• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.235-240
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• 2001

A four degrees of freedom (dof) motion platform for bicycle simulator is developed. The motion platform, capable of the vertical linear and three angular motions, is designed based on analysis of the typical motion characteristics revealed by the existing six dof bicycle simulator. The platform essentially consists of two parts： the three dof parallel manipulator, consisting of a moving platform, a fixed base and three actuators, and the turntable to generate the yaw motion. The nonlinear kinematics and dynamics of the three dof parallel manipulator with multiple closed loop chains are analyzed for tracking control of the motion platform. The tracking performances of the three control schemes are experimentally compared： the computed torque method (CTM), the sliding mode control (SMC) and the PD control. The CTM and SMC, incorporated with the system dynamics model, are found to be equally better in performance than the PD controller, irrespective of the presence of external disturbance.

• Smart Structures and Systems
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• v.26 no.2
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• pp.195-211
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• 2020

Among anti-seismic technologies, base isolation is a very effective means of mitigating damage to structural and nonstructural components, such as equipment. However, most seismic isolation systems are designed for mitigating only horizontal seismic responses because the realization of a vertical isolation system (VIS) is difficult. The difficulty is primarily due to conflicting isolation stiffness demands in the static and dynamic states for a VIS, which requires sufficient rigidity to support the self-weight of the isolated object in the static state, but sufficient flexibility to lengthen the isolation period and uncouple the ground motion in the dynamic state. To overcome this problem, a semi-active VIS, called the piezoelectric inertia-type vertical isolation system (PIVIS), is proposed in this study. PIVIS is composed of a piezoelectric friction damper (PFD) and a leverage mechanism with a counterweight. The counterweight provides an uplifting force in the static state and an extra inertial force in the dynamic state; therefore, the effective vertical stiffness of PIVIS is higher in the static state and lower in the dynamic state. The PFD provides a controllable friction force for PIVIS to further prevent its excessive displacement. For experimental verification, a shaking table test was conducted on a prototype PIVIS controlled by a simple controller. The experimental results well agree with the theoretical results. To further investigate the isolation performance of PIVIS, the seismic responses of PIVIS were simulated numerically by considering 14 vertical ground motions with different characteristics. The responses of PIVIS were compared with those of a traditional VIS and a passive system (PIVIS without control). The numerical results demonstrate that compared with the traditional and passive systems, PIVIS can effectively suppress isolation displacement in all kinds of earthquake with various peak ground accelerations and frequency content while maintaining its isolation efficiency. The proposed system is particularly effective for near-fault earthquakes with long-period components, for which it prevents resonant-like motion.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.173-178
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• 2015

In these days, the world has been increasing the development of various underwater vehicles such as ROVs (Remotely operated underwater vehicles) and AUVs (Autonomous underwater vehicles). And the importance of submarine's maneuverability is especially being emphasized. Therefore, accurate values of the derivatives in equations of motion are required to control motion of the submarines. The aims of the present study are to experimentally derive Hydrodynamic derivatives derived by the vertical planar motion mechanism (VPMM) model test, and to estimate vertical dynamic stability was estimated by using the linear hydrodynamic derivatives, the hydrodynamic derivatives of the submarine, which have a high propriety, were provided by using the fourier analysis of measured forces and moments. Furthermore it is confirmed that the experimental derivatives shows well agreement with the theoretical estimations, and the dynamic stability of the submarine was estimated as a good state, which implies that the value is greater than zero.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.20 no.2
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• pp.126-130
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• 2009

Arytenoid motion has long been recognized as complex. Misunderstandings about the specifics of arytenoid motion remain prevalent. The resultant misunderstandings have led to erroneous or suboptimal clinical approaches to the treatment of vocal fold immobility. A thorough understanding of the anatomy of the arytenoid and cricoid cartilages, the cricoarytenoid joint, and related ligaments, muscles, and other structures is essential in order to fully understand laryngeal motion disorders. Arytenoid motion occurs in three directions. Movements involving a change anteriorly and posteriorly, as well as vertically, are due to the revolving or pitchlike motion of the arytenoid along the minor axis of the cricoid's elliptically shaped facet. The medial and lateral movements are due to the orientation of the arytenoid which in turn is determined by the forward, lateral, and inferior inclination of the cricoid-arytenoid facet. During adduction it is the outward angulation of the vocal process from the body of the arytenoid that allows the entire length of the vocal proceses to approximate one another and to have this meeting occur at the proper vertical height.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.41-49
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• 2007

This study was to investigate the kinematical analysis using ski simulator. Twelve people(six skilled, six unskilled) participated in the experiment. Each phase of motion time was slight differences between the skilled group and the unskilled group but not significant difference in statistics. In displacement of vertical on COG(Center of Gravity), left and right down motion showed significant difference between group. In velocity of horizontal on COG, both left and right down motion showed significant difference between group, and up motion of between down motion showed significant difference. In displacement of angle on ankle, knee, hip joint almost showed significant difference between group. Almost in body position was lower skilled group than unskilled group.

• 한국기계연구소 소보
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• s.14
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• pp.17-31
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• 1985

The Primary object of this study is to predict rigid carbody's vertical and pitch acceleration and/or displacement frequency response to vertical sinusoidal rail surface irregularities for any specified point of the carbody, and to verify the predictions by means of experiments. The developed computer program also calculates vertical and pith transmissibilities and acceleration spectra. This model can be used for first order analysis of ride behabior. it's main advantage is its simplicity and ease of use. This model can be used for first order analysis of ride quality behabior. It's main advantage is its simplicity and ease of use. The model was designed with 6 degreed of freedom. Equations of motion were derived by Lagrangian method. This calculation was applied to the vertical dynamic analysis in order to pursue a possible improvement of the dynamic performance of co-co locomotive, and results were very useful.

• 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.

• Earthquakes and Structures
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• v.8 no.6
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• pp.1363-1386
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• 2015

The October 23 2011 Van Earthquake is studied from an earthquake engineering point of view. Strong ground motion processing was performed to investigate features of the earthquake source, forward directivity effects during the rupture process as well as local site effects. Strong motion characteristics were investigated in terms of peak ground motion and spectral acceleration values. Directiviy effects were discussed in detail via elastic response spectra and wide band spectograms to see the high frequency energy distributions. Source parameters and slip distribution results of the earthquake which had been proposed by different researchers were summarized. Influence of the source parameters on structural response were shown by comparing elastic response spectra of Muradiye synthetic records which were performed by broadband strong motion simulations of the earthquake. It has been emphasized that characteristics of the earthquake rupture dynamics and their effects on structural design might be investigated from a multidisciplinary point of view. Seismotectonic calculations (e.g., slip pattern, rupture velocity) may be extended relating different engineering parameters (e.g., interstorey drifts, spectral accelerations) across different disciplines while using code based seismic design approaches. Current state of the art building codes still far from fully reflecting earthquake source related parameters into design rules. Some of those deficiencies and recent efforts to overcome these problems were also mentioned. Next generation ground motion prediction equations (GMPEs) may be incorporated with certain site categories for site effects. Likewise in the 2011 Van Earthquake, Reverse/Oblique earthquakes indicate that GMPEs need to be feasible to a wider range of magnitudes and distances in engineering practice. Due to the reverse faulting with large slip and dip angles, vertical displacements along with directivity and fault normal effects might significantly affect the engineering structures. Main reason of excessive damage in the town of Erciş can be attributed to these factors. Such effects should be considered in advance through the establishment of vertical design spectra and effects might be incorporated in the available GMPEs.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.6
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• pp.102-111
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• 2009

In this paper, we propose a de-interlacing algorithm that combines a motion compensation (MC) method and the vertical-temporal filter with motion compensation (MC V-T filter) according to motion compensation reliability. The MC method represent one of the best ways of improving the resolution of de-interlaced frames, but it may introduce motion compensation artifacts in regions with incorrect motion information. In these regions, the MC V-T filter that is very robust to motion vector errors can be used to correct motion compensation artifacts. The combination between two methods is controlled by the motion compensation reliability that is measured by analyzing the estimated motion vectors and the results of MC. The motion compensation reliability contains information about motion compensation artifacts of MC results and determines the combination weight according to this information. Therefore, the combination rule of the proposed method is more accurate than those of the conventional methods and it enables the proposed method to provide high quality video sequences without producing any visible artifacts. Experimental results with various test sequences show that the proposed algorithm outperforms conventional algorithms in terms of both visual and numerical criteria.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.166-172
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• 2004

An underwater motion measurement system was constructed for applications to the model basin. A commercial motion capture system, FALCON of Motion Analysis Corp., which corrects automatically the distortion caused by refraction of the light passing through water and air, was adopted for underwater motion measurement. The modifications of FALCON system were performed: waterproofing camera housings, markers, connectors, and a new blue ring lighter. the accuracy of the motion measurement was obtained within the calibration error of 0.87mm in average and 0.89mm in standard deviation for the distance of 500mm between two markers on the calibration device. the volume of $2100mm(length)\times2100mm(breadth)\times2300mm(Height)$ was covered with 4 cameras of the underwater motion measurement system. For the performance verification, motion measurement test of a vertical mooring chain model excited at the top end was carried out. The 3D motions of mooring model were measured with variable amplitude and period of the forced excitation. Higher order motions of the mooring model were observed as the excitation period decreases. the performance of the system was verified by successfully measuring 3D motion of mooring model.