• Title/Summary/Keyword: Anisotropic characteristic

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Computational aspects of guided wave based damage localization algorithms in flat anisotropic structures

  • Moll, Jochen;Torres-Arredondo, Miguel Angel;Fritzen, Claus-Peter
    • Smart Structures and Systems
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    • v.10 no.3
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    • pp.229-251
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    • 2012
  • Guided waves have shown a great potential for structural health monitoring (SHM) applications. In contrast to traditional non-destructive testing (NDT) methodologies, a key element of SHM approaches is the high process of automation. The monitoring system should decide autonomously whether the host structure is intact or not. A basic requirement for the realization of such a system is that the sensors are permanently installed on the host structure. Thus, baseline measurements become available that can be used for diagnostic purposes, i.e., damage detection, localization, etc. This paper contributes to guided wave-based inspection in anisotropic materials for SHM purposes. Therefore, computational strategies are described for both, the solution of the complex equations for wave propagation analysis in composite materials based on exact elasticity theory and the popular global matrix method, as well as the underlying equations of two active damage localization algorithms for anisotropic structures. The result of the global matrix method is an angular and frequency dependent wave velocity characteristic that is used subsequently in the localization procedures. Numerical simulations and experimental investigations through time-delay measurements are carried out in order to validate the proposed theoretical model. An exemplary case study including the calculation of dispersion curves and damage localization is conducted on an exemplary unidirectional composite structure where the ultrasonic signals processed in the localization step are simulated with the spectral element method. The proposed study demonstrates the capabilities of the proposed algorithms for accurate damage localization in anisotropic structures.

A Study on the Process Conditions of ACA( Anisotropic Conductance Adhesives) for COG ( Chip On Glass) (COG(Chip On Glass)를 위한 ACA (Anisotropic Conductive Adhesives) 공정 조건에 관한 연구)

  • Han, Jeong-In
    • Korean Journal of Materials Research
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    • v.5 no.8
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    • pp.929-935
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    • 1995
  • In order to develop COG (Chip On Glass) technology for LCD module interconnecting the driver IC to Al pad electrode on the glass substrate, Anisotropic Conductive Adhesive(ACA) process, the most promising one among COG technologies, was investigated. ACA process was carried out by two steps, dispensing of ACA resin in the bonding area and curing by W radiation. Load on the chip was ranged from 2.0 to 15kg and the chip was heated at about 12$0^{\circ}C$. In resin, the density of conductive particles coated with Au or Ni at the surface were 500, 1000, 2000 and 4000 particles/$\textrm{mm}^2$, and the diameter of particles were 5, 7 and 12${\mu}{\textrm}{m}$. As a result of the experiments, ACA process using ACA particle of diameter and density of 5${\mu}{\textrm}{m}$ and 4000 particles/$\textrm{mm}^2$ respectively shows optimum characteristic with the stabilzed bonding properties and contact resistance.

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Anisotropic Wet Etching of Single Crystal Silicon for Formation of Membrane Structure (멤브레인 구조 제작은 위한 단결정 실리콘의 이방성 습식 식각)

  • 조남인;강창민
    • Journal of the Semiconductor & Display Technology
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    • v.2 no.4
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    • pp.37-40
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    • 2003
  • We have studied micro-machining technologies to fabricate parts and sensors used in the semiconductor equipment. The studies were based on the silicon integrated circuit processes, and composed of the anisotropic etching of single crystal silicon to fabricate a membrane structure for hot and cold junctions in the infrared absorber. KOH and TMAH were used as etching solutions for the anisotropic wet etching for membrane structure formation. The etching characteristic was observed for the each solution, and etching rate was measured depending upon the temperature and concentration of the etching solution. The different characteristics were observed according to pattern directions and etchant concentration. The pattern was made to incline $45^{\circ}$ on the primary flat, and optimum etching property was obtained in the case of 30 wt% and $90^{\circ}C$ of KOH etching solution for the formation of the membrane structure.

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Micro Joining Process Using Solderable Anisotropic Conductive Adhesive (Solderable 이방성 도전성 접착제를 이용한 마이크로 접합 프로세스)

  • Yim, Byung-Seung;Jeon, Sung-Ho;Song, Yong;Kim, Yeon-Hee;Kim, Joo-Heon;Kim, Jong-Min
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.73-73
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    • 2009
  • In this sutdy, a new class ACA(Anisotropic Conductive Adhesive) with low-melting-point alloy(LMPA) and self-organized interconnection method were developed. This developed self-organized interconnection method are achieved by the flow, melting, coalescence and wetting characteristics of the LMPA fillers in ACA. In order to observe self-interconnection characteristic, the QFP($14{\times}14{\times}2.7mm$ size and 1mm lead pitch) was used. Thermal characteristic of the ACA and temperature-dependant viscosity characteristics of the polymer were observed by differential scanning calorimetry(DSC) and torsional parallel rheometer, respectively. A electrical and mechanical characteristics of QFP bonding were measured using multimeter and pull tester, respectively. Wetting and coalescence characteristics of LMPA filler particles and morphology of conduction path were observed by microfocus X-ray inspection systems and cross-sectional optical microscope. As a result, the developed self-organized interconnection method has a good electrical characteristic($2.41m{\Omega}$) and bonding strength(17.19N) by metallurgical interconnection of molten solder particles in ACA.

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Critical Current Density Distribution Analysis of HTS Tape (고온초전도 테이프의 임계전류밀도 분포 해석)

  • 강준선;나완수;권영길;손명환;김석환
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.277-280
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    • 2002
  • It is well known that the critical current of a HTS tape has anisotropic characteristic in magnetic field. We are interested in critical current density distribution of a HTS tape. We assumed the experimentally obtained Ic-B curves do represent the local properties of HTS tapes and calculated the critical current density distribution of HTS tapes using numerical method. Also we predicted the critical current of the tapes.

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A Study of Spatial Model for AMR Magnetometer In Wireless Sensor Network (센서네트워크 응용을 위한 AMR 자기센서의 공간적 출력 신호 모델링 연구)

  • Kim, Ki-Tae;Kim, Keon-Wook
    • Proceedings of the IEEK Conference
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    • 2008.06a
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    • pp.953-954
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    • 2008
  • Wireless Sensor Network (WSN) surveillance applications usually employed magnetometer for recognizing the ferrous objects. Novel magnetic sensing model which includes azimuth parameter is suggested to understand the anisotropic characteristic of magnetic field through numerous outdoor experiments.

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Characteristic Analysis of the ALA-type Reluctance Synchronous Motor (ALA형 리럭턴스 동기 전동기의 특성해석)

  • Choi, Kyeong-Ho;Kim, Nam-Hun;Balk, Won-Sik;Kim, Dong-Hee;Hwang, Don-Ha;Kim, Min-Huei
    • Proceedings of the KIEE Conference
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    • 2002.07b
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    • pp.955-957
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    • 2002
  • This paper presents a detailed characteristic of reluctance synchronous motor (RSM) which has a axially laminated anisotropic (ALA) structure of the rotor. First of all, the analysis of a magnetic circuit field between stator and rotor should be achieved in order to predict the performance characteristics of the RSM. For the analysis of a magnetic circuit field, the finite element (FE) analysis is used. The analytical result of the inductance, flux distribution, vector potential and simulation results shows along with the load condition.

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Analysis of the Magnetizing Characteristics on Anisotropic Permanent Magnet (이방성영구자석의 착자특성 해석)

  • Lee, Hyang-Beom;Hahn, Song-Yop;Hong, Jung-Pyo;Choi, Hong-Soon
    • Proceedings of the KIEE Conference
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    • 1991.07a
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    • pp.118-121
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    • 1991
  • The characteristics of magnetizing system considering the anisotropy and the nonlinearity are analyrized using PEM in This paper. The case of magnetizing the ferrite magnet with 12 poles is analyrized. The anisotropy characteristic is considered when ferrite magnet which is widely used as permanent magnet is magnetized. The Nonlinear characteristic of magnetizing yoke aid ferrite is considered because the current is in the saturation region. When the magnetizing current value is over the optimum value, the magnet is magnetized with 24 poles. This is not the case of our expectation. Thus, for the case of our expected magnetizing form, it is the conclusion that the optimum magnetizing current value is selected.

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Vibration Characteristics Analysis of a Piezoelectric Disc or Torsional Transducers (비틀림 진동 변환기용 압전 원판의 진동특성 해석)

  • Lee, Jung-Hyun;Kim, Jin-Oh
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.12 s.105
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    • pp.1416-1421
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    • 2005
  • This paper presents an analytical approach for the vibration characteristics of a piezoelectric disc for torsional vibration transducers. The characteristic equation of the piezoelectric annular disc has been derived from Gibbs' free energy equations and mechanical and electrical equilibrium. With an anisotropic material properties of the disc, the characteristic equation has yielded resonance frequencies. Numerically-calculated results have been compared with the results obtained by the finite element analysis and experiments and have confirmed the validity of the theoretical analysis.

Inherent Strength Anisotropy of the Shale in Daegu Region (대구지역 셰일 압축강도의 고유이방성에 관한 연구)

  • Lee, Younghuy;Kim, Heedong
    • Journal of the Korean GEO-environmental Society
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    • v.9 no.7
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    • pp.45-51
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    • 2008
  • Triaxial compression tests on anisotropic rock specimens are carried out to investigate the failure strength characteristic of anisotropic rocks. The test core specimens were obtained in Daegu region. Test specimens are rock cores with the 7 different angles of bedding plane. The applied confining pressures were 5, 10, 20, 30, 40 MPa, and the rate of displacement was adopted 0.1%/min to fail the specimen within 5-15 min. The results were analyzed by using the failure criteria for anisotropic rocks proposed by Hoek & Brown (1980) and Jaeger (1960). The results of this study are summerised as follows: The results of inherent anisotropy show the shoulder type of anisotropy, and the effect of anisotropy is reduced as the confining pressure increases. The compressive strength of anisotropic rock shows the highest value at the ${\beta}$ (the angle of bedding plane) = $0^{\circ}$ and $90^{\circ}$ and the lowest value at $30^{\circ}$. The Hoek & Brown failure criterion for anisotropic rocks gives a relatively good agreement with the measured strength in all the range of ${\beta}$ angles, but the theory of Jaeger shows a reasonable agreement only in the range of ${\beta}=15^{\circ}$ and $45^{\circ}$.

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