• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.1
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• pp.20-24
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• 2009

Objective: In this study, the differences between two reconstruction methods were analyzed by comparing image uniformity and contrast according to Iteration and Subset, which were altered through the Iterative method and True X method, used in Siemens' PET/CT studies. Methods: The Phantom images were obtained by exposure for two minutes per one bed. To determine the image uniformity, the Coefficient of variance was used. Also, in order to compare the contrast value, we measured and analyzed the ratio of the SUV mean of Phantom image's hot spheres and the background. Results: Under the same reconstruction conditions (Iteration and Subset) of CV, the Iterative method was higher than the True X method. In the comparison of the SUV mean ratio of the background and hot sphere, the True X method had a closer rate than the Iterative method. Conclusion: The newly developed True X reconstruction method is better than the previously used Iterative method in terms of uniformity and contrast. However, the date for this study was only obtained using the Phantom device. In order to obtain more accurate and useful information from the experiment, further research should be conducted. Also, it is necessary to find the appropriate standards for Iteration and Subset for further experimentation.

• Progress in Medical Physics
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• v.20 no.2
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• pp.62-71
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• 2009

Recently, optical coherence tomography (OCT) has demonstrated considerable promise for the noninvasive assessment of biological tissues. However, OCT images difficult to analyze due to speckle noise. In this paper, we tested various image processing techniques for speckle removal of human and rabbit cartilage OCT images. Also, we distinguished the images which get with methods of image segmentation for OCT images, and found the most suitable method for segmenting an image. And, we selected image segmentation suitable for OCT before image reconstruction. OCT was a weak point to system design and image processing. It was a limit owing to measure small a distance and depth size. So, good edge matching algorithms are important for image reconstruction. This paper presents such an algorithm, the chamfer matching algorithm. It is made of background for 3D image reconstruction. The purpose of this paper is to describe good image processing techniques for speckle removal, image segmentation, and the 3D reconstruction of cartilage OCT images.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.363-373
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• 2000

It is necessary to employ the interpolation technique to resolve problems, which are associated with the characteristic locus in time-distance space, in the unsteady analysis of pipe flow. Various interpolation methods such as linear timeline interpolation, linear spaceline interpolation, wave speed adjustment, cubic spaceline interpolation and cubic timeline interpolation have been suggested and tested to investigate the interpolation error. Performance of various interpolation techniques was evaluated both a single pipeline and a complex one. The range of error was calculated as the courant number varied between 0 and 1 in a single pipeline. Reorganization of computational element and proper selection of interpolation method are found to be prerequisites for the effective computation of unsteady analysis.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.3
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• pp.401-408
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• 2009

A study for 3D-reconstruction and providing the geospatial information is in progress to many fields recently. For efficient providing the geospatial information, the present information has to be updated and be revised and then the latest geospatial information needs to be acquired economically. Especially, LiDAR system utilized in many study has a advantage to collect the 3D spacial data easily and densely that is possible to supply to the geospatial information. The 3D data of LiDAR is very suitable as a data for presenting 3D space, but in case of using the data without converting, the high performance processor is needed for presenting 2D forms from point data composed by 3D data. In comparison, basically the raster data structure of 2D form is more efficient than vector structure in cheap devices because of a simple structure and process speed. The purpose of this study, in case of supplying LiDAR data as 3D data, present the method that reconstructs to 2D raster data and convert to compression data applied by th tree construction in detail.

• Journal of Korea Spatial Information System Society
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• v.10 no.1
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• pp.15-28
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• 2008

In ubiquitous sensor networks(USN) environment, it is essential to process region query for user-demand services. Using R-tree is a preferred technique to process region query for in-network query environment. In USN environment, USN middleware must select sensors that transfers region query with accuracy because the lifetime of sensors is that of whole sensor networks. When R-tree is used, however, it blindly passes the region query including non-existent sensors where MBR(Minimum Boundary Rectangle) of R-tree is Intersected by region of query. To solve in this problem, we propose a reconstruction of region query method which is a trie-structured Quad tree in the base station that includes sensors in region of query select with accuracy. We observed that the proposed method delays response time than R-tree, but is useful for reducing communication cost and energy consumption.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.1 s.39
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• pp.3-7
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• 2007

To deal with the modern intellectual criminal acts, various efforts have been tried. Especially, it is not difficult to watch the recent activities to analyze the criminal characteristics spatially using computing and GIS technology. In this study, the spatial features and patterns of crime are investigated. Based on the real criminal record in Seoul Korea, the crime is reconstituted with four major categories such as assault, larceny, robbery, and rape. Then the variables are derived based on the theory of criminology. The kernal density analysis is performed to investigate the criminal distribution, and the correlation between the main criminal causes and the criminal outbreak is examined by buffering analysis. In addition, the land price and land usages are correlated with social-economic factors of criminal patterns to produce the final crime map.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07b
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• pp.550-552
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• 2005

실감 재현이 중요한 가상현실 응용에서는 사용자에게 고급 그래픽 환경을 제시하고 사용자의 인터랙션에 즉각적인 피드백을 제공함으로서 실재감과 몰입감을 증대시키는 연구가 진행되어왔다. 실재감, 공간감 전달을 위해 시각과 청각을 함께 활용하는 것이 효과적이나, 가상공간의 특징을 반영한 3차원 사운도 재현 연구는 국내외 통틀어 초기단계에 머물러 있다. 실재감과 공간감을 반영한 3차원 사운드의 재현을 위해서는 음원의 전파, 반사, 잔향 풍의 계산이 사용자의 인터랙션에 따라 새롭게 계산되어야한다. 그러나 사운드 전파경로와 공간을 이루는 모든 폴리곤들과의 충돌을 검사하며 반사 등을 계산하는 것은 실시간성이 중요한 가상현실응용에서는 무리가 따르므로 실 시간성을 보장하기 위한 계산량 축소가 요구된다. 본 논문에서는 다수의 음원이 존재하는 복잡한 가상공간에서의 3차원 사운드를 재현하기 위하여 사운드 신과 계산에 필요한 최소한의 정보를 가지는 오디오 씬 그라프의 공간을 재구성하고 다수의 음원을 대상으로 음원 축소 및 군집화를 적용하여 3차원 사운드효과를 실시간으로 재현하는 알고리즘을 제안한다.

• The KIPS Transactions:PartA
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• v.14A no.3 s.107
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• pp.133-140
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• 2007

The SWBF(shrink-wrapped boundary face) algorithm is a recent mesh reconstruction method for constructing a surface model from a set of unorganized 3D points. In this paper, we point out the surface duplication problem of SWBF and propose an improved mesh reconstruction scheme. Our method tries to classify the non-boundary cells as the inner cell or the outer cell, and makes an initial mesh without surface duplication by adopting the improved boundary face definition. To handle the directional unbalance of surface sampling density arise in typical 3D scanners, two dimensional connectivity in the cell image is introduced and utilized. According to experiments, our method is proved to be very useful to overcome the surface duplication problem of the SWBF algorithm.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.4-6
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• 2002

최근 폭발적으로 증가하는 대량의 정보를 효율적으로 관리하기 위해서 서버에 개별적으로 연결되던 저장장치를 고속의 전용 네트워크에 직접 연결하고 이를 여러 서버가 공유하는 SAN(Storage Area Network)이 등장했다. SAN을 보다 효과적으로 활용할 수 있도록 SAN 운영체제들은 여러 저장장치를 하나의 커다란 저장장치로 보이게 하는 저장장치 가상화를 지원한다. 저장장치 가상화의 핵심적인 역할을 하는 것이 바로 논리볼륨 관리자이다. 논리볼륨 관리자는 논리주소 블록을 실제 디스크의 물리블록으로 매핑시키는 매핑 관리자를 통해 가상화를 실현한다. 이 논문에서는 효율적인 논리볼륨 관리자를 위해 매핑 관리자와 자유공간 관리자의 기능 향상에 대한 방법을 찾고 이를 반영한 매핑 관리자와 자유공간 관리자를 설계하고 구현한다. 더불어 이 논문의 매핑 관리기법은 특정 시점의 볼륨이미지를 유지할 수 있는 스냅샷과 시스템을 정지시키지 않고 SAN에 디스크를 추가할 수 있는 온라인 재구성 기능을 지원한다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2006.05a
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• pp.112-115
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• 2006

현대사회는 지능적으로 고도화되는 범죄에 대응하기 위하여 범죄 현상을 분석하려는 노력이 다각적으로 행해지고 있다. 컴퓨팅 기술과 GIS 기술을 이용한 범죄의 공간적 특성을 분석하려는 연구는 범죄 분야에서 최근 관심을 가지는 부분이다. 본 연구에서는 다양한 공간적인 특성이 나타나는 지역을 선정하여 범죄분포의 특성을 밝혀보고자 한다. 범죄는 발생 빈도가 높은 폭력, 절도, 강도, 성폭행의 범죄에 대해서 재구성하였으며 변수 도출을 위한 이론적 배경은 생활양식-일상이론과 환경범죄학을 기초로 하였다. 분석기법으로는 Hot spot 을 이용하여 범죄의 분포 형태를 분석하였으며 Buffer 분석을 하여 범죄 요인과 범죄 사이의 상관관계를 도출해 보았다.