• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1210-1215
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• 2016

• Smart Structures and Systems
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• v.2 no.1
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• pp.61-80
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• 2006

The concept of structural vibration control is to absorb vibration energy of the structure by introducing auxiliary devices. Various types of structural vibration control theories and devices have been recently developed and introduced into mechanical systems. One of such devices is damper employing controllable fluids such as ElectroRheological (ER) or MagnetoRheological (MR) fluids. MagnetoRheological (MR) materials are suspensions of fine magnetizable ferromagnetic particles in a non-magnetic medium exhibiting controllable rheological behaviour in the presence of an applied magnetic field. This paper presents the modelling of an MRfluid damper. The damper model is developed based on Newtonian shear flow and Bingham plastic shear flow models. The geometric parameters are varied to get the optimised damper characteristics. The numerical analysis is carried out to estimate the damping coefficient and damping force. The analytical results are compared with the experimental results. The results confirm that MR damper is one of the most promising new semi-active devices for structural vibration control.

• Clinics in Shoulder and Elbow
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• v.21 no.4
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• pp.240-245
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• 2018

Rare cases of a congenital absence of the long head of the biceps tendon (LHBT) have been reported, and its incidence is unknown. In a literature review of the congenital absence of the LHBT, only 1 case was associated with posterior shoulder instability and severe posterior glenoid dysplasia. This paper reports the first case of a patient with a bilateral congenital absence of the LHBT with posterior shoulder instability without glenoid dysplasia or posterior glenoid tilt. The patient experienced a traffic accident while holding the gear stick with his right hand. After the accident, a posteroinferior labral tear with paralabral cysts was detected on the magnetic resonance images. The congenital absence of the LHBT was assumed to have affected the posterior instability that possibly increased the susceptibility to a subsequent traumatic posterior inferior labral tear. This case was identified as a posterior inferior tear caused by a traumatic 'gear stick injury'.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1065-1070
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• 2017

Magnetic gears are magnetically coupled to the input side and the output side of the rotary machine to transmit power without mechanical contact. The magnetic gear consists of an inner rotor, an outer rotor and pole pieces. Torque ripple occurs due to the difference in reluctance between the two rotors and the pole pieces during power transmission. Torque ripple is a cause of the noise and vibration of the rotary machine, so it is necessary to minimize it. In this paper, we propose a shape that cuts the corner of the pole piece and apply a fillet to reduce torque ripple. We used a two-dimensional finite element analysis method to compare and analyze the torque ripple of the magnetic gears according to the change of the fillet parameters and to find the pole piece shape with excellent torque ripple.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.2
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• pp.93-99
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• 1986

A longline is made of many snoods with baited hooks which are connected to mainline at constant intervals. Hauling the mainline, removing the unused baits and the hooked fish, and the arrangement of hooks are dependent on mainly manual labour as compared with mechanized other fishing gear in fishing operation. The mechanization for longline operation is needed in order to eliminate the manual handling and to shorten the labour time. The magnetic hook splitting apparatus which consists of the hook separator and the guide leading to storage magazine rail was devised for the mechanization of hauling operation. The experiments were carried out in order to measure the splitting rate of hooks in accordance with the hauling speed of mainline and magnetic flux density of splitting apparatus from February to November, 1985. The splitting rate was $94\%$ for the Alaska pollack (Theragra chalcogramma) hook and $96\%$ for the halibut (Paralichthys olivaceus) hook at the hauling speed 24 m/min and magnetic flux density 482 gauss. The unsplitting of hooks was caused by entangling snood in the mainline and low magnetic flux density. The rate is greater the faster hauling speed and the lower magnetic flux density, with an average of about $6\%$, The magnetic flux density needed to hook splitting becomes increased with the increasing hauling speed. When the practical hauling speed is from 20 to 35m/min, the magnetic flux density is needed from 400 to 850 gauss.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2307-2316
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• 2017

The aim of this paper is to provide an optimal design of in-wheel motor for an electric scooter (E-scooter) considering economical production. The preliminary development in-wheel motor, which has a direct-driven outer rotor type attached to the E-scooter's rear wheel without any gear, is introduced first. The objective of the optimal design of this in-wheel motor is to improve the output characteristics of the motor and to have a stator form to facilitate automatic winding. Response surface methodology was used for the optimal design and 2-dimensional finite element method was used for electro-magnetic field analysis. Experimental results showed that the designed and fabricated in-wheel motor could satisfy the required specifications in terms of speed, power, efficiency, and cogging torque.

• Journal of the Korean Institute of Navigation
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• v.19 no.3
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• pp.11-19
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• 1995

When an automatic course keeping is introduced, as is quite popular in modern navigation, the closed-loop control system consists of autopilot device, power unit, steering gear, ship dynamics, and magnetic or gyrocompass. We derive mathematical models of each element of the automatic steering system. We provide a method of theoretical analysis on the propulsive energy loss related to automatic steering of ships in the open seas, taking account of the on-off(non-linear) characteristics of power unit. Also we paid attention to non-linear element installed in autopilot device, which is normally called weather adjuster. Next we make numerical calculation of the effects of autopilot control constants on the propulsive energy loss for two kinds of ship, a fishing boat and an ore carrier. Realistic sea and wind disturbances are employed in the calculation.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.584-587
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• 1992

Because linear motor directly drives linear motion, it does not need conversion equipment such as belt and gear. Especially linear pulse motor provide more precise positioning and large force of linear pulse motors. As current manufacture technic of linear pulse motor is much to be desired at home. This motor lay out to make use of computer aided design program, In this paper the experimental motor is 2-phases 4-poles hybrid pulse motor which has teeth per pole Simulation program is divided its function into 4 parts - air gap permeance analysis, permanent magnet & non-linear core operating point determine, winding configuration, leakage flux analysis. It is possible to make motor static and magnetic characteristics for this simulation program. Also, by varying input parameters of the program, experimental motor is to be compared to motor characteristics.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.134-139
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• 2000

Evaporating heat transfer characteristics of R-22 were measured inside smooth horizontal copper tubes with inner diameters of 3.36 mm and 5.35 mm respectively. The experiments were conducted in the closed loop which was driven by a magnetic gear pump. Experiments were performed for the following range of variables ; mass velocity of refrigerants (200 to 400 $kg/m^2$ .s) saturation temperature ($0^{\circ}C, \; 5^{\circC$}) and quality (0 to 1.0) The main results obtained are as follows : Evaporating heat transfer coefficients in the small diameter tubes (ID<7 mm) were observed to be strongly affected by a variety of diameters and to differ from those in the large diameter tubes. The heat transfer coefficients of the small diameter tubes are higher than those of the large diameter tubes. Comparing the heat transfer coefficients between experimental results and some well-known previous predictions (Shah's correlation Gungor-Winterton's and Kandlikar's correlation) it was very difficult to apply those to small diameter tubes.

• Journal of the Korean Institute of Navigation
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• v.22 no.1
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• pp.79-89
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• 1998

When an automatic course-keeping is concerned , as is quite popular in modern navigation, the closed-loop steering system consists of autopilot device, power unit(or telemotor unit), steering gear, magnetic or gyro compass and ship dynamics. In order to estimate steering system of ship in open seas, we need to know the characteristics of each component of the system and also to know the characteristics of disturbance to ship dynamics. Calculation methods of irrgular disturbances are based on the linear superposition principle. In this paper, for the purpose of evaluation of automatic steering of ships , the influences of linear control constants of autopilot on propulsive energy loss are investigated bya performance index is introduced from the viewpoint of energy saving. Numberical calculations are carried out for an are carrier and for a fishing boat in multi-directional waves.