• Title/Summary/Keyword: Ocean-based approach

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A novel multistage approach for structural model updating based on sensitivity ranking

  • Jiang, Yufeng;Li, Yingchao;Wang, Shuqing;Xu, Mingqiang
    • Smart Structures and Systems
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    • v.25 no.6
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    • pp.657-668
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    • 2020
  • A novel multistage approach is developed for structural model updating based on sensitivity ranking of the selected updating parameters. Modal energy-based sensitivities are formulated, and maximum-normalized indices are designed for sensitivity ranking. Based on the ranking strategy, a multistage approach is proposed, where these parameters to be corrected with similar sensitivity levels are updated simultaneously at the same stage, and the complete procedure continues sequentially at several stages, from large to small, according to the predefined levels of the updating parameters. At every single stage, a previously developed cross model cross mode (CMCM) method is used for structural model updating. The effectiveness and robustness of the multistage approach are investigated by implementing it on an offshore structure, and the performances are compared with non-multistage approach using numerical and experimental vibration information. These results demonstrate that the multistage approach is more effective for structural model updating of offshore platform structures even with limited information and measured noise. These findings serve as a preliminary strategy for structural model updating of an offshore platform in service.

Extended pivot-based approach for bilingual lexicon extraction

  • Seo, Hyeong-Won;Kwon, Hong-Seok;Kim, Jae-Hoon
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.5
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    • pp.557-565
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    • 2014
  • This paper describes the extended pivot-based approach for bilingual lexicon extraction. The basic features of the approach can be described as follows: First, the approach builds context vectors between a source (or target) language and a pivot language like English, respectively. This is the same as the standard pivot-based approach which is useful for extracting bilingual lexicons between low-resource languages such as Korean-French. Second, unlike the standard pivot-based approach, the approach looks for similar context vectors in a source language. This is helpful to extract translation candidates for polysemous words as well as lets the translations be more confident. Third, the approach extracts translation candidates from target context vectors through the similarity between source and target context vectors. Based on these features, this paper describes the extended pivot-based approach and does various experiments in a language pair, Korean-French (KR-FR). We have observed that the approach is useful for extracting the most proper translation candidate as well as for a low-resource language pair.

Overview of Chlorophyll-a Concentration Retrieval Algorithms from Multi-Satellite Data

  • Park, Ji-Eun;Park, Kyung-Ae;Park, Young-Je;Han, Hee-Jeong
    • Journal of the Korean earth science society
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    • v.40 no.4
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    • pp.315-328
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    • 2019
  • Since the Coastal Zone Color Scanner (CZCS)/Nimbus-7 was launched in 1978, a variety of studies have been conducted to retrieve ocean color variables from multi-satellites. Several algorithms and formulations have been suggested for estimating ocean color variables based on multi band data at different wavelengths. Chlorophyll-a (chl-a) concentration is one of the most important variables to understand low-level ecosystem in the ocean. To retrieve chl-a concentrations from the satellite observations, an appropriate algorithm depending on water properties is required for each satellite sensor. Most operational empirical algorithms in the global ocean have been developed based on the band-ratio approach, which has the disadvantage of being more adapted to the open ocean than to coastal areas. Alternative algorithms, including the semi-analytical approach, may complement the limits of band-ratio algorithms. As more sensors are planned by various space agencies to monitor the ocean surface, it is expected that continuous monitoring of oceanic ecosystems and environments should be conducted to contribute to the understanding of the oceanic biosphere and the impact of climate change. This study presents an overview of the past and present algorithms for the estimation of chl-a concentration based on multi-satellite data and also presents the prospects for ongoing and upcoming ocean color satellites.

Force Equilibrium-Based Safety Assessment System for Cargo Securing of Car Ferries

  • Kim, Younghun;Choung, Joonmo;Jo, Huisang;Lee, Kyounghoon
    • Journal of Advanced Research in Ocean Engineering
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    • v.2 no.3
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    • pp.112-128
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    • 2016
  • Capsize and sinking of a coastal car ferry has occurred in a Korean offshore area and has caused hundreds of human casualties. The rapid turn and improper cargo loading are inferred as the main reasons of the accident. It has motivated to develop a new system of cargo securing with improved safety of Korean coastal ferries. This paper provides a new approach regarding cargo securing safety assessment which is purely based on force equilibrium conditions, because IMO CSS is suitable for the ocean-going vessels. The mathematical formulations are presented for the new approach. This paper also introduces a newly developed safety assessment system based on the new approach. Most outstanding features are that it can utilize acceleration data produced from hydrodynamic motion analyses or assumed maximum extents of ship motion components and that securing safety assessment is simultaneously possible for unlimited number of cargoes with finite number of lashings.

Adaptive Learning Path Recommendation based on Graph Theory and an Improved Immune Algorithm

  • BIAN, Cun-Ling;WANG, De-Liang;LIU, Shi-Yu;LU, Wei-Gang;DONG, Jun-Yu
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.5
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    • pp.2277-2298
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    • 2019
  • Adaptive learning in e-learning has garnered researchers' interest. In it, learning resources could be recommended automatically to achieve a personalized learning experience. There are various ways to realize it. One of the realistic ways is adaptive learning path recommendation, in which learning resources are provided according to learners' requirements. This paper summarizes existing works and proposes an innovative approach. Firstly, a learner-centred concept map is created using graph theory based on the features of the learners and concepts. Then, the approach generates a linear concept sequence from the concept map using the proposed traversal algorithm. Finally, Learning Objects (LOs), which are the smallest concrete units that make up a learning path, are organized based on the concept sequences. In order to realize this step, we model it as a multi-objective combinatorial optimization problem, and an improved immune algorithm (IIA) is proposed to solve it. In the experimental stage, a series of simulated experiments are conducted on nine datasets with different levels of complexity. The results show that the proposed algorithm increases the computational efficiency and effectiveness. Moreover, an empirical study is carried out to validate the proposed approach from a pedagogical view. Compared with a self-selection based approach and the other evolutionary algorithm based approaches, the proposed approach produces better outcomes in terms of learners' homework, final exam grades and satisfaction.

Considering Concepts and Principles of Marine Spatial Management for Sustainable Use of Marine Resources (지속가능한 이용을 위한 해양공간관리의 개념과 원칙에 대한 고찰)

  • Lee, Moon-Suk
    • Ocean and Polar Research
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    • v.33 no.4
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    • pp.497-506
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    • 2011
  • The rapid industrial and technological development has made the human activities for the utilization of marine resources more complex. Marine spatial management is a space-based approach. It is a comprehensive and integrated management approach. The ultimate goal of marine spatial management is the "sustainable use" of marine resources. The partial approach is applied in the existing marine spatial management, mainly coastal zones which involves integrated approach. Also this showed various limitations including restricted mostly to coastal zones, and limitation to implementation tools. However, for marine spatial management to have a reasonable approach that attaches importance to the relationship between humans and the holistic ecosystem, it is important to internalize a central principle in marine spatial management that focuses on the sustainable use of marine resources. In the present study, four central principles are proposed that will eventually be applied through marine spatial management planning tools. These principles are 1) the establishment of a cooperative decision making and planning system that is based on stakeholder participation; 2) scientific assessment of the current status and impact on the basis of ecology, sociology, and economics; 3) reasonable and optimal spatial assignment based on the forecasting of future-use characteristics and environmental changes; and 4) ascribing importance to the implementation of the results of rational planning processes.

Fatigue Analysis of 306K Crude Oil Tanker Based on MSC Fatigue

  • Guo, Wei;Bae, Dong-Myung;Cao, Bo;Qi, Da-Long
    • Journal of Ocean Engineering and Technology
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    • v.29 no.6
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    • pp.463-469
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    • 2015
  • Fatigue in the metal used as hull material has always been an important issue. The fatigue phenomenongenerally occurs suddenly in a ship hull, and always causesa large number of casualties and economic losses. This paper presents a study of an assessment method for the fatigue life based on Li’s approach using MSC Fatigue. The details of Li’s approach based on MSC Fatigue are provided. Based on the results of this study, it can be concluded that Li’s approach has several advantages: (1) it allows the wide application of different structural details, (2) is easy to use, and (3) provides accurate results. Finally, Li’s approach can be proven to be feasible for a ship’s fatigue analysis.

An Approach for Construction of Shipyard Simulation Environment based on Neutral File Format (중립파일 기반의 조선소 시뮬레이션 환경에 관한 연구)

  • Woo, Jong Hun;Hwang, Yoon-Suk;Nam, Jong-Ho
    • Journal of the Society of Naval Architects of Korea
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    • v.53 no.1
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    • pp.18-28
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    • 2016
  • In shipbuilding, the scheduling system is susceptible to sudden changes and thus it turns to be difficult to predict the differences between schedule and production records in advance. A computer-based simulation is commonly utilized to overcome the discrepancies occurred in estimating workloads and resulting processing times. The main drawback of this simulation-based solution is its limited applicability because, in most cases, each shipyard requires specific and customized simulation environment. By standardizing the planning data of the midterm scheduling system, as proposed in this paper, the efficiency of the current simulation model can be enhanced. To present an alternative approach, this paper begins with the analysis of the complex planning data structure of several shipyards and then proceeds to construct a standard data structure based on the neutral format. An interface application is developed for the data transaction and simulation in on-line environment. As a result, a simulation-based production management of shipyards can be achieved by the efficient prediction of planning and scheduling.

International Trends of Ocean-based Climate Actions as a Solution for Climate Crisis : Focused on Integrated Approach and Multi-Benefits (기후위기 해결책으로서 해양기반기후행동을 위한 국제적 논의동향에 대한 소고 : 통합적 접근과 상호혜택 증진을 중심으로)

  • Sora Yun;Yinhuan Jin
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.7
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    • pp.740-749
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    • 2023
  • The ocean plays a vital role in the international carbon cycle, absorbing human-induced atmospheric carbon and preventing further atmospheric carbon accumulation. However, while the ocean had been considered a victim of climate change, it did not receive much attention as a solution for climate change in the major agenda of UNFCCC. Recently, a growing awareness that the ocean can provide numerous potentials to handle untapped issues to address the climate crisis has arisen, which has prompted discussions to strengthen ocean-based climate action. Since 2020, UNFCCC "Ocean and climate change dialogue" has been a forum to integrate and strengthen the ocean-climate nexus. This calls for integrating ocean action into climate action and the relevant sectors. In this regard, this study examined the background and international trends of ocean-based climate action and presented the author's perspective on the scope of content that such action should pursue and the direction to achieve it. In addition, this study identified tasks of the integrated approach and advancement of co-benefit as ways to strengthen ocean-based climate action, and it suggested domestic countermeasures for the Korean marine policy on climate change based on this.

A study on the ecosystem-based management system for fisheries resources in Korea (생태계 차원에서의 수산자원관리 방안 연구)

  • Zhang, Chang-Ik
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.42 no.4
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    • pp.240-258
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    • 2006
  • The potential of ecosystem-based fisheries management is recently recognized to be very important to improve the sustainability of fisheries resources. Under the depressed condition of many fisheries resources, this recognition has been expanded and more effort has been taken to improve this approach. Taking ecosystem concept includes the use of other tools of management in addition to fisheries regulation, such as stock and productivity enhancement, provision of physical structure, or marine protected areas. In the ecosystem-based fisheries management approach, it would require to holistically consider ecological interactions of target species with predators, competitors, and prey species, the effects of climate on fisheries ecology, the complex interactions between fishes and their habitat, and the effects of fishing on fish stocks and their ecosystem. Fisheries management based upon the understanding of these factors can prevent significant and potentially irreversible changes in marine ecosystems caused by fishing. A useful approach for analyzing tropho-dynamic interactions and mass-balance in marine ecosystems is introduced to demonstrate the complexity and usefulness of the ecosystem approach, which was applied to a small ecosystem in Korea. Korea should seriously consider to take the ecosystem-based approach to fisheries management, since most major fish stocks are currently depleted due to many reasons such as overfishing, land reclamation and coastal pollution.