• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1485-1495
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• 2003

We investigate the triboelectrostatic separation of polyvinylchloride (PVC) from mixed plastics in the laboratory scale triboelectrostatic separation system. The flow and electric fields in the precipitator are obtained from the numerical solution of finite volume method. Using these flow and electric fields, we solved the particle motion equation considering the inertia, drag, gravity and electrostatic forces acted on the particles. The particle trajectories are obtained using a Lagrangian method as a function of different important variables such as Reynolds number, Stokes number, electrostatic force, electric charge and electric field distribution, inclined angle of plane electrodes, particle rebounding, particle charge decay rate after impact on the electrode surface, etc., in order to determine the optimal design conditions. The present predicted results for the cumulative yield represent well the experimental ones.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.2
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• pp.40-45
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• 1986

In this paper, the I-resistance curve of low-carbon steel with 3 mm thickness was investigated for various crack ratios. The experiments were carried out for the center cracked tension (CCT) specimen with about 50 mm width on an instron machine. The plane stress fracture toughness obtained by the Simpson's formula was Ii. = 24.96 kgffmm. Simpson's formula which considers crack growth in obtaining J integral showed more conservative lin than Rice's and Sumpter's. For materials that may be approximated by the Ramberg and Osgood stress strain law, the relevant crack parameters like the J integral, load line displacement are approximately normalized. Crack driving forces in terms of the I integral are computed for low-carbon steel CCT specimen using the above estimation scheme. Comparison of the prediction with actual experimental measurements by Simpson's formula showed good agreement for several different sized specimen.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.1
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• pp.39-41
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• 2016

In the paper, we propose an stable walking algorithm of biped robot on the ground and working motion stabilization algorithm against external disturbances. We propose obstacle hurdling, incline walking, and going-up stairs algorithm by using infrared sensors and F/T sensors. Also, posture stabilization algorithm against external forces is designed using F/T sensors. Infrared sensors are used to detect the obstacles in he working environment and F/T sensors are used to obtain the ZMP of biped robot. The experimental results show that the biped robot performs obstacle avoidance, obstacle hurdling, walking on the inclined plane by using the proposed walking moton stabilization algorithm.

• Structural Engineering and Mechanics
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• v.58 no.1
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• pp.103-119
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• 2016

Multi-storey frame structures are frequently exposed to static and dynamic forces. Therefore analyses of static (buckling) and dynamic stability come into prominence for these structures. In this study, the effects of number of storey, static and dynamic load parameters, crack depth and crack location on the in-plane static and dynamic stability of cracked multi-storey frame structures subjected to periodic loading have been investigated numerically by using the Finite Element Method. A crack element based on the Euler beam theory is developed by using the principles of fracture mechanics. The equation of motion for the cracked multi-storey frame subjected to periodic loading is achieved by Lagrange's equation. The results obtained from the stability analysis are presented in three dimensional graphs and tables.

• Structural Engineering and Mechanics
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• v.31 no.3
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• pp.297-314
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• 2009

When the temperature of a structure varies, there is a tendency to produce changes in the shape of the structure. The resulting actions may be of considerable importance in the analysis of the structures having non-prismatic members. Therefore, this study aimed to investigate the modeling, analysis and behavior of the non-prismatic members subjected to temperature changes with the aid of finite element modeling. The fixed-end moments and fixed-end forces of such members due to temperature changes were computed through a comprehensive parametric study. It was demonstrated that the conventional methods using frame elements can lead to significant errors, and the deviations can reach to unacceptable levels for these types of structures. The design formulas and the dimensionless design coefficients were proposed based on a comprehensive parametric study using two-dimensional plane-stress finite element models. The fixed-end actions of the non-prismatic members having parabolic and straight haunches due to temperature changes can be determined using the proposed approach without necessitating a detailed finite element model solution. Additionally, the robust results of the finite element analyses allowed examining the sources and magnitudes of the errors in the conventional analysis.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.82-88
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• 2002

This paper deals with the free vibrations of horizontally curved beams with transition curve. Based on the dynamic equilibrium equations of a curved beam element subjected to the stress resultants and inertia forces, the governing differential equations are derived for the out-of-plane vibration of curved beam wish variable curvature. This equations are applied to the beam having transition curve in which the third parabolic curve is chosen in this study. The differential equations are solved by the numerical procedures for calculating the natural frequencies. As the numerical results, the various parametric studies effecting on natural frequencies are investigated and its results are presented in tables and figures. Also the laboratory scaled experiments were conducted for verifying the theories developed herein.

• Ocean Systems Engineering
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• v.10 no.3
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• pp.289-316
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• 2020

In the present paper, the effect of the location of stern planes on the flow entering the submarine propeller is studied numerically. These planes are mounted on three longitudinal positions on the submarine stern. The results are presented considering the flow field characteristics such as non-dimensional pressure coefficient, effective drag and lift forces on the stern plane, and the wake flow formed at the rear of the submarine where the propeller is located. In the present study, the submarine is studied at fully immersed condition without considering the free surface effects. The numerical results are verified with the experimental data. It is concluded that as the number of planes installed at the end of the stern section along the submarine model increases, the average velocity, width of the wake flow and its turbulence intensity formed at the end of the submarine enhance. This leads to a reduction in the non-uniformity of the inlet flow to the propulsion system.

• Structural Engineering and Mechanics
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• v.54 no.5
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• pp.987-998
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• 2015

In this paper, free vibrations of a clamped-clamped double-walled carbon nanotube (DWNT) under axial force is studied. By utilizing Euler-Bernoulli beam theory, each layer of DWNT is modeled as a beam. In this analysis, nonlinear form of interlayer van der Waals (vdW) forces and nonlinearities aroused from mid-plane stretching are also considered in the equations of motion. Further, direct application of multiple scales perturbation method is utilized to solve the obtained equations and to analyze free vibrations of the DWNT. Therefore, analytical expressions are found for vibrations of each layer. Linear and nonlinear natural frequencies of the system and vibration amplitude ratios of inner to outer layers are also obtained. Finally, the results are compared with the results obtained by Galerkin method.

• Advances in aircraft and spacecraft science
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• v.6 no.4
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• pp.297-314
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• 2019

Dynamic stability of a porous metal foam nano-dimension plate on elastic substrate exposed to bi-axial time-dependent forces has been studied via a novel 3-variable plate theory. Various pore contents based on uniform and non-uniform models have been introduced. The presented plate model contains smaller number of field variables with shear deformation verification. Hamilton's principle will be utilized to deduce the governing equations. Next, the equations have been defined in the context of Mathieu-Hill equation. Correctness of presented methodology has been verified by comparison of derived results with previous data. Impacts of static and dynamical force coefficients, non-local coefficient, foundation coefficients, pore distributions and boundary edges on stability regions of metal foam nanoscale plates will be studied.

• Proceedings of the KSEG Conference
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• 2005.04a
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• pp.101-106
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• 2005

The three-dimensional Tomography developed by Kim and Bae(2004) was applied to 64,024 P and 64,618 S wave arrival times observed at 238 seismic stations for 4050 local earthquakes in the depth range from 0 to 300 km in and around Hokkaido, Japan. High and low velocity zones for Vp/Vs were clearly imaged in and around Hokkaido. The upper seismic planes of the double seismic zone (DSZ) were found in the subducted Pacific Plate beneath Hokkaido at depth of 40- 80 km, which produced high seismicity around Hokkaido. The findings of high Vp/Vs anomalies beneath the Moho discontinuity supports an evidence of a surface triple-collision hypothesis prepared by Moriya(1994) that the Kuril Arc(Okhotsk Plate or North American Plate) is colliding against the NE Japanese Arc(Amurian Plate or Eurasian Plate), along and beneath the Hidaka Mountain Range, and at the same time the Pacific Plate is subducting into these two plates, making an equilibrium of tectonic forces along the Hikada Mountain Range (HMR) corner and the central tectonic axis(142 ~ 143E) in Hokkaido. The low Vp and Vs were also found in east and west along the central tectonic axis in which the focal mechanism represents the extensional forces. These phenomena are also consistent with low Bouguer gravity anomalies in this region. It is understood why most of great earthquakes occurred outside Hokkaido where the balance of tectonic forces are breaking from the triple junction of three tectonic forces in Hokkaido.