• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3172-3193
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• 2018

Recently, several studies have shown that linear representation based approaches are very effective and efficient for image classification. One of these linear-representation-based approaches is the Collaborative representation (CR) method. The existing algorithms based on CR have two major problems that degrade their classification performance. First problem arises due to the limited number of available training samples. The large variations, caused by illumintion and expression changes, among query and training samples leads to poor classification performance. Second problem occurs when an image is partially noised (contiguous occlusion), as some part of the given image become corrupt the classification performance also degrades. We aim to extend the collaborative representation framework under limited training samples face recognition problem. Our proposed solution will generate virtual samples and intra-class variations from training data to model the variations effectively between query and training samples. For robust classification, the image patches have been utilized to compute representation to address partial occlusion as it leads to more accurate classification results. The proposed method computes representation based on local regions in the images as opposed to CR, which computes representation based on global solution involving entire images. Furthermore, the proposed solution also integrates the locality structure into CR, using Euclidian distance between the query and training samples. Intuitively, if the query sample can be represented by selecting its nearest neighbours, lie on a same linear subspace then the resulting representation will be more discriminate and accurately classify the query sample. Hence our proposed framework model the limited sample face recognition problem into sufficient training samples problem using virtual samples and intra-class variations, generated from training samples that will result in improved classification accuracy as evident from experimental results. Moreover, it compute representation based on local image patches for robust classification and is expected to greatly increase the classification performance for face recognition task.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.46-52
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• 2017

Provisional restoration plays an important role in the process of restoration with fixed partial denture by providing protection and restoring function and esthetics of abutment tooth. This is especially true in patients requiring use of provisional prosthesis for a long term. However, such situations may lead to higher possibility of provisional prosthesis fracture, and if expected so, reinforcement of provisional prosthesis should be considered. In this article, a patient requiring prosthetic treatment with increase of vertical dimension of occlusion was introduced. Due to increased vertical dimension of occlusion, the provisional restoration was expected to withstand relatively larger amount of load during a relatively long observation period. In order to minimize possible occurrence of fracture, reinforcement of the provisional restoration was sought by insertion of cast-metal framework and by using bis-acryl resin. The reinforced provisional restoration showed satisfactory results during the observation period of 4 months.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.437-447
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• 2011

In patients who used removable partial dentures for a long period of time, gradual alveolar bone resorption occurs in edentulous area. However, in residual teeth area, alveolar bone is maintained sound. This causes an imbalance in intermaxillary distance between a maxillae and a mandible which is intensified due to expansion in vertical and horizontal bone amount difference between the two area as time passes. As the result, this shows a substantial difference in vertical position according to the period of teeth loss even after residual teeth loss. As in this situation, a patient with bilaterally and anterio-posteriorly different intermaxillary distance, various prosthodontic problems can be caused in fixed implant prosthodontics and implant overdenture. This study shows a case in which implant-supported removable partial denture was fabricated considering residual alveolar bone height after teeth loss in a patient who had been using a distal extension removable partial denture for a long period of time. In anterior area with short intermaxillary distance, fixed prosthodontics were fabricated with implant placement and in posterior area with long intermaxillary distance, a removable partial denture was fabricated. Finally, a small number of implants were placed without additional surgery and economical and comfortable treatment results were shown.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.3
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• pp.186-194
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• 2015

Purpose: To evaluate the effects of implant location and length on stress distribution and displacement in osseointegrated-implants that were associated with mandibular distal extension removable partial dentures (DERPD). Materials and Methods: A sagittally cut model with the #33, #34 teeth and a removable partial denture of the left mandible was used. Seven models were designed with NX 9.0. Models A, B, C had implants with lengths of 11, 6, 4 mm, respectively, under the denture base of the #37 artificial tooth. Models D, E, F had implants with lengths of 11, 6, 4 mm, respectively, under the denture base of the #36 artificial tooth. Model G did not have any implants. Axial force (250 N) was loaded on #36 central fossa. The finite element analysis was performed with MSC Nastran. Von Mises stress maps were plotted to visualize the results. Results: The models of #37 implant placement showed much lower stress concentration on the surrounding bone of the implant compared with #36. The #36 implant position tended to reduce displacement more than #37. Conclusion: When an IARPD is designed, the distal positioning of implant placement has more advantages in the edentulous bone of DERPD on the prognosis of short implants and the stress distribution of edentulous alveolar bone. Using implants with longer lengths are important for stress distribution. However, Additional studies are necessary of the effects of length on implant survival.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.1
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• pp.67-78
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• 1996

The purpose of this paper is object recognition even in the presence of occlusion by using generalized Hough transform(GHT). The GHT can be considered as a kind of model based object recognition algorithm and is executed in the following two stages. The first stage is to store the information of the model in the form of R-table (Reference table). The next stage is to identify the existence of the objects in the image by using the R-table. The improved GHT method is proposed for the practical vision system. First, in constructing the R-table, we extracted the partial arc from the portion of the whole object boundary, and this partial arc can be used for constructing the R-table. Also, clustering algorithm is employed for compensating an error arised by digitizing an object image. Second, an efficient method is introduced to avoid Ballard's use of 4-D array which is necessary for estimating position, orientation and scale change of an object. Only 2-D array is enough for recognizing an object. Especially, scale token method is introduced for calculating the scale change which is easily affected by camera zoom. The results of our test show that the improved hierarchical GHT method operates stably in the realistic vision situation, even in the case of object occlusion.

• Clinical and Experimental Pediatrics
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• v.45 no.11
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• pp.1397-1402
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• 2002

Purpose : One of the major complication of arterial catheterization is the thrombosis of the iliac or femoral arteries. Tissue loss following femoral artery catheterization is rare. However longterm sequelae such as impaired limb growth and future impairment of vascular access, are also important in pediatric cardiac patients. But standard methods to treat thrombotic complication of arterial catheterization in infants and children is not established. The present study was performed to assess the efficacy of intraarterial catheter-directed urokinase infusion in infants and children with limb ischemia due to arterial thrombosis after cardiac catheterization. Methods : From January 1994 to August 2002, 12 patients with thrombotic femoral artery occlusion after arterial catheterization were treated with catheter-directed urokinase infusion in Dong-A University Hospital. Retrospective analysis of the medical records and angiograms was conducted. Results : The incidence of femoral artery thrombosis after retrograde arterial catheterization, which had not responded to systemic infusion of heparin and/or urokinase, was 2.8 percent. The doses of urokinase were 1,000-4,400 unit/kg/hr and duration of infusion was $50.6{\pm}29.2$ hours(18-110 hours). Clot resolution was complete in all patients who started to receive the intraarterial urokinase infusion within four days after catheterization. Only partial thrombolysis was seen in two patients who were treated with intraarterial urokinase on the 12th and 19th days after thrombus formation. Balloon angioplasty was done for these two patients with partial success. Bleeding complications were seen in two cases. Conclusion : Early use of catheter-directed intraarterial infusion of urokinase is safe and effective in thrombolysis of femoral artery occlusion after cardiac catheterization in infants and children.

• Journal of Korean Neurosurgical Society
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• v.64 no.6
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• pp.891-900
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• 2021

Objective : Vertebral artery dissecting aneurysm (VADA) is a very rare subtype of intracranial aneurysms; when ruptured, it is associated with significantly high rates of morbidity and mortality. Despite several discussions and debates, the optimal treatment for VADA has not yet been established. In the last 10 years, flow diverter devices (FDD) have emerged as a challenging and new treatment method, and various clinical and radiological results have been reported about their safety and effectiveness. The aim of our study was to evaluate the clinical and radiological results with the use of FDD in the treatment of unruptured VADA. Methods : We retrospectively evaluated the data of all patients with unruptured VADA treated with FDD between January 2018 and February 2021 at our hybrid operating room. Nine patients with unruptured VADA, deemed hemodynamically unstable, were treated with FDD. Among other parameters, the technical feasibility of the procedure, procedure-related complications, angiographic results, and clinical outcomes were evaluated. Results : Successful FDD deployment was achieved in all cases, and the immediate follow-up angiography showed intra-aneurysmal contrast stasis with parent artery preservation. A temporary episode of facial numbness and palsy was noted in one patient; however, the symptoms had completely disappeared when followed up at the outpatient clinic 2 weeks after the procedure. The 3-6 months follow-up angiography (n=9) demonstrated complete/near-complete obliteration of the aneurysm in seven patients, and partial obliteration and segmental occlusion in one patient each. In the patient who achieved only partial obliteration, there was a sac 13 mm in size, and there was no change in the 1-year follow-up angiography. In the patient with segmental occlusion, the cause could not be determined. The clinical outcome was modified Rankin Scale 0 in all patients. Conclusion : Our preliminary study using FDD to treat hemodynamically unstable unruptured VADA showed that FDD is safe and effective. Our study has limitations in that the number of cases is small, and it is not a prospective study. However, we believe that the study contributes to evidence regarding the safety and effectiveness of FDD in the treatment of unruptured VADA.

• Journal of Korean Neurosurgical Society
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• v.38 no.2
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• pp.89-95
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• 2005

Objective : The purpose of this study is to analyze aneurysm morphology and define limitations and feasibility in endovascular Gugliemi detachable coil[GDC] embolization for anterior communicating artery [ACoA] aneurysms. Methods : From January 2000 through October 2003, 123patients were treated with endovascular coil embolization for ACoA aneurysms. There were 75women and 48men, with a mean age of 63years. All ruptured aneurysms were treated within 15days of rupture. Aneurysm morphology was classified according to neck size and projection of aneurysm dome as follows-A : neck of aneurysm <4mm & anterior projection, B : neck of aneurysm [4mm & anterior projection, C : neck of aneurysm<4mm & posterior [superior] projection, D : neck of aneurysm [4mm & posterior [superior] projection, E : neck of aneurysm<4mm & inferior projection, and F : neck of aneurysm [4mm & inferior projection. Endovascular procedures were categorized as either "successful" or "unsuccessful". Clinical follow-up was estimated at discharge and at 6months, post treatment results were classified according to Glasgow Outcome Scale[GOS]. Results : Successful embolization for ACoA was performed in 86patients of 123patients [69.9%]. Complete or near complete aneurysm occlusion was observed in 102patients [82.9%]; a neck remnant was observed in 6patients [4.9%]; partial embolization was done in 3patients [2.4%]; and embolization was attempted in 12patients [9.8%]. Among 55patients with follow-up angiographic results, 18patients [32.7%] were defined as recanalization of the aneurysm sac. Morphological analysis demonstrated that anterior projecting aneurysms and morphological classifications [morphological classifications worsens [A - D] chances of successful coil occlusion significantly decrease] were major factors in successful embolization, and, inferiorly projecting and wide neck [${\ge}4mm$] aneurysms are highly related to recanalization of aneurysms. Conclusion : Endovascular coil embolization of ACoA aneurysms shows good outcome in our study. Nevertheless, there is a limitation in the endovascular approach to ACoA, even though advanced modern techniques evolve rapidly. Compensatory surgical approach with the endovascular approach is required for successful treatment of ACoA aneurysms.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.1
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• pp.54-63
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• 2024

The long-term use of an implant overdenture shows problems, such as wear of attachment, concentrated occlusal forces on the anterior teeth, fracture of artificial teeth and rotation of denture. By transitioning to an Implant-assisted removable partial denture (IARPD) using additional implant placement, the problems can be solved. In this case report, a transition was made from implant overdenture to IARPD utilizing surveyed crowns to distribute occlusal forces concentrated on anterior teeth and to prevent denture rotation in a skeletal Class III patient. Design of definitive prosthesis with appropriate function and aesthetics was determined through several stages of provisional restorations. In this case, appropriate posterior occlusion and maintenance of peri-implant bone level of definitive prosthesis were observed.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.45-49
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• 2015

In this clinical report, a simple and convenient conversion of a fractured metal-ceramic surveyed crown into a complete contour zirconia surveyed crown by using computer-aided design and computer-aided manufacturing technology for an existing partial removable dental prosthesis is described. The duplication of the original contours, morphology, and the rest seat of the existing metal-ceramic surveyed crown, into a complete contour zirconia surveyed crown under anticancer treatments were reported.