• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.213-230
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• 2008

The aim of this study was to analyze the initial movement and the stress distribution of each tooth and periodontal ligament during the lingual lever-arm retraction of 6 maxillary incisors using FEA. Two kinds of finite element models were produced: 2-properties model (simple model) and 24-properties model (multi model) according to the material property assignment. The subject was an adult male of 23 years old. The DICOM images through the CT of the patient were converted into the 3D image model of a skull using the Mimics (version 10.11, Materialise's interactive Medical Image Control System, Materialise, Belgium). After series of calculating, remeshing, exporting, importing process and volume mesh process was performed, FEA models were produced. FEA models are consisted of maxilla, maxillary central incisor, lateral incisor, canine, periodontal ligaments and lingual traction arm. The boundary conditions fixed the movements of posterior, sagittal and upper part of the model to the directions of X, Y, Z axis respectively. The model was set to be symmetrical to X axis. Through the center of resistance of maxilla complex, a retraction force of 200g was applied horizontally to the occlusal plane. Under this conditions, the initial movements and stress distributions were evaluated by 3D FEA. In the result, the amount of posterior movement was larger in the multi model than in the simple model as well as the amount of vertically rotation. The pattern of the posterior movement in the central incisors and lateral incisors was controlled tipping movement, and the amount was larger than in the canine. But the amount of root movement of the canine was larger than others. The incisor rotated downwardly and the canines upwardly around contact points of lateral incisor and canine in the both models. The values of stress are similar in the both simple and multi model.

• The Journal of the Petrological Society of Korea
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• v.8 no.3
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• pp.131-148
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• 1999

Characteristics and complex structures in the northwest Nevada, U.S.A. are de-veloped due to relative tectonic movement of major tectonostratigraphic terranes. Theresearch area is composed of autochthonous rocks of both Early Triassic Koipato Group and Middle Triassic Star Peak Group, which is located in the Humboldt Range, northwest Nevada, U.S.A. The present research is focused on deformation history, related fabric development, and state of regional paleostress during the Jurassic to Late Cretaceous. The Triassic autochthonous rocks in the Humboldt Range, Nevada, U.S.A. display polyphase deformation due to E- to ESE-directed tectonic transport of the Fencemaker allochthon over autochthonous rocks of the Humboldt Range. Structures involving the Mesozoic foreland deformation are development of intense foliation, different styles of folds, minor thrusts, transposed layering, and strong mylonitization. These tectonic structures are mostly developed along the western flank of the Humboldt Range, and are reported as the first deformation of the Mesozoic foreland in the Humboldt Range, Nevada, U.S.A. Regional principal stress(${\sigma}_1$) is interpreted to be E to ESE between the Jurassic and Early Cretaceous on the basis of orientations of strongly developed $D_1$ structures. The deformation during the Middle to Late Cretaceous, is characterized by development of consistent N- to NNE-trending metamorphic quartz veins, and shear zones parallel to pre-existing $D_1$ foliation. Orientations of metamorphic quartz veins as well as other kinematic indicators are N to NNE and are interpreted as those of regional principal stress(${\sigma}_1$) during the Late Cretaceous. The sense of shear applied in the Humbololt Range is dextral and is caused by reactivation of early-formed $D_1$ structures. These results reflect counterclockwise rotation of regional principal paleostress in the Humboldt Range from the Jurassic to Late cretaceous. Finally, development of both shear band cleavage and S/C mylonitic fabrics indicates that the shear zones in the Humboldt Range reflect involvement of enhanced non-coaxial flow during bulk shortening in mylonitic formation.

• Journal of Korean Orthopaedic Sports Medicine
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• v.10 no.2
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• pp.78-85
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• 2011

Purpose: To evaluate the usefulness of computerized tomography (CT) for the diagnosis and the fragment fixation of anteroinferior tibiofibular ligament avulsion fracture in ankle fracture. Materials and Methods: We retrospectively studied 108 patients with an ankle fracture who had been checked with plain radiographs and CT from July 2006 to July 2010. They were divided into two groups; patients with (19 patients) and without (89 patients) an avulsion fracture of anteroinferior tibiofibular ligament. The two groups were evaluated with Lauge-Hansen classification, the energy of trauma, and the radiologic indices for syndesmotic injury, and were compared each other. Average follow up periods of two groups were 25 and 23 months each. Those who were unstable at stress test during surgery were divided into fragment fixation of anteroinferior tibiofibular ligament avulsion fracture group (8 patients) and transfixation one (11 patients) according to treatment method. Clinical and radiological results at last follow up were also compared. Results: Fourteen avulsion fractures of anteroinferior tibiofibular ligament were diagnosed by CT only. Incidences of pronation-external rotation injury, high energy trauma, positive radiologic indices for syndesmotic injury were significantly higher in patients with an avulsion fracture of anteroinferior tibiofibular ligament than those without it. Clinical and radiological results were satisfactory in both groups at last follow up, and were not significantly different between them. Conclusion: In patients who have an ankle fracture by pronation-external rotation injury, high energy trauma, or with positive radiologic indices for syndesmotic injury, CT is useful for diagnosis of an avulsion fracture of anteroinferior tibiofibular ligament. Fragment fixation of anteroinferior tibiofibular ligament avulsion fracture is a useful treatment option for syndesmotic injury.

• Archives of Reconstructive Microsurgery
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• v.15 no.1
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• pp.17-25
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• 2006

Twelve cases in eleven patients with segmental bone defects were treated with contralateral fibula free flap and ipsilateral island fibula flap in an antegrade, retrograde or bidirectional flow fashion. Five cases were managed with free flaps and seven were with ipsilateral fibula island transfer. Among seven cases, antegrade fashion was three, retrograde was three, and bidirectional was one. All patients were related with open tibial fractures and its sequelae except one who had open foot bone fracture. According to Gustilo's classification, ten patients were type IIIb and one was type IIIc. Basically, antegrade-flow flaps based on the peroneal vessels as in the conventional free flap were used for the proximal or middle one-third tibial defects. On the contrary, retrograde-flow flaps based on the communicating branch between the peroneal and posterior tibial vessels were used for the middle or distal one-third of the tibia. Bidirection-flow flap based on intact peroneal vessels were used for the middle portion of the tibia. The patients who have undergone ipsilateral fibula island flap had one of the following problems: a previously failed free flap, below-knee amputation of the opposite leg because of open tibial fracture, refusal to use the contralateral sound leg, or poor general condition to stand a lengthy operation. Six of the patients who have got ipsilateral fibula island flap also had an associated fibula fracture on the same leg, which was ultimately used as one of the osteotomy sites. The follow-up period was from 1 to 10 years. Two cases of free flap were failed: one patient had below-knee amputation and the other patient had ipsilateral fibula transfer. Other cases were successful and excellent hypertophy of the transferred fibula was achieved. Time to bone union ranged from 4 to 11 months. Time to full weight bearing was from 5 to 13 months after surgery. All of the transferred fibulas showed hypertrophy after weight bearing. In one case, stress fracture was developed during ambulation, which was healed conservatively. Nonunion occurred in two cases, which were treated with a long leg cast and cancellous bone graft, respectively. Length discrepancy of the legs was noted. The limb was shorter by an average 0.5 cm in three cases, longer by 1.1 cm in one case. In the case of island fibula transfer, limited arc of rotation was not a problem. Other disabling complications were not seen. We believe that these diverse modalities using a vascularized fibula will make us more comfortable to handle major bone defects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.29-35
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• 2012

The treatments for spinal canal stenosis are radicular cyst removal, spine fusion, and implantation of an artificial intervertebral disc. Artificial intervertebral discs have been most widely used since the mid-2000s. The study of artificial intervertebral discs has been focused on the analysis of the axial rotation, lateral bending, the degrees of freedom of the disc, and flexion-extension of the vertebral body. The issue of fatigue failure years after the surgery has arisen as a new problem. Hence, study of artificial intervertebral discs must be focused on the fatigue failure properties and increased durability of the sliding core. A finite element model based on an in the artificial intervertebral disc (SB Charit$\acute{e}$ III) was produced, and the influence of the radius of curvature and the change in the coefficient of friction of the sliding core on the von-Mises stress and contact pressure was evaluated. Based on the results, new artificial intervertebral disc models (Models-I, -II, and -III) were proposed, and the fatigue failure behavior of the sliding core after a certain period of time was compared with the results for SB Charit$\acute{e}$ III.

• Journal of Korean Foot and Ankle Society
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• v.26 no.2
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• pp.95-102
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• 2022

Purpose: This study was based on the Korean Foot and Ankle Society (KFAS) member survey and aimed to report the current trends in the management of syndesmotic injuries over the last few decades. Materials and Methods: A web-based questionnaire containing 36 questions was sent to all KFAS members in September 2021. The questions were mainly related to the preferred techniques and clinical experiences in the treatment of patients with syndesmotic injuries. Answers with a prevalence ≥50% of respondents were considered a tendency. Results: Seventy-six (13.8%) of the 550 members responded to the survey. The results showed that the most preferred method to diagnose a syndesmotic injury was magnetic resonance imaging (MRI). Intraoperatively, the external rotation stress test and the Cotton test were most frequently used to confirm syndesmotic diastasis. The reduction was usually done by a reduction clamp. One 3.5-mm screw was used most frequently over three cortices at 2~4 cm above the ankle joint. The preferred ankle position during fixation was 0° dorsiflexion. Removal of the syndesmotic screw was routinely done by most surgeons, mainly because of the limitation of movement and risk of screw breakage. Factors that affect suture button selection included non-rigid fixation which enables adequate fixation, early weight-bearing, and an infrequent need to remove the hardware. Inadequate reduction was considered the main factor that affects poor prognosis. Conclusion: This study proposes updated information about the current trends in the management of syndesmotic injuries in Korea. Consensuses in both the diagnostic and therapeutic approach to patients with syndesmotic injury were identified in this survey study. This study may raise the awareness of the various possible approaches toward the injury and should be used to further establish a standard protocol for the management of syndesmotic injuries.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.613-624
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• 1997

A study of anisotropy of magnetic susceptibility (AMS) was conducted on the Ordovician-Eocene strata in the Taebaek area. The study area is a northeastern part of the Okchon belt, sometimes called as Paegunsan Synclinal Area. A total of 600 independently oriented samples were collected from 60 sites covering the whole area. With a few exception of late Cretaceous-Eocene volcanic rocks, all the sampled strata are nonmetamorphosed sedimentary rocks, mainly sandstones. Among the 60 sites, 5 sites showed flow lineation lying on the bedding plane, 11 sites showed load foliation parallel to the bedding plane, and 21 sites showed tectonic foliation unrelated to the bedding plane. The tectonic foliations are defined by $k_1-k_2$ ($k_{max}-k_{int}$) anisotropy plane, and are considered as a result of tectonic forces acted perpendicularly to the foliation plane in the geologic past. Regardless of sample-site locations, tectonic force directions defined by $k_3$ ($k_{min}$) axis perpendicular to the tectonic foliation are consistent among the strata of the same geologic age. In the course of geologic time, however, the tectonic force directions showed a clockwise rotation: approximately E-W in the Ordovician sites, NW-SE in the Permian sites, N-S in the Triassic sites, and lastly NE-SW in the late Cretaceous-Eocene sites. The pre-Permian directions showed better clustering in the in-situ (geographic) coordinates, while the younger directions become better clustered after the bedding-tilt correction. It is interpreted that the major tectonic structures of the Taebaek area were controlled by the above-mentioned tectonic forces: The Paegunsan Syncline and the Hambaeksan Fault must have been generated by the NW-SE force of late Permian-early Triassic time. It was then reactivated in the reverse (dextral) sense by the N-S force of Triassic time. The Osipchon Fault in the eastern part of the study area was either generated or reactivated by the NE-SW force of late Cretaceous-Eocene time. The Permo-Triassic NW-SE force should be an expression of the Songnim Disturbance in the Korean peninsula, which is in turn related with the SCB/NCB collision in China.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.297-303
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• 2011

The existing studies of VDT syndrome have been researched only about for nurse groups without radiological technologists. The target of this study was workers who perform VDT task in general hospital placed in Daejun City such as insurance judgement, patient affairs, medical record management, medical computing service, hospital administration, and radiological sections. This study was conducted at October 15, 2009 to November 2, 2009 using structured questionnaire. Results of group A (age 20-29, less than 5 years experience at clinical site, normal staff, and unmarried group) showed significant skin and psychological conditions among recognition symptoms of VDT syndrome. Group B (age 30-39, 6-10 years experience at clinical site, managing staff, and married group) tends to be similar at orbital, whole body and muscles' frame response among recognition symptoms of VDT syndrome. Results of "Multiple Linear Regression" with dependent variable that is scores of recognition symptoms of VDT syndrome are as follows. The factors which influences for orbital-related problem is gender, health cares and obstacles during daily life. The factors which influences for whole body-related is exercise, stress and recognition for health condition and the factors which influences muscles' frame-related is 6-10 years experience at clinical site, human relationship, health cares and obstacles during daily life. These are proved to be similar by statistic analysis. There is small difference at recognition symptom of VDT syndrome between the radiological technologist and other groups in general hospital. Yet, as the working circumstance of radiological technologist gradually changes to VDT environment, the recognition symptom of VDT syndrome became conscious. This can be prevented by regular job rotation, which will escape the continuous repetition of working pattern.

• Journal of Korean Orthopaedic Sports Medicine
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• v.2 no.1
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• pp.37-43
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• 2003

Purpose: This study is to analyse the injury patterns of knee ligament and the factors influencing ligament injuries of knee, and to evaluate the changes of knee function and activity after ski injury. Materials and Methods: Thirty cases of ligament injuries of knee were studied with a questionaire, stress radiographs, magnetic resolution imaging, and physical examination. Mean age was 28.6 years old and mean follow up was 29.6 months. Clinical evaluation of Lysholm knee scoring scale was used for knee function and Tegner activity score was used for activity change after ski injury. Results: The anterior cruciate ligament (ACL) injury accompanied with medial collateral ligament(MCL) injury was most in 11 cases and isolated MCL injury was the next in 9 cases. The common types of injury mechanism were Phantom foot phenomenon (13 cases, 43$\%$) and valgus external rotation injury (12 cases, 40$\%$), which constitute 83$\%$ of all case. At the last follow up, the mean Lysholm score was 93.4 and mean Tegner activity score was 4.2. The reduced Tegner activity score after injury was 1.9. Among several injury groups, the evaluation of knee function and activity was best in the isolated MCL injury group and worst in the ACL injury accompanied with MCL injury group. The factors to influence ski injury were participation to ski class, release of binding, and skiing long time more than 2 hours. Conclusions: Lysholm score at last follow up revealed good grading, but sports activity after ski injury was reduced when compared with pre-injury state. It seems to need a active, systemic sports rehabilitation program after sports injury.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.303-312
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• 2008

Multi-axial compression tests have been frequently adopted for the evaluation of material properties of rock cores and rock fracture model tests. Special care has to be applied on the boundary condition between the specimen and loading platen to draw the precise test results of the multi-axial compression tests. With the use of dry steel platen, the stress rotation will occur, due to the frictional restraint from the boundary between the specimen and loading platen. The restraint will deviate the expected test results under the conditions of the given external pressures. Various methods have been applied to reduce the side restraint along the specimen/loading platen interface. The steel brush type loading platen is one example of the attempts. In this paper, a new type of loading platen is introduced to overcome the limitation caused by the use of the brush type loading platen, which requires some internal space for the installation of the brushes. The new type of loading platen, roller supported steel piston type loading platen. is constituted of shot steel pistons which have sufficient stiffness to deliver the external pressure and the shaft type roller installed at the rear of the pistons. The pistons are designed to follow the local deformation of the specimens. In this paper, structural details of the loading platen are presented and frictional and biaxial compression tests results are shown to verify the required functions of the loading platen. Furthermore, calibration process is followed by a comparison between the test results and numerical analyses.