• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.395-409
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• 2017

Objective: The purpose of this study was to optimize the number and positions of foot pressure sensors using the reliability analysis of the center of pressure (COP) in smart shoes. Background: Foot pressure can be different according to foot region, and it is important which region of the foot pressure needs to be measured. Method: Thirty adults (age: $20.5{\pm}1.8years$, body weight: $71.4{\pm}6.5kg$, height: $1.76{\pm}0.04m$) participated in this study. The foot pressure data were collected using the insole of Pedar-X system (Novel GmbH, USA) with a sampling frequency of 100Hz during 1.3m/s speed walking on the treadmill (Instrumented treadmill, Bertec, USA). The intraclass correlation coefficients (ICC) were calculated between the COP positions using 4, 5, 6, 7, 8, and 99 sensors, while one-way repeated measure ANOVA was performed between the standard deviation (SD) of the COP positions. Results: The medio-lateral (M/L) COP position using 99 sensors was positively correlated with the M/L COP positions using 6, 7, and 8 sensors; however, it was not correlated with the M/L COP positions using 4 and 5 sensors during landing phase (1~4%) (p<.05). The antero-posterior (A/P) COP position using 99 sensors was positively correlated with the A/P COP positions using 4, 5, 6, 7, and 8 sensors (p<.05). The SD of the COP position using 99 sensors was smaller than the SD of the M/L COP positions using 4, 5, 6, 7, and 8 sensors (p<.05). Conclusion: Based on our findings, it is desirable to arrange at least 6 sensors in smart shoes. Application: The study of optimizing the number and positions of foot pressure sensors would contribute to developing more effective smart shoes using foot pressure technology.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.1
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• pp.35-48
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• 1995

To develop the optimal design method for the longline type scallop culturing facilities in the open sea numerical calculations and hydraulic model experiments are carried out for the stability and function optimization. Using the results for the motion and tension of the facilities, stable design concepts and effects of motion control system by vertical anchor and resistance discs art discussed. The results of this study that can be applied to the design are as follows: 1) Total external forces by design wave $(H_{1/3}\;=\;6,7\;m,\;T_{1/3}\;=\;12sec)$ at the coastal waters of Jumunjin for unit facility (one main line) are estimated to 5-20 tons, and required anchor weights are 10-40 tons in the case of 2-point mooring system. Though the present facilities are stable to steady currents, but is unstable to the extreme wave condition of return period of 10 years. 2) The dimensions and depth of array systems must be designed considering the ecological environments as well as the physical characteristics including the mooring and holding forces that are proportional to the length and relative depth of main line to wave length, and the number of buoys and nets. 3) Oscillation of the facility is influenced by water particle motion and the weight of hanging net, and is excited at both edge, especially at the lee side. To reduce the motion of the nets, the vertical anchoring system and the resistence disc method are recommended by the experimental results, 4) The damage of rope near the anchor by abrasion should be prevented using the ring-type connection parts or anchor chains.

• Journal of Ocean Engineering and Technology
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• v.19 no.3
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• pp.66-73
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• 2005

The sway motion control problem of a container hanging on the trolley is considered in this paper. In the container crane control problem, the main issue involves suppressing the residual swing motion of the container at the end of acceleration, during deceleration, or for an unexpected disturbance input. For this problem, in general, many trolley motion control strategies are introduced and applied. In this paper, we introduce and synthesize a swing motion control system, in which a small auxiliary mass is installed on the spreader. In this control system, the actuator reacting against the auxiliary mass applies inertial control forces to the container to reduce the swing motion in the desired manner. In many studies, the controllers used to suppress the vibration have been synthesized for the given mathematical model of plants. In many cases, the designers have not been able to utilize the degree of freedom to adjust the structural parameters for the control object. To overcome this problem, so called "Structure/Control Simultaneous Method" is used. From this, in this paper the simultaneous design method is used to achieve optimal system performance. And the experimental result shows that the proposed control strategy is useful, to the case of that the controlled system is exposed to the uncertainties and, robust to disturbances like wind.

• Journal of KIISE:Software and Applications
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• v.31 no.2
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• pp.245-254
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• 2004

This paper deals with the problem of estimating structure and motion from long continuous image sequences, applying the Expectation Maximization algorithm based on extended Kalman smoother to impose the time-continuity of the motion parameters. By repeatedly estimating the state transition matrix of the dynamic equation and the parameters of noise processes in the dynamic and measurement equations, this optimization gives the maximum likelihood estimates of the motion and structure parameters. Practically, this research is essential for dealing with a long video-rate image sequence with partially unknown system equation and noise. The algorithm is implemented and tested for a real image sequence.

• International Journal of High-Rise Buildings
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• v.4 no.1
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• pp.1-8
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• 2015

A team of researchers and practitioners were recently assembled to prepare a monograph on "Wind-Induced Motion of Tall Buildings: Designing for Habitability". This monograph presents a state-of-the-art report of occupant response to wind-induced building motion and acceptability criteria for wind-excited tall buildings. It provides background information on a range of pertinent subjects, including: ${\bullet}$ Physiological, psychological and behavioural traits of occupant response to wind-induced building motion; ${\bullet}$ A summary of investigations and findings of human response to real and simulated building motions based on field studies and motion simulator experiments; ${\bullet}$ A review of serviceability criteria to assess the acceptability of wind-induced building motion adopted by international and country-based standards organizations; ${\bullet}$ General acceptance guidelines of occupant response to wind-induced building motion based on peak acceleration thresholds; and ${\bullet}$ Mitigation strategies to reduce wind-induced building motion through structural optimization, aerodynamic treatment and vibration dissipation/absorption. This monograph is to be published by the American Society of Civil Engineers (ASCE) and equips building owners and tall building design professionals with a better understanding of the complex nature of occupant response to and acceptability of wind-induced building motion. This paper is a brief summary of the works reported in the monograph.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.129-136
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• 2009

The estimation of muscle force is important to understand the roles of the muscles. The static optimization method can be used to figure out the individual muscle forces. However, muscle forces during the movement including muscle co-contraction cannot be considered by the static optimization. In this study, a hybrid static optimization method was introduced to find the well-matched muscle forces with EMG signals under muscle co-contraction conditions. To validate the developed algorithm, the 3D motion analysis and its corresponding inverse dynamics using the musculoskeletal modeling software (SIMM) were performed on heel-rise movements. Results showed that the developed algorithm could estimate the acceptable muscle forces during heel-rise movement. These results imply that a hybrid numerical approach is very useful to obtain the reasonable muscle forces under muscle co-contraction conditions.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.122-128
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• 2007

In this paper, a method of station keeping strategy using relative orbital motion and numerical optimization technique is presented for geostationary satellite. Relative position vector with respect to an ideal geostationary orbit is generated using high precision orbit propagation, and compressed in terms of polynomial and trigonometric function. Then, this relative orbit model is combined with optimization scheme to propose a very efficient and flexible method of station keeping planning. Proper selection of objective and constraint functions for optimization can yield a variety of station keeping methods improved over the classical ones. Nonlinear simulation results have been shown to support such concept.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5512-5526
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• 2019

In sports video games, especially ball games, motion capture techniques are used to reproduce the ball-driven performances. The amount of motion data needed to create different situations in which athletes exchange balls is bound to increase exponentially with resolution. This paper proposes how avatars in virtual worlds can not only imitate professional athletes in ball games, but also create and edit their actions effectively. First, various ball-handling movements are recorded using motion sensors. We do not really have to control an actual ball; imitating the motions is enough. Next, motion is created by specifying what to pass the ball through, and then making motion to handle the ball in front of the motion sensor. The ball's occupant then passes the ball to the user-specified target through a motion that imitates the user's, and the process is repeated. The method proposed can be used as a convenient user interface for motion based games for players who handle balls.

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.390-395
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• 2001

In this paper, we propose a fast warping prediction using bit-pattern for motion estimation. Because of the spatial dependency between motion vectors of neighboring node points carrying motion information, the optimization of motion search requires an iterative search. The computational load stemming from the iterative search is one of the major obstacles for practical usage of warping prediction. The motion estimation in the proposed algorithm measures whether the motion content of the area is or not, using bit-pattern. Warping prediction using the motion content of the area make the procedure of motion estimation efficient by eliminating an unnecessary searching. Experimental results show that the proposed algorithm can reduce more 75% iterative search while maintaining performances as close as the conventional warping prediction.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.35-42
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• 2000

The sway control problem of the pendulum motion of a container hanging on the trolly, which transports containers from a container ship to trucks, is considered in the paper. In the container crane control problem, suppressing the residual swing motion of the container at the end of acceleration or the case of that the unexpected disturbance input exists is main issue. For this problem, in general, the trolley motion control strategy is introduced and applied. But in this paper, we introduce and synthesize a new type of swing motion control system. In this control system, a small auxiliary mass is installed on the spreader. And the actuator reacts against the auxiliary mass, applying intertial control forces to the container to reduce the swing motion in the desired manner. In this paper, we apply the LMI approach and simultaneous optimization design method to design the anti-swing motion control system for the controlled plant. And the simulation result shows that the proposed control strategy is shown to be robust to disturbances like winds and initial sway motion.