• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.369-381
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• 2021

The International Ice Patrol (IIP) was established after the Titanic collided with an iceberg off the eastern coast of Canada in 1912 and sank, killing more than 1,500 people. Recently, the IIP has analyzed satellite images and provided safe operation information to vessels by tracking the occurrence and movement of icebergs. A large number of recent arctic studies mainly deal with sea ice formed by freezing seawater related to sea routes and resource development. The iceberg that collided with the Titanic was land-based ice that dislodged from a glacier and fell into the sea. The properties of these two types of ice are different. In addition, vessels operating in ice-covered waters such as the Arctic sea have an ice-breaking function or minimum ice-strengthened functions. Ships operating on transatlantic routes including the eastern coast of Canada do not necessarily require ice-strengthened functions. Hundreds to thousands of icebergs are discovered each year near the area where the Titanic sank. In this study, the status of ship-iceberg collision accidents was investigated to provide useful information to researchers, and the physical and mechanical characteristics of icebergs were investigated and summarized.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1284-1290
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• 2007

This study was conducted to investigate the antibacterial activity and shelf-life extension effect of iceberg lettuce packed in BN/PE film. The BN/PE film has a strong microbial suppression effect on pathogenic bacteria such as Escherichia coli, Salmonella enteritidis, and S. typhimurium. The number of psychrophiles and mesophiles during 5 days of cold storage of fresh-cut iceberg lettuce at $10^{\circ}C$ packaged in BN/PE film was strictly suppressed in comparison with other tested films (OPP, PE, and PET film). When fresh processed iceberg lettuce was processed and stored under the current conditions, the shelf-life of the product was longer than 5 days in the BN/PE film package, whereas the shelf-life when using the other films tested, PE, OPP and PET, was no longer than 3-4 days. The decay rates of the iceberg lettuce packed in the BN/PE film was maintained at $29.8{\pm}2.1%$ on the 5th day of preservation. The samples packed in BN/PE film maintained an excellent visual quality during the 3 days of storage without significant differences in comparison with the initial visual quality. No browning was observed in the samples packed in BN/PE film for up to 3 days. The texture of shredded iceberg lettuce packaged in BN/PE film remained unchanged up to 3 days, and then a moderate decrease in texture was observed after 4 days of storage. In addition, the overall acceptability of fresh-cut iceberg lettuce packaged in BN/PE film did not change for up to 3 days, whereas the samples packaged in the other films were inedible by 3 days of storage. In conclusion, the shelf-life of fresh-cut iceberg lettuce packaged in the BN/PE film was extended to more than 5 days at $10^{\circ}C$, whereas that in the other films was 2 days at $10^{\circ}C$. Therefore, the shelf-life extension effect of the fresh-cut iceberg lettuce in BN/PE film packaging was very effective compared with the other films tested.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.568-572
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• 2008

This study was conducted to investigate the effect of modified atmosphere packaging (MAP) in combination with BN/PE film on the shelf life and quality of fresh-cut iceberg lettuce during cold storage. The total mesophilic population in the sample packed in BN/PE film under MAP conditions was dramatically reduced in comparison with that of PE film, PE film under MAP conditions, and BN/PE film. The $O_2$ concentration in the BN/PE film under MAP conditions decreased slightly as the storage period progressed. The coloration of the iceberg lettuce progressed the slowest when it was packaged in BN/PE film under MAP conditions, followed by BN/PE film, PE film, and PE film under MAP conditions. The shelf life of fresh-cut iceberg lettuce packaged in the BN/PE film under MAP conditions was extended by more than 2 days at $10^{\circ}C$ as compared with that of the BN/PE film in which the extension effect was more than 2 days longer than that of PE, PET, and OPP films.

• Journal of Applied Biological Chemistry
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• v.50 no.4
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• pp.239-243
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• 2007

Effects of aqueous chlorine dioxide ($ClO_2$) treatment on the microbial growth and the quality of iceberg lettuce during storage were examined. Lettuce samples were treated with 0, 5, 10, and 50 ppm of $ClO_2$ solution and stored at $4^{\circ}C$. Aqueous $ClO_2$ treatment significantly decreased the populations of total aerobic bacteria, yeasts and molds, and coliforms on the shredded lettuce. Fifty ppm $ClO_2$ treatment reduced the initial populations of total aerobic bacteria, yeasts and molds, and coliforms by 1.77, 1.34, 1.10 log CFU/g, respectively. Aqueous $ClO_2$ treatment caused negligible changes in the Hunter color L, a, and b values during storage. Sensory evaluations exhibited that there were no significant changes among treatments. These results indicate that the aqueous $ClO_2$ treatment can be useful in improving the microbial safety of the iceberg lettuce during storage and extending the shelf life.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.411-420
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• 2019

It is essential to design crashworthy marine structures for operations in Arctic regions, especially ice-covered waters, where the structures must have sufficient capacity to resist iceberg impact. In this study, a numerical analysis of a colliding accident between an iceberg and stiffened plates was carried out employing the commercial finite element code ABAQUS/Explicit. The ice material model developed by Liu et al. (2011) was implemented in the simulations, and its availability was verified by performing some numerical simulations. The influence of the ambient temperature on the structural resistance was evaluated while the local stress, plastic strain, and strain energy density in the structure members were addressed. The present study revealed the risk of fracture in terms of steel embrittlement induced by ambient temperature. As a result, the need to consider the possibility of brittle failure in a plate-stiffener junction during operations in Arctic regions is acknowledged. Further experimental work to understand the structural behavior in a plate-stiffener junction and HAZ is required.

• Journal of KIISE:Databases
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• v.36 no.3
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• pp.226-234
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• 2009

A data stream is a massive unbounded sequence of data elements continuously generated at a rapid rate. Due to the characteristics of a data stream, it is impossible to save all the data elements of a data stream. Therefore it is necessary to define a new synopsis structure to store the summary information of a data stream. For this purpose, this paper proposes a cuboid prefix tree that can be effectively employed in evaluating an iceberg query over data streams. A cuboid prefix tree only stores those itemsets that consist of grouping attributes used in GROUP BY query. In addition, a cuboid prefix tree can compute multiple iceberg queries simultaneously by sharing their common sub-expressions. A cuboid prefix tree evaluates an iceberg query over an infinitely generated data stream while efficiently reducing memory usage and processing time, which is verified by a series of experiments.

• Journal of The Korean Association For Science Education
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• v.37 no.4
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• pp.611-624
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• 2017

The purposes of this study are to explore Iceberg(IB) model as a systems thinking analysis tool for high school students, suggest a systems thinking analysis method using rubrics and verify its validity and reliability. For this study, the theoretical basis was examined through literature analysis about IB model and rubrics of evaluating the systems thinking. And 6 high school students participated in IB model activity and were interviewed about polar climate change. In addition, quantitative tests using systems thinking scale were also conducted to support the results of the IB model activity analysis. Data obtained from IB model activity was analyzed by using the rubrics of evaluating system thinking developed by Hung (2008). The analysis results were reviewed by two professors to confirm the validity and reliability. In order to confirm the validity, correlation analysis were performed between the rubrics and the quantitative test results. Finding are as follows: Six students used the IB model to express their systems thinking in detail and the results of the systems thinking analysis of students using rubrics showed a distribution of 17~35 points. Furthermore, the results of correlation analysis between rubrics and systems thinking scale was highly correlated (Pearson product-moment is .856) on significance level from .05. Using the IB model introduced in this study, students express their systems thinking effectively and the results of the systems thinking analysis using IB model is considered to analyze validity and reliability. Based on the results of this study, implication suggests how to study the systems thinking in science education.

• Korean Journal of Remote Sensing
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• v.28 no.1
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• pp.21-28
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• 2012

In this study, detection of icebergs that have various scattering characteristics around Wilkinson glacier in West Antarctica is investigated using C-band fully-polarimetric RADARSAT-2 SAR data. Various polarimetric analyses including Freeman-Durden decomposition, H/A/$\bar{\alpha}$ decomposition, entropy (H) and anisotropy (A) method, and Wishart unsupervised classification, were applied for the RADARSAT-2 data used in this study. The polarimetric decomposition methods were successfully classified most of the iceberg, yet some iceberg with similar intensity of volume and surface scattering as sea ice were indistinguishable. Unsupervised classification with a combination of the polarimetric parameter, [1-H][1-A], gave a possibility to distinguish those unclassified iceberg.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.237-243
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• 2020

A novel psychrotolerant Psychrobacillus strain PB01, isolated from an Antarctic iceberg, was comparatively analyzed with five related strains. The complete genome of strain PB01 consists of a single circular chromosome (4.3 Mb) and a plasmid (19 Kb). As potential low-temperature adaptation strategies, strain PB01 has four genes encoding cold-shock proteins, two genes encoding DEAD-box RNA helicases, and eight genes encoding transporters for glycine betaine, which can serve as a cryoprotectant, on the genome. The pan-genome structure of the six Psychrobacillus strains suggests that strain PB01 might have evolved to adapt to extreme environments by changing its genome content to gain higher capacity for DNA repair, translation, and membrane transport. Notably, strain PB01 possesses a complete TCA cycle consisting of eight enzymes as well as three additional Helicobacter pylori-type enzymes: ferredoxin-dependent 2-oxoglutarate synthase, succinyl-CoA/acetoacetyl-CoA transferase, and malate/quinone oxidoreductase. The co-existence of the genes for TCA cycle enzymes has also been identified in the other five Psychrobacillus strains.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.40-46
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• 2017

Shipping activities have become possible in the Arctic Ocean due to melting ice by global warming. An increasing number of vessels are passing through the Arctic Ocean consequently bringing concerns of ship-iceberg collisions. Thus, most classification societies have implemented regulations to determine requirements for ice strengthening in ship structures. This paper presents the simulation results of an ice-strengthened polar class ship after an iceberg collision. The ice-strengthened polar class ship was created in accordance with the Unified Requirements for a Polar-Ship (IACS URI). An elastic-perfect plastic ice model was adopted for this simulation with a spherical shape. A Tsai-Wu yield surface was also used for the ice model. Collision simulations were conducted under the commercial code LS-DYNA 971. Hull deformations on the ice-strengthened foreship structure and collision interaction forces have been analysed in this paper. A normal-strength ship structure in an iceberg collision was also simulated to present comparison results. Distinct differences in structural strength against ice impact forces were shown between the ice-strengthened and normal-strength ship structures in the simulation results. About 1.8 m depth of hull deformation was found on the normal ship, whereas 1.0 m depth of hull deformation was left on the ice-strengthened polar class ship.