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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Manufacturing Technology Engineers
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Journal DOI :
The Korean Society of Manufacturing Technology Engineers
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Volume & Issues
Volume 7, Issue 6 - Dec 1998
Volume 7, Issue 5 - Oct 1998
Volume 7, Issue 4 - Aug 1998
Volume 7, Issue 3 - Jun 1998
Volume 7, Issue 2 - Apr 1998
Volume 7, Issue 1 - Feb 1998
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A new Approach to Moving Obstacle Avoidance Problem of a Mobile Robot
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 9~21
This paper a new solution approach to moving obstacle avoidance problem of a mobile robot. A new concept avoidability measure (AVM) is defined to describe the state of a pair of a robot and an obstacle regarding the collision between them. As an AVM, virtual distance function (VDF), is derived as a function of the distance from the obstacle to the robot and outward speed of the obstacle relative to the robot. By keeping the virtual distance above some positive limit value, the robot avoids the obstacle. In terms of the VDF ,an artificial potential field is constructed to repel the robot away from the obstacle and to attract the robot toward a goal location. At every sampling time, the artificial potential field is updated and the force driving the robot is derived from the gradient of the artificial potential field. The suggested algorithm drives the robot to avoid moving obstacles in real time. Since the algorithm considers the mobility of the obstacle as well as the distance, it is effective for moving obstacle avoidance. Some simulation studies show the effectiveness of the proposed approach.
A Study on the Evolution of Local Plasticity and the Bauschinger Effects in Short Fiber Reinforced Metal Matrix Composites
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 22~33
A continuum analysis of the evolution of plasticity and Bauschinger effect in a short fiber reinforced metal matrix composite, based on the FEM solution for a single fiber model has been performed to investigate the strengthening behavior. The evolution of matrix field quantities during one cycle of fully reversed loading have been examined in detail. The results indicate that the role of constrained matrix flow in generating different levels of matrix triaxiality during forward and reversed loading provides an important contribution to the developement of the Bauschinger effect in the metal matrix composite. Therefore, even when the plastic flow of the matrix material follows on isotropic hardening behavior, the Bauschinger effect is predicted for the composite material.
Die Sinking Electrical Discharge Machining of SiC/AI Metal Matix Composite
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 34~40
Conductive metal matrix composite(MMC) material of 30% silicon carbide particulated based on aluminum matrix was machined by die sinking electrical discharge machining(EDM) process according to different current and duty factor for reverse polarity of electrode. Material removal rate(MRR) was examined by process under various operation conditions. The surface morphology was evaluated by surface roughness parameter and scanning electron microscopy(SEM) research. The MRR was suddenly increased over 11 ampere of current, and it was slightly changed over 0.3 of duty factor. The maximum surface roughness of EDMed surface was affected by the duty factor. The SEM photograghs of EDMed surface showed wide recast distribution region of melting materials as increased of current and duty factor.
A Study on Sound Radiation from Isofropic Plates Stiffened by Symmetrical Reinforced Beams
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 41~50
The detemination of sound pressure radiated from peoriodic plate structures is fundamental in the estimation of noise levels in aircraft fuselages and ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model for predicting the sound radiated by a vibrating plate stiffened by periodically spaced orthogonal symmetric beams subjected to a sinusoidally time varying point load is developed. The plate is assumed to be infinite in extent, and the beams are considered to exert both line force and moment reactions on it. Structural damping is included in both plate and beam materials. A space harmonic series representation of the spatial variables is used in conjunction with the Fourier transform to find the sound pressure in terms of harmonic coefficients. From this theoretical model. the sound pressure levels on axis in a semi-infinite fluid (water) bounded by the plate with the variation in the locations of an external time harmonic point force on the plate can be calculated efficiently using three numerical tools such as the Gauss-Jordan method, the LU decomposition method and the IMSL numerical package.
On-line Balancing of a Ultra-high speed Rotor with Residual Unbalance
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 51~57
In order to minimize vibration problems of rotating machinery rotors have been assembled through balancing machines. Since perfect balancing is impossible, residual unbalances cause serious vibration while the rotor is in high speed region. To minimize unbalance effects of magnetic bearing systems (AMB) during rotation on-line balancing methodology was studied. Unbalances were considered as disturbances of the system. The disturbance observer was used to estimate unbalance force from measurable state and input variables. Balancing inputs computed according to LQR and outputs of the observer were applied to eliminate unbalances during high speed rotation of the AMB. the effectiveness of the on-line balancing was verified through numerical simulations.
Evaluation Method of Bonded Strength Considering Stress Singularity in Adhesively Bonded Joints
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 58~68
Advantages of adhesively bonded joints and techniques of weight reduction have led to increasing use of structural adhesives such as LSI(large scale integration) package, automobile, aircraft in the various industries. In spite of such wide applications of adhesively bonded joints, the evaluation method of bonding strength has not been established. Stress singularity occurs at the interface edges of adhesively bonded joints and it is required to analyze it. In this paper, the stress singularity using 2-dimensional elastic boundary element method (BEM) with the changes of the lap length and adhesive for single lap joint was analyzed, and experiments of strength evaluation were carried out. As the results, the evaluating method of bonding strength considering stress singularity at interface edges of adhesively bonded joints and stress intensity factor of interface crack have been proposed in static and fatigue test.
A Study on the monitoring of tool wear in face milling operation
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 69~74
In order to monitor the tool wear in milling operation, cutting force is measured as the tool wear increased. The digital signal processing methods are used to detect the tool wear . As AR parameter extract the feature of tool wear , it can be used as input parameter of pattern classifier. The FFT monitor the tool wear exactly , but it can not do real time signal processing. The band energy method can be used to real time monitoring of tool wear ,but int can degrade the exact monitoring.
A study on the Mechanical Characteristics by the Internal Quality of Connecting Rod Materials for Trucks
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 75~81
We have studied internal quality including chemical compositions, microscopic structure and nonmetallic inclusion of test materials. We have analyzed tensile strength value, hardness value, impact value etc. In analyzing internal quality, all of the test materials showed typical ferrite+pearlite structure. But nonmetallic inclusion showed oxide and sulfide inclusions in medium carbon steels, and sulfide inclusion is S-free cutting steels. In ca+ S-free cutting steels, the calcium aluminate and sulfide complex inclusion had low-melting points as deformation of sulfide and oxide inclusion is existed. It was found that tensile strength and hardness give maximum value in medium carbon steels, where as minimum in Ca + -free cutting steels. But values of elongation, reduction of area impact are reverse. Fracture surface of impact specimen is ductile in free cutting steels but brittle in medium cabon steels.
A Study on Measuring of Motion Accuracy of NC Machine Tools(No.1) -about Measuring of Linear Cycle Positioning Accuracy of NC Lathe
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 82~88
It is very important to test linear cycle positioning accuracy of NC lathes as it affect all other machines machined by them in industries. For example, if the linear positioning accuracy of x or z-axis directions is bad, the size of works will be wrong and the change-ability will be bad in the assembly of machine parts. In this paper , measuring systems are organized to measure linear displacement of ATC(Automatic tool changer) of NC lathe using laser interferometer, magnescale and tick pulses coming out from computer in order to get data at constant time intervals from the sensors, And each set of data gotten from test is expressed to a plots by computer treatment and the results of linear positioning error motion is estimated to numerics by statistical treatments.
Influence of Chucking Conditions on the Chatter Vibration Commencing Point in Turning
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 89~94
With increasing demands on automatic and high-capability manufacturing, the dynamic performance of machine tools becomes more and more important. In this paper, the correlation between dynamic compliance of the cutting system and the commencing point of chatter vibration in turning is checked by impulse excitation method and cutting tests for some cutting system. The correlation between chucking conditions of workpiece and the commencing point of chatter vibration is clarified, and it is proven that there is a mutual relations between them. Chatter vibration commenced at certain level of dynamic compliance of the cutting system regardless of the kind of the system. It shows the possibility of dynamic performance test of a lathe by means of impulse excitation method.
Operation control method for multiple objectives on multiple stages automated machining /assembly systems
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 95~103
This paper is concentraed on a study of operation for multiple objectives in a automated manufacturing system with multiple machining cells . Largest Sum Processing-time First(LSPF) was developed in order to minimize makespan, mean flowtime and maximize mean utilization and compare with Ho and Chang's algorithm(HC) and Hunsucker and Shah's algorithm(HS). The results show that LSPF provides better soutions than HC at 78.2% and than HS at 67.8% of total problems to frequency . LSPF reduces 5.8% of makespan by HC and 22.1% of the value by HS and curtails 15.8% , 7.5% of mean flowtime by receptive algorithms(HC, HS). And mean utilization is also higher about 5.5% than HC and HS.
An analysis Inverse Kinematics for Real Time Operation of Industrial Robot
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 104~111
This study solves the inverse kinematics problem of industrial FANUC robot. Because every joint angle of FANUC robot is dependent on the position of end-effector and the direction of approach vector, arm metrix T6 is very complicated and each joint angle is a function of other joint angles. Therefore, the inverse kinematics problem can not be solved by conventional methods. Noticing the fact that if one joint angle is known, the other joint angles are calculated by the algebraic methods.
1 is calculated using neumerical analysis method, and solves inverse kinematics problem. This proposed method, in this study, is more simpler and faster than conventional methods and is very useful in the real-time control of the manipulator.
A study on the dressing time monitoring method of grinding wheel in surface grinding
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 112~118
In surface grinding, the contact between the grinding wheel and workpiece introduce heat and resistance, which restrict the self-dressing of the grits and result in burrs and cracks on the workpiece. Therefore, before or during the grinding operation, it is necessary to self-dress the grinding wheel for more accurate performance. In order to determine the dressing time monitoring method of grinding wheel in surface grinding, a three-dimensional computer simulation of the grinding operation has been attempted based on the contact mechanism and surface-shaping system between the grinding wheel and the workpiece. The optimal dressing time is determined based on the grain wear and work surface roughness.
A study on the Effects of the Bearing Parameters on the Main Spindle Design of Machine Tool
Yeo, Eun Gu ; Kim, Yeop Rae ; Han, Gang Geun ; Park, Myeon Ung ; Yu, Heon Il ; Lee, Yong Sin ;
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 119~119
The purpose of this study is to investigate the effects of operation factors of a typical main spindle system on the efficiency of machine tool. In this study. both static and dynamic analysis of typical main spindle system of the machine tool are performed using a finite element method. These finite element results are then used to predict the bearing stiffness. the amount of heat generation as well as the bearing life in the spindle system. Effects of material type of ball-bearing. bearing-lubricant type and main spindle bearing preload are examined.
Development of a Customized CAM System for CNC Glass Scribing Machine
Journal of The Korean Society of Manufacturing Technology Engineers, volume 7, issue 1, 1998, Pages 126~134
In order to increase the modeling power and productivity of CAD/CAM systems, demands for customization of CAD/CAM system increased. Customization of a CAM system involves making it easier to learn and use, adding new modeling features not supported in a general purpose CAM system, and providing parametric inputting mechanism. A customization from a commercial CAM system (OMEGA) has implemented for two dimensional free curve CNC glass scribing machine of medium size company in Cheonan. A CAD technician who has no CAM experience can operate this customized CAM system satisfactorily.