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Volume 22(9); September 2005

Articles
Effective Deburring of Micro Burr using Magnetic Abrasive Finishing
Jung Il Park, Sung Lim Ko, Yuri M. baron
J. Korean Soc. Precis. Eng. 2005;22(9):7-13.
Published online September 1, 2005
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Deburring Technology Using Ultrasonic Cavitation
Hon Zong Choi, Seok Woo Lee, Young Jae Choi, Sung Lim Ko
J. Korean Soc. Precis. Eng. 2005;22(9):14-19.
Published online September 1, 2005
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Removal of micro burr by using Electrolytic-deburring
Eun-Sang Lee, Jung-Hoon Lee, Won-Mook Kim, Young-Jae Chun
J. Korean Soc. Precis. Eng. 2005;22(9):20-26.
Published online September 1, 2005
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A Study on the Truing of Diamond Wheel for Micro V-shaped Groove Grinding
Joo Sang Lee
J. Korean Soc. Precis. Eng. 2005;22(9):27-33.
Published online September 1, 2005
This study deals with the truing of diamond wheel for the manufacture of micro v-shaped grooves with fine sharp edges in the grinding. Fine micro v-shaped grooves are key components to fabricate LGP(light guide plate), optical fiber connector and so on. Conventional v-shaped groove methods such as etching and lithography are difficult to make grooves with accuracy and cutting by lathe is difficult to select target materials. Therefore, as a preliminary stage to developing the grinding technology that will be expected fabrications for micro 3-dimensional structure of high effectivity and accuracy and freed up the restrictions of machinability to the materials for micro v-shaped grooves, truing is carried out with resin bond diamond wheel and electro forming diamond wheel using a cup-type truer. From the experimental results, it is found that the effects according to working direction of the cup-type truer and the restrainable methods of plastic deformation that is generated at wheel edge are examined. As a result, fine micro v-shaped diamond wheel was obtained, which are applicable to micro grinding for optical devices.
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Study on the laser transmission-welding of thermoplastics
Myung-hee Seo, Kwang-hyun Ryu, Gi-jung Nam
J. Korean Soc. Precis. Eng. 2005;22(9):34-40.
Published online September 1, 2005
Laser welding of thermoplastics is a new jointing technique with a host of advantages. It is not only another extremely useful welding method but also a cost-effective alternative to traditional techniques involving screws or adhesives. Transmission laser-welding of thermoplastics such as polycarbonate(PC), polypropylene(PP), polyvinyl chloride(PVC), low density polyethylene(LDPE) and acrylic using a high power diode laser has been studied experimentally. The optical transmission of each plastic has been measured at laser wavelength of 808nm. The weld process has been characterized by the specific energy and weld time required for each plastic. The characteristics of laser welding between same plastics have also been analyzed.
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Development of Technique to Improve the Formability of the Rear Floor in Series Stamping Process
Dong Hwan Kim, Jung Min Lee, Young Ho Go, Hae Gue Cha, Byung Min Kim
J. Korean Soc. Precis. Eng. 2005;22(9):41-48.
Published online September 1, 2005
In this study, to improve the formability of the rear floor in series stamping process, the method for predicting the temperature of tools and steel sheet is proposed using FE analysis. To do this, tensile tests and straight pulling friction tests of three steel sheets are carried out at temperatures up to 300℃, and the effect of temperature on the tensile properties and the characteristics of friction are examined. The steel sheets have a higher n-value in the temperature range of about 50℃ and it is related to the maximum uniform elongation. Also, the blue shortness occurs in the temperature range of about 150℃. When the temperature is higher than 200℃, the friction coefficient increase with increasing temperature. From the FE-simulation, the effects of the punch temperature considering heat expansion in the number of stamping are examined and discussed. The technique developed in this study for estimating tool temperature can be used to develop more feasible ways to improve continuous productivity in series stamping process.
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FE analysis of Extrusion Process and Estimation of Welding strength for micro Multi Cell Tube with Serration
Jung Min Lee, Byung Min Kim, Hyung Ho Jo, Chung Gil Kang
J. Korean Soc. Precis. Eng. 2005;22(9):49-59.
Published online September 1, 2005
This paper describes a development of the extrusion process and estimation of the weldability for multi cell tubes used to cooling system of automobiles. A study on extrusion process is performed through the 3D FE simulation in non-steady state and extrusion experimentation. Also, nano-indentation test is employed to estimate the weldability of tubes. Especially, An evaluation of the weldability using the nano-indentation is accomplished as compared with nano-hardness in welded part and in the others. Finally, the pattern of the mandrel defection is investigated according to shapes of the porthole and/or chamber.
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Modeling of Polymer Ablation with Excimer Lasers
Kyung Koo Yoon, Se Yoon Bang
J. Korean Soc. Precis. Eng. 2005;22(9):60-68.
Published online September 1, 2005
To investigate the effects of beam focusing in the etching of polymers with short pulse Excimer lasers, a polymer etching model of SSB's is combined with a beam focusing model. Through the numerical simulation, it was found that in the high laser fluence region, SSB model considering both photochemical and thermal contribution is considered to be suitable to predict the etched hole shape than a simple photochemical etching model. The average temperature distribution into the substance obtained by assuming 1-D heat transfer is found to be fairly similar to the fluence distribution on the ablated surface. The experimental etching data for polymers are used to give material properties for ablation model. The fitted etch depth curve gives a nice agreement with the experimental data.
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Compensation of the Straightness Measurement Error in the Laser Interferometer
Gyungho Khim, Tae-Ho Keem, Husang Lee, Seung-Woo Kim
J. Korean Soc. Precis. Eng. 2005;22(9):69-76.
Published online September 1, 2005
The laser interferometer system such as HP5529A is one of the most powerful equipment for measurement of the straightness error in precision stages. The straightness measurement system, HP5529A is composed of a Wollaston prism and a reflector. In this system, the straightness error is defined as relative lateral motion change between the prism and the reflector and computed from optical path difference of two polarized laser beams between these optics. However, rotating motion of the prism or the reflector used as a moving optic causes unwanted straightness error.
In this paper, a compensation method is proposed for removing the unwanted straightness error generated by rotating the moving optic and an experiment is carried out for theoretical verification. The result shows that the unwanted straightness error becomes very large when the reflector is used as the moving optic and the distance between the reflector and the prism is far. Therefore, the prism must be generally used as the moving optic instead of the reflector so as to reduce the measurement error. Nevertheless, the measurement error must be compensated because it's not a negligible error if a rotating angle of the prism is large. In case the reflector must be used as the moving optic, which is unavoidable when the squareness error is measured between two axes, this compensation method can be applied and produces a better result.
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Robust 3D visual tracking for moving object using pan-tilt stereo cameras
Che Seung Cho, Byeong Mook Chung, In Su Choi, Sang Hyun Nho, Yoon Kyu Lim
J. Korean Soc. Precis. Eng. 2005;22(9):77-84.
Published online September 1, 2005
In most vision applications, we are frequently confronted with determining the position of object continuously. Generally, intertwined processes are needed for target tracking, composed with tracking and control process. Each of these processes can be studied independently. In case of actual implementation we must consider the interaction between them to achieve robust performance. In this paper, the robust real time visual tracking in complex background is considered. A common approach to increase robustness of a tracking system is to use known geometric models (CAD model etc.) or to attach the marker. In case an object has arbitrary shape or it is difficult to attach the marker to object, we present a method to track the target easily as we set up the color and shape for a part of object previously. Robust detection can be achieved by integrating voting-based visual cues. Kalman filter is used to estimate the motion of moving object in 3D space, and this algorithm is tested in a pan/tilt robot system. Experimental results show that fusion of cues and motion estimation in a tracking system has a robust performance.
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Recognition method of small-obstacles using a camera for a mobile robot
Gab-Soon Kim
J. Korean Soc. Precis. Eng. 2005;22(9):85-92.
Published online September 1, 2005
This paper describes the recognition method of small-obstacles using a camera for a mobile robot in indoor environment. The technique of image processing using a camera has been widely used for an automaton of industrial system, an inspection of inferior goods, a lookout of an invader, and a vision sensor of intelligent robot. Mobile robot could meet small-obstacles such as a small plastic bottle of about 0.5 l in quantity, a small box of 7×7×7 ㎤ in volume, and so on in its designated path, and could be disturbed by them in the locomotion of a mobile robot. So, it is necessary to research on the recognition of small-obstacles using a camera and program. In this paper, 2-D image processing algorism and method for recognition of small-obstacles using a camera for a mobile robot in indoor environment was developed. The characteristic test of the developed program to confirm the recognition of small-obstacles was performed. It is shown that the developed program could judge the size and the position of small-obstacles accurately.
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Study of Design Characteristics of Flexible Manufacturing System for Practical Training
Janghyen Jo
J. Korean Soc. Precis. Eng. 2005;22(9):93-98.
Published online September 1, 2005
The purposes of this paper are the review and derivation of design characteristics for the new construction of the practical flexible manufacturing system. The basic ideas to analyze the manufacturing system which is the automatically operated are dependant on the various manufacturing procedures in factory. The practical flexible manufacturing systems have various mechanical subsystems appropriated for the final manufacturing products. Therefore the systems have the various kinds of hardwares as well as softwares. We study the software for the practical flexible manufacturing system designed and developed in the Halla University with the related company. Specially the design concepts and using specifications of all subsystems which are composed of mechanical and electronic movements of the product are analyzed and introduced in this dissertation.
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Implementation of Visual Data Compressor for Vision Sensor of Mobile Robot
Hyung O Kim, Kyoung Su Cho, Moon Yeal Baek, Chang Doo Kee
J. Korean Soc. Precis. Eng. 2005;22(9):99-106.
Published online September 1, 2005
In recent years, vision sensors are widely used to mobile robot for navigation or exploration. The analog signal transmission of visual data being used in this area, however, has some disadvantages including noise weakness in view of the data storage. A large amount of data also makes it difficult to use this method for a mobile robot.
In this paper, a digital data compressing technology based on MPEG4 which substitutes for analog technology is proposed to overcome the disadvantages by using DWT(Discreate Wavelet Transform) instead of DCT(Discreate Cosine Transform). The TI Company's DSP chip, TMS320C6711, is used for the image encoder, and the performance of the proposed method is evaluated by PSNR(Peake Signal to Noise Rates), QP(Quantization Parameter) and bitrate.
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PC Based Distributed Control System of AGV with Multi-Thread Method
Sung Jae Jun, Yon Sang Cho, Heung Sik Park
J. Korean Soc. Precis. Eng. 2005;22(9):107-114.
Published online September 1, 2005
With the recent progress in flexible manufacturing systems (FMS) in industry, increasing attention has been given to Automatic Guided Vehicle (AGV) systems. An AGV is a self-powered unit for transporting materials between stations without needing to be controlled by an operator. Such a system has several sensors to recognize the external state, and it is designed to travel between stations automatically without external assistance. To manage each device automatically in real time it requires a distributed controller with a main computer as the host, as well as a number of micro-controllers. In this study, an AGV system with dual motor drive was constructed. A Pentium 4 personal computer was set up as the main host for the distributed control, and this communicated with other micro-controllers in the management of the motor. The speed of each motor was also controlled by a micro-controller.
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A Measurement Method of Three-Dimensional Surface Morphology Based on Depth-from-Focus through Linear Magnification Calibration
Gyung Bum Kim, Young Su Shin
J. Korean Soc. Precis. Eng. 2005;22(9):115-122.
Published online September 1, 2005
Errors resulting from magnification variations of a optical system are largely generated in three-dimensional shape measurements based on depth-from-focus. In the case of measuring the surface morphology of tiny objects based on DFF, images are acquired with a very small interval so that magnification changes can be minimized. However, the magnification variations are actually existed in the acquired images and so focus measures are wrongly or ambiguously extracted. In this paper, a methodology with linear magnification calibrations, based on DFF, is proposed to make more accurate measurement in surface morphology with high depth discontinuity, compared with previous ones. Several experiments show that the proposed method outperforms existing ones without magnification calibrations.
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