• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.433-438
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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 vesse. 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 open sea, 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 characteristics 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 Wetlands Research
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• v.8 no.3
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• pp.29-38
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• 2006

Digital Elevation Model (DEM) of intertidal flat can be widely used not only for scientific fields, coastal management, fisheries, ocean safety, military, but also for understanding natural and artificial topographic changes of the tidal flat. In this study, we generated DEM of the Ganghwado southern intertidal flat, the largest tidal flat in the west coast of the Korean Peninsula, using waterline method and interferometric synthetic aperture radar (InSAR). Constructed DEM which applied waterline method to the Landsat-5 TM and Landsat-7 ETM+ images closely expresses overall topographic relief of tidal flat. We found that the accuracy was determined by the number of waterlines which reflect various tidal conditions. The application of InSAR to the ERS-1/2 and ENVISAT images showed that only ERS-1/2 tandem pairs successfully generated DEM in the part of northern Yeongjongdo, but construction of DEM in the other areas was difficult due to the low coherence caused by a lot of surface remnant waters. In the near future, Kompsat-2 will provide satellite images having multi-spectral and high spatial resolution within a relatively short period at different sea levels. Application of waterline method to these images will help us construct a high precision tidal flat DEM. Also, we should develop DEM generation method using single-pass microwave satellite images.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.245-257
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• 2016

Although rivers cover only 0.5% of the total land area on the Earth, they are windows that show the integrated effects of watershed biogeochemistry. Studies on the loads and properties of riverine carbon have been conducted because they are directly linked with drinking water quality, and because regional or global net ecosystem production (NEP) can be overestimated, unless riverine carbon loads are subtracted. Globally, ${\sim}0.8-1.5Pg\;yr^{-1}$ and ${\sim}0.62-2.1Pg\;yr^{-1}$ of carbon are transported from terrestrial ecosystems to the ocean via rivers and from inland waters to the atmosphere, respectively. Concentrations, ${\delta}^{13}C$, and fluorescence spectra of riverine carbon have been investigated in South Korea to understand the spatiotemporal changes in the sources. Precipitation as well as land use/land cover can strongly influence the composition of riverine carbon, thus shifting the ratios among DIC, DOC, and POC, which could affect the concentrations, loads, and the degradability of adsorbed organic and inorganic toxic materials. A variety of analyses including $^{14}C$ and high resolution mass spectroscopy need to be employed to precisely define the sources and to quantify the degradability of riverine carbon. Long-term data on concentrations of major ions including alkalinity and daily discharge have been used to show direct evidence of ecosystem changes in the US. The current database managed by the Korean government could be improved further by integrating the data collected by individual researchers, and by adding the major components ions including DIC, DOC, and POC into the database.

• Journal of Marine Life Science
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• v.4 no.1
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• pp.14-21
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• 2019

This review paper discussed the decadal fluctuations in the catch of the common squid, Todarodes pacificus (T. pacificus) by focusing on migration and distribution patterns. Since 1980s, changes in T. pacificus catches were due to climate regime shift in Korean waters. Fluctuation patterns of catches were different between the East Sea and the Yellow Sea. Generally PDO (Pacific Decadal Oscillation) phase shows a negative correlation with strength of warm current to the East Sea. In 1980s when PDO was positive phase (+), T. pacificus catch was higher in the Yellow, but it was lower in the East Sea. In 1990s when PDO was negative phase (-), T. pacificus catch showed opposite trend compared with 1980s. Such spatial and decadal fluctuations of T. pacificus catch were due to its northward migration along with the warm current or southward movement against the current. In the East Sea, strong (weak) warm current period, the current path has been shifted toward the East Sea coast of Korea (central East Sea or the coast of Japan). It has a correlation with PDO. In the positive PDO phase (1980s), the fishing ground was located on the eastern side of Ulleungdo, whereas during negative PDO phase (1990s), they were situated near the southeastern coast of the Korean peninsula. In the 1980s, volume transport passing into the Yellow Sea increased, whereas volume transport in the East Sea decreased. This is one of major reason increasing T. pacificus larvae in the Yellow Sea.

• ALGAE
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• v.34 no.2
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• pp.111-126
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• 2019

The phototrophic dinoflagellate Biecheleriopsis adriatica is a small suessioid species characterized by a fragile thin wall. Although the morphology of this dinoflagellate is well established, there is currently little information available on its distribution and the environmental factors that influence this distribution. Thus, to investigate the spatial and seasonal distributions of the vegetative cells of B. adriatica in Korean waters, surface water samples were collected on a seasonal basis from 28 stations in the East, West, and South Sea of Korea and Jeju Island from April 2015 to October 2018, and abundances of the vegetative cells of B. adriatica were quantified using quantitative real-time polymerase chain reactions, for which we developed the species-specific primer and probe set. Simultaneously, major environmental parameters, including temperature, salinity, nutrient concentrations, and dissolved oxygen concentrations were measured. The vegetative cells of B. adriatica were detected at 20 of the 28 sampling stations: 19 stations in summer and 6 in autumn, although from no stations in either spring or winter. The ranges of water temperature and salinity at sites where this species was detected were $17.7-26.4^{\circ}C$ and 9.9-34.3, respectively, whereas those of nitrate and phosphate concentrations were not detectable-96.2 and $0.18-2.66{\mu}M$, respectively. Thus, the sites at which this species is found are characterized by a narrow range of temperature, but wide ranges of salinity and concentrations of nitrate and phosphate. The highest abundance of the vegetative cells of B. adriatica was $41.7cells\;mL^{-1}$, which was recorded in Jinhae Bay in July 2018. In Jinhae Bay, the abundance of vegetative cells was significantly positively correlated with the concentration of nitrate, but was negatively correlated with salinity. On the basis of these findings, it appears that the abundance of B. adriatica vegetative cells shows strong seasonality, and in Jinhae Bay, could be affected by the concentrations of nitrate.

• Journal of Navigation and Port Research
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• v.46 no.3
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• pp.209-215
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• 2022

On the Jeju coast, international cruise ships, passenger ships, and other ships pass frequently, as well as many fishing boats. Thus, there is a high risk of marine accidents and frequent ship collisions. Accordingly, it is urgent to establish a coastal VTS for systematic safety management of ships passing through the coastal waters of Jeju. The purpose of this study was to set the area of the VTS to be newly established. In this study, to calculate the workload of the VTS operators, a formula was proposed that reflects the monitoring workload considering the monitoring frequency and required time for target as well as non-target ships and the workload for ship collision situations. The proposed formula was applied to the newly established VTS area in Jeju. Three control sectors were set up in each VTS center. The average number of workstations per hour was approximately 1, so the division between sectors was appropriate. Thus, it was deduced that there would be no workload for the VTS operators. It is expected that the method proposed in this study can be used as primary data for calculating the appropriate number of workstations for the current VTS, and setting the VTS area for a new coastal VTS in the future.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.297-303
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• 2021

When sound waves propagate over long distances in shallow water, measured transmission loss is greater than predicted one using underwater acoustic model with the Rayleigh reflection model due to inhomogeneity of the bottom. Accordingly, the US Navy predicts sound wave propagation by applying the empirical formula-based High Frequency Bottom Loss (HFBL) model. In this study, the measurement and analysis of transmission loss was conducted using mid-frequency (2.3 kHz, 3 kHz) in the shallow water of the East Sea in summer. BELLHOP eigenray tracing output shows that only sound waves with lower grazing angle than the critical angle propagate long distances for several kilometers or more, and the difference between the predicted transmission loss based on the Rayleigh reflection model and the measured transmission loss tend to increase along the propagation range. By comparing the Rayleigh reflection model and the HFBL model at the high grazing angle region, the bottom province, the input value of the HFBL model, is estimated and BELLHOP transmission loss with HFBL model is compared to measured transmission loss. As a result, it agrees well with the measurements of transmission loss.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.254-261
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• 2022

Every vessel shall proceed at a safe speed to avoid collision. Additionally, every vessel shall comply with the speed limit rules in the territorial water and internal waters of Korea. The VTS operator shall properly control the compliance of the vessel with the safe speed and speed limit rules. Safe speed under the COLREG 1972 is not explicitly stipulated in knots. However, under the Domestic law for traffic safety-specific sea areas, etc., the speed limit is specified in knots and complied with. This speed limit rule is mainly based on the 'speed made good over the ground'; however, in some places, it is based on the 'speed making way through the water'. In this paper, I analyzed marine accidents that occurred in the past 5 years and the rate of violation of speed limits. Furthermore, I reviewed safe speed under the COLREG 1972, speed limit rules under domestic and foreign laws, and cases of non-compliance with safe speed in the judgment of the Korea Maritime Safety Tribunal. Resultantly, I suggested in this paper that the speed limit rules in the domestic law must be observed by vessels to prevent marine accidents, and the rules which are stipulated in terms of 'speed making way through the water' must be revised as 'speed made good over the ground' such that the vessels can easily comply with them and the VTS operator can control the vessel properly.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.865-875
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• 2022

Field measurements and numerical simulations using EFDC model were performed to quantify the changes of water circulation near Gusipo coast located in the Yellow Sea of Korea to estimate the impact of the construction of the coastal structures (jetty, groin, Gusipo port and bridge). The model predicted tide and tidal currents agreed reasonably well with the measurements. The maximum currents during spring tide near the Gusipo Beach (GB) have the range of 20~40 cm/sec whereas those off the GB range from 60 to 80 cm/sec. The typical patterns of tidal current show parallel with the local isobath. Tidal currents flow northeastward during the flood tide whereas the currents during the ebb tide flow southwestward. The current speeds at shielded waters after the construction of coastal structures strongly decreased as compared with those before the construction. The tidal volume due to the construction of coastal structures was estimated using the depth averaged velocity for 24 hours of spring tide. Tidal volume after construction of coastal structures was compared with initial state (before construction). Tidal volume at present state (after construction of jetty, groin, Gusipo port and bridge) decreased by 28.4% as compared with that of the initial state. The volume after construction of jetty and groin decreased by 21.3%, and the volume after construction of Gusipo port and bridge decreased by 9.8%.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.515-524
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• 2022

To effectively collect, manage, and share the maritime traffic information, it is necessary to identify the technology trends concerning this particular information and analyze its current status and problems. Therefore, this study observes the domestic and foreign technology trends involving maritime traffic information while analyzing and summarizing the current status and problems in collecting, managing, and sharing it. According to the data analysis, the problems in the collecting stage are difficulties in collecting visual information from long-distance radars, CCTVs, and cameras in areas outside the LTE network coverage. Notably, this explains the challenges in detecting smuggling ships entering the territorial waters through the exclusive economic zone (EEZ) in the early stage. The problems in the management stage include difficult reductions and expansions of maritime traffic information caused by the lack of flexibility in storage spaces mostly constructed by the maritime transportation system. Additionally, it is challenging to deal with system failure with system redundancy and backup as a countermeasure. Furthermore, the problems in the sharing stage show that it is difficult to share information with external operating organizations since the internal network is mainly used to share maritime transportation information. If at all through the government cloud via platforms such as LRIT and SASS, it often fails to effectively provide various S/W applications that help use maritime big data. Therefore, it is suggested that collecting equipment such as unmanned aerial vehicles and satellites should be constructed to expand collecting areas in the collecting stage. In the management and sharing stages, the introduction and construction of private clouds are suggested, considering the operational administration and information disclosure of each maritime transportation system. Through these efforts, an enhancement of the expertise and security of clouds is expected.