• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1764-1773
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• 2018

A-PET is a quad-head PET scanner developed for use in small-animal imaging. The dimensions of its volumetric field of view (FOV) are $46.1{\times}46.1{\times}46.1mm^3$ and the gap between the detector modules has been minimized in order to provide a highly sensitive system. However, such a small FOV together with the quad-head geometry causes image quality degradation. The main factor related to image degradation for the quad-head PET is the mispositioning of events caused by the penetration effect in the detector. In this paper, we propose a precise method for modelling the system at the high spatial resolution of the A-PET using a LOR (line of response) based ML-EM (maximum likelihood expectation maximization) that allows for penetration effects. The proposed system model provides the detection probability of every possible ray-path via crystal sampling methods. For the ray-path sampling, the sub-LORs are defined by connecting the sampling points of the crystal pair. We incorporate the detection probability of each sub-LOR into the model by calculating the penetration effect. For comparison, we used a standard LOR-based model and a Monte Carlo-based modeling approach, and evaluated the reconstructed images using both the National Electrical Manufacturers Association NU 4-2008 standards and the Geant4 Application for Tomographic Emission simulation toolkit (GATE). An average full width at half maximum (FWHM) at different locations of 1.77 mm and 1.79 mm are obtained using the proposed system model and standard LOR system model, which does not include penetration effects, respectively. The standard deviation of the uniform region in the NEMA image quality phantom is 2.14% for the proposed method and 14.3% for the LOR system model, indicating that the proposed model out-performs the standard LOR-based model.

• Fire Science and Engineering
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• v.27 no.2
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• pp.25-30
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• 2013

'Heaundae Woosin Building' fire was the case that a fire breaking out on the $4^{th}$ floor spread out the $38^{th}$ floor which is a top story and the penthouse was destroyed by fire. After this fire, the fire safety for high rise buildings has been on the rise and several new laws and regulations related in the buildings were created. The study is to analyze Heaundae officetel building case using FDS which is one of the CFD programs for fire. The methodology of this study is to analyze the case comparing with fire spread and route from a virtual fire simulation and related articles and a video clip of actual scene fire. This study shows that a fire spreading on top of levels spent approximately 30 minutes and, which is similar to the actual fire case. Also the pattern of spread has similarity with the case. However, even if the actual fire case shows the fire pattern was "V shape", the smoke-view presents the fire dose not spread horizontally as much as the real fire case. The result shows uncertainty of the modeling based on many grids and a limitation of putting interior finish input sources and the direction of the wind might cause the difference. Also, to analyze factors influencing on a vertical fire, another fire modeling is performed by in condition of modeling environment considering concrete interior finish between buildings and no wind. The result presents the fire spread in smoke-view does not spread vertically as much as the actual case.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.228-237
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• 2013

In this paper, we propose a normalized cross correlation(NCC)-based multiview background subtraction method which is robust when an object and background have similar color. When the background of the capturing environment is not artificially composed, the regions in the background images which would be occluded by an object tends to have difference colors. The colors of those regions, however, becomes similar when an object enters the capturing environment. Based on this assumption, this paper proposes a concept of GoNCC(Graph of Normalized Cross Correlation). GoNCC is the distribution of NCC between a pixel in an image and pixels related by epipolar constraints with the pixel. The proposed multiview background subtraction method is performed by comparing GoNCC of the current images with the background images. To reduce computational complexity, we perform multiview background subtraction only to the pixels undetermined by single view background subtraction. Experimental results show that the proposed method is more robust to color similarity between an object and background than a single-view background subtraction method and a previous multiview background subtraction method.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.219-231
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• 2016

$^{99m}Tc$-DMSA planar scan that can analyze the functions of kidney quantitatively provides less information on a lesion than tomography scanning. Therefore, this study applied a high sensitivity all-purpose collimator that is sensitive to photonic signals to $^{99m}Tc$-DMSA and carried out a clinical scan with single photon emission computed tomography (SPECT). And diagnostic accuracy and time requirement of were analyzed to know the clinical usefulness of the applied scanning method. 10 subjects were intravenously injected with radiopharmaceutical product (1.0-1.2 MBq/kg) and scanned by a gamma camera with planar scanner (high resolution (HR)-mode, $256{\times}256$, 50 kcts/view, 4 image) and SPECT (HR / high sensitive (HS)-mode, $128{\times}128$, step and shoot, $180^{\circ}$, variable sec/angle, total 64 frame, OSEM reconstruction), respectively. The collected data was compared with an analysis program. The results showed that HS-mode SPECT detected total counts 1.8-5.6 times more than planar scan. Relative renal function evaluated based on the counts was not significantly different by two scanning methods (p=0.96) and it turned out that test time was shortened by 39% when HS-mode SPECT was used. Therefore, SPECT using HR, HS-mode collimator could analyze renal function more quantitatively than using planar scan and the former could diagnose the location information of a lesion more accurately than the latter as well as shortened test time requirement, which demonstrated the clinical usefulness of $^{99m}Tc$-DMSA renal SPECT using high sensitivity all purpose collimator.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.3 s.303
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• pp.39-52
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• 2005

In this paper, a registration method is presented to register partial 3D point clouds, acquired from a multi-view camera, for 3D reconstruction of an indoor environment. In general, conventional registration methods require a high computational complexity and much time for registration. Moreover, these methods are not robust for 3D point cloud which has comparatively low precision. To overcome these drawbacks, a projection-based registration method is proposed. First, depth images are refined based on temporal property by excluding 3D points with a large variation, and spatial property by filling up holes referring neighboring 3D points. Second, 3D point clouds acquired from two views are projected onto the same image plane, and two-step integer mapping is applied to enable modified KLT (Kanade-Lucas-Tomasi) to find correspondences. Then, fine registration is carried out through minimizing distance errors based on adaptive search range. Finally, we calculate a final color referring colors of corresponding points and reconstruct an indoor environment by applying the above procedure to consecutive scenes. The proposed method not only reduces computational complexity by searching for correspondences on a 2D image plane, but also enables effective registration even for 3D points which have low precision. Furthermore, only a few color and depth images are needed to reconstruct an indoor environment.

• The Journal of Korean Philosophical History
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• no.30
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• pp.311-344
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• 2010

Over 100 years in Mainland China, the 'traditional' thought and culture have been transformed from 'the past must be sublated' to 'the heritage must be preserved.' Today, China hopes to deal with the negative effects of industrial development such as the gap between rich and poor, and the absence of common values etc. through the reconstruction of traditional thought and culture, especially that of Confucianism. The Chinese government superficially accepts Confucianism for the purpose of the social stabilization and ongoing economic development while they keep the Socialism as the nation's ideological system. In the private sectors, there is endeavoring move to make the Chinese traditional thought and culture global paralleled to their economic growth. There are also scholars who find the cultural unification and the spiritual comfort from the restoration of the traditional thought and culture. They, so called 'the critical successionists' or 'the cultural conservativists,' believe that the traditional thought and culture could play a role in the Chinese modernization, and the new understanding and interpretation of their tradition could provide an alternative for their future. In my view, we need a careful survey on the view of the critical successionists or the cultural conservativists who regard tradition and culture as a power (力量). With this, we are required to investigate our own problems through the new understanding of our traditional thought and culture.

• Korean Journal of Remote Sensing
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• v.38 no.3
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• pp.283-298
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• 2022

As Synthetic Aperture Radar (SAR) image can be acquired regardless of the weather and day or night, it is highly recommended to be used for Automatic Target Recognition (ATR) in the fields of surveillance, reconnaissance, and national security. However, there are some limitations in terms of cost and operation to build various and vast amounts of target images for the SAR-ATR system. Recently, interest in the development of an ATR system based on simulated SAR images using a target model is increasing. Attributed Scattering Center (ASC) matching and template matching mainly used in SAR-ATR are applied to target classification. The method based on ASC matching was developed by World View Vector (WVV) feature reconstruction and Weighted Bipartite Graph Matching (WBGM). The template matching was carried out by calculating the correlation coefficient between two simulated images reconstructed with adjacent points to each other. For the performance analysis of the two proposed methods, the Synthetic and Measured Paired Labeled Experiment (SAMPLE) dataset was used, which has been recently published by the U.S. Defense Advanced Research Projects Agency (DARPA). We conducted experiments under standard operating conditions, partial target occlusion, and random occlusion. The performance of the ASC matching is generally superior to that of the template matching. Under the standard operating condition, the average recognition rate of the ASC matching is 85.1%, and the rate of the template matching is 74.4%. Also, the ASC matching has less performance variation across 10 targets. The ASC matching performed about 10% higher than the template matching according to the amount of target partial occlusion, and even with 60% random occlusion, the recognition rate was 73.4%.

• Journal of the Korean Arthroscopy Society
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• v.13 no.1
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• pp.8-13
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• 2009

Purpose: We used tibialis allograft for the reconstruction of ACL and used Hybrid femoral fixation utilizing $Endobutton^{(R)}$ and $Rigidfix^{(R)}$ for femoral fixation, and used $Retroscrew^{(R)}$ and additional fixation for tibial fixation to evaluate the clinical results. Materials and Methods: The ACL reconstruction were performed from February 2004 to February 2007 utilizing Hybrid femoral fixation and $Retroscrew^{(R)}$ and 32 patients, 32 cases which were available for year-long observation (12 to 25 months). The clinical results (Lysholm knee score, IKDC grade) and the radiologic results(bone tunnel expansion, Telos anterior displacement test) were evaluated. Results: The Lysholm knee score was improved from the average of $67.9{\pm}5.4$ points (range: 51~77) before operation and to $94.1{\pm}6.8$ points (range: 68~98) at the last follow up (p<0.05). 22 cases (69%) were evaluated normal (A), 9 cases (28%) were evaluated nearly normal (B) and only 1 case (3%) was evaluated not normal (C) at IKDC final evaluation and no case was evaluated abnormal. From $Telos^{(R)}$ stress x-ray evaluation, difference from the opposite knee was improved average 13.2 mm{\pm}5.8 (range: 6~21 mm) to average $3.4\;mm{\pm}2.8$ (range: 0~11 mm) after operation (p<0.05). The femoral and tibial tunnel were widened by 18.7% and 9.6% in the AP view and 12.4% and 8.5% in the lateral view, respectively (p<0.05). However, any statistic significance was not observed between bone tunnel expansion and knee joint functions (p>0.05). Conclusion: An ACL reconstruction with tibialis allograft using Hybrid femoral fixation and $Retroscrew^{(R)}$ enabled anatomical fixation of the graft tendon with satisfactory clinical results.

• Journal of Korean Orthopaedic Sports Medicine
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• v.9 no.1
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• pp.41-47
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• 2010

Purpose: To compare the obliquity of femoral tunnels prepared with transtibial (TT) versus anteromedial portal technique (AM) using x-ray in single-bundle anterior cruciate ligament (ACL) reconstruction. Materials and Methods: Among one-hundred thirty two patients who were undergoing ACL reconstruction from January 2007 to December 2009, thirty patients using TT and twenty patients using AM, those who had single-bundle ACL reconstruction, were evaluated with plain radiographs including anteroposterior, intercondylar notch and lateral view to compare the obliquity of bone tunnels. Results: The mean coronal obliquity of femoral tunnel for TT was $71^{\circ}$ (range; $65^{\circ}{\sim}77^{\circ}$), while for AM was $51^{\circ}$ (range; $39^{\circ}{\sim}60^{\circ}$) and the mean sagittal obliquity of femoral tunnel for TT was $22.7^{\circ}{\pm}7.8$, while for AM was $30.2^{\circ}{\pm}6.9$, their differences between them were statistically significant (P<0.05). However, there were no differences between two techniques on the tibial tunnel obliquity in coronal and sagittal plane. Conclusion: Anterior cruciate ligament reconstruction using AM portal technique allows more horizontally oriented and divergent femoral tunnel compared to that of transtibial technique. This seems to enable the graft placement into the femoral footprint and preserve the posterior cortical wall.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.2
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• pp.132-140
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• 2001

This paper proposes an efficient walktlu-ough animation from two images of the same scene. To make animation easily and fast, Tour Into the Picture(TIP) enables walkthrough animation from single image but lacks the reality of its foreground object when the viewpoint moves from side to side, and view morphing uses only 2D transition between two images but restricts its camera path on the line between two views. By combining advantages of these two image-based techniques, this paper suggests a new virtual navigation technique which enable natural scene transformation when the viewpoint changes in the side-to-side direction as well as in the depth direction. In our method, view morphing is employed only in foreground objects , and background scene which is perceived carelessly is mapped into cube-like 3D model as in TIP, so as to save laborious 3D reconstruction costs and improve visual realism simultaneously. To do this, we newly define a camera transformation between two images from the relationship of the spidery mesh transformation and its corresponding 3D view change. The result animation shows that our method creates a realistic 3D virtual navigation using a simple interface.