• Title, Summary, Keyword: Displacement rate

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Dynamic displacement estimation by fusing biased high-sampling rate acceleration and low-sampling rate displacement measurements using two-stage Kalman estimator

  • Kim, Kiyoung;Choi, Jaemook;Koo, Gunhee;Sohn, Hoon
    • Smart Structures and Systems
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    • v.17 no.4
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    • pp.647-667
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    • 2016
  • In this paper, dynamic displacement is estimated with high accuracy by blending high-sampling rate acceleration data with low-sampling rate displacement measurement using a two-stage Kalman estimator. In Stage 1, the two-stage Kalman estimator first approximates dynamic displacement. Then, the estimator in Stage 2 estimates a bias with high accuracy and refines the displacement estimate from Stage 1. In the previous Kalman filter based displacement techniques, the estimation accuracy can deteriorate due to (1) the discontinuities produced when the estimate is adjusted by displacement measurement and (2) slow convergence at the beginning of estimation. To resolve these drawbacks, the previous techniques adopt smoothing techniques, which involve additional future measurements in the estimation. However, the smoothing techniques require more computational time and resources and hamper real-time estimation. The proposed technique addresses the drawbacks of the previous techniques without smoothing. The performance of the proposed technique is verified under various dynamic loading, sampling rate and noise level conditions via a series of numerical simulations and experiments. Its performance is also compared with those of the existing Kalman filter based techniques.

Plastic Displacement Estimates in Creep Crack Growth Testing (크리프 균열 성장 실험을 위한 소성 변위 결정법)

  • Huh Nam-Su;Yoon Kee-Bong;Kim Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.10
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    • pp.1219-1226
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    • 2006
  • The ASTM test standard recommends the use of the compact tension specimen for creep crack growth rates measurement. In the creep crack growth rate test, the displacement rate due to creep is obtained by subtracting the contribution of elastic and plastic components from the total load line displacement rate based on displacement partitioning method fur determining $C^*-integral$, which involves Ramberg-Osgood (R-O) fitting procedures. This paper investigates the effect of the R-O fitting procedures on plastic displacement rate estimates in creep crack growth testing, via detailed two-dimensional and three-dimensional finite element analyses of the standard compact tension specimen. Four different R-O fitting procedures are considered; (i) fitting the entire true stress-strain data up to the ultimate tensile strength, (ii) fitting the true stress-strain data from 0.1% strain to 0.8 of the true ultimate strain, (iii) fitting the true stress-strain data only up to 5% strain, and (iv) fitting the engineering stress-strain data. It is found that the last two procedures provide reasonably accurate plastic displacement rates and thus should be recommended in creep crack growth testing. Moreover, several advantages of fitting the engineering stress-strain data over fitting the true stress-strain data only up to 5% strain are discussed.

Effect of Test Parameter on Ball Shear Properties for BGA and Flip Chip Packages (BGA 및 Flip Chip 패키지의 볼전단 특성에 미치는 시험변수의 영향)

  • Gu, Ja-Myeong;Jeong, Seung-Bu
    • Proceedings of the KWS Conference
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    • pp.19-21
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    • 2005
  • The ball shea. tests for ball grid array (BGA) and flip chip packages were carried out with different displacement rates to find out the optimum condition of the displacement rate for this test. The BGA packages consisted of two different kinds of solder balls (eutectic Sn-37wt.%Pb and Sn-3.5wt.%Ag) and electroplated Au/Ni/Cu substrate, whereas the flip chip package consisted of electroplated Sn-37Pb solder and Cu UBM. The packages were reflowed up to 10 times, or aged at 443 K up to 21 days. The variation of the displacement rate resulted in the variations of the shear properties such as shear force, displacement rate at break, fracture mode and strain rate sensitivity. The increase in the displacement rate led to the increase of the shear force and brittleness of solder joints.

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Survey on the Occurrence of Abomasal Displacement of Dairy Cattle in Tokachi Shimizu Cho, Hokkaido, Japan (일본국 북해도 십승청수정에 있어서의 유우의 제사위전위증발생에 관한 조사연구: 특히 전용수술차도입후의 현황)

  • Kweon Oh-Kyeong
    • Journal of Veterinary Clinics
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    • v.4 no.1
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    • pp.403-408
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    • 1987
  • The occurrence of abomasal displacement in Tokachi Shimizu Cho, Hokkaido, Japan has been surveyed in relation to milk production from 1979 to 1986. In 1983 when dairy cows produced over 5.000kg of milk yield per year. the occurrence rate of abomasal displacement increased over 1%. Thereafter, the occurrence rate increased markedly as the milk production approached 6.000kg. In order to increase the number of cows which can be surgically corrected, a special ambulatory vehicle for surgery was designed. Since more cows were surgically corrected. there was a subsequent decrease in the culling rate of cows with abomasal displacement. The present survey indicated that the occurrence rate of abomasal displacement was closely related to milk production, and that surgical correction was a very effective method to treat this condition.

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The Effect of Flow Rate on the Process of Immiscible Displacement in Porous Media (다공성 매체 내 비혼성 대체 과정에서 주입 유량이 거동 양상에 미치는 영향)

  • Park, Gyuryeong;Kim, Seon-ok;Lee, Minhee;Wang, Sookyun
    • Journal of Soil and Groundwater Environment
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    • v.23 no.1
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    • pp.1-13
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    • 2018
  • A series of experiments using transparent micromodels with an artificial pore network etched on glass plates was performed to investigate the effects of flow rate on the migration and distribution of resident wetting porewater (deionized water) and injecting non-wetting fluid (n-hexane). Multicolored images transformed from real RGB images were used to distinguish n-hexane from porewater and pore structure. Hexane flooding followed by immiscible displacement with porewater, migration through capillary fingering, preferential flow and bypassing were observed during injection experiments. The areal displacement efficiency increases as the injection of n-hexane continues until the equilibrium reaches. Experimental results showed that the areal displacement efficiency at equilibrium increases as the flow rate increases. Close observation reveals that preferential flowpaths through larger pore bodies and throats and clusters of entrapped porewater were frequently created at lower flow rate. At higher flow rate, randomly oriented forward and lateral flowpaths of n-hexane displaces more porewater at an efficiency close to stable displacement. It may resulted from that the pore pressure of n-hexane, at higher flow rate, increases fast enough to overcome capillary pressure acting on smaller pore throats as well larger ones. Experimental results in this study may provide fundamental information on migration and distribution of immiscible fluids in subsurface porous media.

The Effect of Displacement Rate on Shear Characteristics of Geotextile-involved Ceosynthetic Interfaces (지오텍스타일이 포함된 토목섬유 경계면의 전단특성에 대한 변위속도 효과)

  • 김진만
    • Journal of the Korean Geotechnical Society
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    • v.19 no.1
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    • pp.173-180
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    • 2003
  • In spite of its potential importance in the assessment of geosynthetic-related dynamic problems, no serious attempt has yet been made to investigate a probable dependence of dynamic friction resistance of the geosynthetic interface on shear displacement rate. Hence, an experimental study of geosynthetics was carried out on a shaking table, and the relationship between dynamic friction resistance and shear displacement rate of geosynthetic interfaces was investigated. A cyclic, displacement rate-controlled experimental setup was used. The subsequent multiple rate tests showed that interfaces that involve geotextiles have such unique shearing characteristics that shear strengths tend to increase with displacement rate. In contrast, once submerged with water, the shear strength appears to be no longer dependent on the displacement rate, partly due to lubrication effect of water trapped inside the interface. The results of the experimental study can be used in the seismic safety assessment of a landfill cover and slope where the geosynthetic materials are exposed to a relatively low normal stress.

A STUDY ON DIFFERENT AMOUNT OF DENTURE BASE DISPLACEMENT USING SOFT DENTURE RELINING MATERIAL UNDER MASTICATORY FORCE (국소의치상을 위한 연성 이장재사용시 교합압에 따른 의치상 변위(Displacement)량 비교)

  • Lee, Ho-Yong
    • The Journal of Korean Academy of Prosthodontics
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    • v.36 no.1
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    • pp.18-25
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    • 1998
  • The purpose of this study was to determine how to use soft relining material by observing an amount of denture displacement according to the different base area of residual ridge and thickness of soft relining material under masticatory force. Stone models that simulated residual ridge were made with different amount of denture base area and denture was fabricated by conventional heat curing resin with usual manner on the model and relined by silicone type soft relining material with different thickness. Specimen was examined the amount of denture displacement by Instron within range of normal occlusal force. The results were as following : 1. The increasing rate of denture displacement was higher than that of soft relining material thickness. 2. The amount of denture displacement decreased 1.7 times when base area became double at same thickness of soft relining material 3. The increasing rate of denture displacement was higher than that of occlusal force

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The Length Effects of Downward Inclined Interface about Bimaterials (이종재료 하향 경사계면의 길이 효과)

  • Choi, Byung Sun
    • Journal of the Korean Society of Mechanical Technology
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    • v.19 no.2
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    • pp.149-155
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    • 2017
  • This study discusses the length effect of the downward inclined surface to apply the inclined interface surface design of the composite material under shear loading. The fracture parameter is analyzed by finite element method of the ANSYS. If the negative shear displacement is applied, energy release rate is reduced further to about the increasing inclined length, and the positive shear displacement applied, it had increased rather. If the negative shear displacement is applied, the reduction in the energy release rate in crack tip is found to be affected by the reduction in shear stress. If the positive shear displacement is applied, the increasing in the energy release rate in the crack tip is found to be affected by the increase in shear stress.

Study on Vertical Dynamics Compensation for Wobbling Effect Mitigation of Electrostatically Levitated Gyroscope

  • Lee, Jongmin;Song, Hyungmin;Sung, Sangkyung;Kim, Chang Joo;Lee, Sangwoo
    • International Journal of Aeronautical and Space Sciences
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    • v.15 no.3
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    • pp.293-301
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    • 2014
  • We present a study of vertical dynamics control of an electrostatically levitated gyro-accelerometer considering the wobbling effect and propose a tilt stabilization method with newly introduced control electrodes. Typically, a rotor in a vacuum rotates at high velocity, which may create a drift rate and lead to displacement instability due to the tilt angle of the rotor. To analyze this, first we set up a vertical dynamic equation and determined simulation results regarding displacement control. After deriving an equation for drift dynamics, we analyzed the drift rate of the rotor and the wobbling effect for displacement control quantitatively. Then, we designed new sub-electrodes for moment control that will decrease the drift amplitude of wobbling dynamics. Finally, a simulation study demonstrated that the vertical displacement control with the wobbling compensation electrodes mitigated the rotor's drift rate, showing the effectiveness of the newly proposed control electrodes.

Development of a Flow Rate Sensor Using 2-way Cartridge Valve (2-유로 카트리지 밸브를 이용한 유압용 유량 센서의 개발)

  • 홍예선;이정오
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2381-2389
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    • 1993
  • In this paper the design and test results of a dynamic flow rate sensor was reported. This sensor comprises an 2-way cartridge valve as standard hydraulic component and a displacement sensor. Its working principle bases on the linear relationship between the flow rate and the piston displacement of 2-way cartridge valves under constant pressure drop. This principle is well known, however it is not easy to develop a flow rate sensor with the measurement range of 300 1/min, pressure loss of less than 8 bar at 300 1/min, maximum linearity error of less than $\pm$1% and the maximum rising time of 10 ms. This paper describes the design procedure of the flow rate sensor, the improvement procedure of static performance and test method and results of dynamic performance.