• Journal of Navigation and Port Research
• /
• v.38 no.1
• /
• pp.11-18
• /
• 2014

To confirm whether the square tank at Changwon National University (CWNU) can be used for estimation of maneuverability, planar motion mechanism (PMM) test and circular motion (CM) test were performed for various conditions. PMM test can be implemented using an XY carriage and a yaw table in the square tank. However, sometimes test section is insufficient for PMM test owing to low length-breadth ratio of the tank. In addition, the speed of a towing carriage is also quite limited. Therefore, it would be useful if PMM test could be effectively performed diagonally, by establishing coupled control logic to drive three servomotors. In addition, Froude number dependency on the estimated hydrodynamic coefficients was checked. Furthermore, CM tests, which cannot be completed in a conventional linear towing tank, were performed, and its results were compared with the results of PMM test. The results of the PMM tests in the diagonal direction were consistent with the results of the test performed in the direction parallel to the sidewall. However, the results of the CM test were greater than those of the PMM test. This tendency was also observed in the results published at Ulsan University.

• Journal of Ocean Engineering and Technology
• /
• v.16 no.6
• /
• pp.25-31
• /
• 2002

A system identification method is introduced to increase the prediction accuracy of a ship's maneuverability in PMM test, analysis. To improve the accuracy of linear hydrodynamic coefficients, the analysis techniques of pure sway and yaw tests are developed, and confirmed. In the analysis of sway tests, accuracy to linear hydrodynamic coefficients depends on the frequency of sway motion. To obtain nonlinear hydrodynamic coefficients for large drift angles, a combined yaw test is introduced. Using this system identification method, runs of PMM test can be reduced while retaining sufficient accuracy, compared to the Fourier integration method. Through the comparisons with sea trial results and the Fourier integration method, the accuracy and efficiency of the newly proposed system identification method, based on least square method, has been validated.

• Journal of the Society of Naval Architects of Korea
• /
• v.48 no.5
• /
• pp.465-472
• /
• 2011

Recently, ultra large scale of ship is being ordered continuously and because of that, the accurate prediction of ship maneuverability in design stage becomes important matter. The model test like PMM test or CFD analysis are representative methods for predicting the maneuverability of ship. In this study, the captive model tests were carried out for predicting maneuverability of MOERI container ship(KCS) which is opened to the public using X-Y Carriage of Ocean Engineering Wide Tank of University of Ulsan. Considering the dimensions of tank, 2m class model ship was used for captive model test. CMT(Circular Motion Test) was performed for obtaining purer hydrodynamic coefficients related to yawing velocity. For getting hydrodynamic coefficients which cannot be obtained using CMT, PMM test(Planar Motion Mechanism test) were also performed. The maneuverability prediction results by simulation are compared with those of other research institutes.

• Journal of the Society of Naval Architects of Korea
• /
• v.46 no.3
• /
• pp.259-267
• /
• 2009

Recently, ship maneuverability has been very important issue due to accidents of frequent occurrence at sea. IMO standards for ship maneuverability were applied from January 1, 2004. In this study, maneuverability model tests were considered through a 2m-class KVLCC1 in the Ocean Engineering Wide Tank at University of Ulsan(UOU). Circular Motion Test(CMT) was performed to obtain the maneuvering coefficients by using X-Y Carriage. The trajectories simulated using the coefficients are compared with those of PMM test and free running test.

• Journal of Navigation and Port Research
• /
• v.34 no.7
• /
• pp.525-532
• /
• 2010

Mobile Harbor (MH) is a new transportation platform that can load and unload containers onto and from very large container ships at sea. It could navigate near harbors where several vessels run, or it could navigate through very narrow channels. In the conceptual design phase when the candidate design changes frequently according to the various performance requirements, it is very expensive and time-consuming to carry out model tests using a large model in a large towing tank and a free-running model test in a large maneuvering basin. In this paper, a new Planar Motion Mechanism(PMM) test in a Circulating Water Channel (CWC) was conducted in order to determine the hydrodynamic coefficients of the MH. To do this, PMM devices including three-component load cells and inertia tare device were designed and manufactured, and various tests of the MH such as static drift test, pure sway test, pure yaw test, and drift-and-yaw combined test were carried out. Using those coefficients, course-keeping stability was analyzed. In addition, the PMM tests results carried out for the same KCS (KRISO container ship) were compared with our results in order to confirm the test validity.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.71-72
• /
• 2022

In this paper, the performance evaluation of the vibration damping ratio according to the polymer mixing ratio of the polymer modified mortar used as the floor finishing material of the apartment building structure was evaluated. To compare the vibration damping rate, ordinary potland cement (OPC) mortar and polymer modified mortar (PMM) were prepared. In addition, the mixed polymer was mixed with Styrene Butadiene Rubber (SBR) liquid polymer with a solid content of about 49%. Accordingly, the W/C of the test specimen was adjusted and compounded, and the experiment was conducted by mixing 5 types of the test specimen: OPC-60, PMM-5%, PMM-10%, PMM-15%, and PMM-20%. In addition, in order to adjust the W/C of the specimen, the fluidity of each specimen was set as 210 (±5) mm. The specimens measured density and flow in fresh mortar and after curing for 28 days, flexural strength, compressive strength and ultrasonic pulse were measured. The attenuation rate was shown. The experimental results showed that the density increased according to the mixing of the polymer, the flexural strength increased as the mixing rate of the polymer increased, and the compressive strength was decreased. In addition, it was shown that the vibration damping rate increases with the increase in the amount of polymer incorporated.

• Journal of the Society of Naval Architects of Korea
• /
• v.45 no.3
• /
• pp.280-287
• /
• 2008

In this paper, a mathematical model for a ship manoeuvring with low forward speed in shallow water was suggested. Based on the cross flow model with low forward speed in deep sea, hull, propeller and rudder models were modified to consider the shallow water effects. Static drift and PMM tests were performed to obtain the cross flow drag coefficients and hydrodynamic coefficients. To validate suggested mathematical model, numerical simulation results were compared with those of sea-trials. Through comparisons, it was concluded that suggested mathematical model could give proper estimation on turning test results.

• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.1
• /
• pp.46-53
• /
• 1998

In this paper, we studied to improve Inoue's[1] and Kijima's[2] model used to predict ship's manoeuvrability at initial design state. To perform this work, we carried out PMM(Planar motion Mechanism) test and rudder open water test for 12 models of low-speed blunt-ship which have horn type rudders and bulbs in afterbody. As we adopted MMG(Mathematical Modelling Group) model, we could analyze hydrodynamic and MMG experimental coefficients. The regression analyses by principle parameters were carried out for hydrodynamic and MMG experimental coefficients. The regression analyses by principle parameters were carried out for hydrodynamic and MMG experimental coefficients and the equations by regression analysis wee used to search sensitivities and to estimate ship's manoeuvrability. We had simulated ship's manoeuvrability to check revised MMG.

• Journal of the Korean Institute of Navigation
• /
• v.21 no.2
• /
• pp.11-17
• /
• 1997

In this paper, we studied to improve Inoue's[1] and Kijima's[2] model used to predict ship's manoeuvrability in initial design stage. To perform this work, we had PMM(Planar Motion Mechanism) test and rudder open water test for 12 Models of low-speed blunt-ship which have horn type rudder and bulb in afterbody. Using MMG(Mathematical Modelling Group) model, we analyzed hydrodynamic and MMG experimetnal coefficidnts used to search sensitivities and to estimate ship's manoeuvrability, adn the results are performed by the regression analysis of principle parameters. We varified them to analyze ship's manoeubbrability , had simulate manoeubrability to check revised MMG model and compared them wiht Inoue's method. the result of PMM test and sea trial. Then it is found that the revised method can predict the maneuverability more accurately even for an unstable ship.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.3
• /
• pp.31-37
• /
• 1990

To obtain the values of linear stability derivatives, both analytical and experimental methods are now proposed and in use. The experimental method is well known as the planar motion mechanism(PMM) test. Its concept is to drive the model with a prescrived frequency and amplitude of the motion and pick up the hydrodynamic forces. But this kind of method is inconvenient in case we want to know the stability derivatives in wider range of the frequencies. So a different method is attempted that with one test run, we can get the derivatives in wider range of the frequencies. This technique forces the impulsive motion on the model, using the power of the oil pressure pump. This kind of method was originated by Scragg, C.A., Cummins, W.E, or Frank, T., This resarch is a further development of such preceding works. Todd's series 60(Cb=0.7) 2.00M model is chosen for the test and the results are compared with Van Leeuwen's famous PMM test results.