• Journal of Institute of Control, Robotics and Systems
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• v.12 no.5
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• pp.457-463
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• 2006

Recently proposed control scheme for a stable teleoperation, which was based on two-port time-domain passivity approach[21], has been successful for a contact with high stiffness environments. However, we found several conservatisms during the contact with deformable environments and unconstrained motion. The two-port time-domain passivity controller was excessively dissipating energy even though it was not necessary for some cases of an unconstrained motion and soft contact. The main reason of those conservatisms was on the fact that the two-port time-domain passivity controller was activated without considering the amount of energy dissipation at the master and slave manipulators. Especially, the exclusion of the slave manipulator from the two-port was the dominant reason of the conservatisms. In this paper, we consider the amount of energy dissipation at slave manipulator for designing the time-domain passivity observer and controller. The measured interaction force between slave manipulator and environment allow the time-domain passivity observer to include the amount of energy dissipation at the slave manipulator. Based on the modified passivity observer, reference energy following method[24] is applied to satisfy the passivity condition in real-time. The feasibility of the developed methods is proved with experiments. Improved performance is obtained for an interaction with deformable environments and an unconstrained motion.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.6
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• pp.826-831
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• 2007

In this paper, we proposed new method of soft-motor control which is control method allowing motor control within control stage by using EtherCAT which is real time motion control network of high speed. We also evaluated performance of the system and verified possibility and effectiveness of application into real system through experiments.

• Journal of Integrative Natural Science
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• v.12 no.4
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• pp.105-115
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• 2019

In this paper, a prediction system is proposed to control the brightness of smart street lamps by predicting the moving path through the reduction of consumption power and information of pedestrian's past moving direction while meeting the function of existing smart street lamps. The brightness of smart street lamps is adjusted by utilizing the walk tracking vector and soft hand-off characteristics obtained through the motion sensing sensor of smart street lamps. In addition, the motion vector is used to analyze and predict the pedestrian path, and the GPU is used for high-speed computation. Pedestrians were detected using adaptive Gaussian mixing, weighted difference imaging, and motion vectors, and motions of pedestrians were analyzed using the extracted motion vectors. The preprocessing process using linear interpolation is performed to improve the performance of the proposed prediction system. Fuzzy prediction system and neural network prediction system are designed in parallel to improve efficiency and rough set is used for error correction.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.284-291
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• 2006

This paper presents a seismic response analysis of bridge structures considering foundation-soil interaction and multi-support input motion. In the earthquake analysis of structures it is usually assumed that the input ground motion is the same at all supports. However, this assumption is not justified for long structures like bridges, because observations have shown the earthquake ground motion can vary considerably within relatively small distances. When the soil under the foundation is relatively soft and deep, analysis for foundation-soil interaction always must be peformed. To consider foundation-soil interaction, soil response analysis is preceded, and after determining the material characteristics of foundation element obtained by foundation-soil interaction analysis at the frequency domain, the seismic response analysis of bridge superstructure with the equivalent spring and damper is performed. Finally, influences of multi-support input motion, which are affected by different soil characteristics, are also considered in this paper.

• Journal of Korean Physical Therapy Science
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• v.9 no.3
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• pp.161-170
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• 2002

knee injuries are among the most common problems confronting patients, physical therapist and physicians. since the bony structure provides little stability, the soft tissues are required to withstand high forces, often resulting in tissue overload and injury immobilization of the knee in the presence of a hemarthrosis usually leads to proliferation of intraarticular connective tissue adhesions and pint fibrosis. the physical basis of treating scar tissue is early controlled motion. the management of the knee with increased instability is to strengthening the muscles to properly treat an soft tissue injuries, physical therapist should know about the anatomic structures and biomechanical function of the knee joint, in this review article, we discuss the physiologic properties of soft tissue, biomechanical observation in fibrous connective tissue, managing soft tissue contractures, principles in treating scar tissue and treatment of the knee with increased instability.

• Journal of the Korean Magnetics Society
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• v.4 no.1
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• pp.1-6
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• 1994

The magnetization dynamics was investigated by solving possible origins of overdamped susceptibility observed in ultra-soft magnetic amorphous thin films. The experimental high frequency spectrum and computational spectrum calculated from Gilbert's equation of motion were compared in order to find proper damping factor $\alpha{\approx}20$ and demagnetizing coefficients $D_{x}{\approx}D_{y}{\approx}D_{z}{\approx}0$ for ultra-soft magnetic films. A magnetization vortex mode was, then, proposed to explain the origin of the reversible susceptibility and other anomalies of the ultra-soft magnetic heterogeneous thin films. In this mode it is suggested that there occur, within the nanoscale structural features of the ultra-soft films, incoherent rotational spin motions that are highly damped by the energy transfer from short wavelength spin wave modes and local defect structure mode interactions.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.311-314
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• 2006

This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely soft cohesive soil is applied to the self-propelled miner. The hydrodynamic forces and moments are included in the dynamic models of vehicle and lifting pipe system. Hinged and fixed constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-b method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.69-74
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• 2005

This study was carried out to investigate experimentally the effect of the ground condition and tire inflation pressure on rolling characteristics of towed wheel, including the deformation, sinkage, effective rolling radius and motion resistance of tire. The experiment was performed at soil bin for the three levels of off-road conditions(ground-I, ground-II and ground-III) and a on-road condition(ground-IV), and for the four levels of tire inflation pressure which were 80 kPa, 160 kPa, 240 kPa and 320 kPa. The results of this study are summarized as follows: 1. As the tire inflation pressure of towed wheel increased, the tire deformation decreased exponentially, but the tire sinkage increased exponentially. This trend was getting bigger as ground condition was getting softer. 2. The increase of tire inflation pressure increased the effective rolling radius of towed wheel, and this kind of trend occurred greatly as ground condition was soft. As a result, the effective rolling radius for the off-road condition was always larger than that for on-road condition. 3. For the on-road condition, as the tire inflation pressure of towed wheel increased, the motion resistance decreased, but for the off-road condition, augmentation of tire inflation pressure increased the motion resistance. Also, the effect of inflation pressure on motion resistance appeared great as ground condition was soft. Therefore, in order to improve the tire performance by the control of inflation pressure, it is desirable to reduce the tire inflation pressure for off-road condition and to increase the tire inflation pressure for on-road condition.

• Structural Engineering and Mechanics
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• v.43 no.5
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• pp.637-655
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• 2012

In this study, stochastic responses of a cable-stayed bridge subjected to the spatially varying earthquake ground motion are investigated by the finite element method taking into account soil-structure interaction (SSI) effects. The considered bridge in the analysis is Quincy Bay-view Bridge built on the Mississippi River in between 1983-1987 in Illinois, USA. The bridge is composed of two H-shaped concrete towers, double plane fan type cables and a composite concrete-steel girder deck. In order to determine the stochastic response of the bridge, a two-dimensional lumped masses model is considered. Incoherence, wave-passage and site response effects are taken into account for the spatially varying earthquake ground motion. Depending on variation in the earthquake motion, the response values of the cable-stayed bridge supported on firm, medium and soft foundation soil are obtained, separately. The effects of SSI on the stochastic response of the cable-stayed bridge are also investigated including foundation as a rigidly capped vertical pile groups. In this approach, piles closely grouped together beneath the towers are viewed as a single equivalent upright beam. The soil-pile interaction is linearly idealized as an upright beam on Winkler foundation model which is commonly used to study the response of single piles. A sufficient number of springs on the beam should be used along the length of the piles. The springs near the surface are usually the most important to characterize the response of the piles surrounded by the soil; thus a closer spacing may be used in that region. However, in generally springs are evenly spaced at about half the diameter of the pile. The results of the stochastic analysis with and without the SSI are compared each other while the bridge is under the sway of the spatially varying earthquake ground motion. Specifically, in case of rigid towers and soft soil condition, it is pointed out that the SSI should be significantly taken into account for the design of such bridges.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2351-2369
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• 2012

This paper describes interpolation method of motion field in the Wyner-Ziv video coding (WZVC) based on Expectation-Maximization (EM) algorithm. In the EM algorithm, the estimated motion field distribution is calculated on a block-by-block basis. Each pixel in the block shares similar probability distribution, producing an undesired blocking artefact on the pixel-based motion field. The proposed interpolation techniques are Bicubic and Lanczos which successively use 16 and 32 neighborhood probability distributions of block-based motion field for one pixel in k-by-k block on pixel-based motion field. EM-based WZVC codec updates the estimated probability distribution on block-based motion field, and interpolates it to pixel resolution. This is required to generate higher-quality soft side information (SI) such that the decoding algorithm is able to make syndrome estimation more quickly. Our experiments showed that the proposed interpolation methods have the capability to reduce EM-based WZVC decoding complexity with small increment of bit rate.