• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.89-98
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• 2010

In the heterogeneous system of various wired or wireless network with IP-based backbone, the continuities of agreedon QoS for multimedia services should be guaranteed regardless of network types and terminal mobility through seamless vertical handover. This paper proposes a QoS provisioning mechanism called D-ISHO which guarantees the continuities of agreed-on QoS and seamless for multimedia services by considering both such characteristics as delay, loss rate and jitter per each service and such status as available band-width, call arrival rate and data transmission rate during the vertical handover. Simulation is done for performance analysis with the measure of handover failure rate and packet loss rate.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.9
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• pp.401-410
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• 2016

3D registration is a computer vision technique of aligning multi-view range images with respect to a reference coordinate system. Various 3D registration algorithms have been introduced in the past few decades. Iterative Closest Point (ICP) is one of the widely used 3D registration algorithms, where various modifications are available nowadays. In the ICP-based algorithms, the closest points are considered as the corresponding points. However, this assumption fails to find matching points accurately when the initial pose between point clouds is not sufficiently close. In this paper, we propose a new method to solve this problem using the 6D distance (3D color space and 3D Euclidean distances). Moreover, a color segmentation-based adaptive sampling technique is used to reduce the computational time and improve the registration accuracy. Several experiments are performed to evaluate the proposed method. Experimental results show that the proposed method yields better performance compared to the conventional methods.

• Journal of Korea Multimedia Society
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• v.16 no.12
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• pp.1454-1464
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• 2013

In this paper, we propose a rapid rigid registration method for the fusion visualization of intra-operative 2D XA and pre-operative 3D CTA images. In this paper, we propose a global movement estimation based on a trilateration for the fast and robust initial registration. In addition, the principal axis of each image is generated and aligned, and the bounding box of the vascular shape is compared for more accurate initial registration. For the fine registration, two images are registered where the distance between two vascular structures is minimized by selective distance measure. In the experiment, we evaluate a speed, accuracy and robustness using five patients' data by comparing the previous registration method. Our proposed method shows that two volumes can be registered at optimal location rapidly, and robustly comparing with the previous method.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.114-122
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• 2011

We propose an automatic localization technique based on Uniform Arc Length Sampling (UALS) of 360 degree range sensor data. The proposed method samples 3D points from dense a point-cloud which is acquired by the sensor, registers the sampled points to a digital surface model(DSM) in real-time, and determines the location of an Unmanned Ground Vehicle(UGV). To reduce the sampling and registration time of a sequence of dense range data, 3D range points are sampled uniformly in terms of ground sample distance. Using the proposed method, we can reduce the number of 3D points while maintaining their uniformity over range data. We compare the registration speed and accuracy of the proposed method with a conventional sample method. Through several experiments by changing the number of sampling points, we analyze the speed and accuracy of the proposed method.

• Imaging Science in Dentistry
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• v.53 no.1
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• pp.21-26
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• 2023

Purpose: A fully digital approach to oral prosthodontic rehabilitation requires the possibility of combining (i.e., registering) digital documentation from different sources. This becomes more complex in an edentulous jaw, as fixed dental markers to perform reliable registration are lacking. This validation study aimed to evaluate the reproducibility of 1) intraoral scanning and 2) soft tissue-based registration of an intraoral scan with a cone-beam computed tomography (CBCT) scan for a fully edentulous upper jaw. Materials and Methods: Two observers independently performed intraoral scans of the upper jaw in 14 fully edentulous patients. The palatal vault of both surface models was aligned, and the inter-observer variability was assessed by calculating the mean inter-surface distance at the level of the alveolar crest. Additionally, a CBCT scan of all patients was obtained and a soft tissue surface model was generated using patient-specific gray values. This CBCT soft tissue model was registered with the intraoral scans of both observers, and the intraclass correlation coefficient(ICC) was calculated to evaluate the reproducibility of the registration method. Results: The mean inter-observer deviation when performing an intraoral scan of the fully edentulous upper jaw was 0.10±0.09 mm. The inter-observer agreement for the soft tissue-based registration method was excellent(ICC=0.94; 95% confidence interval, 0.81-0.98). Conclusion: Even when teeth are lacking, intraoral scanning of the jaw and soft tissue-based registration of an intraoral scan with a CBCT scan can be performed with a high degree of precision.

• Journal of Biomedical Engineering Research
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• v.31 no.2
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• pp.134-140
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• 2010

Readily available high resolution brain MRI scans allow detailed visualization of the brain structures. Researchers have focused on developing methods to quantify shape differences specific to diseased scans. We have developed a novel method to quantify shape information for a specific population based on Multidimensional scaling(MDS). MDS is a well known tool in statistics and here we apply this classical tool to quantify shape change. Distance measures are required in MDS which are computed from pair-wise image registrations of the training set. Registration step establishes spatial correspondence among scans so that they can be compared in the same spatial framework. One benefit of our method is that it is quite robust to errors in registrations. Applying our method to 13 brain MRI showed clear separation between normal and diseased (Cushing's syndrome). Intentionally perturbing the image registration results did not significantly affect the separability of two clusters. We have developed a novel method to quantify shape based on MDS, which is robust to image mis-registration.

• Korean Journal of Computational Design and Engineering
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• v.14 no.2
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• pp.129-136
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• 2009

Generally, curved surfaces of ship hull are deformed by flame bending (line heating), multi-press forming, and die-less forming method. The forming methods generate the required in-plane/bending strain or displacement on the flat plate to make the curved surface. Multi-press forming imposes the forced displacements on the flat plate by controlling the position of each pressing points based upon the shape difference between the unfolded flat plate and the curved object shape. The flat plate has been obtained from the unfolding system that is independent of the ship CAD. Apparently, the curved surface and the unfolded-flat surface are expressed by different coordinate systems. Therefore, one of the issues is to find a registration of the unfolded surface and the curved shape for the purpose of minimum amount of forming works by comparing the two surfaces. This paper presents an efficient algorithm to get an optimized registration of two different surfaces in the multi-press forming of ship hull plate forming. The algorithm is based upon the ICP (Iterative Closest Point) algorithm. The algorithm consists of two iterative procedures including a transformation matrix and the closest points to minimize the distance between the unfolded surface and curved surfaces. Thereby the algorithm allows the minimized forming works in ship-hull forming.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.5
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• pp.652-658
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• 2021

When acquiring a point cloud using a 3D scanner, a registration process of making the acquired data based on each local coordinate into one data with a unified world coordinate system is required. Its process is difficult to obtain a satisfactory result with only one execution, and it is repeated several times to increase the registration precision. The criterion for determining the registration accuracy is an important factor. The previous methods for determining the accuracy of registration have a limitation in that the judgment may be ambiguous in some cases, and different results may be produced each time depending on the characteristics of the point cloud. Therefore, to calculate the accuracy of registration more precisely, I propose a method using the average distance value of the point group for the entire points rather than the corresponding points used in the registration. When this method is used, it is possible to determine the registration accuracy more reliably than the conventional methods.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.177-186
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• 2013

PURPOSES: The purpose of this study theoretically reviews vertical grade deriving process in super high speed environment and compares overseas design criteria with Domestic Standardization also draws suitable vertical grade design criteria of high standard for Domestic Circumstances in Korea. METHODS : By researching domestic vehicle registration status, calculating typical vehicle, using Vissim which is traffic simulation program, Speed-distance curve of the vehicle is derived under each design speed condition. Through Speed-distance curve, estimating critical length of grade and considering critical length of grade, maximum longitudinal incline is proposed. RESULTS : The result of domestic vehicle registration status, the typical vehicle for deriving vertical grade is calculated based on gravity horsepower ratio 200 lb/hp. For calculating critical length of grade, according to change speed of uphill entry, speed-distance curve is derived by using Vissim. Critical length of grade is calculated based on design speed 20 km/h criteria which is point of retardation. Estimated critical length of grade is 808 m and based on this result, maximum longitudinal incline was confirmed in the design speed between 130km/h to 140km/h. CONCLUSIONS: The case of the typical vehicle(truck) which is gravity horsepower ratio 200 lb/hp, maximum longitudinal incline 2% is desirable at the super high speed environment in the design speed between 130km/h to 140km/h.

• Journal of KIISE
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• v.43 no.9
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• pp.1034-1042
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• 2016

Together with machine-learning frameworks, area-based imagery registration techniques can be easily applied to diverse types of image pairs without predefined features and feature descriptors. However, feature detectors are often used to quickly identify candidate image patch pairs, limiting the applicability of these registration techniques. In this paper, we propose a ConvNet (Convolutional Network) "Dart" that provides not only the matching metric between patches, but also information about their distance, which are helpful in reducing the search space of the corresponding patch pairs. In addition, we propose a ConvNet "Fad" to identify the patches that are difficult for Dart to improve the accuracy of registration. These two networks were successfully implemented using Deep Learning with the help of a number of training instances generated from a few registered image pairs, and were successfully applied to solve a simple image registration problem, suggesting that this line of research is promising.