• Title/Summary/Keyword: Pack ice

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Development of Model Test Methodology of Pack Ice in Square Type Ice Tank (사각 빙해수조에서의 Pack Ice 모형시험 기법 개발)

  • Cho, Seong-Rak;Yoo, Chang-Soo;Jeong, Seong-Yeob
    • Journal of the Society of Naval Architects of Korea
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    • v.48 no.5
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    • pp.390-395
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    • 2011
  • The main purpose of ice model basin is to assess and evaluate the performance of the Arctic ships and offshore structures because the full-scale tests in ice covered sea are usually very expensive and difficult. There are various ice conditions, such as level ice, brash ice, pack ice and ice ridge, in the real sea. To estimate their capacities in ice tank accurately, an appropriate model ice sheet and prepared ice conditions copied from actual sea ice conditions are needed. Pack ice is a floating ice that has been driven together into a single mass and a mixture of ice fragments of varying size and age that are squeezed together and cover the sea surface with little or no open water. So Ice-class vessels and Icebreaker are usually operated in pack ice conditions for the long time of her voyage. The most ice model tests include the pack ice test with the change of pack ice concentration. In this paper, the effect of pack ice size and channel breadth in pack ice model test is conducted and analyzed. Also we presented some techniques for the calculation of pack ice concentration in the model test. Finally, we developed a new model test methodology of pack ice condition in square type ice tank.

Study on the procedure to obtain an attainable speed in pack ice

  • Kim, Hyun Soo;Jeong, Seong-Yeob;Woo, Sun-Hong;Han, Donghwa
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.4
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    • pp.491-498
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    • 2018
  • The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

An Algorithm for Measurement of Pack Ice Concentration Using Localized Binarization of Quadtree-Subdivided Image (쿼드트리 분할영상의 국부이진화를 통한 팩아이스 집적도 측정 알고리즘)

  • Lee, Jeong-Hoon;Byun, Seok-Ho;Nam, Jong-Ho;Cho, Seong-Rak
    • Journal of the Society of Naval Architects of Korea
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    • v.54 no.1
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    • pp.49-56
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    • 2017
  • Recently, many research works on the icebreaking vessels have been published as the possibility of passing Arctic routes has been increasing. The model ship test on the pack ice model in the ice basin is actively carried out as a way to investigate the performance of icebreaking vessels. In this test, the concentration of pack ice is important since it directly affects the performance. However, it is difficult to measure the concentration because not only the pack ice has uneven shape but also it keeps floating around in the basin. In this paper, an algorithm to identify the concentration of pack ice is introduced. From a digital image of pack ice obtained in the ice basin, the goal is to measure the area of pack ice using an image processing technique. Instead of the general global binarization that yields numerical errors in this problem, a local binarization technique, coupled with image subdivision based on the quadtree structure, is developed. The concentration results obtained by the developed algorithm are compared with the manually measured data to prove its accuracy.

Numerical and Experimental Investigations of the Effects of Stem Angle on the Resistance of an Icebreaking Cargo Vessel in Pack Ice Conditions

  • Shin, Yong Jin;Kim, Moon Chan;Kim, Beom Jun
    • Journal of Advanced Research in Ocean Engineering
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    • v.2 no.2
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    • pp.67-80
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    • 2016
  • The resistance performance of an icebreaking cargo vessel with varied stem angles is investigated numerically and experimentally. Ship-ice interaction loads are numerically calculated based on the fluid structure interaction (FSI) method using the commercial FE package LS-DYNA. Test results obtained 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 icebreaking cargo vessel with three stem angles ($20^{\circ}$, $25^{\circ}$, and $30^{\circ}$) is used as the target ship for three concentrations (90%, 80%, and 60%) of pack ice conditions. The comparisons between numerical and experimental results are shown and our main conclusions are given.

Numerical and experimental investigation of the resistance performance of an icebreaking cargo vessel in pack ice conditions

  • Kim, Moon-Chan;Lee, Seung-Ki;Lee, Won-Joon;Wang, Jung-Yong
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.1
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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.

Comparative study on the resistance performance of an icebreaking cargo vessel according to the variation of waterline angles in pack ice conditions

  • Kim, Moon-Chan;Lee, Won-Joon;Shin, Yong-Jin
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.4
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    • pp.876-893
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    • 2014
  • The resistance performance of an icebreaking cargo vessel according to the variation of waterline angles is investigated numerically and experimentally. A recently developed Finite Element (FE) model is used in our analysis. A resistance test with synthetic ice is performed in the towing tank at Pusan National University (PNU) to compare and validate the computed results. We demonstrate good agreement between the experimental and numerical results. Shipice interaction loads are numerically calculated based on the Fluid Structure Interaction (FSI) method in the commercial FE package LS-DYNA. Test results from model testing with synthetic ice at the PNU towing tank are used to compare and validate the numerical simulations. For each waterline angle, numerical and experimental comparisons were made for three concentrations (90%, 80%, and 60%) of pack ice. Ice was modeled as a rigid body, but the ice density was the same as that used in the experiments. A comparative study according to the variation of stem angles is expected to be conducted in the near future.

A Study on Resistance Test of Icebreaker with Synthetic Ice (합성 얼음을 사용한 쇄빙선 저항시험에 대한 연구)

  • Song, Yun-Young;Kim, Moon-Chan;Chun, Ho-Hwan
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.4
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    • pp.389-397
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    • 2007
  • This research describes a framework to compare and analyze the icebreaker(Terry Fox) resistance in pack ice condition between with a refrigerated ice and a synthetic ice. Model tests with a refrigerated ice have been conducted at Institute for Ocean Technology (IOT/NRC) and the tests with a synthetic ice were conducted at Pusan National University towing tank. For the validation of further tests of measurement and accuracy, the open water tests were first carried out with same model ship to compare the test results of both Institutes. Two different size of the wax-type synthetic ice were used and tests were conducted in pack ice of three different concentration ice conditions. The test results show that the difference of resistance between with synthetic and with refrigerated ice becomes larger according to the increase of ship speed. Although the quantity of resistance difference is not so small in high speed range, the present study is predicted to be used as a useful correlation between synthetic and refrigerated ice.

북극항로 운항 선박의 빙해역 운항 속도 추정에 관한 연구

  • Kim, Hyeon-Su;Han, Dong-Hwa;Ozden, Ali Erinc
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2018.11a
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    • pp.177-180
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    • 2018
  • As ships operating on the Arctic route are exposed to various ice environments such as level ice, pre-swan, pack ice, ice ridge and brash ice, it is essential to estimate the ice resistance according to the ice environment. Methods for estimating the ice resistance include a method using mathematical model, numerical simulation, and a method using empirical formula. In this study, empirical formulas are used to estimate the ice resistance. The purpose of this study is to develop the ice resistance and attainable speed estimation program(I-RES) for various ice environments.

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Study on Resistance Performance of Icebreaking Cargo Vessel in Pack Ice Condition according to Variation of Synthetic Ice Thickness and Hull Form Characteristics (합성얼음의 두께변화와 선형변화에 따른 Pack ice 상태에서의 쇄빙상선의 저항특성 연구)

  • Lee, Seung-Ho;Kim, Moon-Chan;Chun, Ho-Hwan;Cho, Jun-Cheol;Shin, Byung-Chul;Jung, Un-Hwa
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.5
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    • pp.471-478
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    • 2009
  • The present paper deals with characteristics of resistance performance according to the variation of synthetic ice thickness and hull form. The resistance test has been conducted with pack ice condition in Pusan National University towing tank. Stem angle has been chosen as main parameters for the variation of hull form characteristics, which is the most important factor especially in icebreaking cargo vessel. The serial comparisons of resistance test have been done with the variation of hull form parameter as well as with the different thickness of synthetic ice. The different trend of resistance performances with increasing of stem angle has been shown at each synthetic ice thickness. The present test results is expected to be confirmed by comparing the test results in ice tank in the near future.

Comparison Study on the Resistance Characteristics of an Arctic Tanker and a General Tanker (쇄빙 유조선과 일반 유조선의 저항특성 비교연구)

  • Kim, Hyun-Soo;Ha, Mun-Keun;Ahn, Dang;Chun, Ho-Hwan
    • Journal of the Society of Naval Architects of Korea
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    • v.43 no.1 s.145
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    • pp.43-49
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    • 2006
  • The hull form of icebreaking tanker depends on the trade route and ice characteristic. The hull form has to be designed for icebreaking concept if the vessel is operating in heavy ice and also the hull from has to be optimized for general tanker when the ship is operating in ice-free ocean. This paper presents comparison of ship resistance in pack ice, level ice and open water. Four ships are used to compare the resistance characteristic. One is conventional tanker and three ships are icebreaking tankers. The ice model test was carried out at the IOT (Institute for Ocean Technology, Newfoundland, Canada) and open water test was performed at 55MB (Samsung Ship Model Basin). The ice resistance of conventional tanker was predicted by Colbourne's method. The resistance of open water, pack ice and level ice are compared and discussed. The best hull form of icebreaker is not good in open water performance compare to conventional tanker. This result explains that the hull form of icebreaker and normal tanker have to compromise when the ship is operated in ice and ice-free condition. The result of this paper gives a guide for icebreaking tanker design.