• Journal of Korea Multimedia Society
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• v.22 no.4
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• pp.443-454
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• 2019

In recent years, there has been active research on a recommender system that considers three or more inputs in addition to users and goods, making it a multi-dimensional array, also known as a tensor. The main issue with using tensor is that there are a lot of missing values, making it sparse. In order to solve this, the tensor can be shrunk using the tensor decomposition algorithm into a lower dimensional array called a factor matrix. Then, the tensor is reconstructed by calculating factor matrices to fill original empty cells with predicted values. This is called tensor reconstruction. In this paper, we propose a user-based Top-K recommender system by normalized PARAFAC tensor reconstruction. This method involves factorization of a tensor into factor matrices and reconstructs the tensor again. Before decomposition, the original tensor is normalized based on each dimension to reduce overfitting. Using the real world dataset, this paper shows the processing of a large amount of data and implements a recommender system based on Apache Spark. In addition, this study has confirmed that the recommender performance is improved through normalization of the tensor.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.1
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• pp.89-102
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• 2019

Collagen can be used in building artificial skin replacements for treatment of burns and towards the reconstruction of bone as well as researching cell behavior and cellular interaction. The strength of collagen in connective tissue rests on the characteristics of collagen fibers. 3D confocal imaging of collagen fibers enables the characterization of their spatial distribution as related to their function. However, the image stacks acquired with confocal laser-scanning microscope does not clearly show the collagen architecture in 3D. Therefore, we developed a new method to reconstruct, visualize and characterize collagen fibers from fluorescence confocal images. First, we exploit the tensor voting framework to extract sparse reliable information about collagen structure in a 3D image and therefore denoise and filter the acquired image stack. We then propose to segment the collagen fibers by defining an energy term based on the Hessian matrix. This energy term is minimized by a min cut-max flow algorithm that allows adaptive regularization. We demonstrate the efficacy of our methods by visualizing reconstructed collagen from specific 3D image stack.

• Journal of Korean Neurosurgical Society
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• v.66 no.2
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• pp.183-189
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• 2023

Objective : The facial nerve trace on the ipsilateral side of the vestibular schwannoma was reconstructed by diffusion tensor imaging tractography to identify the adjacent relationship between the facial nerve and the tumor, and to improve the level of intraoperative facial nerve protection. Methods : The clinical data of 30 cases of unilateral vestibular schwannoma who underwent tumor resection via retrosigmoid approach were collected between January 2019 and December 2020. All cases underwent magnetic resonance imaging examination before operation. Diffusion tensor imaging and anatomical images were used to reconstruct the facial nerve track of the affected side, so as to predict the course of the nerve and its adjacent relationship with the tumor, to compare the actual trace of the facial nerve during operation, verify the degree of coincidence, and evaluate the nerve function (House-Brackmann grade) after surgery. Results : The facial nerve of 27 out of 30 cases could be displayed by diffusion tensor imaging tractography, and the tracking rate was 90% (27/30). The intraoperative locations of facial nerve shown in 25 cases were consistent with the preoperative reconstruction results. The coincidence rate was 92.6% (25/27). The facial nerves were located on the anterior middle part of the tumor in 14 cases, anterior upper part in eight cases, anterior lower part in seven cases, and superior polar in one case. Intraoperative facial nerve anatomy was preserved in 30 cases. Among the 30 patients, total resection was performed in 28 cases and subtotal resection in two cases. The facial nerve function was evaluated 2 weeks after operation, and the results showed grade I in 12 cases, grade II in 16 cases and grade III in two cases. Conclusion : Preoperative diffusion tensor imaging tractography can clearly show the trajectory and adjacent position of the facial nerve on the side of vestibular schwannoma, which is beneficial to accurately identify and effectively protect the facial nerve during the operation, and is worthy of clinical application and promotion.

• The Journal of Korean Physical Therapy
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• v.32 no.6
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• pp.388-390
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• 2020

Objectives: The nigrostriatal tract (NST) connect from the substantia nigra pars compacta to the striatum. A few previous studies have reported on the NST in the Parkinson's disease using a proboblistic tractography method. However, no study has been conducted for identification of the NST using streamline DTT technique. In the current study, we used streamline DTI technique to investigate the reconstruction method and characteristics of the NST in normal subjects. Methods: Eleven healthy subjects were recruited in this study. The NST from the substantia nigra of the midbrain and the striatum of basal ganglia was reconstructed using DTI data. Fractional anisotropy, apparent diffusion coefficient (ADC) values and fiber numbers of the NST were measured. Results: In all subjects, the NST between the substantia nigra of the midbrain and the striatum. Mean values for FA, ADC, and tract volume were 0.460, 0.818, and 154.3 in the right NST, and 0.485, 0.818, and 176.3 in the left NST respectively. Conclusions: we reconstructed the NRT from the substantia nigra of the midbrain and the striatum of the basal ganglia using streamline tractography method. We believe that the findings and the proposed streamline reconstruction method of this study would be useful in future researches on the NST of the human brain.

• Archives of Reconstructive Microsurgery
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• v.7 no.2
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• pp.81-87
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• 1998

We have investigated the clinical results of 33 cases of free flap transfer performed for the soft tissue defects of heel and sole. In donor sites, tensor fascia lata flaps were 4, dorsalis pedis flaps were 10, forearm flaps were 9, and latissimus dorsi flaps were 10. The recipient sites were heel in 22 cases, sole in 7 cases, and heel and sole in 4 cases. In these cases, the postoperative complications, morbidity of donor sites, recovery of sensation, and cosmetic results were evaluated in each flap. All the flaps survived successfully. The free flaps provided excellent functional and cosmetic results. The tensor fascia lata flap was more reliable free flap for the reconstruction of heel and sole defects.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1564-1569
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• 2007

This study concerns an advanced NURBS surface reconstruction method, which is based on the NURBS surface model fitting to the unstructured point cloud measured from an arbitrary complex shape. The concept of generating a simple triangular mesh model was introduced to generate a quadrilateral mesh model well-representing the topological characteristics of point cloud. The NURBS surface reconstruction processes required the use of the various methodologies such as QEM algorithm, merging scheme of pair-wise triangular mesh, creation algorithm of $G^1$ continuous tensor product NURBS surface patch, and so on. The effectiveness and reliability of the proposed NURBS surface reconstruction method were validated through the simulation results for the geometrically and topologically complex shapes.

• Journal of Advanced Information Technology and Convergence
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• v.10 no.1
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• pp.25-36
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• 2020

Motivation: Fibers as the extracellular filamentous structures determine the shape of the cytoskeletal structures. Their characterization and reconstruction from a 3D cellular image represent very useful quantitative information at the cellular level. In this paper, we presented a novel automatic method to extract fiber diameter distribution through a pipeline to reconstruct fibers from 3D fluorescence confocal images. The pipeline is composed of four steps: segmentation, skeletonization, template fitting and fiber tracking. Segmentation of fiber is achieved by defining an energy based on tensor voting framework. After skeletonizing segmented fibers, we fit a template for each seed point. Then, the fiber tracking step reconstructs fibers by finding the best match of the next fiber segment from the previous template. Thus, we define a fiber as a set of templates, based on which we calculate a diameter distribution of fibers.

• Archives of Reconstructive Microsurgery
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• v.5 no.1
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• pp.1-15
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• 1996

From Fabuary 1982 to May 1995, 396 patients had undergone reconstructive surgery of the upper and lower limb with microsurgical technique at department of orthopaedic surgery, Yonsei University of Medicine. The results were as follows; 1. Average age at the time of operation was 23.4years(2-64 years), and there were 277 male and 119 female patients. 2. Among 324 patients of soft tissue flap(87 inguinal flap, 132 scapular flap, 38 latissimus dorsi flap, 11 latissimus dorsi and scapular combind flap, 6 gracilis flap, 12 deltoid flap, 3 tensor facia lata flap, 11 dorsalis pedis flap, 6 lateral thigh flap, 12 wrap around flap, 1 lateral arm flap, 5 musculocutaneous flap), 274 cases(85.5%) were succeed. 3. Among 37 patients of vascularized bone graft(18 fibular bone graft, 11 iliac bone graft, 7 toe to finger transplantation,1 vascular pedicle rib graft), 30 cases(80.1%) were succeed. 4. In 26 cases of segmental resection and rotationplasty at lower extremity, 23 cases were succeed. 5. In 7 cases of Tikhoff-Linberg procedure and in 2 case of segmental resection and replantation, all case was succeed. Overall success rate of microscopic reconstructive surgery was 85.6%. In conclusion, microsurgical technigue is valuable for reconstruction of tissue defect or function loss of the limb.

• Investigative Magnetic Resonance Imaging
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• v.11 no.2
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• pp.110-118
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• 2007

Purpose: The objective of this work to construct eigenvalue maps that have information of magnitude of three primary diffusion directions using diffusion tensor images. Materials and Methods: To construct eigenvalue maps, we used a 3.0T MRI scanner. We also compared the Moore-Penrose pseudo-inverse matrix method and the SVD (single value decomposition) method to calculate magnitude of three primary diffusion directions. Eigenvalue maps were constructed by calculating of magnitude of three primary diffusion directions. We did investigate the relationship between eigenvalue maps and fractional anisotropy map. Results: Using Diffusion Tensor Images by diffusion tensor imaging sequence, we did construct eigenvalue maps of three primary diffusion directions. Comparison between eigenvalue maps and Fractional Anisotropy map shows what is difference of Fractional Anisotropy value in brain anatomy. Furthermore, through the simulation of variable eigenvalues, we confirmed changes of Fractional Anisotropy values by variable eigenvalues. And Fractional anisotropy was not determined by magnitude of each primary diffusion direction, but it was determined by combination of each primary diffusion direction. Conclusion: By construction of eigenvalue maps, we can confirm what is the reason of fractional anisotropy variation by measurement the magnitude of three primary diffusion directions on lesion of brain white matter, using eigenvalue maps and fractional anisotropy map.

• Journal of radiological science and technology
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• v.43 no.6
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• pp.475-480
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• 2020

The purpose of this study was to reconstruct diffusion tensor tractography (DTT) using stem of garlic and asparagus for in vitro phantom of diffusion tensor imaging (DTI), and to compare and evaluate the fractional anisotropy (FA) value and the apparent diffusion coefficient (ADC) value to determine whether it can be used as materials for in vitro phantoms. Among various plant fibers such as stem of garlic, palmae, cotton, asparagus, etc., stem of garlic and asparagus, which are considered to be the most suitable for making phantoms, and whose shape is considered to be the most suitable for making phantoms, were selected and tests were conducted. Holes were made in a plastic bucket at an angle of 0°, 30°, 60°, 90°, and 120°, then tubes were inserted. In the tube, asparagus and stem of garlic were inserted as far in as possible, and the inserted tube was inserted into the center of the heat bathed gelatin to harden. We were able to reproduce DTT images in asparagus and stem of garlic. Fiber tissues of asparagus and stem of garlic did not show complete connectivity, but the reconstructed images of DTT showed good connectivity. The FA values of asparagus in the tubes were 0.198 at 0° (straight), 0.207 at 30°, 0.187 at 60°, 0.231 at 90°, and 0.204 at 120°. In addition, the FA values of stem of garlic in the tubes were 0.235 at 0°, 0.236 at 30°, 0.216 at 60°, 0.218 at 90°, and 0.257 at 120°. The ADC values of asparagus in the tubes were 1.545 at 0°, 1.677 at 30°, 1.629 at 60°, 1.535 at 90°, and 1.725 at 120°. In addition, the ADC values of stem of garlic in the tubes were 1.252 at 0°, 1.396 at 30°, 1.698 at 60°, 1.756 at 90°, and 1.466 at 120°. For the best expressed DTT reconstruction image, it showed the longest connectivity in the straight line as we hypothesized. In addition, when comparing the FA values and ADC values of fiber tissues of stem of garlic and asparagus, FA value was generally higher in stem of garlic and ADC value was slightly higher in asparagus.