• Smart Structures and Systems
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• 제25권6호
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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.

• Journal of Advanced Marine Engineering and Technology
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• 제38권5호
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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.

• 한국지구과학회지
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• 제40권4호
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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.

• Journal of Advanced Research in Ocean Engineering
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• 제2권3호
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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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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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.

• Ocean and Polar Research
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• 제33권4호
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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.

• 한국해양공학회지
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• 제29권6호
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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.

• 대한조선학회논문집
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• 제53권1호
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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.

• 해양환경안전학회지
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• 제29권7호
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• pp.740-749
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• 2023

해양은 인간이 발생시킨 대기 중 탄소를 흡수하고 탄소가 대기 중에 더욱 축적되는 것을 방지하는 등 국제 탄소 순환에서 중요한 역할을 하고 있다. 그러나 유엔기후변화협약(UNFCCC) 당사국총회 및 주요 협상의제에서 해양 분야는 기후변화에 의한 희생자로 여겨진 반면, 기후해결을 위한 해결책으로서는 크게 주목받지 못하였다. 최근 해양과 기후시스템이 서로 긴밀하게 연결되어 있고 해양은 기후위기를 해결하기 위해 그 동안 다루지 않았던 수많은 기회를 제공할 수 있다는 인식이 제고되면서, 해양을 기반으로 한 기후 행동을 강화하기 위한 논의를 시작하고 있다. UNFCCC는 2020년부터 해양과 기후변화 이슈를 통합하고 이를 강화하기 위한 논의의 장으로서 '해양대화'를 개최하며, 해양기반기후행동을 강화하기 위한 방안과 도전과제 등을 논의·공유하고 있다. 이와 관련하여 본 연구는 해양기반기후행동에 대한 국제적 논의 배경과 주요 내용을 살펴보고, 해양기반기후행동이 추구해야 하는 내용의 범위와 이를 달성하기 위한 방향에 대한 견해를 제시해보았다. 그리고 해양기반기후행동을 강화하기 위한 방안으로서 통합적 접근과 상호혜택의 증진 등을 위한 과제를 제시하고, 이를 기반으로 국내에서 해양기반기후행동을 강화하기 위한 과제를 제안하였다.

• 수산해양기술연구
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• 제42권4호
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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.