• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.267-275
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• 2012

In this study, normal wind load and blast wind load are modeled mathematical. And the periodical torque and bending moments transmitted to the main shaft of wind turbine are investigated. A normal wind model assumed, of which the wind velocity is increased according to the height from ground. The average values and the harmonic terms of the transmitted moments are studied on the wind direction of range $-45^{\circ}{\sim}45^{\circ}$ and the bending moment characteristics are examined, which is regarded as the main source of the misalignment of gear train. In normal wind load case, excitation frequency is 3X (X : Rotor speed). When the wind direction is $+22.5^{\circ}$, the horizontal axis of bending moment occur the 50% of main torque. This result leads to edge contact of gear teeth by shaft elastic deformation. In blast wind load case, excitation frequency are 3X,6X,9X. Additional, in the (+) direction of wind load, relative harmonic percentage is increase.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.873-880
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• 2011

As environmental pollution, global warming, and exhaustion of fossil fuel become global issue recently, there has been strong research motivation to develop green energy technology. Along the same line of motivation, some research efforts have been put into the development of environment-friendly bicycle equipped with various smart energy technologies to increase the usability of the bicycle as short-distance transportation. Among the technologies related with new generation bicycle, PAS (power assist system) is one of the most important systems that are essential in efficiently integrating human power and the electrical power supplied by electric motor driven by battery. In this paper, a novel torque sensor technology which is core component for PAS is proposed. Unlike existing technologies, strain gauges are attached to rear shaft directly under the hub bearings, which eliminates the requirement of slip-ring, Furthermore, the sensor is able to not only measure the torque transmitted to driving axle by human but also estimate the position of the gear to which the chain is currently engaged.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.57-61
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• 2005

This paper presents a new colonoscopy training simulator that includes a specialized haptic device and graphics algorithms to transfer haptic sensation through a long and flexible tube, and manage large number of polygons. The developed haptic device makes the colonoscope tube move along the two guiding rods in the translational direction. The torque of the roll motion is transferred by a timing belt and pulleys. A special guide is developed, which allows the force and torque from the motors to be transmitted to the user without loss. The haptic device is evaluated by physicians. One of the important skills of the colonoscopy, jiggling is incorporated for the first time by the developed sensor mechanism using photo-sensors. A colonoscope handle that shares the look, feel, and functions with the actual colonoscope, is developed with the necessary electronics inside. The number of polygons is reduced by an edge-collapse algorithm for real-time simulation. The algorithms to import CT data, to segment the colon image, to extract centerline of the colon, and to construct the colon surface, are integrated into a Colon Modeling Kit system that performs all these processes in real-time.

• The korean journal of orthodontics
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• v.21 no.1 s.33
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• pp.31-51
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• 1991

This study was designed to survey the stress distributions and deflections which were derived from MEAW by the computer-aided three dimensional finite element analysis of teeth and surrounding bone composed of 2839 solid elements and 4621 nodes. MEAW model was also made using the 90 beam elements and the results were expressed by quantitative and visible ways. The findings of this study were as follows. 1 In case of vertical load on the MEAW there were extrusions of anterior teeth and upright effects of the posterior teeth. 2. Without applying the vertical elastics on the MEAW there were intrusions of anterior teeth, but relatively mild force was transmitted to the posterior teeth area. Torque forces were observed on the incisors and molars, and canine was intruded without torque. 3. The magnitudes of forces were different by the amounts of tip back bends of MEAW. 4. The displacements were in inverse proportion to the cross section areas of the wires according to the experiment using the 5 different size arch wires. 5. The difference of deflections between the MEAW and plain arch wire was not so big as the theoretical one but the deflections of MEAW were much more than the plain arch wire in every X, Y, Z direction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1720-1727
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• 2003

The object of this work is to develop the measurement method of the transmission error of the helical gears. For this purpose, experimental set up is designed by 3D CAD software. It consists of the motor, inverter, powdered brake equipment, torque sensor and helical gearbox. In this study, tangential linear accelerometers were used as the methods for the transmission error measurement. the acceleration signals are transmitted to the signal conditioners through the slip rings and the transmission errors are obtained by a specially designed circuit board. The transmission errors are analyzed in the frequency domain. As a result, The periodicity of the transmission error is confirmed in the mesh frequency and its harmonics. The magnitude of harmonic components is very dependent on the natural frequencies of the gear system. It usually increases with the rotational speed. However, it does not always increase with torque.

• Journal of Biosystems Engineering
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• v.26 no.1
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• pp.1-10
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• 2001

Interactions between cage wheel and soil under the wet paddy field condition were analyzed. The cage wheel as a traction aid to driving tires of tractor was attached to the outside of the tires. The driving torque transmitted only to the cage wheel was measured and its effect on the total driving torque by both the tires and cage wheel was analyzed. Mathematical models were developed to predict the soil thrusts y a single lug and by the cage wheel with many lugs, respectively. Experimental results showed that as the diameter of cage wheel increased, positive effects of the cage wheel on the traction also increased. About 33-40% of the total traction force was obtained by the cage wheel with a diameter 1,182mm and 49-55% with a diameter 1,222mm. The peak thrust of the single lug of cage wheel increased by 31% and 59%, respectively when the diameter of the cage wheel increased from 1,182mm to 1,222mm and 1,262mm. The thrust by the cage wheel was estimated by using the developed mathematical models and the results were proved that the models are reliable for the estimation of the traction by the cage wheels.

• Journal of Magnetics
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• v.20 no.2
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• pp.186-192
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• 2015

This paper describes the electromagnetic and mechanical characteristics of coaxial magnetic gear (CMG) with a low gear ratio. The analysis models are restricted to a CMG with a gear ratio of less than 2. The electromagnetic characteristics including transmitted torque and iron losses are presented according to the variation of the gear ratio. The pole pairs of high speed rotor are chosen as 6, 8 and 10 by considering the torque capability. As the gear ratio approaches 1, both iron losses on the ferromagnetic materials and eddy current losses on the rotor permanent magnets are increased. The radial and tangential forces on the modulating pieces are calculated using the Maxwell stress tensor. When the maximum force is exerted on the modulating pieces, the mechanical characteristics including stress and deformation are derived by structural analysis. In CMG models with a low gear ratio, the maximum radial force acting on modulating pieces is larger than that in CMG models with a high gear ratio, and the normal stress and normal deformation are increased in a CMG with a low gear ratio. Therefore, modulating pieces should be designed to withstand larger radial forces in CMG with a low gear ratio compared to CMG with a high gear ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.1
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• pp.112-121
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• 2015

In this paper, powertrain of output split type plug-in hybrid electric vehicle is analyzed for the operation range of speed, torque, and power. First, it is assumed that the efficiency of motor is 100%. And, the speed and torque equations are derived based on the lever analogy. With the above equations, the simulations are performed for the powertrain of output split type plug-in hybrid electric vehicle. From the simulation results, it is found that the output torques of EV1 and series modes are larger than the EV2 and power split modes' ones. It means the EV1 and series modes can be used for the rapid acceleration. But the EV1 and series modes can be used only the velocity of under the 120 km/h. It is because the motor reaches its maximum speed when the velocity is over the 120 km/h for the EV1 and series modes. When the engine is turned on, the engine power is transmitted through the two motors. But, the power split mode shows the power split of engine at the output shaft, and it has the point of zero motor power. Thus, the transmission efficiency of the power split mode can be higher than the series mode's one, it the motor efficiency is considered.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.99-105
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• 1994

In this study, the transverse and the torsional vibration analyses of a precision dynamic drive system with the magnetic coupling are accomplished. The force of the magnetic coupling is regarded as an equivalent transverse stiffness, which has a nonlinearity as a function of the gap and the eccentricity between a driver and a follower. Such an equivalent stiffness is calculated by and determined by the physical law and the calculated equivalent stiffness is modelled as the truss element. The form of the torque function transmitted through the magnetic coupling is a sinusoidal and such an equivalent angular stiffness, which represents the torque between a driver and a follower, is modelled as a nonlinear spring. The main spindle connected to a follower is assumed to a rigid body. And then finally we have the nonlinear partial differential equation with respect to the angular displacements. Through the procedure mentioned above, we accomplish the results of the torsional vibration analysis in a spindle system with the magnetic coupling.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1800-1803
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• 1997

This paper presents new feedback actuators to achieve an accurate position control of a flexible gnatry robot arm. the translational motion in the plane is generated by two d.c.motors and controlled by emplying elecor-rheological(ER) clutch acutators. The generated motion can be continuously controlled by controlling the intensity of lectric field imposed to the ER fluid domain which tunes the transmitted torque of the ER clutch. n the other hand, during control action of the translational motion a flexible arm attached to the moving mass produces undesirable oscillatins due to its inherent flexibility. The oscillations are actively suppressed by applying feedback voltages to piezoceramic acutators bonded on the surface of the flexible arm. The control electric fields to be applied to the ER clutch and the control voltage for the piezoceramic actuator are determined via the loop shaping esign procedures(LSDP) in the H.inf. control technique. Comsequently, an accuate positiion control at the end-point of the flexible am is achieved during planar motion.