• Journal of Cardiovascular Imaging
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• v.31 no.3
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• pp.135-141
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• 2023

BACKGROUND: Global longitudinal strain (GLS) is an accurate and reproducible parameter of left ventricular (LV) systolic function which has shown meaningful prognostic value. Fast, user-friendly, and accurate tools are required for its widespread implementation. We aim to compare a novel web-based tool with two established algorithms for strain analysis and test its reproducibility. METHODS: Thirty echocardiographic datasets with focused LV acquisitions were analyzed using three different semi-automated endocardial GLS algorithms by two readers. Analyses were repeated by one reader for the purpose of intra-observer variability. CAAS Qardia (Pie Medical Imaging) was compared with 2DCPA and AutoLV (TomTec). RESULTS: Mean GLS values were -15.0 ± 3.5% from Qardia, -15.3 ± 4.0% from 2DCPA, and -15.2 ± 3.8% from AutoLV. Mean GLS between Qardia and 2DCPA were not statistically different (p = 0.359), with a bias of -0.3%, limits of agreement (LOA) of 3.7%, and an intraclass correlation coefficient (ICC) of 0.88. Mean GLS between Qardia and AutoLV were not statistically different (p = 0.637), with a bias of -0.2%, LOA of 3.4%, and an ICC of 0.89. The coefficient of variation (CV) for intra-observer variability was 4.4% for Qardia, 8.4% 2DCPA, and 7.7% AutoLV. The CV for inter-observer variability was 4.5%, 8.1%, and 8.0%, respectively. CONCLUSIONS: In echocardiographic datasets of good image quality analyzed at an independent core laboratory using a standardized annotation method, a novel web-based tool for GLS analysis showed consistent results when compared with two algorithms of an established platform. Moreover, inter- and intra-observer reproducibility results were excellent.

• ETRI Journal
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• v.26 no.6
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• pp.641-646
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• 2004

As the use of signatures for identification purposes is pervasive in society and has a long history in business, dynamic signature verification (DSV) could be an answer to authenticating a document signed electronically and establishing the identity of that document in a dispute. DSV has the advantage in that traits of the signature can be collected on a digitizer. The research question of this paper is to understand how the individual variables vary across devices. In applied applications, this is important because if the signature variables change across the digitizers this will impact performance and the ability to use those variable. Understanding which traits are consistent across devices will aid dynamic signature algorithm designers to create more robust algorithms.

• Journal of Computing Science and Engineering
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• v.2 no.1
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• pp.98-108
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• 2008

Terrain reconstruction from images is an ill-posed, yet commonly desired Structure from Motion task when compositing visual effects into live-action photography. These surfaces are required for choreography of a scene, casting physically accurate shadows of CG elements, and occlusions. We present a novel framework for generating the geometry of landscapes from extremely noisy point cloud datasets obtained via limited resolution techniques, particularly optical flow based vision algorithms applied to live-action video plates. Our contribution is a new statistical approach to remove erroneous tracks ('outliers') by employing a unique combination of well established techniques-including Gaussian Mixture Models (GMMs) for robust parameter estimation and Radial Basis Functions (REFs) for scattered data interpolation-to exploit the natural constraints of this problem. Our algorithm offsets the tremendously laborious task of modeling these landscapes by hand, automatically generating a visually consistent, camera position dependent, thin-shell surface mesh within seconds for a typical tracking shot.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.611-614
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• 2002

In this paper, a novel error concealment, algorithm is proposed for the MPEG-4 video decoding. Apart from existing algorithms which fail to exhibit stable performance over various video sequences and error patterns, the proposed algorithm adopts a new hybrid scheme, which can achieve a consistent performance with reduced computational complexity. This algorithm is implemented on the basis of the MPEG-4 decoder, and the experimental results demonstrate that the new approach provides acceptable performance both subjectively and objectively at various bit error rates and video sequences.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.685-690
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• 1998

This paper presents an explanation regarding on-line identification of a fuzzy system. The fuzzy system to be identified is assumed to be in the type of singletion consequent parts and be represented by a linear combination of fuzzy basis function (FBF's). For on-line identification, squared-cosine (SCOS) fuzzy basis function is introduced to reduce the number of parameters to be identified and make the system consistent and differentiable. Then the parameters of the fuzzy system are identified on-line by the gradient search method. Finally, a computer simulation is performed to illustrate the validity of the suggested algorithms.

• Journal of Korea Multimedia Society
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• v.19 no.1
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• pp.22-29
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• 2016

Hidden Markov Model is one of the most successful and popular tools for modeling real world sequential data. Real world signals come in a variety of shapes and variabilities, among which temporal and spectral ones are the prime targets that the HMM aims at. A new problem that is gaining increasing attention is characterizing missing observations in incomplete data sequences. They are incomplete in that there are holes or omitted measurements. The standard HMM algorithms have been developed for complete data with a measurements at each regular point in time. This paper presents a modified algorithm for a discrete HMM that allows substantial amount of omissions in the input sequence. Basically it is a variant of Baum-Welch which explicitly considers the case of isolated or a number of omissions in succession. The algorithm has been tested on online handwriting samples expressed in direction codes. An extensive set of experiments show that the HMM so modeled are highly flexible showing a consistent and robust performance regardless of the amount of omissions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.438-445
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• 2006

Due to the complicated character of the hemming process for automobile panels, it is very difficult to set up a consistent and reliable die design guide rule that does not require subtle decision of experienced experts during design stage and multiple trials during hemming die making. In this paper an automatic die design system of hemming units is pursued by presenting some algorithms, in which geometric data and constraints of the hemming units were converted to formula. two kinds of hemming units, 2-link type and 4-link type, were selected as examples and the geometries and kinematics of all parts were analyzed to build the design algorithm.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.167-175
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• 1998

A mathematical formulation is presented to model anisotropy from the deformation textures developed in a forming process. In this work, a micro-mechanical-based polycrystalline analysis is implemented into a consistent finite element method for the anisotropic, viscoplastic deformation of polycrystalline metals. As suggested by Taylor, the deformation of each grain in an aggregate is assumed to be same as the macroscopic deformation of an aggregate or a macro-continuum point. Algorithms are developed to represent the plastic anisotropy, such as the anisotropic yield surface and R-value, from the predicted deformation texture. As applications, the evolution of texture in rolling, upsetting and drawing/extrusion processes are simulated and the corresponding changes of mechanical properties such as yield surface and R-value are predicted.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.5
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• pp.250-258
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• 2003

In this paper, an explanation regarding on-line identification of a fuzzy system is presented. The fuzzy system to be identified is assumed to be in the type of singleton consequent parts and be represented by a linear combination of fuzzy basis functions. For on-line identification, squared-cosine membership function is introduced to reduce the number of parameters to be identified and make the system consistent and differentiable. Then the parameters of the fuzzy system are identified on-line by the gradient search method and Extended Kalman Filter. Finally, a computer simulation is peformed to illustrate the validity of the suggested algorithms.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.268-269
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• 2015

National Maritime PNT Office is operating 17 DGPS reference sites. Considering the relatively small size of South Korea, however, we thought that it is maintaining too many stations. For this reason, new algorithms were developed to effectively generate Pseudo-Range Corrections for the purpose of providing consistent DGPS accuracies throughout the country even with a minimum number of stations.