Lee, Sang Chul (Korea Maritime and Ocean University ) | Park, Sunho (Korea Maritime and Ocean University ) | Choi, Kyungsik (Korea Maritime and Ocean University ) | Jeong, Seong-Yeob (Korea Research Institute of Ships and Ocean Engineering ) | Seo, Young Kyo (Korea Maritime and Ocean University )
This study predicted global ice loads on a hull of an icebreaker with inertial measurement system method which treated the ship as a rigid body and measured whole ship motions. The calculation of the global ice load was based on the data measured by full-scale ice sea trials of Korean ice breaking research vessel 'ARAON' during her arctic ocean voyage in 20l5. To calculate the maximum global ice load, two methods, i.e. the point of impact (POI) approach and the center of gravity (COG) approach, were used, respectively, and the results were compared with the empirical ice load estimation formula under normal operating conditions.
Kwon, Yong-Hyeon (Gyeongsang National University) | Lee, Jong-Hyun (Gyeongsang National University) | Choi, Kyungsik (Korea Maritime and Ocean University) | Lee, Tak-Kee (Korea Maritime and Ocean University)
In summer 2010, field measurements of local ice loads were carried out in the Arctic Ocean using the Korean first icebreaking research vessel, ARAON. In some previous studies by the authors, several investigations for the data measured at 2010 including the relationship between the measuring points and ice loads, the possibility for observation of higher ice load and the relationship between the ship speed and ice loads were reported. During 10 days in August 2013, new field measurements were performed in similar waters of the Arctic Ocean using the same vessel, ARAON. The aim of this study is to investigate the statistical properties of 2013 measurements and compare results by two periods.
This study presents the analysis of relationship between ship speed and local ice load on the Korean Icebreaker ARAON. The relationship curves were made from the data obtained at two areas: the Arctic and the Antarctic; and for two operation condition: the icebreaking condition in sea ice trial and general operation in ice covered sea. The strain data were converted to the equivalent stress value, and the influence of ship speed on the local ice load was analyzed and compared each other. These analysis results are useful in working on a statistically valid hull design approach.
Shin, Jang-Ryong (Daewoo Shipbuilding and Marine Engineering Co. Ltd Geoje, Korea) | Han, Ik Seung (Daewoo Shipbuilding and Marine Engineering Co. Ltd Geoje, Korea) | Choi, Kyungsik (Korea Maritime University Busan, Korea) | Kang, Sin-Young (Korea Maritime University Busan, Korea)
In most of the wave theories, a boundary value problem consisting of a partial differential equation and certain boundary conditions describing the various boundaries is solved in an approximate way. The complete boundary value problem has not been solved, even in the simple case of constant water depth. The theory developed in this paper is limited to a flat bottom having a constant water depth. The waves are assumed regular. Water is considered as incompressible and inviscid as with most of the wave theories. Therefore the continuity equation which gives rise to the basic differential equation of wave motion is Laplace equation. In this paper, an ordinary differential equation which is equivalent to Laplace equation with the non-linear boundary conditions, is introduced for developing a 3-dimensional gravity wave theory. General solutions satisfying Laplace equation, bottom boundary condition and non-linear kinematic boundary condition on free surface are developed. By applying the general solutions to non-linear dynamic boundary condition on free surface, an ordinary differential equation is derived. The ordinary differential equation gives rise to eigen value problem. The eigen values of the equation are dispersion relationship. To verify the validity of the ordinary differential equation, it is proved that the general solutions developed in this paper include Dean''s solution which was developed using stream function theory.
Numerous water wave theories have been developed which are applicable to different environments dependent upon the specific environmental parameters, e.g., water depth, wave height and wave period. Airy wave theory, Stokes wave theory, Cnoidal wave theory , Solitary wave theory and Dean’s numerical stream function theory are commonly used in the design of offshore structure(Chakrabarti, 1987; DNV, 2007). For high Ursell numbers the wave length of the Cnoidal wave goes to infinity and the wave is a solitary wave(DNV, 2007).
Cho, Seong-Rak (Maritime & Ocean Engineering Research Institute, KORDI Daejeon, Korea) | Lee, Chun-Ju (Maritime & Ocean Engineering Research Institute, KORDI Daejeon, Korea) | Jeong, Seong-Yeob (Maritime & Ocean Engineering Research Institute, KORDI Daejeon, Korea) | Kim, Jung-Hyun (Department of Ocean Engineering, Korea Maritime University Busan, Korea) | Choi, Kyungsik (Department of Ocean Engineering, Korea Maritime University Busan, Korea)
One of the tasks when evaluating the performances of ice class vessels and Arctic offshore structures in an ice model basin is to prepare a proper model ice which shows correct similitude with natural sea ice. Every ice model basin in the world has individually developed the ice modeling technique and methodology to assist their adaptation. The EG/AD/S model ice which is a diluted aqueous solution of ethylene glycol, aliphatic detergent and sugar, may provide for the correct scaling of mechanical properties of columnar sea ice. The MOERI(Maritime & Ocean Engineering Research Institute) ice model basin of Korea scheduled to open in 2009, adopts the EG/AD/S type model ice, with a collaboration of the IOT(Institute for Ocean Technology), Canada. This study focuses on the evaluation of mechanical properties of EG/AD/S type model ice for possible use in the new MOERI ice model basin. Before completion of the new ice model basin, instead of using actual ice model basin, a cold room facility was used for making model ice growth and measuring its mechanical properties. The warm-up technique applied for the model ice growth seems to be most important factor to reduce ice strengths in this test. It was reported that the sugar component in the model ice solution may cause a difficult maintenance problem due to organic bacteria. Hence the influence of sugar component on the original EG/AD/S model ice was tested to check the possible removal of sugar from the original EG/AD/S solution.
Recent dramatic change in energy prices and the global warming trend accelerate the development of Arctic/sub-Arctic regions and also enhance the activities in the Arctic seas. Especially, the exploration of natural resources and their transportation through the Northern Sea Route made it possible to reduce the operation cost and to derive new design concepts of ship and offshore structure.
One of the widely-used ice resistance prediction methods, introduced by Spencer(1992) of Canada, is reviewed. Spencer''s component-based scaling system for ship-ice model test is analyzed to estimate the ice resistance of various types of icebreaking vessels (Canadian MV Arctic, Terry Fox, R-class, US icebreakers Polar Star and Healy, Russian SA-15 cargo ships, Japanese PM Teshio and one model ship). The general form and the non-dimensional coefficients in ice resistance prediction formula are obtained using the published ice model test and full-scale sea trial data. The applicability of Spencer''s method for the larger icebreaking cargo vessels is discussed.
Resistance is related to propulsion of a ship and it determines the engine power requirement of the ship. Estimation of ship’s resistance in ice-covered sea has been a very interesting topic to shipbuilders. There have been many theoretical approaches to estimate the resistance but it is not yet sufficient to say that there is a universally accepted method of predicting ice resistance of ship because ship-ice interaction and icebreaking process are very complicated. In this study, as an effort to find a proper ice prediction formula for icebreaking vessels, especially for large cargo vessels, the ice resistance prediction method, introduced by Spencer of Canada (Spencer, 1992; Spencer and Jones, 2001) is reviewed. Spencer''s component-based scaling system for ship-ice model test is one of the widely-used methods to estimate level ice resistance and was successfully applied to the Canadian R-class icebreaker. In this study Spencer’s ice resistance prediction formula is generalized for various types and sizes of icebreaking vessels such as Canadian MV Arctic, Terry Fox, R-class icebreaker, US icebreakers Polar Star and Healy, Russian SA-15 cargo ships, Japanese PM Teshio and one model ship, and the non-dimensional coefficients in ice resistance prediction formula are obtained using the published ice model test and full-scale sea trial data.