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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
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Volume & Issues
Volume 19, Issue 12 - Dec 2002
Volume 19, Issue 11 - Nov 2002
Volume 19, Issue 10 - Oct 2002
Volume 19, Issue 9 - Sep 2002
Volume 19, Issue 8 - Aug 2002
Volume 19, Issue 7 - Jul 2002
Volume 19, Issue 6 - Jun 2002
Volume 19, Issue 5 - May 2002
Volume 19, Issue 4 - Apr 2002
Volume 19, Issue 3 - Mar 2002
Volume 19, Issue 2 - Feb 2002
Volume 19, Issue 1 - Jan 2002
Selecting the target year
Technical Trends of Micro Factory
Park, Jong-Gwon ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 7~14
Development of Microfactory System for Future Industry
Gang, Jae-Hun ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 15~22
Micro Machine Tools and Micro Machining
Bae, Yeong-Ho ; Kim, Hui-Sul ; Go, Tae-Jo ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 23~30
Micro-Measurement and Machining Complexation
Lee, Chae-Mun ; Im, Tae-Sun ; Jeong, U-Seop ; Lee, Deuk-U ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 31~36
A Study on the Vibration Characteristics of Rotor System with Fluid Film Bearing
Park, Seong-Hwan ; O, Taek-Yeol ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 37~44
The dynamic behavior of rotor-bearing system has been investigated using finite element method. A procedure is presented for dynamic modeling of rotor-bearing system which consists of shaft elements, rigid disk, flexible bearing and support structure. A finite element model including the effects of rotary inertia, shear deformation, gyroscopic moments is developed. Linear stiffness and damping coefficients are calculated for 2 lobe sleeve bearing. The whirl frequency, mode shape, stability and unbalance response of rotor system including effects of bearing coefficient and support structures are calculated.
Combined Optimal Design of Structure-Control Systems by Sliding Mode Control
Park, Jung-Hyeon ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 45~51
To achieve the lightweight and robust design of a structure, it is requested to design a structure and its control system simultaneously, which is called as the combined optimal design. A constant-cross-sectional area cantilever beam was chosen as an example for the applying the optimum design method. An initial load and a time varying disturbance were applied at the free end of the beam. Sliding mode control was selected due to its insensitiveness to the disturbance compared with other modes. It is known that the sliding mode control is robust to the disturbance and the uncertainty only if a matching condition is met, after giving a switching hyper plane. In this study, the optimum method was used for the design of the switching hyper plane and the objective function of the optimum switching hyper plane was assumed to be the objective one of the control system. The total weight of the structure was treated as a constraint and the cross sectional areas of the beam were considered as design variables, which means a nonlinear programming problem. The sequential linear programming method was applied to solve it. As a result of the optimum design, the effect of attenuating vibrations has been improved obviously. Moreover, lightweight design of the structure became possible from the relationship of the weight of the structure and the control objective function.
Thermo-mechanical Characteristics of High Temperature NITINOL Shape Memory Alloy
Yun, Seong-Ho ; Sridhar Krishnan ; Scott R. White ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 52~59
The thermo-mechanical characteristics of high temperature NITINOL shape memory alloy were evaluated using DSC with small samples and DMA with three-point bending specimens. The shape memory alloy of 54.4Ni/45.5Ti wt.% was used so that the phase transformation temperatures were in the range of 50~11
. Two types of sample were tested in the experiments corresponding to as-received and annealed conditions. Simple beam bending theory was used to calculate the dynamic moduli of the shape memory alloy. According to the results, a large discrepancy in transformation temperatures was found between DSC and DMA techniques. Annealing treatment was found to suppress the R-phase transformation during cooling and the secondary plateau in the austenite transformation. Such a heat treatment was also significantly influenced to raise the transformation temperatures and the moduli of the shape memory alloy.
A Study on the Optimal Structural Design using FEM for Micro Stage
Kim, Jae-Yeol ; Gwak, Lee-Gu ; Han, Jae-Ho ; Kim, Hang-U ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 60~65
For optimal design of micro stage, we measured the displacement of piezoelectric transducer that was based on voltage value. And the micro stage was analyzed using FEM with displacement data including voltage value of piezoelectric transducer. For verification of analysis results, the displacements were measured by using Laser-interferometer. And researchers confirmed to propriety on design of micro stage with FEM, we obtained 3.5% error rate between measurement results and analyzing results.
Path Optimization Using an Genetic Algorithm for Robots in Off-Line Programming
Gang, Seong-Gyun ; Son, Gwon ; Choe, Hyeok-Jin ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 66~76
Automated welding and soldering are an important manufacturing issue in order to lower the cost, increase the quality, and avoid labor problems. An off-line programming, OLP, is one of the powerful methods to solve this kind of diversity problem. Unless an OLP system is ready for the path optimization in welding and soldering, the waste of time and cost is unavoidable due to inefficient paths in welding and soldering processes. Therefore, this study attempts to obtain path optimization using a genetic algorithm based on artificial intelligences. The problem of welding path optimization is defined as a conventional TSP (traveling salesman problem), but still paths have to go through welding lines. An improved genetic algorithm was suggested and the problem was formulated as a TSP problem considering the both end points of each welding line read from database files, and then the transit problem of welding line was solved using the improved suggested genetic algorithm.
A Study on the Die Casting of Mg-9Al-1Zn Alloy for Air Bag Case
Kim, Sun-Ho ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 77~83
Magnesium alloys casting are gaining increased acceptance in the automotive and electronic industeries and die casting is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of Mg-9Al-lZn alloy fabricated by die casting process for development of air bag case. The microstructure of die casted specimen were composed of pro-eutectic magnesium solid solution and
(Mg17Al12) precipitates. The tensile strength of as-fabricated Mg-9Al-lZn alloy revealed 231.4MPa. It was found that Mg-9Al-lZn alloy have good corrosion resistance in electrochemical polarization test.
The Characteristics of Fatigue Cracks Emanating from Small Hole Defects Located Opposite Position of the Shaft Cross Section
Song, Sam-Hong ; An, Il-Hyeok ; Lee, Jeong-Mu ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 84~91
The shaft with the circular cross section have symmetric structural combination parts to keep the rotating balance. Hence the crack usually emanate from symmetric combination parts due to the stress concentration of these parts. In this study to estimate the fatigue behavior of symmetric cracks, the fatigue test was performed by using rotary bending tester and the specimen with symmetric defects in circular cross section. From the facts the characteristics of crack initiation and propagation on the symmetric surface cracks in circular cross section was examined. Also we observed the internal crack using oxidation coloring and investigated the fatigue behavior using the relationship between surface crack and internal crack. As a result of fatigue lift of symmetric cracks was reduced to 35% compared to single crack’s. We examined the characteristics of fatigue behavior in element with symmetric cracks using internal crack propagation rate and maximum stress intensity factor range obtained from approximation method.
Indirect Method for Measurement of Tool Edge Roughness in flat End Mill
Kim, Jeon-Ha ; Gang, Myeong-Chang ; Kim, Jeong-Seok ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 92~98
End mill is an essential tool to generate complex surface in workpiece and it has been developed with various materials and tool shapes. The most important factor to evaluate the performance of end mill is still the wear characteristics of flank face. In addition to the flank wear, the tool edge roughness generated by the chipping is another important factor in aspects of material property and machinability evaluation and affects the quality of machined surface. Up to now, there is no direct method for measurement of tool edge roughness. In this study, the tool edge roughness of flat end mill is indirectly measured along the axial direction of workpiece. The theoretical equation is derived in consideration of tool geometry. Finally, the optimal conditions to measure the tool edge roughness by the proposed method are presented through the theoretical review and experimental identification.
A Study on Improvement of Accuracy using Geometry Information in Reverse Engineering of Injection Molding Parts
Kim, Yeon-Sul ; Lee, Hui-Gwan ; Hwang, Geum-Jong ; Gong, Yeong-Sik ; Yang, Gyun-Ui ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 99~106
This paper proposes an error compensation method that improves accuracy with geometry information of injection molding parts. Geometric information can give an improved accuracy in reverse engineering. Measuring data can not lead to get accurate geometric model, including errors of physical parts and measuring machines. Measuring data include errors which can be classified into two types. One is molding error in product, the other is measuring error. Measuring error includes optical error of laser scanner, deformation by probe forces of CMM and machine error. It is important to compensate these in reverse engineering. Least square method (LSM) provides the cloud data with a geometry compensation, improving accuracy of geometry. Also, the functional shape of a part and design concept can be reconstructed by error compensation using geometry information.
Speed Sensorless Torque Monitoring of Induction Spindle Motor using Graphical Programming
Park, Jin-U ; Gwon, Won-Tae ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 107~113
To monitor the torque of an induction motor using current, rotating speed has been measured and used to calculate the slip angular velocity. Additional sensor, however, can cause extra expense and trouble. In this paper, a new algorithm is proposed to monitor the torque of vector controlled induction motor without any speed measuring sensor. Only stator current is measured to estimate the magnetizing current which is used to calculate flux linkage, rotor velocity and motor torque. Graphical programming is used to implement the suggested algorithm and to monitor the torque of an induction motor in real time. To solve the fluctuation problem of estimated torque caused from instantly varying rotating speed of an induction motor, the rotating speed is reconstructed based on the measured current signals. From several experiments, the proposed method shows a good estimation of the motor torque under the normal rotational speed.
Position/Force Control of Constrained Flexible Manipulators Using Structural Compliance Modeling
Kim, Jin-Su ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 114~119
The aim of this paper is to clarify the structural compliance of the constrained flexible manipulator and to develop the force control algorithm by using the compliance of the links. The proposed structural compliance control consists of the position control to utilize a flexible manipulator model (considering the compensation for the elastic deflection of links) and the passive force control to utilize the rigid manipulator model (without considering the compensation for the elastic deflection of links). We present the experimental results for the case when applying the only position control, and when applying the structural compliance control. Finally, a comparison between these results is presented to show the performance of our method.
Integrated Structure and Controller Design of Single-Link Flexible Arm for Improving the Performance of Position Control
Lee, Min-U ; Park, Jang-Hyeon ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 120~129
An integrated structure and controller design approach for rotating cantilever beam is presented. An optimization method is developed for improving positioning performance considering the elastic deformations during high speed rotation and adopting the beam shape and the control gains as design variables. For this end, a dynamic model is setup by the finite element method according to the shape of the beam. The mass and stiffness of the beam are distributed in such a way that the closed-loop poles of the control system should be located leftmost in the complex s-plane. For optimization method, the simulated annealing method is employed which has higher probability to find the global minimum than the gradient-based down-hill methods. Sequential design and simultaneous design methods are proposed to obtain the optimal shape and controller. Simulations are performed with new designs by the two methods to verify the effectiveness of the approach and the results show that the settling time is improved for point-to-point position controls.
On the Analysis of Dynamic Characteristics of Pipe Supporting Hydraulic Snubber in Electric Power Plant with State-space Model and Impulse Testing
Lee, Jae-Cheon ; Im, Mun-Hyeok ; Hwang, Tae-Yeong ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 130~138
This paper presents the modeling and analysis of dynamic characteristics of hydraulic snubber in electric power plant. The nonlinear state-space model of 14th order to describe the dynamics of the snubber was established by Simulink. The simulation results show that the hydraulic snubber reacts as like the conventional shock absorbers against the high pulse shock load. The snubber also shows the peculiar characteristics to the small step load, which temporarily lock the control valves up, however maintain same steady-state pressures of all internal chambers in the long run. Two case studies for the analysis of the snubber were addressed. Practical pulse testing method was also proposed to identify the frequency response characteristics of the snubber.
Development of Motion Capture System
U, Jeong-Jae ; Choe, Hyeong-Sik ; Kim, Yeong-Sik ; Jeon, Dae-Won ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 139~146
We developed a motion capture system to utilize informations on the human walking motion. The system is composed of the mechanical and electronic devices to obtain the joint angle data and the software to analyze the obtained data and to transform the data into the input for a biped walking robot. The mechanical system is composed of a pair of links with 3 revolute joints, on which potentiometers are attached on joint axes to sense rotation angles. Analog signals from potentiometers are transformed into the digital data through the low pass filter and the A/D converter, and then which are stored at the computer. We analyzed the walking characteristics by applying FFT to the digital data, and then performed a 3-D computer simulation using the data. Finally, We apply the processed data to a biped walking robot.
Determination of Process Parameters in Stereolithography using Neural Network
Lee, Eun-Deok ; Sim, Jae-Hyeong ; Baek, In-Hwan ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 147~155
In the stereolithography process, the accuracy of product depends on laser power, scan speed, scan width, scan pattern, layer thickness, resin characteristics and so on. Therefore, appropriate process parameters are required for an accurate prototype. This paper presents a method to determine the key process parameters, i.e., laser scan speed, hatching space, and layer thickness based on scan length, scan area, and layer slope. In order to determine these parameters, three neural networks are employed to represent operator’s experience and knowledge. Optimum values on scan speed, hatching space and layer thickness are recommended to improve the surface roughness and build time on the developed SLA machine.
A Study on the Correlation between Temperature and CMP Characteristics
Gwon, Dae-Hui ; Kim, Hyeong-Jae ; Jeong, Hae-Do ; Lee, Eung-Suk ; Sin, Yeong-Jae ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 156~162
There are many factors affecting the results of CMP (Chemical Mechanical Polishing). Among them, the temperature is related to the removal rate and WIWNU (Within Wafer Non-Uniformity). In other words, the removal rate is proportional to the temperature and the variation of temperature distribution on a pad affects the non-uniformity within a wafer. In the former case, the active chemistry improves the rate of chemical reaction and the removal rate becomes better. But, there are not many advanced studies. In the latter case, a kinematical analysis between work-piece and pad can be obtained. And such result analysed from the mechanical aspect can be directly related to the temperature distribution on a pad affecting WIWNU. Meanwhile, the temperature change affects the quantities of both slurry and pad. The change of a pH value of the slurry chemistry due to a temperature variation affects the surface state of an abrasive particle and hence the agglomeration of abrasives happens above the certain temperature. And the pH alteration also affects the zeta potential of a pad surface and therefore the electrical force between pad and abrasive changes. Such results could affect the removal rate and etc. Moreover, the temperature changes the 1st and 2nd elastic moduli of a pad which are closely related to the removal rate and the WIWNU.
Dynamic Model and Analysis of a Vacuum Circuit Breaker Mechanism for High-Speed Closing and Opening Simulations
An, Gil-Yeong ; Kim, Su-Hyeon ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 163~170
The dynamic model of a high-speed vacuum circuit breaker mechanism with spring-actuated cam and linkage is derived to simulate the high-speed closing and opening operations. Its validation for an analysis of high-speed motion behavior is checked through experiments. The characteristics of the friction on the camshaft are investigated using the nonlinear pendulum experiment. The parameters of the friction model are estimated using the optimization technique. The analysis exhibits that the friction of the pendulum depends on stick-slip, Stribeck effect and viscous damping. Comparing simulation results with actual responses using a high-speed camera, the appropriateness of derived dynamic models for the rapid closing and opening operations is shown. The spring motion, which has much influence on the closing responses, is observed.
Inertia Force Problem and Nozzle Contact Mechanism on Linear Motor Drive Injection Molding Machine
Bang, Yeong-Bong ; Yun, Deung-Jin ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 171~177
This paper presents the inertial force problem of ultrahigh-speed injection molding machine using linear motors, and presents its solutions. To make very thin products by injection molding, very high injection speed is required, and linear motors are used for this purpose. But direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of the inertia force as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic leakage. In this paper, two solutions are proposed for this inertia force problem. One is the mechanical cancellation of the inertia force, and the other to increase the nozzle contact force. With the latter solution, the stationary platen bending worsens, so a new nozzle contact mechanism is also proposed, which can prevent the stationary platen bending.
Development of Steering Control System for UCT (Unmanned Container Transporter) Using Robust Control
Jeong, Seung-Gwon ; Kim, In-Su ; Kim, Chang-Seop ; Choe, Ju-Yong ; Yun, Gang-Seop ; Lee, Man-Hyeong ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 178~186
In this study, the steering control system for UCT (unmanned container transporter) was developed using MR (Magnetoresistive) sensors. The MR and magnet sensors are used for the lane detecting system. The robust control theory is used for the design of the steering controller to reduce the uncertainties of the road. The performance of the robust steering controller is compared in simulations and tests using the existing PD controller of the UCT.
A Study on Machining Electrode for LED Mold with Shaped End-Mill
Kim, Hyeong-Chan ; Lee, Hui-Gwan ; Hwang, Geum-Jong ; Gong, Yeong-Sik ; Yang, Gyun-Ui ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 187~194
A study on machining electrode for LED (Light Emitted Diode) mold with shaped end-mill is presented. The electrode machining by shaped end-mill has been used for maximizing the productivity in manufacturing semiconductor mold. However, it has not been researched systematically for many difficulties such as the making of shaped end-mill, generation of tool path due to distinctive tool geometry, and so on. Tool path is generated on geometry of the shaped end-mill and cutting force to provide accurate and efficient machining of electrode. The verification program can drive enhancement of productivity, selecting cutting conditions from experiment function of cutting force. Also, compensation of tooling and maching error can make the electrode accurately by modifying tool path. Therefore, the research on machining with shaped end-mill can contribute to enhancement of accuracy and productivity in building semiconductor mold.
A Study on Ultra Precision Machining for Aspherical Surface of Optical Parts
Lee, Ju-Sang ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 195~201
This paper deals with the precision grinding for aspherical surface of optical parts. A parallel grinding method using the spherical wheel was suggested as a new grinding method. In this method, the wheel axis is positioned at a
/4 from the Z-axis in the direction of the X-axis. An advantage of this grinding method is that the wheel used in grinding achieves its maximum area, reducing wheel wear and improving the accuracy of the ground mirror surface. In addition, a truing by the CG (curve generating) method was proposed. After truing, the shape of spherical wheel transcribed on the carbon is measured by the Form-Talysurf-120L. The error of the form in the spherical wheel which is the value
inferred from the measured profile data is compensated by the re-truing. Finally, in the aspherical grinding experiment, the WC of the molding die was examined by the parallel grinding method using the resin bonded diamond wheel with a grain size of ＃3000. A form accuracy of 0.16
P-V and a surface roughness of 0.0067
Ra have been resulted.
Development of Spur Gear Design Software using Tooth Profile Modification
Kim, Tae-Wan ; Hwang, Jin-Yeong ; Jo, Yong-Ju ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 202~211
The basic concept of 'tooth profile modification' to change a part of the involute profile to reduce the load in that area and appropriate profile modifications can help gears to run quietly and resist scoring, pitting and tooth breakage. In this study, the modification of tooth profile to make a smooth transmission of the normal loads in spur gears has been developed. The modified tooth profile has been determined by the total deflection at contact points. We use the AGMA Standard to design basic gear profile. We also developed a gear design program using tooth profile modification.
A Study on Nano-polishing of Injection Molds using Fixed Abrasive Pad
Choe, Jae-Yeong ; Kim, Ho-Yun ; Park, Jae-Hong ; Jeong, Hae-Do ; Seo, Heon-Deok ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 212~220
The finishing process for die and mold manufacturing is very important because it influences the final quality of products. Injection molds need higher quality surface than general purpose dies and molds. Conventional polishing can not make mold surface down to nanometer roughness efficiently because of their loading and glazing. This paper focused on the development of fixed abrasive pad using water swelling mechanism of polymer binder network. Self-conditioning was recognized as the long term polishing stabilization tool without any loading or glazing because water makes fixed abrasives free by swelling of the pad. Consequently, stable nano-polishing process has been applied on the injection mold, from the experimental results with polished surface roughness of Ra 15.1nm on STD-11 die steel.
Characteristics of Environment-friendly Semi-dry Turning
Lee, Jong-Hang ; Lee, Sang-Jo ; Lee, Seok-U ; Choe, Heon-Jong ;
Journal of the Korean Society for Precision Engineering, volume 19, issue 10, 2002, Pages 221~226
As environmental restriction has continuously become more strict, machining technology has emphasized on development of environment-friendly technologies. In cutting technology, it has been well recognized that cutting fluids might have undesirable effects on workers health and working environment and, hence, recently there have been numerous attempts to minimize harmful effects of cutting fluids on environments. To minimize the use of cutting fluids in machining, conventional cutting fluids have been replaced with the technologies of pressurized cold air and minimum quantity lubrication (MQL). Compared with milling, turning is continuous cutting process, where tools are continuously heated up and lack of lubricity could lead to tool wear and deteriorated surface roughness. In this work, it has been investigated how tool wear and surface roughness could be affected by cutting conditions, supply and cooling methods. The experimental results show that MQL technology is able to minimize conventional cutting fluids.