• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1441-1446
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• 2012

An axial-piston-type hydraulic motor involves friction and leakage losses at the sliding parts, contact loss at the mechanism assembly parts, volumetric loss caused by the pressure drop, housing oil churning loss and compressibility from the hydraulic oil pipe resistance, etc. the friction and volumetric loss at the hydrostatic bearing between the piston shoe and the swash plate rotating at high speed and having an oil film gap of 8-15 ${\mu}m$ strongly affects the total efficiency of the hydraulic motor. In this study, a variable swash-plate-type hydraulic piston motor operating under a maximum pressure of 35 MPa, maximum speed of 2,500 rpm, and displacement of 320 cc/rev is tested to verify the optimal ratio of the hydrostatic bearing which is closely related to the hydraulic motor performance.

• Journal of Navigation and Port Research
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• v.34 no.5
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• pp.311-317
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• 2010

Mobile Harbor(MH) is a new paradigm for maritime transport system introduced in Korea, the target of which is to carry out ship-to-ship cargo operation rapidly and effectively even under a condition of sea state 3. A MH ship is moored alongside a large container vessel anchored at the defined anchorage and also equipped with gantry cranes for handling containers. The MH study concerned includes rapid container handling system, optimum design for floating structure, hybrid berthing & cargo operation system, design for cargo handling crane, etc. This paper is to deal with a conceptual design of a stabilized mooring system and mooring equipment under a condition of ship-to-ship mooring. In this connection, we suggest a positioning control winch system in order to control heave motions of the MH ship which is to add constant brakepower and stabilized function to an auto-tension winch and mooring equipment used currently in large container ships.

• Journal of Advanced Navigation Technology
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• v.23 no.3
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• pp.245-250
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• 2019

Inertial navigation system has navigation errors because of the error of inertial measurement unit (IMU) and misalignment over time. In order to solve this problem, aided navigation system is performed using global navigation satellite system (GNSS), speedometer, etc. The inertial navigation system equipped with underwater vehicle mainly uses speedometer and performed aided navigation because satellite signals do not pass through underwater. There are DVL, EM-Log, and RPM in the speedometer, and the sensors are applied according to the system environment. This paper describes velocity aided navigation using RPM of inertial navigation system operating in high speed and deep water environment. In addition, we proposes an algorithm to compensate the limit of RPM with straight direction and the current velocity error. There are results of monte-calo simulation to prove performance of the proposed algorithm.