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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 12, Issue 12 - Dec 1995
Volume 12, Issue 11 - Nov 1995
Volume 12, Issue 10 - Oct 1995
Volume 12, Issue 9 - Sep 1995
Volume 12, Issue 8 - Aug 1995
Volume 12, Issue 7 - Jul 1995
Volume 12, Issue 6 - Jun 1995
Volume 12, Issue 5 - May 1995
Volume 12, Issue 4 - Apr 1995
Volume 12, Issue 3 - Mar 1995
Volume 12, Issue 2 - Feb 1995
Volume 12, Issue 1 - Jan 1995
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Measurement of Fracture Toughness of WC-Co Composites by Micro-Vickers Indentation Cracks
Lee, O.S. ; Son, I.S. ; Park, W.K. ; Hwang, S.K. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 5~13
Various techniques to measure fracture toughness which is an important parameter to predict fracture behavious of structural materials have been reported. Among these mathods, this paper describes the micro-Vickers indentation crack method to estimate the fracture toughness of some WC-Co composites. Two indentation crack patterns (such as radial-median cracks (orhalf-penny cracks) and Palmqvist cracks generated during indentation) are referred precisely. The fracture toughness of WC-4.7wt%Co, WC-6wr%Co and WE-9wr%Co composites were estimated by using some equations given by Shetty et al., Nihara et al. in this study. We show the reliability of indentation method by comparing the results with those from literatures. The appropriate equation to estimate the fracture toughness in the case of WC-Co composite is given. In addition, some technical informations in terms of the crack length by indentation in estimating the existence of the surface residual stress that prevents to obtain an accurate fracture toughness are presented.
A study on vibration characteristics of passenger car tire under the static load
Moon, Il-Dong ; Lee, Tae-Keun ; Hong, Dong-Pyo ; Kim, Byoung-Sam ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 14~22
We treat the vibrations of circular beam and make use of the method employed by J.T.Tielking, which is based on the principle of Hamilton. The Hamilton's principle requires the determinations of the potential and the kinetic energy of the model as well as done by internal pressure forces. Thje potential energy is composed of a part due to elastic deformations of the beam and a part due to radial and tangential displacements of the tread band with respect to the wheel rim. The equations of motion for such a model are derived by reference to conventional energy method. The accuracy of the expressions is demonstrated by comparison of calculated and experimental natural frequencies for circular beam. The circular beam experiences a harmonic, radial excitat- ion acting at a fixed point on the beam. Modal parameters varying the inflation pressure and load are determined experimentally by using the transfer function method.
Tool Breakage Detection using Pattern Characteristics of Feed Motor Current in Milling Operations
Kim, S.H. ; J.H. Ahn ; Park, H.Y. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 23~34
This paper is concerned with effective and reliable tool breakage detection method using pattern characteristics of feed motor current in milling operations. Correlation coefficient is derived from the feature vector of signal for two consecutive which are extracted feed motor current over three spindle revolutions. The changing pattern of correlation coefficient is continuously compared to detect tool breakage and monitor cutting conditions. This proposed monitoring scheme is not affected by different tools, friction of motion, and varying cutting conditions and material shapes. Experimental results are presented to support the proposed monitoring scheme.
Developement of Measuring Units of Space Motion Accuracy in Machining Center
Kim, Y.S. ; S. Namgung ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 37~47
In recent years, it has been variously developed for testing the accuracy of circular motion of NC machine tools, for example Telescoping Ball Bar Method by Bryan, Circular test Method by Knapp and
Method by Tsutsumi etc., but these methods are all 2-dimentional measuring methods on plane. These simple methods of circular motion accuracy test of NC machine tools have been studied by many reserchers as above, but it is not yet settled in the code of measuring methods of motion errors of NC machine tools, because of errors of measuring units and sensors, and also especially the difficulties of centering of measuring units and the spindle of machining center. In this paper, in use of 2 rotary encoders and 1 magnetic type linear scale with resolution of 0.5 .mu. m, it has become possible for measuring of 3 dimentional space motion accuracy.
A Development of Micro-Positioning Grinding Table using Piezoelectric Voltage Feedback
S.R. Nam ; Kim, J.D. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 48~58
A micro positioning system using piezoelectric actuators have very wide application region such as ultra-precision machine tool, optical device, measurement systen. In order ro keep a high precision displacement resolution, they use a position sensor and feedback the error. From the practical point of view, a high-resolution displacement sensor system are very expensive and difficult to guarantee such sensitive sensors work properly in the hard opera- tion environment of industry. In this study, a micro-positioning grinding table which does not require position sensor but uses piezoelectric voltage feedback, has been developed. It is driven by hystersis-considering reference input voltage which calculated from computer and then uses actuator/sensor characteristics of piezoelectric materials. From the result of experiments we proved a fast and stable response of micro-positioning system and suggested efficient technique to control the piezoelectric actuator. And through grinding experiments, it is revealed that a characteristics of ground surfaces transient to plastic deformation as extremely small depth of grinding.
Effects of the Power Transmission Units on the Rotational Accuracy of A Hydrostatic Spindle
Park, C.H. ; Ryu, G.W. ; Jung, Y.G. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 59~68
In this study, the effects of the power transmission units on the rotational accuracy are investigated experimentally in a hydrostatic spindle. The effects of warm up time, unbalancing and the position of measuring sensor are pre-examined for the determination of measuring conditions. The misalignment of the power transmission units and the vibration excited by the fluctuation of belt are considered as the dominant parameters of error motion. The variation and scatter of run out at the range of 0 to 3,000rpm in rotational speed are appropriated for the camparison of availabilities of the transmission units to precision spin- dles.
A study on the Analysis of Dynamic Characteristic for Nonlinear Rotor-Housing Systems
Kim, G.G. ; Lim, J.H. ; Chung, I.S. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 69~78
Nonlinear analysis methods are developed which will enable the reliable prediction of the dynamic behavior of the space shuttle main engine(SSME) turbopumps in the presence of bearing clearances and other local nonlinearities. A computationally efficient convolution method, based on discretized Duhamel and transition matrix integral formulations, is developed for the transient analysis. In the formulation, the coupling forces due to the onlinearities are treated as external forces acting on the coupled subsystems. Iteration is utilized to determine their magnitudes at each time increament. The method is applied to a nonlinear generic model of the high pressure oxygen turthods, the convolution approach proved to be more accurate and highly more efficient. For determining the nonlinear, steady-state periodic responses, an incremental harmonic balance(IHB) method was also developed. The method was successfully used to determine dominantly harmonic and subharmonic(subsynchronous) responses of the HPOTP generic model with bearing clearances. A reduction method similar to the impedance formulation utilized with linear systems is used to reduce the housing-totor models to their coordinates at the bearing clearances.
A Study on the Frequency response charcteristics of Hydraulic Equipment using High speed on-off valve
J.Y. Huh ; G. Wennmacher ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 79~86
Frequency response method is used to design hydraulic servo systems and improve its performance. In this study a method is proposed to get simply the frequency response of the electro-hydraulic servo system which use PWM controlled high-speed on-off valves. Firstly, the describing function of the PWM element is derived and tested. It is found that the character- istic of PWM element could be approximated to a saturation characteristic in the range of allowable frequency. And the dynamic characteristic of the valve-cylinder system could be negligible. The working characteristic of high-speed on-off valve is considered as time delay. So simulation is performed in the basis of the reconstructed block diagram. And this method is verified by experiments.
A Development of Combined-Type Tool Dynamometer for Ultraprecision Lathe with Piezo-Film Accelerometer
Kim, J.D. ; Kim, D.S. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 87~96
The cutting force is the most important variable to understand the mechanics of ultra-precision machining. Most dynamometers, however, monitor the static cutting force only. But it is necessary to measure the dynamic cutting force to clarify the machinability of the material, the formation of the chip, chatter and the wear of the tool. In this research, measurement of the dynamic cutting force in order to clarify the machin-ability of the material, the formation of the chip, chatter and the wear of the tool has been conducted. A combined-type dynamometer which could measure the static cutting force and the dynamic cutting force by use of strain gauges and a piezo-film accelerometer has been developed. An analysis of the dynamometer also has been carried out.
Path compensation toward direct shape control: dealing with tool deflection problem in 2D contour machining
J.H. Cho ; S.H. Suh ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 97~111
In this paper, we investigate path compensation scheme for the machining errors due to tool deflection in 2D contour machining. The significance of the deflection error is first shown by experiments, and a direct compensation scheme is sought. In the presented scheme, the tool path is evaluated and correcte based on the instantaneous deflection force model, until the desired contour can be obtained under the presence of tool deflection in actual machining. In the sense that the developed method estimates and compensates the machining errors via modifying the tool path, it is distinguished from the previous approach based on geometric simulation and cutting simulation. Further, it can be viewed as a direct and active method toward direct shape control in CNC machining. Simulation results are included to show the validity and adequacy of the path-modification scheme under various cutting conditions.
A Feature-based Approach to Compound Surface Design
J.H. Jeong ; Kim, K.S. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 112~122
While many surfaces such as automobile outer panels, ship hulls and airfoils are characterized by their smooth, free-form shapes, a far larger class of functional surfaces are characterized by highly irregular, multi-featured shapes consisting of pockets, channels, ribs, etc. In constaract to the design of aesthetic, free-form surfaces, functional surface design can perhaps best be viewed as a process of assembling a collection of known component surfaces to form a single compound surface. In this paper, we presents a feature-based functional surface modeling method. A single feature involves a secondary surface, which we must join to a primary surface with a smooth transition between two boundary courves. Through recursive blending of a secondary surface with the primary surface, the mullti-featured surface is represented. After constructing a compound surface, we generate the Z-map for NC machining of the surface. Offsetting the Z-map using the inverse offsetting technique, we get CL tool paths with out gouging.
Verification System for Cutting Condition of Ball-End Milling Process
Kim, C.B. ; M.Y. Yang ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 123~134
In this paper, the fast force algorithm has been studied so that it is used to calculate cutting forces and to develope the NC verification system. The NC verification using the fast force algorithm can verify excessive cutting force which is the cause of deflection and breakage of tool, and adjust the feed rate and spindle speed.
Rule-Based Path Finding Algorithm for Part Assembly and Its Extension to Mobile Robot Path Planning
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 135~144
A Study on Navigation Strategy of a Mobile Robot with Fuzzy Control
J.H. Jung ; D.K. Hong ; J.M. Kim ; S.G. Lee ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 145~153
This paper proposes a fuzzy algorithm for determining navigation path of an autonomous mobile robot in uncertain environment. The proposed fuzzy algorithm includes three type (MIN-TIME, ECONOMY, SAFETY) motion modes for the robot to get the ability to meet the ambiguous situation which the robot encounters. Ech ode is applied to both static and dynamic environmental situation. This paper concludes by showing the efficiency of the proposed method through some computer simulation results.
Analysis of the stress disribution around flaws and the interaction effects between fatigue cracks by finite element method
S.H. Song ; Kim, J.B. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 154~161
In order to analysis of the stress distribution around flaws and the interaction effects between fatigue cracks, stress around micro hole was analyzed by Finite Element Method(F.E.M.) and micro hole specimens were tested using rotary bending fatigue machine and twisting fatigue machine to identify stress effects for fatigue cracks initiating from micro holes and interaction effects between micro holes. The results are as follows : Interaction effects of .sigma.
for the micro hole side is larger than the large micro hole side when the interval between micro holes is near. Stress concentration factor increase as the diameter of micro hole becomes smaller. But, stress field of micro hole is smaller than that of large micro hole at h .leq. r (h:depth of micro hole, r:radius of micro hole) and that of large hole is larger than that of small micro hole at h >r expect the small range from micro hole.e.
A Study of Mesh Automatic Generating Method for Cracked Body
Park, S.O. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 2, 1995, Pages 162~172
In this paper new mesh generation method is proposed for crack propagation analysis based on the finite element method. The main tool of the method is the Delaunay Triangulation, Transfinete element mapping, and it allows the setting of the arbitrary crack-growth increment and the arbitrary crack direction. It has the form of a subroutine, and it is easily introduced as a subroutine for any mesh generation method which is based on the blocking method.