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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
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Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 13, Issue 12 - Dec 1996
Volume 13, Issue 11 - Nov 1996
Volume 13, Issue 10 - Oct 1996
Volume 13, Issue 9 - Sep 1996
Volume 13, Issue 8 - Aug 1996
Volume 13, Issue 7 - Jul 1996
Volume 13, Issue 5 - May 1996
Volume 13, Issue 4 - Apr 1996
Volume 13, Issue 3 - Mar 1996
Volume 13, Issue 1 - Jan 1996
Selecting the target year
Machine Tool Technology;The Present and the Future(19)
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 13~29
Modeling of Stabilizer for Vehicle Dynamic Analysis
B.K. Cho ; S.J. Song ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 30~35
Tires, bushings and stabilizers are the most difficult elements in vehicle modeling for dynamic analyses. Many studies were performed for tire modeling and the primitive data of bushing elements can be obtained from the suspension designer, but there are few things for stabilizer. This paper presents simulation results for the 3 kinds of stabilizer model with the multi-body dynamic analysis program ADAMS. Each simulation result was compared with the vehicle test result, and the stabilizer model was proposed to analyze the vehicle behaviors precisely.
A Study on the Reliability and Life of the Ravigneaux Planetry Gear Train
Kim, T.H. ; Kim, H.S. ; Yang, S.M. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 36~45
The precise estimation of the reliability and life of the Ravigneaux planetary gear train used in an automatic transmission is necessary in order to enable accurate material and geometric properties to reliability distrobution and the number of load cycles at failure. These are critical for the proba- bilistic design of complex planetary gear system as Ravigneaux type particularly during various gear ratios. The Ravigneaux planetary gear train has five gears, such as a forward and a reverse sun gear, a short and a long pinion, and an annulus gear. In this paper, the Ravigneaux gear system is analyzed to figure out the reliablity distribution. i.e. the probability of survival in the system without its overhaul. First, the reliablity method based on the Weibull distribution is used in conjuction with the Palmgren's model to predict both the individual reliabilities of its components and the nimber of load cycles when the system failed. Then using the presented method, the life of the Ravigneaux gear system can be determined. Alwo the different design parameters such as tooth face width, material property, and Weibull exponent are applied and reached to optimal ones. Thus, the precise evaluation of the reliability and life of the Ravigneaux planetary gear train used in an automatic transmission can be effectively carried out.
A Study on Error Verification of STL Format for Rapid Prototyping System
Park, H.T. ; Lee, S.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 46~55
As industrial standard data, the STL format which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system in recent days. Because most RP system take the only form of two dimensional line segments as an input stream inspite of its imperfectness while converting into STL format, a CAD model is converted into a standard industrial format which is composed of many triangular facets. The error verifying process is composed of four main steps, and these are 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to anedge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Correct the wrong direction and normal vectors. This paper is concerned with serching the mentioned errors in advance and modifying them.
Robust Design of Mechanisms Using the Response Surface Analysis
H.S. Han ; Park, T.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 56~61
In this study a method for a robust design of mechanisms is proposed. The method used in the experimental analysis and quality engineering is applied for mechanisms design. A mathematical model for a mechanism is estimated by the response surface analysis and the estimated model is used in minimization of the variance. Using this result, robust design can be carried out. The method can be applied for general mechansims. Furthermore because the method can be used in the design stage using the computer model, improved quality and lower cost of the product is achieved even in the design stage.
The Prediction of the Cutting Characteristics in Cryogenic Cutting Using Neural Network
Kim, C.S. ; S.Y. Oh ; S.S. Oh ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 62~70
We experimented on cutting characteristics-cutting force, behavior of cutting temperature, surface roughness. chip thickness under low temperature, which generated by liquid nitrogen(77K). The work-pieces were freezed to-195 .deg. C and liquid nitrogen was also sprinkled on cutting area in order to decrease an experimental error of machining in low temperature. The workpiece was became to -195 .deg. C in5 minutes. In cooled condition surface roughness of workpiece was better than normal condition. In addition, we investigated the possibility that surface roughness of workpiece and cutting force can be predicted analyzing cutting conditions by the trained neural network.
The Development and Evaluation of OMM(On the Machine Measuring) System Using Scanning Probe
Kim, S.H. ; Kim, I.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 71~77
This paper describes the development of on the machine measuring(OMM) system which can directlry measure the three dimensional machined dimensilnal accuracy using scanning probe in milling machine. Two algolithms, continuous path(CP) measurement using UC program and CAD data assisted point to point(PTP) measurement, were developed regarding specification of scanning probe. The OMM system was contructed to verify the developed system suing the proposed algorithm, and actually measured three kinds of machined TV shadow mask molds. The developed system was evaluated it's repeatability and compared with the current measurement system of CMM(Coording Measuring Machine) in terms of relative accuracy and time reduction and productivity increase.
A Remeshing Criterion for Large Deformation Finite Element Analysis
H.G. Cho ; S.W. Cha ; Park, J.J. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 78~87
In this paper, a remeshing criterion has been suggested in order to order to automate the remeshing decision during finite element analysis of metal forming. In order to use for the remeshing decision, two of remeshing criteria have been investigated. One is the use of error estimates based on errors in stresses and strain rate of the finite element solution and the other is the use of geometric characterisreics of distorted elements. As a result, the strain rate error estimate in power norm based on the former is found to give more valuable information about remeshing decision than the ones based on the latter. Examples are given to demon- strate the usefulness of the suggested eroor estimate as a remeshing criterion.
A Study on the Design and Control Super-Precision Coarse and Fine Positioning Apparatus
Kim, J.Y. ; Cho, Y.T. ; O, S.M. ; Park, K.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 88~93
The study was carried out development a pricision positioning apparatus, consisting of DG servo motor and piezoelectric actuatior. This system is composed of fine and coarse apparatus, measurement system and control system. Peezoelectric actuator is designed for fine positioning. Coarse positioning using lead screw is droved by DC servo motor. Control system output a signal from laser interfermeter and capacitive sensor to amplifer of DC servo motor and piezoelectric actuator after digital signal processing (DSP). Resolution of this apparatus measure with laser interferometer and microsense
Design of a real time adaptive controller for industrial robot using TMS320C31 chip
S.H. Han ; Y.T. Kim ; S.K. Kim ; J.O. Kim ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 94~104
This paper presents a new approach to the design of adaptive control system using DSPs(TMS320C31) for robotic manpulators to achieve accurate trajectory tracking by the joint angles Digital signal processors are used in implementing real time adaptive control algorithms to provide an enhanced motion control for robotic manipulators. In the proposed contorl scheme, adaptation laws are derived from the improved Lyapunov second stability analysis method based on the adaptive model reference control theory. The adaptive controller consists of an adaptive feedforward controller, feedback controller, and PID type time varying auxillary control elements. The proposed adaptive control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Morever, this scheme does not require an accurate dynamic modeling nor values of manpipulator parameters and payload. Performance of the adaptive controller is illustated by simulation and experimental results for a SCARA robot.
The Prediction of Geometrical Configuration and Ductile Fracture Using the Artificial Neural network for a Cold Forged Product
Kim, D.J. ; Ko, D.C. ; Park, J.C. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 105~111
This paper suggests the scheme to simultaneously accomplish prediction of fracture initiation and geomeytical configuration of deformation in metal forming processes using the artificial neural network. A three-layer neural network is used and a back propagation algorithm is adapted to train the network. The Cookcroft-Lathjam criterion is used to estimate whether fracture occurs during the deformation process. The geometrical configuration and the value of ductile fracture are measured by finite element method. The predictions of neural network and numerical results of simple upsetting are compared. The proposed scheme has successfully predicted the geometrical configuration and fracture initiation.
An Expert System Using Diagnostic Parameters for Machine tool Condition Monitioring
D.S. Shin ; S.C. Chung ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 112~122
In order to monitior machine tool condition and diagnose alarm states due to electrical and mechanical faults, and expert system using diagnostic parameters of NC machine tools was developed. A model-based knowledge base was constructed via searching and comparing procedures of diagnostic parameters and state parameters of the machine tool. Diagnostic monitoring results generate through a successive type inference engine were graphically displayed on the screen of the console. The validity and reliability of the expert system was rcrified on a vertical machining center equipped with FANUC OMC through a series of experiments.
Robust Trajectory Control of Direct Drive Manipulator based on combining
Controller and Computed Torque Method
Kim, C.K. ; Kang, B.S. ; Kwak, Y.K. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 123~129
Computed torque method has been used for precise trajectory control of the robotic system that involves nonlinear dynamics. It is hard to know exact values of robot system parameters, and the robot arm receives umpredictable interference from the working environment. These disturbances, especially in a direct drive robot, are directly transmitted to actuating motor without reduction. Modelling error and distrubance can cause significant errors in a trajectory tracking problem. In this paper, we propose a new controller that
controller is conbined to robot system linearized by computed torque. Simula- tions are made for comparing the performance of the proposed controller with that of a nonlinear
controller proposed by Chen and also computed torque method.hod.
A study on the damage process of fatigue crack growth using the stochastic model
W.S. Lee ; K.S. Cho ; H.W. Lee ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 130~138
In general, the scattler is observed in fatigue test data due to the nonhomogeneity of a material. Consequently. It is necessary to use the statistical method to describe the fatigue crack growth process precisely. Bogdanoff and Kozin suggested and developed the B-model which is the probabilistic models of cumulative damage using the Markov process in order to describe the damage process. But the B-model uses only constant probability ratior(r), so it is not consistent with the actual damage process. In this study, the r-decreasing model using a monotonic decreasing function is introduced to improve the B-model. To verify the model, thest data of fatigue crack growth of A12024-T351 and A17075-T651 are used. Compared with the empirical distribution of test data, the distribution from the r-decreasing model is satisfactory and damage process is well described from the probabilistic and physical viewpoint.
A Combined Bearing Arrangement for High Damping Spindle Systems
Lee, C.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 139~145
The machining accuracy and performance is largely influenced by the static, dynamic and thermal characteristics of spindle systems in machine tools, because the spindle system is a intermedium for cutting force from tool and machine powef from motor. Large cutting force and power are transmitted by bearing with a point or line contact. So, the spindle system is the static and dynamic weakest point in machine structure. For improvement of static stiffness of spindle system can be changed design parameters, such as diameter of spindle, stiffness of bearing and bearing span. But for dynamic stiffness, the change of the design parameters are not useful. In this paper, the combined bearing arrangement is suggested for high damping spindle system. The combined bearing arrangement is composed of tandem double back to back arrangement type ball bearins and a high damping hydrostatic bearing. The variation of static deflection and amplitude in first natural frequency is evaluated with the location of hydrostatic bearing between front and rear ball bearing. The optimized location of hydrostatic bearing for high static and dynamic stiffness is determined rapidly and exactly using the mode shape and transfer function of spindle. The calculation of damping effect on vibration by unbalance of grinding wheel and pulley in optimized spindle system is carried out to verify the validity of the combined bearing arrangement. Finally, the simulation of grinding process show that the surface roughness of workpiece with high damping spindle system is 60% better than with ball bearing spindle system.
Collocated Capacitance Sensor Design for Magnetic Bearing Control
D.W. Shin ; Kim, J.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 146~153
This paper presents the development of a collocated capacitance sensor and its application to the controller design for magnetic bearing supported rotor systems. The main feature of the sensor is that it is made of a compact printed circuit board(PCB) so that it can be built into the actuator coil of the magnetic bearing unit. The singnal processing unit hax been also developed. The experi- mental results of the sensor performance evaluation on sensitivity, bandwidth and resolution are presented. Then, simulation study shows the advantages of the collocated sensor for magnetic bearings over the nonco- llocated sensor. Finally, the experimental result on the performance of the collocated sensor based contrl- ler for a magnetic bearing rotor system is presented.
Admittance Model-Based Nanodynamic Control of Diamond Turning Machine
S.H. Jeong ; Kim, S.S. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 10, 1996, Pages 154~160
The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface cnotours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated dapth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in additn to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamoneter. Based on the parameter estimation of cutting dynamics and the admitance model-based nanodynamic control scheme, simulation results are shown.