• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.422-430
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• 1998

This paper presents the results of a major parametric study on the collapse cause of the Sungsoo Grand Bridge, a Gerber-type continuous truss bridge, which had collapsed just at the 15th year since opening to traffic. Among the various collapse causes such as poor design, poor welding, poor maintenance, and heavy traffic loads, this study focuses on the collapse cause assessment incorporating the effects of braket and H-beam members right below the expansion joint of the suspended truss. A local FEM analysis using fine shell elements is carrided out for the more precise estimation of stress range of the vertical pin-connected hanger whose fatigue fracture triggered the collapse of the bridge. Both the conventional S-N approach and the Ang-Munse's fatigue reliability method are used for the evaluation of the fatigue life and fatigue failure probability for the assessment based on all the available results of various field and labolatory tests. From these observations, It may be affirmatively stated that the effects of bracket and H-beam members accelerated the fatigue failure, and thus should be regarded as one of major causes that triggered the bridge collapse

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.102-106
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• 2009

STATEMENT OF PROBLEM. Screw loosening has been a common complication and still reported frequently. PURPOSE. The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS. Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly mounted in liquid unsaturated poly-esther with dental surveyor. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and weight loss were measured. Mann-Whitney test with SPSS statistical software for Window was applied to analyze the measurement of weight loss. RESULTS. TiN-coated abutment screws of Osstem and 3i showed lesser loss of weight than non-coated those of Osstem and 3i (P < .05, Mann-Whitney test). CONCLUSION. Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.329-338
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• 2007

Purpose. The aim of this study is to evaluate the effect of TiN coating of abutment screw on the unscrewing torque. Material and methods. Titanium and Gold-Tite abutment screws were classified into two groups, Group A and C respectively, as control groups. Titanium abutment screws with TiN coatings were also classified into two groups, Group B and D, as experimental ones. Group A and B were tightened to 20 Ncm input torque, and Group C and D were tightened to 32 Ncm torque. Detorque values were measured with digital torque gauge during repeated closing and opening experiment. Results. Abutment screws with TiN coating (Group B and D) showed statistically significant higher mean detorque values than those of Group A and C. Discussion. Physical properties of TiN coating, such as low friction coefficient, high hardness and wear resistance, might contribute to higher detorque values. Conclusion. It is suggested that TiN coating of abutment screw help to reduce the risk of screw loosening and improve the stability of screw joint.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.500-505
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• 2007

Current humanoid robot technology has a problem of lacking opened methodology about mechanisms of analysis, design, implementation, and integration for robot development but is focused only on manufacture robot and implementation of technology. In this paper, to overcome problems of humanoid robots that have been shown since and for construction of new structure which satisfy the concept of opening, networking, and modularization that is the development direction of future robot, we proposed morphological and neurological model of human arm and design method of humanoid robot arm based on the each joint design and kinematics model.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.407-417
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• 2023

Precast assembled bridge piers with hybrid connection (PASP) use both tendons and socket connections. To study the seismic performance of PASP, a full-scale in-situ test was performed based on an actual bridge project. The elastic-plastic fiber model of PASP was established using finite element software, and numerical analyses were performed to study the influence of prestress degree and socket depth on the PASP seismic performance. The results show that the typical failure mode of PASP under horizontal load is bending failure dominated by concrete cracking at the joint between the column and cushion cap. The cracking of the pier concrete and opening of joints depend on the prestress degree and socket depth. The prestressing tendons and socket connection can provide enough ductility, strength, restoration capability, and bending strength under small horizontal displacements. Although the bearing capacity and post yield stiffness of the pier can be improved to some extent by increasing the prestressing force, ductility is reduced, and residual deformation is increased. Overall, there are reasonable minimum socket depths to ensure the reliability of the socket connection.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.18 no.2
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• pp.31-42
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• 2023

Objectives This study aimed to conduct a systematic review evaluating the effectiveness of muscle energy technique(MET) in temporomandibular joint disorders (TMD). Methods Searches were conducted in 11 electronic databases until October 2023. Randomized controlled trials(RCT) comparing the effect of MET for TMD were included. All studies were evaluated using the Cochrane Risk of Bias tool. Results Nine documents that fulfilled all the criteria were obtained for analysis. All studies showed some concerns in high risk of bias, but showed a significant improvement in pain and maximum mouth opening compared to baseline of MET or control group. MET was not better than extracorporeal shock wave therapy or myofascial release in some outcomes. Conclusions MET seems to be an effective treatment for TMD in some regards, however, can be considered as an adjunct therapy which has weak evidence. Further studies are required due to the inconclusive data and poor homogeneity found in this review.

• Korea Trade Review
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• v.46 no.6
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• pp.39-54
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• 2021

This study comprehensively reviews the research conducted until recently in order to derive realistic alternatives in consideration of local industries. The case analysis was performed on a competitive port of similar size, and strategies and revitalization measures were suggested in consideration of the conditions of Gunsan Port. Literature review focused on papers and major reports. The case of similar size were analyzed for Daesan port, Boryeong port, and Mokpo port. In order to find strategies to revitalize the regional port logistics industry behind Gunsan Port, the recent opportunities and threat factors of Gunsan Port were derived. In order to foster the regional port logistics industry with Gunsan Port as its main base, this study proposes a three-step development strategy. It is necessary to increase the effectiveness of the public-private joint port sales and maintain the incentive system, but use it as a means to strengthen the competitiveness of Gunsan Port. Since the possibility of opening various routes is not high due to the conditions of Gunsan Port, various business models can be devised to link the currently opened routes. Start-up in the logistics field can stand out if they provide predictive data or provide consulting services by securing and analyzing logistics data, not directly providing logistics services.

• Journal of Oral Medicine and Pain
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• v.33 no.2
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• pp.195-204
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• 2008

Osteoarthritis is caused by joint degeneration, a process that includes progressive loss of articular cartilage accompanied by attempted repair of articular cartilage, remodeling and sclerosis of subchondral bone, and osteophyte formation. The most common causative factor that either causes or contributes to osteoarthritis is overloading of the articular structures of the joint. The diagnosis of temporomandibular joint(TMJ) osteoarthritis is based on the patient's history and clinical findings such as limited mandibular opening, crepitation and tenderness to palpation on TMJ. The diagnosis is usually confirmed by TMJ radiographs, which will reveal evidence of structural changes in the subarticular bone of the condyle or fossa. Plain radiography techniques such as panoramic, transcranial, transpharyngeal views can be used in most dental offices for evaluation of the TMJs. However, plain radiographs are often limited due to overlapping and distortion of anatomical structures. The aim of this study was to compare the clinical examination and panoramic view with computed tomography for diagnosis of temporomandibular degenerative joint disease, and to compare the findings of condylar bony changes through panoramic radiography with that of computed tomography, hence, to confirm the limitations of clinical and panoramic radiography, and the validity of the computed tomography for diagnosis of temporomandibular degenerative joint disease. The pathophysiology of the TMJ osteoarthritis remains poorly understood, and current treatments are based more on speculation than science, and symptomatic treatments often fail to provide satisfactory pain relief. For diagnosis of TMJ osteoarthritis, clinical examination and radiographic examination for confirmation of the bony changes are essential, and computed tomography are clearly superior to plain radiographs for their limitations.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.5
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• pp.409-416
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• 2005

Purpose of study: The temporomandibular joint (TMJ) occupies a key functional role in mastication and contributes to normal deglutition, speech as well as cosmesis. When a large amount of mandible including the condyle head is resected, it is very difficult to reconstruct it as a functional unit. In this retrospective study, we present the functional, radiographic and cosmetic results of reconstructed temporomandibular joint using free fibular flap. Patients and Methods: Total 12 patients (M:F = 6:6) who underwent condylar reconstruction with the fibular flap were interviewed and examined by radiographs and Bio-PAK$^{(R)}$. Mean follow up periods was $47.7{\pm}20.0$ months and the average age was $38.7{\pm}15.3$ years. Remodeling of condyle and function of TMJ were evaluated and facial contour was judged subjectively. Results: All flaps were viable and no immediate postoperative complication had happened. One patient showed decreased mouth opening, so interpositional gap arthroplasty was performed. The resorption rates of reconstructed fibular were minimal and the condyle heads were changed into domeshaped neocondyle after 2 years. All patients had normal diet and no speech difficulty was reported. Nine patients were satisfied with their facial contour but three patients complained about the depression of cheek. Conclusion: The reconstruction of TMJ with free fibular flap was reliable methods and very effective means of restoring mandibular function. The functional and morphologic results were excellent and showed little complications.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.351-361
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• 2012

The leading surgical method for correcting the misalignment of the varus and valgus in the knee joint is the high tibial osteotomy (HTO). In the opening wedge HTO (OWHTO), there is no concern about damaging the peroneal nerve on the lateral tibia of the proximal fibula. OWHTO has been the preferred choice, as the opening of the correction angle can be modulated during the operation. The correction of the varus and valgus on the coronal plane are performed adroitly. Nevertheless, there have been numerous reports of unintended changes in the medial tibial plateau and posterior slope angle (PSA). The authors have developed an HTO method using computer-assisted surgery with the aim of addressing the abovementioned problems from an engineer's perspective. CT images of the high tibia were reconstructed three-dimensionally, and a virtual osteotomy was performed on a computer. In addition, this study recommends a surgical method that does not cause changes in the PSA after OWHTO. The results of the study are expected to suggest a clear relationship between the anteromedial cortex oblique angle of each patient and the PSA, and an optimal PSA selection method for individuals.