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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 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
Influence of Stripping and Counter Punching Forces on Fine Blanking Characteristics of T-shaped Products
J.H. Kim ; J.G. Ryu ; D.H. Kim ; J.H. Lee ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 15~21
This study is performed for investigating the effects of stripping and counter punching forces on shearing characteristics in fine blanking of T-shaped products, such as camber, burr-height and dimensional accuracy, etc by experiments. Conventional hydraulic press is used for experiments so that both the stripping force and counter punching force can be arbitrarily adjusted by another hydraulic unit connected to the fine blanking die. Specimens are selected as hot rolled steel sheet and carbon steel sheet commonly used in auto- mobile company. Based on the experimental results, both the dimensional accuracy and the burr height are not influenced by the stripping and counter punching forces, wherease the camber height representing dish- shaped deflection is much influenced by them, it can be seen through this study that the finely cut surface of T-shaped blank can be obtained even in conventional hydraulic press if additional equipments and specially designed die are employed.
Fatigue Life Estimation Using the Multi-Axial Multi-Point Load Counting Method under Variable Amplitude Loading
Lee, W.S. ; Lee, H.W. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 22~27
In general, the load which acts on the structure is almost independent of time in many locations. In this case. It is difficult to estimate the life with the service load history, because the structure is on the multi- axial and multi-point loading states. In this study, the service load of the excavator which is widely used in industry field was calculated using measured cylinder pressures and displacements. The fatigue life was estimated using the multi-axial and multi-point load counting method. Service load history of 4 pin joint which act independently each other is yielded by mult-axial and multi-point load counting method. The stress spectrum is yielded by superposition of the results of FEM stress analysis applied unit load. Palm- gren-Miner's cumulative Damage is 0.000804 for Von Mises equivalent stress sequence by one side fillet weld S-N curve. This result agress with Bench test results. As a result of this study, the fatigue life esti- mation using the multi-axial and multi-axial and multi-point load counting method is useful.
Dynamic Behaviour Analysis of Shock Absorber on Vehicle
Park, J.W. ; Shin, S.Y. ; Lee, S.B. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 28~36
Even if the shock absorber is developed to Variable S/V or Active S/A, it is necrssary to construct database or bulid the dynamic performance characteristic program of Oil S/A. Since both Variable S/A and Active S/A are based on the principle of Oil S/A. To obtain the design technique of Oil S/A, we model the daping mechanism and characteristics of an Oil S/A whose performance was testified. And then it is analyzed the dynamic behaviour characteristics of damping mechanism.
A Study on the Laser Lamination Joining of Silicon Steel Sheets with Die
Kang, H.S. ; Kang, I.T. ; Jun, T.O. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 37~43
The technology of Laser lamination joining of silicon steel sheets has been studied in this paper. Conventional sheets lamination process does not meet the requirments for the improvement electric parts performance. In response to this, a new Laser spot joining method has been developed. This study performs the Laser spot lamination joining while synchronizing the sillicon steel sheets in the dies with the press movement. Several conclusions have been drawn in this paper. Effects of beam focus, power, atmosphere gas and press oil etc.
A Study on the Analysis of Surface Characteristics According to intermittent Ratio of Discontinuous Grinding Wheel with Multi-Porous Grooves
Kim, J.D. ; Y.H. Kang ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 44~51
Crinding of stainless steel, aluminium alloy, copper alloy, and titanium alloy are difficult to obtain high quality finish, because they have the mechanical properties such as low hardness, high toughness. The low hardness and the high toughness result in the loading of wheel and the poor surface finish. In order to perform the grinding operations for these sorts of materials easily, the discontinuous grinding wheel wiht multi-porous grooves has been newly developed. The multi-porous grooves inthe discontinuous grinding wheel were formed during grinding wheel manufacturing process. In this paper, discontinuous grinding wheels having intermittent ratio 0.66, 0.81 and number of grooves 18,32 have been manufactured and grinding surface characteristics of these grinding wheels for SUS304 have been analyzed. Discontinuous grinding temperature according to intermittent ratiohas been also estimated by simulation. The discontinuous grinding wheels increase the grinding performance considerably. It is desirable to use the discontinuous grinding wheel in grinding the materials with high efficiency and accuracy.
A Study on the Proper Scope for Pressure Angle, Ratio of Tooth Number & Radius of Curvature in Non-Circular Gears
Park, S.H. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 52~63
Non-circular gear has a good velocity ratio in high speed and heavy load without any slip, moreover, it can transmit various motion, using simpler structure than link and cam, automation mechainism. In case of designing and manufacturing non-circular gear. I suggest one of references in applying non-circular gear to industrial plant, and suitable range of application by pressure angle curvature and angle ratio
Develpment of Automated Stress Intensity Factor Analysis System for Three-Dimensional Cracks
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 64~73
A Comparative Study on the International Technology Levels and R&D Cooperation Capabilities of Mechanical Engineering and Other Technologies by Delphi Method
Y.J. Kwon ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 74~82
We provide a set of information on technologies to draw meaningful action plans for the internationalization on National R&D activities. In this study, we employed a modiffed Delphi method to evaluate levels of our technological capabilities and developed countries as well. We investigated technology acquis- tion methodologies, technology characteristics and various aspects of international cooperation in terms of technology. Then, we analyzed final responses of participants (i.e., the third round results of Delphe method) to see the correlation among various factors in developing technologies through international R&D cooperation. The technology classification used in this research was developed by STEPI (Science and Technology Policy Institute). In conclusion, levels of our technologies were investigated to be between the stage of imi- tating/absorbing advanced thechnologies and the stage of digesting acquired technologies. Especially, com- paring with other technologies, mechanical engineering was evaluated to be almost near the stage of digesting acquired technology(the middle level stage of technology). Our overal technological capabilities were evaluated to be 40 .approx. 60% of top level countries.
A Study on Fatigue Crack Retardation and Retardation Mechanism in Variable Loading
S.H. Song ; Y.K. Kwon ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 83~89
In order to study on fatigue crack retardation and retardation mechanism in variable loading, the effects of crack tip branching in fatigue crack growth retardation were examined. The characteristics of crack tip banching behavior was considered to micro structure. It was examined that the variation of crack tip branching angle. Crack tip branching was observed along the grain boundary of ferrite and pearlite structure. It was found that the abanching angle ranges from 25 to 53 degrees. Using the finite element method, the variable of crack driving force to branching angle was examined. The effective crack driving force (
) decreased as the braching angle increases. The rate of decrease was 33% for the kinked type and 29% for the forked one. It was confirmed that the effect of crack tip branching is a very important factor in fatigue crack growth retardation. Therefore, crack branching effect should be considered building the hypoth- etical model to predict crack growth retardation.
Time-optimal Control Utilizing Beural Networks
Park, W.W. ; J.S. Yoon ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 90~98
A time-optimal control law for quick, strongly nonlinear systems has been developed and demonstrated. This procedure involves the utilzation of neural networks as state feedback controllers that learn the time-optimal control actions by means of an iterative minimization of both the final time and the final state error for the systems with constrained inputs and/or states. A neural identifier or a genetic algorithm identifier could be utilized for modeling the partially known systems and the unknown systems. The nature of neural networks as a parallel processor would circumvent the problem of "curwe of dimensionality". The control law has been demonstrated for both a torque input motor and a velocity input motor identified by a genetic algorithm called GENOCOPed GENOCOP
A Study on Micromachining Using Stereolithographic Rapid Prototyping System
Kim, D.W. ; H.C. Chae ; Kim, N.G. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 99~105
Recently, with a great interest in micromachine, it is more and more important to promote the way of manufacturing micromachine. The silicon process or the LIGA process was the main method to manufacture micromachine in the past. But, these manufacturing method was 2.5-dimensinal, there was the limit in manufacturing perfect 3-dimensional structure micromachine. In this study, we developed the rapid prototyping system for micromachining and tested its property. We also realized .mu. m-order manu- facturing and 3-dimensional structure processing. The results showed the possibility of micromachining with the rapid prototyping system
Modified Time Delay Control for Servo with Friction
Park, J.H. ; Kim, Y.M. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 106~113
A new algorithm based upon TDC (Time Delay Control) is proposed to improve the robustness of TDC performance in systems where the stick-slip friction is strong. Experiments were performed at the different levels of friction. The reponses of the TDC and the modified TDC were compared each other, and against those of a PID controller with an anti-windup. The results show that the TDC and the modified TDC equally perform better than the PID, and that the modified TDC performs consistently well even with variations in the friction level while the TDC does not.
Crack Growth Behavior in the Integrally Stiffened Plates(ll) - Experimental Evaluation of SIF-
H.W. Rhee ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 114~120
To assess the validity of the previously computed finite element analysis results, the photoelastic experiment was carried out to determine stress intensity factors for crack originating from thin section of integrally stiffened plates having discontinuous thickness interface. The stress intensity factors were deter- mined by using linear slope method of photoelastic data. Results are presented as variable thickness geometry factor.
, for various crack lengths and thickness ratios. The experimental values of F/ sub IV/are compared with 3-D finite element analysis results. The correlation between experimental values and analysis results is resonably good.
A Variance Learning Neural Network for Confidence Estimation
Y.B. Cho ; D.G. Gweon ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 121~127
Multilayer feedforward networks may be applied to identify the deterministic relationship between input and output data. When the results from the network require a high level of assurance, consideration of the stochastic relationship between the input and output data may be very important. Variance is one of the effective parameters to deal with the stochastic relationship. This paper presents a new algroithm for a multilayer feedforward network to learn the variance of dispersed data without preliminary calculation of variance. In this paper, the network with this learning algorithm is named as a variance learning neural network(VALEAN). Computer simulation examples are utilized for the demonstration and the evaluation of VALEAN.
The Analysis on the Error of Diverging Beam and Cylindrical Surface in Holographic Interferometer for Measuring out-of-plane Displacement.
Y.J. Kang ; S.J. Moon ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 128~134
Holographic interferometry is a useful whole-field nondestructive tesing method for measuring deformations and vibrations of engineering structure. In practical way most holographic interferometer uses a diverging beam, a point light source. When an oject is relatively small, the optical arrangement using a collimated light source has no difficulty technically but for a large object the collimated beam connot be applied anymore practically. In this paper we calculate the error of measured displacement from the sensi- tivity vector dominated by the geometry of optical arrangement for holographic interferometer and show the result with 2-D plots. A plane surface and a cylindrical surface were chosen as objects to be measured and the results from the cases of a diverging and a collimated beams were compared and analyzed.
Damage Characteristics of Quasi Isotropic Composite Laminates Subjected to Low Velocity Impact
Kim, J.H. ; J.C. Jeon ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 135~141
Low velocity impact test and compressive residual strength test after impact were performed by using Hercules AS4/3501-6[45/0/-45/90]
laminated plate to investigate the low velocity impact damage behavior and the post-impact strength degradation on orthotropic composite laminate plate. Due to the lateral impact losd, the load path showed "" shape according to the laminate central deflection. Damage in a laminate occurs by inclined matrix crack at the damage initiation load stage and vertical matrix crack, occurs on the outer surface. Evaluating the compressive residual strength after the low velocty impact test, it could be found that there is a transient range where the compressive residual strength drop suddenly in the initial damage which is in the matrix crack range and the initial delamination area. is in the matrix crack range and the initial delamination area.
A Study on the Forging of Cylindrical Parts with Internal Serrations
Park, J.C. ; Cho, H.Y. ; Min, G.S. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 6, 1997, Pages 142~148
In this paper, forging of internal triangular and involute serrations are analyzed by upper bound method. Kinematically admissible velocity fields for half pitch of the serration were proposed. It was assumed that the shape flow surface during forging is a straight line perpendicular to plane of symmetry. Using the suggested velocity fields, forging loads and relative pressures were calculated by numerical method. Experiments were carride out with commercial AI 2024 aluminium alloy. As a result, the calculated solutions are good agreement with experimental results, so it is useful to predict the loads for forging of internal serrations.l