• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.10a
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• pp.239-240
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• 2009

Vessels stability problems need to resolve the nonlinear mathematical models of rolling motion. For nonlinear systems subjected to random excitations, there are very few special cases can obtain the exact solutions. In this paper, the specific differential equations of rolling motion for intact ship considering the restoring and damping moment have researched firstly. Then the partial stochastic linearization method is applied to study the response statistics of nonlinear ship rolling motion in beam seas. The ship rolling nonlinear stochastic differential equation is then solved approximately by keeping the equivalent damping coefficient as a parameter and nonlinear response of the ship is determined in the frequency domain by a linear analysis method finally.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.361-368
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• 2016

A ship's rolling motion can make crew and passengers sick and/or apply forces to the structure that cause damage.. Therefore bilge keels are equipped in most ships for anti-rolling. In special cases, anti-rolling tanks (ARTs), fin stabilizers, or gyroscopes can be installed. However, ARTs require a large area to install, and fin stabilizers and gyroscopes are costly to install and expensive to operate. This paper suggests a Anti-rolling pendulum (ARP) to reduce roll motion. ARPs acts like ARTs. However, the ARP has a circular shaped guidance arc instead of the string or wire of a simple pendulum. The device suggested has about 1/ 8 the weight and 1/ 6 the volume of a ART and is more effective. This study derives the nonlinear and linear differential equations of system motion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.176-187
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• 2005

This paper presents an evaluation of joint configurations of a robotic finger based on kinematic analysis. The evaluation is based on an assumption that the current control methods for the fingers require that the contact state specified by the motion planner be maintained during manipulation. Various finger-joint configurations have been evaluated for different contact motions. In the kinematic analysis, the surface of the manipulated object was represented by B-spline surface and the surface of the finger was represented by cylinders and a half ellipsoid. Three types of contact motion, namely, 1) pure rolling, 2) twist-roiling, and 3) slide-twist-rolling are assumed in this analysis. The finger-joint configuration best suited for manipulative motion is determined by the dimension of manipulation workspace. The evaluation has shown that the human-like fingers are suitable for maintaining twist-rolling and slide-twist-rolling but not for pure rolling. A finger with roll joint at its fingertip link, which is different from human fingers, proved to be better for pure rolling motion because it can accommodate sideway motions of the object. Several kinds of useful finger-joint configurations suited for manipulating objects by fingertip surface are proposed.

• Journal of Ocean Engineering and Technology
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• v.6 no.2
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• pp.41-45
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• 1992

In this paper an application technique of moment equation method to solution of nonlinear rolling equation of motion of ships is investigated. The exciting moment in the equation of rolling motion of ships is described as non-white noise. This non-white exciting moment is generated through use of a shaping filter. These coupled equations are used to generate moment equations. The nonstationary responses of the nonlinear system are obtained. The results are compared with those of a linear system.

• 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.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.459-464
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• 2003

The inner liquid pressure of an airtight tank in rolling motions is investigated by means of forced oscillation tests, and the simple method to estimate the inner liquid pressure is proposed. A rectangular solid tank, which is fully filled with water, was used in the forced oscillation test of rolling motion. The inner pressure variations in time were measured at several points on the inner walls of tank. Measured pressures are compared with the calculated ones, and estimation methods of the inner liquid pressure of the tank in rolling motion are studied based on the considerations of the origin of pressure.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.642-647
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• 2011

The fabrication characteristics of porous uranium oxide granules from $U_3O_8$ powder was investigated in terms of initial particle bed motions such as slumping and rolling, thermal treatment conditions, and rotational velocities in slumping motion using a rotary voloxidizer. With respect to the initial particle bed motion the recovery rate of granule of above 1 mm in slumping motion was higher than that in the rolling motion. Rolling motion was changed into slumping motion with high slumping frequency by formation of granules from fine particles. Recovery rate of granule significantly increased with the increas in thermal treatment temperature and time of upto 10 h. As the rotational velocity of voloxidizer in the case of the initial particle bed showing slumping motion increased, the recovery rate of granule increased from 81.5 to 88.7%. However, the rotational velocity of 2 rpm provided an effective density, crushing strength and sphericity of granules.

• Journal of Yeungnam Medical Science
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• v.7 no.2
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• pp.103-108
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• 1990

A method to roll-over the paralyzed body by means of Functional Electrical Stimulation(FES) is considered. It is demonstrated that individual joint motions necessary for the rolling-over are realized by electrical stimulation. EMG measurements are also performed to analyze the cooperative activities of the muscles during rolling over motion in a case where an upper extremity was used. These results of two experiments using normal subjects verifies the fundamental feasibility of body control by FES.

• Ocean Systems Engineering
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• v.1 no.3
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• pp.249-261
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• 2011

The stochastic nonlinear dynamic behavior and probability density function of ship rolling are studied using the nonlinear dynamical systems approach and probability theory. The probability density function of the rolling response is evaluated through solving the Fokker Planck Equation using the path integral method based on a Gauss-Legendre interpolation scheme. The time-dependent probability of ship rolling restricted to within the safe domain is provided and capsizing is investigated from the probability point of view. The random differential equation of ships' rolling motion is established considering the nonlinear damping, nonlinear restoring moment, white noise and colored noise wave excitation.

• Journal of the Korean Institute of Navigation
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• v.13 no.2
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• pp.23-36
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• 1989

Marine casualities in the high sea are mainly classified into the breakage of hull and capsize , of which the latter occurs frequently to a small craft and container vessels by extreme rolling. The aim of this study is to develop shiphandling techniques for the prevention of ship's large rolling by way of evaluating dangerous degree of rolling in heavy weather. In this study, rolling motion is analized by using statistical method as follow : (1) 8 sample ships is presented for calculation. (2) Analized sea state are Beaufort scale 7 and 10 (wind velocity 30kts and 50kts respectively) and significant wave height is put as 5.2m and 11.2m. (3) The formula recommended by International Towing Tank Conference (ITTC) is used to calculated the wave spectrum. The results of this study are as follow : The results of this study are as follow : (1) Most of the vessels with beam of 20 meters or less was found to be capized in the waves abeam under the sea condition of Bearfort scale7(30kts). (2) For the vessels range 20m to 30m was found safe under the sea conditions of Bearfort scale 7(30kts) and imminent danger under the sea condition of Beaufort scale 11(50kts). (3) It is proved that any vessel could be capsized by heavy rolling regardless of vessel's size whenever the motion is synchronized with waves abeam. This study concludes that the navigator, especially at night , must anticipate the exact wave direction, referring to the wether report and coastaline, not to lay the vessel in the serial wave abeam.