S.Y. Hong

Kriso · offhsore palnt research division

As the size of container ships increases, the springing and whipping phenomenon has been among important design considerations due to its significant effect on wave loads and fatigue analysis. Thus the need for reliable model test data is increasing for validation of state-of-the-art analysis tools for the springing and whipping. In the present stu...

A time domain analysis of the hydroelastic deformation of a pontoon-type very large floating structure (VLFS) is investigated considering the horizontal motion effect. In our previous study on time domain analysis, the only vertical motion of VLFS was considered in the analysis of hydroelastic responses, which is appropriate for operational conditi...

An influence of sea-bottom topography on the hydroelastic response of a Very Large Floating Structure (VLFS) is considered. When the floating structure is constructed near the shore, the sea-bottom topographical effect should be considered. In this study, the effect of sea-bottom topography is investigated for four different bottom cases. To calcul...

This paper aims to investigate the basic interaction characteristics of side-by-side moored vessels both numerically and experimentally. A higher-order boundary element method (HOBEM) combined with generalized mode approach is applied to analysis of motion and drift force of side-by-side moored multiple vessels (LNG FPSO, LNGC and shuttle tankers)....

Experimental and numerical studies were performed on the hand-over operation of a riser between an installation vessel and an FPSO. A series of model tests were conducted in the Ocean Engineering Basin of KRISO. In the model test, a riser truncation model was introduced considering the limited depth of the basin and pit diameter. In addition, a non...

In this study, the Hopf bifurcation problem with regard to the nonlinear dynamics of a towed vessel was numerically investigated. A time-domain simulation method based on three degrees-of-freedom maneuvering equations of motion was applied to study the nonlinear dynamic responses of a towed vessel in calm water, wind and waves. In the towing operat...

In this study, a series of model tests were performed to study the relative wave elevation responses around a tension leg platform (TLP) in extreme waves. It is well known that a high relative wave elevation causes a horizontal wave impact or a wave-in-deck impact which can result in a serious damage on both fixed and floating offshore structures....

Recently, as the offshore structures are operated in the deep-sea oil fields, interest in the analysis of relative wave elevation around platforms is increased. In this study, it is examined how the analysis results differ depending on the characteristics of the wave probe when interpreting the relative wave elevation in the model test. First, by c...

An experimental investigation of the characteristics of the slamming impact loads on the bow of a ship-type Floating Production Storage and Offloading (FPSO) under breaking and irregular wave conditions was conducted. The breaking waves were generated by the focusing wave method and three different heading angles were applied. To examine the repeat...

This paper presents ISOPE’s 2020 comparative study on the interaction between focused waves and a fixed cylinder. The paper discusses the qualitative and quantitative comparisons between 20 different numerical solvers from various universities across the world for a fixed cylinder. The moving cylinder cases are reported in a companion paper as part...

In this paper, the comparative study carried out for focused wave interaction with a moving cylinder in ISOPE-2020 is reported. The fixed cylinder cases are reported in the companion paper as Part A (Sriram, Agarwal, Yan et al., 2021). The paper discusses qualitative and quantitative comparison between four different numerical solvers that particip...

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...

This paper summarizes a joint effort, TESK JDP, initiated by TechnipFMC, ExxonMobil Upstream Research Company (EMURC), Samsung Heavy Industries (SHI) and Korea Research Institute of Ships & Ocean Engineering (KRISO) in order to develop reliable modeling practices for the application of Computational Fluid Dynamics (CFD) to the design of the offshor...

To study the motions and flooding process of a damaged cruiser, a series of experiments and numerical calculations have been performed in calm water and in waves. Two damaged scenarios are selected to investigate effect on the motions and flooding process; midship section and fore section. The results of the experiment, relating to the quasi-static...

Bow-flare slamming is issue that must be considered in ship design because it affects the local strength and fatigue life of a ship. In this paper, the experimental study of the spatial distribution of slamming load was conducted, which acts on the bow flares of ultra-large containerships. For a model test, 10,000 TEU container ship model with 1/60...

This paper presents a numerical sensitivity analysis for the simulation of the motion performance of an offshore structure in waves using computational fluid dynamics (CFD). Starting with 2D wave simulations with varying numerical parameters such as grid spacing and CFL value, proper numerical conditions were found for accurate wave propagation tha...

In this study, an experimental and numerical analysis have been carried out to investigate the coupled behavior of a Tension Leg Platform (TLP) combined with a tender semi-submersible platform with focus on the multi-modal behaviors. Free decay tests were conducted for the TLP and semi-submersible, which showed that the TLP and semi-submersible sys...

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 an...

A fully coupled analysis is carried out to evaluate the offshore mating operation for a large heavy topside module on a deck of floating liquefied natural gas (FLNG). Fully coupled hydrodynamic interactions are considered between a crane vessel lifting the heavy topside module and the FLNG. Multiple crane wires and slings are modeled with linear sp...

In this study, a series of model tests were carried out to evaluate the performance of an active heave compensator (AHC) in deepwater installation operations. In the tests, a crane vessel and three different subsea structures were examined during deepwater crane lifting operations with an AHC. To validate the experimental results, time-domain numer...

Wave-in-deck impacts in extreme waves can cause a serious damage on both fixed and floating offshore structures. In particular, tension leg platform (TLP) can be exposed to frequent wave-in-deck impact events due to good vertical motion performances as well as wave amplifications inside columns. In this study, the wave-in-deck impact event as well...

A comparative study of a water-entry problem was conducted as a focused session of ISOPE-2016, Rhodes by the International Hydrodynamic Committee (IHC) of ISOPE. Thirteen institutions participated, and twenty different numerical results were investigated and compared with one another and with model test data. Some promising results were obtained ev...

There are many experimental studies of the measurement of the water impact load. Pressure sensors are widely used to measure the water impact load, but there are few papers handling the characteristics of the pressure sensor thoroughly. The present study investigates the characteristics of the pressure sensor for the measurement of the water impact...

The floating crane vessel in waves gives rise to the motion of the lifted object which is connected to the hoisting wire. The dynamic tension induced by the lifted object also affects the motion responses of the floating crane vessel in return. In this study, coupled motion responses of a floating crane vessel and a lifted subsea manifold during de...

This paper compares five numerical methods for calculating drift forces in time domain analysis of moored bodies. The first method is the most basic one. It uses all terms of QTF (quadratic transfer function) matrix based on double summation. It is the most correct due to no approximation but needs large memory and cpu time. The second method uses...

This paper presents an experimental study of the deepwater lifting and lowering operations of a subsea manifold. A series of model tests with an installation vessel, a crane system, and a manifold were performed at the Ocean Engineering Basin of the Korea Research Institute of Ships and Ocean Engineering (KRISO). The lifting and lowering operations...

A time-domain simulation method based on potential flow model has been developed to investigate the berthing problem between two floating bodies in wave. The boundary value problem is formulated with respect to an earth-fixed coordinate system because the relative positions of the two vessels continuously change during the berthing operation. The c...

An experimental study on a subsea installation using an offshore crane was conducted. Concrete blocks, suction piles, and manifolds were considered in this study. Free decay tests were conducted to investigate the fluid characteristics of the subsea structures. The added masses of the structures were estimated. The motion response amplitudes of the...

Berthing is a common marine operation frequently occuring in harbors and at open sea. It involves a moving vessel closely approaching a moored offshore structure or a pier from a far distance. During the berthing operation, the distance between the stationary structure and berthing vessel decreses continuously, resulting in increasing hydrodynamic...

In this study, crane installation operations of subsea equipment in deep water are experimentally investigated. A series of model tests for the deepwater lifting operation were performed at Ocean Engineering Basin of KRISO. For the model test, an installation vessel with dynamic positioning system, and a crane system were introduced. Among various...

An experimental study of a 2 × 2 array of interlinked spars was performed in order to identify the motion and structural responses and to determine the feasibility of this system. The motion responses of the floaters were measured with noncontact cameras, while the tension in the connectors and mooring lines was measured with single-axis load cells...

In this paper, the dynamics of multiply inter-linked SPAR structures using connector beams are studied using a commercial numerical code ‘OrcaFlex’ and the results are compared with experimental results. Multiple SPAR structures are inter-linked by connector beams, and the mooring lines are used only for the outermost SPARs. The basic module is fou...

This study consists of an experimental investigation of the reduction of the second-order roll motion of a semi-submersible platform in head sea conditions by adding hull damping. The second-order heave drift force and roll drift moment are known to be the main triggers that induce the list angle (Hong et al., 2010). Hong et al. (2013) used numeric...

This paper compares simplified and finite element method (FEM) models for tower and blade in dynamic coupled analysis of floating wind turbine. A SPAR type wind turbine with catenary mooring lines is considered in numerical analysis. Floating body equation is derived using boundary element method (BEM) and convolution. Equations for mooring line, t...

In this study, the berthing problem in waves is numerically investigated by a time-domain simulation method based on a potential flow model. The boundary value problem for a berthing operation is formulated with respect to an earth-fixed coordinate system. The Laplace equation of a moving boundary problem is solved using the finite element method b...

This paper presents the results of a numerical study on the towing characteristics of a barge under various wind conditions. First, stability criteria, including the wind force, were derived based on the linear motion equations of a towed vessel. The effect of the wind force on the towing stability was investigated using stability criteria. Next, t...

A series of integrated simulations of a deep-water crane vessel system composed of four sub components, floating vessel, lifted equipment, hoisting cable and dynamic positioning (hereinafter DP) system were carried out by using nonlinear time-domain analysis method. Analysis of coupled dynamics includes the crane vessel and equipment connected via...

In this study, the motion characteristics of Ocean Thermal Energy Conversion (OTEC) platforms are investigated by experimental and numerical methods. A series of model tests for octagon-shaped Sevan OTEC platforms were carried out in Ocean Engineering Basin of KRISO(68.8m × 37m × 4.5m, Experimental area: 56m × 28m × 3.2m). Two experimental models s...

This paper presents an experimental study on deepwater crane installation operation in waves. Model tests with crane vessel, manifold and crane system were carried out at Ocean Engineering Basin of KRISO. To overcome the limitation of water depth in basin, new experimental method using truncated hoisting system is introduced. Lifting and lowering o...

A numerical method to investigate the non-linear motion characteristics of a TLP is established. A time domain simulation that includes the memory effect using the convolution integral is used to consider the transient effect of TLP motion. The hydrodynamic coefficients and wave force are calculated using a potential flow model based on the HOBEM(h...

Springing and whipping are becoming increasingly important considerations in ship design as container ships increase in size. In this study, the springing and whipping characteristics of a large container ship were investigated through a series of systematic model tests in waves. A multi-segmented hull model with a backbone was adopted for measurem...

In the present study, the water impact loads on two-dimensional symmetric and asymmetric wedges are mainly studied. The impact pressure and forces are measured during the vertical drop of the symmetric and asymmetric wedges. The drop velocity of wedge is evaluated from the measured acceleration and displacement. The measured pressures are compared...

Bow-flare slamming has been paid attention in ship classification societies because it causes local damage or severe whipping vibrations which affects the ultimate strength and fatigue life of ship. WILS JIPIII (Wave Induced Loads on Ships Joint Industry Project-III) has been launched and conducted by KRISO, Korea, of which aims are to measure the...

The radiation-diffraction potential of a ship advancing in waves is studied using the three-dimensional frequency-domain forward-speed free-surface Green function (Brard 1948) and the forward-speed Green integral equation (Hong 2000). Numerical solutions are obtained by making use of a second-order inner collocation boundary element method which ma...

We comparatively investigated wave-induced motions of two floating pendulum wave energy converters (WECs): one designed to reduce motion response via a damping plate and the other designed to reduce motion response via a large water-plane area. The motion responses were compared through model tests under operational and survival wave conditions and...

This paper presents the results of an experimental and numerical study on the towing characteristics of a barge. A series of model tests were carried out at the Ocean Engineering Basin of KRISO. A model with a 1:50 scale ratio was constructed out of wood. First, force coefficient tests were performed in order to obtain the surge, sway, and yaw forc...

In this paper, we carried out a numerical investigation of the hydrodynamic performance of a floating pendulum wave energy converter (WEC). This movable-body-type device consists of three main parts: floater, pendulum and damping plate. The performance of the WEC device was evaluated under regular and irregular wave conditions using frequency-domai...

This paper presents the results of an experimental study of wave run-ups on a semi-submersible offshore structure. A series of model tests with a 1:80 scale ratio were carried out in the two-dimensional wave basin of MOERI/KIOST. The experimental model had two columns and one pontoon. The model was fixed and wave elevations were measured at five po...

We comparatively investigated wave-induced motions of two floating pendulum wave energy converters (WECs): one designed to reduce motion response via a damping plate and the other designed to reduce motion response via a large water-plane area. The motion responses were compared through model tests under operational and survival wave conditions and...

In 2008~2013, KRISO (Korea Research Institute of Ships & Ocean Engineering) developed technologies for FSRU (Floating Storage Regasification Unit) engineering. Time domain dynamic coupled solver for floating body and mooring lines is one of the key results of the FSRU project. By applying the solver, this paper investigates dynamic behavior of FSRU...

Recently, the float-over installation is used to install the topside deck module of offshore structure. The main advantage is the modular installation of the large topside without lift vessel. It gives short installation time and avoids the rental difficulty of the lift vessel. And the cost reduction is also expected because all of fabrication and...

This paper presents a numerical study on motion characteristics of a Tension Leg Platform (TLP) in waves. Time-domain simulation using convolution integral is applied to investigate the wave-induced motion response of the TLP. Hydrodynamic coefficients and wave forces are calculated using higher-order boundary element method (HOBEM) based on potent...

This paper presents an experimental and numerical study on towing characteristics of a transportation barge during multi-tug operation. Model tests were carried out at Ocean Engineering Basin of KRISO. The motion of a towed transportation barge during multi-tug operation was measured. Numerical simulations based on the maneuvering model were conduc...

The hydrodynamic interaction between two bodies floating side-by-side in close proximity was studied using a nine-node discontinuous higher order boundary element method based on the conventional two-body formulation (9dHOBEM) and a constant boundary element method based on the boundary matching formulation (BM-CBEM). It has been shown that unreali...

This paper compares the dynamic coupled behavior of floating structure and mooring system in time domain using two numerical methods for the mooring lines such as the linear spring method and the nonlinear FEM (Finite Element Method). In the linear spring method, hydrodynamic coefficients and forces on the floating body are calculated using BEM (Bo...

In deepwater installation and lift, amplified vertical motions of equipment can be caused by axial resonance of wire. This can occur even in operational sea state due to the elastic behavior of the wire. In order to reduce the vertical oscillatory motion of the lifted equipment, heave compensation systems have been frequently used in the subsea ins...

This paper presents the results of a numerical study on the towing stability of barges. Towing simulations were carried out by using two different numerical models (MMG model and cross-flow model). Stability criteria are also suggested based on the analysis of the linearized governing equations for towed vessel motion. In order to validate the pres...

Various artificial damping schemes for progressive water waves were evaluated in a three-dimensional numerical wave tank (3D NWT). Five types of damping schemes were applied to the end of a computational domain and their damping capabilities were compared to find an optimum artificial damping scheme. The 3D NWT was based on a nine-node, bi-quadrati...

Turret moored floating body, such as FPSO, FSRU and FSU weathervanes on a turret according to wave, current and wind. Turret moored body can oscillate from side to side or move to one particular direction, and eventually shows large yaw motion. The yaw of turret moored vessel is one of factor to affect the motion performance, mooring load and offlo...

Wave-induced motion characteristics of multiple Spar-type floaters with elastic connectors and catenary mooring lines have been investigated in time domain. Hydrodynamic coefficients were achieved by using Green function with High-Order Boundary Element Method(HOBEM). Wave diffraction induced by other floaters was confirmed to be negligible as floa...

This paper presents an experimental and numerical study on towing characteristics of a transportation barge in waves. A series of model tests were carried out at the Ocean Engineering Basin of MOERI/KIOST for measurements of hull forces and motion of a towed transportation barge model in calm water and in waves. Two numerical simulations based on M...

The floating offshore wind turbines(FOWTs) are considered as a promising candidate due to high-quality of wind energy and environmental friendliness. There are typical three types of conceptual design of FOWTs such as Spar, Semi-submersible, and TLP. Recently, "Hywind-OC3" spar and "WindFloat" semi-submersible type structures as 5MW class have been...

The goal of this study was to optimize the design of motion reduction structures for a floating pendulum-type wave energy converter (WEC) used to harness energy from the ocean. The purpose of these structures was to improve the performance of the WEC by reducing its motion under operating wave conditions and by helping the device absorb wave energy...

FSRU (Floating Storage Re-gasification Unit) project was carried out by MOERI/KIOST during 2008~2013 and they developed core engineering technologies for FSRU. As a key result of the project, time domain dynamic coupled solver for floating body and mooring lines was developed and it was applied to performance analysis of single body FSRU system wit...

Motion of a heavy transport vessel in waves is numerically investigated by using a method of nonlinear time-domain analysis for floating body motion. In this study, focus is made on the roll motion of the transport vessel which is significantly influenced by nonlinear wave loads acting on the transported offshore structure. The present numerical me...

The motions and drift forces of side-by-side moored FSRU and LNGC including the sloshing effect, were studied using experiments. The FSRU and LNGC contained LNG cargo tanks and the LNG sloshing could affect the motions and drift forces of the structures due to its coupling with floating body motion. The effect of coupling can vary with the LNG fill...

This paper presents a numerical study of the wave loads acting on offshore structures using a Cartesian-grid-based flow simulation method. Finite volume discretization with a volume-of-fluid (VOF) method is adopted to solve two-phase Navier-Stokes equations. Among the many variations of the VOF method, the CICSAM scheme is applied. The body boundar...

The characteristics of an impact load and pressure were experimentally investigated. Drop tests were carried out using a modified Wigley with CB = 0.56. The vertical force, pressures, and vertical accelerations were measured. A 6-component load cell was used to measure the forces, piezo-electric sensors were used to capture the impact pressure, and...

This paper investigates the statistical properties of waves in the sea area of Uljin, which is located in the East Sea area of Korea. The wave data were measured using AWAC (Acoustic Wave and Current Meter), which was installed at a 16-m water depth from November 2010 to March 2011. The wave data acquisition rate, Hmax, monthly mean Hs, Tz, Tp, and...

This paper presents numerical simulations of a diffracted wave around a bottom-mounted circular cylinder using the volume-of-fluid (VOF) method. Unsteady incompressible Navier-Stokes equations are solved based on the finite volume method (FVM) with a collocated variable arrangement. The SIMPLE-type correction algorithm with the momentum interpolati...

A coupled analysis of a floating crane barge with a crane wire and hanging structure is carried out in thetime domain. The motion analysis of the crane barge is based on the floating multi-body dynamics, and thecrane wire is modeled as a simple spring tension. The hanging structure is assumed to be a rigid body with 3 degree-of-freedom translationa...

In this study, a numerical analysis of offshore installation using a floating crane with heave compensator is carried out in time domain. The motion analysis of crane vessels is based on floating body dynamics using convolution integral and the crane wire is treated as simple spring. The lifted structure is assumed as a rigid body with 3 degree-of-...

In the present study, a numerical and experimental study is conducted for a floating wind tower substructure of 5MW capacity. The design targets are cost effective, smaller draft than SPAR, simple to construct and install. The basic idea for shape design comes from the truss-spar which utilizes a large heaving plate for enhancing global performance...

In this paper, we carried out a numerical investigation of the hydrodynamic performance of a floating pendulum wave energy converter (WEC). This movable-body-type device consists of three main parts: floater, pendulum and damping plate. The performance of the WEC device was evaluated under regular and irregular wave conditions using frequency-domai...

A box-type floating structure is considered for a candidate of floating wind turbine structures. The platform is consisted of a box structure and large damping plates for enhancing global performance characteristics. Numerical analysis is conducted by using higher-order boundary element method. The numerical results were validated through a series...

Global performance of an array of floating wind turbine structures is investigated through numerical analysis by using 9-node higher-order boundary element method. Multi-body hydrodynamic interaction between floating wind turbine structures is considered based on generalized mode approach. Connecting structures between floating wind turbines is dev...

KORDI (Korea Ocean Research and Development Institute) carried out FSRU (Floating Storage Re-gasification Unit) project during 2008∼2011 and developed core technologies of FSRU engineering. As parts of the project, time domain coupled solver for body & mooring and fatigue analyzer for mooring lines were developed and they were applied to fatigue as...

A deepwater lifting operation using crane vessel is investigated by a time-domain analysis program for floating crane vessel systems. In the analysis, a coupled analysis of floating vessel and lifted object dynamics connected via crane wire are simulated with and without heave compensator. For deepwater installation cases, amplified vertical motion...

The second-order motion characteristics of a semi-submersible are investigated in regular waves. A higher-order boundary element method in a frequency domain and a finite element method in a time-domain were ap-plied to the numerical analysis of the nonlinear hydrodynamic force and motion characteristics of semi-submersibles in view point of potent...