• The Journal of the Korean bone and joint tumor society
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• v.9 no.2
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• pp.200-205
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• 2003

Purpose: To report our experiences of clinical features, treatment method and results of giant cell tumor of 5 patients in proximal fibula. Materials and Methods: Five patients managed with an en bloc resection preserving common peroneal nerve and lateral collateral ligament reconstruction with biceps femoris tendon followed up between January 1997 and July 2001. Preoperative plain radiograph and MRI and bone scan were checked. The recurrence of the tumor was judged by plain radiograph and clinical signs. Lateral instability of knee joint was checked during the outpatient follow-up. Results: The mean age of the patients at the time of operation was twenty- three (21-29). There were one male and four female patients. Dull pain was main symptom and palpable mass was seen in two patients. Peroneal nerve palsy and local recurrence were not observed except one case of temporary peroneal nerve palsy. During the outpatient follow up, one among 5 patients showed slight lateral instability and the other 4 patients showed no instabililty. Conclusion: Giant cell tumor in proximal fibula managed with an en bloc resection preserving common peroneal nerve and lateral collateral ligament reconstruction with biceps femoris tendon showed favorable results.

• Journal of Korean Foot and Ankle Society
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• v.8 no.2
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• pp.149-152
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• 2004

Purpose: We assessed the clinical results of modified Brostrom procedure as a revision method after failure of a primary reconstruction. Materials and Methods: This is a retrospective study of seven patients treated with Modified Brostrom procedure after failed lateral ankle ligament reconstruction between 1996 and 2002. Instability symptom developed average 4.7 month after the initial reconstruction surgery at other clinics. All patients had significant functional impairment before surgery and not responded to conservative protocols. Modified Brostrom procedure was applied to all patients. Results: The average follow up was 51 months (18 to 84). Seven of eight patients had clinical stability following revision reconstruction, six patients (75%) returned to their previous functional level. American Orthopaedic Foot and Ankle Society ankle-hindfoot scores averaged 87.5. There is no difference in active or passive range of motion of plantar flexion or dorsiflexion when compared to the contralateral ankle. However, three patients were noted to have lost some degree of inversion when compated to contralateral ankle. Two patients had osteochondral lesion and multiple spurs and had pain around the ankle that prevented their full recovery. One patient complained of persistent pain which was considered complex regional pain syndrome. Conclusion: Though the outcome of the Modified Brostrom procedure as a method of revision surgery was less satisfactory compared to the results of primary ankle reconstruction, it would be an appropriate option when concomitant abnormalities were not accompanying.

• Journal of Korean Neurosurgical Society
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• v.55 no.5
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• pp.255-260
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• 2014

Objective : The purpose of this study was to compare the radiological and neurological outcomes between two atlantoaxial fusion method for atlantoaxial stabilization; C1 lateral mass-C2 pedicle screws (screw-rod constructs, SRC) versus C1-2 transarticular screws (TAS). Methods : Forty-one patients in whom atlantoaxial instability was treated with atlantoaxial fixation by SRC group (27 patients, from March 2005 to May 2011) or TAS group (14 patients, from May 2000 to December 2005) were retrospectively reviewed. Numeric rating scale (NRS) for pain assessment, Oswestry disability index (ODI), and Frankel grade were also checked for neurological outcome. In radiologic outcome assessment, proper screw position and fusion rate were checked. Perioperative parameters such as blood loss during operation, operation time, and radiation exposure time were also reviewed. Results : The improvement of NRS and ODI were not different between both groups significantly. Good to excellent response in Frankel grade is shown similarly in both groups. Proper screw position and fusion rate were also observed similarly between two groups. Total bleeding amount during operation is lesser in SRC group than TAS group, but not significantly (p=0.06). Operation time and X-ray exposure time were shorter in SRC group than in TAS group (all p<0.001). Conclusion : Both TAS and SRC could be selected as safe and effective treatment options for C1-2 instability. But the perioperative result, which is technical demanding and X-ray exposure might be expected better in SRC group compared to TAS group.

• Journal of Korean Foot and Ankle Society
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• v.13 no.1
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• pp.40-45
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• 2009

Purpose: End-stage ankle arthritis is frequently combined with ankle-hindfoot deformity or ankle instability and therefore additional surgical procedures are often required when performing total ankle arthroplasty. We report the short term clinical and radiographic results of the total ankle arthroplasty with/without the combined adjunctive surgical procedures. Materials and Methods: The study is based on the 17 ankles (16 patients) of end-stage ankle arthritis that were treated with $HINTEGRA^{(R)}$ Total ankle prosthesis (Newdeal, Lyons, France) total ankle arthroplasty (TAA) from 2004 to 2007 with at least 12 months follow-up. The combined adjunctive procedures as well as the VAS pain score, AOFAS score, radiographic measurements and patient satisfactions were evaluated. Results: Average follow-up period was 29 months (13${\sim}$55 months), and the age was average 62 years (39${\sim}$75 years) old. Among total of 17 ankles, varus deformity and lateral ankle instability were found in 4 cases and 3 cases respectively. Twenty additional procedures such as Achilles triple hemisection (9), calcaneal displacement osteotomy (4) and lateral ankle ligament reconstruction (3) were performed in adjunct to TAA in 13 ankles. VAS pain score improved from preoperative average 8.4 (7${\sim}$10) to 2.0 (0${\sim}$5) and the AOFAS functional score improved from 41.8 points (13${\sim}$71 points) to 90.6 (77${\sim}$100 points) at final follow-up. Ninety-four percent of the patients were satisfied with the surgery. Conclusion: We confirmed that many adjunctive combined surgical procedures are often necessary in addressing the end-stage ankle arthritis (74%) with total ankle arthroplasty. We also achieved quite good clinical and radiographic short term results, although the long term follow-up study with larger number of cases are needed in the future.

• Journal of Korean Orthopaedic Sports Medicine
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• v.10 no.2
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• pp.69-77
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• 2011

Purpose: This study was retrospectively performed to compare the clinical outcomes of modified Brostrom procedures using the single suture anchor and the double suture anchor for chronic lateral ankle instability. Materials and Methods: Thirty-seven patients were followed up for more than 1 year after the modified Brostrom procedures using suture anchor. Single surgeon treated seventeen cases with single suture anchor and 20 cases with double suture anchor. The clinical evaluation was performed according to the Karlsson scale and Sefton grading system. Radiologic measurement of the talar tilt and anterior talar translation was performed through anterior and varus stress radiographs using Telos device. Results: The Karlsson scale had improved significantly from preoperative average of 45.2 points to 89.4 points in single suture anchor group, and from 46.4 points to 90.5 points in double suture anchor group. According to the Sefton grading system, 15 cases (88.2%) in single suture anchor group and 18 cases (90%) in double suture anchor group achieved satisfactory results. The talar tilt angle and anterior talar translation had improved significantly from preoperative average of $13.6^{\circ}$ and 8.6 mm to $5.4^{\circ}$ and 4.1 mm in single suture anchor group, from $14.1^{\circ}$ and 8.4mm to $3.9^{\circ}$ and 4 mm in double suture anchor group. Double suture anchor technique was significantly superior in postoperative talar tilt. Conclusion: Single and double suture anchor techniques produced similar clinical and functional outcomes except for talar tilt, which was significantly superior in double suture anchor group. Both modified Brostrom procedures using the single and double suture anchor appear to be effective treatment methods for chronic lateral ankle instability. Further evaluation of clinical outcomes and biomechanical studies in athletes are needed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1914-1922
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• 2004

This paper provides a comprehensive study of optimum design of a helicopter tailrotor driveshaft made of the flexible matrix composites (FMCs). Since the driveshaft transmits power while subjected to large bending deformation due to aerodynamic loadings, the FMCs can be ideal for enhancing the drivetrain performance by absorbing the lateral deformation without shaft segmentation. However, the increased lateral flexibility and high internal damping of the FMCs may induce whirling instability at supercritical operating conditions. Thus, the purpose of optimization in this paper is to find a set of tailored FMC parameters that compromise between the lateral flexibility and the whirling stability while satisfying several criteria such as torsional buckling safety and the maximum shaft temperature at steadystate conditions. At first, the drivetrain was modeled based on the finite element method and the classical laminate theory with complex modulus approach. Then, an objective function was defined as a combination of an allowable bending deformation and external damping and a genetic algorithm was applied to search for an optimum set with respect to ply angles and stack sequences. Results show that an optimum laminate consists of two groups of layers: (i) one has ply angles well below 45$^{\circ}$ and the other far above 45$^{\circ}$ and (ii) the number of layers with low ply angles is much bigger than that with high ply angles. It is also found that a thick FMC shaft is desirable for both lateral flexibility and whirling stability. The genetic algorithm was effective in converging to several local optimums, whose laminates exhibit similar patterns as mentioned above.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.6
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• pp.422-428
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• 2019

A tailless or Blended-Wing-Body(BWB) shaped configuration is highlighted for UCAV with low RCS characteristics. The BWB configuration is characterized by its directional static instability and low controllability. To control the directional movement of the BWB configured vehicle, directional thrust vectoring equipment or drag rudder typed control surfaces which utilize the drag differences of the wing can be considered. This paper deals with a BWB shaped configuration using a spoiler and describes the lateral-directional aerodynamic characteristics of the vehicle. In addition, it is shwon that the lateral-directional motion can be controlled effectively by using the classical PI control structure. This control law is verified by flight test and showed adequate for the tailless BWB shaped UAV.

• Journal of Korean Neurosurgical Society
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• v.41 no.2
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• pp.141-144
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• 2007

A vertebral arte [VA] injury presents a difficult problem in atlantoaxial fixation. Recent technical reports described posterior C2 fixation using bilateral, crossing C2 laminar screws. The translaminar screw technique has the advantages of producing little risk of VA injury and the unconstrained screw placement. In addition, biomechanical studies have demonstrated the potential of the translaminar screw technique to provide a firmer construct that is equivalent to methods currently used. We report the successful treatment of C1-2 instability with a left-side high-riding VA. Because of the potential risk of VA injury, we performed a posterior C1-2 fixation with a combination of pedicle screws and a laminar screw in C2. We first placed bilateral C1 lateral mass screws and a right-side C2 pedicle screw. However, placement of the left- side C2 pedicle screw was technically difficult due to a narrow isthmus and pedicle. A laminar screw was inserted instead and authors believe that this posterior C1-C2 fixation with a combination of pedicle screws and a laminar screw in C2 can be a useful alternative technique for the treatment of C1-C2 instability in the presence of a unilateral high-riding VA.

• Journal of Korean Neurosurgical Society
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• v.50 no.6
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• pp.528-531
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• 2011

Although posterior segmental fixation technique is becoming increasingly popular, surgical treatment of craniovertebral junctional disorders is still challenging because of its complex anatomy and surrounding critical neurovascular structures. Basilar invagination is major pathology of craniovertebral junction that has been a subject of clinical interest because of its various clinical presentations and difficulty of treatment. Most authors recommend a posterior occipitocervical fixation following transoral decompression or posterior decompression and occipitocervical fixation. However, both surgical modalities inadvertently sacrifice C0-1 and C1-2 joint motion. We report two cases of basilar invagination reduced by the vertical distraction between C1-2 facet joint. We reduced the C1-2 joint in an anatomical position and fused the joint with iliac bone graft and C1-2 segmental fixation using the polyaxial screws and rods C-1 lateral mass and the C-2 pedicle.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.7
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• pp.796-804
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• 2011

Railway vehicles are capable of indicating several types of instability. This phenomenon, which is called hunting motion, is a self excited lateral oscillation that is caused by the running velocity of the vehicle and wheel frail interactive forces. The interactive forces act to change effectively the damping characteristics of railway vehicle systems. This paper will show the impact of instability on the transfer function behavior using damping characteristics of secondary suspension. The vehicle dynamics are modeled using a 17 degree of freedom considering linear wheel/rail contact. The paper deals with certain condition of the damper characteristics that one is about various damping coefficient and another is equipped damper direction.