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In this study, experimental and numerical methods were applied to estimate surge and sway wave drift forces and yaw drift moment acting on KVLCC2, advancing in oblique wave. An experiment was carried out in the ocean engineering basin of the Korea Research Institute of Ships and Ocean Engineering (KRISO). A series of regular wave tests under various heading conditions were conducted to investigate ship motion responses and wave drift forces. A Rankine panel method based on potential flow was adopted in the numerical analysis, and the direct pressure integration method that integrates second-order pressure on the hull surface was applied to compute wave drift force. Through this study, validation data of wave drift force acting on KVLCC2 was established, and the computation capability of the potential-based numerical method was systematically analyzed.

In this study, an experimental and numerical study was conducted for investigating the mating operations of a topside module onto a FLNG by using a floating crane in waves. A series of model tests were performed in Ocean Engineering Basin at KRISO with a model set-up of 1:45 scale ratio. The floating crane vessel was equipped with a crane system and dynamic positioning system. The topside module was simplified as a rectangular box of about 2000 Tonf. Four leg mating units(LMUs) were introduced to model the interface units between the FLNG and the topside module. While the interaction forces between the crane vessel and the topside module are transferred via the crane wires, the topside module interacts with the FLNG through the LMUs. Experimental conditions include four different mating stages, i.e. 0%, 20%, 50% and 93% load transfers, under regular and irregular wave conditions. To validate the experimental data, a time-domain numerical simulation method is applied to solve the coupled dynamics of three bodies. The discussions were made on three main points. First, the motion characteristics of the lifted object as well as the crane vessel were investigated by comparing the simulation results. Second, the dynamic tensions of the crane wires were evaluated under the various wave and mating conditions. Final discussion was made on the LMU impact forces.

In this study, a prediction method of the form factor for a full-scale ship is suggested to minimize the power prediction error from a small model ship. Numerical simulations were carried out at various Reynolds numbers from a small model to a full-scale ship. The variation of the form factors was investigated from the results of the numerical simulation according to the Reynolds numbers. In addition, the results from the numerical simulations and experimental data of the geosim models were utilized to drive the correlation line and predict the form factor of a full-scale ship. The correlation line was applied to predict the effective power and the delivered power of a full-scale ship. As a result, the developed prediction method confirmed the possibility of predicting the power reliably from experiments using a small model.

This study considers the wave impact loads on the semi-submersible structure. To evaluate wave impact loads on the semi-submersible structure, a series of experiments are conducted in a 2D wave flume. In the experimental test, the semi-submersible half model is used, and 11 uniaxial force sensors are installed in deck side, column side, and deck bottom. Wave probes are, also, attached in the test model to measure the relative wave elevation. To generate horizontal and bottom wave impact on the test model, focusing wave is applied. The test model is fixed without any motion during each test, while the trim angle of the test model is changed to examine the effect of trim angle on wave impact load. Through this, the characteristics of the wave impact force at each position were investigated.

Structure Using the Modified Marker-density Method Yoon-Jin Ha . Young-Gill Lee .Kwang-Leol Jeong . In-Jun Yang Korea Research Institute of Ships and Ocean Engineering, KRISO, Daejeon, Korea Dept. of Naval Architecture and Ocean Engineering, Inha University, Incheon, Korea Research Center, NEXTfoam Co., Ltd., Seoul, Korea Dept. of Naval Architecture and Ocean Engineering, Graduate School, Inha University, Incheon, Korea

In this study, a series of model tests was conducted to investigate the characteristics of wave impact loads and the associated air bubble effects on a vertical circular cylinder with various pressure and force sensors installed in a 2D wave flume. Spilling and plunging waves, generated by the focusing wave method, induced wave impact loads on the cylinder, and these loads were measured by the sensors, which had different natural frequencies and sensing areas. Each test condition was repeated 20 times to verify the repeatability of the impact loads and their effects. The air bubble effects were investigated by analyzing the time histories of the impact forces and pressures, and the effects were related to the natural frequency and sensing area of the sensors. The air bubble effects were observed to increase as the breaking wave developed more at the position of the cylinder. The generated waves and impact loads were also observed to change significantly when even a small noise occurred in the displacement of the wavemaker.