• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.300-303
• /
• 2004

In this paper, floor impact noise reduction in a cruise ship cabin by using floating floor is studied. A mock-up is built by using 61 steel plate, and two identical cabins are made where 25t panel is used to construct wall and ceiling inside the steel structure. Various floating floor systems are tested for which normalized impact noise is measured according to ISO 140-7 It is shown that effect of VL(Visco-elastic Layer) is negligible when it is used between deck and mineral wool, since most vibration absorption occurs in the wool. In addition, direction of the mineral wool fiber affects impact noise significantly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.612-618
• /
• 2000

The underwater explosion which has the high energy brings about the shock wave and the pulsating gas bubble. In general, structural vibration from the shock wave is more serious than the pulsating gas bubble. This shock wave may damage the important fragile structures and equipment in ship. This paper demonstrates that the shock wave propagating the structure can be reduced by ER inserts. The wave transmission of ER inserted beam is theoretically derived using Mead & Markus model, and the theoretical results are composed with the finite element analysis results. To experimentally verify the ER insert, ER insert in an aluminum plate is made and two piezoceramic disks are used as transmitter and receiver. Details of the experiment are addressed.

• Journal of Ocean Engineering and Technology
• /
• 제11권4호
• /
• pp.249-261
• /
• 1997

A basic study on the lifting lug design has performed through the rational and systematic process. In order to evaluate the proper design-load distribution around lug eye investigation of contact force between lifting lug and shackle pin is performed using non-linear parametric analysis idealized by gap element models. Gap element modeling and nonlinear analysis procedures are illustrated and discussed based on MSC/NASTRAN. Some analysis and design guides are suggested through the consideration of several important effects such as stress distribution pattern, circumferential contact force distribution along the lug eye face, loading share rate between lug main plate and doubler, effect of loading direction, relation between applied force and deflection and size effect of shackle pin radius. Additionally optimum design studies are performed and general trends according to the variation of design parameters are suggested.

• Proceedings of the KIPE Conference
• /
• 전력전자학회 2006년도 전력전자학술대회 논문집
• /
• pp.158-162
• /
• 2006

A lot of pieces of iron plate are used to build a ship. The states of cutting surface of iron are however bended or ununiformly cuttled by cutting machine. These may cause bad Quality of painting, and shorter lifetime of iron by rust. In this paper, a new approach of grinding force control method which teaching of robot is not required is proposed to avoid long preparation time of robot and to improve the productivity. The way used in this paper is just like a blind man works through the road with stick only.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• 제23권5호
• /
• pp.394-400
• /
• 2013

Underwater radiated noise is one of the important performances related to stealth of the naval vessel. However, the evaluation can't be performed frequently due to the cost. Therefore, the estimation method of the underwater radiated noise with average hull vibration is suggested in this paper assuming that the hull of the ship is infinite plate which consists of various unit plates. Through the experiment, the estimated noise is verified from the comparison to the measured data. In addition the difference of underwater radiated noise according to the operating equipments is estimated with measured vibration velocity.

• Journal of Ship and Ocean Technology
• /
• 제2권1호
• /
• pp.42-57
• /
• 1998

Genetic Algorithm (GA) is applied to obtain optimal Inspection plan for fatigue deteriorating structures. The optimization problem is defined so as to minimize inspection cost in the 1ifs-time of the structure under the constraint that the increment of failure probability in each inspection interval is maintained below a target value. Optimization parameters are the inspection timing and the inspection quality. The inspection timing is selected from the discrete intervals such as one year, two years, three years, etc. The inspection quality is selected from the followings; no inspection, normal inspection, sampling inspection or precise inspection. The applicability of the proposed GA approach is demonstrated through the numerical calculations assuming a structure consisting of four member sets. Influences of the level of target failure probability, initial defect condition and stress increase due to plate thickness reduction caused by corrosion on inspection planning are discussed.

• Journal of the Society of Naval Architects of Korea
• /
• 제41권5호
• /
• pp.41-47
• /
• 2004

In this paper, floor impact noise reduction in cruise ship cabin is studied. A mock-up is built by using 6t steel plate, and two identical cabins are made where 25t panel is used to construct wall and ceiling inside the steel structure. Various floating floor systems are tested for which normalized impact noise is measured according to ISO 140-7. In addition, floor SBN (Structure-borne Noise) and floor damping are measured to study the effect of floating floor structure. It is shown that VL(Visco-elastic Layer) is more effective when hard plates are added above the VL.

• Proceedings of the KWS Conference
• /
• 대한용접접합학회 2005년도 추계학술발표대회 개요집
• /
• pp.23-25
• /
• 2005

This paper presents a numerical analysis method for predicting welding-induced deformation and buckling in ship block with thin plates. The numerical method is particularized on evaluating buckling distortion induced by welding. There are two steps in the numerical analysis model. One is to solve the eigenvalue problem of welded structure by elastic buckling analysis, and the other is to solve the welding-induced buckling distortion of welded structure by post-mechanical analysis. Equivalent force method was used for considering the shrinkage force by welding in the analysis model.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• 제19권12호
• /
• pp.1329-1337
• /
• 2009

Because the tonal sound of the underwater noise in a naval vessel can be identified from the sub-marine of the enemy, it should be reduced sufficiently. This kind of the noise usually comes from the structure-borne noise of the onboard machine and transfers to the sea through the hull of the ship. The vibration at the high frequency can be reduced sufficiently with damping material. In this paper, the damping coefficient of the steel plate with damping sheet is evaluated by experiment. Using these evaluated properties, the numerical analysis is performed in order to evaluate how much vibration of the generator can be reduced applying damping sheet on the encloser and base of it.

• Special Issue of the Society of Naval Architects of Korea
• /
• 대한조선학회 2007년도 특별논문집
• /
• pp.22-25
• /
• 2007

Angular distortion in welding process is decided by the various variables. We can make the prediction of welding distortion in similar reality by the analysis of data through many specimen tests. However it is difficult that prediction of welding distortion applies to the ship building. We can establish that angular distortion varies directly as the specimen size. And, it makes clear distortion's difference between constraint and unconstraint, according to the change of a plate thickness.