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Volume 21(8); August 2004

Articles
High Precision Measurement of Rotational Accuracy
Wei Gao, Chun Hong Park
J. Korean Soc. Precis. Eng. 2004;21(8):7-13.
Published online August 1, 2004
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Precision Measurement Technology in Assembly Process of NC
Ki Tae Kim, Seong Jun Moon
J. Korean Soc. Precis. Eng. 2004;21(8):14-18.
Published online August 1, 2004
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Examples of Performance Estimation on the Feed Sytem of Precision Machine Tools
Chun Hong Park, Joo Ho Hwang
J. Korean Soc. Precis. Eng. 2004;21(8):19-26.
Published online August 1, 2004
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A Study on the Machinability of Electroless Nickel by the Ultra-Precision Diamond Turning
Woo Soon Kim, Dong Hyun Kim, Yoshiharu Namba
J. Korean Soc. Precis. Eng. 2004;21(8):27-33.
Published online August 1, 2004
The ultra-precision cutting is a key technique for the manufacture of optical components such as aluminium mirrors, electroless nickel mirror, plastic mirror in a variety of advanced science and technology applications. The paper presents experimental results of ultra-precision diamond turning of electro less nickel materials. In general, the cutting condition such as feed rate and depth of cut, have effect on the surface roughness in ultra-precision diamond turning. To obtain an optimal cutting condition, we studied the effect of the cutting speed, the tool length, the tool nose radius, the feed rate and depth of cut on the surface roughness. So, the relationship of the surface roughness and cutting condition has been clarified. From the experimental results, the machined surface roughnesses were obtained less than 1㎚ rms.
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Nano-scale Precision Polishing Characteristics using a Micro Quill and Magnetic Chain Structure
Sung-Jun Park, Byung-Woon Ahn, Sang-Jo Lee
J. Korean Soc. Precis. Eng. 2004;21(8):34-42.
Published online August 1, 2004
A new polishing technique for three dimensional micro/meso-scale parts is suggested using a micro quill and a magnetic chain structure. The principle of this method is to polish the target surface with the collected magnetic brushes at a micro tool by the non-uniform magnetic field generated around the tool. In a typical magnetic abrasive finishing process magnetic particles and abrasive particles are unbonded each other. But, to finish the three dimensional small parts bonded magnetic abrasive have to be used. Bonded magnetic abrasives are made from direct bonding, and their polishing characteristics are also examined. Alumina, silicon carbide and diamond micro powders are used as abrasives. Base metal matrix is carbonyl iron powder. It is found that bonded magnetic abrasives are superior to unbonded one by experiment. Finally, the polished surface roughness is evaluated by atomic force microscope.
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Machining Characteristics in High Speed Endmill Operation Considering Clearance Angle
Joung Nam Park, Sung Lim Ko
J. Korean Soc. Precis. Eng. 2004;21(8):43-49.
Published online August 1, 2004
The objective of this research is to investigate the effect of clearance angle on cutting performance in high speed end milling operation. The tool geometry parameters have complex relationship with cutting process parameter. In order to explain the effect of clearance angle, 2D turning operation in lathe and end milling operations are performed. Tools with different clearance angles are manufactured. Cutting forces, machining accuracy and tool life are examined according to the change of clearance angle. As clearance angle increases, cutting force decreases and machining accuracy improves. But it has been proved that there exists the optimal clearance angle according to the diameter of end mill for maximum tool life which is measured by frank wear.
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Dimensional Analysis for the Front Chassis Module in the Auto Industry
Dong-Mok Lee, Seung-Han Yang
J. Korean Soc. Precis. Eng. 2004;21(8):50-56.
Published online August 1, 2004
The directional ability of an automobile has an influence on driver directly, and hence it must be given most priority. Alignment factors of automobile such as the camber, caster and toe directly affect the directional ability of a vehicle. The above mentioned factors are determined by the pose of interlinks in the assembly of an automobile front chassis module. Measuring the position of center point of ball joints in the front lower arm is very difficult. A method to determine this position is suggested in this paper. Pose estimation for front chassis module and dimensional evaluation to find the rotational characteristics of front lower arm were developed based on fundamental geometric techniques. To interpret the inspection data obtained for front chassis module, 3-D best fit method is needed. The best fit method determines the relationship between the nominal design coordinate system and the corresponding feature coordinate system. The least squares method based on singular value decomposition is used in this paper.
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Prediction Technology on the Source Location of Acoustic Emission Signal in Plate with Welding Line
Sung Jae Lee, Yun Shick Jung, Jung Suk Kim, Myung Chang Kang, Kyu Dong Jung
J. Korean Soc. Precis. Eng. 2004;21(8):57-64.
Published online August 1, 2004
This study deals with the prediction of defect location which can be occurred in structure. The existing methods was very difficult to be applied to predict it, because of complex numerical formula. The triangulation method proposed in this study can predict the source location easily with small amount of data. The arrival time of wave can be directly converted into the distance between sensors. For this purpose, the propagation velocity was measured by Rayleigh wave, and the propagation behavior was analyzed. The welded workpiece is adapted to investigate for the consideration of jointed part in structure, The propagation velocity of signal was measured in welded workpiece and the revised algorithm of source location was proposed.
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Development of 3D Burr Measurement Technique using Conoscopic Holography
Sang-Wook Park, Sung-Lim Ko
J. Korean Soc. Precis. Eng. 2004;21(8):65-72.
Published online August 1, 2004
For the burrs formed in machining are irregular and very sharp in shape, it is usually very difficult to measure burr accurately. It was proved that micro burr geometry can be measured imprecision by the Conoprobe sensor using conoscopic holography method. We developed 3D burr measurement system using this sensor. The system is composed of Conoprobe sensor, XY table, controller and 3D measurement program. Some measurements using the developed system are conducted for the burrs formed in micro drilling and piercing. Specific software for burr measurement includes several function, calculation of burr volume, average burr height. Burs formed on a curved surface were compensated and measured successfully using the basic surface compensation function.
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Path Design Method of Mobile Robot for Obstacle Avoidance Using Ceiling-mounted Camera System and Its Implementation
Anh Kim Tran, Kwang Ju Kim, Tan Lam Chung, Hak Kyeong Kim, Sang Bong Kim
J. Korean Soc. Precis. Eng. 2004;21(8):73-82.
Published online August 1, 2004
In this paper, implementation of obstacle avoidance of a nonholonomic mobile robot in unstructured environment is introduced. To avoid obstacles, first, a reference collision-free path for the MR is generated off-line using HJB-based optimal path planning method. A controller is designed using integrator backstepping method for tracking the generated reference path. To implement the designed controller, a control system are needed and composed of camera system and PIC-based controller. The workspace is observed by a ceiling-mounted USB camera as part of an un-calibrated camera system. Thus the positional information of the MR is updated frequently and the MR can get the useful inputs for its tracking controller. The whole control system is realized by integrating a computer with PIC-based microprocessor using wireless communication: the image processing control module and path planning module serve as high level computer control while the device control serves as low level PIC microprocessor control. The simulation and experimental results show the effectiveness of the designed control system.
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Inspection of Automotive Oil-Seals sing Artificial Neural Network and Vision System
Byoung-Gook Loh, Gi Dae Kim
J. Korean Soc. Precis. Eng. 2004;21(8):83-88.
Published online August 1, 2004
The Classification of defected oil-seals using a vision system with the artificial neural network is presented. The artificial neural network for classification consists of 27 input nodes, 10 hidden nodes, and one output node. The selection of the number of the input nodes is based on an observation that the difference among the defected, non-defected, and smeared oil-seals is greatly pronounced in the 26 step gray-scale level thresholding. The number of the hidden nodes is chosen as a result of a trade-off between accuracy and computing time. The back -propagation algorithm is used for teaching the network. The proposed network is capable of successfully classifying the defected from the smeared oil-seals which tend to be classified as the defected ones using the binary thresholding. It is envisaged that the proposed method improves the reliability and productivity of the automotive vision inspection system.
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Measurement of Tensile Properties of Copper Foil using Micro-ESPI Technique
Dong Iel Kim, Yong Hak Huh, Chang Doo Kee
J. Korean Soc. Precis. Eng. 2004;21(8):89-96.
Published online August 1, 2004
Micro-tensile testing system, consisting of a micro tensile loading system and micro-ESPI(Electronic Speckle Pattern Interferometry) system, has been developed for measurement of micro-tensile properties of thin micro-materials. Micro-tensile loading system had a load cell with the maximum capacity of 50N and micro actuator with resolution of 4.5㎚ in stroke. The system was used to apply a tensile load to the micro-sized specimen. During tensile loading, the micro-ESPI system acquired interferometric speckle patterns in the deformed specimen and measured the in-plane tensile strain. The ESPI system consisted of a CCD-camera with a lens and the window-based program developed for this experiment. Using this system, stress-strain curves for 4 kinds of electrolytic copper foil 18□m thick were obtained. From these curves, tensile properties, including the elastic modulus, yielding strength and tensile strength, were determined and also values of the plastic exponent and coefficient based on Ramberg-Osgood relationship were evaluated.
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A Study on the Prediction of Failure Stress for Table Liner under Fatigue Load
Dong Woo Lee, Won Sik Joo
J. Korean Soc. Precis. Eng. 2004;21(8):97-105.
Published online August 1, 2004
The vertical roller mill is the important machine grinding and mixing various crude materials in the manufacturing process of portland cement. Table liner is one of grinding elements of vertical roller mill and is subjected to the cyclic bending stress by rollers and the centrifugal force by rotation of table. It demands 4×10? cycle of life but has 4×10?~8×10? cycle. It fractures at the edge of grinding path of outside roller. The repair expense for it amounts to 30% of total maintenance of vertical roller mill. Therefore, this study shows the fracture mechanism of table liner of vertical roller mill using HDM and fatigue analysis.
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Design for Micro-stereolithography using Axiomatic Approach
Seung-Jae Lee, In Hwan Lee, Dong-Woo Cho
J. Korean Soc. Precis. Eng. 2004;21(8):106-111.
Published online August 1, 2004
Micro-stereolithography technology has made it possible to fabricate any form of three-dimensional microstructures.
It makes a 3D structure by dividing the shape into many slices of relevant thickness along horizontal surface, hardening each layer of slice with a laser, and stacking them up to a desired shape. Until now, however, the micro-stereolithography device was not designed systematically because the key factors governing the device were not considered. In this paper, we designed micro-stereolithography device using axiomatic approach. This paper contains an overview and an analysis of a new proposed system for development of micro-stereolithography device, and detailed descriptions of the activities in this system. The newly designed system offers reduced machine size by minimizing of optical components and decoupled design matrix.
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The Effects of the Mounted Method of Frame of a Large Truck on Handling Performance
Il Dong Moon, ChaeYoun Oh, Seok Hyung Oh
J. Korean Soc. Precis. Eng. 2004;21(8):112-119.
Published online August 1, 2004
This paper develops a computer model of a cab over type large truck for estimating the effects of the mounted method of frame on handling performance. The computer model considers two mounted methods of frame; flange mounted and web mounted. Frame is modeled by finite elements using MSC/NASTRAN in order to consider the flexibility of frame. The reliability of the developed computer model is verified by comparing the actual vehicle test results with the simulation results. The actual vehicle test is performed in a double lane change course, and lateral acceleration, yaw rate, and roll angle are measured. To estimate the effects of the mounted method of frame on handling performance, simulations are performed with the flange mounted and web mounted frame. Simulation results show that the web mounted frame's variations of roll angle, lateral acceleration, and yaw rate are larger than the flange mounted frame's variations, especially in the high test velocity and the second part of the double lane course. Also, simulation results show that the web mounted frame's tendencies of roll angle, lateral acceleration, and yaw rate advance the flange mounted frame's tendencies, especially in the high test velocity and the second part of the double lane course.
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