a comparison criterion is considerably critical. A Receiver Operating Characteristics (ROC) graph is a simulation technique for comparing classifiers and selecting a better one based on a performance. In this paper, we adopt the ROC graph to compare classifiers trained by mean-squared error, cross-entropy error, classification figure of merit, and the n-th order extension of cross-entropy error functions. After the training of feed-forward neural networks using the CEDAR database, the ROC graphs are plotted to help us identify which objective function is better.

• Steel and Composite Structures
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• v.22 no.2
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• pp.411-427
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• 2016

In this study, by using finite element non-linear static analysis and comparing it with experimental models, the buckling and post-buckling behavior of bracing gusset plates has been investigated. The effects of such parameters as dimension and thickness of the gusset plate and the influence of position of the bracing member on the behavior of gusset plate have been examined. The results of the analyses clearly suggest that capacity, buckling and post-buckling behaviors of gusset plates depend on the position of the bracing splice plate with respect to the free bending line as well as on the size and thickness of the gusset plate. Also, with respect to numerical analysis results, some practical graphs for the calculation of buckling capacity of gusset plate connections are presented. For steel structures, the proposed method is apparently more accurate than available code procedures.

• Journal of the Korean Society of Systems Engineering
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• v.10 no.1
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• pp.57-64
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• 2014

We propose a methodology to automatically extract the requirements from the documents and check the traceability between them. The documents include not only the text file but also PDF or image files. We also suggest a method to visualize the result with maps, numbers, and graphs. By comparing the results with those of expert reviews, we show that it is necessary to use knowledge-based method in future instead of the word-based method for improving the reliability. The results give more values when they are applied in already existing documents than those of newly developed product.

• Journal of the Korea Society for Simulation
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• v.3 no.1
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• pp.125-134
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• 1994

In real-time database systems, transactions's commitment done before the given deadlines is more important than just getting the maximum throughput. Transactions missing the given deadlines are no longer meaningful in real-time applications. Therefore, there is a need for new transaction processing models to meet the given deadlines in real-time database applications, because moat conventional transaction models are not designed to meet deadlines. In this paper we propose a new transaction models which uses multiple versions of a data item. The model uses read-from graphs and dynamic reorder of transactions to meet deadlines. A read-from graph contains the past read semantics of read operations and support the model to decide which database operation to be taken. Then, we show simulation results comparing the proposed model with other transaction models such as two phase locking model and the optimistic concurrency control model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.22-25
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• 2003

It is usually difficult for a single user to have all the essential knowledge on various Rapid Prototyping processes and techniques. It is therefore necessary to capture knowledge and experience of users of expert level into a decision-support system which provides quicker and more interactive way to select proper RP process and/or machine. rather than reading reports on benchmarking studies and comparing tables and graphs. In this paper two algorithms are presented, which may be used in such a decision-support system. together with its applications. The one is an extended PRES(Project Evaluation and Selection) algorithm which applies weighting factors of each attribute. The other is a LCE(Linear Confidence Equation) algorithm which is proposed to apply user's input requirements as well as weighting factors.