• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1507-1516
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• 2001

An analytical method is presented for evaluation of the steady state periodic behavior of nonlinear structural systems. This method is based on the substructure synthesis formulation and a harmonic balance procedure, which is applied to the analysis of nonlinear responses. A complex nonlinear system is divided into substructures, of which equations are approximately transformed to modal coordinates including nonlinear term under the reasonable procedure. Then, the equations are synthesized into the overall system and the nonlinear solution for the system is obtained. Based on the harmonic balance method, the proposed procedure reduces the size of large degrees-of-freedom problem in the solving nonlinear equations. Feasibility and advantages of the proposed method are illustrated using the study of the nonlinear rotating machine system as a large mechanical structure system. Results obtained are reported to be an efficient approach with respect to nonlinear response prediction when compared with other conventional methods.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.411-416
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• 2002

In a high speed spindle system, it is very important to monitor the state of rotating rotor. Particularly in active control spindle system, the position sensor must provide feedback to the control system on the exact position of the rotor. In order to monitor the state of a high speed spindle exactly, high accuracy and wide frequency bandwidth of sensors are important. The focus in this paper is to make a fiber optic sensor for monitoring rotor of magnetic bearing, to design the circuit for detecting optical signal, and to evaluation static and dynamic characteristics of fiber optic sensor.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.29-35
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• 2009

Butterfly valve is a kind of rotational valve which opens and closes the flow of fluid on rotating the disk 90 degrees in the valve body. In this paper, butterfly valve design safety evaluation which is based on the international valve specifications is investigated. Both body and disk of the butterfly valve are considered under the normal and pressurized operating conditions. A finite element analysis is carried out to compute the distribution of the displacement, stress and safety factor by using ANSYS. On the basis of calculated design safety we offer the design modification and compare with them.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.9-14
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• 2007

In this paper, a rotating tool clamping device was developed based on a shape memory alloy(SMA) and its feasibility as a tool holder was experimentally explored. The SMA-based device was able to alter clamping to unclamping through temperature control within 1 second. The means and repeatability(${\sigma}$) of the tool clamping force were 185.5N and 6N respectively and its drifts were less than 3% for an hour. Considering the temperature hysteresis of the SMA-based tool clamping device, it is necessary to heat the SMA ring to around $50^{\circ}C$ after tool change to obtain more clamping force.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.119-125
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• 2008

A new type of swivel unit is suggested in order to complement weak points of the existing. This new type of Swivel unit is developed by adopting a spring type cable which has elasticity and restoring force. To minimize the troubles in the process of manufacturing during operating the new type system, strength analysis and the check of interference between parts are accomplished with CATIA. The check of rotating performance is also carried out to determine the diameter and length of spring type cable by SimDesigner motion analysis. Swivel unit used in the robot spot welding is developed with spring type cable and its usefulness in the industrial field is verified through experiments. This system has been registered for patent.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.23-29
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• 2008

This study analyzes the rolled circular rod strip with radius of loom and length of 350cm by using finite element analysis. The material strength and its durability of the rolled strip can be predicted through this study. As the penetration tolerance by contact decreases, the contact rigidity of strip increases. As the contact rigidity becomes the highest at the elapsed time of 1.2 second, the contact stress becomes the lowest. On the contrary, von-Mises stress becomes highest at this time. The total deformation on strip increases from the upper part of strip at the position near to rotating roll to the lower part of strip at the position near to fixing roll.

• Bulletin of the Society of Naval Architects of Korea
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• v.9 no.2
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• pp.33-42
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• 1972

This paper was studied on the behavior, crack formation and propagation of slip bands on low carbon steel which was heat-treated in three conditions in order to change metallic structure. The specimens were tested by rotating bending fatigue testing machine and also observed the variations of grains by microscope. From the test results it was clear that fatigue endurance limit and life of low carbon steel were more increased in contrast with the case that the grain size of specimen was more decreased. Slip bands developed at oil-quenched specimen and furnace-cooled specimen. Formed cracks in the first one or two grains below the surface were approximately "planar" type, there after they followed "wavy" type. It was also found that cracks at 30% higher stress than fatigue limit were usually developed inter-granular, and cracks at 12% higher stress than fatigue limit were propagated meandering path, partly trans- and partly inter-grandular.

• 전기의세계
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• v.15 no.5
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• pp.32-39
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• 1966

This voltage Regulator, which regulates voltage in different way from the conventional regulator, is constructed by circular-plate core type stators and controllers (are similar to rotor of conventional). The principle of this Voltage Regulator is based on the rotating magnetic field theory including peculiar homopolar and heteropolar concept. Comparing with the conventional induction regulator, this regulator need not to have short windings and can cancel armature reaction. Moreover, it is able to decrease the machine noise and control the phase of it freely. And it's efficiency can become more than 95% which almost the same as that of transformer's. By increasing numbers of cores of the same size, the output power can be increased, the insulation can be decreased and high Voltage can directly be connected because applied voltage is distributed to each core. This Voltage Regulator can be also used as a current regulator, a starter a induction motor and a phase transformer etc.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.6-15
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• 2003

A method is presented for diagnosing the converter bearings by using acoustic emission. The flaking mechanism causing the large-scale bearing for furnace to flaw is investigated and a possibility of defect is verified by Finite Element method. he diagnosis logic is proposed fir detecting the flaw of a non-continuous rotating machine. It is proved that the acoustic emission energy can be used as a representative parameter for an acoustic event. Applying the method to the tilting bearings for steel mill in operation, the effectiveness of this logic is evaluated. It is shown that AE signal is generated only when the bearing is tilting, and the trend analysis can be focused upon this process.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.690-692
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• 2003

The single phase switched reluctance motor has been studied and developed actively in the various applications with several kinds and forms because of the developments of the design technique by using the computer and of the driving technique power electronic technology, which has the merits of a simple and robust structure, and first of all reducing the number of the switching devices in comparison with poly phase switched reluctance motor. And also, the studies are making progess to substitute the switched reluctance motor for single phase induction motor. In the previous studies, the single phase switched reluctance motor for the drive of blower is designed with the design theory of the conventional rotating electric machine and poly phase switched reluctance motor. In this paper, we intend to select the optimal pole arc and pole pitch ratio by the FEM analysis, because the pole arc and pole pitch are very important factor to determine the characteristics of switched reluctance motor.