• Journal for History of Mathematics
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• v.13 no.2
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• pp.73-86
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• 2000

This paper introduces an hypermedia program supportable for teaching secondary and upper secondary level geometry. This program links users to files written in other softwares and internet web sites to provide information and exploratory environments with softwares. The linkage with the interactive dynamic software(GSP) files to teach hyperbolic geometry is illustrated with sample screens.

• Proceedings of the KGS Conference
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• 2004.05a
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• pp.103-103
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• 2004

With the emergency of geographic information systems (GIS), the traditional layer based data model can only contain the spatial geometry and thematic attributes of phenomena. In real world, geographic phenomena have not only spatial geometry and thematic attribute but the temporal situation and the relationship between each phenomenon. (omitted)

• Proceedings of the Korean Information Science Society Conference
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• 2008.06a
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• pp.347-348
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• 2008

• Journal of the Korea Society of Computer and Information
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• v.6 no.1
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• pp.51-59
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• 2001

In this paper, performance of the double circular array antenna was analyzed, which has sharp directivity with specific direction and is compatible to shape pencil beam. The character of each array geometry which N numbers of isotropic point source is arranged in planar with type of a square, circular and double circular was compared and analyzed. As a result, we fined that double circular geometry was good performance rather than square and circular array geometry in the point of directivity. SLL and HPBW.

• Journal of the Korean Data and Information Science Society
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• v.18 no.2
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• pp.375-384
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• 2007

As teachings that use the ICT are more popular, many studies on the dynamic geometry environment(DGE) are under way. An important factor emphasized in the studies is to practical use learning activities of learners. In this study, we first define the learning history data in DGE. Second we develop a prototype of the DGE that is able to collect and analyze the learning history data automatically. The environment enables not only to grasp leaning history but also to create and manage new learning objects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.989-991
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• 2017

This letter proposes the method for approximating a stochastic geometry based downlink multicell network performance in a wide range of interference and noise levels. This method facilitates the simplification of a multicell network design problem for the base station density and transmit power.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.179-184
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• 2004

High-resolution satellite imagery are used in various application field such as generation of DEM, orthophto, and three dimensional city model. To define the relation between image and object space, sensor modelling and generation of the epipolar image is essential processes. As the header information or physical sensor model becomes unavailable for the end users due to the national security or commercial purpose, generation of epipolar images without these information becomes one of important processes. In this study, epipolar geometry is generated and analysed by applying two generalized sensor models; parallel and parallel-perspective model Epipolar equation of the parallel model has linear property which is relatively simple; Epipolar geometry of the parallel-perspective model is non-linear. This linear property enable us to generate epipolar image efficiently.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.857-859
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• 2015

In this letter, we consider a directional routing protocol that reduces the duplicated packets for AODV-based flooding in the course of establishing the end-to-end route in the multi-hop maritime ad-hoc networks. We propose an adaptive means of reducing the routing overhead subject to the node density and the target probability of successful routing that is analyzed by the stochastic geometry.

• Journal of Information Science Theory and Practice
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• v.7 no.2
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• pp.32-39
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• 2019

A convolutional neural network (CNN) has been widely used in facial expression recognition (FER) because it can automatically learn discriminative appearance features from an expression image. To make full use of its discriminating capability, this paper suggests a simple but effective method for CNN based FER. Specifically, instead of an original expression image that contains facial appearance only, the expression image with facial geometry visualization is used as input to CNN. In this way, geometric and appearance features could be simultaneously learned, making CNN more discriminative for FER. A simple CNN extension is also presented in this paper, aiming to utilize geometric expression change derived from an expression image sequence. Experimental results on two public datasets (CK+ and MMI) show that CNN using facial geometry visualization clearly outperforms the conventional CNN using facial appearance only.

• Korean Journal of Computational Design and Engineering
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• v.4 no.1
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• pp.43-51
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• 1999

Producing the relevant information (features) from the CAD models of CAM, called feature recognition or extraction, is the essential stage for the integration of CAD and CAM. Most feature recognition methods, however, have problems in the recognition of intersecting features because they do not handle the intersection geometry properly. In this paper, we propose a machining feature recognition algorithm, which has a solid model consisting of orthogonal primitives as input. The algorithm calculates candidate features and constitutes the Intersection Geometry Matrix which is necessary to represent the spatial relation of candidate features. Finally, it recognizes machining features from the proposed candidate features dividing and growing systems using half space and Boolean operation. The algorithm has the following characteristics: Though the geometry of part is complex due to the intersections of design primitives, it can recognize the necessary machining features. In addition, it creates the Maximal Feature Volumes independent of the machining sequences at the feature recognition stage so that it can easily accommodate the change of decision criteria of machining orders.