• 한국해양공학회지
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• 제30권6호
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• pp.468-473
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• 2016

This paper focuses on the estimation of local ice loads exerted from ship-ice interaction processes. The Korean IBRV ARAON was used to perform field ice trials during her 2015 Arctic voyage. During ARAON's general ice transit, a total of 72 channels of data from both strain gauges on the inner hull plates and those installed on the transverse frames of the ARAON's bow section structures were analyzed to calculate the local ice loads. The local ice loads estimated from the analysis of the shear strain data measured on the side frames were compared to those from the hull plate pressures.

• 대한금속재료학회지
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• 제50권6호
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• pp.427-432
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• 2012

This paper presents the material properties of carbon steels for ships, and offshore structures (ASTM A131) are tested under a series of arctic and cryogenic temperature conditions. For material tension tests, among the ASTM 131 steels, Grades A and B of mild steel and Grade AH of high tensile steel have been used. The obtained mechanical properties of the materials from the material tension tests were applied in a 13,000TEU class container ship to define the effect of low temperature on the ultimate longitudinal strength of the target structure by using the ALPS/HULL intelligent supersize finite element method. The tensile coupon test results showed increased strength and nonuniform fracture strain behaviors within different grades and temperatures. Increasing the material strength resulted in increasing the ultimate longitudinal strength of the ship.

• 한국해양공학회지
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• 제9권2호
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• pp.156-166
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• 1995

Regrading the development of offshore natural gas field near Sakhalin Island which is an ice-infested area, this study aims to estimate the dynamic ice load for construction of offshore structures operating in this region. In this paper the design ice load and dynamic responses of a slender Arctic structure upon continuous ice movement are sutdied. Crushing agter a certain elastic deformation is assumed as a primary failure mechanism at the contact zone between semi-infinite level ice edge and the face of structure. Dynamic interaction forces are calculated using a modified Korzhavin's equation and a two-dimensional ice-structure interaction model is adopted. To verify the numerical model, dynamic analysis is performed for on of the Baltic Sea channel markers whose response patterns were presiously observed.

• 한국해양공학회지
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• 제7권2호
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• pp.162-172
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• 1993

In the present paper, the overall state of the arts of ice mechanics which is the most typical research topic of the artic engineering field was studied. And also, ice loads genrated by ice-structure interaction were estimated using numerical approach. The effects of viscous property of ice sheets to the ice load were investigated. The time dependent deformation behaviors of ice was modeled by visco-plastic problem using the finite element formalism. Constitutive model representing the material properties of ice was idealized by comblned rheological model with Maxwell and Voigt models. Numerical calculations for the bending and crushing behavior of ice sheet which are the most typical interaction modes between ice sheets and structures were carried out. The time dependent viscous behaviors of ice sheets interaction forces acting on structures were analyzed and the results were studied in detail.

• 대한조선학회논문집
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• 제57권2호
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• pp.80-87
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• 2020

As the Arctic sea ice decreases due to various reasons such as global warming, the demand for ships and offshore structures operating in the Arctic region is steadily increasing. In the case of sea ice, the anisotropy is caused by the uncertainty inside the material. For most of the research, nevertheless, estimating the ice load has been treated deterministically. With regard to this, in this paper, a four-point bending strength analysis of an ice specimen was attempted using a stochastic finite element method. First, spatial distribution of the material properties used in the yield criterion was assumed to be a multivariate Gaussian random field. After that, a direct method, which is a sort of stochastic finite element method, and a sensitivity method using the sensitivity of response for random variables were proposed for calculating the probabilistic distribution of ice specimen strength. A parametric study was conducted with different mean vectors and correlation lengths for each material property used in the above procedure. The calculation time was about ten seconds for the direct method and about three minutes for the sensitivity methods. As the cohesion and correlation length increased, the mean value of the critical load and the standard deviation increased. On the contrary, they decreased as the friction angle increased. Also, in all cases, the direct and sensitivity methods yielded very similar results.

• World Technopolis Review
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• 제6권1호
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• pp.3.1-3.15
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• 2017

Given the diverse environmental contexts of universities worldwide there is a need for a theoretical orientation that addresses the entrepreneurial university in a range of settings. Applying the institutional perspective this research explores how universities are strongly influenced by, as well as active influencers in, their surrounding environment. To do this, we examine case narratives of two universities in each of the following countries: Norway, Sweden, Finland, the UK, and the U.S. Analysis focuses on five entrepreneurial dimensions as defined by Nelles and Vorley (2010a): Structures, Systems, Leadership, Strategies, and Culture while examining the impact of regional and national context at regulative, normative, and cognitive levels of analysis. We address two research questions: How do universities interact with their institutional context in developing entrepreneurially and what actors and forces are most important in motivating institutional change in developing a university's entrepreneurial architecture?

• 한국해안해양공학회지
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• 제1권1호
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• pp.87-92
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• 1989

극지에서의 충돌 빙하중의 크기를 구하기 위해 지반, 구조 및 구조물을 일체로 하는 동적 모델을 제시하였다. 지반은 감쇠 효과를 고려한 비선형 스프링으로 이상화하였으며, 부빙과 구조물의 상호작용은 얼음의 특성을 고려한 비선형 스프링으로 이상화하였다. 이 모델에 의한 여름과 겨울의 부빙의 질량과 속도에 따른 영향을 모래지반과 시일토지반에 대해 각각 해석하여 에너지 평형 방법과 비교하였다. 해석 결과 모래지반의 경우는 대체적으로 에너지 평형 방법에 의한 값이 동적 모델에 의한 값보다 작게 나타났으며, 시일 토지반의 경우는 그 반대로 나타났다.

• 한국해양공학회지
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• 제36권4호
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• pp.232-242
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• 2022

This study presents a method for level ice-structure interaction analysis to estimate the fatigue damage of arctic structures by applying plate theory to the behavior of level ice. The boundary element method (BEM), which incurs a lower computational cost than the finite element method (FEM), was introduced to solve the plate bending problem. The BEM formulation was performed by applying the BEM to plate theory. Finally, to check the validity of the proposed method, the BEM results and FEM results obtained using the ABAQUS commercial software were compared. The response results of the BEM analysis agreed well with those of the FEM analysis. Based on the results of the analysis, the BEM approach is considered to be very powerful in level ice-structure interaction analysis for estimating level ice-induced fatigue damage. Further work is being conducted to perform level ice fracture analysis based on the stress field calculated using the boundary element method.

• 한국미생물·생명공학회지
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• 제44권2호
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• pp.171-179
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• 2016

최근 빙하의 융해로 인해 빙하 해안지역에 다양한 토양 미생물과 초목들이 드러나고있다. 본 연구에서는 북극 스발바르 군도 중앙로벤 빙하 해안 지역으로부터 Ion Torrent Personal Genome Machine(PGM)을 활용한 메타지놈 분석을 통해 세균(bacteria), 고균(archaea), 및 진핵생물(eukaryotes)를 포함하는 다양한 미생물 군집을 분석하였다. 연구에 사용된 토양시료는 빙하 후퇴에 따른 토양의 노출 시기에 따라 2개 지역(ML4 및 ML7)으로부터 수집하였다. ML4 및 ML7 시료의 메타지놈 염기서열을 기반으로 총 2,798,108 및 1,691,859 reads가 각각 미생물 군집 분석에 활용되었다. Domain (계) 수준에서 미생물 군집의 상대 빈도를 분석한 결과 2개 시료 모두 세균(86−87%)이 높은 반면 고균과 진핵생물은 1% 미만으로 존재하는 것으로 나타났다. 또한 약 12%의 염기서열은 기존에 분류되지 않은(unclassified) 서열로 분석되었다. 세균의 경우 Proteobacteria(40.3% for ML4 and 43.3% for ML7)와 Actinobacteria(22.9% and 24.9%)가 우점하는 것으로 분석되었다. 고균의 경우에는 Euryarchaeota(84.4% and 81.1%) 및 Crenarchaeota(10.6% and 13.1%), 그리고 진핵생물의 경우에는 Ascomycota(33.8% and 45.0%)가 우점하는 것으로 분석되었다. 본 연구를 통해 Ion Torrent PGM 플랫폼을 활용한 메타지놈 분석이 북극의 중앙로벤 빙하 해안 지역의 전체 미생물 군집 구조를 파악하는데 충분히 적용될 수 있을 것으로 사료된다.

• 해양환경안전학회지
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• 제23권1호
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• pp.40-46
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• 2017

본 연구는 LS-DYNA 971 을 이용하여 내빙 구조 선박과 빙산 모형 간의 충돌 시험을 수행 후 북극해 운항 선박의 내빙 능력을 분석하였다. 국제선급연합회(IACS)의 Unified Requirements for Polar ship(URI) 규정을 바탕으로 FEM 선박 모형에 내빙 구조를 적용하였으며, 빙산 모형에는 Elastic-perfect plastic 물성과 Tsai-Wu 항복 곡면을 적용하였다. 또한 실험 결과 비교를 위하여 내빙 구조를 갖추지 않은 일반선박 모형과의 충돌 시험도 수행하였다. 실험 결과 일반 구조 선박의 구형 선수에 빙산 모형에 의해 움푹 들어간 약 1.8 미터 깊이의 선체 손상이 발생하였으나, 내빙 구조 선박의 충돌에서는 약 1.0 미터 깊이의 선체 손상만이 발생하였다. 또한 일반 구조 선박과 충돌한 빙산모형은 원형의 상태를 거의 유지한 반면, 내빙 구조 선박과 충돌한 빙산 모형은 내빙 구조의 구형 선수에 의해 빙산이 일부 파괴되는 현상이 발견되었다.