SungHo Park

Estimation of the Sound Radiation Efficiency of the Hull Considering the Type and Natural Frequency of Plates of It

The definition of the radiation efficiency is very important to estimated underwater radiated noise of a ship. Considering the structure of the ship, it can be found that the hull of a ship consists of a lot of plates supporting by longitudinal and transverse stiffener. Therefore, various modes of the hull vibration occur related to the combination of these plates including stiffeners. In this paper, the method to define the radiation efficiency is suggested considering the vibration mode of the hull based on Uchida`s experimental equation of the radiation efficiency. The suggested method is verified by the experiments with various kinds of naval vessels.

Analysis of the Vibration Fatigue for the Diesel Engine and Reduction Gear Connecting Shaft in a Ship

The diesel engine and reduction gear combination is one of the common propulsion system in a naval vessel. Since the diesel engine has torsional vibration caused by reciprocating motion of the mass and gas pressure force of the cylinder, high cycle torsional fatigue can be occurred. Therefore, ROK navy restricts the maximum stress of the propulsion shaft according to MIL G 17859D. In this paper, the root cause for the failure of the diesel engine and reduction gear connecting shaft occurred in typical naval vessel is investigated based on the measured bending and torsional moment according to MIL G 17859D procedure.

Investigation of the Effect for the Reverberation of a Shooting Blast Sound to the Structural Safety in the Military Shooting Range

Since the shooting blast sound in the military shooting range is extremely high, it can make a damage to the surrounding structure. Therefore, in the design state of the construction of the military shooting range, the building and structure should be arranged considering the induced sound pressure from the gun. In the typical military shooting range surrounding to test buildings described in this research, the measured impact sound level of the gun firing is higher than the design limit. Therefore, the root cause of this sound incresing is investigated in this research. The sound field characteristics in the military shooting range is experimently evaluated using signal gun. Using Palmgren Miner’s cumulative damage calculation method, the effect of the direct impact sound and reverberation sound for the building structure in the shooting range are investigated related to the endurance characteristics.

Estimation of Uncertainty in Vibration Measurement of Shipboard Equipment

This paper proposes estimation model of uncertainty in vibration measurement of shipboard equip- ment and analyzes the result of uncertainty estimation. Vibration of shipboard equipments affects un- derwater radiated noise that is important performance related to stealth of the naval vessel. Acceptance testing for shipboard equipment is required to guarantee the stealth performance of naval vessel. In measuring, detailed uncertainty estimation is essential to improve measuring reliability. Acceptance testing result of structure-borne noise and vibration is used to analyze uncertainty in vi- bration measurement of shipboard equipment.