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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
Editor in Chief :
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
A study on the stroke sensitive shock absorber
Park, J.W. ; D.W. Joo ; Kim, Y.H. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 11~16
In the stroke sensitive shock absorber, the oil path is formed along the internal cylinder surface to make the oil flow during the piston's upper-lower reciprocation movement. In constrast with the conventional shock absorbesr which show one dynamic characteristic curve, stroke sensitive shock absorber shows two kinds of dynamic characteristics according to the stroke. In this study, in order to obtain more precise information about design and damping performance analysis, the analysis on the damping force generation process and dynamic behaviour characteristics of stroke sensitive shock absorber are performed by considering the valve characteristics.
A study on the formability estimation of deep drawing process by using taguchi method
Lee, B.C. ; Moon, J.H. ; Yang, D.Y. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 17~24
Despite the increasing demands for improved product design, a limited number of works have been reported in the field of sheet metal forming. In the present study, introducing the Taguchi method, an otpimal and robust combination of parameters in found and a data base management system is utilized for knowledge acquisition. Analysis data, estimation rules of formability and graphical representation of the analysis have been employed for the dewigner's understanding and evaluation. The developed system is applied to a deep drawing process. Through the present study, it is shown that the developed systerm is useful for the design and the formability estimation of sheet metal forming processes.
A study on the non-standard PID control for electro-hydraulic servo system
Lee, Y.J. ; C.S. Song ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 25~33
This study deals with controlling the velocity of Electr-Hydraulic servo system through the non-stan-dard PIC control. This was done as follows. First, we modeled nonlinearised model and linearised model, second designed analytic program for electro-hydraulic servo system velocity control Lastly, to im- prove dynamic characteristics of system we designed non-standard PID contoller and verifed throughth experi- ment and MATLAB program, commercial used software.
PID Control of a flexible robot rotating in vertical plane
J.W. Kang ; C.Y. Oh ; Kim, K.H. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 34~41
This paper presents a technique to control a very flexible robot moving in a vertical plane. The flexible robot is modeled as an Euler-Bernoulli beam. Elastic deformation is approximated using the assmed modes method. A comparison function which satisfies all geometric and natural boundary conditions of a cantilever beam with an end mass is used as an assumed mode shape. Lagrange's equation is utilized for the development of a discretized model. A control algorithm is developed using a simple PID cnotrol tech- nique. The proportional, integral and deivative control gains are determined based on the dominant pole placement method and tuned to show no overshoot and no steady state error, and short settling time. The effectiveness of the developed control scheme is showed in the hub angular diaplacement control experiment. Three different end masses are uned in the experiment. The experimental results show that developed control algorithm is very effective showing little overshoot, no steady state error, and less than 2.5 second settl- ing time in case of having an end mass which is equivalent to 45% of the manipulator mass. Also the experimental results show that the residual vibration fo the end point is effectively controlled.
A study on precision drive mechanism for monochromator grating
Kim, D.S. ; Park, K.B. ; Kwak, Y.K. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 42~49
The extent of absorption and transmitance of the light that passes through some material is changed as the wavelength of the light varies, and which makdes it possible to estimate characteristics of the material. Spectrometer is a measurement system that can analyze the characteristics of material by using this principle. Its application field is so wide that it can be applied to all the arease that are concerned with analyzing materials : biological, environmental, medical and chemical area etc. This study is focused on developing precision sine drive mechanism for grating monochromator which is the most important part of the spectrometers. It is designed to be simple in struicture. It is achieved to derive basic principles to manipu- late precision sine drive mechanism : it should be aligned with a condition that .beta. , the angle between grat- ing normal and grating rod should be the same as .gamma. , the one between moving nut's normal and sliding guide. And also, it's found that the mis-alignments of the grating and mirrors are not the main factor in guaranteeing the linearity of sine drive mechanism. Performance evaluation is achieved by a standard sample by comparing experimental results with standard values. It results in wavelength accuracy of .+-. 0.5nm and resolution of 1nm. Conclusively, it can be verified that the sine drive mechanism developed in this study is not only simple in structure, but also stable and excellent in performanes.
Chatter control and tool condition monitoring of turning processes using sound pressure
Lee, S.I. ; S.C. Chung ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 50~57
In order to make unmanned machining systems with satisfactory performances, it is necessary to incorporate appropriate condition monitoring systems in the machining workstations to provide the required intelligence of the expert. This paper deals with condition monitoring for chatter, tool wear and breakage during turning operation. To develop economic sensing and identiffication methods for turning processes, sound pressure measurement and digital signal processing technique were proposed. We suppressed chatter by stability control methodology, which was studied through manipulation of spindle speeds regarding to chatter frequencies. It was shown that tool wear and fracture were identified and to be estimated by using the wear indices. The validity of the proposed system was confirmed through the large number of cutting tests.
Residual stress formation in injection-molded samples under constrained quenching
K.H. Yoon ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 58~68
The residual stresses in injection-molded plastic parts can be divided into two, i.e., the flow-induced residual stress produced in flowing stage and the thermally-induced residual stress produced in cooling stage. Especially, the main source for the defect in the final parts, such as warpage, is known to be the thermally-induced stresses. For the freely quenched samples the structures of residual stresses and bire-fringence have been investigated by many researchers extensively. However, the boundary condition for free quenching was found to be improper to study actual injection molding process. In the present study a datailed structure of the residual stresses and birefringence produced under constrained quenching has been investigated experimentally. In constrained quenched samples a similar pattern but much less stress values than that for the freely quenched samples has been found in the case of the thickness of 1.0 mm. Howvere, in the case of the thickness of 4.0mm, totally different stress profile has been found experimentally. Suprisingly uniform birefringence throughout whole thickness has been found for all the cases of constrained quenching. Finally, to explain the mechanism to produce the final residual stresses and bire-fringence some preliminary numerical results including free volume theory have been introduced briefly.
Fatigue behavior of Cr-Mo-V steel at high temperature for turbines -Propagation characteristics of high cycle fatigue crack-
S.H. Song ; M.S. Kang ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 69~76
The rotating bending fatigue tests were performed using the specimens taken from Cr-Mo-V steel, widely sued in thermal power plant turbines, at various temperatures such as room temperature, 300 .deg. C, 425 .deg. C and 550 .deg. C. The characteristics of fatigue crack propagation were examined and analyzed by using fracture mechanics parameter. The plastic replica method was also applied in order to measure the crack length on the basis of serial observation of fatigue crack propagation behavior on the defected specimen surface. The fatigue crack propagation behavior of Cr-Mo-V steel was investigated within the frame work of elastic-plastic fracture mechanics. The propagation law of fatigue crack is obtained uniquely by using the term .sigma.
sub a/where .sigma.
is the service stress, a is the crack length and n is a constant. The values of constant n are nearly equal to 2.48, 2.60 and 8.61 at room temperature, 300 .deg. C and 425 .deg. C.
An improved NC-code generation method for circular interpolation
M.Y. Yang ; T.Y. Shon ; H.D. Cho ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 77~83
This work is concerned with the algorithm of generating a new circular are interpolation. This research presents a new biarc curve fitting that is a circular interpolation method based on a triarc curve fitting. The triarc method, where a segment span is composed of three circular arcs, using maximum error estimation has the advantage of generating arc splines easily to a given tolerance. The new biarc method is called when the adjacent radii are the same in the same in the triarc method. In generating the machining data for various cam curves in CNC machining with the biarc method and the new biarc method, the latter accomp- lished faster NC-code generation, shorter NC-code block formation and machined the same cam profile more efficiently.
A study on the measurement of rotary table error with 5-axis CNC machine
S.H. Suh ; S.Y. Jung ; Lee, E.S. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 84~92
The purpose of this study is to develop a geometric error model and path compensation algorithm for rotating axes of the 5-axis machine tools, by a method to calibrate a rotary table using one master ball and three LVDTs. It was developed a new methodology to measure 3 translation errors of the rotary table and with a compensation procedure for setup errors of the master ball. The method is experimentally verified using a ball-table and on-machine inspection method. The results showed that the geometric error models with the path compensation strategy can be practically used as a means for improving the accuracy of the machine tools with rotary table.
Chaotic analysis of tool wear using multi-sensor signal in end-milling process
Kim, J.S. ; Kang, M.C. ; Ku, S.J. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 93~101
Ever since the nonlinearity of machine tool dynamics was established, researchers attempted to make use of this fact to devise better monitoring, diagnostics and control system, which were hitherto based on linear models. Theory of chaos which explains many nonlinear phenomena comes handy for furthering the analysis using nonlinear model. In this study, measuring system will be constructed using multi-sensor (Tool Dynamometer, Acoustic Emission) in end milling process. Then, it will be verified that cutting force is low-dimensional chaos by calculating Lyapunov exponents. Fractal dimension, embedding dimension. And it will be investigated that the relation between characteristic parameter calculated from sensor signal and tool wear.
control of a seeker scan loop using normalized coprime factorization
Lee, H.P. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 102~109
A two-degree-of freedom (TDF)
controller for a seeker scan loop is presented for the purpose of improving scanning performances. The perturbed plant model is characterized via the normalized coprime factorization. The TDF
controller is designed based on the loop shaping design procedure and model matching approach, and its performances are evaluated and compared with those of a previous work. It is demonstrated that the proposed TDF
controller is more effective to the control of the seeker scan loop than the previous controller.oller.
A study on a capacitive displacement sensor for the ultraprecision measurement
H.J. Ahn ; I.B. Chang ; D.C. Han ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 110~117
This paper discusses numerically and experimenally several design parameters for the plate- type capacitive displacement sensor. The influenences of shape of this sensor on the sensitivity are numerically analyzed with the charge density method. Using many test sensor plates of different shape for verifing the validity of this method can not guarantee the repetibility of experiments. Therefore we made specially the test sensor plate so that experiments of effects of shape of this sensor on sensitivity can be done with only that plate. Results from these experiments agree well with those from numerical analysis.
Calibration of Optical Dimensional Measurement System Using Optical Microscope
H.G. Part ; M.C. Park ; S.W. Kim ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 118~125
Non-contacting optical microscopes are increasingly used in recent industrial applications of probes for coordinate measuring machines. They have been found more efficient than conventional touch trigger porbes with ball tips especially in inspecting small-sized objects. There are two major factors affecting measuring accuracy: (1) geometric relations between coordinate systems, (2) magnification ratios of a microscope. In order to determine the magnification ratios exactly, optical imaging of edge was theroretically analyzed and practically adopted to image processing for edge detection. In addition, this paper proposes a geometric calibration method to obtain exact coordinates of measured points from the relations between the machine coordinate system and the image. In the method, the error according to the squareness between the machine axises was also removed. The method was practically adopted to a real coordinate measuring machine. An ultraprecision measurement of 0.2 um uncertainty can be practically achieved.
The Development of Visual Inspection for Length Measurement of Injection Product Using Vision System
J.Y. Kim ; B.S. Oh ; S. You ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 126~134
In this study, We made visual inspection system using Vision Board. It is consist of an illuminator (a fluorescent lamp), image input device (CCD (Charge-Coupled Device) camera), image processing system(Vision Board(FARAMVB-02)), image output device (video monitor, printer), and a measuring instrument(TELMN1000). Length measurement by visual inspection system make use of 100mm guage block(instead of calculating distance between a camera and a object). It measured horizontal and vertical length factor from 400mm to 650mm by increasing 50mm. In this place, measured horizontal and vertical length factor made use of length measure- ment of a injection. A measuring instrument used to ompare a measured length of a injection visual inspection system with it. In conclusion, length measurement of a injection compared a measuring instrument with visual inspecion system using length factor of 100mm gauge block. We find that maximum error of length is 0.55mm when it compar with the measuring value of two devices(FARAMVB-02, TELMN1000). Program of visual inspection system is made up Borland C++3.1.
Fault Diagnosis Method of Complex System by Hierarchical Structure Approach
Y.H. Bae ; S.H. Lee ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 135~146
This paper describes fault diagnosis method in complex system with hierachical structure similar to human body structure. Complex system is divided into unit, item and component. For diagnosing this hierarchical complex system, it is necessary to implement special neural network. Fault diagnosis system can forecast faults in a system and decide from current machine state signal information. Comparing with other diagnosis system for single fault, the developed system deals with multiple fault diagnosis comprising Hierarchical Neural Network(HNN). HNN consists of four level neural network, first level for item fault symptom classification, second level for item fault diagnosis, third level for component symptom classification, forth level for component fault diagnosis. UNIX IPC(Inter Process Communication) is used for implementing HNN wiht multitasking and message transfer between processes in SUN workstation with X-Windows(Motif). We tested HNN at four units, seven items per unit, seven components per item in a complex system. Each one neural newtork operate as a separate process in HNN. The message queue take charge of information exdhange and cooperation between each neural network.
Development of Diagnostic Expert System for Machining Process Ffailure Detection
S.M. Yoo ; Y.J. Kim ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 147~153
Fault diagnosis technique in machining system which is one of engineering techniques absolutely necessary to automation of manufacturing system has been proposed. As a whole, diagnosis process is explained by two steps: sensor data acquisition and reasoning current state of system with the given sensor data. Flexible disk grinding process implemented in milling machine was employed in order to obtain empirical manufacturing process information. Resistance force data during machining were acquired using tool dynamometer known as sensor which is comparably accurate and reliable in operation. Tool status during the process was analyzed using influnece diagram assigning probability from the statistical analysis procedure.
Real time compensation for quasistatic errors of a horizantal machining center
S.H. Yang ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 154~162
A real time error compensation system was developed to improve the quasistatic volumetric accuracy of a machining center by using sensing, metrology, modeling, and computer control techniques. Including thermal errors, 32 error components are formulated in the time-space domain. Fifteen thermal sensors are used to characterize the temperature field of the machine. A compensation controller based on the IBM/PC has been linked with a CNC controller to compensate for machine errors in real time. The maximum linear displacement error in 4 body diagonals were reduced from 140
with this compensation system, and the spindle thermal drift in space was reduced from 147.3
Tool fracture detection in end milling using cutting force and acoustic emission propagated through cutting fluid
M.J. Maeng ; S.S. Cho ; J.K. Chung ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 163~170
End milling experiments are conducted to investigate characteristics of acoustic emission (AE) and cutting force singals due to tool fracture. The AE signals are obtained with a sensor attached to cutting fluid discharge nozzle. Tool states are identified with scanning electron microscopy and optical microscopy. It is demonstrated that the AE signals provide reliable informations about the cutting processes and tool states. Morever, tool fracture can be detected successfully using both the AE count rate and the standard deviation of principal cutting force.
A nesting system for blanking or piercing of irregular-shaped sheet metal products
J.C. Choi ; B.M. Kim ; H.K. Kim ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 11, 1997, Pages 171~179
This paper describes a nesting system of a computer-aided design of blanking and piercing for irregularly shaped sheet metal products. An approach to the system is based on knowledge-based rules. A nesting system is designed by considering several factors, such as utilization ratio which minimises the scrab for single or pairwise operation, bridge width, grain orientation and design requirements which maximise the strength of the part when subsequent bending is involve. Therefore this system which was implemented blank layout and strip layout module can carry out a nesting with a best utilization and a process planning for irregular shaped sheet metal products in single or pairwise operation and generate the blank layout and strip layout in graphic forms. Knowledges for a nesting and a process planning are extracted from plasticity theories, relevant references and empirical know-hows of experts in blanking industries. This provides its efficiency and effectiveness for nesting irregularly shaped sheet metal products.