• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.376-381
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• 2009

The increasing needs for higher cargo capacity in the container vessels' fleet has led to ship builder's demand for higher power output rating engine to meet the propulsion requirement, thus, leading to the development of super large two stroke low speed diesel engines. This large sized bore engines with more than 12 cylinders are capable of delivering power output up to more than 100,000 bhp at maximum continuous rating. The thrust variation force due to axial vibration occurring in propulsion shafting of these ships are transmitted to ship structure via thrust bearing. This force may vibrate the super structure of ship in the fore-aft direction and the fatigue strength of crank shaft can be decreased by additional bending stress increase in crank shaft pin and journal. In this paper, the axial vibration of propulsion shafting system on the 14RT-flex96C super large diesel engine with 14 cylinders is identified by theoretical analysis and vibration measurement.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.895-902
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• 2015

In this paper, finite element analysis of a cycloidal pitch reducer for a 2 MW-class wind turbine is reviewed. The system is composed of one cycloid set, one spur gear set, an input shaft, an output shaft, and a housing. The system was also evaluated for stability by analyzing spur gear strength according to ISO 6336. An analysis of the natural vibration characteristics of the 2 MW-class wind turbine cycloid pitch reducer was performed with attention to critical speed with input mass unbalance, output mass unbalance, spur gear transmission error, cycloid gear transmission error, and excitation frequency.

• Journal of Wind Energy
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• v.15 no.1
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• pp.43-49
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• 2024

This study performed a response analysis according to the transmission error of the yaw drive. To perform the response analysis, the excitation source of the transmission error was modeled and the outer ring of the first stage bearing and the outer ring of the output shaft bearing were used as measurement positions. The response results were analyzed based on the vibration tolerance values of AGMA 6000-B96. As a result of the response of the first stage bearing outer ring, the maximum displacement of the first stage planetary gear system was 5.59 and the maximum displacement of the second to fourth stage planetary gear systems was 4.21 ㎛ , 3.13 ㎛ , and 25.6 ㎛ . In the case of the output shaft bearing outer ring, the maximum displacement of the first stage planetary gear system was 1.73 ㎛, and the maximum displacement of the second to fourth stage planetary gear system was 1.94 ㎛, 0.73 ㎛, and 2.03 ㎛. According to AGMA 6000-B96, the vibration tolerance of first stage is 17.5 ㎛, and the vibration tolerance of the second to fourth stages is 58 ㎛, 80 ㎛, and 375 ㎛, which shows that the vibration tolerance is satisfied and it is safe.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.45-54
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• 2019

In this study, we analyze the rattle noise of a power takeoff (PTO) driveline and develop a PTO driveline resonance model. We measured the rattle noise of the PTO driveline on the output shaft and, by analyzing the rattle noise in the time domain, we determine that the engine expansion stroke period matches the sound pressure of rattle noise. This finding helped us demonstrate that the rattle noise is caused by the collision between the PTO driving gear and the gear driven by the engine expansion stroke; the torsional vibration caused by this collision is affected by the angular velocity fluctuation of the PTO drive shaft. By measuring the angular velocity of the PTO drive shaft, we confirm that the angular velocity fluctuation of the engine flywheel tends to excessively amplify the PTO drive shaft angular velocity fluctuation. We conclude that the resonance, which occurs when the operating frequency of the engine is close to the natural frequency of the tractor power transmission system, causes the excessive angular velocity fluctuation of the PTO drive shaft. We performed a modal analysis of the PTO driveline resonance and, using the characteristic equation, we show that the resonance occurs when the engine rotation speed is close to 850 rpm, which matches the natural frequency of the PTO driveline.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.63-70
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• 2023

In this work, a capacitive wireless power transfer (C-WPT) system is presented for wireless sensor system (WSS) applications in marine propulsion shafts. For a single Q factor on both sides of the coupling capacitor and reactive power removal from the circuit, a double-sided LCLC converter and transformers topology are designed to drive the rotary C-WPT system for WSS on the shaft. Parallel-connected parallel plate rotating capacitors with a capacitance of 170 pF are designed and implemented for the C-WPT system on a snow rotating shaft. In the experimental results, the C-WPT system achieved a transmission efficiency of 66.67% with 7.8 W output power at 3 mm distance and 1 MHz operating frequency. Therefore, it was proved that the fabricated C-WPT system can supply power to the WSS of the rotating shaft.

• Applied Science and Convergence Technology
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• v.24 no.2
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• pp.27-32
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• 2015

We analyzed the destruction patterns of a turbo-molecular pump (TMP) resulting from its sudden exposure of a foreline to the atmospheric pressure due to a destruction of the foreline connecting clamp of an ICP dry etcher for 300 mm wafers during high-vacuum operation ($5{\times}10^{-6}$ Torr). Unlike in the case of view port's breakage, the TMP's rotor module was crashed inside the chamber. The primary damage resulted from the collision of the blades and stators, and the secondary damage resulted from the breaking of the rotor - driving shaft assembly. The fixing screws of the rotor and axial shaft were bent and broken when the TMP controller output the maximum current even after the crash event. Electrical power consumption analysis of the TMP power controller confirmed it. The stress distributions were analyzed by a finite element method using CFD-ACE+ multi physics software. Rotating inertia of each parts and kinetic energies were calculated as well. 68% of the rotational kinetic energy is deposited by the rotor - shaft module.

• Plant Journal
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• v.4 no.4
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• pp.56-61
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• 2008

The phenomena of oil whip in steam turbines take place for the unbalance force between a rotor shaft and bearing oil film. The several parameters that affect onset of oil whip have been well known. However, the major parameter of oil whip is shaft mis-alinement. A oil whip causes the high vibration and the shutdown of rotor system. We mostly stop the steam turbine to adjust a shaft re-alinement concerning oil whip. In this case, it needs many costs for maintenance and long shutdown times. In this study, we study and observe the oil whip of the 300MW steam turbine in many years and we conduct the field test for another steam turbine for reducing vibration from oil whip. The results of this study are that a oil whip takes place with a particular rotating speed or a particular turbine output and the oil temperature change is a very effective method for on-line oil whip treatment.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.1
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• pp.112-121
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• 2015

In this paper, powertrain of output split type plug-in hybrid electric vehicle is analyzed for the operation range of speed, torque, and power. First, it is assumed that the efficiency of motor is 100%. And, the speed and torque equations are derived based on the lever analogy. With the above equations, the simulations are performed for the powertrain of output split type plug-in hybrid electric vehicle. From the simulation results, it is found that the output torques of EV1 and series modes are larger than the EV2 and power split modes' ones. It means the EV1 and series modes can be used for the rapid acceleration. But the EV1 and series modes can be used only the velocity of under the 120 km/h. It is because the motor reaches its maximum speed when the velocity is over the 120 km/h for the EV1 and series modes. When the engine is turned on, the engine power is transmitted through the two motors. But, the power split mode shows the power split of engine at the output shaft, and it has the point of zero motor power. Thus, the transmission efficiency of the power split mode can be higher than the series mode's one, it the motor efficiency is considered.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.1
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• pp.46-52
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• 2012

Since the engine and reduction gear in a naval vessel are usually supported by the mounting system separately, the misalignment between the input shaft of the reduction gear and the output shaft of the engine should occur caused by ship motion. In this study, this misalignment is estimated from the linear static analysis assuming that the phase of movements of the engine and reduction gear at low frequency range is same and the dynamic effect is not affect to them. Through comparing the relative displacement of the engine and reduction gear calculated from linear static analysis to that from dynamic analysis as well as experiment, the assumption in this study could be verified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1262-1265
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• 2004

A cycloidal speed reducer is a type of the speed reducers of machinery. The cycloidal speed reducer consists of two cycloidal plate gears, housing roller gear, input shaft, output pin and shaft, and eccentric bearings. Especially the cycloidal plate gear has the peculiar parts of the teeth, because of gearing with the housing roller gear that has the several rollers on the circular line. And then all teeth on the cycloidal plate gear can be designed to contact with the rollers on the housing roller gear at the same time. Therefore the cycloidal plate gear has always contact motion with rollers and the force is interacted between roller gear with cycloidal plate gear. Because the contact force and friction force must be required to improve the accuracy in design procedures of cycloidal speed reducers, this paper presents a force analysis considered friction effect approach derived by static force equilibrium condition, geometrical adaptation, instant velocity center method and relative velocity method.