• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.121-134
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• 1999

In this paper, a ship calculation program is developed, which prof[nuts hydrostatics and volume calculation intact and damage stability and hull variation. Hull form and compartment geometry are expressed with NURBS curve wire-frame model. Hydrostatics and volume calculation are performed directly with the intersection method between section geometry and 3D planar surface. Equilibrium ship position is calculated with hydrostatic equilibrium equation which is linearized by 1st order Taylor series expansion sequentially. The developed program shows more accurate results and easy uses than the latter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.725-734
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• 2009

Maxwell stress tensor is one of the methods which are generally used for electromagnetic force calculation. In this paper, it is presented that Maxwell stress tensor T and n${\cdot}$T have no physical meaning and therefore should not be used as sources of mechanical force for deformations or dynamics. The divergence of Maxwell stress tensor ${\nabla}{\cdot}T$ is the one which can acquire a physical identity and is electromagnetic body force density by an action at a distance like a gravity. This result can be derived from the principle of power balance, and also verified by some thought experiments. The virtual air-gap approach is proposed as a valid solution for the calculation of the body force.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.2
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• pp.35-42
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• 1998

Marine casuality causes not only loss of lives and ships, but also severs damages to marine environment and related economic activities such as fishing industry, sea farming, and tourist industry. Basically, the great effort should be made to prevent the occurrence of maritime accidents by any means. However, once accident has occurred, the salvage works should be done rapidly and properly based on theoretical and technical informations, which could minimize the risk during salvage operation and the overall damage from the maritime accidents. Generally, to calculate accurate hydrostatics of a stranded ship, a large amount of input data is needed. But, an availability and a reliability of input data cannot be guaranteed in most situations, and the adequate time required for preparing all input data is not allowed to perform the timely operations of salvage. In this paper, the development process of simple computer program for salvage operation using limited input data is introduced and its application example is presented. This program was developed to provide technical support for planning salvage operations in the grounding accident.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.43-48
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• 2013

In this paper, magnetic buoyancy force on nonmagnetic solid object submerged in magnetic liquid was simulated and measured. For the evaluation of the force, a multi-physics approach of hydrostatic equilibrium considering magnetic body force as well as gravity is presented. The magnetic body force should be regarded as an additional forcing term in the momentum equation of hydrodynamics. It is also shown that the virtual air-gap based Kelvin's force formula is a useful method for the calculation of force distribution in the magnetic liquid. The experimental result which was performed by a load-cell measurement system agreed quantitatively well with the numerical one.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.863-870
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• 2023

Ship capsize accidents are common in coastal waters, particularly involving small fishing boats. To prevent there overturing accidents in small fishing boats, their stabilities must be assessed at the initial design step. However, the available information during the initial design step is limited, posing challenges in performing a reliable stability evaluation. Therefore, this study presents a plan to estimate the transverse metacenter (GM) of small fishing boats using parameters such as KM, KG, and TRIM that can be determined at the initial design step. Stability was evaluated by comparing GM with the minimum transverse metacenter (GMmin) specified in the standard safety evaluation criteria for fishing boats. To calculate the required trim value for hydrostatic characteristics using K-SHIP, a stability assessment program provided by the Korea Maritime Safety and Transportation Corporation, the initial trim state is estimated based on the ship lines using the commercial CFD program STAR-CCM+. GM is then calculated by assessing the hydrostatic characteristics in relation to the boat lines using K-SHIP. Furthermore, the stability of the fully loaded state is compared by subtrcating GM from GMmin. One constructed ship is designated as the standard ship, and the stability assessment method proposed in this study is applied to evaluate stability and validate its effectiveness. Consequently, the representative line of a 4.99-ton fishing boat and nine modular lines models derived from it were evaluated, ultimately identifying a relatively superior stability.

• Korean Journal of Computational Design and Engineering
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• v.21 no.1
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• pp.90-98
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• 2016

When ships and offshore plants are flooded or the floating crane is equipped with a heavy object, these floating structures are excessively inclined. In this case, immersion, heel, and trim affecting the hydrostatic restoration performance are very large and are coupled each other. In this paper, in order to calculate a static equilibrium position of floating structures with excessive inclination, the nonlinear governing equations were constructed by sequential linearization. In the governing equation, the immersion, heel, and trim are fully coupled, and the equations are represented using a plane area, a primary moment, and a moment of inertia of the water plane area. Therefore, it is possible to calculate the additional factor related the water plane area for estimating stability. Position and orientation of the floating structure are obtained by iterative calculation. The calculated results are compared with the previous studies in the aspect to the performance and the accuracy.