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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 10, Issue 3 - Sep 1993
Volume 10, Issue 2 - Jun 1993
Volume 10, Issue 4 - Mar 1993
Volume 10, Issue 1 - Mar 1993
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New Technology and Future Trend in Digital Control
H.K. Sung ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 7~15
This paper introduces a new concept to analyze the digital control system where the continuous-time plant is stabilized by the digital controller with sampler and hodl. It gives some methods to handle the inter-sampling behavior which has not been considered in the digital controller design. Also, the new trend and future direction in digital control are introduced.
Flexible inspection system using CAD detabase and vision guided coordinate measuring machine
M.W. Cho ; Park, Y.K. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 16~29
The objective of this research is in the development of a flexible 3-dimensional inspection system for the sculptured surface by integrating the Coordinate Measuring Machine (CMM), CAD database, and vision system. To achieve the proposed flexible inspection system, two research categories are discussed in the study: new inspection planning method includes a new measuring point selection method and various new probe path generation methods. The object recognition and localization process for the unknown surface can be easily carried out by introducing a new concept called "Z-Layer". The experimental results indicate that the developed flexible inspection system, with the proposed algorithm, can be inplemented in real situation.situation.
A Feature Based Modeling System for the Design of Welded Plate Construction
Kim, D.W. ; S.M. Yang ; Park, J.S. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 30~41
Developed in this paper is a feature based modeling system for the design of welded plat construction(WPC) which is composed of flat or bended plates represented as reference plane with a constant thickness. First, the necessity and the characteristics of the modeing system for WPC as compared with the assembly of mechanical parts are investigated. Secondly, feature library for the assembly of WPC is shown which contains several types of features like joint feature, groove feature, material feature, and precision feature. Thirdly, the assembly procedures are presented which mainly consist of both the assembly transformation and the correct assembly checking. Fourthly, weld lines of the assembled WPC are defined so that those can be used in the process planning or the manufacturing stage. Finally, a prototype by a geometric modeling software Pro/Engineer, a graphic software GL(Graphic Library), and C language on a CAD workstation IRIS.
The Optimum Design of A 6 D.O.F Fully-Parallel Micromanipulator for Enhanced Robot Accuracy
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 42~53
Elastodynamic Control of Industrial Robotic Manipulators Using Piezoelectric Materials
Park, S.B. ; C.C. Cheong ; Lee, T.H. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 54~63
This paper presents the dynamic modeling and control methodology to arrest structural deflections of industrial robotic manipulators featuring elastic members retrofitted with surface bonded pizoelectric actuators and sensors. The cynamic modeling is accomplished by employing a variational theorem, prior to developing a finite element formulation. This finite element formulation accounts for both original robot member elements and also bonded piezoelectric material elements. The governing equation of motion is then modified by condensing the electric potential vectors and subsequently two different negative velocity feedback controllers are established; a constant-gain feedback controller and a constant- amplitude feedback controller. By adopting a Model P50 articulating industrial robot manufactured by Gerneral Electric Company, conputer simulations are underlaken in order to demonstrate superior performance characteristics to be accrued from this proposed methodology such as smaller deflections at the end-effector.
A Study on the Effect of Beam Mode on the Size of Hardened Zone in Laser Surface Hardening
Kim, J.W. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 64~72
Analytical models for the prediction of the size of hardened zone in laser surface hardening are presented. The models are based on the solutions to the problem of three-dimensional heat flow in plates with infinite thickness. The validity of the model was tested on medium carbon steel for Gaussian mode of beam. Then the model for rectagular beam was used for the predicition of the size of hardened zone on various hardening process parameters. From the calculation results it appeared that the size and shape of the hardened zone are strongly dependent on process parameters such as beam mode, beam size, and traverse speed.
Cutting Force Control by Variable Feed and Spindle Speed in Ball-end Milling Process
Lee, C.H. ; S.U. Yi ; Lee, G.B. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 73~80
There and two important variables in machining process control, which are feed and cutting speed. It is possible to improve the machining accuracy and the productivity by maintaining the optimal feed and cutting speed. In this work, a controller is designed to achieve on-line cutting force control based on the modeling of cutting process dynamics established through step response test. Two schemes are proposed and implemented. The first is feed control under the constant spindle speed and the second is spindle speed control under the constant feed. Finally, both are proved to work properly through simulation and experimentation.
3D Shape Reconstruction from 2D Cross-Sections
Park, H.J. ; Kim, K.S. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 81~93
The three dimensional(3D) shape reconstruction from two dimensional(2D) cross-sections can be completed through three main phases : the input compilation, the triangular grid formation, and the smooth surface construction. In the input compilation phase, the cross-sections are analyzed to exctract the input data required for the shape reconstruction. This data includes the number of polygonized contours per cross-section and the vertices defining each polygonized contour. In the triangular grid formation phase, a triangular grid, leading to a polyhedral approximations, is constructed by extracting all the information concerning contour links between two adjacent cross- sections and then performing the appropriate triangulation procedure for each contour link. In the smooth surface construction phase, a smooth composite surface interpolating all vertices on the triangular grid is constructed. Both the smooth surface and the polyhedral approximation can be used as reconstructed models of the object. This paper proposes a new method for reconstructing the geometric model of a 3D objdect from a sequence of planar contours representing 2D cross-sections of the objdect. The method includes the triangular grid formation algorithms for contour closing, one-to-one branching, and one-to-many braanching, and many-to-many branching. The shape reconstruction method has been implemented on a SUN workstation in C.
Tool Wear Monitoring Scheme by Modeling of the Cutting Dynamics by Time-series Method
W.T. Kwon ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 94~103
In this work, the imaginary part of the inner modulation transfer function of the cutting dynamics is introduced for tool wear monitoring. Time-series method is utilized to construct the general three dimensional cutting dynamics whose imaginary part of the inner modulation transfer funcition shows the proportionality to tool wear at the natural frequency of the machine tool dynamics. Thus model is reduced to single-input single-output model without altering the proportionality characteristics to tool wear and implemented to the dual computer system in which one computer performs measurement while the other calculates the imaginary part of the inner modulation transfer function of the cutting dynamics by the batch least square method. The values of the imaginary part at the natural requency of the machine tool structure in the cutting direction are compared to the one calculated during machining with a brand new tool to decide the current status of the tool. The experiments shows the relevance of the proposed concept.
Development of linear measuring system
T.B. Eom ; Kim, G.Y. ; M.S. Chung ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 104~108
The linear length measurements are most frequently performed and should be most accurate among other parts in dimensional metrology. We developed the linear measuring system using a laser interferometer to improve the accuracy and to shorten the calibration time. The uncertainty of the system is 0.01 .mu. for 500mm steel gage block. The range of the measurement and resolution of the system are 1000mm and 0.01 .mu. m, respectively.
The Incipient Deformation Analysis for Plane Strain Open-Die Forging Processes with V-shaped Dies Using the Force Balance Method
Lee, J.H. ; Kim, B.M. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 109~117
Force balance method is employed to predict forging information such as forging load, tool pressure and normal stress at the surface of tangential velocity discontinuity. The incipient stages of deformation for the plane strain forging of rectangular billets in V-shaped dies of different semi-angles are analysed. To construct an approximate model for the analysis of deformation by the force balance method in the incipient deformation stages, slip-line field is used. When the deformation mode by slip-line method is the same as that by force balance method, the slip-line method and the force balance method give identical solutions. The effects of die angle, coefficient of friction, billet geometries and deforma- tion characteristics are also investigated. In order to verify the validity of force balance analysis, the rigid-plastic finite element simulation for the various forgig parameters are performed and performed and find to be in good agreement.
QLQG/LTR Depth Control System Design for Underwater Vehicles
Kim, J.S. ; S.I. Han ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 118~127
A nonlinear control design method called the QJQG/LTR method is presented for the depth control of underwater vehicles with the deadzone of the flow control valve. And, it is shown how the design plant model can be formulated in the QLQG/LTR depth control system design for underwater vehicles which have the triple integrator. In order to show the effectiveness of this control system, the linear LQG/LTR control system neglected the deadzone effect and the nonlinear QLQG/LTR control system considered it are compared. It is found that the QLQG/LTR control system is relatively insensitive to the input magnitude, even if there exists a hard nonlinearity in the plant.
A study on rolling materials and work roll wear in the cold rolling
E.C. Jeon ; Kim, S.K. ; Kim, M.K. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 128~134
Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions and lubrication. The tests were performed to find the effects of rolling materials under the same lubrication conditions. The obtained results are as follfws; 1) The decrease in surface roughness of work roll is more rapid in that case of continuously cast A1-killed steel strip than ingot cast steel strip. In rolling of continuously cast A1-killed steel strip, worn powder rich in A1
3/sticks to the work roll surface, and so it makes the mirror surface of work roll accelerate. 2) Amount of work roll wear is small in rolling of continuously cast A1-killed strip. 3) In rolling of continously cast A1-killed steel strip, it is necessary to put up the intial surface roughness of work roll in order to prevent work roll slip.
Analusis of Strain Rate Distribution using Fourier Transform Grid Method
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 135~141
Development of a Multiple Monitioring System for Intelligence of a Machine Tool -Application to Drilling Process-
Kim, H.Y. ; J.H. Ahn ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 142~151
An intelligent mulitiple monitoring system to monitor tool/machining states synthetically was proposed and developed. It consists of 2 fundamental subsystems : the multiple sensor detection unit and the intellignet integrated diagnosis unit. Three signals, that is, spindle motor current, Z-axis motor current, and machining sound were adopted to detect tool/machining states more reliably. Based on the multiple sensor information, the diagnosis unit judges either tool breakage or degree of tool wear state using fuzzy reasoning. Tool breakage is diagnosed by the level of spindle/z-axis motor current. Tool wear is diagnosed by both the result of fuzzy pattern recognition for motor currents and the result of pattern matching for machining sound. Fuzzy c-means algorithm was used for fuzzy pattern recognition. Experiments carried out for drill operation in the machining center have shown that the developed system monitors abnormal drill/states drilling very reliably.
Impact damage and residual bending strength of CFRP composite laminates involved difference of fiber stacking orientation and matrics
J.K. Sim ; I.Y. Yang ; T.Y. Oh ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 152~162
The purpose of this study is to investigate problems of residual bending strength and the impact damage experimentally when CFRP composite laminates are subjected to Foreign object damage. The specimens composed of four types of CR/EPOXY and a CF/PEEK composite laminates which involved difference of fiber stracking orientation and matrics. The result were summariged as follows : 1) It is found that both orthotropic and guasi-isotropic composite laminates are increasimg lineally between impact energy and damage delamination area. 2) Delamination devel- opment energy(mm
J) OF cf/epoxy composite aminates is less than that of CF/PEEK. 3) When impact energy is applied to specimens within 3J, the residual strength of orthotropic is greater than guasi-isotropic composite laminates. On the other hand, it is predicted that residual bending strength of orthotropic composite laminates is less than that of quasi-isotropic when impact energy is more thaen 3J. 4) It is found in CF/PEEK that for the impact side compression, residual of bending strength versus impact energy is almost constant, while in case of impact side tension, residual bending strength is decreased rapidly near 1.2J. of impact energy due to the effect of delamination buckling.
Vibration Control of Flexible Manipulator
K.H. Bae ; Lee, J.W. ; H.H. Joo ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 163~169
A flexible manipulator can move in the high speed even with the small driving torque. The dymanic equations of flexible manipulator which include 2 vibrational modes are derived using the clamped-free boundary condition. Simulation results of the 6th order model are well matched with experimental results. The hub angle of the flexible mainpulator can be controlled without vibration of the beam by the feedback of both hub angle and strain. The overshoot of the hub angle in the step response is reduced without sacrificing the rise time using the cycloidal function instead of the step function as the referenmce input.
A study on correspondence problem of stereo vision system using self-organized neural network
Y.B. Cho ; D.G. Gweon ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 170~179
In this study, self-organized neural network is used to solve the vorrespondence problem of the axial stereo image. Edge points are extracted from a pair of stereo images and then the edge points of rear image are assined to the output nodes of neural network. In the matching process, the two input nodes of neural networks are supplied with the coordi- nates of the edge point selected randomly from the front image. This input data activate optimal output node and its neighbor nodes whose coordinates are thought to be correspondence point for the present input data, and then their weights are allowed to updated. After several iterations of updating, the weights whose coordinates represent rear edge point are converged to the coordinates of the correspondence points in the front image. Because of the feature map properties of self-organized neural network, noise-free and smoothed depth data can be achieved.
Formulating 3-dimensional modeling from the orthographic projection drawing using feature recognition technique.
Lee, S.H. ; K.S. Bahn ; Lee, H.K. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 180~189
In CAD/CAM system, it is required to produce manufacturing information from the deawing output of design system. The most difficult task is to formulate 3-dimentional modeling information utilizing 2-dimentional data. This paper addresses the automatic converting steps of 2-dimentional drawing data to 3-dimentional solid modeling using feature recognition rules as an expert shell. With the standardization of design process and recognition rule as a fundamental steps, the developed system shows a good application tool which can interface the design and manufacturing stage in CAD/CAM system of PC level.
Real time control of a mobile robot considering dynamics
Y.Y. Cha ; D.G. Gweon ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 190~199
In this study a three-axes mobile robot which has two independently controlled driving wheels and a function of simultaneously steering the driving wheels has been developed. Two-motion modes of the mobile robot, the first is a differential velocity motion of two driving wheels and the second is a equal driving and steering motion, have been analyzed and the kinematic and dymanic analyses about the each motion mode have been carried out. As a result of dynamic analysis, the torque used on a motor control and acceleration have been derived explicitly. Hence, a computation time is saved effectively and a real time control of the mobile robot considering the dynamics has become possible. Through a simulation the results considering the dynamics have been compared with that no regarding the dynamics and the possibility of real-time control has been proved.
A study on the design and control of an articulated hand
Kim, C.W. ; D.G. Gweon ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 200~205
In many applications, the typical parallel-jaw end-effector of a robot arm has been remarkably satisfactory. But, it is not adequate for the applications such as complicated manipulation. In the study, a finger with 4 joints (so, having redundancy) was consturcted to investigate the characteristics of an articulated hand. Each joint was driven by one actuator, and the motor torque was transmited to each joint through a tendon-pulley system. In the context, major considerations for hardware design and the method to solve the inverse kinematics of a redundant manipulator were presented. Finally, the basic capabilities of an articulated hand were presented through experiments.
A study on the effect of cutting parameters of micro metal cutting mechanism using finite element method
J. Hwang ; S. Namgung ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 206~215
The finite element method is applied to analyze the mechanism of metal cutting, especially micro metal cutting. This paper introduces some effects, such as constitutive deformation laws of workpiece material, friction of tool-chip contact interfaces, tool rake angle and also simulate the cutting process, chip formation and geometry, tool-chip contact, reaction force of tool. Under the usual plane strain assumption, quasi-static analysis were performed with variation of tool-chip interface friction coefficients and tool rake angles. In this analysis, cutting speed, cutting depth set to 8m/sec, 0.02mm, respectively. Some cutting parameters are affected to cutting force, plastic deformation of chip, shear plane angle, chip thickness and tool-chip contact length and reaction forces on tool. Several aspects of the metal cutting process predicted by the finite element analysis provide information about tool shape design and optimal cutting conditions.
A study on the chatter vibration of two degree of freedom systems
Kim, J.S. ; M.C. Kang ; Kim, B.R. ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 216~226
Three dimensional cutting is considered as an equivalent orthogonal cutting through the plane containing both the cutting velocity vector and the chip flow velocity vector in dynamic cutting process. An analytical expression of dynamic cutting force is obtained from the cutting parameters determined by the static cutting. Particular attention is paid to the energy supplied to the vibratory system of cutting tool with two degree of freedom. In this approach, the phase lag of the horizontal vibration of the tool behind the vertical vibration and the direction angle of the fluctuating cutting force is considered in point of stability limits. Chatter vibration can be effectively suppressed by relatively increasing the spring constant and the damping coefficient of the cutting system in the vertical cutting force direction. A good agreement is found between the stability limits predicted by theoretical value and experimental results.
Development of high performance universal contrller based on multiprocessor
Park, J.Y. ; P.H. Chang ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 227~235
In this paper, the development of a high performance flexible controller is described. The hardware of the controller, based on VME-bus, consists of four M68020 single-board computers (32-bit) with M68881 numerical coprocessors, two M68040 single board donputers, I/O devices (such as A/D and D/A converters, paraller I/O, encoder counters), and bus-to-bus adaptor. This software, written in C and based on X-window environment with Unix operating system, includes : text editor, compiler, downloader, and plotter running in a host computer for developing control program ; device drivers, scheduler, and mathemetical routines for the real time control purpose ; message passing, file server, source level debugger virtural terminal, etc. The hardware and software are structured so that the controller might have both flexibility and extensibility. In papallel to the controller, a three degrees of freedom kinematically redundant robot has been developed at the same time. The development of the same time. The development of the robot was undertaken in order to provide, on the one hand, a computationally intensive plant to which to apply the controller, and on the other hand a research tool in the field of kinematically redundant manipulator, which is, as such, an important area. By using the controller, dynamic control of the redundant manipulator was successfully experimented, showing the effectiveness and flexibility of the controller.
Automated design module generation system for parametric design
Lee, S.H. ; K.S. Bahn ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 236~247
An davanced method for the automatic generation of parametric models in computer- aided design systems is required for most of two-dimensional model which is represented as a set of geometric elements, and constraining scheme formulas. The development system uses geometric constraints and support of topology parameters from feature recognition and grouping the design entities into optimal ones from pre-designed drawings. The aim of this paper is to present guidelines for the application and development of parametric design modules for the standard parts in mechanical system, the basic constitutional part of mold base, and other 2D features.
A study on vision algorithm for bin-picking using labeling method
Park, J.W. ; Park, K.T. ; G.J. Chung ;
Journal of the Korean Society for Precision Engineering, volume 10, issue 4, 1993, Pages 248~254
This paper proposes the labeling method for solving bin-picking problem in robot vision. It has the processing steps such as image thresholding, region labeling, and moment computation. To determine a target object from object, the modified labeling method is used to. The moment concept applied to determine the position and orientation of target object. Finally, some experiment result are illustrated and compared with the results of conventional shrinking algorithm and collision fronts algorithm. The proposed labeling method has reduced processing time.