• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.195-201
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• 2002

In this study, an equation is proposed to estimate the limit velocity for lateral stable bed in a curved channel stream. The stable bed on lateral direction is satisfied when there is no more deformation occurs on the transverse bed slope and non-scouring condition in a bend. A theoretical equation for limit velocity is derived using a transverse bed slope model. So, the limit velocity has its theoretical background in the equilibrium of two forces, lateral shear force at the bed due to longitudinal flow and the corresponding lateral bed shear force. To verify the equation, data from four natural river channels were used. There is good agreement between the calculated values using this equation and the measured values. The corrections in equation was found to be correlated with the averaged particle Froude number.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.53-58
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• 2017

This paper describes liquidity evaluation on the horizontal branch pipe connected to a food waste disposer and performance of five disposers marketed. Experimental apparatus for analyzing the five disposers has been introduced to measure vibration, sound level and power consumption of the disposers. Simulator for analyzing the required water velocity to avoid waste jam inside the pipe connected to a food waste disposer has been designed and constructed. The simulator can control some experimental parameters: pipe slope, disposer supply water quantity, food waste materials and operation time of a disposer. Throughout the experimental measurements of the disposers marketed, it is found that the time need to crash food waste is about 20 seconds on the average. At the same flow condition, increase rate of internal water velocity is accelerated as the pipe slope increases. The water velocity inside the pipe having 50 A and slope of 1/50 is 0.26 m/s when the water flowrate to supply the disposer is 16 l pm. Considering the specific gravity and adhesion property of food waste, water velocity of the horizontal branch pipe connected to a food waste disposer need to excess 0.26 m/s at least to avoid the waste blockage inside the pipe.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2266-2268
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• 2009

In this paper, a simple method of angle velocity estimation is presented for a passive dynamic biped robot. The estimation problem is not an easy task because its dynamic model is a hybrid system involved with an impact condition. Instead of designing a complex observer for hybrid systems we simply utilize the impact condition to reset the initial condition of the high-pass filter when the non-support leg hits the slope. The approach has been verified by simulation results.

• Computers and Concrete
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• v.19 no.5
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• pp.527-535
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• 2017

In this study, an aging deformation statistical model for a unique high and steep rock slope was proposed, and the aging characteristic of the slope deformation was better reflected. The slope displacement was affected by multiple-environmental factors in multiple scales and displayed the same tendency with a rising water level. The statistical model of the high and steep rock including non-aging factors was set up based on previous analyses and the study of the deformation and residual tendency. The rule and importance of the water level factor as a non-aging unit was analyzed. A partitioned statistical model and mutation model were established for the comprehensive cumulative displacement velocity with the monitoring study under multiple factors and multiple parameters. A spatial model was also developed to reflect and predict the whole and sectional deformation character by combining aging, deformation and space coordinates. A neural network model was built to fit and predict the deformation with a high degree of precision by mastering its feature of complexity and randomness. A three-dimensional finite element model of the slope was applied to approach the structure character using numerical simulations. Further, a three-dimensional finite element model of the slope and dam was developed, and the whole deformation state was analyzed. This study is expected to provide a powerful and systematic method to analyze very high, important and dangerous slopes.

• Earthquakes and Structures
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• v.21 no.6
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• pp.601-612
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• 2021

The paper concerns the selection of a design accelerograms used for the slope stability assessment under earthquake excitation. The aim is to experimentally verify the Arias Intensity as an indicator of the excitation threat to the slope stability. A simple dynamic system consisting of a rigid block on a rigid inclined plane subjected to horizontal excitation is adopted as a slope model. Strong ground motions recorded during earthquakes are reproduced on a shaking table. The permanent displacement of the block serves as a slope stability indicator. Original research stand allows us to analyse not only the relative displacement but also the acceleration time history of the block. The experiments demonstrate that the Arias Intensity of the accelerogram is a good indicator of excitation threat to the stability of the slope. The numerical analyses conducted using the experimentally verified extended Newmark's method indicate that both the Arias Intensity and the peak velocity of the excitation are good indicators of the impact of dynamic excitation on the dam's stability. The selection can be refined using complementary information, which is the dominant frequency and duration of the strong motion phase of the excitation, respectively.

• Korean Journal of Applied Biomechanics
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• v.16 no.2
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• pp.1-8
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• 2006

The purpose of this study was to evaluate normalized jerk according to shoes, slope, and velocity during walking. Eleven different test subjects used three different types of shoes (running shoes, mountain climbing boots, and elevated forefoot walking shoes) at various walking speeds(1.19, 1.25, 1.33, 1.56, 1.78, 1.9, 2, 2.11, 2.33m/sec) and gradients(0, 3, 6, 10 degrees) on a treadmill. Since there were concerns about using the elevated forefoot shoes on an incline, these shoes were not used on a gradient. Motion Analysis (Motion Analysis Corp. Santa Rosa, CA USA) was conducted with four Falcon high speed digital motion capture cameras. Utilizing the maximum smoothness theory, it was hypothesized that there would be differences in jerk according to shoe type, velocity, and slope. Furthermore, it was assumed that running shoes would have the lowest values for normalized jerk because subjects were most accustomed to wearing these shoes. The results demonstrated that elevated forefoot walking shoes had lowest value for normalized jerk at heel. In contrast, elevated forefoot walking shoes had greater normalized jerk at the center of mass at most walking speeds. For most gradients and walking speeds, hiking boots had smaller medio-lateral directional normalized jerk at ankle than running shoes. These results alluded to an inverse ratio for jerk at the heel and at the COM for all types of shoes. Furthermore, as velocity increased, medio-lateral jerk was reduced for all gradients in both hiking boots and running shoes. Due to the fragility of the ankle joint, elevated forefoot walking shoes could be recommended for walking on flat surfaces because they minimize instability at the heel. Although the elevated forefoot walking shoes have the highest levels of jerk at the COM, the structure of the pelvis and spine allows for greater compensatory movement than the ankle. This movement at the COM might even have a beneficial effect of activating the muscles in the back and abdomen more than other shoes. On inclines hiking boots would be recommended over running shoes because hiking boots demonstrated more medio-lateral stability on a gradient than running shoes. These results also demonstrate the usefulness of normalized jerk theory in analyzing the relationship between the body and shoes, walking velocity, and movement up a slope.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1560-1565
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• 2007

In this study, Chiu's velocity distribution equation recently developed from the probability and entropy concepts is used to establish a linkage between the mean velocity obtained from the Manning's equation and the corresponding velocity distribution in a channel cross section. The linkage to be established enables computing the velocity distribution along with the mean velocity, from simple hydraulic data such as Manning's n, hydraulic radius and channel slope irrespective of including sediment or not.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1306-1310
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• 2009

The roughness coefficients were estimated by the Manning's equation for the measured stage and flow velocity of Bocheong stream basin in Kum river. The relationships between the estimated roughness coefficients and the geomorphologic factors were formulated by the linear, logarithmic, exponential and power type function, thereafter correlation equations were presented. The correlation analysis was performed between the measured stream length and the basin area of Bocheong stream basin by the linear, logarithmic, exponential and power type function, and correlation equation for the stream length was given. The roughness coefficient has strong correlationship with stream slope, but low correlation coefficients with stream length and basin area. For the correlationship with the roughness coefficients and the stream slope, the logarithmic type function has the smallest correlation coefficient, on the other hand, the exponential type function has the largest correlation coefficient. For the relationship between the stream length and the basin area, the correlation coefficient of the logarithmic type function shows the smallest value, linear type function shows the largest value.

• Transactions of Materials Processing
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• v.20 no.4
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• pp.284-290
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• 2011

The front end bending(FEB) behavior of material that usually occurs in plate rolling is investigated. In this paper, a rollbite profile map approach that systematically predicts the FEB slope is presented. It is based on the concurrent use of shape factors and reduction ratios to ensure an accurate value of the FEB and its slope. In order to obtain the unit roll-bite profile map, the FEB slope model was decomposed into a temperature deviation component and a roll-velocity deviation component. By mapping the results of a series of finite element analyses to the unit functions of the roll-bite profile map, it was possible to obtain a realistic prediction of the FEB slope applicable to an actual plate rolling process. Thereby, the usefulness of the present approach is clearly demonstrated.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.5
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• pp.575-582
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• 2019

Advanced driving assist system can support safety of driver and passengers which may require vehicle dynamics states as well as road geometry. It is essential to have in real-time estimation of related variables and parameters. Among the road geometry parameters, road slope angle which can not be measured is essential parameter in pose estimation, adaptive cruise control and others on sag road. In this paper, Kalman filter based method for the estimation of the vehicle dynamics and road slope angle using a nonlinear vehicle model is proposed. It uses a combination of Kalman filter as Cascade Extended Kalman Filter. CEKF uses measured vehicle states such as yaw rate, longitudinal/lateral acceleration and velocity. Unknown vehicle parameters such as center of gravity and inertia are obtained by 2 D.O.F lateral model and experimentally. Simulation and Experimental tests conducted with commercialized vehicle dynamics model and real-car.