• Journal of Navigation and Port Research
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• v.30 no.9
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• pp.755-762
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• 2006

When we consider to develop a new harbor, the most important factor, we think, is the lowest water depth of waterway and approaching channel for safe navigation of vessel. The existing harbors have been being dredged to meet the international trend of jumbo sized vessels by adopting the new design criteria. As the dredged materials over the expected at the design level were common and there are still lack of land based reclamation area, we have no choice to discharge the dredged materials in open sea area In this study, we analysed the behavior of discharged materials at the dumping area of offshore, which were collected from the dredging work at the waterway in Busan New Port. We measured the tidal currents and analyzed the waters of dumping site after the dumping work. These were used to evaluate the numerical models. Suspended Solids(SS) were introduced to the diffusion model. Because of the characteristic of the dumping site, the speed of initial diffusion and settle down of the discharged materials was so fast. Therefore, we believe that the dumped materials do not cause a significant impact to the marine environment.

• Journal of Navigation and Port Research
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• v.30 no.9
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• pp.735-740
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• 2006

Marine officers should have crisis control ability because ship operation needs not only highly specialized information, but also functional capability due to the fact that there always exist dangers at sea, which are different from those at shore. Therefore, marine officers should be trained on the related specialized information under the systematical educational system including shipboard training. Their training is also based on the strong spiritual power and physical strength through the strict training process. In order to have these vocational personalities, dormitory life training and shipboard training courses seem to be essential processes, which are required of maritime education. The introduction of automatic system into the ship as a result of the recent development of technology brings decrease of the full number of crew. Consequently, marine officers are increasingly under heavy burden, and should have more ship operation capabilities than before. Maine officers should have not only specialized information which differs from that at shore, but also vocational adaptability which can reasonably tackle with all the problems which exist on the spot and are obstacles to individual, spiritual, physical, natural, and social demands. So it is required that marine officers should have study many areas to deal with as extra curricula besides their major field of study, which are unique characteristics of the education for them. These vocational adaptabilities are based on the spiritual characteristics, such as self-developmental education, responsibility, meticulous care, attentiveness, voluntary, planning, readiness, spontaneity, accuracy, self-denial, obedience, leadership, and etc.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.145-150
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• 2004

Using the DGPS of high precision take in a bouy, the wave-induced currents were observed by Lagrange method at Bonggile beach of the East Sea. At June, the northward wave-induced currents were dominated by the SSW waves. And the southward flaws were appeared at September and November. When 0.2-0.4m wave heights attacked the beach, the mean speed of the wave-induced currents was 0.15-0.3m/s at June and September, when the 1.0-1.6m wave heights incidented at November, that was about 0.3-0.6m/s. On the other hand, the observed results were compared with the simulated results which were solved by the 2-D model, WICU-DIVAST. It was showed the reasonable agreements.

• Asian Journal of Atmospheric Environment
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• v.8 no.3
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• pp.115-125
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• 2014

In this study, particle composition data for $PM_{10}$ samples were collected every 3 days at Seoul, Korea from August 2006 to November 2007, and were analyzed to provide source identification and apportionment. A total of 164 samples were collected and 21 species (15 inorganic species, 4 ionic species, OC, and EC) were analyzed by particle-induced x-ray emission, ion chromatography, and thermal optical transmittance methods. Positive matrix factorization (PMF) was used to develop source profiles and to estimate their mass contributions. The PMF modeling identified nine sources and the average mass was apportioned to secondary nitrate (9.3%), motor vehicle (16.6%), road salt (5.8%), industry (4.9%), airborne soil (17.2 %), aged sea salt (6.2%), field burning (6.0%), secondary sulfate (16.2%), and road dust (17.7%), respectively. The nonparametric regression (NPR) analysis was used to help identify local source in the vicinity of the sampling area. These results suggest the possible strategy to maintain and manage the ambient air quality of Seoul.

• Journal of computational fluids engineering
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• v.20 no.2
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• pp.52-60
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• 2015

The objective of this research lies in the effect of installation parameters influencing on the wind proof performance of the coastal forest for damage prevention. The dissipation ratio of incident wind power is developed as an assessment index to make a lumped parameter study possible. From the real field data of East, West, and South Sea bounded on the Korean peninsula, single and double storied forests were modeled in three-dimensional shape with computer aided design, and so was done the artificial structures such as wind break, sand accumulating fence, and sand dune, etc With a commercial code ANSYS-CFX, the computational result from the comparison of dissipation ratio between single and double storied forest shows the effect of composition, and also the installation effect is investigated for artificial structures with optimal dimension of distance.

• Ocean Systems Engineering
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• v.9 no.4
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• pp.391-407
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• 2019

Tracking the location (position) of a surface or underwater marine vehicle is important as part of guidance and navigation. While the Global Positioning System (GPS) works well in an open sea environment but its use is limited whenever testing scaled-down models of such vehicles in the laboratory environment. This paper presents the design, development and implementation of a low energy ultrasonic augmented single beacon-based localization technique suitable for such requirements. The strategy consists of applying Extended Kalman Filter (EKF) to achieve location tracking from basic dynamic distance measurements of the moving model from a fixed beacon, while on-board motion sensor measures heading angle and velocity. Iterative application of the Extended Kalman Filter yields x and y co-ordinate positions of the moving model. Tests performed on a free-running ship model in a wave basin facility of dimension 30 m by 30 m by 3 m water depth validate the proposed model. The test results show quick convergence with an error of few centimeters in the estimated position of the ship model. The proposed technique has application in the real field scenario by replacing the ultrasonic sensor with industrial grade long range acoustic modem. As compared with the existing systems such as LBL, SBL, USBL and others localization techniques, the proposed technique can save deployment cost and also cut the cost on number of acoustic modems involved.

• Korean Journal of Computational Design and Engineering
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• v.15 no.3
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• pp.189-203
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• 2010

The axiomatic design principles are applied to the conceptual design of semi-submersible type mobile harbor (B1). The process of how the design of mobile harbor is elaborated, evaluated and improved from the very beginning is presented in this paper. The concept of mobile harbor is a functional harbor, which can move to a container ship anchoring out of ports in the deep water to load/unload containers on sea and transfer them to their destination ports. This floating system will innovate the maritime transport and distribution since it will greatly enhance the accessibility of super-sized container ships to existing harbors and harbors without enough infrastructures. Designing a mobile system which can perform the functions of traditional harbors on the floating system requires innovative ideas as well as rigorous validations of each sub systems. In order to enhance the chance of design success, we try to satisfy the design axioms in early stage of conceptual design. We use the zigzagging process for defining Functional Requirements (FR)-Design Parameters (DP) hierarchy due to the complexity of the system. In other words, we decomposed the complexity of the design by FR-DP hierarchy and reduced coupled design logically and systematically. This paper shows applicability of the axiomatic design principles to the field of ocean systems engineering.

• Journal of Contemporary Eastern Asia
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• v.19 no.1
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• pp.84-96
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• 2020

The Republic of Korea (Korea) and the Russian Federation (Russia) are actualizing the cooperation in the Arctic area. As a result, Korean companies have begun to enjoy real economic benefits. However, since there are some troublesome aspects associated with this cooperation, measures that can lead to sustainable development through the supplementation of relevant norms are critical. Russia is also aware of these problems in obtaining economic benefits in the future; cooperation between the two countries should be extended to sufficiently cover this point. The laws related to the region are vague and do not encompass every field. In addition, when it comes to national interests, many situations arise from areas where international and national laws are not clearly harmonized. Therefore, efforts should be made to reflect the interests of both sides and to maintain economic benefits, in case Korea participates in Russia's development of the area, as well as for the legal foundation to reduce negative issues. The Korea-Russia Free Trade Agreement (FTA) negotiation is on the track for the purpose. The two governments should consider various tasks, such as harmonizing with the former FTAs and dealing with the domestic law in accordance with the new FTA. The two countries also have to conduct researches on the efficient use of the FTA and for the 'Sustainable Arctic Development'.

• Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.325-332
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• 2015

An active stimulating method for juvenile fishes to drive escaping from mesh of the codend was examined by shaking canvas in the bottom trawl followed by shrimp beam trawl. Field fishing trials by a bottom trawl were carried out between the Geomoondo and Jejudo in west of South sea, Korea by conver-net methods to examine the effect on the reduction of juvenile fish as a discard catch by generating a shaking movement of the codend using two pieces of asymmetrical semi-circular canvas. The mean period of the shaking motion with the round canvas was 10-15 s, and the range of amplitude as a vertical depth change was up to 0.4-0.6 m when towing speed 3.4-4.3 k't as estimated by peak event analysis. The escape rate of juvenile fish in conver-net by total juvenile bycatch (codend and cover-net) in 14 trials increased from 20% in a steady codend to 34% using a shaking codend in the bottom trawl, while the marketing catch or total bycatch was similar between steady and shaking cod ends. There was no difference in the body size of the fish and species composition between the steady and shaking cod ends. Above results demonstrate a new method for bycatch reduction actually up to 18% using an active stimulating device, although further experiments are needed to increase an effective shaking motion of the codend in amplitude and period for more bycatch reduction.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.33.1-33.1
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• 2009

To date, nanostructured tungsten oxides with a variety of stoichiometries, such as WO3, WO2.9, W18O49, and WO2, have been prepared, because they are promising candidates for applications such as gas sensors, photocatalysts, electrochromic devices, and field emission devices. Among them, W18O49 and WO2 have been widely studied due to their outstanding chemical sensing, catalytic, and electron emissive properties. Here we report, for the first time, a one-pot solution-phase route to synthesizing a novel composite hierarchical hollow structure without adding catalysts, surfactants, or templates. The products, consisting of a WO2 hollow core sphere surrounded by a W18O49 nanorod shell (yielding a sea urchin-like structure), were generated as discrete structures via Ostwald ripening. To our knowledge, this type of composite hierarchical core/shell structure has not been reported previously. The morphological evolution and the detailed growth mechanism were carefully studied. We also demonstrate that the size of the hollow urchins is readily tunable by controlling the reactant concentrations.Interestingly, although bulk tungsten oxides are weakly paramagnetic or diamagnetic, the as-prepared products show unusual ferromagnetic behavior atroom temperature. The urchin structures also show a very high Brunauer-Emmet-Teller (BET) surface area, suggesting that they may potentially be applied to chemical sensor or effective catalyst technologies.