• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.211-218
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• 1998

In this paper, we analyze various errors in prediction results of ray tracing propagation model for microcellular environments. It is shown that improper electrical parameters of building materials and limitations of diffraction orders can cause high errors in prediction results. Especially, the effect of errors in building database on prediction results is considered in detail. It is also shown that the prediction error increases as the resolution of building map data is getting worse, and the error is analyzed depending on LOS and NLOS domains. Based on the results obtained by the analysis developed in this paper, 5 m resolution is suitable for the building map data if the maximum prediction error is required to be below 6 dB.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.218-221
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• 2014

기존의 지역기반 스테레오 정합 방법은 정합에 사용하는 정합창 크기에 따라 다양한 결과를 갖게 된다. 특히 사용하는 정합창의 크기가 커질수록 영상의 잡음에 강인하지만 객체의 경계부분이 모호해지는 단점을 갖고 있다. 본 논문은 고정된 크기의 정합창을 사용하는 지역기반 스테레오 정합 방법과 다른 방법을 제안한다. 제안한 방법은 영상의 경계를 검출하는 알고리즘을 이용하여 경계부분에는 작은 크기의 정합창을 사용한 변이값을 적용하고 경계가 없는 부분은 큰 크기의 정합창을 사용하여 얻은 변이값을 적용하도록 하였다. 경계를 검출하는 과정에서 본 논문은 AND 연산을 사용하여 최대한 객체의 테두리만을 나타내는 경계값을 구하도록 하였다. 또한 두 가지 크기의 정합창을 이용함으로써 발생하는 복잡도 증가를 감소시키기 위해 기존의 SAD 연산 알고리즘을 수정하여 복잡도를 감소시켰다. 본 논문에서 사용한 정합창의 크기는 $5{\times}5$와 $15{\times}15$이며 실험결과 제안한 방법은 $15{\times}15$ 정합창을 사용한 결과와 비교하여 변이지도에서 객체의 경계부분은 더 잘 살리면서 수행시간을 줄여 효율적인 정합결과를 얻어냈다.

• The KIPS Transactions:PartD
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• v.18D no.6
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• pp.501-508
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• 2011

A knowledge map, which has been recently applied in various fields, is discovering characteristics hidden in a large amount of information and showing a tangible output to understand the meaning of the discovery. In this paper, we suggested a knowledge map for research trend analysis based on keyword-relation networks which are constructed by using a database of the domestic journal articles in the computer engineering field from 2000 through 2010. From that knowledge map, we could infer influential changes of a research topic related a specific keyword through examining the change of sizes of the connected components to which the keyword belongs in the keyword-relation networks. In addition, we observed that the size of the largest connected component in the keyword-relation networks is relatively small and groups of high-similarity keyword pairs are clustered in them by comparison with the random networks. This implies that the research field corresponding to the largest connected component is not so huge and many small-scale topics included in it are highly clustered and loosely-connected to each other. our proposed knowledge map can be considered as a approach for the research trend analysis while it is impossible to obtain those results by conventional approaches such as analyzing the frequency of an individual keyword.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.5
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• pp.245-256
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• 2002

Shadows are important elements in producing a realistic image. Generation of exact shapes and positions of shadows is essential in rendering since it provides users with visual cues on the scene. It is also very important to be able to create soft shadows resulted from area light sources since they increase the visual realism drastically. In spite of their importance. the existing shadow generation algorithms still have some problems in producing realistic shadows in real-time. While image-based rendering techniques can often be effective1y applied to real-time shadow generation, such techniques usually demand so large memory space for storing preprocessed shadow maps. An effective compression method can help in reducing memory requirement, only at the additional decoding costs. In this paper, we propose a new image-barred shadow generation method based on image warping. With this method, it is possible to generate realistic shadows using only small sizes of pre-generated shadow maps, and is easy to extend to soft shadow generation. Our method will be efficiently used for generating realistic scenes in many real-time applications such as 3D games and virtual reality systems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.208-218
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• 2017

This study aims to develop the Vehicle Local Dynamic Map (V-LDM) and demonstrate its performance for providing dynamic map data efficiently to the vehicle control module. Firstly, the concept of the in-vehicle LDM has been established and then the system has been carefully designed according to the international standards. The high-precision digital map embedded in LDM has been designed to incorporate the lane-level information of road network, and the Dynamic Map protocol (DM protocol) which is a message protocol including the road data with dynamic traffic event data has been defined. The performance test of the proposed system has been conducted in the uninterrupted road section of Kyungbu expressway, showing that both of the data size and the elapsed time to finish the process are almost linearly proportional to the length of target road. Finally, it is recommended that the length of target road for DM protocol be less than 250m.

• Journal of the Korea Society of Computer and Information
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• v.14 no.11
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• pp.135-144
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• 2009

In this paper, a methodology for the risk probability map generation of the crime prevention to be subject to the urban area in the group residential area is presented. The interpretation key is set up to the distinctive feature distinguishing with the unaided eye based on the object composing with the urban area information such as the topology, the facility, and the characteristic information of the corresponding area by analyzing the crime prevention case occurred by gone. This interpretation key is generated, and this information is applied to another area equally, and so, the risk probability map for the crime prevention and the disaster prevention is generated. At this time, the object interpretation key for the urban area information is divided into the various size cell by the crime prevention case. and the risk index according with this cell is set up. Also, the generated various risk probability map is unified, and the integration risk probability map is generated.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.191-194
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• 2005

본 논문에서는 방송 영상에서 조명효과와 크기변화 등에 강인한 얼굴패턴 검출기법을 제시한다. 제안된 얼굴검출 모델은 영상 전처리 과정과 얼굴패턴 검출 과정으로 이루어진다. 전처리 과정은 조명변화에 대한 보정기능과 다중필터에 의한 후보영역 선별기능으로 구분된다. 얼굴패턴 검출과정은 다단계의 특징지도 생성과정과 패턴분류 과정으로 이루어진다. 특징지도를 생성하기 위하여 가보(Gabor) 필터계층을 포함하는 CNN(Convolutional Neural Networks)모델을 도입하였다. 다양한 배경을 고려한 효과적인 학습을 위하여 본 논문에서는 억제성의 뉴런(Inhibitory neuron)을 포함하는 구조의 CNN모델을 적용한다. CNN으로부터 추출되는 특징집합은 최종 단계에서 WFMM(Weighted Fuzzy Min Max) 모델을 사용하여 분류된다. 이때 사용되는 특징집합의 크기는 분류기의 규모 및 계산량의 결정적인 역할을 준다. 이에 본 연구에서는 최종 분류 과정에 사용되는 특징의 수를 효과적으로 줄이기 위해 FMM모델을 사용하는 적응적인 특징 선별 기법을 제안한다. 또한 실제 영상을 통한 실험결과로부터 제안된 이론의 타당성을 고찰한다.

• Journal of KIISE:Software and Applications
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• v.32 no.11
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• pp.1121-1135
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• 2005

This paper proposes a moving object extraction method using the contrast map and salient points. In order to make the contrast map, we generate three-feature maps such as luminance map, color map and directional map and extract salient points from an image. By using these features, we can decide the Attention Window(AW) location easily The purpose of the AW is to remove the useless regions in the image such as background as well as to reduce the amount of image processing. To create the exact location and flexible size of the AW, we use motion feature instead of pre-assumptions or heuristic parameters. After determining of the AW, we find the difference of edge to inner area from the AW. Then, we can extract horizontal candidate region and vortical candidate region. After finding both horizontal and vertical candidates, intersection regions through logical AND operation are further processed by morphological operations. The proposed algorithm has been applied to many video sequences which have static background like surveillance type of video sequences. The moving object was quite well segmented with accurate boundaries.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.3
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• pp.229-236
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• 2001

One of the basic tasks in hydrological analysis is to delineate drainage basins and channel networks. Characteristics of channel networks and drainage basin parameters have been used widely in hydrologic calculation and modeling. DEMs(Digital Elevation Models) are generally used to automatically map the channel networks and to delineate drainage basins. This paper presents an effort to analyze basin characteristics using various DEMs. The quantitative analysis of channel networks begins with Horton's method of classifying stream according to Horton orders in hydro-geomorphy. HGSIS(Hydro-Geo-Spatial Information System) is possible to extract parameters. Usually, hydrologists. surveyors and GSIS researchers have some difficulties in accessing satellite images and in extracting DEMs from them. Therefore, the extracted DEMs from contours of digital map is widely used to have the basic works of hydrological analysis. This study presents proper DEMs to calculate Horton's orders, width function, drainage area, main channel length, total channel length, basin elevation and basin slope at digital map of 1:25,000 scale.

• Journal of Educational Research in Mathematics
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• v.19 no.1
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• pp.25-43
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• 2009

The fraction concept consists of various meanings and is one of the abstract and difficult in elementary school mathematics. This study intends to find out the implication for introducing the fraction concept by comparing mathematics textbooks of Korea and Singapore. Both countries' students peformed well in recent TIMMSs. Some implications are as follows; The term 'equal' is not defined and the results of various 'equal partitioning' activities can not easily examined in Korea's mathematics textbook. And contexts of introducing fractions as a quotient and a ratio are unnatural in Korea's mathematics textbook in comparison with Singapore's mathematics textbook. So these ideas should be reconsidered in order to seek the direction for improvement of it. And Korea's textbooks need the emphasis on the fraction as a measure and on constructing fraction concept by unit fraction.