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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 25, Issue 12 - Dec 2001
Volume 25, Issue 11 - Nov 2001
Volume 25, Issue 10 - Oct 2001
Volume 25, Issue 9 - Sep 2001
Volume 25, Issue 8 - Aug 2001
Volume 25, Issue 7 - Jul 2001
Volume 25, Issue 6 - Jun 2001
Volume 25, Issue 5 - May 2001
Volume 25, Issue 4 - Apr 2001
Volume 25, Issue 3 - Mar 2001
Volume 25, Issue 2 - Feb 2001
Volume 25, Issue 1 - Jan 2001
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A Study on the Error Compensation of Machine Tool Position Using Reference Artifact and On-Machine Probe
Jo, Nam-Gyu ; Park, Jae-Jun ; Jeong, Seong-Jong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1317~1324
DOI : 10.22634/KSME-A.2001.25.9.1317
In this paper, a methodology of geometrical error identification and compensation for NC machine tool position is developed. We propose a reference artifact with measuring the geometry of coordinate system for compensating linear scale error of NC machine. The coordinate system of the NC machine could be compensated successfully with the information obtained by measuring the reference artifact and our compensation algorithm. Monte Carlo simulation is used to evaluate coordinate referencing ability and, the uncertainties of the machine tool position is estimated and observed through the compensation process by simulation.
Constraint of Semi-elliptical Surface Cracks in T and L-joints
Lee, Hyeong-Il ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1325~1333
DOI : 10.22634/KSME-A.2001.25.9.1325
Critical defects in pressure vessels and pipes are generally found in the form of a semi-elliptical surface crack, and the analysis of which is consequently an important problem in engineering fracture mechanics. Furthermore, in addition to the traditional single parameter K or J-integral, the second parameter like T-stress should be measured to quantify the constraint effect. In this work, the validity of the line-spring finite element is investigated by comparing line-spring J-T solutions to the reference 3D finite element J-T solutions. A full 3D-mesh generating program for semi-elliptical surface cracks is employed to provide such reference 3D solutions. Then some structural characteristics of the surface-cracked T and L-joints are studied by mixed mode line-spring finite element. Negative T-stresses observed in T and L-joints indicate the necessity of J-T two parameter approach for analyses of surface-cracked T and L-joints.
A Study of the Iron-Core Solenoid Analysis for 3 D.O.F. Motor Control with Experimental Method
Baek, Yoon-Su ; Park, Joon-Hyuk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1334~1340
DOI : 10.22634/KSME-A.2001.25.9.1334
In this paper, the experimental modeling of the force between permanent magnet and iron-core solenoid is suggested for more accurate control of 3 D.O.F. motor using the electromagnetic force. In the case of iron-core solenoid, the general equation of solenoid cant be used simply because of its nonlinearity. Therefore, the magnetic flux density is estimated through the concept of equivalent permanent magnet. The force distribution between permanent magnet and iron-core solenoid is more dependent on the magnetization of iron core caused by the permanent magnet than any other parameters. Therefore, the equation of the force estimation between these magnetic systems can be modeled by the experimental function of the magnetization of iron core. Especially, if the distance between iron-core solenoid and permanent magnet is far enough, the force equation through experiment can be expressed from only the current of coil and the distance between iron-core solenoid and permanent magnet. It means that Coulombs law can be used for magnetic systems and it is validated through the experiment. Therefore, force calibration is performed by the concept of Coulombs law.
Design and Control of 3 D.O.F. Spherical Actuator Using the Magnetic Force of the Electromagnets
Baek, Yun-Su ; Yang, Chang-Il ; Park, Jun-Hyeok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1341~1349
DOI : 10.22634/KSME-A.2001.25.9.1341
In this paper, 3 D.O.F. actuator, which has three degrees of freedom in one joint, is proposed. The proposed 3 D.O.F. spherical actuator is composed of the rotor and atator. The upper plate of the stator supports the rotor and five electromagnets are located at the base of the stator. The rotor has two permanent magnets, and each rotational axis of the rotor gimbal system is supported by the bearing. To find out the governing equations for the torque generation, Coulombs law and Lorentz force with respect to magnetism is applied. As the experimental results, if the distance between electromagnet and permanent maget is far enough, the force between these magnets can be expressed from current of coils and z-axial distance. For the purpose of control 3 D.O.F. actuator, PID control law is applied. The experimental results are presented to show the validity of the proposed 3 D.O.F. actuator.
Evaluation of Load-Carrying Capacities for Cracked Pipes
Jang, Yun-Seok ; Kim, Hyeon-Su ; Jin, Tae-Eun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1350~1358
DOI : 10.22634/KSME-A.2001.25.9.1350
During the last decade, a number of experiments and numerical analyses had been performed in conjunction with the development of simplified analytical methods to estimate the fracture behavior of cracked piping in nuclear power plant. However, the necessity of further investigation for the analytical methods was issued because of the discrepancies with the experimental data. The objective of this paper is to find out the optimum methods to evaluate the load-carrying capacities for cracked pipes. To do this, numerous analytical and finite element analyses were carried out for various pipe and crack geometries and materials. These results were synthesized for crack shapes and can be used as basic data for leak before analyses and risk informed inspections.
Measurement of Spindle Thermal Errors in a Machine Tool Using Hemispherical Ball Bar Test
Yang, Seung-Han ; Kim, Gi-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1359~1367
DOI : 10.22634/KSME-A.2001.25.9.1359
Improvement of machine tool accuracy is an essential part of quality control in manufacturing process. Among of all the errors of a particular machine tool, the thermal errors of the spindle have a notably significant effect on machining accuracy and have a direct influence upon both the surface finish and geometric shape of the finished workpiece. Therefore, this paper proposed new measurement method for thermal errors of the spindle in machine tools. The thermal errors are measured by a ball bar system instead of capacitance sensor system. The novel measurement method using ball bar system is more efficient, easier to use than conventional measurement system. And also the ball bar system is possible to measure both geometric errors and thermal errors at the same time.
Application of the Reciprocal Work Contour Integral Method to the Analysis of Eigenvector Cofficients for V-notched Cracks in Anistropic Dissimilar Materials
Jo, Sang-Bong ; No, Hong-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1368~1375
DOI : 10.22634/KSME-A.2001.25.9.1368
This paper examines that it is possible to apply RWCIM for determining eigenvector coefficients associated with eigenvalues for V-notched cracks in anisotropic dissimilar materials using the complex stress function. To verify the RWCIM algorithm, two tests will be shown. First, it is performed to ascertain whether predicted coefficients associated with eigenvectors are obtained exactly. Second, it makes an examination of the state of stresses for FEM and RWCIM according to a number of eigenvectors at a location far away from the v-notched crack tip.
Improvement Scheme of Nodal Integration in Meshless Method
Im, Jang-Geun ; Song, Tae-Han ; Seok, Byeong-Ho ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1376~1383
DOI : 10.22634/KSME-A.2001.25.9.1376
Meshless methods, developed in various ways over the past decade, have been attractive as new computational methods in that they do not need mesh generation in analyzing procedure. But most of these methods were not truly meshless methods because background meshes were required for the spatial integration of a weak form. Accordingly, in this paper, nodal integration for truly meshless methods has been studied, and an improvement scheme is proposed. To improve stabilization and accuracy, which are the weak points in previous nodal integration methods, the integration area is transformed to circle and then numerically integrated. This method does not need any adding term for stabilization in the variational formulation and then simplifies the integration procedure. Numerical test results show that the proposed method is more accurate, stable, and reasonable than the existed nodal integration methods.
Real-Time Forward Kinematics of the 6-6 Stewart Platform with One Extra Linear Sensor
Sim, Jae-Gyeong ; Lee, Tae-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1384~1390
DOI : 10.22634/KSME-A.2001.25.9.1384
This paper deals with the forward kinematics of the 6-6 Stewart platform of planar base and moving platform using one extra linear sensor. Based on algebraic elimination method, it first derives an 8th-degree univariate equation and then finds tentative solution sets out of which the actual solution is to be selected. In order to provide more exact solution despite the error between measured sensor value and the theoretic alone, a correction method is also used in this paper. The overall procedure requires so little computation time that it can be efficiently used for real-time applications. In addition, unlike the iterative scheme e.g. Newton-Raphson, the algorithm does not require initial estimates of solution and is free of the problems that it does not converge to actual solution within limited time. The presented method has been implemented in C language and a numerical example is given to confirm the effectiveness and accuracy of the developed algorithm.
Measurement of the Flying Characteristics of HDD Slider Air Bearing Using AE Signal
Kim, Jae-Jic ; Jeong, Tae-Gun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1391~1399
DOI : 10.22634/KSME-A.2001.25.9.1391
The AE measurement is one of the most convenient methods for detecting contacts between the slider and the disk. The AE method has been widely used in the investigation of the tribology of sliding interfaces due to its convenience. We examined the relationship between the AE signal and the flying height of a slider. We investigated the influence of the disk linear velocity on the AE rms signal by using the AE measurement system. The experiment also gives the relationship between the take-off velocity and the disk surface conditions. To investigate the behavior of the slider further, the variances of the AE signals are analyzed. The experimental results indicate that the increase in the magnitude of the AE rms signal does not necessarily mean the slider/disk contacts.
Non-contact Detection of Ultrasonic Waves Using Fiber Optic Sagnac Interferometer
Lee, Jeong-Ju ; Jang, Tae-Seong ; Lee, Seung-Seok ; Kim, Yeong-Gil ; Gwon, Il-Beom ; Lee, Wang-Ju ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1400~1409
DOI : 10.22634/KSME-A.2001.25.9.1400
This paper describes a fiber optic sensor suitable for non-contact detection of ultrasonic waves. This sensor is based on a fiber optic Sagnac interferometer. Quadrature phase bias between two interfering laser beams in Sagnac loop is introduced by a polarization controller. A stable quadrature phase bias can be confirmed by observing the interferometer output versus phase bias. This method eliminates a digital signal processing for detection of ultrasonic waves using Sagnac interferometer. Interference intensity is affected by the frequency of ultrasonic waves and the time delay of Sagnac loop. Collimator is attached to the end of the probing fiber to focus the light beam onto the specimen surface and to collect the reflected light back into the fiber probe. Ultrasonic waves produced by conventional ultrasonic transducers are detected. This fiber optic sensor based on Sagnac interferometer is very effective for detection of small displacement with high frequency such as ultrasonic waves used in conventional non-destructive testing.
Active Structural Acoustic Control for Reduction of Radiated Sound from Structure
O, Jae-Eung ; Hong, Jin-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1410~1415
DOI : 10.22634/KSME-A.2001.25.9.1410
Active control of sound radiation from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Structural excitation is achieved by two piezoceramic actuators mounted on the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The approach is based on a multi-channel filtered-x LMS algorithm. The results shows that attenuation of sound levels of 11dB, 10dB is achieved.
The Change of Mechanical Properties with Forming Conditions of Thermoplastic Composite in Compression Molding
Lee, Jung-Hui ; Lee, Ho-Eon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1416~1422
DOI : 10.22634/KSME-A.2001.25.9.1416
The objective of this work was to characterize mechanical properties of thermoplastic composites with various forming conditions in compression molding. Randomly oriented long glass fiber reinforced polypropylene(PP) was used in this work. The composite materials contained 20%, 30%, and 40% glass fiber by weight. Compression molding was conducted at various mold temperatures and charge sizes. The temperatures on the mold surface and at the material in the mid-plain were monitored during the molding. Differential Scanning Calorimeter was used to measure crystallinity at both in-side and out-side of the sheet material. Crystallinity at each temperature was also measured by X-ray diffractometer. Dimensional stability was studied at various conditions with the spring forward angle. Among the processing parameters, the crystallization time at the temperature above 130
, was found to be the most effective. Spring-forward angle was reduced and the tensile modulus was increased as the mold temperature increased.
Design Optimization Using Two-Point Diagonal Quadratic Approximation
Choe, Dong-Hun ; Kim, Min-Su ; Kim, Jong-Rip ; Jeon, Jae-Yeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1423~1431
DOI : 10.22634/KSME-A.2001.25.9.1423
Based on the exponential intervening variable, a new two-point approximation method is presented. This introduces the shifting level into each exponential intervening variable to avoid the lack of def inition of the conventional exponential intervening variables due to zero-or negative-valued design variables. Then a new quadratic approximation whose Hessian matrix has only diagonal elements of different values is proposed in terms of these intervening variables. These diagonal elements are determined in a closed form that corrects the typical error in the approximate gradient of the TANA series due to the lack of definition of exponential type intervening variables and their incomplete second-order terms. Also, a correction coefficient is multiplied to the pre-determined quadratic term to match the value of approximate function with that of the previous point. Finally, in order to show the numerical performance of the proposed method, a sequential approximate optimizer is developed and applied to solve six typical design problems. These optimization results are compared with those of TANA-3. These comparisons show that the proposed method gives more efficient and reliable results than TANA-3.
A Study on Synchronously Whirling Motion of Hydrodynamic Journal Bearings
Kim, Gyeong-Ung ; No, Byeong-Hu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1432~1437
DOI : 10.22634/KSME-A.2001.25.9.1432
In this paper, a control algorithm which is synchronously excitating the bearing with whirl speed of rotor is employed to suppress the whirl instability and unbalance response of the rotor-bearing system. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than a conventional analysis with the Reynolds condition. The stabilities and unbalance responses of the rotor-bearing system are investigated for various control gains and phase differences between the bearing and journal motion. It is shown that the unbalance response of the system can be greatly improved by synchronous control of the bearing, and there is an optimum phase difference, which gives the minimum unbalance response of the system, for given operating condition. It is also found that the onset speed of the instability can be greatly increased by synchronous control of the bearing.
A Study on the Development of Large Aluminum Flange Using Casting/Forging Process
Bae, Won-Byeong ; Wang, Sin-Il ; Seo, Myeong-Gyu ; Jo, Jong-Rae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1438~1443
DOI : 10.22634/KSME-A.2001.25.9.1438
The significance of the casting/forging process for reducing the production cost of large components is being noted in these days. This casting/forging process is a method of forging a workpiece preformed by casting into the final shape. In this study, the casting/forging process has been applied in manufacturing a large aluminum flange in order to reduce press capacity and material cost. Firstly, a hot compression test was performed with cast cylindrical billets in order to determine the optimum forging condition of the aluminum flange. The optimum range of forging temperature of Al 5083 was from 420
. The suitable strain rate was 1.5 sec(sup)-1. The deformation amount of a preform of a preform in a forging process is a key role in the mechanical properties of casting/forging products. In order to find the change of mechanical properties according to effective stain of cast aluminum billets, a hot upsetting test were performed with rectangular blocks and then a uniaxial tensile test was performed with specimens cut from the upsetted billets. The tensile strength and the elongation of cast/upsetted aluminum billets were increased largely until the effective strain was 0.7. FE analysis was performed to determine the configurations of case preform and die for an aluminum flange. In the FE analysis, the forging load-limit was fixed 1500ton for low equipment cost. The cast preform was designed so that the effective stain around the neck of a flange exceeded 0.7. From the result of FE analysis, optimal configurations of the cast preform and the die were designed for a large flange. The filling and solidification analysis for a sound cast-preform was carried out with MAGMA soft. In the forging experiment for an aluminum flange, it was confirmed that the optimal configuration of the cast preform predicted by FE analysis was very useful. The cast/forged products using designed preform were made perfectly without any defects.
A Study on the Ranked Bidirectional Evolutionary Structural Optimization
Lee, Yeong-Sin ; Ryu, Chung-Hyeon ; Myeong, Chang-Mun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1444~1451
DOI : 10.22634/KSME-A.2001.25.9.1444
The evolutionary structural optimization(ESO) method has been under continuous development since 1992. The bidirectional evolutionary structural optimization(BESO) method is made of additive and removal procedure. The BESO method is very useful to search the global optimum and to reduce the computational time. This paper presents the ranked bidirectional evolutionary structural optimization(R-BESO) method which adds elements based on a rank, and the performance indicator which can estimate a fully stressed model. The R-BESO method can obtain the optimum design using less iteration number than iteration number of the BESO.
A Proposal of parameter Determination Method in the Residual Strength Degradation Model for the Prediction of Fatigue Life(II)
Kim, Sang-Tae ; Jang, Seong-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1452~1460
DOI : 10.22634/KSME-A.2001.25.9.1452
A new method of parameter determination in the fatigue residual strength degradation model is proposed. The new method and minimization technique is compared experimentally to account for the effect of tension-compression fatigue loading of spheroidal graphite cast iron and graphite/epoxy laminate. It is shown that the correlation between the experimental results and the theoretical prediction on the fatigue life and residual strength distribution using the proposed method is very reasonable. Therefore, the proposed method is more adjustable in the determination of the parameter than minimization technique for the prediction of the fatigue characteristics.
A Nonlinear Model-Based Anti-Swing Control for Overhead Cranes with High Hoisting Speeds
Lee, Ho-Hun ; Jeon, Jong-Hak ; Choe, Seung-Gap ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1461~1467
DOI : 10.22634/KSME-A.2001.25.9.1461
This paper proposes a new approach for the ant-swing control of overhead cranes. The proposed control consists of a model-based anti-swing control scheme and a practical path planning scheme. The anti-swing control scheme is designed based on the Lyapunov stability theorem; the proposed control does not require the usual constraints of small load mass, small load swing, slow hoisting speed, and small hoisting distance, but guarantees asymptotic stability while keeping all internal signals bounded. The path planning scheme is designed based on the concepts of minimum-time control and anti-swing control; the proposed path planning generates near-minimum-time trajectories independently of hoisting speed and distance. The effectiveness of the proposed control is shown by computer simulation.
A Fuzzy-Logic Anti-Swing Control for Three-Dimensional Overhead Cranes
Lee, Ho-Hun ; Kim, Hyeon-Gi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1468~1474
DOI : 10.22634/KSME-A.2001.25.9.1468
In this paper, a new fuzzy-logic anti-swing control scheme is proposed for a three-dimensional overhead crane. The proposed control consists of a position servo control and a fuzzy-logic control. The position servo control is used to control the trolley position and rope length, and the fuzzy-logic control is used to suppress load swing. The proposed control guarantees not only prompt suppression of load swing but also accurate control of trolley position and rope length for the simultaneous travel, traverse, and hoisting motions of the crane. The effectiveness of the proposed control is shown by experiments with a prototype three-dimensional overhead crane.
The Experimental Study of Helical Gear Noise on the Effect of Lead Errors
Park, Chan-Il ; Lee, Jang-Mu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1475~1482
DOI : 10.22634/KSME-A.2001.25.9.1475
Nowadays reduction of gear noise in power transmission is very important, because the noise regulation is severe and demand of customer on noise is increased. To reduce gear noise, it is necessary to understand the noise characteristics of helical gear. In this work, we designed test rig for the study of gear noise and installed in semi-anechoic chamber. By using this rig, sound pressure level is measured under varying rotational speed and torque. The frequency characteristics of helical gear noise on the effect of lead errors and torque are discussed.
A Study on Robust Optimal Design of Laminated Composite Structures with Buckling Constraints
Lee, Byeong-Chae ; Lee, Jeong-Jun ; Jeong, Do-Hyeon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1483~1492
DOI : 10.22634/KSME-A.2001.25.9.1483
A robust optimization procedure is applied to determine the design of the laminated composite plates with buckling constraints. In order to investigate the variation effect to the whole performance of a structure, both design variables and system parameters are assumed as random variables about their nominal values. The robust optimization method has advantages that the mean value and the variation of the performance function are controlled simultaneously and the second order sensitivity information is not required. Considering the information of uncertainty, robust optima for the buckling load of the laminated composite plates with cut-out is obtained. The robustness of the structures is compared to that of the deterministic optimization using scaling factors.
Assessment of Creep Properties of 9Cr Steel Using Small Punch Creep Testing
Yun, Gi-Bong ; Park, Tae-Gyu ; Sim, Sang-Hun ; Jeong, Il-Seok ;
Transactions of the Korean Society of Mechanical Engineers A, volume 25, issue 9, 2001, Pages 1493~1500
DOI : 10.22634/KSME-A.2001.25.9.1493
Recently small punch creep testing (or miniature disc bend creep test) has received much attention through European collaborative research projects. This method was considered as a substitute for the conventional creep rupture testing by which the residual creep life is measured from the specimen taken out from serviced components of high temperature plants. It would be beneficial if the material creep properties such as power law creep constants as well as the creep rupture life can be measured from the small punch creep test. In this paper a method of assessing creep constants from the small punch creep testing is proposed. Finite element analyses were performed to investigate evolution of stress and strain rate at the weakest locations of the small punch creep specimen. Elastic-plastic-secondary creep analyses were carried out. The estimation equations for creep constants by the small punch creep testing are proposed based on the finite analysis results. Small punch creep tests were also performed with 9Cr steel and the accuracy of the proposed equation was verified by the experimental results.