• 호남수학학술지
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• 제30권4호
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• pp.589-602
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• 2008

As a survey-type article, the paper reviews various digital topological utilities from digital covering theory. Digital covering theory has strongly contributed to the calculation of the digital k-fundamental group of both a digital space(a set with k-adjacency or digital k-graph) and a digital product. Furthermore, it has been used in classifying digital spaces, establishing almost Van Kampen theory which is the digital version of van Kampen theorem in algebrate topology, developing the generalized universal covering property, and so forth. Finally, we remark on the digital k-surface structure of a Cartesian product of two simple closed $k_i$-curves in ${\mathbf{Z}}^n$, $i{\in}{1,2}$.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권1호
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• pp.364-380
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• 2016

The most popular approach in object classification is based on the bag of visual-words model, which has several fundamental problems that restricting the performance of this method, such as low time efficiency, the synonym and polysemy of visual words, and the lack of spatial information between visual words. In view of this, an object classification based on weakly supervised E2LSH and saliency map weighting is proposed. Firstly, E2LSH (Exact Euclidean Locality Sensitive Hashing) is employed to generate a group of weakly randomized visual dictionary by clustering SIFT features of the training dataset, and the selecting process of hash functions is effectively supervised inspired by the random forest ideas to reduce the randomcity of E2LSH. Secondly, graph-based visual saliency (GBVS) algorithm is applied to detect the saliency map of different images and weight the visual words according to the saliency prior. Finally, saliency map weighted visual language model is carried out to accomplish object classification. Experimental results datasets of Pascal 2007 and Caltech-256 indicate that the distinguishability of objects is effectively improved and our method is superior to the state-of-the-art object classification methods.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.213-217
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• 2004

This paper presents a method of constructing the digital logic systems(DLS) using edge-valued decision diagrams(EVDD). The proposed method is as following. The EVDD is a new data structure type of decision diagram(DD) that is recently used in constructing the digital logic systems based on the graph theory. Next, we apply EVDD to function minimization of digital logic systems. The proposed method has the visible, schematical and regular properties.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.524-529
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• 2002

In this paper, we report the development of two DEM (digital elevation model) generation algorithms over urban areas from an IKONOS stereo pair. One ("EpiMatch") is originally developed for SPOT images and modified for IKONOS images. It uses epipolar geometry for accurate DEM generation. The other is based on graph-cut algorithm in 3D voxel space. This algorithm is believed to work better on height discontinuities than EpiMatch. An IKONOS image pair over Taejon city area was used for tests. Using ground control points obtained from differential GPS, camera model was set up and stereo matching applied. As a result, two DEMs over urban areas were produced. Within a DEM from EpiMatch small houses appear as small "cloudy" patches and large apartment and industrial buildings are visually identifiable. Within the DEM from graph-cut we could achieve better height information on building boundaries. The results show that both algorithms can generate DEMs from IKONOS images although more research is required on handling height discontinuities (for "EpiMatch") and on faster computation (for "Graph-cut").

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (A)
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• pp.281-282
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• 2008

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권9호
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• pp.4788-4813
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• 2019

In this paper, we introduce concepts of optimal and near optimal secret data hiding schemes. We present a new digital image steganography approach based on the Galois field $GF(p^m)$ using graph and automata to design the data hiding scheme of the general form ($k,N,{\lfloor}{\log}_2p^{mn}{\rfloor}$) for binary, gray and palette images with the given assumptions, where k, m, n, N are positive integers and p is prime, show the sufficient conditions for the existence and prove the existence of some optimal and near optimal secret data hiding schemes. These results are derived from the concept of the maximal secret data ratio of embedded bits, the module approach and the fastest optimal parity assignment method proposed by Huy et al. in 2011 and 2013. An application of the schemes to the process of hiding a finite sequence of secret data in an image is also considered. Security analyses and experimental results confirm that our approach can create steganographic schemes which achieve high efficiency in embedding capacity, visual quality, speed as well as security, which are key properties of steganography.

• 디지털융복합연구
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• 제12권3호
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• pp.353-358
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• 2014

급성기 허혈성 뇌졸중 증상이 있는 뇌 관류 CT 검사를 시행한 환자를 대상으로 장비사가 제시한 고정 시간 기법(Fixed time technique)과 조영제 추적 기법(Bolus tracking technique)을 비교하여 환자의 피폭선량을 분석하고자 하였으며, 조영제 추적 기법의 유용성과 최적의 조영증강 구간을 구현하는 Time graph를 알아보기 위한 것이다. 환자에서는 PCT의 $CTDI_{VOL}$은 고정시간기법에서 431.72mGy, Bolus tracking에서 323.61mGy로 측정되었고, DLP값은 고정시간기법에서 $1243.47mGy{\cdot}cm$, Bolus tracking에서 $932mGy{\cdot}cm$로 측정되었다. Time graph는 고정시간기법에서 다양하게 나타났으나, Bolus tracking 기법에서는 최적의 Time graph를 얻을 수 있었으며, 뇌 관류 CT검사 시 Bolus tracking기법을 적용하여 피폭선량을 25% 정도 감소시킬 수 있었다.

• International Journal of Internet, Broadcasting and Communication
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• 제10권2호
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• pp.1-6
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• 2018

The following research questions are examined in this paper. What hinders quality metadata generation and metadata interoperability? What kind of semantic representation technique can be utilized in order to enhance metadata quality and semantic interoperability? This paper suggests a way of handling semantic ambiguity for metadata generation. The conceptual graph is utilized to disambiguate semantic ambiguities caused by isolation of a metadata element and its corresponding definition from the relevant context. The mechanism introduced in this paper has the potential to alleviate issues dealing with inconsistent metadata application and interoperability across digital collections.

• Journal of Information Processing Systems
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• 제7권1호
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• pp.75-84
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• 2011

The enhanced pyramid graph was recently proposed as an interconnection network model in parallel processing for maximizing regularity in pyramid networks. We prove that there are two edge-disjoint Hamiltonian cycles in the enhanced pyramid networks. This investigation demonstrates its superior property in edge fault tolerance. This result is optimal in the sense that the minimum degree of the graph is only four.

• 한국ITS학회 논문지
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• 제17권2호
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• pp.87-97
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• 2018

많은 승객들이 이용하는 대중교통수단인 버스의 위험운전을 체계적으로 평가 및 진단하기 위한 시스템은 현재까지 매우 미흡한 상황이다. 본 연구는 실제 고속버스 운행기록장치(DTG, Digital Tacho Graph) 자료를 활용하여 버스 위험운전의 특성과 패턴에 대해 분석하였다. 위험운전 8개 유형에 대해 시간대별, 요일별, 날씨별 분포를 분석한 결과, 급가속(61.3%), 급좌우회전(20.1%), 급감속(15.1%) 유형이 대부분을 차지하였으며, 새벽시간대, 금요일, 맑은 날에 각각 위험운전이 더 많이 발생하는 패턴을 보였다. 이어서 통계분석을 통해 위험운전 유형별 상관성과 시간대별 발생건수의 차이를 규명하였으며, 위험운전의 정도에 따라 3개 그룹을 제시하였다. 본 연구의 결과는 향후 안전운전 교육기관에서 운전 시뮬레이터를 통한 신뢰성 있는 진단 및 교육을 수행하기 위한 참고자료로 활용될 수 있을 것이다.