• The Journal of the Korean dental association
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• v.58 no.6
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• pp.364-376
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• 2020

Internal derangement of the temporomandibular joint (TMJ) is condition in which articular disc has become displaced from its normal functional relationship with the mandibular condyle and the articular portion of the temporal bone. Common types of internal derangement include disc displacement with reduction (with or without intermittent locking), and disc displacement without reduction (with or without limited opening) classified according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Treatment varies depending on diagnosis. Therefore, differential diagnosis should be made for appropriate treatment.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.235-250
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• 1990

Thirty-nine patients (forty-four joints) who had been diagnosed as having meniscus perforation of the temporomandibular joint by inferior joint space arthrography and had been treated by surgical procedures were evaluated retrospectively. Information of clinical findings, arthrotomographic findings and surgical findings was collected on a standardized form and evaluated. The results were as follows: 1. On the 34 patients of 38 joints which were surgically confirmed perforation of meniscus or its attachments of the temporomandibular joint, there were 29 females and 5 males (5.8:1). The average age was 36 years (range 17 to 70). 2. The common clinical findings of group that had meniscus displacement without reduction and with perforation were pain on the affected joint and limitation of mouth opening. In the group showing meniscus displacement with reduction and with perforation the common clinical findings were pain and clicking on the affected joint. 3. 32 joints (84.2%) were arthrotomographically anterior meniscus displacement without reduction and with perforation, 6 joints (15.8%) showed anterior meniscus displacement with reduction and with perforation. 4. Joints categorized arthrotomographically as having meniscus displacement without reduction and with perforation were less likely to have full translation of the condyle in comparison with the normal or meniscus displacement with reduction and with perforation groups. (p<0.05) 5.The arthrographic findings of 44 joints having meniscus perforation were compared with surgical findings, there were 6 false positive findings of meniscus perforation, the reliability of arthrographic findings of meniscus perforation was a 86.4% correlation with surgical findings. 6. On the site of perforations of 38 joints which were surgically confirmed perforation of meniscus or its attachments, twenty-three of perforations (60.5%) were in location at the junction of the meniscus and posterior attachment, forteen (36.9%) were located at the posterior attachment and one (2.6%) was at the meniscus itself.

• Journal of Oral Medicine and Pain
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• v.23 no.3
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• pp.281-288
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• 1998

The authors treated a 30-years old female patient who visited the Department of Oral Medicine, PNUH due to the chief complaint of limitation of mouth opening. The magnetic resonance imaging following clinical examination was used for establishing an accurate and reliable diagnosis and the patient was diagnosed as having anterior disc displacement without reduction in the right joint and anterior disc displacement with reduction in the left joint. For managing acute anterior disc displacement without reduction, mandible manipulation was applied first focusing on pain control and then stabilization appliance was used for maintenance of joint stabilization. With time, the sign and symptom was remarkably reduced and an active exercise program was recommended to maintain of normal muscle length, increase joint range of motion and develop normal coordination arthrokinematics. As a result of treatment, the patient did not complain discomfort of normal daily activities and it was difficult to consider that the displace disc was not reduced completely, but the improvement in range of motion and joint mobility were remarkably found. Therefore, an exercise program should be considered to maintain joint mobility and be effective as a self-care.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.1
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• pp.46-52
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• 2012

Since the engine and reduction gear in a naval vessel are usually supported by the mounting system separately, the misalignment between the input shaft of the reduction gear and the output shaft of the engine should occur caused by ship motion. In this study, this misalignment is estimated from the linear static analysis assuming that the phase of movements of the engine and reduction gear at low frequency range is same and the dynamic effect is not affect to them. Through comparing the relative displacement of the engine and reduction gear calculated from linear static analysis to that from dynamic analysis as well as experiment, the assumption in this study could be verified.

• Structural Monitoring and Maintenance
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• v.5 no.1
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• pp.111-127
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• 2018

Horizontal displacement of high-rise building is an essential index for assessing the structural performance and safety. In this paper, a novel inclinometer-based method is proposed to address this issue and an algorithm based on three spline interpolation principle is presented to estimate the horizontal displacement of high-rise buildings. In this method, the whole structure is divided into different elements by different measured points. The story drift angle curve of each element is modeled as a three spline curve. The horizontal displacement can be estimated after integration of the story drift angle curve. A numerical example is designed to verify the proposed method and the result shows this method can effectively estimate the horizontal displacement with high accuracy. After that, this method is applied to a practical slender structure - Shanghai Tower. Nature frequencies identification and deformation monitoring are conducted from the signal of inclinometers. It is concluded that inclinometer-based technology can not only be used for spectrum analysis and modal identification, but also for monitoring deformation of the whole structure. This inclinometer-based technology provides a novel method for future structural health monitoring.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.1065-1073
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• 2002

A new damage identification technique using static displacement data is developed to assess the structural integrity of bridge structures. In the conventional damage assessment techniques using dynamic response, it is usually difficult to obtain a significant natural frequencies variation from the measured data because the natural frequencies variation is intrinsically not sensitive to the damage of a bridge. In this proposed identification method, the stiffness reduction of the bridges can be estimated using the static displacement data measured periodically and a specific loading test is not required. The static displacement data due to the dead load of the bridge structure can be measured by devices such as a laser displacement sensor. In this study, structural damage is represented by the reduction in the elastic modulus of the element. The damage factor of the element is introduced to estimate the stiffness reduction of the bridge under consideration. Finally, the proposed algorithm is verified using various numerical simulation and compared with other damage identification method. Also, the effect of noise and number of damaged elements on the identification are investigated. The results show that the proposed algorithm is efficient for damage identification of the bridges.

• Archives of Plastic Surgery
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• v.32 no.1
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• pp.49-54
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• 2005

Evaluations and treatments of nasal bone fracture have been mainly focused on aesthetic aspect, but nose has an important role as an airway. The purpose of this study was evaluation of nasal bone fractures in the view of nasal obstruction and its improvement after reduction. Acoustic rhinometry was applied to the 77 nasal bone fractured patients who received closed reduction from August 2002 to July 2003 and received closed reduction. This was tested twice, before and 6 days after reduction, for all 77 patients and additional acoustic rhinometry was also possible in 26 patients after 6 months. The analysis of acoustic rhinometry were based on data of minimal cross-sectional area(MCA) according to fracture sites(one side, both side and tip) and septal displacement. Mean MCA for all cases before reduction was $0.43{\pm}0.21cm^2$, which was 19% decrease compared to normal adult data($0.53{\pm}0.12cm^2$). Depending on fracture sites the MCA were $0.45{\pm}0.16cm^2$ for one side fracture, $0.35{\pm}0.18cm^2$ for both side fracture, and $0.42{\pm}0.25cm^2$ for tip fracture. The patients with septal displacement showed more severe obstruction than ones without septal displacement, $0.26{\pm}0.26cm^2$ and $0.46{\pm}0.10cm^2$, respectively. The MCA was improved up to $0.50{\pm}0.22cm^2$ after reduction and showed slight decrease after 6 month($0.48{\pm}0.23cm^2$). Based on the results of this study, nasal bone fracture really caused airway obstruction(19% decrease). Both side fracture showed more profound decrease than one side fracture and septal displacement was an important parameter which causes nasal obstruction. Closed reduction improved MCA by 14% right after reduction, and 11% after 6 month follow up.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.4
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• pp.373-382
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• 2000

Temporomandibular disorders arised from joint itself was caused by inflammation or mechanical irritation of the retrodiskal tissues. Histologic changes of the retrodiskal tissues of temporomandibular joint(TMJ) internal derangement, such as inflammatory cell infiltration, hyalinization, myxoid change, fatty change, arterial obliteration, and so on, were reported, but relationships between magnetic resonance imaging(MRI) findings and histologic findings of the retrodiskal tissue were few reported. The purpose of this study was to find histologic changes of the retrodiskal tissues for status of joint and joint effusion in MRI of the temporomandibular joint which had surgical treatment. Materials were surgically treated 52 temporomandibular joints with internal derangement or osteoarthritis in TMJ clinic, Yongdong Severance Hospital. All joints were confirmed by magnetic resonance T1- and T2-weighted imagings bofere surgery. Status of joint was categorized by normal position, disc displacement with reduction, disc displacement without reduction, disc displacement without reduction associated with osteoarthrosis using preoperative MR T1-weighted images. Magnetic resonance evidence of joint effusion was observed in T2-weighted images and classified by its amount; degree 0(not observed), degree 1(small amount), degree 2(moderate amount), degree 3(large amount). Histologic features were observed whether the retrodiskal tissue has inflammatory cell infiltration, myxoid change, hyalinization, chondroid metaplasia and arterial obliteration. The distribution of elastic fibers were also observed. The results were as follows; 1. Inflammatory cell infiltration was not observed in any retrodiskal tissues. 2. MRI findings such as status of joint and evidence of joint effusion did not have significant relationship with myxoid change, hyalinization, chondroid metaplasia, arterial obliteration of the retrodiskal tissues. 3. Hyalinization and chondroid metaplasia were found in 8 joints(15.4%) and 5 joints(9.6%). All of them were found in disc displacement without reduction and disc displacement without reduction associated with osteoarthrosis. 4. Arterial obliteration was observed more frequently in disc displacement without reduction(55.6%) than disc displacement without reduction associated with osteoarthrosis(28.6%). Further studies with proper controls and more materials will be necessary.

• Imaging Science in Dentistry
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• v.36 no.2
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• pp.73-79
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• 2006

Purpose : To describe the MRI findings of the antero-superior attachment of the disc in patients with internal derangement. Materials and Methods : One hundred fifty-six MR images from 40 normal subjects and 55 abnormal subjects were classified into three study groups of normal, anterior disc displacement with reduction and anterior disc displacement without reduction. On both closed- and open-mouth proton density sagittal images, the depiction of the antero-superior attachment of the disc and its demarcation from the disc were evaluated in three cuts of lateral, central and medial one thirds of the condyle. Results : The depiction of antero-superior attachment was more frequent by the order of normal, anterior disc displacement with reduction and anterior disc displacement without reduction groups, and the significant differences were found on lateral cut of the closed images and lateral and central cuts of the open images. In study for the demarcation between the antero-superior attachment and the disc the lateral cut of the closed images and all three cuts of the open images showed significant differences. Conclusion : Open images are useful to show the difference in depiction of the antero-superior attachment of the disc among the TMJ groups.

• Wind and Structures
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• v.27 no.4
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• pp.223-234
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• 2018

In this study, a simplified three-dimensional calculation model is developed for the dynamic analysis of soil-pile group-supertall building systems excited by wind loads using the substructure method. Wind loads acting on a 300-m building in different wind directions and terrain conditions are obtained from synchronous pressure measurements conducted in a wind tunnel. The effects of soil-structure interaction (SSI) on the first natural frequency, wind-induced static displacement, root mean square (RMS) of displacement, and RMS of acceleration at the top of supertall buildings are analyzed. The findings demonstrate that with decreasing soil shear wave velocity, the first natural frequency decreases and the static displacement, RMS of displacement and RMS of acceleration increase. In addition, as soil material damping decreases, the RMS of displacement and the RMS of acceleration increase.