• Clinics in Shoulder and Elbow
• /
• v.5 no.2
• /
• pp.102-109
• /
• 2002

Purpose: To evaluate the results of the treatment of the supracondylar fractures of the humerus according to the fixation methods in adults Materials and Methods: Seven patients, aged 55 to 52 years (average,69 years), were reviewed after a mean follow-up of 37 months (range, 11-65 months). According to AO classification all fractures were classified as type A2 (simple transverse supracondylar fracture). Six patients underwent closed reduction and one patient, open reduction after failure of closed reduction. Percutaneous fixation with cannulated screws was performed to the 4 patients, per- cuta)leous fixation with Kirschner wires in 3 patients. All except one patients have associated medical problems. The results were assessed based on the Mayo Elbow Performance Score. Results: All the patients with cannulated screw fixation had stable bony union with excellent ranges of motion (mean: 5-125 degrees). All the three patients who received percuatnaous smooth K-wire fixation had nonunion with poor results, one of them had changed into cannulated screw. and then had good result. Conclusion: Although simple supracondylar fracture is similar to the pediatric fracture in nature, it should be firmly fixed with the method such as threaded cannualted screw rather than the simple fixation with K-wires.

• Journal of Korean Orthopaedic Sports Medicine
• /
• v.10 no.2
• /
• pp.109-112
• /
• 2011

Anatomical reduction and strong fixation in displaced patella fracture are needed for restoration of knee function and strength and early range of motion exercise. According to the type of fracture and various operational methods, their many complications have been reported. We report 2 cases of transverse patella fracture which were caused by transverse screw fixation in longitudinal patella fracture and fracture of bipartite patella in athletes.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.1
• /
• pp.154-162
• /
• 1996

Ball screws are commonly used in linear motion feeding systems of various machine tools and automated systems. They are known to have relatively little backlash, high precision and efficiency compared to ordinary lead screws. Furthermore, the effectiveness of ball screw has made it the preferred choice of many newly developed high speed precision feeding units. The motivation of this work is to establish the groove edsigh basis of ball screws for the reduction of contact fatigue failure. In most instances, fatigue failure between ball and shaft groove is due to excessive contact pressure. Especially, the excessive load is causative of plastic flow below the contact surface, which can contribute to surface failure. But, in spite of small load, if groove conformity rate is large, contact pressure is increased and internal shear stress reach the yield value of the material. In such a point, the authors deal with design procedure for deciding the permissible conformity rate of a ball screw groove with the computational evaluation of contact pressure and maximum shear stress.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.7 no.3
• /
• pp.1-16
• /
• 2001

In view of the fact that marine casualties have more often occurred recently, there is a need for ship-handling simulator as a useful tool for maritime training, safety assessment and so on. Moreover various kinds of hull forms have appeared for the purpose of improving ship manoeuvrality. Therefore ship-handling simulator is in need of a database for various ships, and it can make diverse maneuvering simulations possible to apply respective mathematical model to ship-handling simulator. In this paper, we adopted twin-screw and twin-rudder ship and discussed mathematical model of maneuvering motions for her. It was discussed from the viewpoint of hull damping forces at low advance speed and interaction between hull, propeller and rudder. Using this model, maneuvering motion of twin-screw and twin-propeller ship was simulated numerically and her principal manoeuvrability was examined.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.1 s.173
• /
• pp.110-117
• /
• 2000

Vibration modes obtained from a modal analysis can be better explained from a screw theoretical standpoint. A vibration mode can be geometrically interpreted as a pure rotation about the vibration center in a plane and as the twisting motion on a screw in a three dimensional space. This paper, presents the method to diagonalize a spatial stiffness matrix by use of a parallel axis congruence transformation. It also describes that the stiffness matrix diagonalized by a congruence transformation, can have the planes of symmetry depending on the location of the center of elasticity. For a plane of symmetry, any vibration mode can be expressed by the axis of vibration. Analytical solutions for the axis of vibration has been derived.

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

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.05a
• /
• pp.21-24
• /
• 1994

A piezoelectric actuator. which is composed of a piezoelectrically driven stator and a rotor, Is made and the characteristics are investigated experimentally is a new ultrasonic actuator which transforms rotary motion to linear one is proposed and proved to work successfully. If an ultrasonic wave is excited to propagate in the stator, particles on the internal surface move elliptically. Since the internal surface is machined as an internal thread and an external thread(rotor) is put into the stator. the external thread is rotated through the friction force and moved in the axial direction. The traveling wave is excited by a piezoelectric element bonded to the stator. This idea is firstly proposed by S. Ueha, et al. in 1987. However, efficiency of their actuator is less than 3%. In this study, in order to improve characteristics of this type actuator, we used various pitches and number of the screw thread, and materials of rotor, and we obtained good charcteristics.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.1
• /
• pp.21-26
• /
• 2000

This paper describes a positioning system for ultra-precision that will be utilized in semiconductor manufacturing field and precision machinery. This system is composed with laser scale unit with 10nm resolution, ball screw with LM guide, brushless DC servo motor, vibration isolator and is equipped in chamber for continuous measuring environment. The dynamic of table, the problem of servo control and the traceability for micro step motion are described. These data will be applied for getting more stable system with 50nm resolution.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.805-809
• /
• 2003

We developed a human-sized BWR(biped walking robot) named KUBIR1 driven by a new actuator based on the ball screw which has high strength and high gear ratio. KUBIR1 was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. To utilize the information on the human walking motion and to analyze the walking mode of robot, a motion capture system was developed. The system is composed of the mechanical and electronic devices to obtain the joint angle data. By using the obtained data, a 3-D graphic interface was developed based on the OpenGL tool. Through the graphic interface, the control input of KUBIR1 is performed.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.507-510
• /
• 2002

We developed a human-sized BWR(biped walking robot) named KUBIRI driven by a new actuator based on the ball screw which has high strength and high gear ratio. KUBIRI was developed to walk autonomously such that it is actuated by small torque motors and is boarded with DC battery and controllers. To utilize informations on the human walking motion and to analyze the walking mode of robot, a motion capture system was developed. The system is composed of the mechanical and electronic devices to obtain the joint angle data. By using the obtained data, a 3-D graphic interfacer was developed based on the open inventor tool. Through the graphic interfacer, the control input of KUBIRI is performed.