• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.43-48
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• 2000

In this paper, an actively controlled anti-rolling system is considered to reduce the rolling motion of the ship. In this control system, a small auxiliary mass is installed on the upper area of the ship, and actuator us connected between the auxiliary mass and a ship. The actuator reacts against the auxiliary mass, applying inertial control forces to the ship to reduce the rolling motion in the desired manner. In this paper, we apply the PID controller to design the anti-rolling control system for the controlled ship. And the experimental result shows that the desirable control performance is achieved.

• Journal of the Korean Institute of Navigation
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• v.10 no.2
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• pp.139-155
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• 1986

In this paper the dynamic effects due to the free water motions in tanks upon the lateral motion of a floating body in regular waves are calculated, in order to obtain the relationship between a motion of a floating body and that of the free water in tanks. Under the assumption that the fluid is ideal and motion amplitudes are small, velocity potential of the fluid in tanks is calculated by the source distribution method and the hydrodynamic forces and moments are calculated by the integration of fluid pressures over the tank surface. Hydrodynamic effects of the fluid on the floating body are expressed in terms of added mass and coupling coefficient obtained from the integration. Computations are carried out for ship with seven wide center tanks and comparisons between the liquid cargo loading case and the rigid cargo loading case are shown.

• Structural Monitoring and Maintenance
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• v.6 no.4
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• pp.347-364
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• 2019

Two seismic response data from the CSMIP strong motion instrumentation of Pacoima dam are selected: San Fernando earthquake (Jan 13, 2001; ML=4.3) and Newhall earthquake (Sept. 1, 2011; ML=4.2), for the identification of the dam system. To consider the spatially nonuniform input ground motion along the dam abutment, the subspace identification technique with multiple-input and multiple-output is used to extract the dynamic behavior of the dam-reservoir interaction system. It is observed that the dam-reservoir interaction is significant from the identification of San Fernando earthquake data. The influence of added mass (from the reservoir) during strong ground motion will create a tuned-mass damper phenomenon on the dam body. The fundamental frequency of the dam will be tuned to two different frequencies but with the same mode shapes. As for the small earthquake event, the dam-reservoir interaction is insignificant.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.403-410
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• 2003

This paper presents the results of experimental studies on the equipment isolation effect in the nuclear containment. For this purpose, shaking table tests were performed. The isolation system, known as Friction Pendulum System (FPS), combines the concepts of sliding bearings and pendulum motion was selected. Peak ground acceleration, bidirectional motion, effect of vertical motion and frequency contents of selected earthquake motions were considered. Finally, it is presented that the FPS systems are effective for the small equipment isolation. Key word equipment isolation, nuclear containment, shaking table test, Friction Pendulum System (FPS)

• Bulletin of the Society of Naval Architects of Korea
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• v.11 no.1
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• pp.1-8
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• 1974

Hydrodynamic forces and moments produced by the swaying oscillation on the free surface were exactly calculated by Ursell-Tasai method for the cylinders with Kim's chine form sections and the sway responses of the cylinders of those chine form sections among the regular beam sea were also calculated. The results of the computation were compared with those of Lewis form sections. It is concluded that the effects of the section form on the added mass, and damping are small, if the section forms had same beam-draft ratio and sectional area coefficient in the case of sway motion. It is also known that the above little effects of section shapes on the basic hydrodynamic forces do not effect on the sway motion responses of cylinderical bodies among the regular beam sea. The sway motion responses of cylinderical bodies are varied linearly with the wave numbers.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.06a
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• pp.216-217
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• 2019

Light Field (LF) image can be understood as a set of images captured by a multi-view camera array at the same time. The changes among views can be modeled by a general motion model such as affine motion model. In this paper, we study the impact of affine coding tool of Versatile Video Coding (VVC) on LF image compression. Our experimental results show a small contribution by affine coding tool in overall LF image compression of roughly 0.2% - 0.4%.

• Advances in aircraft and spacecraft science
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• v.10 no.5
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• pp.473-494
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• 2023

This article introduces a formalism for the analysis of airplane trajectories on which the motion is determined by specifying the power of the engines. It explains a procedure to solve the equations of motion to obtain the value of the relevant flight parameters. It then enumerates the constraints that the dynamical abilities of the airplane impose on the amount of fuel used, the speed, the load factor, the lift coefficient, the positivity and upper boundedness of the power available. Examples of analysis are provided to illustrate the method proposed, with rectilinear and circular trajectories. Two very different types of airplanes are used in the examples: a Silver Fox-like small UAV and a common Cessna 182 Skylane.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1961-1965
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• 2003

The flow analysis is needed to verify the physical phenomena through interruption processes for improving the capacity and the reliability of gas circuit breakers. Moreover the small current interruption performance of GCBs could be predicted by coupling the flow characteristics with the electric field one. In this paper, the unsteady flow characteristics and the traveling trajectory are depicted with a commercial CFD code, PHOENICS, programmed for moving motion of objects. In order to validate computational results, the measured pressure data in cylinder and in front of arcing contact are compared with the test results of small current interruption.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.813-819
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• 2006

The state of the art for the design of swing ann actuators for optical disc drives is to obtain the high efficient dynamic characteristics, especially for the small size for the mobile information devices, It is affected by the need of consumers who wants the portable digital storage devices maintaining highly functional and removable characteristics of the optical disk drive (ODD). As a necessary consequence, the need of the small form factor (SFF) storage device has been considered as an important part in the information storage technology. In this paper. we suggest a new conceptual miniaturized swing arm type actuator that has high efficient dynamic characteristics as well as satisfies the sensitivity and the heat emission requirements for the SFF-ODD. It also uses a tracking electromagnetic (EM) circuit for a focusing motion. Due to the size constraint, the thermal problem of optical head arises; therefore, we design an efficiently heat emitted structure for the actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.357-362
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• 2000

Though there have been many researches to investigate the relationship between the damage location, damage size and the changes in eigenparameters, there have been few studies on the small-sized damages. Thus, this paper considers the plate with small local damages. The equation of motion for damaged plate is derived in terms of the damage distribution function and then the effects of small damages on the dynamic characteristics of plate are investigated. It is observed that the damage-induced modal coupling and a sufficient number of vibration modes should be considered especially for small damage detections.