• Journal of the Society of Naval Architects of Korea
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• v.50 no.1
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• pp.8-13
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• 2013

Excessive yaw motion of a turret moored vessel was examined in this paper. The vessel was moored by an internal turret and catenary mooring lines. The experiments were conducted in regular waves. Turret moored vessel can oscillate from side to side or move to one particular direction, and eventually exhibit large yaw motion. The results showed that the excessive yaw occured for specific condition, ratio of wave lengths and vessel length. It was found that turret moored floating vessel was unstable for regular wave period from 14 to 18 sec and excessive yaw occurred to maximum 50 deg. The time series, trajectory, phase plot and qualitative analysis are performed. The analysis showed that the results of experiments agreed with the that of analytic method and the excessive yaw could be predicted by the stability analysis.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.304-315
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• 2020

The main features of offshore turret platforms are station-keeping and weathervaning functions. Due to the complexity of the yaw motion, abundant research is being done to verify the factors that affect the heading stability. Simulations are used for studies that are not possible with experiments, but the conditions must be verified using experimental results. This study presents methods to estimate turret-related parameters such as the rotational stiffness and rotational damping. A time series analysis was performed, and the results showed that the calculation using the obtained parameters agreed well with experimental results.

• Journal of Ocean Engineering and Technology
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• v.29 no.2
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• pp.143-153
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• 2015

This paper presents the results of an experimental study on the motion of an FPSO (Floating production storage and off-loading) and the characteristics of the mooring systejavascript:confirm_mark('abe', '1');m according to the turret position. Model tests of a turret-moored FPSO were carried out in the Ocean Engineering basin of KRISO. The FPSO was moored using an internal turret and catenary mooring. The models (1/60 scale) that were prepared included the FPSO, turret, and mooring lines. The experiments were conducted in irregular waves and combined environments, with waves, currents, and winds. A time-domain simulation was performed using OrcaFlex. The motion response and mooring line tension from the present calculations were compared with the results of experiments, and the agreement was fairly good. In addition, the results showed that the weathervaning stability was improved when the position of the turret was moved in the bow direction.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.674-686
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• 2019

In this paper, we will discuss the absolute angular error control mode for the Gun/Turret driving system. The Gun/Turret driving controller receives absolute angular error calculated from the fire control system (FCS). Thus, the Gun/Turret driving controller is subjected to step command to cause residual vibration and system unstable. In order to reduce residual vibration and to ensure the system stability, we propose an error motion profile method with two types of trapezoidal and S-Curve. The validity of the proposed error motion profile method is confirmed via simulation by observing that the resulting position error, driving power, and power density satisfied the control performance.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.66-69
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• 1989

In this paper, the LQG/LTR design method is applied of the third order linear time invariant plant model which is the SISO turret-gun servo-mechanism. The dynamic characteristics and the performance of the LQG/LTR controller are analyzed by the computer simulation, and compared with those of PID controller which has been already applied to the turret servomechanism under the sane design specifications.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.160-163
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• 1988

In this paper, the adaptive controller for the turret gun is discussed which uses model reference adaptive technique based on the Lyapunov direct method. Turret gun can be decomposed into two time-invariant SISO control systems. One is for the elevation angle control and the other is for the azimuth angle control under the assumption of independence each other. Thus we only consider here about the control loop for the elevation angle.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.32-39
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• 2009

This paper describes mathematical models of the torsional geared driving system for the indexing path and the mill driving path in a mill turret. The eigenvalue analysis for the models is conducted both with and without the gear contact stiffnesses. The natural frequency leads to the effect of gear contact stiffnesses on the vibration of torsional geared systems in a mill turret. It is necessary to analyze eigenvalues of the complex geared torsional system in order to prevent the unexpected vibrations.

• The Journal of the Korean bone and joint tumor society
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• v.18 no.2
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• pp.109-112
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• 2012

A turret exostosis was known a smooth, dome-shaped extracortical collection of subperiosteal bone beneath the extensor apparatus. In most cases, turret exostosis involve middle and distal phalanges compared with involving metacarpal cases have been rarely reported in the literature.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.556-556
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• 2000

In the multi-purpose lathe, the design of tilting turret slide system has an important and critical role to enhance the accuracy of the machining process. Tilting turret unit is traveled by 3-axis slide systems. There is a need to design this part very carefully. In this research, the 3-axis slide system with tilting turret unit is researched with two approaches; The first is that 3-axis slide system is modeled and simulated using ADAMS software. The dynamic behavior of this system is visualized by data graphs and dynamic animations. The second is that the slide system is analyzed with the aspect of stress distribution. The slide system is modeled and displayed by PATRAN and analyzed by NASTRAN. The analysis of strain and stress distribution in the each node is prompted and visualized in the computer. The first step of virtual prototype which makes it possible to design economically and effectively is developed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.1
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• pp.49-54
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• 2005

Recently, the reliability are applied for many industrial products, and many products are required to guarantee in quality and in performance. The purpose of this paper is to present some of reliability prediction methodologies using failure rate database for machinery parts that are applicable to machine tools. VDI Turret, which is core component of the NC Lathe, was chosen as the target of the reliability prediction. The results of reliability prediction has shown the failure rate, MTBF(Mean Time Between Failure), and reliability of the VDI Turret. It is expected that proposed methodologies will be applicable to prediction of reliability for other components of machine tools.