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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Precision Engineering
Journal Basic Information
Journal DOI :
Korean Society of Precision Engineering
Editor in Chief :
Volume & Issues
Volume 18, Issue 12 - Dec 2001
Volume 18, Issue 11 - Nov 2001
Volume 18, Issue 10 - Oct 2001
Volume 18, Issue 9 - Sep 2001
Volume 18, Issue 8 - Aug 2001
Volume 18, Issue 7 - Jul 2001
Volume 18, Issue 6 - Jun 2001
Volume 18, Issue 5 - May 2001
Volume 18, Issue 4 - Apr 2001
Volume 18, Issue 3 - Mar 2001
Volume 18, Issue 2 - Feb 2001
Volume 18, Issue 1 - Jan 2001
Selecting the target year
Tendency of PVD coating technology on Metal cutting tools
Kim, Jong-Seong ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 11~17
Industrial use of physical vapor deposition(PVD) has been widely expanded during last two decades, and in the mean time plasma assistance in PVD has become an essential tool in preparing compound films with dense microstructure. The principles of electron beam-based plating, balanced and unbalanced magnetron sputtering and cathodic arc deposition. consisting three basic configuration of plasma assisted PVD(PAPVD)process, were reviewed. Recent technical development in PVD coating process were discussed. This paper tries to show tendency for developing new coating film on cutting tools.
High Speed Machining & Technology of Tooling for Die and Mold Making
Choe, Chang-Hui ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 18~23
Study on the Design of End Mill Geometry
Go, Seong-Rim ; Lee, Sang-Gyu ; Bae, Seung-Min ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 24~31
PID Control of a Synchronous Rotor System Vibration with Active Air Bearing
Gwon, Dae-Gyu ; Lee, Yeong-Chun ; Lee, Seong-Cheol ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 32~39
This paper presents the synchronous vibration control of a rotor system using an Active Air Bearing(AAB). In order to suppress the synchronous vibration, it is necessary to actively control the air film pressure or the air film thickness. In this study, active pads are used to control the air film thickness. Active pads are supported by the pivots containing piezoelectric actuators and their radial positions can be actively controlled by applying voltage to the actuators. Disturbances and various kinds of external force can cause the shaft vibration as well as the change of the air film thickness. The dynamic behaviors of a rotary system supported by two tilting-pad gas bearings and its active stabilization using the tilting-pads as actuators are investigated numerically. The PID controller is applied to the tilting-pad gas bearing system with three pads, two of which contain piezoelectric actuators. To test the vapidity of the theoretical method, the performance of this control method is evaluated through experiments. The experimental results show the effectiveness of the control system for suppressing the unbalanced response of the rigid modes.
Sensor Structure and Signal Processing System for Precision Optical Displacement Measurement
O, Se-Baek ; Kim, Gyeong-Chan ; Kim, Su-Hyeon ; Gwak, Yun-Geun ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 40~47
Optical measurement methods make it possible to detect object displacements with high resolution and noncontact measurements. Also, they are very robust against EMI noises and have long operation range. An optical triangulation sensor is one of widely used displacement measurement sensors for its sub-micron resolution, fast response, simple structure, and low cost. However. there are several errors caused by inclinations of a surface. speckle effects, power fluctuations of light sources, and noises of detectors. In this paper, in order to minimize error effects, we performed error analysis and proposed a new structure. Then, we setup a new modeling method and verify it through simulations and experiments. Based on the new model. we propose a new sensor structure and establish design criteria. Finally, we design a signal processing system to overcome a resolution-limited problem of light detectors. The resolution of the proposed system is 0.2
in 5mm operating range.
A Study on the Active Balancing Method for High Speed Spindle System Using Influence Coefficient
Kim, Bong-Seok ; Kim, Jong-Su ; Lee, Su-Hun ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 48~53
In order to increase productivity and efficiency, high-speed rotating machines become popular these days. The high-speed rotating machine is likely to vibrate and cause machine failure even though it has small unbalance. Therefore, a balancing technique is studied in this paper. Off-line balancing methods are inadequate to solve unbalance vibration problem occurring in the field due to flexible rotor effect, faster tool change, and shorter spin-up and down, etc. An active balancing is suggested to allow re-balancing of the entire rotating assembly in the machine when a tool is changed. This paper shows how to identify the dynamics of the system using influence coefficient and suggest an active balancing technique based on influence coefficient method for high-speed spindle system.
Development of Variable Lamination Manufacturing(VLM) Process and Apparatus by Using Expandable Polystyrene Foam
Ahn, Dong-Gyu ; Lee, Sang-Ho ; Yang, Dong-Yol ; Shin, Bo-Sung ; Park, Seung-Kyo ; Lee, Yong-Il ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 54~63
Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of a part due to layer-by-layer stacking, low build speed caused by point-by-point or line-by-line solidification to build one layer, and additional posts processing to improve surface roughness, so high cost is required to introduce and to maintain the RP apparatus. The objective of this study is to develop a new RP process, Variable Lamination Manufacturing by using expandable polystyrene foam sheet as part material(VLM-S), and to design an apparatus for implementation of the process. So, the process parameters and design criterions of the apparatus were defined and the techniques were proposed to satisfy the design criterion. Based on the results, a knob-shape, pyramid shape. and a solid block were fabricated on the apparatus in which unit shape part(USP) was generated for building each layer.
Software Development for Automatic Generation of Unit Shape Part for Variable Lamination Manufacturing Process
Lee, Sang-Ho ; Kim, Tae-Hwa ; An, Dong-Gyu ; Yang, Dong-Yeol ; Chae, Hui-Chang ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 64~70
In all the Rapid Prototyping (RP) techniques, the computer-aided design (CAD) model of a three-dimensional part is sliced into horizontal layers of uniform, but not necessarily constant, thickness in the building direction. Each cross- sectional layer is successively deposited and, at the same time, bonded onto the previous layer. The stacked layers form a physical part of the model. The objective of this study is to develop a software for automatic generation of unit shape part(USP) for a new RP process, Variable Lamination Manufacturing using the linear hotwire cutting technique and expandable polystyrene foam sheet as part material(VLM-S). In order to examine the applicability of the developed software to VLM-S, USPs of general three-dimensional shapes, such as an auto-shift lever knob and a pyramid shape were generated.
A Study of the Thermal Analysis of Horizontal Fillet Joints by Considering the Bead Shape in GMA Welding
Jo, Si-Hun ; Kim, Jae-Ung ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 71~78
In GMA(Gas Metal Arc)Welding, the weld size that is a locally melted area of a workpiece is one of the most important considerations in determining the strength of a welded structure. Variations in the weld power and the welding heat flux may affect the weld pool formation and ultimately the size of the weld. Therefore, an accurate prediction of the weld size requires a precise analysis of the weld thermal cycle. In this study, a model which can estimate the weld bead geometry and a method for thermal analysis, including the model, are suggested. In order to analyze the weld bead geometry, a mathematical model was developed with transformed coordinates to apply to the horizontal fillet joints. A heat flow analysis was performed with a two dimensional finite element model that was adopted for computing the base metal melting zone. The reliability of the proposed model and the thermal analysis was evaluated through experiments, and the results showed that the proposed model was very effective for predicting the weld bead shape and good correspondence in melting zone of the base metal.
Feedback Techniques for Minimizing Reaction Forces in Flexible Structures
Kim, Joo-Hyung ; Kim, Sang-Sup ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 79~86
A method for actively minimizing dynamic reaction forces in a flexible structure subject to persistent excitations is presented. One difficulty with the method, however, is that forces and moments do not converge as quickly as displacements in mathematical discretization of continuous systems, so a controller based on a truncated model of a continuous system can produce poor results. A technique using residual flexibility matrix is presented for correcting the truncated force representation. A controller designed for reaction force minimization, using the residual flexibility matrix, is applied to a model of a flexible structure, and the results are presented. Implications of various reaction force penalty combinations on the resulting control performance are also discussed.
Dynamic Analysis of Asymmetric Bending-torsion Coupled Beam Using Exact Dynamic Elements
Hong, Seong-Uk ; Gang, Byeong-Sik ; Jo, Yong-Ju ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 87~95
Although asymmetric beams are widely used in industry, few research results are available on the dynamic modeling and analysis of structure including asymmetric beams. Asymmetric beams cause complicated vibration phenomena due to the inherent bending-torsion coupled vibration. In this paper, an exact dynamic element matrix for the bending-torsion coupled vibration of asymmetric beam is derived. The application of the derived exact dynamic element matrix is demonstrated by some illustrative examples wherein the natural frequencies by the proposed modeling method are compared with those available in the literature. Another numerical example is also illustrated which deals with a general beam with joints. The numerical study shows that the exact dynamic element model is useful for the dynamic analysis of asymmetric bending-torsion coupled beams.
Cutting Torque Control in Drilling Part 1 : Design of a Cutting Torque Controller
O, Yeong-Tak ; Gwon, Won-Tae ; Ju, Jong-Nam ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 96~106
As the drilling depth increases, the cutting torque increases and fluctuates, which can lead to the machine tool vibration, severe tool wear, and catastrophic tool breakage. Hence, cutting torque control is very important to improve productivity in drilling. In this paper, a PID controller was designed to control the drilling torque. The plant including the feed drive system, cutting process and spindle drive system was modeled for controller design. The Ziegler-Nichols method was used to determine the controller gain and control action times and the root locus plot was used to tune the controller gain for a certain cutting condition. Also, suggested was a simple method to obtain the tuned controller gain for an arbitrary cutting condition not using the Ziegler-Nichols method and the root locus plot. The performance of the designed controller and the effect of controller gain tuning were verified from experiments.
Cutting Torque Control in Drilling Part 2 : Drilling Torque Control Using Spindle Motor Current and Its Effect on Drill Flank Wear
O, Yeong-Tak ; Kim, Gi-Dae ; Ju, Jong-Nam ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 107~115
Drilling torque was measured indirectly using the spindle motor current and controlled in real time through feedrate manipulation in a machining center. The PID controller designed in the previous paper was applied to drilling torque control. A series of cutting experiments were performed for various cutting conditions. Experimental results showed that the drilling torque was well regulated at a given reference level by feedrate manipulation in all cutting conditions. The increase in the cutting torque and temperature according to the increase in machining depth was suppressed and the risk of the drill failure and the drill flank wear were reduced remarkably through cutting torque control. Moreover, the suggested cutting torque control system doesn\`t disturb the cutting process and is practical for industrial environment. Therefore, the proposed culling torque control system will contribute to productivity improvement in drilling process.
A Study on Dynamic Characteristics of a Rotor-Bearing System Supported by Actively Controlled Fluid Film Journal Bearing
No, Byeong-Hu ; Kim, Gyeong-Ung ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 116~121
The paper presents the dynamic characteristics of a rotor-bearing system supported by an actively controlled hydrodynamic journal bearing. The proportional. derivative and integral controls are adopted for the control algorithm to control the hydrodynamic journal bearing with an axial groove. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than conventional analysis, which uses the Reynolds condition. The speed at onset of instability of a rotor-bearing system is increased by both proportional and derivative control of the bearing. The proportional control increases the stability threshold without affecting the whirl ratio. However, for the derivative control of the bearing, increase of stability threshold speed is accompanied by a parallel reduction of the whirl ratio. The integral control has no effect on stability characteristics of hydrodynamic journal bearing. The PD-control is more effective than proportional or derivative control. Results 7how the active control of bearing can be adopted for the stability improvement of a rotor-bearing system.
A Study on the Friction and Wear Characteristics of Carbon Fiber Reinforced Plastics by Surface Modification
O, Seong-Mo ; Lee, Bong-Gu ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 122~128
The objective of the present study was to investigate the characteristics of the friction and wear according to the amount of ion-irradiation for the carbon fiber reinforced plastic(CFRP). Unidirectional carbon fiber reinforced composites were fabricated with epoxy resin as a matrix and carbon fiber as a reinforcement, and its surface was modified by the ion-assisted reaction. When the amount of ion-irradiation was
, the friction coefficients of composites were about 0.1 and the wear mode was stable, whereas, the friction coefficient of non-treatment composites were about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was
, the friction coefficients were higher rather than that of
. Consequently, the amount of ion-irradiation was not in proportion to the friction coefficients, and it was conformed that the optimal conditions would exist between broth of them.
Implementation of Assembly Line and Line Balancing to Improve Assembly Productivity-A Case Study
Mok, Hak-Su ; Jo, Jong-Rae ; Pyo, Seung-Tae ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 129~138
The paper presents an implementation procedure of assembly line for ABS motor, which is composed of four subassemblies-yoke, grommet, housing and armature. The characteristics of ABS motor and its assembly processes are analysed, and the automation possibility of each process is examined in order to decrease assembly time. The assembly machines and facilities are then selected for automatic assembly, and the layout of the selected facilities is determined. Finally, task allocation of each worker is achieved by assembly line balancing to increase assembly productivity and efficiency. The line efficiency is also analyzed using simulation.
Effects of Cutting Conditions on Surface Roughness in Turning
Lee, Sin-Yeong ; Kim, Hong-Nam ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 139~149
The effects of the cutting conditions on the surface roughness of workpiece in turning were studied in this paper. The workpieces made of carbon steel SM20C and SM45C were tamed without the support of the tailstock center. Cutting conditions were changed in three or flour steps in each parameter and cutting fluid was used. The surface roughness results of tests were measured and the effects of the cutting conditions were analyzed by the method of analysis of variance. The summary of the experimental research is as follows. The main parameters were cutting speed, fred-rate, depth of cut, and the interactions between speed and fled-rate, speed and depth of cut, and fred and depth of cut. As cutting speed increased, surface roughness showed lower value. The surface roughnesses of feed-rate 0.102 mm/rev and 0.147 mm/rev were better than those of feed-rate 0.05 mm/rev and 0.2 mm/rev.
Estimation and Experimental Verification of Grinding Wheel Wear in Surface Grinding Process
Ju, Gwang-Hun ; Lee, Eung-Suk ; Kim, Hyeon-Su ; Hong, Seong-Uk ; Park, Cheon-Hong ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 150~156
This paper deals with the theoretical estimation and its experimental verification of grinding wheel wear in surface grinding process. A theoretical formulation is provided to predict the grinding wheel wear in surface grinding. To validate the theoretical prediction, the grinding wheel wear is measured by using a laser scanning micrometer. The associated surface roughness and grinding farce are also investigated both theoretically and experimentally. Through a series of simulations and experiments, it is shown that the predictions are in good agreement with the experimental results.
Application of Piezoceramic Actuator to the Inch-Worm
Kim, In-Su ; Lee, Hong-Sik ; Song, Jun-Yeop ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 157~163
This paper presents the new linear notion device so called \"inch-werm\" which gets large displacement by incrementally summing small displacements of PZT actuators. Dynamic stiffness of inch-worm is generally low compared to its driving condition due to the requirement of inch-worm like small size and light weight. This low stiffness may degenerate the positional precision of inch-worm. An inch-worm is realized using three PZT actuators, a monolithic moving device and a guide way frame. Finite element method and experimental approach are used to analyse the static and dynamic motion of the designed inch-worm. Command reference input is shaped to reduce the residual vibration of inch-worm. The practical feasibility of inch-worm is also examined by running tests.ing tests.
A Study on the Development of Intelligent Supplementary Feature Designer(ISFD) in Injection Molding
Gang, Seong-Nam ; Heo, Yong-Jeong ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 164~173
The configuration of injection molded part can be classified into primary feature and supplementary feature. Even though supplementary features such as ribs, snap fits and bosses make mold more complicated, which cause the increasement of the mold cost, supplementary features should be attached to primary features because of assembly, reinforcement, moldability and other functional purposes. But it is not easy for novice designers to design them appropriately because of the profound knowledge related to Injection molding. In this paper, the intelligent design tool called ISFD(Intelligent Supplementary Feature Designer) which supplies easy, simple, time and cost-effective design method has been studied and developed. A knowledge-based design system is a new tool which enables the concurrent design and CIM with integrated and balanced design decisions at the initial design stage of injection molding.
The Design and Performance Test of Tracking Actuator for NFR system
Kim, Gi-Hyeon ; Lee, Mun-Gu ; Gwon, Dae-Gap ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 174~181
Nowadays, the improvement and development of Multi-media and information & communication technology is rapidly processed. They need large data storage capacity. So that, many studies and researches in data storage have been carried out. According to them, the data storage capacity has been increased. But the limitation of storage capacity is happened for several problems. One of them is spot & pit size in optical and magnetic data storage and another is the resolution of actuators. The problems in spot & pit size are covered by new data storage methods-- for examples, AFM(Atomic Force Microscopy), MO(Magneto-optical) system, and NFR(Near-Field decoding) system etc. But the resolution limit of an actuator was not developed and doesn\`t follow up the development of spot & pit size. Because of them, we should improve a resolution of an actuator. Especially, in this paper an actuator if studied and designed for NFR (in using SIL(Solid Immersion Lens) system. It is a dual stage actuator, which consists of a Fine actuator and a Coarse actuator. and should desire 100nm accuracy. Its actuating force generation method is VCM(Voice Coil Motor). The Fine actuator is composed of 4-leaf springs and a bobbin wrapped by coil. The Coarse actuator has Coils and 3-Roller bearings. Also, The Characteristics of designed actuator for NFR system is estimated by Sine-Swept mode and LDV(Laser Doppler Vibro-meter).
A Study on Elliptical Cup Drawing of YOKE Products for Automobile
Park, Dong-Hwan ; Bae, Won-Rak ; Park, Sang-Bong ; Gang, Seong-Su ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 182~192
During the deep drawing process an initially flat blank is clamped between the die and the blank holder after which the punch moves down to deform the clamped blank into the desired shape. In general, sheet metal forming may involve stretching, drawing, bending or various combinations of those basic modes of deformation. The deformation problems of sheet metal working involve non-linearity in geometry and material. In this work, The punch load and thickness strain of electro-galvanized sheet steel (SECD) for elliptical deep drawing are examined under the various process conditions including, punch shape radius, die shape radius. The changes of punch load and thickness strain distribution of the deformed elliptical cup are affected by the size of each die shape radius.
Motion Analysis and Dynamic Characteristics of the Concrete Floor Finishing Robot with Deformable Trowels
Kim, Jin-Ho ; Sin, Dong-Heon ;
Journal of the Korean Society for Precision Engineering, volume 18, issue 8, 2001, Pages 193~200
Recently, the concrete floor finishing robot, which can be used for flattening and smoothing the concrete floor, has been developed in Korea and Japan. While the previous research assumes that the concrete floor is deformable and the trowel is rigid in modeling the concrete floor finisher, we assume that the concrete floor is rigid and the trowel is deformable. Based on this assumption, we derived the equations of motion and found the convergent velocity of the concrete floor finisher using the computer simulation. From these results, we can understand the relationship between the motion characteristics and the design and control parameter of the robot.