• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.32-38
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• 2001

This paper presents an approximate synthesis of 5-SS multi link suspension for 2 D.O.F motions. In the proposed synthesis method, alteration curves of camber, toe, kingpin and caster angles are optimized during the bump rebound and the steering motions. And joint positions can be located within desired boundari es. Especially, steering motions are considered for control of kingpin offset and caster trail. Prescribed motions contain both wheel center positions and imaginary kingpin axes in the multi link type suspension. Constraint equations are formulated with di splacement matrix and velocity matrix using instantaneous screw axis.

• Journal of Korean Neurosurgical Society
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• v.48 no.4
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• pp.367-370
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• 2010

We present a case of posterior atlantoaxial screw-rod fixation in a patient with an aberrant vertebral artery (VA) course combined with bilateral high-riding VA. An aberrant VA which courses below the posterior arch of the atlas (C1) that does not pass through the C1 transverse foramen and without an osseous anomaly is rare. However, it is important to consider an abnormal course of the VA both preoperatively and intraoperatively in order to avoid critical vascular injuries in procedures which require exposure or control of the VA, such as the far-lateral approach and spinal operations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.15-18
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• 2000

We developed a human-sized BWR(biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. The robot overcomes the limit of the driving torque of conventional BWRs. Each leg of the robot is composed of three pitch joints and one roll joint. In all, a 10 degree-of-freedom robot with two balancing joints was developed. The BWR was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. In the performance test, the BWR performed nice motions of sitting-up and sitting-down. Through the test, we could find capability of high performance in biped-walking.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.105.6-105
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• 2002

Contents 1We developed a new type of lower part of the human-sized BWR (biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. Each leg of the robot is composed of three pitch Joints and one roll joint. In all, a 8 degree-of-freedom robot was developed. A new type of actuator for the robot is proposed, which is composed of four bar link mechanism driven by the ball screw. The BWR was designed to walk autonomously by adapting small DC motors for the robot actuators and has an embeded controller system including host computer, batteries and motor drivers. In the performance test, we had basic stable walking data so far, but we f...

• Journal of the Korean Arthroscopy Society
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• v.13 no.1
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• pp.53-57
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• 2009

The pretibial cyst is a very rare complication after anterior cruciate ligament (ACL) reconstruction. It occurs whatever kind of graft choice or kind of graft fixation method at tibial side. It have been known such as graft necrosis at tibial side, extra-articular leakage of joint fluid through tibial tunnel, foreign body reaction due to breakdown of the bioabsorbable screw and incomplete incorporation of graft to bony tunnel as the cause of pretibial cyst. We experienced one case of pretibial cyst which had undergone ACL reconstruction with autogenous hamstring graft fixed with biodegradable interference screw. We report a rare case of pretibial cyst with literature review.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.267-267
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• 2000

We developed a human-sized BWR(biped walking robot) driven by a new actuator based on the ball screw which has high strength and high gear ratio. The robot overcomes the limit of the driving torque of conventional BWRs. Each leg of the robot is composed of three pitch joints and one roll joint. In all, a 10 degree-of-freedom robot with two balancing joints was developed. The BWR was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. In the performance test, the BWR peformed nice motions of sitting-up and sitting-down. Through the test, we could find capability of high performance in biped-walking.

• The Journal of Korea Robotics Society
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• v.8 no.1
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• pp.8-19
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• 2013

One of the important issues for structural and electrical specifications in developing a robot is to determine lengths of links and motor specifications, which need to be appropriate to the purpose of robot. These issues become more critical for a gait rehabilitation robot, since a patient wears the robot. Prior to developing an entire gait rehabilitation robot, designing of a 1DOF assistive knee joint of the robot is considered in this paper. Human gait motions were used to determine an allowable range of knee joint that was rotated with a linear type actuator (ball-screw type) and links. The lengths of each link were determined by using an optimization process, minimizing the stroke of actuator and the total energy (kinetic and potential energy). Kinetic analysis was performed in order to determine maximum rotational speed and maximum torque of the motor for tracking gait trajectory properly. The prototype of 1 DOF assistive knee joint was built and examined with a impedance controller.

• Journal of the Korean Arthroscopy Society
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• v.10 no.2
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• pp.141-147
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• 2006

Purpose: To compare the clinical and radiological results of anterior cruciate ligament(ACL) reconstruction using hamstring autograft and tibialis tendon allograft. Materials and Methods: Twenty four ACL reconstructions using hamstring autograft and 30 using tibialis anterior tendon altograft were followed up at least 1 year. We performed femoral tunnel fixation with Ligament Anchor(LA) screw and tibial tunnel fixation with biodegradable interference screw. Evaluations included Lysholm knee(LK) score, Tegner activity scale, Lachman test, Pivot-Shift test, Quardriceps atrophy, incision site numbness, anterior knee pain and instrumented anterior laxity with $Telos^{(R)}$ device. Results: Preoperativ mean LK score was $60.3(18{\sim}82)$ in autograft group and 61.2(25-80) in allograft group. Mean LK score improved to $91.6(68{\sim}100)\;and\;92.6(77{\sim}100)$ respectively. Activity level, using Tegner activity scale, slightly decreased compared with that of Preinjury state in both groups. Lachman test, pivot-shift test, Quadriceps atrophy, anterior knee pain, incision site numbness, and anterior drawer test using $Telos^{(R)}$ device showed no significant difference between two groups (p>0.05). Conclusion: In performing the ACL reconstruction, there was no statistically significant difference between hamstring autograft group and tibilis anterior allograft group in clinical or in radiological results.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.3
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• pp.206-214
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• 2014

This study is to evaluate how different bearing surface angles of abutment screw affect the mechanical stability of the joint in the conical seal design implant system. Materials and Methods: Internal connection type regular implants, two-piece cemented type abutments and tungsten carbide/carbon-coated titanium alloy abutment screws were selected. Titanium alloy screws with conical ($45^{\circ}$) and flat ($90^{\circ}$) head designs which fit on to abutment were fabricated. The abutments were tightened to implants with 30 Ncm by digital torque gauge. The loading was applied once to the central axis of abutment. The mean axial displacement was measured using micrometer before and after the tightening and loading (n = 5). The abutment was tightened to implants with 30 Ncm and T-shape stainless steel crown was cemented. Then the change in the amount of reverse-torque was measured after the repeated loading to the central axis, and the place 5 mm away from the central axis. Compressive bending and fatigue strength were measured at the place 5 mm away from the central axis (n = 5). Results: Both groups showed the largest axial displacement when abutment screw tightening and total displacement was greater in the flat head group compared to conical head group (P < 0.05). However, there were no significant differences in reverse torque value, compressive bending and fatigue strength (P > 0.05). Conclusion: Within the limitations of this study, the abutment screw head design had no effect on two groups regarding the joint stability, however the conical head design affected the settlement of abutment resulting in the reduced total displacement.

• Journal of Korean Foot and Ankle Society
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• v.18 no.1
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• pp.29-35
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• 2014

Purpose: The purpose of this study is to compare the radiologic and clinical results of syndesmotic screw fixation and posterior malleolar fixation for syndesmotic injury in Lauge-Hansen classification pronation-external rotation (PER) stage IV ankle fractures with posterior malleolus fracture. Materials and Methods: We designed a retrospective study that included patients with Lauge-Hansen classification PER stage IV ankle fracture with posterior malleolus fracture. Of 723 patients who underwent ankle fracture surgery from March 2005 to November 2012, 29 were included in this study. In this study, syndesmotic injury was treated with syndesmotic screw fixation or posterior malleolus fixation. There were 15 cases of syndesmotic screw fixation and 14 cases of posterior malleolar fixation. We compared the radiologic and clinical results at one year postoperatively. Posterior malleolus fragment size on a pre-operative computed tomographic image, and tibiofibular overlap, medial clear space, articular step-off, Kellgren-Lawrence grade, and Takakura classification on a postoperative one year followup radiograph were used for comparison of the radiologic results. The clinical results were assessed using the American Orthopaedic Foot and Ankle Society score, visual analogue scale score, and patient subjective satisfaction score. Results: Posterior malleolar fragment size was $12.62%{\pm}3.01%$ of the joint space in the syndesmotic screw fixation group and $27.04%{\pm}4.34%$ in the posterior malleolar fixation group. A statistical difference was observed between the two groups. However, other results, including tibiofibular overlap, medial clear space, articular step-off, Kellgren-Lawrence grade, Takakura classification, and clinical scores showed no statistical difference. Conclusion: In the Lauge-Hansen classification PER stage IV ankle fracture with posterior malleolus fracture, if the posterior malleolus fracture can be reduced anatomically and fixated rigidly, syndesmotic screw fixation, which can cause several complications, is usually not required for achievement of a satisfactory syndesmotic stability; this would be a recommendable option for treatment of syndesmotic injury.