• Journal of the Korean Institute of Navigation
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• v.11 no.2
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• pp.73-88
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• 1987

It is well known that the height of tank metacenter above the centroid of fluid in a tank is given by i/v where I is the inertia moment of free surface and v is the fluid volume. It is supposed in this formula that the inclination of ship is small and that the free surface of fluid do not touch the top and the bottom of tank. It the inclination of ship is large, the height of tank metacenter may be possibly greater than that given by i/v. The height of tank metacenter is smaller than i/v when the free surface of fluid touch the top or the bottom of tank. The reasonable method to calculate the height of tank metacenter is presented in this paper and prepared in FORTRAN program by FUNCTION EFFRES. The approximate formula was also developed and given by $g_m=(1+\frac{2}{1}tan^2\theta)[1-EXP\{-12(\frac{\alpha(1-\alpha)k}{tan\theta})^{1.25}\}]\frac{i}{v}$ where $g_m$ is the distance from the centroid of fluid to the tank metacenter, $\theta$ is inclined angle of ship, $\alpha$ is the ratio of filled volume to tank capacity and k is the ratio of the depth to the width of tank. The values calculated by the approximate formula given in this paper were compared with the exact values from the computer program and proved out to be sufficiently precise for practical use.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1003-1004
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• 2012

• Journal of Korean Port Research
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• v.14 no.1
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• pp.77-86
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• 2000

The planning process of complex projects in oceanic architectural engineering is characterized by the cooperation of many involved specialists and by a high degree of information exchange. In order to improve the quality of the structural design of oceanic buildings, information of different involved partners in the planning process has to be integrated. This paper aims to introduce a concept of the integrated structural design for the floating-type oceanic building using STEP(Standard for the Exchange of Product Model Data). STEP(ISO 10303) is an international standard for the computer-interpretable representation and exchange of product data and it provides a consistent data exchange format and application interfaces between different application systems. In this paper, the structural design process and information of oceanic buildings is analyzed and product models are preposed fir the exchange of the structural design information between superstructure and floating structure. The entities for calculating wind loads, metacenter and restoring forces are represented by Express. As a case study a floating hotel is applicated to describe the STEP physical file.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.2
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• pp.45-55
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• 1999

The majority of fishing vessels(under 20 tonnages) in Korea have a high casualty accident of the flood and capsizing occurred by lack of stability. Actually, it is so difficult to make out the data of inclining and stability tests of small fishing vessels after building, because most of them were built on experiences of manufacturer. According to above reasons, the aim of this study is an attempt to propose a stability criteria of small fishing vessels as follows: Firstly, it is examined that the stability is driven from a transverse metacenter height of actual ships, which is able to obtain a basic drawing and stability data. Secondly, it is examined the heeling at high-speed turning, and the period of rolling according to B/D(breadth/depth). Finally, it is suggested the stability criteria by using a dynamic state which is applied in passenger boat and fishing vessels over 24 meters.

• 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.

• Journal of Navigation and Port Research
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• v.43 no.5
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• pp.328-334
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• 2019

Underwater architecture in providing a comfortable living space underwater is mandated to survive prevailing environmental loads, especially hydrostatic ambient water pressure exerted on the structure of individual habitat hulls at depth and hydrodynamic fluctuation of external forces that perturb the postural equilibrium and mooring stability of the underwater housing system, for which the design including the hull shape and mooring system constraint the responses. In this study, the postural stability of a proposed underwater floating housing system with three vertically connected ellipsoidal-shape habitat hulls of different sizes are theorized and calculated for hydrostatic stability, using MATLAB in the volumetric integration of a hull and the weight of operational loads under assumed scenarios. The assumptions made in the numerical method to estimate the stability of the habitat system include the fixed weight of the hulls, and their adjustable loads within operational limits for the set meteorological oceanic conditions. The purpose of this study was to numerically manipulate a) The buoyancy and b) The adjusted center of mass of the system within the range of designed external and internal load changes, by which the effective mooring system capability and postural equilibrium requirements were argued with the quantitative analysis.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.623-632
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• 2014

In this study, the stability of fishing vessels get some change in accordance with the installation of LED luring lamp in comparison with metal halide luring lamp were investigated. Inclining test for 9.77 ton class of squid jigging and hair-tail angling vessel was performed in order to make a stability evaluation. A performance analysis of the target vessels to the stability on the basis of KST-SHIP program was evaluated. The results were as follows in this study. The stability of the fishing vessel by a metal halide such as LED and the like according to the result obtained by the inclining test is a slightly present difference, and the stability is not affected. The fishing vessel with LED lamp installed satisfies all the stability criteria specified in law and IMO rule. Compared to the metal halide LED lamp the increase of the height of the center of gravity and the initial transverse metacenter was caused. Due to the LED installation, the somewhat wider wind area of the waterline, which appears as a result, does not lead to an actual increase in rolling period. But then it is necessary to be designed on that the LED lamp shape reduces wind pressure area. Because of LED lamp installation, the GM value of vessels is increasing faster rolling cycle so causes a decrease in the sense that the crew is aboard.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.654-659
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• 2016

Recently, the passenger ship 'Sewol' capsized with an abrupt inclination while she was making a small angle alteration. It is very important to fully understand the concepts, causes and relevant corrections for a ship's transverse inclination, which is classified into heel, list and loll. In this study, the concept, development and calculation of loll were well considered and the actual magnitude of the angle of loll was simulated in a box-shaped model-ship experiment. The experimental values and its development according to different values of negative stability were compared with calculated values. In the results, experimental values for the angle of loll coincided closely with calculated values and the model inclined symmetrically on both port and starboard sides indicating an outstanding feature of loll. This study is expected to expand the concept of loll and help in the analysis of capsize incidents with unknown causes. Further experimental research or case studies concerning the risk of inappropriate correction for loll arising from misunderstandings will be needed.