• 한국지능시스템학회논문지
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• 제21권4호
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• pp.493-498
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• 2011

본 논문은 측정값의 우도를 기준으로 선택적인 측정값 적용을 통한 향상된 GraphSLAM을 제안하였다. GraphSLAM은 로봇의 이동 경로와 환경에 대한 지도를 전체 입력 데이터를 통해 추정한다. 그러나 잡음이 강한 환경에서 센서의 측정치가 부정확한 경우가 늘어나면, 전체 입력 데이터를 사용하는 GraphSLAM의 경우 정확성이 크게 떨어지게 된다. 그러므로 본 논문에서는 들어오는 센서의 측정값들을 선별하여 GraphSLAM에 적용하는 방법을 제안한다. 이 방법을 통해 잡음이 강한 환경에서 기존의 GraphSLAM보다 향상된 성능을 제공할 수 있다.

• Journal of Information Processing Systems
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• 제19권6호
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• pp.803-816
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• 2023

Explainable artificial intelligence is a method that explains how a complex model (e.g., a deep neural network) yields its output from a given input. Recently, graph-type data have been widely used in various fields, and diverse graph neural networks (GNNs) have been developed for graph-type data. However, methods to explain the behavior of GNNs have not been studied much, and only a limited understanding of GNNs is currently available. Therefore, in this paper, we propose an explanation method for node classification using graph convolutional networks (GCNs), which is a representative type of GNN. The proposed method finds out which features of each node have the greatest influence on the classification of that node using GCN. The proposed method identifies influential features by backtracking the layers of the GCN from the output layer to the input layer using the gradients. The experimental results on both synthetic and real datasets demonstrate that the proposed explanation method accurately identifies the features of each node that have the greatest influence on its classification.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.333-351
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• 2002

This paper introduces a search method based on conceptual graph. A hyperlink information is essential to construct conceptual graph in web. The information is very useful as it provides summary and further linkage to construct conceptual graph that has been provided by human. It also has a property which shows review, relation, hierarchy, generality, and visibility. Using this property, we extracted the keywords of web documents and made up of the conceptual graph among the keywords sampled from web pages. This paper extracts the keywords of web pages using anchor text one out of hyperlink information and makes hyperlink of web pages abstract as the link relation between keywords of each web page. 1 suggest this useful search method providing querying word extension or domain knowledge by conceptual graph of keywords. Domain knowledge was conceptualized knowledged as the conceptual graph. Then it is not listing web documents which is the defect of previous search system. And it gives the index of concept associating with querying word.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제25권1호
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• pp.23-34
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• 1997

Seismic tomography using the graph theoretical method of ray tracing is performed in two synthetic data sets with laterally varying velocity structures. The straight-ray tomography shows so poor results in imaging the laterally varying velocity structure that the ray-traced tomographic techniques should be used. Conventional ray tracing methods have serious drawbacks, i.e. problems of convergence and local minima, when they are applied to seismic tomography. The graph theretical method finds good approximated raypaths in rapidly varying media even in shadow zones, where shooting methods meet with convergence problems. The graph theoretical method ensures the globally minimal traveltime raypath while bending methods often cause local minima problems. Especially, the graph theoretical method is efficient in case that many sources and receivers exist, since it can find the traveltimes and corresponding raypaths to all receivers from a specific source at one time. Moreover, the algorithm of graph theoretical method is easily applicable to the ray tracing in anisotropic media, and even to the three dimensional case. Among the row-active inversion techniques, the conjugate gradient (CG) method is used because of fast convergence and high efficiency. The iterative sequence of the ray tracing by the graph theoretical method and the inversion by the CG method is an efficient and robust algorithm for seismic tomography in laterally varying velocity structures.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권1호
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• pp.147-169
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• 2024

In pace with the development of network technology at lightning speed, social networks have been extensively applied in our lives. However, as social networks retain a large number of users' sensitive information, the openness of this information makes social networks vulnerable to attacks by malicious attackers. To preserve the link privacy of individuals in social networks, an uncertain graph method based on node random response is devised, which satisfies differential privacy while maintaining expected data utility. In this method, to achieve privacy preserving, the random response is applied on nodes to achieve edge modification on an original graph and node differential privacy is introduced to inject uncertainty on the edges. Simultaneously, to keep data utility, a divide and conquer strategy is adopted to decompose the original graph into many sub-graphs and each sub-graph is dealt with separately. In particular, only some larger sub-graphs selected by the exponent mechanism are modified, which further reduces the perturbation to the original graph. The presented method is proven to satisfy differential privacy. The performances of experiments demonstrate that this uncertain graph method can effectively provide a strict privacy guarantee and maintain data utility.

• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.37-45
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• 2002

We described a method of resonant mode identification in dielectric-disc loaded cylindrical cavity resonators. The characteristic equations are solved using the ContourPlot graph of Mathematica. Contour graph method uses graphical method. It is comparable with numerical method. The numerical method is very difficult mode identification. The analysis is based on the approximated electromagnetic representation which is only concentrated on the calculation of resonant frequencies, and a mode identification of resonant frequencies has not been covered. However, It is possible to calculate precise resonant frequencies and to identify the mode of resonant frequencies using the contour graph method. The contour graph method is not a method using approximated representation of electromagnetic field variation at the outer area of dielectric in the resonators. It is a method using enact representation.

• 터널과지하공간
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• 제15권5호
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• pp.369-377
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• 2005

지하공동의 안정성은 생산성과 안전을 확보해야 하는 광산의 운영에 있어서 가장 중요한 관심사이다. 암반분류는 많은 경험적인 설계방법의 근간을 이룰 뿐만 아니라 수치해석을 위한 기초자료로 이용되고 있다. 공동의 안정성에 영향을 주는 많은 요소들 중 주어진 암반의 조건 중에서 공동폭은 하나의 중요한 설계요소가 된다. 이 논문에서는 Lug에 의해 제안된 한계 공동폭 기준, Mathews stability graph method 그리고 저자들에 의해 제안된 한계 공동폭 기준을 비교하였다. Methews stability graph method를 이용하여 저자들에 의해 수정된 한계 공동폭 기준을 제안하였고 이것을 여러 석회석 광산 지하공동의 안정성을 평가하는 데 사용하였다.

• Journal of Platform Technology
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• 제9권4호
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• pp.3-9
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• 2021

이 논문에서는 차량 또는 도로 인프라 센서에 의해 검출된 도로상의 각 객체들 간의 상황인지를 효과적으로 하기 위해서 그래프 데이터 모델을 도입한다. 제안하는 방법은 도로상의 각 객체들을 그래프의 정점(Vertex)로, 객체들 간의 관계를 그래프의 간선(Edge)로 모델링하여 그래프 데이터베이스를 구축하고, 객체의 속성과 간선의 속성을 실시간으로 업데이트한다. 이때 간선으로 표현되는 객체들 간의 관계는 각 객체의 위치, 이동방향, 이동속도 등을 고려하여 객체들 간에 근접 가능성이 있을 경우 설정한다. 또한, 제안하는 그래프 모델링 방법을 통해 표현한 도로 객체 그래프 데이터베이스를 실시간으로 업데이트하기 위해 그래프 정점과 간선에 대한 공간 색인 기법을 제안한다. 제안하는 색인기법 기반의 그래프 데이터베이스 업데이트 성능을 평가하기 위해서 색인 없이 업데이트하는 방법과 비교하였으며 비교결과 제안하는 방법이 10배 더 빠르게 업데이트를 할 수 있음을 확인하였다.

• 대한의용생체공학회:의공학회지
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• 제38권2호
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• pp.82-88
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• 2017

Enlargement of the lateral ventricles have been identified as a surrogate marker of neurological disorders. Quantitative measure of the lateral ventricle from MRI would enable earlier and more accurate clinical diagnosis in monitoring disease progression. Even though it requires an automated or semi-automated segmentation method for objective quantification, it is difficult to define lateral ventricles due to insufficient contrast and brightness of structural imaging. In this study, we proposed a fully automated lateral ventricle segmentation method based on a graph cuts algorithm combined with atlas-based segmentation and connected component labeling. Initially, initial seeds for graph cuts were defined by atlas-based segmentation (ATS). They were adjusted by partial volume images in order to provide accurate a priori information on graph cuts. A graph cuts algorithm is to finds a global minimum of energy with minimum cut/maximum flow algorithm function on graph. In addition, connected component labeling used to remove false ventricle regions. The proposed method was validated with the well-known tools using the dice similarity index, recall and precision values. The proposed method was significantly higher dice similarity index ($0.860{\pm}0.036$, p < 0.001) and recall ($0.833{\pm}0.037$, p < 0.001) compared with other tools. Therefore, the proposed method yielded a robust and reliable segmentation result.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.791-794
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• 2001

We described a method resonant mode identification in dielectric-disc loaded cylindrical cavity resonators. The characteristic equation is solved by using the ContourPlot graph of Mathematica. Contour graph method uses graphical method. It is comparable with numerical method. The numerical method is very difficult a mode identification. The analysis based on the approximated electromagnetic representation. This kinds of studies only concentrated on the calculation of resonant frequencies, and a mode identification of resonant frequencies have not been covered. But, the contour graph method to analyze the characteristic equations is simple and all parts of resonant frequency graph can be easily drawn, it is possible to calculate precise resonant frequencies and to identify the mode of resonant frequencies.