• Smart Structures and Systems
• /
• 제17권4호
• /
• pp.647-667
• /
• 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.

• 대한기계학회논문집A
• /
• 제30권10호
• /
• pp.1219-1226
• /
• 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.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
• /
• pp.19-21
• /
• 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.

• 한국임상수의학회지
• /
• 제4권1호
• /
• pp.403-408
• /
• 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.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제23권1호
• /
• pp.1-13
• /
• 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.

• 한국지반공학회논문집
• /
• 제19권1호
• /
• pp.173-180
• /
• 2003

토목섬유 경계 접촉면들의 동적거동을 이해하는데 매우 중요할 수도 있음에도 불구하고 접촉면들의 동적마찰저항과 변위속도 관계에 관한 연구가 아직까지는 미비한 실정이다. 이에 따라 토목섬유에 대한 실험적 인 연구를 진동대를 이용하여 수행하였다. 반복적, 변위속도 조절장치를 개발하여 사용하였으며 토목섬유 경계 접촉면들의 동적마찰저항과 변위속도사이의 관계를 조사하였다. 실험으로부터 지오텍스타일이 포함된 경계 접촉면에서는 변위속도 증가에 따라 전단강도도 증가한다는 중요한 결과를 얻었다. 이와는 달리 수침상태에서는 접촉면 사이에 갇힌 물에 의한 윤활 효과 등으로 인해 접촉 전단강도가 변위속도에 민감하지 않다는 결과를 얻었다. 본 시험결과는 토목섬유에 비교적 낮은 수직응력이 작용하는 매립장 덮개 및 사면의 동적안정 해석등에 적용할 수 있다.

• 대한치과보철학회지
• /
• 제36권1호
• /
• pp.18-25
• /
• 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

• International Journal of Aeronautical and Space Sciences
• /
• 제15권3호
• /
• pp.293-301
• /
• 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.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
• /
• pp.61-65
• /
• 2008

This study, having combined and displaced blast furnace slag("BS" hereinafter) known as admixture material that delays hydration reaction with coarse particle cement("CC" hereinafter) collected in particle classification method during ordinary portland cement("OPC" hereinafter), reviewed the hydration heat characteristics affecting the concrete. To reduce hydration heat, the study plain-mixed which used 100% OPC for W/B 50% level 1, displaced CC at level 3 of 25%, 50% and 75% for OPC, and by displacing BS with admixture material at level 5 of 0%, 20%, 40%, 60% and 80% for cement(OPC+CC), experimented totally 16 batches. As a result of experiment, in the case of flow, the more CC displacement rate increased, the more it tended to decrease, and the more BS displacement rate increased, the more it decreased. Also, as for simple adiabatic temperature rise by the CC and BS displacement rates, it decreased as displacement rate increased, and particularly in the case of displaced BS of 80%, It showed temperature reduction effect of about 63% companing with plain. Compressive strength decreased in proportion to displacement rate, however strength reduction increment was shown to decrease with age progress.

• 대한기계학회논문집
• /
• 제17권9호
• /
• pp.2381-2389
• /
• 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.