• Earthquakes and Structures
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• v.1 no.3
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• pp.289-306
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• 2010

A gradient-based evolutionary optimization methodology is presented for finding the optimal design of viscous dampers to minimize an objective function defined for a linear multi-storey structure. The maximum value along height of the transfer function amplitudes for the interstorey drifts is taken as the objective function. Since the ground motion includes various uncertainties, the optimal damper placement may be different depending on the ground motion used for design. Furthermore, the transfer function treated as the objective function depends on the properties of structural parameters and added dampers. This implies that a more robust damper design is desired. A reliable and robust damping design system against any unpredictable ground motions can be provided by minimizing the maximum transfer function. Such design system is proposed in this paper.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.7
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• pp.3329-3350
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• 2017

Installing caching and computing facilities in mobile edge networks is a promising solution to cope with the challenging capacity and delay requirements imposed on future mobile communication systems. The problem of optimal facility placement in mobile edge networks has not been fully studied in the literature. This is a non-trivial problem because the mobile edge network has a unidirectional topology, making existing solutions inapplicable. This paper considers the problem of optimal placement of a fixed number of facilities in a mobile edge network with an arbitrary tree topology and an arbitrary demand distribution. A low-complexity sequential algorithm is proposed and proved to be convergent and optimal in some cases. The complexity of the algorithm is shown to be $O(H^2{\gamma})$, where H is the height of the tree and ${\gamma}$ is the number of facilities. Simulation results confirm that the proposed algorithm is effective in producing near-optimal solutions.

• Journal of Korean Dental Science
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• v.4 no.2
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• pp.59-66
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• 2011

Purpose: This research sought to determine the resorption rate of bone grafted to the maxillary sinus according to the grafted material's type, patient's age, systemic disease, implant size, site of implant placement, and residual ridge height. Materials and Methods: This research targeted 24 patients who had immediate Osstem$^{(R)}$ implant (US Plus$^{(R)}$) placement after bone graft. The panorama was taken before the surgery, after the surgery, and 6 months after the surgery. Vertical height change and resorption rate of the grafted bone were measured with the same X-rays and compared. The influence of the following factors on the grafted bone material's resorption rate was evaluated: grafted material type, patient's age, systemic disease, implant size, site of implant placement, and residual ridge height. Results: Patients in their 40s had $34.0{\pm}21.1%$ resorption rate, which was significantly higher compared to the other age groups (P<0.05). There was no significant relationship between systemic disease and grafted bone resorption. There was no significant relationship between implant size (diameter, length) and grafted bone resorption. There was no significant relationship between the site of implant placement and grafted bone resorption. The ramal bone-grafted site was significantly more resorbed than the ramal bone/Bio-Oss$^{(R)}$-grafted site, maxillary tuberosity bone/Bio-Oss$^{(R)}$-grafted site, and ramal bone/maxillary tuberosity bone/Bio-Oss$^{(R)}$-grafted site (P<0.05). There was no significant difference in the grafted bone resorption rate in the sinus between more than 4 mm and less than 4 mm residual ridge heights. After an average of 6 months, a second surgery was done; given an average follow-up of 1.9 years, the success rate and survival rate of the implant were 96.9% and 98.4%, respectively. Conclusion: These results indicate that the bone resorption rate of grafted bone among patients in their 40s is higher compared to patients in their 50s and over, and that only autogenous bone (ramus) shows higher resorption rate than the mixed graft of autogenous bone and xenogenous graft (Bio-oss) after maxillary sinus graft.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.5
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• pp.495-499
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• 2008

For the successful placement of dental implants, adequate alveolar bone height and width are required. Alveolar distraction osteogenesis is an effective method that resolves insufficient alveolar bone height for dental implant placement, and thus has been clinically applied with satisfactory results. But, minor and major problems may occur during the treatment. In the following report, we studied for such problematic cases. The problems are as follows: 1) sharp edges of the transport segment, 2) infection, 3) soft tissue dehiscence, 4) limitation of distraction, 5) numbness, 6) insufficient bone formation. But, most of them were answered by simple solutions and did not jeopardize the final outcomes. Distraction osteogenesis can be considered a safe and predictable procedure for lengthening the alveolar bone.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.481-484
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• 2008

The temperature crack of concrete structure is caused by the phenomenon which the concrete volume is restricted in the inside or outside part due th the temperature variations induced by the hydration heat of cement. And mass concrete structures are weak in temperature crack. Seongdeok multi-purpose dam is gravity dam which is being constructed in Cheongsong-gun, Gyeonsangbuk-do. Upstream cofferdam was constructed to examine the temperature crack due to hydration heat and to decide the height of placement. Therefore this study performed the hydration heat analysis of Seongdeok upstream coffer dam to analyze the hydration heat according to different height of placement and to compare with measured results.

• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.4
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• pp.307-312
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• 2017

Background: The aim of this study was to estimate the optimal depth of nasotracheal tube placement. Methods: We enrolled 110 patients scheduled to undergo oral and maxillofacial surgery, requiring nasotracheal intubation. After intubation, the depth of tube insertion was measured. The neck circumference and distances from nares to tragus, tragus to angle of the mandible, and angle of the mandible to sternal notch were measured. To estimate optimal tube depth, correlation and regression analyses were performed using clinical and anthropometric parameters. Results: The mean tube depth was $28.9{\pm}1.3cm$ in men (n = 62), and $26.6{\pm}1.5cm$ in women (n = 48). Tube depth significantly correlated with height (r = 0.735, P < 0.001). Distances from nares to tragus, tragus to angle of the mandible, and angle of the mandible to sternal notch correlated with depth of the endotracheal tube (r = 0.363, r = 0.362, and r = 0.546, P < 0.05). The tube depth also correlated with the sum of these distances (r = 0.646, P < 0.001). We devised the following formula for estimating tube depth: $19.856+0.267{\times}sum$ of the three distances ($R^2=0.432$, P < 0.001). Conclusions: The optimal tube depth for nasotracheally intubated adult patients correlated with height and sum of the distances from nares to tragus, tragus to angle of the mandible, and angle of the mandible to sternal notch. The proposed equation would be a useful guide to determine optimal nasotracheal tube placement.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.3
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• pp.241-248
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• 2011

Purpose: The aim of this study was to present the clinical results of maxillary sinus augmentation implants and to evaluate the effects of various factors on the implant survival rate. Methods: In a total of 112 patients, 293 implants after sinus augmentation were performed. The total survival rate and the influence of the following factors on implant survival were evaluated; patient characteristics (sex, age, smoking, general disease), graft material, implant surface, implant installation stage, site of implant placement, length and width of implant, closure method for osseous window, residual alveolar bone height. Results: 1. Age ranged from 16 to 70 yr, with a mean of 45.7 yr. 2. Cumulative survival rate for the 293 implants with the maxillary sinus augmentation procedure was 94.9%. 3. Simultaneous implant installation was performed in 122 patients and delayed implant installation was performed in 117 implants. The average healing period after sinus elevation was 7.3 months for delayed implant installation and this procedure had a significantly higher survival rate. 4. There were no significant differences in sex, age, smoking, general disease, site of implant placement, length and width of implant, residual alveolar bone height and the survival rate. 5. RBM (Resorbable Blasting Media) implant surface and allograft groups had significantly lower survival rates. Conclusion: These data suggest that maxillary sinus augmentation may give more predictable results for autogenous bone grafts and delayed implant placement.

• Journal of Periodontal and Implant Science
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• v.54 no.2
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• pp.108-121
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• 2024

Purpose: The aim of this study was to compare changes in soft and hard tissue and the histologic composition following early implant placement in sites with alveolar ridge preservation or spontaneous healing (SH), as well as implant performance up to 1 year after crown insertion. Methods: Thirty-five patients with either intact buccal bone plates or dehiscence of up to 50% following single-tooth extraction of incisors, canines, or premolars were included in the study. They were randomly assigned to undergo one of three procedures: deproteinized bovine bone mineral with 10% collagen (DBBM-C) covered by a collagen matrix (DBBM-C/CM), DBBM-C alone, or SH. At 8 weeks, implant placement was carried out, and cone-beam computed tomography scans and impressions were obtained for profilometric analysis. Patients were followed up after the final crown insertion and again at 1 year post-procedure. Results: Within the first 8 weeks following tooth extraction, the median height of the buccal soft tissue contour changed by -2.11 mm for the DBBM-C/CM group, -1.62 mm for the DBBM-C group, and -1.93 mm for the SH group. The corresponding height of the buccal mineralized tissue changed by -0.27 mm for the DBBM-C/CM group, -2.73 mm for the DBBM-C group, and -1.48 mm for the SH group. The median contour changes between crown insertion and 1 year were -0.19 mm in the DBBM-C/CM group, -0.09 mm in the DBBM-C group, and -0.29 mm in the SH group. Conclusions: Major vertical and horizontal ridge contour changes occurred, irrespective of the treatment modality, up to 8 weeks following tooth extraction. The DBBM-C/CM preserved more mineralized tissue throughout this period, despite a substantial reduction in the overall contour. All 3 protocols led to stable tissues for up to 1 year.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.5
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• pp.331-336
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• 2013

Maxillary sinus membrane elevation and bone graft have been performed routinely in alveolar bone with insufficient residual bone height. There are a number of causes for development of maxillary sinusitis after these procedures. When maxillary sinusitis is caused by sinus membrane elevation, bone graft, and implant placement, various treatment such as medication, incision and drainage (I&D), implant removal, and the Caldwell-Luc procedure can be considered. Removal of an implant or the Caldwell-Luc procedure can be harmful if inflammation is not present in the oral cavity and survival of grafted bone and implant osseointegration can be expected despite the presence of maxillary sinusitis. In this case, functional endoscopic sinus surgery, which was often used in the otorhinolaryngology department, was performed without removal of the implant for a patient with maxillary sinusitis after one month following implant placement. Thus, we report on this case with a review of the literature.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.3
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• pp.117-122
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• 2014

Objectives: The purpose of this study was to evaluate the sinus bone graft resorption over 3 years after two-stage implant placement. Materials and Methods: The subjects for this study included 30 patients whose maxillary posterior ridges were too atrophic for implants. Bone-added osteotome sinus floor elevation was used in 15 maxillary sinuses, while the bone graft by lateral approach technique was used in 25 maxillary sinuses. The height from the top of the fixture to the sinus floor was estimated immediately after implant placement and the follow-up period was over 3 years. The surgery was classified with two groups: sinus bone grafting with and without autogenous bone. All implants were placed simultaneously. Results: The mean vertical bone loss was $3.15{\pm}2.95mm$. The survival rate of implants was 94.7%. Conclusion: The amount of bone resorption was not significantly associated with the surgical methods, the type of bone graft materials used, or sinus perforation during surgery.