• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.192-199
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• 2024

Wave overtopping is a significant natural hazard that occurs in coastal areas, primarily driven by high waves, particularly those generated during typhoons, which can cause coastal flooding. The development of residential and commercial areas along the coast, driven by increasing social and economic demands, has led to a concentration of people and assets in these vulnerable areas. This, coupled with long-term sea level rise and an increase in typhoon frequency, has heightened the risk of coastal hazards. Traditionally, the evaluation of wave overtopping volumes has relied on directly measuring the collected volume of water that exceeds the crest height of structures through hydraulic model experiments. These experiments are averaged over a specific measurement period. However, in this study, we propose a new method for estimating individual wave overtopping volumes. We utilize the temporal variation of wave overtopping heights to develop an observation system that can quantitatively assess wave overtopping volumes in actual coastal areas. To test our method, we conducted hydraulic model experiments on rubble mound breakwaters, which are commonly installed along the Korean coast. We introduce wave overtopping discharge coefficients, assuming that the inundation velocity from the structure's crest is the long-wave velocity. We then predict overtopping volumes based on wave overtopping heights and compare and review the results with experimental data. The findings of our study confirm the feasibility of estimating wave overtopping volumes by applying the overtopping discharge coefficients derived in this study to wave overtopping heights.

• Proceedings of the Korean DIstribution Association Conference
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• 2006.08a
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• pp.47-68
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• 2006

This study aims to determine the association structure of the behavioral relationship variables, such as trust, commitment, cooperation, communication and coercive power, in the relationship between the buyers and suppliers of industrial parts. It also investigates the impact of the use of IT technologies on the relationships quality. Data was collected from 216 part suppliers of machinery, electronics and automobiles located in Incheon. Data supported all of the proposed hypotheses. First, it was confirmed that parts suppliers' trust in buyers leads to the commitment into relationships with buyers. Second, cooperation and communication showed a positive influence on parts suppliers' trust in buyers, and coercive power gave a negative influence on trust. Third, the use of IT technologies like Internet and E-Mail between parts suppliers and buyers was verified to have generally a positive influence on the quality of relationships. At the same time, cooperation and communication were confirmed to have a positive influence on each other, and cooperation and coercive power as well as communication and coercive power were confirmed to have negative influence on each other. This study is a pioneering attempt to examine the relationships between suppliers and buyers of industrial parts, and the influence IT technologies on the relationship quality. Also, the findings will be practically much helpful to find how to reinforce the relationships between parts suppliers and buyers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.655-661
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• 2015

This study intends to evaluate the effect of nitric acid($HNO_3$) spill accidents on the marine ecosystem, while $HNO_3$ is known as one of the typical HNS. For this purpose, we performed (1) the growth inhibition test by using phytoplankton(Skeletonema costatum), (2) acute and chronic toxicity test by using invertebrate(Brachionus plicatilis and Monocorphium acherusicum), (3) fish(Cyprinodon variegatus) and (4) bacteria(Vibrio fischeri). In these tests, we observed the (1) pH changes induced by the nitric acid spill and (2) changes in nitrate($NO_3$) concentration disassociated from nitric acid after the accident, respectively. The toxicity test result on pH changes induced by $HNO_3$ shows that the no observed effect concentration(NOEC), lowest observed effect concentration(LOEC) and 50 % effect concentration($72h-EC_{50}$) values of M. acherusicum are pH 7 (0.3 mM), pH 5(1.1 mM) and pH 5.2(1.4 mM), respectively, indicating that M. acherusicum is the most sensitive species. The chronic toxicity test (population growth rate test) on $NO_3{^-}$ of B. plicatilis show that the NOEC, LOEC and $96h-EC_{50}$ are 5.9 mM, 11.8 mM and 32.6 mM, respectively, indicating that B. plicatilis is the most sensitive species. In conclusion, toxic effecst on the marine organism caused by the nitric acid spill accident is determined to be so slightly except for the most adjacent area of the ship in pH scale and such concentration of nitrate, to the extent of directly influencing the survival and reproduction of the marine organism, is determined practically not to be applicable in the typical accidents in the sea.