Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
Editor in Chief :
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
Reduction of Wire Sweep during Chip Encapsulation by Runner Balancing and Ram Control
S.J. Han ; Y. J. Huh ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 13~21
In this paper, methods to reduce wire sweep during the chip-encapsulation process have been studide. Two methods have been tried for this purpose, namely runner balancing and ram velocity control. Runner balancing has been achieved automatically by using a computer program. Ram-velocity control has been achieved using empirical rules and results from a flow simulation of the encapsulation process. A mold which has 12 cavities for chip has been used as a case study. The simulation results show that the wire sweep obtained from the optimal process condition is about 1/5 of that from initial, unoptimized condition.
Nonlinear System Modeling Using a Neural Networks
K.T. Chong ; T.S. No ; D.P. Hong ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 22~29
In this paper the nodes of the multilayer hidden layers have been modified for modeling the nonlinear systems. The structure of nodes in the hidden layers is built with the feedforward, the cross talk and the recurrent connections. The feedforward links are mapping the nonlinear function and the cross talks and the recurent links memorize the dynamics of the system. The cross talks are connected between the modes in the same hidden layers and the recurrent connection has self feedback, and these two connections receive one time delayed input signals. The simplified steam boiler and the analytic multi input multi output nonlinear system which contains process noise have been modeled using this neural networks.
Process Monitoring in Laser Beam Cutting by Photo Diode
O.J. Chang ; Kim, B.C. ; Kim, J.D. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 30~37
On-line process control equipment for CO
laser cutting is not available for industrial applications. The major part of the industrial laser cutting machines are adjusted off-line by highly educated engineers. The quality inspection of the sample is visual and referred to different quality scales. Due to the lack of automation the potential laser users hesitate to implement the cutting method. The first step toward an automation of the process is the development of a process monitoring system and the research is cincentrated on the area of on-line quality monitoring during CO
laser cutting. The method is based on the detection of the emitted light from the cutting front by photo diode. The developed monitoring system consists of the OP Amplifier, A/D convertor, power supply and PC. The signal from the photo diode has been undertaken from Fourier analysis and statistical analysis with real time. The photograph of striation pattern was taken by metallurgical microscope. As a result, it is possible to predict the striation pattern according to the beam traveling speed.
An Experimental Study on Grinding Performance and Wear of Alumina Grinding Wheels Developed for High Performance Grinding
K.S. Cho ; Lee, J.C. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 38~45
A new grinding wheel was developed for the high performance grinding of difficult-to-grinding materials. The grinding performance of the newly developed wheel including grinding forces, grinding ratio, and surface roughness of ground surface was evaluated through experiments. Experimental results show that the performance of the newly developed wheel is superior to the conventional alumina wheel and comparable to the Sol-gel wheel. An experimental investigation on the wear of alumina grinding wheel was also carried out. The experiments consist of the measurements of fracture strength of the abrasive grains, grinding force, and the area of wear flats of grinding wheels. Microscopic examination of abrasive grains was executed to observe the progress of wheel wear. The results indicate that the 32A grain, which has relatively lower fracture strength, wears out faster than 5SS and 5SG. The wheel wear occurs much faster in wet grinding than in dry grinding. It has also been found that the grinding forces increase logarithmically with increasing wear flats.
An Experimental Study on Micro Drilling Using Step Feed
Han, J.U. ; Won, J.S. ; Jung, Y.G. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 46~53
Micro drilling is one of the most important machining types and its necessity becomes more and more increasing in the whole field of industry. Micro drilling, however, has few the case of practical application, because it requests high techniques : manufacturing micro drill, treating chip, producting precise hole shape and progressing machining effeciency. Micro drilling has a technical problem: drill breakage from the lack of drill rigdity and the interuption of chip. It is, therefore, essential to select the proper cutting conditions and the step fed for the method solving the lack of rigidity and the interruption of chip. Especially, step feed is very efficient to avoid the breakage of drill, but bring about reducing of cutting efficiency. The study on step feed must be requested more than the present in the near future. The purpose of this paper is to investigate experimentally about cutting conditions which affect on tools and round errors and to estimate about the effect of step feed as well as optimal step feed size to solve the breakage of drill.
Computer Aided Bondgraphs Modeling and Simulation of Hydrostatic Transmission
S.W. Woo ; Park, R.S. ; Lee, J.K. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 54~62
To get the time response characteristics of the hydrostatic transmission, seaborne winch is modelde by using bond graphs. After modeling of its basic elements, it is represented as power flow, and the determination of variable causality. The state equations are derived by using CAMP. As dynamic stabilites and solutions are investigated by perturbation method and direct integration, winch system is stable. Simulations are performed under the conditions of low speed, high speed, and maximum tension. The pressure and flow rate of the hydrostatic transmission have a big overshoot. But when it is comparaed to the empirical data with simulation results, it is similar to each other. When a lead compensator is applied to improve response characteristics of the hydrostatic transmission, rise time and overshoot of the system are improved.
A Study on the Development of a Quality-Driven CIM System (part l: Framework)
M.J. Kang ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 63~69
As the significance of quality in the sense of customer satisfaction is growing, the management of quality becomes one of the main interests in the manufacturing systems research. This paper presents the concept of quality-driven CIM(Computer Integrated Manufacturing) system which is composed of a business process domain and a quality domain. In the business process domain, business functions are integrated by conventional design and manufacturing databases on the one hand, and an integrated quality system is interlinked to them via several quality modules on the other hand. Quality information model connects the business process domain with the quality domain where various types of quality data are stored in the form of quality database. This framework helps a manufacturing enterprise to implement the quality-driven CIM system to achieve its final objective "customer satisfaction".ion".uot;.
A Study on the Fatigue Crack Propagation Behavior of Cr-Mo-V Alloy with Micro Defects at High Temperature.
S.H. Song ; M.S. Kang ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 70~77
Fatigue tests were carried out at high temperature on a Cr-Mo-V steel in order to assess the fatigue life of components used in power plants. The characteristics of high temperature fatigue were divided in terms of cycle-dependent fatigue and time-dependent fatigue, each crack propagation rate was examined with respect to fatigue J-integral range, .DELTA. J
and creep J-integral range, .DELTA. J
. The fatigue life was evaluated by analysis of J-integral value at the crack tip with a dimensional finite element method. The results obtained from the present study are summarized as follows : The propagation characteristics of high temperature fatigue cracks are determined by .DELTA. J
for the PP(tensile plasticity-compressive plasticity deformation) and PC(tensile plasticity - compressive creep deformation) stress waveform types, and by .DELTA. J
for the CP(tensile creep- compressive plasticity deformation) stress waveform type. The crack propagation law of high temperature fatigue is obtained by analysis of J-integral value at the crack tip using the finite element method and applied to examine crack propagation behavior. The fatigue life is evaluated using the results of analysis by the finite element method. The predicted life and the actual life are close, within a factor of 2.f 2.f 2.
A study on the biarc curve fitting of involute curve
Lee, C.M. ; Lee, S.H. ; S.R. Cho ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 78~85
The determination of the optimum biarc curve passing through a given set of points along involute curve is studied. The method adopted is that of finding the optimum no. of span and the optimum length of the span such that the error between the biarc curve and involute curve is minimum. Irregular curve span method is effectively used to describe the involute curve with reduced length of NC-Code.
Step-wise Combinded Implicit/Explicit Finite Element Simulation of Autobody Stamping Processes
D.W. Jung ; D.Y. Yang ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 86~98
An combined implicit/explicit scheme for the analysis of sheet forming problems has been proposed in this work. In finite element simulation of sheet metal forming processes, the robustness and stability of computation are important requirements since the computation time and convergency become major points of consideration besides the solution accuracy due to the complexity of geometry and boundary conditions. The implicit scheme dmploys a more reliable and rigorous scheme in considering the equilibrium at each step of deformation, while in the explict scheme the problem of convergency is elimented at thecost of solution accuracy. The explicit approach and the implicit approach have merits and demerits, respectively. In order to combine the merits of these two methods a step-wise combined implici/explicit scheme has been developed. In the present work, the rigid-plastic finite element method using bending energy augmented membraneelements(BEAM)(1) is employed for computation. Computations are carried out for some typical sheet forming examples by implicit, combined implicit/explicit schemes including deep drawing of an oil pan, front fender and fuel tank. From the comparison between the methods the advantages and disadvantages of the methods are discussed.
Development of Software Interpolators for PC-based NC Machine Tools
M.Y. Yang ; W.P. Hong ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 99~105
Increasing demands on precision machining of free-form surfaces have necessitated the tool to move not only with position error as small as possible, but also with smoothly varying feedrates. In this paper, linear, circular and spline interpolators were developed in reference-pulse type using PC. M-SAM and M-DAM were designed by the comparison and analysis of previous interpolation methods. Spline interpolator was designed to follow the free-form curves. To apply to the real cutting process, constant feedrate compensation and acceleration-deceleration compensation were conceived. Finally, its performance was tested using retrofitted milling machine. As a result, new interpolation algorithm is favorable in precision machining of free-form curves.
A Sliding Mode Control of Robot Manipulator Operated Under the Sea
Park, H.S. ; Park, H.I. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 106~113
This paper presents a modeling of undersea robot manipulators and a control scheme appropriate for manipulating the manipulators working under the unstrcuctured sea water environment. Under the sea, the added mass and added moment of inertia, buoyancy, and drag forces should be considered in modeling the dynamics of the robot manipulators. Due to the complexity of them, the desired dynamics of manipulators can not be accomplished by the conventional control schemes. Hence, a sliding mode control is applied to control the modeling error.
Fracture Behaviour of the AISI 4130 Surface Cracked Plate
J.H. Kim ; J.W. Ong ; S.E. Kim ; S.H. Koo ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 114~119
In the case of surface cracked plate specimen, we can not measure the fracture toughness of ductile materials by the ASTM E 813 standard method. In this report, using the Acoustic Emission method, we found out crack initiation point and investigated fracture toughness which was calculated by FEM. The method used in this paper shows that fracture toughnes by using AE technique is reliable.
Engineered Surface Characterization by Space Series Function
M.S. Hong ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 120~128
An attempt is made to characterize and synthesize engineered surfaces. The proposed method is not only an analytical tool to characterize but also to generate/synthesize three-dimensional surfaces. The developed method expresses important engineered surface characteristics such as the autocorrelation or power spectrum density functions in terms of the two-dimensional autoregressive coefficients.
Dynamic Vibration Absorber Having Coil Springs and Oil Damper for a Damped Vibration System
Ahn, C.W. ; Park, S.C. ; Lee, H.B. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 129~135
This paper presents the effectiveness of the dynamic vibration absorber consisting of a single mass, coil springs and oil damper on the resonance freauency ratio and amplitude ratio for damped linear systems, that is, primary vibration system with damping. The effects of the dynamic vibration absorber are investigated numerically and experimentally for values of mass ratio, natural frequency ratio, and damping ratio. The experimental results show good agreement with calculated ones. As a result, the characteristics shown by the present work are useful in optimal tuning the dynamic vibration absorber in practice.
Experimental Investigation on the Flow Control in Non-Axisymmetric Flat Die Extrusion-1
Bae, W.B. ; Kim, Y.H. ; Park, J.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 136~141
In this paper, the design variables of the extruded parts involving flat die through model experiment are investigated to overcome some current problems such as bending and twisting and get more improved quality products. Above all, the deformation behavior is analyzed in experiment and investigated flow charactristics inside container. Finally, the straight extruded product is obtained by modified bearing land width on the basis of the exit velocities distribution from bended and twisted products.
A Study on Laser Scan Path Generation for Improving the Precision of Stereolithographic Parts
Park, H.T. ; Lee, S.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 142~150
Nowadays, as the development paeiod of new products becomes even shorter, the importance of Rapid Prototyping Technology(RPT) has been rapidly increased. The major application of RPT is an early verification of product designs and quick production of prototypes for testing. Moreover, RPT is applied not only as a second tooling process such as mold making and investment casting but also as a creating some physical structure in medical field. Despite the remarkable progress of RPT, it is required to improve various problems resulting from application such as production time, accuracy and materials. This paper presents a laser scan path generation for accuracy of stereolithographicparts The methodology of laser scan path generation is discussed based on the stereolithography, The procedure of this research is as follows : 1) Input laser scanning conditions such as a laser beam diameter and a laser scanning interval, 2) Reconstruct original contours without self intersecting offset, 3) Calculate offset about reconstructed contours, 4) Calculate intersection points between horizontal or vertical lines and offset contours for internal hatch, 5) Decide laser shutter on/off points. The algorithm developed and programmed by C language is verified as an efficient method after testing a number of STL files of mechanical parts
The Wear Prediction of
-TiC Series Ceramic Tool by Cutting Force Model
Kim, J.S. ; M.C. Kang ; J.S. Jo ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 12, 1996, Pages 151~157
The tool condition monitoring is one of the most important aspects to improve productivity and quality of workpiece. In this study, the wear of ceramic tool (A1
-TiC Series) cutting the hardened die material(SKD11) was investigated. Flank wear was more dominant than crater wear. Therefore the modeling of cutting force related to flank wear has been performed. The cutting force model was construct- ed by an assumption that the stress distribution on the tool face is affected by tool wear. The relationship between characteristics as cutting force and tool wear can be suggested by machining parameters depending on cutting conditions. Experiments were performed under the various cutting conditions to ensure the validity of force models. The theoretical predictions on the flank wear are approximately in good agreement with experimental results.