• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.805-810
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• 1990

Optimal control systems for a radial magnetic bearing are proposed and tested. An electromagnet system model is developed to predict bearing forces as functions of changing coil currents and rotor position. Models of the multi-mass rotor supported by the magnetic bearings are developed and confirmed, and theoretical relationships are expressed in the form of state equation. As a result of computer simulation, the state feedback with optimal procedure is considered to be more effective for magnetic bearing systems than the classical method.

• Journal of Veterinary Clinics
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• v.34 no.4
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• pp.287-290
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• 2017

A 6-month-old, 4.1 kg female Dachshund dog presented with intermittent non-weight bearing lameness of the right thoracic limb. Radiographs revealed caudolateral luxation of the right radial head and a shortened right ulna compared to the contralateral limb. Bone lengthening by distraction of the ulna using the Ilizarov technique was performed following ulnar osteotomy. The rate of distraction was 1.5 mm per day, adjusted a total of 3 times daily for a total distraction distance of 10 mm. The Ilizarov fixator was removed four weeks after surgery. The patient showed knuckling due to radial nerve injury that occurred during limb-lengthening. Corrective osteotomy was performed using a plate and pin for the luxation and deformity of the right radial head. The luxation of the radial head was successfully reduced following surgery. However, the knuckling persisted after surgery. Rehabilitation for radial nerve injury was performed using heat therapy, massage, a passive range of motion exercises, water treadmill exercises, neuromuscular electrical stimulation, leash-walking, and acupuncture. 15 months after surgery, the patient showed satisfactory weight-bearing ambulation without recurrence of lameness. The use of the Ilizarov technique is a good surgical option for the treatment of a patient with congenital elbow luxation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.33-34
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.143-144
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.829-830
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.143-144
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• 2011

• Tribology and Lubricants
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• v.8 no.2
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• pp.64-72
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• 1992

The recent trends of rotating machinery demand high speed and high temperature operation, and the bearing with new material is required to be developed. Ceramic, especially silicon nitride, have been receiving attention as alternative material to conventional bearing steel. Ceramic ball bearing offers major performance advantages over steel bearing, for instance, high speed, maginal lubrication, high temperature, improved corrosion resistance and nonmagnetic capabilities etc.. In this paper, the mechanical characteristics of ceramic ball bearing (hybrid ceramic bearing and all ceramic bearing) were investigated, and the characteristics of ceramic bearing were compared with that of steel bearing. Deep groove ball bearing 6208 was taken the object of analysis. The main results of analysis were followings: the radial stiffness of hybrid and all ceramic bearing were 112% and 130% that of steel bearing, and the axial stiffness of all ceramic bearing was 110% that of steel bearing. According as rotating speed was up, the ball load, the contact angle, the contact stress and the spin-to-roll ratio between ball and raceway of ceramic bearing were far smaller than these of steel bearing. And there was not a significant difference between the minimum film thickness of ceramic bearing and steel bearing. It is expected that this research is contributed to enhanced fundamental technology for the practical applications of ceramic ball bearing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.63-70
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• 2008

In this paper, we propose a bearing redundant coordinates and decoupled PD controller for 5-axes active magnetic bearing system, which consists of two bearing parts such as three-pole hybrid active magnetic bearing for stabilize the radial direction and ring-type permanent magnetic bearing stabilizing in axial and tilting motion. Based on derived system equation with decoupled control scheme, we conduct the modal analysis and measure of modal controllability and observability.

• Tribology and Lubricants
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• v.27 no.1
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• pp.25-33
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• 2011

Rolling contact ball bearings are utilized almost exclusively for liquid propellant rocket engine turbopump. Turbopump ball bearings are required to endure high speed and high load for a poor lubricated condition in cryogenic environment. To evaluate bearing heat generation performance, friction torque is investigated as a function of rotation speed, bearing load and cooling flow rate through an experimental study using water coolants. Radial and axial loads are simultaneously applied to the test bearing by gas pressurized cylinder rod. Endurance performance of bearing has been also verified under the bearing required load for operating condition during total accumulated test time 2,100 sec.

• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.42-51
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• 1996

Taper roller bearing is used on rotating shaft where radial and thrust loads are attended. To avoid the sudden failure and maintain the good condition of rotating machinery it is necessary to monitor the condition of bearing and diagnose the defect of bearing. In this study the diagnosis program of taper roller bearing which is used on the lower bearing of V.A.W.T. (Vertical Axis Wind Turbine) is developed. By plenty of test the database is constructed and by Gaussian distribution obtained from database the defect probability of bearing is calculated.