• Journal of Korea Water Resources Association
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• v.45 no.9
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• pp.959-968
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• 2012

HEC-RAS has been applied to simulate water level variation in the Ara waterway during the flood season. To support decision making necessary for operation of the hydraulic structures especially during the flood season, it is important to consider various factors such as water level of the Han River, Gulpo River, and tidal level of the west sea in conjunction with operation of the hydraulic structures such as the Gyulhyun Weir, the West sea gate, and pumping stations. Especially for operation of the west sea gate, the Rule-script option was employed to determine the opening height considering the variation of the water level in the waterway and the west sea simultaneously. For model verification, comparison of water level computed at the upstream and downstream of the regulation weir shows a good agreement with observed data measured during the flood event in September 2010. The HEC-RAS model developed in this study will contribute to support operation of the waterway during the flood season.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.8
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• pp.709-717
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• 2013

This paper presents the development of a specialized underwater leg with a manipulator function(convertible-to-arm leg) for the seabed walking robot named CRABSTER200(CR200). The objective functions of the convertible-to-arm leg are to walk on the seabed and to work in underwater for precise seabed exploration and underwater tasks under coastal area with strong tidal current. In order to develop the leg, important design elements including the degree of freedom, dimensions, mass, motion range, joint structure/torque/angular-speed, pressure-resistance, watertight capability and cable protection are considered. The key elements of the convertible-to-arm leg are realized through concept/specific/mechanical design and implementation process with a suitable joint actuator/gear/controller selection procedure. In order to verify the performance of the manufactured convertible-to-arm leg, a 25bar pressure-resistant and watertight test using a high-pressure chamber and a joints operating test with posture control of the CR200 are performed. This paper describes the whole design, realization and verification process for implementation of the underwater convertible-to-arm leg.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.2
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• pp.140-148
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• 2007

This paper describes on the real-time monitoring of dredging information for grab bucket dredger equipped with winch control sensors and differential global positioning system(DGPS) using electronic chart display and information system(ECDIS). The experiment was carried out at Gwangyang Hang and Gangwon-do Oho-ri on board M/V Kunwoong G-16. ECDIS system monitors consecutively the dredging's position, heading and shooting point of grab bucket in real-time through 3 DGPS attached to the top bridge of the dredger and crane frame. Dredging depth was measured by 2 up/down counter fitted with crane winch of the dredger. The depth and area of dredging in each shooting point of grab bucket are displayed in color band. The efficiency of its operation can be ensured by adjusting the tidal data in real-time and displaying the depth of dredging on the ECDIS monitor. The reliance for verification of dredging operation as well as supervision of dredging process was greatly enhanced by providing three-dimensional map with variation of dredging depth in real time. The results will contribute to establishing the system which can monitor and record the whole dredging operations in real-time as well as verify the result of dredging quantitatively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3583-3589
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• 2010

The semi-implicit scheme proposed by Backhaus is introduced to solve two-dimensional shallow water equation. This mothod is applied for the numerical model solving surface elevation and velocity field of Geum River estuary. For the verification of the method, numerical solutions by this model are compared with ones by Heap's well known explicit model. Solutions of two models resemble each other. The time-step chosen for the semi-implicit scheme turned out to be 3 to 6 times longer than explicit model depending on the stringent CFL criterion. The computation time could be reduced at least 50%. It was proved that this scheme is easy to handle dry banks which can be seen in Geum River estuary and numerical stability is obtained for long time computation.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.3
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• pp.20-28
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• 2000

The objective of this study is to establish a methodology of bioregional approach for coastal area management as a basis for planning and design. Focusing on the bioregional approach, this study reviewed currently prevailing approaches such as watershed approach and ecological unit approach for planning and management purposes. This research placed its geographical focus on the landward watershed of the Bay of Hampyong located in Chonnam Province, dealing efficiently with shortcomings of existing researches which mainly covered seaward tidal flats without considering outside effects. The main methods of the study are classified into indoor computerized map analysis and field work. For computer analysis, printed maps and digital maps have been analysed, and GIS techniques have been utilized for its synthesis and finalizations. Field work included on-site landscape analysis and verification of a tentative place unit boundary. As a practical step, criteria for classifying bioregion were presented and the selected criteria included : topography & water ways ; roads & administrative boundaries ; habitat types ; and visual enclosure. First, based on the data of topography and water ways, broad classification work was performed and corrections were made based on data drawn out from other criteria. A tentative place unit map was drawn and revised through field visits. This study encompassed an initial but integral part for bioregional approach in landward watershed management of a coastal area. As results of the study, the necessity and efficiency of bioregional approach which considers environmental and cultural components systematically have been presented.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.485-500
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• 2002

Hydraulic model was developed to analyze the complex flow due to channel structures, tide, and tributaries in the lower Han river and Imjin river. DWOPER-2K model which can automatically process the data transformation in the model was developed as the 1-D hydraulic routing model. Observed data in tidal zone and the recent channel geometry data were collected for hydraulic model. And the flow over the Jamsil and Singok submerged weir was analyzed properly and roughness coefficient was optimized to each regions and each discharges. By the results of verification of the model, the model developed in this study may contribute to improvement of the accuracy of flood forecasting and channel management because this model can efficiently and properly analyze the various kind of flow occurred in the region of the lower Han river and Imjin river.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3B
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• pp.335-343
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• 2008

A hydrodynamic numerical model, ESCORT, which enables wetting-and-drying simulation, is developed. The model is verified by applying it at the Mokpo coastal zone together with the MIKE21 model. This paper deals in only 2-dimensional aspects remaining 3-dimensional function for further research. To begin with, MIKE21 model is applied at the whole area where MIKE21 had been applied several times to produce boundary conditions for the main area. Unlike the whole area of uniform grid, main area adopts telescoping grid for ESCORT model and nested grid for MIKE21 model. The results of both model show not only good agreement for the values of water depth and tidal velocity between computed and observed ones, but also plausible wetting-and-drying simulation. However, ESCORT model needs some improvement of efficiency.

• Journal of Life Science
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• v.32 no.7
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• pp.578-587
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• 2022

Korea, as the world's 7^th largest emitter of greenhouse gases, has raised the national greenhouse gas reduction target as international regulations have been strengthened. As it is possible to utilize coastal and marine ecosystems as important nature-based solutions (NbS) for implementing climate change mitigation or adaptation plans, the blue carbon ecosystem is now receiving attention. Blue carbon refers to carbon that is deposited and stored for a long period after carbon dioxide (CO₂) is absorbed as biomass by coastal ecosystems or oceanic ecosystems through photosynthesis. Currently, there are only three blue carbon ecosystems officially recognized by the Intergovernmental Panel on Climate Change (IPCC): mangroves, salt marshes, and seagrasses. However, the results of new research on the high CO₂ sequestration and storage capacity of various new blue carbon sinks, such as seaweeds, microalgae, coral reefs, and non-vegetated tidal flats, have been continuously reported to the academic community recently. The possibility of IPCC international accreditation is gradually increasing through scientific verification related to calculations. In this review, the current status and potential value of seaweeds, seagrass fields, and non-vegetated tidal flats, which are sources of blue carbon on the east coast, are discussed. This paper confirms that seaweed resources are the most effective NbS in the East Sea of Korea. In addition, we would like to suggest the direction of research and development (R&D) and utilization so that new blue carbon sinks can obtain international IPCC certification in the near future.

• Development and Reproduction
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• v.21 no.1
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• pp.55-62
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• 2017

We used flowcytometry to ploidy verification after that investigate difference between diploid and spontaneous triploid through the truss dimension and classical dimension at crucian carp, Carassius auratus, crucian carp C. cuvieri and common carp, Cyprinus carpio collected from Hangang river, Hantangang river, Imjingang river, Geumgang river, Yeongsangang river and Nakdonggang river, Korea. There were significant differences among the three species for the truss dimensions anterior origin of dorsal fin $(2){\times}$ anterior origin of anal fin (5), $2{\times}$ anterior origin of pelvic fin (6), $2{\times}$ origin of pectoral fin (7), posterior origin of dorsal fin $(3){\times}5$, $3{\times}6$, and $3{\times}7$ (P<0.05). There were no significant differences among the three species in the truss dimensions dorsal fin length ($2{\times}9$) and eye diameter (ED)(P>0.05). On the other hand, there were no significant differences in the several classical dimensions of each species (P>0.05). Three classical dimensions, most anterior extension of the head $(1){\times}2$, $1{\times}6$ and $2{\times}$ most posterior scale in lateral line (4) did not differ between the C. auratus diploid and spontaneous triploid (P>0.05). Two classical dimensions, $1{\times}6$ and longest length between most anterior extension of the head and gill cover ($1{\times}8$) did not differ between the C. cuvieri diploid and spontaneous triploid (P>0.05). One classical dimensions, $1{\times}2$ did not differ between the common carp diploid and spontaneous triploid (P>0.05). There were significant differences in the each diploid and triploid species (P<0.05). These results suggest that the classification of each species and classification between diploid and spontaneous triploid morphometrical parameters used in this study are useful indices of morphometrical status in the each species from major river of Korea.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.249-261
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• 2020

Coastal monitoring using multiple platforms/sensors is a very important tools for accurately understanding the changes in offshore marine environment and disaster with high temporal and spatial resolutions. However, integrated observation studies using multiple platforms and sensors are insufficient, and none of them have been evaluated for efficiency and limitation of convergence. In this study, we aimed to suggest an integrated observation method with multi-remote sensing platform and sensors, and to diagnose the utility and limitation. Integrated in situ surveys were conducted using Rhodamine WT fluorescent dye to simulate various marine disasters. In September 2019, the distribution and movement of RWT dye patches were detected using satellite (Kompsat-2/3/3A, Landsat-8 OLI, Sentinel-3 OLCI and GOCI), unmanned aircraft (Mavic 2 pro and Inspire 2), and manned aircraft platforms after injecting fluorescent dye into the waters of the South Sea-Yeosu Sea. The initial patch size of the RWT dye was 2,600 ㎡ and spread to 62,000 ㎡ about 138 minutes later. The RWT patches gradually moved southwestward from the point where they were first released,similar to the pattern of tidal current flowing southwest as the tides gradually decreased. Unmanned Aerial Vehicles (UAVs) image showed highest resolution in terms of spatial and time resolution, but the coverage area was the narrowest. In the case of satellite images, the coverage area was wide, but there were some limitations compared to other platforms in terms of operability due to the long cycle of revisiting. For Sentinel-3 OLCI and GOCI, the spectral resolution and signal-to-noise ratio (SNR) were the highest, but small fluorescent dye detection was limited in terms of spatial resolution. In the case of hyperspectral sensor mounted on manned aircraft, the spectral resolution was the highest, but this was also somewhat limited in terms of operability. From this simulation approach, multi-platform integrated observation was able to confirm that time,space and spectral resolution could be significantly improved. In the future, if this study results are linked to coastal numerical models, it will be possible to predict the transport and diffusion of contaminants, and it is expected that it can contribute to improving model accuracy by using them as input and verification data of the numerical models.