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Volume 26(11); November 2009

Articles
Eyesight and Hearing Assistant Technique using Multiple Sensory Display
Yon-Kyu Park, In-Mook Choi, Whee-Kuk Kim, Dae-Im Kang
J. Korean Soc. Precis. Eng. 2009;26(11):7-11.
Published online November 1, 2009
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A Bio-mimetic Technology for the Light Sense
Doo-Seung Um, Sang-Hyeob Kim, Myung-Ae Chung, Chang-Il Kim
J. Korean Soc. Precis. Eng. 2009;26(11):12-19.
Published online November 1, 2009
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Recent Trends in MEMS Microphone and Application for Hearing Aid System
Shin Hur, Hongsoo Choi, Joonsik Park, Yang-Han Kim
J. Korean Soc. Precis. Eng. 2009;26(11):20-28.
Published online November 1, 2009
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Bio-mimic Electronic Artificial Skin based on Flexible Electronics
Min Seok Kim, Jong Ho Kim, Han Wook Song, Yon Kyu Park
J. Korean Soc. Precis. Eng. 2009;26(11):29-34.
Published online November 1, 2009
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Tool Locus Analysis of Ultra-precision Inclined Grinding
Yeon Hwang, Soon Sub Park, Ki Yong Lee, Jong Ho Won, Hyun Ho Kim
J. Korean Soc. Precis. Eng. 2009;26(11):35-40.
Published online November 1, 2009
This paper presents the geometrical analysis of an inclined ultra-precision grinding technology using simulations about grinding point locus for micro lens manufacturing. Simulation results show the relationship between radius ratios(R₁/R₂) and wheel center locus. Furthermore, the critical grinding wheel radius(R₁) can be calculated from work-piece radius(R₂) and inclined angle(θ=-45°). These achievements could be applied to calculate CNC data in ultra-precision grinding and give insight for wheel wear and compensation grinding.
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Measurement of the Time Constant of Industrial Platinum Resistance Thermometers
Yong-Gyoo Kim, Sook Hyang Kim, Inseok Yang
J. Korean Soc. Precis. Eng. 2009;26(11):41-46.
Published online November 1, 2009
We present experimental data on the time response behavior of industrial platinum resistance thermometers (IPRT) to help with the selection of proper sensors in industry and research laboratories. Time constants of IPRTs were measured using a method specified in ASTM standards. Two different sensors of different protecting sheath diameters were tested in air, water and silicon oil at temperatures from 0 °C to 200 °C. The time constant was the smallest in water and the highest in air. As the test temperature increased, time constants tended to decrease at all heat conducting media. For different diameters of sheath of IPRT at the same temperature, it was found that the IPRT of larger diameter showed higher time constant in air, but the opposite dependence was observed in water and oil. From the measured results, it was suggested that the sensor diameter and heat conducting medium should be considered if one wants to select proper thermometer to measure the dynamic temperature change in industry and research area.
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Fault Detection System Development for a Spin Coater Through Vibration Assessment
Jun Hee Moon, Bong Gu Lee
J. Korean Soc. Precis. Eng. 2009;26(11):47-54.
Published online November 1, 2009
Spin coaters are the essential instruments in micro-fabrication processes, which apply uniform thin films to flat substrates. In this research, a spin coater diagnosis system is developed to detect the abnormal operation of TFT-LCD process in real time. To facilitate the real-time data acquisition and analysis, the circular-buffered continuous data transfer and the short-time Fourier transform are applied to the fault diagnosis system. To determine whether the system condition is normal or not, a steady-state detection algorithm and a frequency spectrum comparison algorithm using confidence interval are newly devised. Since abnormal condition of a spin coater is rarely encountered, algorithm is tested on a CD-ROM drive and the developed program is verified by a function generator. Actual threshold values for the fault detection are tuned in a spin coater in process.
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Defect Detection of Wall Thinned Straight Pipe using Shearography and Lock-in Infrared Thermography
Kyeong Suk Kim, Hyun Chul Jung, Ho Seob Chang, Ha Sig Kim, Sung Won La
J. Korean Soc. Precis. Eng. 2009;26(11):55-61.
Published online November 1, 2009
The wall thinning defect of nuclear power pipe is mainly occurred by the affect of the flow accelerated corrosion (FAC) of fluid. This type of defect becomes the cause of damage or destruction of in carbon steel pipes. Therefore, it is very important to measure defect which is existed not only on the welding part but also on the whole field of pipe. This study use dual-beam Shearography, which can measure the out-of-plane deformation and the in-plane deformation by using another illuminated laser beam and simple image processing technique. And this study proposes Infrared thermography, which is a two-dimensional non-contact nondestructive evaluation that can detect internal defects from the thermal distribution by the inspection of infrared light radiated from the object surface. In this paper, defect of nuclear power pipe were, measured using dual-beam shearography and infrared thermography, quantitatively evaluated by the analysis of phase map and thermal image pattern.
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Development of an Equilibrium Sensation Measuring System for Human Being
Gab Soon Kim
J. Korean Soc. Precis. Eng. 2009;26(11):62-69.
Published online November 1, 2009
This paper describes the development of the new type equilibrium sensation measuring system for human with handicap in the equilibrium sensation. The medium and small hospital could not use the developed equilibrium sensation measuring system, because it is very high prices. Therefore, the new type system should be developed to measure the numerical value of the equilibrium sensation in human with handicap. In this paper, First, two 3-axis force/moment sensors which can measure force Fz, moments Mx and My simultaneous were designed and manufactured, second, the high speed measuring device which can acquire the output from two 3-axis force/moment sensors, third, the new type equilibrium sensation measuring system was developed, then the characteristic test of the developed equilibrium sensation measuring system carried out, it is confirmed that the system could measure the swing body of human with handicap.
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Modeling and Identification of Web Tension Control System with Dancer Roll
Sang Hwa Lee, Jeh Won Lee, Hyuk Jin Lee
J. Korean Soc. Precis. Eng. 2009;26(11):70-76.
Published online November 1, 2009
Web tension control system recently have been applied to OLED(Organic Light-Emitting Diode), RFID of flexible material, e-Paper and PLED(Polymeric LED) and various web control algorithms have being developed for higher productivity and product quality. These system need an accuracy model to design and implement controller. In this paper, the web tension control system with dancer roll is mathematically modeled. Mathematical model consists of 8 subsystems and each subsystems can be described as impedance structure which connected by velocity and tension. Mathematical model is different from the estimated model at high frequency range because of structure dynamics which is ignored on mathematical model. The estimated model is derived using ARMAX model. The controller is designed using the estimated model. The step response of the estimated model are compared with that of physical model for a validation of estimated model. The experimental results show a good match between them.
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Development of Panel Alignment Algorithm and Its Application to BGA Lithography Equipment
Sun Joong Ryu
J. Korean Soc. Precis. Eng. 2009;26(11):77-84.
Published online November 1, 2009
Alignment error of the BGA lithography equipment is mainly caused by the dimensional change of the BGA panel which is generated during the manufacturing processes. To minimize the alignment error, ‘mark alignment’ algorithm in place of ‘center alignment’ algorithm was proposed and the optimal solution for the algorithm was derived by simple analytic form. The developed algorithm distributes evenly the alignment error over the whole panel which was evaluated by the numerical simulation. Finally, the developed algorithm was implemented to the controller of the lithography equipment and the alignment error was measured at the fiducial mark location. From the measurement, it is also concluded that the developed alignment algorithm be effective to reduce the maximum value of alignment error.
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A Study on the Relationship between Stress Relaxation and Performance of a Lip Seal
Myung-Ho Yoo, Taek-Sung Lee
J. Korean Soc. Precis. Eng. 2009;26(11):85-91.
Published online November 1, 2009
A lip seal is widely used not only to prevent leakage of fluids from an actuator or a rotating shaft but also to exclude outside substances. Recently, TPU(Thermoplastic Polyurethane), which is one of the sealing materials, has been frequently used due to its excellent mechanical properties and wear resistance. The material constants for finite element analysis through the experiment on stress relaxation are presented. The reaction forces of a shaft as well as the contact pressures of a lip seal under condition before and after stress relaxation using finite element analysis were obtained, The results show that stress relaxation has not a little effect on the performance of a lip seal.
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Design and Analysis of an Objective Lens for a Scanning Electron Microscope by Coupling FE Analysis and Ray Tracing
Keun Park, Jae-Jin Lee, Man-Jin Park, Dong-Hwan Kim, Dong-Young Jang
J. Korean Soc. Precis. Eng. 2009;26(11):92-98.
Published online November 1, 2009
The scanning electron microscope (SEM) contains an electron optical system in which electrons are emitted and moved to form a focused beam, and generates secondary electrons from the specimen surfaces, eventually making an image. The electron optical system usually contains two condenser lenses and an objective lens. The condenser lenses generate a magnetic field that forces the electron beams to form crossovers at desired locations. The objective lens then focuses the electron beams on the specimen. The present study covers the design and analysis of an objective lens for a thermionic SEM. A finite element (FE) analysis for the objective lens is performed to analyze its magnetic characteristics for various lens designs. Relevant beam trajectories are also investigated by tracing the ray path of the electron beams under the magnetic fields inside the objective lens.
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Optimum Bar-feeder Support Positions of a Miniature High Speed Spindle System by Genetic Algorithm
Jae-Hoon Lee, Musu Kim, Seonghun Park, Jae-Keun Kang, Shibok Lee
J. Korean Soc. Precis. Eng. 2009;26(11):99-107.
Published online November 1, 2009
Since a long work piece influences the natural frequency of the entire system with a miniature high speed spindle, a bar-feeder is used for a long work piece to improve the vibration characteristics of a spindle system. Therefore, it is very important to design optimally support positions between a bar-feeder and a long work piece for a miniature high speed spindle system. The goal of the current paper is to present an optimization method for the design of support positions between a bar-feeder and a long work piece. This optimization method is effectively composed of the method of design of experiment (DOE), the artificial neural network (ANN) and the genetic algorithm (GA). First, finite element models which include a high speed spindle, a long work piece and the support conditions of a bar-feeder were generated from the orthogonal array of the DOE method, and then the results of natural vibration analysis using FEM were provided for the learning inputs of the neural network. Finally, the design of bar-feeder support positions was optimized by the genetic algorithm method using the neural network approximations.
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An Effective Design Method of Stamping Process by Feasible Formability Diagram
Seung-Hoon Cha, Chan-Joo Lee, Sang-Kon Lee, Bong-Hwan Kim, Dae-Cheol Ko, Byung-Min Kim
J. Korean Soc. Precis. Eng. 2009;26(11):108-115.
Published online November 1, 2009
In metal forming technologies, the stamping process is one of the significant manufacturing processes to produce sheet metal components. It is important to design stamping process which can produce sound products without defect such as fracture and wrinkle. The objective of this study is to propose the feasible formability diagram which denotes the safe region without fracture and wrinkle for effective design of stamping process. To determine the feasible formability diagram, FE-analyses were firstly performed for the combinations of process parameters and then the characteristic values for fracture and wrinkle were estimated from the results of FEanalyses based on forming limit diagram. The characteristic values were extended through training of the artificial neural network. The feasible formability diagram was finally determined for various combinations of process parameters. The stamping process of turret suspension to support suspension module was taken as an example to verify the effectiveness of feasible formability diagram. The results of FE-analyses for process conditions within fracture and wrinkle as well as safe regions were in good agreement with experimental ones.
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