• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.667-679
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• 2020

As the LNG carrier operates in ice covered waters, it is key to ensure the overall safety, which is related to the coupling effect of ice-breaking process and internal liquid sloshing. This paper focuses on the sloshing simulation of the ice-breaking LNG carrier, and the numerical method is proposed using Circumferential Crack Method (CCM) and Volume of Vluid (VOF) with two main key factors (velocity νx and force Fx). The ship motion analysis is carried out by CCM when the ship navigates in the ice-covered waters with a constant propulsion power. The velocity νx is gained, which is the initial excitation condition for the calculation of internal sloshing force Fx. Then, the ship motion is modified based on iterative computations under the union action of ice-breaking force and liquid sloshing load. The sloshing simulation under the LNG tank is studied with the modified ship motion. Moreover, an ice-breaking LNG ship with three-leaf type tank is used for case study. The internal LNG sloshing is simulated with three different liquid heights, including free surface shape and sloshing pressure distribution at a given moment, pressure curves at monitoring points on the bulkhead. This present method is effective to solve the sloshing simulation during ice-breaking process, which could be a good reference for the design of the polar ice-breaking LNG carrier.

• Journal of Ocean Engineering and Technology
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• 제25권1호
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• pp.49-55
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• 2011

The EG/AD/S model ice, originally developed by Timco (1986), was selected as the primary model ice material for the newly built MOERI Ice Model Basin in Korea. However, the existence of a sugar component in the EG/AD/S mixture may cause a serious maintenance problem, as described in certain references. This study focuses on the tests of the mechanical properties of the EG/AD/S and the EG/AD model ice. In order to understand the influence of sugar in the original EG/AD/S model ice and to find a possible substitute for sugar, a series of tests with the EG/AD model ice were performed, and the results were compared to those of the EG/AD/S model ice. The relatively large size of the MOERI Ice Model Basin made it difficult to control the initial strength of model ice, so it took a much longer time to achieve the target strength. In order to obtain a lower strength and stiffness for the model ice, the amount of chemical additives may be varied to achieve the desired strength level. This paper is a preliminary study aimed at seeking a possible substitute for the original EG/AD/S model ice for utilization in a large-scale ice tank. To understand the influence of sugar in the original EG/AD/S model ice, the mechanical properties of the EG/AD/S and EG/AD model ice, such as flexural strength, compressive strength, and elastic modulus, were tested in the laboratory condition and compared to each other. The warm-up procedure seems to be an important factor to reduce ice strength in the tests, so it is discussed in detail.

• Journal of Ocean Engineering and Technology
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• 제33권6호
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• pp.556-563
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• 2019

The ice keel gouge and seabed interaction is one of the major considerations in the design of an Arctic pipeline system. Ice keel and seabed interaction engineering models based on experimental data, which give an explicit equation for estimating the ice gouging depth, have been suggested. The suggested equations usually overestimate the ice keel gouging depth. In addition, various types of numerical analyses have been carried out to verify the suggested engineering model equations in comparison to the experimental data. However, most of numerical analysis results were also overestimated compared with the laboratory experimental data. In this study, a numerical analysis considering the contact condition and geostatic stress was carried out to predict the ice keel gouging depth and compared with the previous studies. Considering the previously mentioned conditions, more accurate results were produced compared with the laboratory experiment results and the error rate was reduced compared to previous numerical analysis studies.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권3호
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• pp.110-117
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• 2006

Ice adhesion or cohesion leads to the decrease of the performance of ice making system, especially to dynamic type ice thermal storage system (DISS) which mainly forms ice from the flow of an aqueous solution. The ice adhesion is influenced by various parameters associated with operating or geometric condition. In this study, the influence on an adhesion of ice to the characteristic of cooling surface and to composition of an aqueous solution was fundamentally observed by using batch type cooling device,. a beaker. Three patterns of solution in each beaker were cooled with brine. Moreover, the characteristic of cooling surface on each beaker was distinguished to coating materials. Stirring power as a degree of the ice adhesion was measured. The stirring power to cooling heat transfer rate in each beaker was compared. As a result, the lowest stirring power of 8.9 W with non-adhesion of ice, was shown in the case of the aqueous solution of EG(4) + PG(1.5) + 1,6HD(1.5). in PE coating beaker.

• Journal of Ocean Engineering and Technology
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• 제32권3호
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• pp.177-183
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• 2018

This study simulated ice load and the motion response of a moored semi-submersible rig in pack-ice conditions using a finite element method. Ice flows of random size and shape were modeled, and interactions for ice-sea, ice-structure, ice-ice were simulated using a simplified method. Parameters for the simplified method such as drag force coefficient and the pressure-penetration relation were obtained based on the result of detailed analysis using the coupled Eulerian-Lagrangian method. The mooring lines were modeled by spring elements based on their stiffness. As a result of the simulation over 1,400 seconds, the force and motion response of the rig were obtained and validated using discrete elements and compared with the results found by the Krylov State Research Centre.

• Journal of Industrial Technology
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• 제26권B호
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• pp.63-71
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• 2006

The concerned object of the construction industry is environment. It is one of the main purposes of today's construction that human can live reasonably in nature. This study is about the fish-road connecting hydraulic structure in the river with nature. Chapter 2, starting with the general investigation about fish-road and helps comprehension for relatively general fish-road such as necessity, establishment purpose, history, study example, relating domestic law, design condition, consideration and form of fish-road. Chapter 3, containing the present condition of fish-road facilities in Gangwon-Do and thoughts of the problems and general countermeasures of existing fish-road. Chapter 4, Having Examined compatibility by amount of flowing water through hydraulic model test in the Ice harbor I-type model. chapter 5, Analyzation and arrangement to efficient establishment plan of fish-road and the result of the hydraulic model experiment to be beaconed a little in forward fish-road study. In the hydraulic model test result, when we suppose establishment of 1~3 in slope of 1/20, could know that applicable drought flow of the river is $0.06{\sim}3.0m^3/sec$ in case of Ice harbor I-type which transforming Ice harbor that was invented as studying project of the Ministry of Environment.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권1호
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• pp.116-131
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• 2013

The resistance performance of an icebreaking cargo vessel in pack ice conditions was investigated numerically and experimentally using a recently developed finite element (FE) model and model tests. A comparison between numerical analysis and experimental results with synthetic ice in a standard towing tank was carried out. The comparison extended to results with refrigerated ice to examine the feasibility of using synthetic ice. Two experiments using two different ice materials gave a reasonable agreement. Ship-ice interaction loads are numerically calculated based on the fluid structure interaction (FSI) method using the commercial FE package LS-DYNA. Test results from model testing with synthetic ice at the Pusan National University towing tank, and with refrigerated ice at the National Research Council's (NRC) ice tank, are used to validate and benchmark the numerical simulations. The designed ice-going cargo vessel is used as a target ship for three concentrations (90%, 80%, and 60%) of pack ice conditions. Ice was modeled as a rigid body but the ice density was the same as that in the experiments. The numerical challenge is to evaluate hydrodynamic loads on the ship's hull; this is difficult because LS-DYNA is an explicit FE solver and the FSI value is calculated using a penalty method. Comparisons between numerical and experimental results are shown, and our main conclusions are given.

• Journal of the Society of Naval Architects of Korea
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• 제56권3호
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• pp.217-230
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• 2019

In this study, a fatigue damage estimation for an ice-going vessel navigating through broken ice fields was carried out. A numerical model to simulate the interaction between ice and structure developed using the finite element method was introduced. Time series of stresses calculated by the proposed model and the corresponding fatigue analysis results are presented. The numerical model enables the long time analysis through an efficient interaction model, the application of the periodic media analysis and the convolution integral, and it allows the stress time history to be extracted directly using the finite element method. To describe the probability distribution of stress amplitudes, the 2-parameter Weibull model was applied to the calculated stress time history, and the fatigue damage was calculated using the Palmgren-Miner rule. Finally, the fatigue damage considering the ice conditions of the Baltic Sea was calculated using the proposed method and LR method, and the results were compared to each other.

• Proceedings of the SAREK Conference
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.533-538
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• 2005

The number of domestic ice-rink is little by little increasing recently. Therefore, the demand for air-conditioning system to adjust adequately the indoor condition of ice-rink is constantly increasing. But, if air-conditioning system for ice-rink isn't designed properly, the problems such as fogging, ice surface condensation, structural deterioration, odors, generation of dew condensation on the surface of a wall occur. The solutions for these problems are to lower the relative humidify of indoor. The objectives of this paper is to apply of desiccant dehumidifier on ice-rink, solve these problems.

• Journal of Wind Energy
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• 제5권1호
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• pp.43-49
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• 2014

Primarily, tower loads of a wind turbine arise from aerodynamic effect and a top head mass. But sometime asymmetric loads of rotor also affect on the tower loads. Especially ice formation on two blades out of three causes the asymmetric loads, because the ice formation on blades lead to large rotating mass imbalance. This rotating mass imbalance of rotor affects tower fatigue loads. So design load cases of ice formation on blade should be considered in the fatigue design loads of the tower according to GL guideline 2010. This paper describes the change of tower fatigue loads following increase of tower height in the condition of ice formation. Finally, the optimal operation strategy is examined in order to reduce tower fatigue design loads.