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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 11, Issue 6 - Dec 1994
Volume 11, Issue 5 - Oct 1994
Volume 11, Issue 4 - Aug 1994
Volume 11, Issue 3 - Jun 1994
Volume 11, Issue 2 - Apr 1994
Volume 11, Issue 1 - Feb 1994
Selecting the target year
기계가공프로세스의 감시를 위한 지적센싱시스템
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 8~14
정밀 고속 가공을 위한 절삭공구의 개발
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 15~29
The utilization of a positioner for robot welding process planning
Kim, D.W. ; Park, J.S. ; S.M. Yang ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 30~41
Presented in this paper is the utilization of a positioner in a robot arc welding system to increase the quality and the productivity of the system. It is well known that downhand or flat position welding is essential for fine quality of arc welding. A positioner having more than two degress of fredom can perform the downhand welding by making normal vectors of weldline be parallel with the direction of gravity. First, inverse kinematics of the positoner to make the downhand welding system is derived and graphically simulated. Secondly, interrelation- ship between each pair of torch orientation, weld quality, and weld productivity is mathematically modeled and examined using a stable area and a stability function. Finally, process planning procedures for multi-weldine/multi-layer weldings are proposed to demonstrate the usefulness of aforementioned methods.
The end-point control of flexible manipulator using the accelerometer
Lee, J.W. ; H.H. Joo ; C.B. Shin ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 42~51
Instead of the strain signal which is generally used in the beam vibration control, the acceleration signal is used as the feedback signal for the end-point control of a flexible manipulator. The reason is that the strain gage is impossible to be used for feedback signal if the strain gage is deformed permantly under overload. On the contrary, the accelerometer is a simple and reliable sensor in the actual control enviorment. However, the ene-point acceleration feedback system has a limited control performance because of its nonminimum phase property. Moreover more impulse signal penetrate into the controller through the accelerometer signal line. In this experiment the acceleration feedback could get the similar control performance with the strain gage feedback uaint Butter-Worth filter which can not only remove the external noise but also move the system pole to stable regin.
A study numerical analysis on the vibration characteristics of bearingless helicopter rotating blade
Lee, H.S. ; Lee, K.H. ; I.S. Chung ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 52~63
The bearingless rotorcraft offers reduced waight, less complexity and superior flying qualities. The bearingless rotors are presently being developed and it is most likely that the next generation rotorcraft would be equipped with these rotors. Almost all practical designs of bearingless rotors include multiple load paths. The flexure of a bearingless blade consists of multiple beams (fflexbeads and troque tube) leading to redundancy. Numerical results are presented for several analytical models of the bearingless blade.
A study on the bending vibration characteristics of twisted rotating cantilevered blade
C.S. Hyun ; Lee, K.H. ; I.S. Chung ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 64~74
Analysis and computation procedures are developed to study the natural vibration characteristics of rotating blade. Myklestad's method is used for the analytical study. Experiments are performed to validate the results of numerical analysis. The bending natural vibration characteristics of a blade with rectangular, airfoil and twisted cross-section can be determined. Computed resultsd are compared with the experimental results obtained by FFT analyzer. Then, computed results have a good agreement with the experimental results.
A study on the torsional vibration of vehicle driveline
Y.J. Youn ; S.H. Tae ; T.J. Joung ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 75~81
The engine flywheel-transmission-body of vehicle train of an automobile is modeled by a forced torsional vibration system and the clutch is modeled by the torsional damper with the linear stiffness and hysteresis. For a single frequency excitation and primary resonance, the steady-state solutions are obtained for three degree-of-freedom model. Bsed on these solutions, the effect of the torsional stiffness and hysteresis provided between the sub plate and spline hub of the clutch disk on resonance generated at manual transmission and body of vehicle during engine driving of an automobile is investigated. It is shown that this analysis provides understanding of behavior of the transmission and body of vehicle.
Motion control of direct drive robots using robust deterministic control theory
C.G. Kang ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 82~95
This paper presents an application of the robust deterministic control proposed in the earlier paper to the motion control of direct drive robotic manipulators. Inertia variations due to kinematic changes, unknown and time-varying paylod. Coriolis and centrifugal accelerations, and friction and gravitational torques are considered as uncertainties in the formulation. "Parasitic" actuator and sensor dynamics of the robot system are considered in the controller design and analysis by means of a singular perturbation technique. Simulation and experimental studies have been conducted for a two degree of freedom, direct drive SCARA robot to evaluate the control performance.
A study on the computer-aided design of blocker for Rib/Web shaped axisymmetric parts
Park, J.C. ; Kim, B.M. ; H.K. Kin ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 96~104
This paper describes computer aided design of blocker for rib/web shaped axisymmetric parts by the press. In the process called closed die forging with flash, the design of blocker genometry is of critical importaance. It involves a three dimensional geometry design, but common practices in the design of blocker geometry are to consider as a certain cross section of the forgings. Accordingly, a three dinensional blocker geometry design problem can be considered as a two dimensional geometry design problem. A blocker geometry is estibilished by modifying the final product. The rules and databases for blocker design are extracted from plasticity theories, relevant references and empirical know-how of field experts in hot forging companies. The developed system provides powerful capabilities for blocker design of rib/web shaped axisymmetric parts.
Analysis of the residual strengths and failure mechanisms in laminated composites under impact loading
Park, K.C. ; Kim, M.S. ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 105~121
In this paper, we proposed the two-parameter model for predicting the residual strength in CFRP laminated composites subjected to high velocity impact and developed and formulated it based upon Cparino's by using the ratio of impact and the normalized residual strength. Critical indentation was obtained by the statical indentation tests. Impact tests were carried out through air-gun type impact equipment with the velocities varied 30-100m/sec. Projectiles were steel balls with 5 and 7mm in diameter. Test material was carbon/epoxy. The specimens were composed of [ .+-. 45 .deg. /0 .deg. /90 .deg. ]
2/ and [ .+-. 45 .deg. ]
4/stacking sequences and had 0.75
L/(mm) dimension. Results from the proposed model were in good agreement with the test data. And failure mechanism due to high velocity impact is given here to examine the initation and deveolpment of damage by fractography and ultrasonic image system. The effects of the 0 .deg. -direction ply position and the amount to damage area on the residual strength are considered here.
Optimal control of an elastic two-link manipulator in gravity
C.Y. Oh ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 122~130
This paper develops a control algorithm for end point position control of an elastic two-link manipulator. First, an algotithm is developed to solve for the state variables as a function of end point position. This is used to determine a set of traget state variables. A control algorithm is developed using a linear quadratic optimal control technique on an infinite time interval with the prescribed degree of stability method to control the movement of the end point from a specified initial end point position to a specified terminal end point position. For the system dynamic equations, second order nonlinear differential equations including the shortening effect are linearized with respect to the terminal position and are put into first order. The simulation shows that the developed control allgorithm results in effective end effector control with short response time and little overshoot. Also, the simulation shows that the results with one and two flexible modes for each arm have small differences in the early stage of the end point control but the results are almost identical later in the simulation.
Leaser range finder for real-time navigation of a free ranging mobile robot
Y.Y. Cha ; D.G. Gweon ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 131~139
In this study an active vision system using a laser range finder is proposed for the navigation of a mobile robot in unknown environment. The laser range finder consists of a slitted laser beam generator, a scanning mechanism, CCD camera, and a signal processing unit. A laser beam from laser source is slitted by a set of cylindfrical lenses and the slitted laser beam is emitted up and down and rotates on the surface of an obiect is engraved on the CCD array. A high speed image processing algorithm is proposed for the real-time navigation of the mobile robot. Through experiments it is proved that the accurate and real-time recognition of environment is able to be realized using the proposed laser range finder.
An analysis of micro surface-generation in ultrasonic vibration cutting of optical plastics
Park, I.H. ; Kim, J.D. ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 140~148
Mirror-surface machining is very important machining technology to manufacture optical parts, especially brittle materials. In case of optical plastics, it is produced through both grinding and polishing till now. New machining method which is more efficient and contributed to the protection of the environmental pollution is, therefore, studied. In this study, experimental results and an analysis of surface roughness in ultrasonic vibration cutting of optical plastics(CR-39) which is used for optical lens are presented. In results, a comparison of the micro-structure of machined surface produced by cutting with ultrasonic vibration and conventional turning is presented by analyzing S.E.M. photograph. Also, wavelength spectrum analysis is performed to investigate the surface-characteristics machined by ultrasonic vibration cutting.
A study on the grinding of engineering ceramics with high quality using conventional grinding machine
J.H. Kang ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 149~161
In this study, grindability of some representative engineering ceramics are experimentally investigated using resin bond diamind wheel with conventional surface grinding machine. And the optimum machining process step considering such various results as total machining cost, total machining time, and ground surface layer quality which is proper to domestic circumstances for manufacturing of the mechanical component is investigated also. Furthermore, each proper dressing process and condition suing WA stick type dresser for the most effective dressing of resin bond diamond wheels with various mesh number is established experimentally. Through the results of experiment, it is confirmed that there is scarecely any difference for improving ground surface roughness using diamond wheel with over mesh number 1000 in this experimental conditions. And it is confirmed also that 3-step type grinding process using diamond wheel with mesh number 120, 600, 1000 with proper machining conditions is the most useful case in the view of economic productivity for manufacturing of mechanical components. And moreover, the total table pass number needed for sperk-out process to be completed for removing unmachined quantity depend on their mechanical properties because that dynamic grinding stiffness is different from each other. The grinding force, grinding power and ground surface roughness are also measured and compared. Through the experiments carried out in this study, some useful results are obtained which can guide to grind engineering ceramics with conventional surface grinding machine.
Estimation of the weld pool size in GMAW processes using multiple surface temperatures measurements
Y.J. Won ; H.S. Cho ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 162~174
This paper describes a detailed procedure for establishing an index to estimate a weld pool size in gas metal arc welding processes using measurements of multiple surface temperatures. Up to now, estimation of a weld pool size based on the surface temperature field formed during welding has been performed using one point temperature. However, owing to the complexity and nonliearity inherent to the welding processes, it is nearly infeasible to specify the temperature field by one point temperature alone, and thereby difficult to consistently quantify the pool size. Therefore, in addition to one point temperature, the temperature differences along and perpendicular to the weld line are adopted to compensate for such a deficiency. To extract the pool size information from these temperature parameters the indices to estimate the respective pool size parameters(top bead width and depth of penetration plus half back bead width) are derived using a multiple regression method. The estimation performance of the indices are investigated through simulation studies and experiments. Advantages of using the index are investigated by comparing with the case of using one point temperature. Eventually, the effectiveness of using the index in practical situation is discussed, in detail.
간섭무늬 자동화해석: 전문가 시스템
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 175~183
Dynamic characteristics of spindle with a built-in motor
Park, D.B. ; J.J. Jo ; Kim, S.I. ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 184~190
The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. In this study, the dynamic characteristics of spindle with a built-in motor are quantitatively analyzed by intoducing the finite element model based on the Timoshenko theory and considering the mass and stiffness effects of the built-in motor's rotor. And an identification method of the elastic modulus of built-in motor's ortor is proposed by using the last square error method related to the experimental and theoretical natural frequencies. The experiment on the test model reveals the usefulness of the proposed identification method.
Investigation of metal transfer in GMAW using pinch instability theory with arc pressure
S.H. Rhee ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 191~196
Metal transfer in GMAW influnces on the weld bead formation and arc stability. If the drop frequency is high, the spray transfer occurs and welding sound is smooth. Arc pressure cannot be negligible comparing with the electromagnetic pressure in the development of instability. The dispersion equation was obtained using perturbation theory in terms of arc current density as well as metal current density. The drop diameters considering the arc pressure effect were found to be greater than those drop diameters that were obtained without the arc effect.
A study of force control of a miniature gripper
T.J. Chung ; D.P. Hong ; S.J. Chonan ; M. Koseki ;
Journal of the Korean Society for Precision Engineering, volume 11, issue 3, 1994, Pages 197~203
A theoretical and experimental implementation of the dynamic of the dynamic force control of a miniature gripping mechanism driven by piezoelectric bimorph cell is describec. To investigate in case of gripping a tiny object with fingers then holding it with the minute commanded force even if the object is in motion. One finger of the miniature gripper modeled by a flexible by a flexible cantilever with a force sensor is attached to its force end. A fare of piezoelectric bimorph cells are glued to both sides of the stepped beam with two uniform section. In the analysis, the PID control scheme is introduced to drived finger so that finger tip produces 0.03N. Theoretical and experimental results for several cases illustrate commanded force-actural force and response time relationshipe.