• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.19 no.1
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• pp.55-64
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• 1989

The purpose of this study was to clarify that scintigram was a more effective method than radiogram in the early detection of periapical lesion. Periapical lesions were produced artificially by the opening of the pulp chambers of the lower right 3rd and 4th premolars in 6 dogs. The serial bone scintigrams using 99m-Tc-MDP and periapical radiograms were taken weekly. The uptake counts of the 99-Tc-MDP in the experimental side were compared with those in the control side. The periapical radiograms were interpreted with the joint evaluation by three dental radiologists. The following results were obtained; 1. The radioactivity in the experimental side was increased at the Ist week except one animal in which the radioactivity was increased at the 2nd week. 2. It was observed that increasing amount of radioactivity per week was prominent from the 1st day of experiment to the Ist week, and the 3rd week to the 4th week. 3. The radiographic evidence of the periapical lesions was observed at the 3rd week and became more apparent at the 4th week. 4. Histologically, proliferation of blood vessels and infiltration of chronic inflammatory cells were observed at the 1st week and osteoblasts were found after the 3rd week.

• Journal of The Korean Dental Society of Anesthesiology
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• v.10 no.1
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• pp.13-19
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• 2010

Bruxism is nonfunctional jaw movement that includes clenching, grinding and gnashing of teeth. It usually occurs during sleep, but with functional abnormality of brain, it can be seen during consciousness. Oromandibular dystonia (OMD) can involve the masticatory, lower facial, and tongue muscles and may result in trismus, bruxism, involuntary jaw opening or closure, and involuntary tongue movement. Its prevalence in the general population is 21%, but its incidence after brain injury is unknown, Untreated, bruxism and OMD cause masseter hypertrophy, headache, temporomandibular joint destruction and total dental wear. We report a case of successful treatment of bruxism and OMD after brain injury treated with botulinum toxin A and occlusal appliance. The patient was a 59-year-old man with operation history of frontal craniotomy and removal of malformed vessel secondary to cerebral arteriovenous malfomation. We injected with a total 60 units of botulinum toxin A each masseteric muscle and took impression for occlusal appliance fabrication under general anesthesia. On follow up 2 weeks and 2 months, the patient remained almost free of bruxism. We propose that botulinum toxin A and occlusal appliances be considered as a treatment for bruxism and OMD after brain injury.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.1
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• pp.62-66
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• 2011

Introduction: Endoscope-assisted open reduction and internal fixation (EAORIF) reduces the amount of facial scaring, but limitations, such as the possibility to convert to the open technique and the large learning curve, remain. Materials and Methods: The medical records of 19 patients diagnosed as lateral overridden subcondyle fractures and treated with endoscope-assisted open reduction and internal fixation at Yonsei University Health System from December 2006 to August 2010 were reviewed. Results: 11 patients underwent temporary discomfort or pain such as limitation of mouth opening, temporomandibular joint discomfort, lip paresthesia or facial weakness, but the symptoms disappeared within 3 months. There was no severe long-term complication except 2 patients with re-fractures of operated subcondyles. Conclusion: Subcondyle fracture with lateral overridden proximal segment is a better indication of endoscope-assisted open reduction and internal fixation than a condylar head/neck fracture, or medial overridden subcondyle fracture: allowing an anatomic reduction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.258-264
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• 2016

This paper presents the experimental result and theoretical analysis result to investigate the correlation between the operating force and locking torque for vehicle hood frame. Also, we derived the experimental equations that using the results of experiment and theory. The hood frame is switching-devices used for opening and closing the vehicle hood. It needs the correlation data between locking torques of each joint and operating force of hood frame because the parameters affects the emotional quality of the vehicle. The correlation data for torque and force of hood frame obtained through experiment and theory analysis. Finally, two experimental equations of correlation are derived. Thus, the developed equations show that has high usefulness for the basic design of hood frame of vehicle.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.5
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• pp.335-340
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• 2020

Objectives: This study sought to evaluate the efficacy of injecting botulinum toxin into the masseter and temporal muscles in patients with temporomandibular myofascial pain and sleep bruxism. Materials and Methods: The study was conducted based on a clinical record review of 44 patients (36 females and eight males; mean age, 35.70±12.66 years). Patients who underwent the injection of botulinum toxin into the masseter and temporal muscles for the management of temporomandibular myofascial pain and sleep bruxism were included in the study. Patients were diagnosed based on the Diagnostic Criteria for Temporomandibular Disorders. Sleep bruxism was diagnosed according to the criteria defined by the American Academy of Sleep Medicine. The values of the visual analogue scale (VAS) and range of jaw motion, including unassisted maximum mouth opening (MMO), protrusion, and right and left laterotrusion, were observed preoperatively and postoperatively at one-, three-, and six-month follow-up visits. Results: MMO, movements of the right and the left laterotrusion, and protrusion increased significantly (P<0.05), while VAS ratings decreased significantly at the three follow-up points relative to baseline values (P<0.05). Conclusion: Botulinum toxin is an effective treatment for patients with temporomandibular myofascial pain and sleep bruxism.

• 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.