• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3B
• /
• pp.183-198
• /
• 2006

We define the incomplete medium sharing system as a multi-channel shared medium communication system where constraints are imposed to the set of channels that may be allocated to some transmitter-receiver node pairs. To derive a centralized MAC scheme of a incomplete medium sharing system, we address the problem of optimal channel allocation The optimal channel allocation problem is then translated into a max-flow problem in a multi-commodity flow graph, and it is shown that the optimal solution can then be obtained by solving a linear programming problem. In addition, two suboptimal channel allocation schemes are proposed to bring down the computational complexity to a practical/feasible level; (1) one is a modified iSLIP channel allocation scheme, (2) the other is sequential channel allocation scheme. From the results of a extensive set of numerical experiments, it is found that the suboptimal schemes evaluate channel utilization close to that of the optimal schemes while requiring much less amount of computation than the optimal scheme. In particular, the sequential channel allocation scheme is shown to achieve higher channel utilization with less computational complexity than . the modified iSLIP channel allocation scheme.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.1
• /
• pp.110-114
• /
• 2010

We describe a new method for text categorization using TextRank algorithm. Text categorization is a problem that over one pre-defined categories are assigned to a text document. TextRank algorithm is a graph-based ranking algorithm. If we consider that each word is a vertex, and co-occurrence of two adjacent words is a edge, we can get a graph from a document. After that, we find important words using TextRank algorithm from the graph and make feature which are pairs of words which are each important word and a word adjacent to the important word. We use classifiers: SVM, Na$\ddot{i}$ve Bayesian classifier, Maximum Entropy Model, and k-NN classifier. We use non-cross-posted version of 20 Newsgroups data set. In consequence, we had an improved performance in whole classifiers, and the result tells that is a possibility of TextRank algorithm in text categorization.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.6 s.44
• /
• pp.227-235
• /
• 2006

MPEG-21's digital item adaptation technology becomes a new way for universal multimedia access. It needs transcoder to change media resource's format and so on according to delivery context Then, the use of heavy transcoder with various transcoding functions integrated into one altogether is so complicated and difficult in supporting universal multimedia access. Unit transcoder Is useful is to resolve this question, in which a transcoder has only one transcoding function. This requires considering how to compose a set of unit transcoders. Thus, given a set for end-to-end different service quality pairs according to the character of application as defined by user, this study suggests how to compose complete unit transcoders that can always create one and more transcoding path(s) for each pair in the set. This method has a question of creating too many transcoding paths for each pair or end-to-end different service quality. Thus, this study also suggests the algorithm that generates minimum unit transcoder sets to support multimedia adaptation with minimum unit transcoder. The algorithm suggested was implemented into multimedia stream engine, and this paper describes the results of experiment for this algorithm.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.41 no.4
• /
• pp.23-30
• /
• 2004

Ontologies play an important role in the Semantic Web by providing well-defined meaning to ontology consumers. But as the ontologies are authored in a bottom-up distributed mimer, a large number of overlapping ontologies are created and used for the similar domains. Ontology sharing and reuse have become a distinguished topic, and ontology merging and alignment are the solutions for the problem. Ontology merging and alignment algorithms previously proposed detect conflicts between concepts by making use of only local syntactic information of concept names. And they depend only on a semi-automatic approach, which makes ontology engineers tedious. Consequently, the quality of merging and alignment tends to be unsatisfying. To remedy the defects of the previous algorithms, we propose a new algorithm for ontology merging and alignment which uses local and global semantic set of a concept. We evaluated our algorithm with several pairs of ontologies written in OWL, and achieved around 91% of precision in merging and alignment. We expect that, with the widespread use of web ontology, the need for ontology sharing and reuse ill become higher, and our proposed algorithm can significantly reduce the time required for ontology development. And also, our algorithm can easily be applied to various fields such as ontology mapping where semantic information exchange is a requirement.

• The Journal of the Korea Contents Association
• /
• v.12 no.2
• /
• pp.40-51
• /
• 2012

Recently, many users discuss and argue with others using replying comments. This implies that a series of comments can be a new source of information since various opinions can be appeared in the dispute. It is important to understand the implicit dispute structure immanent in the comment set. In this paper, we examine the characteristics of disputes using replying comments in the Internet forum sites using a set of test articles with the comments collected from SketicalLeft and Agora, which are famous Internet forum sites in Korea. And we propose a new method for detecting and visualizing the dispute sections and relations from a large set of replying comments. To show the performance of our method, we measured precision, recall, and F-measure. According to the experimental results, the F-measures of the detection of the comments in dispute are about 0.84 (SketpcialLeft) and 0.83 (Agora); those of the detection of the commenter pairs in dispute are 0.75 (SketpcialLeft) and 0.82 (Agora), respectively. Since our method exploits the temporal order of commenters to detect the disputes, it is not dependent on the host language nor on the typos in comments. Also, our method can help the readers to grasp the structure of controversy hidden in the comment set through the visualized view.

• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.9
• /
• pp.745-752
• /
• 2016

We suggest an efficient Simultaneous Localization and 3D Polygon Map Building (SLAM) method with Kinect depth sensor for mobile robots in indoor environments. In this method, Kinect depth data is separated into row planes so that scan line segments are on each row plane. After grouping all scan line segments from all row planes into line groups, a set of 3D Scan polygons are fitted from each line group. A map matching algorithm then figures out pairs of scan polygons and existing map polygons in 3D, and localization is performed to record correct pose of the mobile robot. For 3D map-building, each 3D map polygon is created or updated by merging each matched 3D scan polygon, which considers scan and map edges efficiently. The validity of the proposed 3D SLAM algorithm is revealed via experiments.

• Journal of the Korean earth science society
• /
• v.24 no.1
• /
• pp.30-35
• /
• 2003

The preliminary results of the study on the physics of rain using disdrometer data are shown for an area located on the northern coastal board of Macei${\acute{o}}$, Alagoas (9$^{\circ}$33'17.24' and 35$^{\circ}$46'54.84' W), at approximately 80 meters above the sea level. The data were obtained during January 2002 using a disdrometer RD-69 (Joss-Waldvogel). After definining the criteria for determining rain type (convective and stratiform), a set of Z-R pairs was analyzed for estimating the Z-R relation for each rain type. The results were quite similar to those for other regions of the globe. This preliminary analysis will be used to study the structure of rain with the meteorological radar as well as to permit a better understanding of the physics of tropical rain.

• The Plant Pathology Journal
• /
• v.27 no.4
• /
• pp.367-371
• /
• 2011

Multiplex PCR assays were developed for the simultaneous detection of ten important Korean quarantine phytoplasmas. The species-specific primers were designed based on ribosomal protein, putative preprotein translocase Y, immunodominant protein, elongation factor TU, chaperonin protein and the 16S rRNA genes of 'Candidatus (Ca.) Phytoplasma' species. Three main primer sets were prepared from ten designed primer pairs to limit nonspecific amplification as much as possible. The multiplex PCR assay using the three primer sets successfully amplified the correct conserved genes for each 'Ca. Phytoplasma' species. In addition, ten important 'Ca. Phytoplasma' species could be easily determined by recognizing band patterns specific for each phytoplasma species from three primer sets. Moreover, a high sensitivity of multiplex PCR for each primer set was observed for samples containing a low DNA concentration (10 ng/${\mu}l$). This study provides the useful multiplex PCR assay as a convenient method to detect the presence of ten important quarantine phytoplasmas in Korea.

• Transactions of Materials Processing
• /
• v.20 no.2
• /
• pp.160-166
• /
• 2011

Weight reduction while maintaining functional requirements is one of the major goals in the automotive industry. The use of lightweight magnesium alloys offers great potential for reducing weight because of the low density of these alloys. However, the formability and the surface quality of the final magnesium alloy product for auto-body structures are not acceptable without a careful optimization of the design parameters. In order to overcome some of the main formability limitations in the stamping of magnesium alloys, a new approach, the so-called "hybrid technology", has been recently proposed for body-in-white structural components. Within this approach, necessary level of mechanical joining can be obtained through the use of lightweight material-steel adhesion promoters. This paper presents the development process of an automotive hybrid hood assembly using magnesium alloy sheets. In the first set of material pairs, the selected materials are magnesium alloy AZ31B alloy and steel(SGCEN) as inner and outer panels, respectively. In order to optimize the design of the inner panel, the stamping process was analyzed with the finite element method (FEM). Laser welding by CW Nd:YAG were used to join the magnesium alloy sheets. Based on the simulation results and mechanical test results of the joints, the determination of die design variables and their influence on formability were discussed. Furthermore, a prototype based on the proposed design was manufactured and the static stiffness test was carried out. The results demonstrate the feasibility of the proposed hybrid hood with a weight reduction of 25.7%.

• 한국HCI학회:학술대회논문집
• /
• 2009.02a
• /
• pp.278-284
• /
• 2009

Multimodal data to have several modalities such as videos, images, sounds and texts for one contents is increasing. Since this type of data has ill-defined format, it is not easy to represent the crossmodal information for them explicitly. So, we proposed new method to extract and analyze vision-language crossmodal association information using the documentaries video data about the nature. We collected pairs of images and captions from 3 genres of documentaries such as jungle, ocean and universe, and extracted a set of visual words and that of text words from them. We found out that two modal data have semantic association on crossmodal association information from this analysis.