• Journal of Advanced Marine Engineering and Technology
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• 제37권7호
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• pp.718-728
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• 2013

Analysis of scenarios of transportation oil and gas which produced in the Arctic and others cold seas shows that in the near-term there will be a significant increase of tonnage of tankers for oil and gas and number of ships which should be exploited in difficult ice conditions. For the construction of ice-resistant structures (IRS) intended for production of oil and gas and transportation of these products at ice-class vessels, calculating the load from ice to board the ship and on surface of supports of the platforms are the actuality and urgent tasks. These tasks have one basis in both cases: at beginning of the contact occurs fracture of edge of ice, then occurs compressing of rubble shattered of ice, then they extruding from contact area, after this next layer of ice begin to destruct. At calculating the strength of plating and elements construct of vessels, icebreakers and ice-resistant platforms the specific energy of mechanical destruction ice ${\epsilon}_{cr}$ is an important parameter. For the whole period of study of physical and mechanical characteristics of sea ice have been not many experimental studies various researchers to obtain numerical values of this energetic characteristic of the strength of ice by a method called Ball Drop Test. This study shows that the destruction of the ice from dynamic loading in zone of contact occurs in several cycles, and the ice destructed with a minimum numerical values of ${\epsilon}_{cr}$. The author offer this energy characteristic to take as a base value for the calculation of ice load on ships and offshore structures.

• 한국해양공학회지
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• 제32권6호
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• pp.411-418
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• 2018

This paper introduces a new method of ice load generation in the time domain for the station-keeping performance evaluation of Arctic offshore structures. This method is based on the ice load spectrum and mean ice load. Recently, there has been increasing interest in Arctic offshore technology for the exploration and exploitation of the Arctic region because of the better accessibility to the Arctic ocean provided by the global warming effect. It is essential to consider the ice load during the development of an Arctic offshore structure. In particular, when designing a station-keeping system for an Arctic offshore structure, a consideration of the ice load acting on the vessel in the time domain is essential to ensure its safety and security. Several methods have been developed to consider the ice load in the time domain. However, most of the developed methods are computationally heavy because they consider every ice floe in the sea ice field to calculate the ice load acting on the vessel. In this study, a new approach to generate the ice load in the time domain with computational efficiency was suggested, and its feasibility was examined. The ice load spectrum and mean ice load were acquired from a numerical analysis with GPU-event mechanics (GEM) software, and the ice load with the varying heading of a vessel was reconstructed to show the feasibility of the proposed method.

• 한국해양공학회지
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• 제33권2호
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• pp.161-167
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• 2019

This paper focuses on a newly designed ice load formula based on the ARAON's 2016 Arctic field data in order to improve a structural design against ice loads. The strain gage signals from ARAON's hull plating were converted to the local ice pressure upon the hull plating using the influence coefficient matrix and finite element analysis. First, a traditional pressure-area relationship is derived by applying probabilistic approaches to handle the strains measured onboard the ARAON. Then, the local ice load prediction formula is re-analyzed after reviewing the ARAON's additional field data to consider information about the ship speed and thickness of the sea ice. It is shown that the newly developed pressure-area relationship well reflects the influence of other design parameters such as the ship speed and ice thickness in the prediction of local ice loads on Arctic vessels.

• 대한조선학회논문집
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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.

• 한국지구과학회지
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• 제36권2호
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• pp.139-157
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• 2015

본 연구에서는 위성관측 표면온도 및 해당 온도경향의 불확실성을 조사하기 위하여 북반구($30-90^{\circ}N$) 해양 지역에서 2003-2014년 4월 16-24일 기간에 세 종류의 위성관측 자료(MODIS IST, AIRS/AMSU SST, AIRS only SST)를 상호 비교하였다. AIRS/AMSU 표면온도값에 비하여 MODIS는 해빙과 해수의 경계지역에서 계통적으로 최대 1.6 K 높은 반면에, 해빙 지역에서는 2 K 낮았다. 이러한 주요 원인은 표면온도 산출알고리즘의 해표 정보(e.g., 해빙 탐지)를 위하여 MODIS는 적외 채널만을 사용하는 반면에, AIRS/AMSU는 마이크로파 및 적외 채널을 함께 사용하는 데에 있다. 미국 항공우주국(NASA's Goddard Space Flight Center; NASA/GSFC)은 AMSU-A의 노후화를 대비하기 위하여 AIRS/AMSU 알고리즘을 일부 수정하여 AIRS only 알고리즘을 개발하였다. AIRS/AMSU와 AIRS only 표면온도 사이에 평균 제곱근 오차(RMSE)값은 $30-90^{\circ}N$ 해양 지역에서 0.55 K이며, 편차(bias)는 0.13 K이었으며, 해빙/해수 경계 지역에서는 이들 차이가 더 크게 나타났다. 해빙 경계지역에서 AIRS/AMSU와 AIRS only 간의 차이가 다른 지역에 비하여 큰 이유는 AIRS only 알고리즘이 AMSU 마이크로파 자료 대신에 GCM (NOAA Global Forecast System) 온도 산출물을 사용하는 데에 있다. 세 종류의 위성관측 표면온도 자료는 $70-80^{\circ}N$ 위도대에서 유의적인 온도증가($0.23-0.28Kyr^{-1}$)를 보였다. 위성관측 표면온도들 간에 계통적인 불일치는 같은 방향(온도증가 또는 온도감소)으로 해당 온도경향 값들 간의 차이에 영향을 줄 수 있다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권3호
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• pp.376-384
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• 2018

Selection of suitable ice class for ships operation is an important but not simple task. The increased exploitation of the Polar waters, both seasonal periods and geographical areas, as well as the introduction of new international design standards such as Polar Code, reduces the relevancy of using existing experience as basis for the selection, and new methods and knowledge have to be developed. This paper will analyse what can be the limiting ice thickness for ships navigating in the Russian Arctic and designed according to the Finnish-Swedish ice class rules. The permanent deformations of ice-strengthened shell structures for various ice classes is determined using MT Uikku as the typical size of a vessel navigating in ice. The ice load in various conditions is determined using the ARCDEV data from the winter 1998 as the basic database. By comparing the measured load in various ice conditions with the serviceability limit state of the structures, the limiting ice thickness for various ice classes is determined. The database for maximum loads includes 3-weeks ice load measurements during April 1998 on the Kara Sea mainly by icebreaker assistance. Gumbel 1 distribution is fitted on the measured 20 min maximum values and the data is divided into various classes using ship speed, ice thickness and ice concentration as the main parameters. Results encouragingly show that present designs are safer than assumed in the Polar Code suggesting that assisted operation in Arctic conditions is feasible in rougher conditions than indicated in the Polar Code.

• 한국전산구조공학회논문집
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• 제27권5호
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• pp.353-360
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• 2014

본 논문에서는 국내 선박해양플랜트연구소에 구축된 빙해수조의 빙특성 중에서 모형빙의 두께와 유효탄성계수 산출과정이 소개되었다. 수조에서 결빙되는 빙판은 크기가 가로 세로각각 30 m 정도에 두께는 40mm정도이다. 모형선의 실험결과를 쇄빙선 설계에 사용하기 위하여 빙 특성 정보가 필요하다. 사람이 빙판을 일부 절개하고 일일이 손으로 두께를 측정하는 것을 지양하기 위하여 초음파 기기를 사용하였는데 저주파 장비를 사용하여 작은 샘플 모형빙에 대한 두께는 계측되었다. 하지만 완벽한 계측을 위해서는 송수신 일체형 저주파 센서나 정확한 위치가 설정된 분리형 센서 혹은 고가의 특수 장치가 필요함을 확인하게 되었다. 한편 빙판의 처짐량을 간이식 LVDT로 계측하고 이를 탄성체 위에 놓인 무한 판의 특성길이 관계식에 대입하여 빙의 유효탄성계수를 산출하였는데 외국의 결과와 유사함이 입증되었다.

• 한국해양공학회지
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• 제30권4호
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• pp.303-309
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• 2016

As commercialization of the Arctic sea route and resource developments are regularized, demands for ice-breaking tankers, LNG carriers, and offshore plants are expected to increase. In addition, the existing ice-breaking cargo ships navigating in the ice-covered waters are worn out. Hence, the construction of new ships is likely to be undertaken for both current and long-term applications. The design of ships navigating in ice-covered waters demands conservative methods and strict development standards owing to the extreme cold and collision tendencies with ice floes and/or icebergs. ISO 19906 recently stated that a fatigue limit should be defined when designing Arctic offshore structures such that the ice-induced fatigue becomes one of the important design drivers. Thus, establishing systematic measures to mitigate ice-induced fatigue problems in ice-breaking ships are important from the viewpoint of having a competitive advantage. In this paper, the issues relating to ice-induced fatigue problems, based on data and published literature, are examined to describe the criticality of ice-induced fatigue. Potential fatigue damage possibilities are investigated using data measured in the Arctic Ocean (2013) and using the Korean icebreaker, ARAON.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2009년도 춘계학술대회 논문집
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• pp.143-146
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• 2009

다산기지 주변 해역인 스발바드섬은 북반구 해빙 분포지역의 가장자리에 위치해 있으며 해빙의 이동이 비교적 빠른 지역이다. 지구 온난화의 영향을 받는 대표적인 지역으로 이 지역의 해빙변화에 대한 연구는 지구온난화의 지표로서 중요성을 가진다. 스발바드섬 주변의 해빙에서 얻어진 다편파 SAR 데이터를 분석하여 해빙에 대한 후방산란계수의 특성을 분석하고자 한다. 데이터 획득에는 ENVISAT/ASAR (2002 년 발사 C-밴드, 다편파 사용)과 PALSAR (2006 년 발사, L-밴드, 다편파 사용)의 두 가지 SAR 가 이용되었으며 데이터 획득 시기는 해빙의 변화가 활발한 4 월경이다. 기본적으로 L-밴드와 C-밴드의 두 가지 밴드별 차이에 관한 특성을 알아보고 기타 후방산란계수에 영향을 주는 요소들에 대하여 알아보고자 한다.

• Ocean and Polar Research
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• 제41권2호
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• pp.63-77
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• 2019

In order to investigate the behavior and seasonal variability of Mn as one of the bio-essential metals in the Amundsen sea, which is known as the most biologically productive coastal area around the Antartica, seawaters were collected using a clean sampling system for 10 stations (96 ea) in 2014 (ANA04B) and for 12 stations (139 ea) in 2016 (ANA06B) surveys of RV ARAON. Dissolved and particulate Mn concentration varied in the range of 0.15-4.43 nmol/kg and <0.01 to 2.42 nM in 2014 and in the range of 0.25-4.15 nmol/kg and 0.01-2.64 nM in 2016, respectively. From the sectional distribution of dissolved and particulate Mn, it might be suggested that dissolved/particulate Mn was provided from iceberg melting and diffusion/resuspension from sediments, respectively. Although this sea is highly productive, there was little evidence regarding the biological origin of dissolved Mn, but particulate Mn only in sea ice and offshore areas could be explained as originating from organic matters, e.g. phytoplanktons. And it could be suggested that the subsurface maximum of dissolved Mn was formed by isopycnal transport of melting materials from ice wall to offshore. Compared to early (2014) summer, temperature, salinity, biomass, dissolved and particulate Mn in late (2016) summer indicated that temporal variations might be resulted from the reduction of ice melting and mCDW flow, which induced a reduction in resuspension. In addition, in the late summer, particles including biomass were reduced, which brought about a reduction in the removal rate of dissolved Mn.