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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 29, Issue 12 - Dec 2012
Volume 29, Issue 11 - Nov 2012
Volume 29, Issue 10 - Oct 2012
Volume 29, Issue 9 - Sep 2012
Volume 29, Issue 8 - Aug 2012
Volume 29, Issue 7 - Jul 2012
Volume 29, Issue 6 - Jun 2012
Volume 29, Issue 5 - May 2012
Volume 29, Issue 4 - Apr 2012
Volume 29, Issue 3 - Mar 2012
Volume 29, Issue 2 - Feb 2012
Volume 29, Issue 1 - Jan 2012
Selecting the target year
A Fundamental Study on the Design of Two-axis Drive Manipulator for Laser-assisted Machining
Kim, Dong-Hyeon ; Cha, Na-Hyeon ; Kim, Tae-Woo ; Lee, Choon-Man ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 813~817
DOI : 10.7736/KSPE.2012.29.8.813
Laser assisted machining (LAM) is machining method that performs a machining for workpieces using laser beam preheating. LAM is in the early stage of its applications and has only been used in limited fields including turning, planning and micro end-milling throughout the world. LAM system should be able to move to the laser radiation direction and to rotate on a tool path for machining of complex shapes. A laser module with two-axis manipulator is designed in this study. It has been performed static structural analysis and shape modification of the manipulator. As the results of shape modification it has been obtained better results than the initial model. These results will be able to use in development of the two-axis manipulator.
Prediction of Necking in Tensile Test using Crystal Plasticity Model and Damage Model
Kim, Jong-Bong ; Hong, Seung-Hyun ; Yoon, Jeong-Whan ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 818~823
DOI : 10.7736/KSPE.2012.29.8.818
In order to predict necking behaviour of aluminium sheets, a crystal plasticity model is introduced in the finite element analysis of tensile test. Due to the computational limits of time and memory, only a small part of tensile specimen is subjected to the analysis. Grains having different orientations are subjected to numerical tensile tests and each grain is discretized by many elements. In order to predict the sudden drop of load carrying capacity after necking, a well-known Cockcroft-Latham damage model is introduced. The mismatch of grain orientation causes stress concentration at several points and damage is evolved at these points. This phenomenon is similar to void nucleation. In the same way, void growth and void coalescence behaviours are well predicted in the analysis. For the comparison of prediction capability of necking, same model is subjected to finite element analysis using uniform material properties of polycrystal with and without damage. As a result, it is shown that the crystal plasticity model can be used in prediction of necking and fracture behavior of materials accurately.
A Study on the Design of Cooling Channels of Injection Mould to Manufacture a Flat Part with a Partly Thick Volume
Ahn, Dong-Gyu ; Park, Min-Woo ; Kim, Hyung-Soo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 824~833
DOI : 10.7736/KSPE.2012.29.8.824
The shrinkage and the warpage of the moulded part are influenced by the design of the product and injection mould. In a flat part with a partly thick volume, the warpage of the flat part is created from the difference of the shrinkage between thin and thick regions. The warpage of the flat part with a partly thick volume can be reduced by a proper design of the cooling system in the injection mould. The goal of this paper is to design properly cooling channels of injection mould to manufacture a flat part with a partly thick volume. The conformal cooling channel is adopted to improve cooling characteristics of a region with the thick volume. The linear cooling channels are assigned to the other region. The proper design of the conformal cooling channels is obtained from three-dimensional injection molding analysis for various design alternatives. The moulding characteristics of the designed mould with both conformal and linear cooling channels are compared to those of the mould with linear cooling channels from viewpoints of temperature, shrinkage and warpage of the moulded part using numerical analysis. Injection mould with both conformal and linear cooling channels for the flat part with a partially thick volume is fabricated. In addition, injection moulding experiments are performed using the fabricated mould. From the results of the injection moulding experiments, it has been shown that the designed mould can successfully fabricate the flat part with a partially thick volume.
Current Trends of Vibration-Assisted Machining in Micro/Nano Scales
Lee, Moon-Gu ; Jeon, Yong-Ho ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 834~839
DOI : 10.7736/KSPE.2012.29.8.834
Recently, mechanical components with miniaturized size, complex shape and fine surface are on demand from industries such as mobile electronics, medical devices and defense. The size of them is smaller than several millimeters, the shape has micro-holes, curve, or multi-step and the surface is mirror-like. This features are not able to be machined with the conventional machining, therefore electro-discharge machining (EDM), cutting, and laser machining have been applied. If the technologies are assisted by vibration, high aspect ratio and good surface are to be achieved. In this paper, prior and current researches of vibration-assisted machining are reviewed. Machining mechanisms with vibration-assisting are explained, their effects are shown, and vibrating apparatuses are discussed. Especially, comparison between with and without vibration assisting is presented. This review shows the vibration-assisted machining is effectively fabricate the components with small and complicated shape and fine surface finish.
A Study on Development of Automotive Panel of Bumper Reinforcement with High Strength Steel Using Roll Forming Process
Jung, Dong-Won ; Kim, Dong-Hong ; Kim, Bong-Chun ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 840~844
DOI : 10.7736/KSPE.2012.29.8.840
Roll forming process is a sheet metal forming process where the forming occurs with rolls in several steps, often from an undeformed sheet to a product ready to use. And each pair of forming rolls installed in a forming machine operates a particular role in making up the required final cross-section. This process used to many industry manufactures and recently apply to automotive industry. This study, FEM simulation applied bumper reinforcement using SHAPE-RF software and analyzed about total effective strain, longitudinal strain, thickness according to the roll-pass.
Development of Diaphragm-type Stylus Probe for Ultra-precision On-machine Measurement Application
Lee, Jung-Hoon ; Lee, Chan-Hee ; Choi, Joon-Myeong ; Kim, Ho-Sang ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 845~852
DOI : 10.7736/KSPE.2012.29.8.845
The diaphragm-type stylus probe was developed for ultra-precision on-machine measurement (OMM) application. This probe is equipped with two diaphragms which are parallel and one capacitive sensor is used for detecting the vertical motion of end tip in the stylus when it is contacted to the optical freeform surface. For better performance of proposed probes, several design parameters such as axial stiffness and the lateral deformations were investigated with finite element analysis techniques. To verify the feasibility, the profiles of the master sphere ball were measured on the ultra-precision milling machine. The measurement results show that the proposed probe can calculate the radius of the circle within the accuracy of 0.1
for the ultraprecision optical surface.
Measurement of Temperature Field in the Primary Deformation Zone in 2-D Orthogonal Machining Using IR (Infra-Red) Thermography
Kim, Myung-Jae ; Jung, Hyun-Gi ; Hwang, Ji-Hong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 853~862
DOI : 10.7736/KSPE.2012.29.8.853
The present study develops a method for directly measuring the temperature field in the primary deformation zone with a high spatial resolution during 2-D orthogonal machining. This is enabled by the use of a high-speed, charge-coupled device (CCD) based, infra-red (IR) imaging system which allows characteristics of the temperature field such as the location and magnitude of the highest temperature and temperature gradient in the primary deformation zone to be identified. Based on these data, the relation between the machining temperature and the cutting conditions is investigated.
Analysis for the Squareness Measurement using Laser Interferometer
Lee, Dong-Mok ; Lee, Hoon-Hee ; Yang, Seung-Han ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 863~872
DOI : 10.7736/KSPE.2012.29.8.863
The squareness measurement of driving axes of a machine tool is very important to evaluate the performance of the machine. Laser interferometer measurement system is one of the most reliable equipment to measure the squareness. However, squareness measurement using laser system with an optical square result in restriction of straightness optics setup and Abbe's offset. This offset combines with angular errors during the motion of an axis to cause Abbe's error. In addition, the difficulty in optical square setup causes restriction of other optics and limitation of measurable range. In this paper, mathematical approaches are presented to eliminate the Abbe's error and to estimate squareness for full range by using the best fit of straightness data measured without an optical square. Experiments for squareness measurement of 3 axis machine tool were conducted and the proposed techniques were used for squareness evaluation with elimination of Abbe's error and squareness estimation for the full travel range.
A Spatial Stability of the Conductive Rod Conveyed by Double Electrodynamic Wheels
Jung, Kwang-Suk ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 873~878
DOI : 10.7736/KSPE.2012.29.8.873
Putting a conductive rod between rotating axial electrodynamic wheels composed of repetitive permanent magnets, three-axial magnetic forces generate on the conductive rod. It is possible to levitate and transfer the rod on space with the forces. However, the forces vary in direction and magnitude for a position of the rod between the electrodynamic wheels. Thus, the position influences the stability of the rod also. To guarantee the stability of a levitated object, the force acting on the object should have negative stiffness like a spring. So, we analyze the stable operating range of the conductive rod levitated by the axial wheels with the commercial finite element tool in this paper. Specially, as the pole number and the radial width of permanent magnets has much influence on the generated force and thereby the stable region, their sensitivities are analyzed also. The analytic result is compared with experimental result.
Manufacturing Cost Optimization of Ultrasonic Horn for Flip-chip Bonding using Tolerance Design
Kim, Jong-Hyok ; Kwon, Won-Tae ; Lee, Soo-Il ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 879~886
DOI : 10.7736/KSPE.2012.29.8.879
The ultrasonic horn used for bonding of flip chip has been designed to vibrate at a natural frequency. The ultrasonic horn must be manufactured accurately in physical terms, because the small change of mechanical properties may result in the significant change of natural frequency. Therefore, tight tolerance is inevitable to keep the natural frequency in acceptable range. However, since tightening of the tolerance increases the manufacturing cost significantly, trade-off between the cost and accuracy is necessary. In this research, an attempt was made to design the ultra sonic horn within acceptable natural frequency while the manufacturing cost was kept as low as possible. For this purpose, among the 18 tolerances of physical terms of the ultrasonic horn, the most important 4 factors were selected using Taguchi method. The equation to relate those main factors and the natural frequency was made using response surface method. Finally, optimal design scheme for minimum manufacturing cost without a loss of performance was determined using SQP method.
A Method of Lamb-Wave Modes Decomposition for Structural Health Monitoring
Jun, Yong-Ju ; Park, Il-Wook ; Lee, U-Sik ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 887~895
DOI : 10.7736/KSPE.2012.29.8.887
Lamb waves have received a great attention in the structural health monitoring (SHM) societies because they can propagate over relatively large distances in wave guides such as thin plates and shells. The time-of-flights of Lamb waves can be used to detect damages in a wave guide. However, due to the inherent dispersive and multi-mode characteristics of Lamb waves, one must decompose the Lamb wave modes into the symmetric and anti-symmetric modes for SHM applications. Thus, this paper proposes a decomposition method for the two-mode Lamb waves based on two rules: the group velocity ratio rule and the mode amplitude ratio rule. The group velocity ratio rule means that the ratio of the group velocities of fundamental symmetric and anti-symmetric modes is constant, while the mode amplitude ratio rule means that the magnitude of the fundamental symmetric modes of all measured response signals should be always larger than those of the anti-symmetric mode once the input signal is applied so that the magnitude of fundamental symmetric mode of excited Lamb-wave is larger than that of anti-symmetric mode, and vice versa. The proposed method is verified through the experiments ducted for an aluminum plate specimen.
Investigation of Development of Bumper Back-Beam Using a Thermoplastic Polyolefin
Ahn, Dong-Gyu ; Kim, Se-Hun ; Park, Gun-Sung ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 896~905
DOI : 10.7736/KSPE.2012.29.8.896
Recently, the application of the plastic material to automotive components and structures has steadily increased to satisfy demands on the saving of overall weight and the improvement of energy efficiency. The objective of this paper is to investigate the development of a bumper back-beam using a thermoplastic olefin (TPO). The bumper back-beam was designed to be manufactured from the injection molding process. In order to obtain a proper design of the bumper back-beam, three-dimensional finite element analyses were performed for various design alternatives. Stress-strain curves for different strain rates were measured by high speed tensile tests of the TPO to consider strain rate effects in the FEA. The influence of the sectional shape and the rib formation on the contact force-intrusion curves, the deflection and the energy absorption rate of the bumper back-beam was examined. From the results of the examination, a proper design of the bumper back-beam was acquired. The bumper back-beam consisting of TPO was fabricated from the injection moulding process and the vibration welding. Pendulum crash tests were carried out using the fabricated bumper back-beam. The results of the tests showed that the designed bumper back-beam can satisfy requirements of the federal motor vehicle safety standard (FMVSS). Through the comparison of the previously designed bumper back-beam with the newly designed bumper back beam, it was noted that the weight of the designed bumper back-beam is lighter than that of the previously designed bumper back beam by nearly 16 %. In addition, it was considered that the newly designed bumper back beam can improve recycling of the bumper back-beam.
Measurement of a Six-degree-of-freedom Dynamic Characteristics using Angle Sensor-Implemented Grating Interferometry
Lee, Cha-Bum ; Kim, Gyu-Ha ; Lee, Sun-Kyu ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 906~912
DOI : 10.7736/KSPE.2012.29.8.906
This paper presents the new method for a six-degree-of-freedom (DOF) motion measurement and those dynamic characterizations in an ultraprecision linear stage using angle sensor-implemented grating interferometry. It consists of a diffractive optical element, a corner cube, four separate two-dimensional position sensitive detectors, four photodiodes and auxiliary optics components. From the previous study, it was confirmed that the proposed optical system could measure a six-DOF motion error in a linear stage. In this article, six-DOF motion dynamic characteristics of the stage were investigated through the step response and with respect to the conditions with a different speed of a slide table. As a result, the natural frequency and damping ratio according to a six-DOF direction was obtained. Also, it was seen that the speed of slide table had an significant effect on a six-DOF displacement motion, especially, X, which was considered as the effect of friction mechanism and local elastic mechanical deformation in a slide guide.
Micro-particles in a Nanoliter Droplet Dispensed by a Pneumatic Dispensing System and Its Measurement
Lee, Sang-Min ; Kim, Joon-Won ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 913~919
DOI : 10.7736/KSPE.2012.29.8.913
This paper presents results for dispensing and measuring micro-particles using a pneumatic dispensing system. Particle-suspended liquid droplets were dispensed and analyzed quantitatively at various particle concentrations and applied pressures. By using a developed experimental setup, the number of particles and the particle volume ratio in sequentially dispensed droplets were measured. Hydrophilic and hydrophobic surfaces were tested to find a suitable surface for counting the number of particle. It was confirmed that the dispensed particles concentrated into the center of the droplet on the smooth CD surface after evaporation of liquid. As the applied positive pressure increased, the number of particles per droplet increased consistently and the volume fraction of particles remained constant.
Investigation into the Fabrication of Micro-scale Winkles using Repetitive Contact-and-open Method
Kim, Seong-Jin ; Park, Sang-Hu ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 8, 2012, Pages 920~926
DOI : 10.7736/KSPE.2012.29.8.920
Wrinkling is a common phenomenon in nature and the shape of a wrinkle can be defined using characteristic dimensions such as pitch, length, amplitude, and density etc. Wrinkle structure can be utilized in various research fields, and especially it has special characteristics when it used in applications of heat transfer; a wrinkly surface has the effect to promote turbulent flow and increasing surface area. However, the generation of wrinkle structures in somewhat regular is not easy. Till now, there are some research works focused on realization of wrinkles in micro scale. However, most of the processes generally requires high precision equipments and high costs, and also there is a limitation to generate the wrinkles in a large area. In this study, we propose a novel method named as a RCO (repetitive contact-and-open) process to fabricate wrinkle structure with low cost and relative easy way. Using the RCO, we fabricated micro-corrugate structures successfully. From the experimental results, we found out the process parameters of RCO, and showed the possibility of RCO to be used in real applications.