• 한국해양공학회지
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• 제12권3호통권29호
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• pp.19-30
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• 1998

In this paper, the dynamic analysis of a dolphin system for mooring a floating structure such as barge mounted plant is studied. The characteristics of the soil-pile system are simplified by a set of equivalent spring elements at the mudline. To evaluate the equivalent spring constants, the finite difference method is used. Since the characteristics of the soil-pile system are nonlinear in case of soft foundation, the nonlinear dynamic analysis technique is needed. The Newmark $beta$ method incorporating the modified Newton-Raphson method(initial stiffness method) is used. A numerical analysis is performed on two mooring dolphin systems on soft foundation and rock foundation. In case of the rock foundation, the characteristics are found to be nearly linear, so the linear dynamic analysis may be sufficient to consider the foundation effect. But in case of soft foundation, the non-linearity of the foundation appears to be very signigicant, so the nonlinear dynamic analysis si needed.

• Ocean Systems Engineering
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• 제13권4호
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• pp.401-421
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• 2023

Reducing hawser line tensions and dynamic responses to a certain level is of paramount importance as the hawser lines provide important structural linkage between 2 body TLP-TAD system. The objective of this paper is to demonstrate how MR Damper can be utilized to achieve this. Hydrodynamic coefficients and wave forces for two bodies including second-order effects are obtained by 3D diffraction/radiation panel program by potential theory. Then, multi-hull-riser-mooring-hawser fully-coupled time-domain dynamic simulation program is applied to solve the complex two-body system's dynamics with the Magneto-Rheological (MR) Damper modeled on one end of hawser. Since the damping level of MR Damper can be changed by inputting different electric currents, various simulations are conducted for various electric currents. The results show the reductions in maximum hawser tensions with MR Damper even for passive control cases. The results also show that the hawser tensions and MR Damper strokes are affected not only by input electric currents but also by initial mooring design. Further optimization of hawser design with MR Damper can be done by active MR-Damper control with changing electric currents, which is the subject of the next study.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1155-1160
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• 2005

In order to evaluate the safety of navigation at sea and the safety of mooring ship on berthing, it is necessary that the wave and wind induced ship dynamic motion should be measured in real time domain for the validity of theoretical evaluation method such as sea-keeping performance and safety of mooring. In this paper, the basic design of sensors is discussed and some system configurations were shown. The developed system mainly consists of 4 kinds of sensors such as three dimensional accelerator, two dimensional tilt sensor, two displacement sensors and azimuth sensor. Using the this measuring system, it can be obtained the 6 degrees of freedom of ship dynamic motions at sea and on berthing such as rolling, pitching, yawing, sway, heave, surge under the external forces.

• 한국해양공학회지
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• 제30권4호
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• pp.253-259
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• 2016

This study demonstrates the result of mooring analysis for five spread-moored FPSOs having different length-to-breadth (L/B) ratios from 4.5–6.5. FPSOs are subjected to four metocean conditions, ones from the Gulf of Mexico (Hurricane/Loop current condition), West Africa, Nigeria, and Brazil Campos Basin, which are amongst the most typical offshore oil and gas fields. With change in design parameters of OBA (Outer bundle angle) and IBA (Inner bundle angle) combinations, a change in the line tension is demonstrated and the OBA-IBA combinations having the smallest line tension are presented for each L/B ratio and sea, respectively. This study is expected to influence the preliminary design layout of an FPSO spread-mooring system as a function of the L/B ratio and metocean conditions.

• Journal of Ship and Ocean Technology
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• 제9권1호
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• pp.11-26
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• 2005

In this study, the program to investigate the multiple body interaction effects between a floating platform and a shuttle tanker considering the coupled effect of hull (FPSO) with mooring lines and risers was developed. The coupled analysis program, which is called WINPOST-MULT using the hydrodynamic analysis results by WAMIT, was made. For the verification of WINPOST-MULT by means of numerical experiments, two multiple-body models of an FPSO-FPSO and an FPSO-shuttle tanker system are adopted. With the FPSO-FPSO model and a two-mass-spring system to idealize two identical bodies for the 100-year storm wave condition in GOM, the numerical simulations were performed to investigate the interaction effects between two identical bodies. For the more reality, the coupled analysis for the FPSO-shuttle tanker model in the tandem arrangement was carried out in the consideration of the environmental condition of the West Africa Sea as a rather mild condition. Through the case studies with interaction effect and without interaction effect by the iteration method and the combined method, it is verified that the program is a very useful tool for the analysis of the interaction problem of multiple-body system and the coupled problem of the hull/mooring/riser.

• 해양환경안전학회지
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• 제29권7호
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• pp.980-991
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• 2023

항만 내 선박과 부두의 사고를 예방하기 위하여 통항 및 접안 안전성 평가를 통하여 안전한 부두가 건설되어 관리하고 있으나, 선박의 접안 및 계류 과정에서 선박이 부두에 충돌하거나 로프로 인한 인명사고의 발생 등 예측할 수 없는 사고들이 종종 발생한다. 자동계류장치는 선박의 신속하고 안전한 계류를 위한 자동화된 시스템으로 로봇 매니퓰레이터와 흡착 패드로 구성된 탈/부착 메커니즘을 가지고 있다. 본 논문은 자동계류장치의 흡착 패드의 위치 및 속도제어에 필요한 선체와의 변위 및 속도 측정 시스템을 다룬다. 자동계류장치에 적합한 측정 시스템을 설계하기 위하여, 본 논문은 우선 센서의 성능 및 실외 환경적 특성 분석을 수행한다. 다음으로 이러한 분석 결과를 토대로 실외 부두환경에서 설치되는 자동계류장치에 적합한 변위 및 속도 측정시스템의 구성 및 설계 방법에 대해 기술한다. 또한 센서의 측정상태 감지 및 속도 추정을 위한 알고리즘을 제시한다. 제안된 방법은 다양한 속도 구간에서의 변위 및 속도 측정 실험을 통해 그 유용성을 검증한다.

• 한국해양공학회지
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• 제29권2호
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• pp.143-153
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• 2015

This paper presents the results of an experimental study on the motion of an FPSO (Floating production storage and off-loading) and the characteristics of the mooring systejavascript:confirm_mark('abe', '1');m according to the turret position. Model tests of a turret-moored FPSO were carried out in the Ocean Engineering basin of KRISO. The FPSO was moored using an internal turret and catenary mooring. The models (1/60 scale) that were prepared included the FPSO, turret, and mooring lines. The experiments were conducted in irregular waves and combined environments, with waves, currents, and winds. A time-domain simulation was performed using OrcaFlex. The motion response and mooring line tension from the present calculations were compared with the results of experiments, and the agreement was fairly good. In addition, the results showed that the weathervaning stability was improved when the position of the turret was moved in the bow direction.

• 대한조선학회 특별논문집
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• 대한조선학회 2013년도 특별논문집
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• pp.97-102
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• 2013

As the offshore oil and gas upstream industry moves into deeper water, the FPSOs are the cost-effective solution. In the harsh environment such as in North Sea, station keeping and heading control capability obtained through the DP and Position Mooring (DPM) system of FPSOs play important roles to keep the safety. This paper introduces the concept, function and sub-system of the DPM systems which has been applied for the North Sea FPSOs since the late 1980s. The requirements and guidelines of some internationally recognized standards are also described, which are important to build the design basis at the early phases of the project.

• 한국해양공학회지
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• 제10권1호
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• pp.92-99
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• 1996

Longline type aquaculture facilities are being used for scallpop culture in 30 m of water 2.5 km off the coast of Joomoonjin, Kangwon-do. In this paper, the facilities are modeled by the cabele-buoy-weight system, subject to the nonlinear behaviors of the mooring lines and the effects of current. Its static configuration is shown as a solution of 3-D nonlinear static equation and Runge-Kutta $4^{th}$ method is employed.

• 한국해양공학회지
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• 제26권6호
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• pp.1-6
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• 2012

The purpose of this paper is to present a rational method for analyzing, designing, or evaluating the spread mooring systems used with floating drilling units. This paper presents a validated model to calculate the catenary static configuration. A semi-resolution approach is presented in this paper that is capable of predicting the static performance of a caisson mooring system. The solution is derived as a function of only three parameters, which can be solved numerically by implementing different kinds of boundary conditions. The efficiency and accuracy of the method permit quick parametric studies for the optimal selection of the system particle, which is undoubtedly useful for a preliminary design. A number of numerical examples demonstrate the validity of the adopted approach. The paper contains a complete description of the test cases and reports the results in such a way that it can provide a "benchmark" test for users and programmers of computer codes for flexible riser analysis.