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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 14, Issue 12 - Dec 1997
Volume 14, Issue 11 - Nov 1997
Volume 14, Issue 10 - Oct 1997
Volume 14, Issue 9 - Sep 1997
Volume 14, Issue 8 - Aug 1997
Volume 14, Issue 7 - Jul 1997
Volume 14, Issue 6 - Jun 1997
Volume 14, Issue 5 - May 1997
Volume 14, Issue 4 - Apr 1997
Volume 14, Issue 3 - Mar 1997
Volume 14, Issue 2 - Feb 1997
Volume 14, Issue 1 - Jan 1997
Selecting the target year
The Study on Improvement of Shape Accuracy in Stereolithography
Kim, J.A. ; I.H. Paik ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 15~21
In the stereolithography process, the accuracy of cured shape depends on laser power, scanning speed, scanning pattern, resin characteristics etc. When three-dimensional objects are built, higher laser power gives higher building efficiency. Normally we could control scanning speed and scanning pattern, which affect curing thickness and generate volume of curl in & after building. Olgomer, Monomer and Initiator are major components. Kinds and volume of them decide characteristic of resin. In this paper, we deal with major facts and their characteristics for precision shape building.
An Automated Die Design System for Blanking and Piercing of Stator and Rotor Parts
Park, J.C. ; Kim, B.M. ; Kim, C. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 22~33
This paper describes a research work of developing a computer-aided design of blanking and piercing for stator and rotor parts. Based on knowledge-based rules, the die design system, STRTDES2, is designed by considering several factors, such as complexities of blank geometry and punch profile, and availability of press equipment and standard parts. Therefore this system can carry out a die design for each process which is obtained from the result of an automated process planning system, STRTDES1 and generate part drawing and the assembly drawing of die set in graphic forms. Knowledges for die layout are extracted from plasticity theories, relevant references and empirical know-hows of experts in blanking industries.
Development of a Measurement System for Axial-symmetric Objects Using Vision Sensor
Lee, S.R. ; Kim, C.S. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 34~41
The dimension measurement problem of products has been a major concern in the quality control in the industrial fields. A non-contacting measurement system using the vision sensor is proposed in this paper. The system consists of a CCD camera for the image capture, a frame grabber for the acquired image processing, a laser unit for the illumination, scanning unit for the measurement, and a personal computer for the geometry computation. The slit beam which is generated by passing the laser beam through a cylin- drical lens is fired to the axial-symmetric object on the rotating plate. The image of objects reflected by the laser slit beam, acquired by the CCD camera, becomes much brighter than the other parts of objects. After the histogram of brightness for the captured image is calculated, low intensity pixels are filtered out by threshold method. The performance of proposed measurement system is obtained for several different axial symmetric objects. The proposed system is verified as a good tool for measuring axial-symmetric parts in a limited condition with a minor investment cost.
Automatic Offline Teaching of Robots for Ship Block Welding Applications
S.G. Lim ; J.S. Choi ; Y.S. Han ; J.H. Borm ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 42~52
Computer aided process planning and Offline programming are decisive factors in successful implementation of automated robotic production. However, conventional offline programming procedure has proven ineffective due to time-consuming teaching process for robot programming and due to inefficient system modeling. The paper presents an efficient procedure to semi-automatically generate robot job programs for ship block welding applications. In the research, the teaching positions are automatically determined by predefined rules which are functions of the type and the dimensions of the given welding section of ship block. And a sequence of robot movements and welding conditions such as welding type, welding current, welding speed, and welding torch orientation, are determined by use of Standard Program which is experimentally proved to work well for the welding wection group. Finally, a robot program for the welding section is generated automatically. Based on the algorithm, a offline automatic teaching software is developed. The paper presents also the algorithm and structure of the software.
Influence on EDM Surface with the Copper and Graphite Electrode According to the Discharge Energy
Park, J.Y. ; E.C. Jeon ; J.H. Jeong ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 53~59
This study has been performed to inmvestigate MRR(metal removal rate), REW(relative electrode wear), surface roughness, heat transumutation layer and microhardness distribution in cross-section of the machined surface with various pulse-on duration and peak pulse current, using the copper and graphite electrode on the heat treated STD11 which is extensively used for metallic molding steel with the EDM. The results obtained are as follows; a) There exists critical pulse-on duration(If Ip equals 5A, .tau. on is 50 .mu. s) which shows the the maximum MRR in accordance with peak oulse current and the MRR decreases when the pulse-on duration exceeds the critical pulse-on during because of the abnormal electric discharge. b) Safe discharge is needed to make maximum of MRR and the metalic organization must be complicated for discharge induction. c) Graphite has much more benefits than copper electrode when rapid machining is done without electrode wear. d) The most external surface has the highest microhardness because of car- burizing from heat analysis of the dielectric fluid and the lower layar of the white covered layer has lower microhar dness than base matal because of softening.
A New Profilometry System for Precision Measurement of 3D Shape Using the Directional Magnification Control of a Laser Light Stripe
Park, S.K. ; S.H. Baik ; Kim, C.J. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 60~65
This paper proposes a profilometry system for precise surface contouring of 3D objects using a direc- tionally magnified image of a laser light stripe. The resolution of this system can be improved several times comparad with that of conventional systems without loss of spatial resolution and depth of measurement. A pair of cylindrical lens(a convex lens and a concave lens) are used for a directionally magnified image of a laser light stripe maintaining the same focal plane. Also, image processing procedures for image reconstruc- tions are described.
Development of a Fuzzy Fault Diagnosis System in Variable Speed Rotating Shafts
S.D. KiM ; S.W. Hong ; G.H. Oh ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 66~75
A fault diagnosis system for a variable speed rotating shaft probably demands a huge database, which makes it diffcult to be realized. This stuydy presents an effective method of fault diagnosis for variable speed rotating shafts. The proposed method is based upon a fuzzy reasoning and it includes a stepwize strategy to reduce the size of database in a diagnosis system. A computer program is developed to show the procedure of the diagnosis, and four cases of faults are applied to the program to illustarate the effectiveness of the proposed method. The propsed method is found to be useful in reducing the size of database from observation of the data files of the dianosis system. The case studies show that the proposed method can be useful for the diagnosis of variable speed rotating shafts.
Analysis of a Process Sequence in Precision Press Forming of Aperture and Construction of Design System
S.K. Byun ; B.W. Huh ; B.S. Kang ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 76~84
A process sequence in precision press forming of electrnic components is investigated by the finite element method. Aperture, a key component of electronic gun, is formed through a sequence of about 15 operation, among which the beading & bending, the first piercing, the first coining, and the second coining operations are expected to be most critical in view of industrial experts opinions. Thus, the analysis per- formed by a commercial code MARC focuses on the three operations, and comparisons are made between the results of the analysis and the measurements of experimental forming of the component.
Reducing the Non Grinding Time in Grinding Operations(1st Report) -Reducing the Air Grinding time using Sound Sensor-
Kim, S.H. ; J.H. Ahn ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 85~91
Air grinding time in grinding process has a great effect on its efficiency due to low feedrate. This paper presents a reduction methos of air grinding time in cylindrical plunge grinding operation. Tje reduction of air grinding time is accomplished by finding the distance between contact point and rising point of ultra- sonic signal of the grinding wheel to workpiece. It uses a variation of sound signal generated by the flow of coolant when the grinding wheel approaches to workpiece. The ultrasonic sensor with 23 kHz center fre- quency and 8 kHz bandwidth is used to find the nearest approaching point(NAP). Monitoring and control system of the grinding conditions is implemented with CNC controller to control feedrate override and ultrasonic sensor to find NAP. The experimental result shows that the ultrasonic signal is a good measure- ment to find NAP. But it needs the considerations for the effect of the relationship between flowrate of coolant and diameter of workpiece.
A study on control of electrohydraulic servosystem with using model reference adaptive contorl theory
K.H. Kim ; I.R. Yun ; J.K. Kim ; M.O. Yum ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 92~99
A model reference adaptive control(MRAC) theory is very useful for controlling a plant of which the parameters are unknown or vary during operation usint only input-output signal of plant. In this study, 2' nd order discreter time MRAC controller is designed for an electrohydraulic position control system which is represented with nonlinear mathematical model and the least square method is adopted for the para-meter adjustment law. This control algorthm is applied to the position control of electrohydraulic servosystem through computer simulation and the effect of the change of load, sampling time upon the performance following reference model and upon the performance of estimating plant parameters are examined.
Adaptive Control for Trajectory Tracking of a Manipulator with Pneumatic Artificial Muscle Actuators
H.W. Park ; N.C. Park ; Y.P. Park ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 100~107
A pneumatic artificial muscle type of actuator, which acts similar to human muscle, is developed recently. In this paper, an adaptive controller is presented for the trajectory tracking problem of a two-degree- of-freedom manipulator using two pairs of pneumatic artificial muscle actuators. Due to the nonlinearity and the uncertainty on the dynamics of the actuator, it is difficult to make the effective control schemes of this system. By the adaptive control law which inclueds a nonlinear "feedforward" term compensating paramet- ric uncertainties in addition to P.I.D. scheme, both golbal stability of the system and convergence of the tracking error are guaranted. The effectiveness of the proposed control method for the manipulator using this actuator is illustrated through experiments.periments.
Robust Digital Nonlinear Friction Compensation-Application
M.S. Kang ; W.G. Song ; S.K. Lee ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 108~117
To prove the stability and the effectiveness of the robust non-linear friction control suggested and proved analytically in the previous paper
A Study on the Micro Stepping Drive to Reduce Vibration of Step Motor
G.B. Shin ; J.W. Lee ; J.H. Oh ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 118~127
In this study, We use microstep control to reduce vibration of step motor. Microstep control of step motor is usually thought of as an extension of conventional step motor control technology. The essence of micro stepping is that we divide the full step of a step motor into a number of substep called microstep and cause the stepmotor to move through a substep per input pulse. In ideal case, by controlling the individual phase currents of a two-phase step motor sinusoidally we can get uniform torque and step angle. But due to the nonlinear characteristics of the step motor, we need to compensate current waveform to improve the over-all smoothness of the conventional micro stepping system. We implement digital Pulse Width Modul- ation (PWM) driver to drive step motor and microphone was used for detecting vibration. Driver enables speed change automatically by increasing or decreasing micro stepping ratio which we call Automatic Switching on the Fly. To compensate the torque harmonics, neural network is applied to the system and we found compensated optimal input current waveform. Finally we can get smooth motion of step motor in a wide range of motor speed.
A Statistical Study on the Fatigue Behaviors of Nitro-Carburized SCM415
S.H. Song ; S.H. Lee ; S.H. Lim ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 128~133
Due to their high strength and good wear resistance, nitro-carburizing materials have been used for many machine components. However, the nitro-carburizing materials are found to have one disadvantage ; that is, their strength and fatigue life show larger scatter than those of non-heated metals. In this paper, therfore, the statistical chracteristics of non-heated and nitro-carburized specimens for SCM415 are investi- gated under two different of stress levels 1.15 .sigma. /sub .omega. / .leq. / .sigma. / sub .alpha. / .leq. / 1.25 .sigma. /sub .omega. /. Seven specimens at each stress level are tested by using rotating bending fatigue tester. The relation between a crack length and fatigue cycles can be arranged for Weibull distribution, and S-N curve using 95% reliability function is obtalined for nitro-carburized specimen.
Full Pose Measurement of a Robot by the Wire Parallel Mechanism
J.W. Jeong ; S.H. Kim ; Y.K. Kwak ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 134~142
In this study, we proposed the wire parallel mechanism that can be used to measure a full pose of a robot. It is composed of six parallel links using wire. The position and orientation of the end effectorf of a robot are calculated using the length of wires which is measured by the encoder. The complex non- linear equations of the forward kinematics are solved by using a numerical method, and the unique solution is obtained from the geometric configuration of the device. The length error of the wire which occurs in static condition is compensated by the relational equation that considered longitudinal extension and defoection of the wire. Through this work, we known that the proposed device has a good accuracy( .+-. 0.01mm) in a large measuring region, so it can be used effectively in a callibration of a robot which required a low cost.
Image Analysis of Wear Debris on Operating Condition of the Lubricated Moving Surface
Y.B. Seo ; H.S. Park ; K.Y. Lee ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 143~149
This paper was undertaken to do image analysis of wear debris on operating condition of the lubricated moving surfaces. This lubricating wear test was performed under different experimental conditions using the wear test device was made in our laboratory and wear testing specimen of the pin on dist type was rubbed in paraffine series base oil, by materials, varying applied load, sliding distance. The four shape parameters (50% volumetric diameter, aspect, roundness and reflectivity) to describe wear debris have been developed and are outlined in the paper. A system using such techniques promises to obviate the need for subjective, human interpretation of particle morphology for machine condition monitoring, this to overcome many of the difficulties with current methods and facilitating wider use of wear particle analysis in machine condition monitouing.
Crack growth behavior in the lntegrally stiffened plates(1) -Numerical evaluation of SIF
H.W. Rhee ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 150~156
Three dimensional finite element analysis was conducted to estimate the effect of shape parameters (plate width and thickness) on the stress intensity factor for crack in the integrally stiffened plate. Analysis was done for width ratios of 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, and thickness ratios of 2, 3, 4, 6. Based on these results, an empirical equation of geometry factor is formulated as a function of crack length and thickness ratio.
Study on the floating coupling for high precision feeding with ballscrew
C.H. Park ; I.C. KiM ; H.S. Lee ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 5, 1997, Pages 157~163
In the case of direct connecting the nut of ballscrew to guide table, machining error and misalignment of ballscrew largely affect to the motional accuracy of guideway. For decreasing these influences, two type of floating couplings: leaf spring type and hybrid type which releases the table from nut of ballscrew except feed and rotational direction is proposed in this study. In order to verify practical availability of the proposed floating couplings, motional accuracy, dynamic characteristics and micro step response of hydrostatic guideway, mounted with each type of couplings are tested. The conventional fixed type coupling is also tested as the reference in characteristics. From the results of experiments, it is proved that the hybrid type coupling is superior to other couplings and is available to high precision feeding system with ballscrew.