• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.7
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• pp.904-914
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• 2004

In this paper, input-output velocity and force transmission characteristics of the Casing Oscillator which is a construction machine with 4 degrees of freedom are examined. After the Jacobian matrix is decomposed into the linear part and angular part, the velocity and force transmission characteristics for the linear and angular workspace are easily analyzed and visualized even if the Casing Oscillator has the spatial dimensional workspace with 4 DOF. Regarding the manipulability measure of the Casing Oscillator, the kinematic isotropic index and the manipulability measure which represent the isotropy and volume of the manipulability ellipsoid, respectively, are combined to coincidently consider them with respect to equivalent ranges and fluctuations. A performance of the Casing Oscillator is evaluated by the newly proposed manipulability measures.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.760-769
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• 2006

This paper proposes an autopilot system using a fuzzy PID controller to satisfy performances required for the automatic navigation of ships under various marine circumstances. The existing autopilot system using a PD type controller has difficulties in eliminating a steady-state error and compensating nonlinear characteristics of ships. The autopilot system using the proposed fuzzy PID controller has a self-tuning ability, an ability to compensate nonlinear characteristics, and an ability to turn at constant angular velocity. Therefore. it can naturally make a steady-state error zero, compensate nonlinear dynamic effect of ships, have an adaptability to parameter variation owing to shallow water effect, and have an ability to turn ship's course rapidly without overshoot through procedures of acceleration, constant, and deceleration of angular velocity for large course-changing.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.7
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• pp.623-631
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• 2000

Effects of the taper angle and the angular velocity of a pulse tube on the enthalpy flow loss associated with the steady mass streaming were analysis by two-dimensional analysis of a pulse tube with variable cross-section. It was shown that the steady mass flux can lead to a large steady second-order temperature. The enthalpy flow loss associated with the steady mass streaming increases as the angular velocity increases. For a pulse tube where the viscous penetration depth is far thinner than the inner radius, the enthalpy flow loss can be significantly reduced by tapering the pulse tube since both the steady mass flux and the steady second-order temperature decrease as the taper angle increase.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.7 s.100
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• pp.865-870
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• 2005

Torque fluctuation of the engine and angular velocity variation of propeller shaft is the main excitation source for torsional vibration in the vehicle driveline. Experimental model for engine system is constructed with 4 cylinder 4 cycle diesel engine including Motor-Propeller Shaft-Axle-Wheel system. The angular velocity is measured by magnetic pickup and FV converter at the engine flywheel and propeller shaft. This paper presents the theoretical mechanism of these excitation sources and it is identified by the experimental methods.

• Journal of KSNVE
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• v.9 no.3
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• pp.461-465
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• 1999

This paper presents theoretical analyses for unstable vibrations caused by the couple of bending and torsion in a rotating shaft driven through a universal joint. A driving shaft is assumed to be rigid and to rotate with a constant angular velocity. The driven shaft system consists of a flexible shaft with a circular section and a symmetrical rotor attached at a point between the shaft ends. Equations of motion derived hold with an accuracy of the second order of shaft deformations, and are analyzed by the asymptotic method. The vibrations become unstable when the driving shaft rotates with the angular velocity to be approximately equal to half of the sum of the natural frequencies for whirling and torsional vibrations.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.111-114
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• 1999

The twisting and extrusion process of the product with involute helical fin from the round billet is developed by the upper bound analysis. The twisting of extruded product is caused by the twisted die surface connecting the die entrance section and the die exit section linearly. In the analysis, the internal shear surface is defined as the curved twisted plane from the taisting of die surface and the shear work is calculated by the consumption of shear energy The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product increases with the die twisting angle, the reduction of area, and decreases with the die length, the friction condition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.4
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• pp.129-134
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• 2005

A numerical analysis was performed on magnetic field effects of silicon melt motion in Czochralski crystal puller. The turbulent modeling was used to simulate the transport phenomena in 18' single crystal growing process. For small crucible angular velocity, the natural convection is dominant. As the crucible angular velocity is increased, the forced convection is increased and the distribution of temperature profiles is broadened. The cusp magnetic field reduces effectively the natural and forced convection near the crucible and the temperature profiles of the silicon fluids is similar in the case of conduction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1017-1022
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• 1996

This paper presents results of dynamic analysis of the missile initial motion arising from the missile detent force. Using ADAMS (Automatic Dynamic Analysis of Mechanical System) software, a non-linear 46-DOF (Degree of Freedom) model is developed for the launcher system including missile and launch tube contact problem. From the dynamic analysis, it is found that initial angular velocity of the missile increases when the missile detent force increases (more than 18 g) and also rocket exhaust plume is taken into account. To achieve the missile launching s ability, it needs to reduce the missile initial detent force and exhaust plume area of the launcher. Results of the dynamic analysis on the system natural frequency agree well with those obtained from experimental modal tests. The overall results suggest that the proposed method is a useful tool for prediction of initial missile stability as well as d :sign of the missile launcher system.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.177-181
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• 2005

Fishing selectivity is determined by the level of voluntary escaping behavior in accordance with decision-making based on the relationship between fish size and mesh size. This study examined movement during the swimming behavior of black porgy in a trawl's towing cod-end and analyzed the movement components such as swimming speed, angular velocity of turning, and distance to the net over time. Most of the observed fish exhibited an optomotor response, maintaining position and swimming speed without changing direction. Others exhibited erratic or 'panic' behavior with sudden changes in swimming speed and direction. The latter behavior involved very irregular and aperiodic variations in swimming speed and angular velocity, termed 'chaotic behavior.' Thus, the results of this study can be applied to a chaotic behavior model as a time series of swimming movements in the towing cod-end for the fishing selectivity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.3
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• pp.413-422
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• 1996

Freezing of water in von-$K{\acute{a}}rm{\acute{a}}n$ swirling flow is considered. The transient behavior of the temperature distribution in both solid and liquid phases and freezing rate are determined. The fluid flow induced by the rotation of solid strongly inhibits the freezing process. The thickness of frozen layer is inversely proportional to the square root of the angular velocity of solid. As the angular velocity or initial liquid temperature becomes larger, the freezing process is more strongly inhibited by the fluid flow. When phase change is present, the transient heat transfer rate is greater than the case with no phase change.