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Constitutive Modeling of Magnesium Alloy Sheets

AIP Conference Proceedings 2007年第1期908卷 667-672页

作者： M. G. Lee K. Piao R. H. Wagoner J. K. Lee K. Chung H. Y. Kim 1Department of Materials Science and Engineering 2041 College Road Ohio State University Columbus OH 43210 2Department of Mechanical Engineering Scott Laboratory 201 West 19 Avenue Ohio State University Columbus OH 43210 3School of Materials Science and Engineering Intelligent Textile System Research Center Seoul National University 56‐1 Shinlim‐Dong Kwanak‐Ku Seoul 151‐742 Korea 4Division of Mechanical Engineering & Mechatronics Kangwon National University 192‐1 Hyoja 2‐Dong Chunchon Gangwon‐Do 200‐701 Korea

Magnesium alloy sheets have unique mechanical properties: high in‐plane anisotropy/asymmetry of yield stress and hardening response, which have not been thoroughly studied. The unusual mechanical behavior of magnesium alloys has been understood by the limited symmetry crystal structure of h.c.p metals and thus by deformation twinning. In this paper, the phenomenological continuum plasticity models considering the unusual plastic behavior of magnesium alloy sheet were developed for a finite element analysis. A new hardening law based on two‐surface model was developed to consider the general stress‐strain response of metal sheets such as Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. In terms of the anisotropy and asymmetry of the initial yield stress, the Drucker‐Prager’s pressure dependent yield surface was modified to include the anisotropy of magnesium alloys. Also, characterization procedures of material parameters for the constitutive equations were presented and finally the correlation of simulation with measurements was performed to validate the proposed theory.

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Forced Outage Cause Identification Based on Bayesian Networks

Forced Outage Cause Identification Based on Bayesian Network...

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Power Tech Conference

作者： A.B. Tronchoni C.O. Pretto V. Licks M.A. Rosa F.A.B. Lemos Electrical Energy System Group (GSEE) Pontifical Catholic University of Rio Grande do Sul Porto Alegre Rio Grande do Sul Brazil Mechanical and Mechatronics Engineering Department Pontifical Catholic University of RS Brazil INESC Porto Instituto de Engenharia de Sistema e Computadores do Porto Pontificia Universidade Católica do Rio Grande do Sul Rio Grande do Sul Brazil

The advances in area of information technology and applications, specially mobile and wireless technology, are providing conditions to improve data acquisition to be used in power system analysis. These conditions together with computational intelligence methods help provide an improvement in reliability analysis of distribution systems. This paper presents the development of a computational systems using mobile computing and a methodology based on Bayesian Networks to identify forced outage causes. The proposed system was validated using data collection of Brazilian distribution utility.

关键词： Bayesian methods Power system analysis computing Computer networks Mobile computing Personal digital assistants IEEE members Power system reliability Resource management Information technology Data acquisition

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The weldability of primer-coated steel for shipbuilding PI by CO 2 laser

The weldability of primer-coated steel for shipbuilding PI b...

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作者： Kim, Jong-Do Oh, Jin-Seok Park, Hyun-Joon Division of Marine System Engineering Korea Maritime University Dongsam-dong 1 Yeongdo-gu Busan 606-791 Korea Republic of Division of Mechatronics Engineering Korea Maritime University Korea Republic of Graduate School Korea Maritime University Korea Republic of

The application of laser welding technology has been considered to shipbuilding structure. However, when this technology is applied to primer-coated steel, good quality weld beads are not easily obtained. Because the primer-coated layer caused the spatter, humping bead and porosity which are main part of the welding defect attributed to the powerful vaporizing pressure of zinc. So we performed experiment with objectives of understanding spatter and porosity formation mechanism and producing sound weld beads in 6mm' primer coated steels by a CO2 CW laser. The effects of welding parameters;defocused distance, welding speed, coated thickness and coated position;were investigated in the bead shape and penetration depth on bead and lap welding. Alternative idea was suggested to suspend the welding defect by giving a reasonable gap clearance for primer coated thickness. The zinc of primer has a boiling point that is lower than melting point of steel. Zinc vapor builds up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Significant effects of primer coated position were lap side rather than surface. Therefore introducing a small gap clearance in the lap position, the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, formation and suspension mechanism of the welding defects was suggested by controlling the factors.

关键词： Steel

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Proposal of Distributed Architecture for Micromirror Image Generation in Maskless Optolithography system

Proposal of Distributed Architecture for Micromirror Image G...

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SICE Annual Conference

作者： Jaeman Choi Younghun Jin Haeryung Kim Manseung Seo Institute of Advanced Mechatronics for Thinfilm Engineering Needs Busan South Korea Department of Robot System Engineering Tongmyong University Busan South Korea Department of Mechatronics Engineering Tongmyong University Busan South Korea

Recent maskless lithography technologies using MEMS devices provide the attractive advantage of low cost manufacturing such as one for semiconductors. However, in order to utilize maskless lithography technology into large flat panel display manufacturing, the difficulties that arise in the generation and transmission of huge micromirror image data should be overcome. We aim to develop a strategy for real time data generation and transmission by distributing the huge image data being individually processed on multiple computers. Entire image data generation processes relevant to maskless lithography are analyzed upon the unit micromirror. As a result, the distributed architecture capable of image data generation and transmission is devised. Communications and controls between the distributed systems are performed upon the client-sever model. For the verification of the proposed architecture, lithography experiments fabricating actual patterns on wafers are carried out with a set of two image data individually generated on two different computers upon the distributed architecture. The boundary created by two interfacing micromirrors is matched exactly. The accuracy of the system upon the proposed architecture is ensured through the actual FPD fabrication

关键词： Proposals Micromirrors Image generation Lithography Computer architecture Semiconductor device manufacture Distributed computing Microelectromechanical devices Costs Flat panel displays

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Micromirror based Lithography Simulation system based on Overlay Intensity Basis

Micromirror based Lithography Simulation System based on Ove...

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SICE Annual Conference

作者： Kiwon Park Jaeman Choi Haeryung Kim Manseung Seo Institute of Advanced Mechatronics for Thinfilm Engineering Needs Busan South Korea Department of Mechatronics Engineering Tongmyong University Busan South Korea Department of Robot System Engineering Tongmyong University Busan South Korea

To generate proper patterns for micromirror based lithography, millions of micromirrors need to be addressed and adjusted, individually and instantaneously. In this study, a strategy for micromirror based lithography simulation is proposed. Accounting for the instantaneous distribution of the light energy from a rotated micromirror onto a translating substrate, the overlay intensity basis is defined as the three-dimensional pattern image upon the accumulation of irradiated energy by a unit micromirror per unit translating phase. A prototype lithography simulation system for generating lithographic data and predicting the lithography results is implemented upon the overlay intensity basis. To ensure the system works, parallel with the simulation, actual lithography is performed on prototype equipment to fabricate actual wafers. The overall results of the simulations and experiments show consistency, both physically and mathematically. The properness of the proposed strategy for micromirror based lithography simulation and the precision of the implemented lithography simulation system are ensured

关键词： Micromirrors Lithography Virtual prototyping Fabrication Optical reflection Substrates Circuit simulation mechatronics Predictive models Digital control

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Lithographic Data Generation Algorithm based on Micromirror Cell Decomposition

Lithographic Data Generation Algorithm based on Micromirror ...

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SICE Annual Conference

作者： Younghun Jin Kiwon Park Haeryung Kim Manseung Seo Department of Robot System Engineering Tongmyong University Busan South Korea Institute of Advanced Mechatronics for Thinfilm Engineering Needs Busan South Korea Department of Mechatronics Engineering Tongmyong University Busan South Korea

In maskless lithography, micromirrors in an array work like a mask to write patterns directly onto substrates. We focus our attention on lithographic data generation for digital micromirror device (DMD) based maskless lithography on a huge substrate, with no manipulation of the light source shape, with no adjustment of mirror tilting angles, and/or without grey imaging levels. To overcome the limitations of existing lithographic data generation methods developed upon the assessment of lithographic paths of the reflected beam spots, we place our primary concern on the pattern. To generate lithographic data for controlling the on/off reflection of millions of micromirrors, we devise a unique criterion, the occupancy limit. By comparing the actual occupancy of the pattern per unit micromirror to the occupancy limit, which is a value determined upon the lithography process condition by the user, binary reflections off micromirrors are approved. A strategy for the computation of the actual occupancy of the pattern per unit micromirror is devised upon the micromirror cell decomposition (MCD). The MCD algorithm for lithographic data generation is proposed. For verification, along with a lithography simulation, an actual lithography experiment is performed to fabricate a pattern on a wafer

关键词： Micromirrors Lithography Substrates Mirrors Shape Optical reflection Fabrication Data engineering Electronic mail Light sources

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Design of Ambulatory ECG Monitoring system to detect ST pattern change

Design of Ambulatory ECG Monitoring System to detect ST patt...

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SICE Annual Conference

作者： Gu-young Jeong Kee-ho Yu Division of Mechatronics Engineering Chonbuk National University of Korea Jeonju South Korea Division of Mechanical and AeroSpace System Engineering Chonbuk National University of Korea Jeonju South Korea

In this paper, we describe the hardware configuration for the ambulatory ECG monitoring device and the algorithm for detection of ST pattern change. The ambulatory ECG recording are available for diagnosis of the heart diseases such as myocardial infarction, arrhythmia, etc. It especially is important to detect the transient ECG pattern change caused by the unbalance between the oxygen supply and the oxygen demand in the cardiac muscle that is called myocardial ischemia. This is one of the reasons why the ambulatory ECG monitoring system is necessary. We designed the portable ECG measurement device with the analysis algorithm. The algorithm analyzes the ECG signal and detects the transient ST changes. The detection of QRS complex is accomplished using its the morphological characteristics such as the steep slope and high amplitude. The developed algorithm detects the ST level change, and then classify the ST shape type using the polynomial approximation. The algorithm finds the least squares curve for the data between S wave and T wave in ECG. This curve is used for the classification of the ST shapes. ST type is classified by calculating the difference between the reference ST type and the least square curve. Through the result from the developed algorithm, we can know when the ST level change occurs and what the ST shape type is. The portable ECG device consists of instrumentation amplifier, multiplexer, micro-controller, filter and transmitter module. The designed ECG device measures ECG with four electrodes on the body and transmits the measured ECG signal to the receiver connected in PC by digital radio way. The available range of wireless communication is 70 m in building and 300 m in open ground

关键词： Electrocardiography Monitoring Change detection algorithms Algorithm design and analysis Shape Myocardium Least squares methods Hardware Cardiac disease Muscles

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Measuring the Electronic Properties of Poly-Si Thin Film Solar Cells Deposited on Textured Substrate

Measuring the Electronic Properties of Poly-Si Thin Film Sol...

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International Conference on Properties and Applications of Properties and Applications of Dielectric Materials

作者： R. Muhida Age Sutjipto T. Matsui T. Toyama H. Okamoto Department of Mechatronics Engineering Department of Manufacturing and Materials Engineering International Islamic University Malaysia Jalan Gombak Kuala Lumpur Malaysia Department of System Innovation Osaka University Toyonaka Osaka Japan

Electrical properties of PECVD produced poly-Si photovoltaic layers on the various textured substrates showing the light trapping effect have been investigated using an AC-conductivity technique. From temperature dependence of electron (hole) conductivities using n-i-n (p-i-p) structures, the Fermi level of the poly-Si layer on the slightly textured substrates is found to locate at the center of the band gap and this material is 'truly' intrinsic. As RMS roughness of the textured substrate, sigma increases, the Fermi level becomes close to conduction band edge, and finally, the poly-Si layer on the highly textured substrate exhibits n-type character even though any deposition conditions for the poly-Si layers are not changed at all. Changes in electrical conductivities of the poly-Si thin films in conjunction with the results on photovoltaic performances and microstructure are also discussed

关键词： Sputtering Photovoltaic cells Substrates Photovoltaic systems Solar power generation Conductivity Electron traps Temperature dependence Charge carrier processes Photonic band gap

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Contamination Control Strategy based on Particle Flow Behavior near Fast Moving Devices in Flat Panel Display Fabrication Cleanroom

Contamination Control Strategy based on Particle Flow Behavi...

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SICE Annual Conference

作者： Hyunsik Chio Hyuntae Cho Giljun Kim Haeryung Kim Manseung Seo Department of Robot System Engineering Tongmyong University Busan South Korea LG PERI LG Electronics Kyunggi South Korea Department of Mechatronics Engineering Tongmyong University Busan South Korea

In flat panel display (FPD) fields, the defect rate of the final products yields the rate of particle deposition on FPD panels. Every best endeavor has been made to maintain a clean fabrication environment. However, contamination by airborne particles is still significant. Moreover, contamination by particles near fast moving devices such as a lift or loader has been reported as being serious. Existing well-known treatments for contamination control never worked near fast moving devices. Thus, at this stage, devising a new contamination control strategy based on the analysis of particle flow behavior upon device movement is inevitable to increase FPD productivity. In this study, the particle flow behavior near a fast moving lift is analyzed based upon the results of two and three dimensional transient flow simulations. The simulation results show consistency, insisting that the proposed approach is proper and reliable. Based on our experience associated with FPD cleanrooms and equipment, a new contamination control strategy for the moving lift system in a FPD cleanroom is proposed

关键词： Contamination Flat panel displays Fabrication Manufacturing Control systems Liquid crystal displays Plasma displays Glass Productivity Protection

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Development of Tracking Buoy system having Auto Tilting Compensation Mechanism

Development of Tracking Buoy System having Auto Tilting Comp...

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SICE Annual Conference

作者： Myung-jin Chung Byoung-kyu Park Jong-su Park Young-jung Kim Department of Mechatronics Engineering Korea Polytechnic University Siheung South Korea Department of Hardware Research and Development KMI System Company Limited Sungnam South Korea Department of Mechanical System Research and Development Ocean Engineering Company Limited Kangju South Korea

The tracking buoy system is used to monitoring the weather or ocean status by transmission of the data about the weather and ocean status according to buoy position via code division multiple access (CDMA) communication. CDMA antenna is used to enlarge the distance of the data transmission. By the deviation of the antenna from the vertical position by wind or waves, quality of the transmitting data is deteriorated. So antenna tilting compensation mechanism is required to the tracking buoy used in the ocean. In this work, tracking buoy system having auto tilting compensation mechanism is developed. Auto tilting compensation is achieved by ballast weight positioned at the center under the buoy hull. From the performance test, moving angle of the buoy hull without tilting of the CDMA antenna is plusmn65deg. The data loss during the CDMA communication does not measured in the condition of plusmn80deg tilting of buoy hull

关键词： Multiaccess communication Oceans Transmitting antennas Monitoring Underwater communication Data communication Wind Electronic ballasts Testing Antenna measurements

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