• Journal of the Society of Naval Architects of Korea
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• v.49 no.4
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• pp.304-311
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• 2012

One of the main features of Drillship or FPSO is a moonpool structure. The moonpool structures have various accuracy tolerances according to their functions and targets. This study is mainly interested in roundness of a circular moonpool structure in FPSO. Because this structure needs abrasion-resistance at which bearing of machine touches on inner wall of moonpool, we should do over-lay welding widely and deeply by using Inconel weld material. But a general over-lay can cause a severe distortion at ship block structure. If we can analyze the roundness by thermal distortion under Inconel over-lay, we can establish a special erection policy by the results. In this study, we designed stress-strain curve for strain-boundary condition analysis by an elasto-plastic material property. The results made us to decide an appropriate ship-block size and policy of crane manipulation will follow for its capacity. If a structure that needs over-lay is not large, solid elements also are not a bad choice for FEM modeling. Therefore we also developed a standard of using strain-boundary method that shell elements are used as over-lay on solid element modeling.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.4
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• pp.457-466
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• 2015

In this paper, the academic research on the value chain and the supply chain of offshore business are conducted for the investigation of the offshore business comprehensive configuration. Then, the assembly and ergonomic simulation was conducted for the purpose of advanced validation of offshore project.. With respect to the simulation analysis, the assembly simulation model(w.r.t. drill ship) and the ergonomic simulation model(w.r.t. FPSO) are constructed. Through the assembly simulation of drillship, the production processes could be validated in terms of availability. Also, the problem of topside design of FPSO was found by ergonomic simulation.

• Journal of Power System Engineering
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• v.19 no.1
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• pp.76-82
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• 2015

An analysis model is developed using a commercial software 'simulationX' for designing hydraulic-pneumatic system of heave compensator for offshore drilling operations. Reliability verification of the analysis model for the test equipment of 1/5 scale compensator was conducted by comparing test results and simulation results. An analysis of full scale heave compensator is developed on the basis of verified a model. Then, the results of simulation were analyzed to obtain following conclusion. The displacement of crown block about excitation input amplitude (${\pm}3,000mm$) of the steward platform using a 'simulationX' is attenuated under ${\pm}35mm$, and the compensation rate is 98.7%. In this study, goal of a compensation rate is more than 95%. The previously results are satisfied with the objectives of compensation rate.

• Journal of Ocean Engineering and Technology
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• v.24 no.4
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• pp.53-58
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• 2010

Offshore floater such as FPSO, drillship is composed of topside and hull side, and the interface structure is called topside module support. In this study, practical considerations were investigated for the design of topside module supports, from the concept design stage to the final stage of structural determination, in view of design efficiency and construction productivity. The effects of welding design factors of topside module support, such as welding throat thickness, sectional welding area, and welding man-hours, were compared and analyzed closely with respect to productivity. The current status and problems regarding the application of deep or full penetration welding are discussed, and a direct-calculation method is suggested as a possible solution to these problems.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.5
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• pp.368-377
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• 2017

Outfittings of offshore plants and high value-added vessels, such as FPSO, drillship, are much more than outfittings of general ships. So the complexity of the outfittings is increased and the importance of outfittings has also increased. But, there is no clear method to define the installation sequence of outfittings, yet. In this study, we developed the algorithm to define the installation sequence of outfittings by applying variables and constraints related to outfitting, such as process parameters, weighting coefficients, installation constraints. Also, we developed the application that applied the algorithm and compared cases by changing the weighting coefficients of process parameters. We verified the practicality of the algorithm by developing the application. The results of this study are that the accuracy of the outfitting planning is improved and efficient lead time can be predicted by defining the installation sequence of outfittings.

• Fire Science and Engineering
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• v.26 no.1
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• pp.1-9
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• 2012

Since accommodation, public space and service areas where people stay for all day occupy about 70% of a huge cruise ship, they have to be protected from the fire. International Maritime Organization has resolved that a water mist system should be equipped in this cruise ship according to SOLAS II-2 Reg. 10.6 and FSS code Ch. 7. The water mist system consists of mist nozzles, pressure vessels, section valves and pump unit etc. In particular, the water mist nozzles should be recognized by fire tests in accordance with IMO Res. MSC 265(84). In this study, the fire tests for cabin, corridor, public space and storage area have been conducted to develop the water mist nozzles appropriate to the regulation. Totally 5 types of nozzles were developed and have satisfied the whole performance requirements.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.189-195
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• 2000

New concept of LNG-FPSO ship with moonpool and bilge step in bottom is considered and investigated in the point of motion reduction and sloshing phenomena of the cargo and operation tanks. The cargo capacity of the ship of which principle dimensions is L x B x D x t(design) =270.0 x 51.0 x 32.32 x 13.7(m) 16K at 98% loading condition. The two moonpools and rectangular step at bilge part are setted up specially for getting the effect of motion decrease. For the motion analysis, linearized three dimensional diffraction theory with the simplified boundary conditions is used. The six-degree of freedom coupled motion responses are calculated for the LNG-FPSO ship. Viscous effects on the roll motion responses of a vessel are taken into account in this calculation program using an empirical formula suggested by Ikeda, Himeno and Tanaka is used. The case study for the moonpool size had been carried out by theoretical estimation and experimental method. For the optimization of the moonpool size and effect of the step, 9 cases of its size and with and without step are considered. From the results of calculation and experiment, it can be concluded that this designed LNG-FPSO ship have possibility to carry out her missions in the rough sea as for the owner's demand waves condition. The motion responses, especially roll motion, for the designed LNG-FPSO ship are much lower than those of another drillship and shuttle tanker and limit criterions are satisfied. For the check of the cargo tank and operation tank sizes we have performed sloshing analysis in the irregular waves which focuses on the pressure distribution on the tank wall and the time history of pressure and free surface for No.2 and No5. tanks of LNG-FPSO with chamfers. Finally we got the tank size which has no resonance and no impact pressure in all filling in the bow quartering and beam sea.

• Journal of Ocean Engineering and Technology
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• v.16 no.1
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• pp.1-7
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• 2002

본 논문에서는 선체 하부에 moonpool과 bilge step을 장착한 새로운 개념으의 LNG-FPSO를 운동감소와 cargo, operation tank의 슬로싱 현상의 관점에서 기술하였다. LNG-FPSO의 주요제원은$L\times B\times D\times t(design)=270.0\times51.0\times32.32\times13.7(m)$ 이고 적용조건은 total corgo capacity of 161KT at 98% loading condition 이다. LNG-FPSO의 운동감소의 목적으로 2개의 moonpool과 선체하부 bilge 부분에 사각 step을 장착하였다. LNG-FPSO의 운동해석을 위해 단순화된 경계조건을 만족하는 선형화된 3차원 diffraction theory를 사용하였고 LNG-FPSO의 연성된 6-자유도 운동응답을 계산하였다. LNG-FPSO의 정확한 Roll 운동을 추정하기 위해 점성효과는 Himeno(1981)가 제안한 경험식을 사용하였다. Moonpool의 크기에 따른 운동감소의 경향을 파악하기 위해 이론적 계산과 실험적 방법으로 수행하였다. Moonpool 크기와 bilge step의 효과를 최적화하기 위해 총9가지의 case를 설정하였다. 이론 및 실험 결과로부터 본 LNG-FPSO는 moonpool과 bilge step의 장착으로 인한 감쇠력의 증가로 운동성능이 우수하다. 본 LNG-FPSO의 운동 응답중, 특별히 roll 운동이 다른 drillship, shuttle tanker등의 선박과 비교하여 상당히 작았고 이는 moonpool과 blige step의 장착으로 인한 효과로 판단된다. Cargo tank와 operation tank 크기를 검토 하기 위해 불규칙 해상중 sloshing 해석을 chamfer를 갖는 LNG-FPSO의 No.2, No.5 tank 벽면의 압력 분포와 자유표면의 time history에 초점을 맞추어 수행하였다. 최종적으로 tank 크기를 최적화 하였고 최적화된 tank는 선수사파와 횡파상태의 모든 filling에서 공진현상과 충격압력이 발생하지 않음을 확인하였다.

• Journal of Navigation and Port Research
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• v.38 no.1
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• pp.81-87
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• 2014

Today, it is a trend that the demand of offshore plants is constantly growing, along with the advances in technology which are thoroughly needed to the rise of international oil price as well as offshore energy development. In addition, The main sectors of ship building, sale & purchase and chartering market regarding various kind of offshore supporting vessels that supports the business of offshore energy development is now maintaining its steady growth. However, in domestic case, the contract of time charter occasions regarding the offshore support vessel are almost non-existing situation. Thus, the relevant practical study regarding to implementation of various kinds of legal disputes and applicable laws that can be properly applied in time charter and the field of sale & purchase needs to be conducted actively. Therefore, the concept of this study has included the wide comparisons of other special provisions with the existing time-charter by making its base on "Supply Time 2005" which is the worldwide standard form of time charter in offshore support vessel market and its investigation, aiming to provide practical guidance and procedure for implementation of arbitration and applicable law issues which can be applied in legal disputes between parties.