• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.3-5
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• 2005

The overhang parameter is required to maximize the power density of generator. However, the use of overhang design causes the rise of material cost. Moreover there is somewhat different overhang effect according to the rotor types. This paper presents the overhang effect on the overhang length according to the rotors with permanent magnet of generators. To examine the phenomenon of overhang effect, the new dynamic analysis method with 2D FEM is suggested and verified by the test results.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1291-1293
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• 2005

Switched reluctance motors have the advantage a high torque/weight ratio, as the large reluctance torque is made by salient poles of both stator and rotor, and a high reliability. On the other hand, the switched reluctance motors have the disadvantage of a large ripple torque which is made by salient poles. So the application for the industrial fields have been limited to special cases. This paper describes the design of a 12/8 switched reluctance motor using a enemy layer method of the asymmetry rotor. The design is focussed to reduce the torque ripple and radial force in the demanded value. The three dimension finite element analysis method(3D-FEM) was used for decides a enemy layer angle of the asymmetry rotor. This paper presents modifications of the rotor pole shape which reduces the torque ripple.

• Steel and Composite Structures
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• v.33 no.4
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• pp.473-487
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• 2019

A shear-deformable finite element model (FEM) with five nodes and thirteen degrees of freedom (DOFs) for free vibrations of laminated composite beams with arbitrary lay-up is presented. This model can be capable of considering the elastic couplings among the extensional, bending and torsional deformations, and the Poisson's effect. Lagrange's principle is employed in derivation of the equations of motion, and thus the element matrices are obtained. Comparisons of the present element's results with those in experiment, available literature and the 3D finite element analysis software (ANSYS(R)) are made to show its accuracy. Some further results are given as referencing for the future studies in vibrations of laminated composite beamst.

• Journal of Korean Port Research
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• v.10 no.2
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• pp.61-68
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• 1996

The main problems in structural analysis by Finite Eelement Method are difficulty in making data file and error estimation. For decreasing these problems' pays. have been suggesting the adaptive mesh refinement and error estimation method. Posteriory error estimation methods suggested by Jang[1], Babuska[2,3], Ohtsubo[8,9], and this paper. Comparing these methods and examine their properties. According this paper, In the problem supposed having singularity, the method suggested by this paper is good, But the problem supposed having no singularity, the method suggested by Jang[1] is good. For decreasing the effect of initial mesh in p-refinement, make application h-refinement at first and apply p-refinement, and confine polynomial's degree to two, for making program simply by plural mesh models are not needed.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.130-143
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• 1995

This paper presents a new methodology for on-line tool breadage detection by sensor fusion of an acoustic emission (AE) sensor and a built-in force sensor. A built-in piezoelectric force sensor, instead of a tool dynamometer, was used to measure the cutting force without altering the machine tool dynamics. The sensor was inserted in the tool turret housing of an NC lathe. FEM analysis was carried out to locate the most sensitive position for the sensor. A burst of AE signal was used as a triggering signal to inspect the cutting force. A sighificant drop of cutting force was utilized to detect tool breakage. The algorithm was implemented on a DSP board for in-process tool breakage detection. Experiental works showed an excellent monitoring capability of the proposed tool breakage detection system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.1-6
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• 2013

Three Surface cracks are among the more common flaws in aircraft and pressure vessel components. Accurate stress intensity analyses and crack growth rate data of surface-cracked components are needed for reliable prediction of their fatigue life and fracture strengths. Three Dimensional finite element method (FEM) was used to obtain the stress intensity factor for surface cracks existing in structures. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Nodes are generated by bucket method, and quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in cylindrical structures subjected to pressure is calculated. Analysis results by present system showed good agreement with those by ASME equation and Raju-Newman's equation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.7
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• pp.945-951
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• 2013

This study evaluated the fatigue strength of the bogie frame of an urban maglev train through fatigue analysis, cumulative damage, and fatigue tests based on a proposed fatigue evaluation method. The results of FEM analysis in which various load combinations were adopted showed that all data were under the fatigue limit of a butt welded joint made of A6005 in a Goodman diagram. The cumulative fatigue damage was calculated at the highest level from a bolt connecting the area of the electromagnetic pole in the casting block; however, the total sum was evaluated as D=0.808 based on $1{\times}10^7$ cycles, which indicates that it did not exceed the failure criteria. In addition, the results of the fatigue testshowed that there was no crack at any position in the bogie frame, which corresponded to the results of fatigue analyses.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.88-94
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• 2012

An axle drive shaft with double joint shaft, cross kit and yoke has an important role by transferring power and changing steering angle between axle and wheel in power train system. It has been used widely in the heavy machinery requiring a high reliability in the power train system. At fatigue failures of the axle drive shaft with the long span, a relatively high stress concentration at a snap ring groove on the drive shaft brings to significant fatigue damages under repeated loading condition. As Peterson's suggestions on this study, a relief groove in the vicinity of the snap ring groove is applied by decreasing the stress concentration and improving the fatigue life of axle drive shaft. By using FEM analysis, the decreasing effect of the stress concentration and extended fatigue life are due to the change of design parameters related with size and location of the relief groove. The relief groove with the design parameters such as d/b=2.0 and r/h=1.2 enables to decrease the stress concentration of 22.3% and increase the fatigue life more than 3 times by comparing with no relief groove application.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.849-851
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• 2000

The value of $I_c$(critical current) in HTS (High Temperature Superconductor) tape has a great influence on $B{\bot}$ (vertical field). Therefore, in shape design of field coil for the HTSG(High Temperature Superconducting Generator), a method to reduce the $B{\bot}$ should be considered in order to maintain the stability and substantial improvement on the performance. On the basis of the magnetic field analysis, this paper deals with various field coil shape to obtain small $B{\bot}$ by using Biot-Savart's law and image method. Moreover the analysis is verified by comparison with experimental results. And also this paper presents the advanced model by using 3D FEM(3 Dimensional Finite Element Method), in which flux density at armature is calculated in 5kVA class HTSG.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.60-69
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• 1999

The noise and vibration sources of rotary compressor for room air-conditioner are pressure pulsation of compression process, cavity resonance of inner space, structural radiation noise of shell and impact noise of discharge valve. Among them, pressure pulsation is very important noise and vibration source. Because it transferred various kinds of noise and vibration like as mentioned above. In this reason, muffler and resonator are used in order to absorb and remove these noises. But an analytical prediction using acoustic analysis does not coincident with the experimental result. The difference between analysis and actual state is due to the assumption of analysis. This paper covered with new concept of muffler design based on the turbulence kinetic energy of flow by using CFD. From this analysis, it is possible to decide the best position of discharge port of muffler. Therefore $2{\sim}3dB$ noise reduction effect is acquired in rotary compressor of 5000 BTU grade. Also new approach of resonator design is suggested. From this study, the characteristics of resonator and surge hole (a kind of resonator without pipe length) are identified. The former is useful for pure tone noise (narrow frequency band), and the latter is effective for broad frequency band. This paper shows that it is very available to use 3 dimensional analysis of resonator in order to predict more exact tuning frequency. The result is proved by a lot of experiments. From combination of fluid analysis and acoustic analysis, up stream position is effective location of resonator concerning turbulence motion of fluid.