• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.254-255
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• 2011

This paper presents a method to analysis the effect for integrating Sihwa tidal power into power systems. Especially, power flow, fault current, voltage and contingency of sihwa tidal power plant area are calculated and the generation characteristics of tidal machine are analyzed.

• 한국항해항만학회지
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• 제31권9호
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• pp.793-799
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• 2007

The effect of seasonal wind on the tidal circulation in Jeju harbor was examined by using a numerical shallow water model. A finite element for analyzing shallow water flow is presented. The Galerkin method is employed for spatial discretization. Two step explicit finite element scheme is used to discretize the time function, which has advantage in problems treating large numbers of elements and unsteady state. The numerical simulation is compared with three cases; Case 1 does not consider the effect of wind, Case 2 and Case 3 consider the effect of summer and winter seasonal wind, respectively. According to result considering effect of seasonal wind, velocity of current vector shows slightly stronger than that of case 1 in the flow field. It can be concluded that the present method is a useful and effective tool in tidal current analysis.

• Ocean and Polar Research
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• 제28권4호
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• pp.361-368
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• 2006

The Saemangeum tidal flat with an area of approxirnately $233km^2$ is one of the biggest estuarine tidal flats on the west coast of Korea. Because of its location in the estuary of Mangyeong and Dongjin Rivers, the tidal flat receives large amount of sediments. A 33-km long sea dyke, enclosing a coastal zone of $401km^2$, was constructed to reclaim tidal flat in the Saemangeum area. The dyke construction radically changes the local tidal current regime and estuarine circulation. These have an effect on sedimentary environments in the tidal flat. On the tidal flats of the study area net deposition occurred, but net erosion occurred near tidal channel in 2004. The comparison of topography and surface sediments in summer 2004 with those in summer 1988 before the dyke construction showed that elevation increased with maximum 80cm and mean grain sizes were fining at Gwanghwal tidal flats. Sedimentary facies of two cores from Gwanghwal tidal flat revealed homogeneous layers in the upper part suggesting rapid deposition after the dyke construction. The sedimentation rate in Gwanghwal tidal flat(GW 6) using $^{210}Pb$ analysis was about 5.4cm/yr which is well matched with the sedimentation pattern revealed by change in topography.

• 물과 미래
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• 제25권2호
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• pp.67-78
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• 1992

Several field surveys were conducted to investigate changes of water quality with time in a tidal river. Results indicated that nitrification process were dependent on the change of salinity and suspended solids concenttration. Therefore laboratory batch experiments were conducted, using suspended solids and sediment taken from a tidal river, to study the effect of salinity on nitrification and to estimate kinetic parameters of it in the tidal river. suspended solids and sediment were sampled at a point in the middle stream. Sediments were collect from the aerobic layer of mud. The change of nitrogen concentration with time was clearly explained with Monod groth model and kinetic parameters were obtained by curve fitting method. Changes in NH4-N, NO2-N, and NO3-N concentrations in the river ROKKAU with time were simulated well using Lagrangian reference frame and parameter values obtained in the laboratory tests. T도 mechanism of nitrification by suspended solids and sediment in a tidal river is shown to depend on tidal effects.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.199-202
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• 2008

It is well-known fact that tidal difference between the ebb and flow in Yellow Sea is about 9 m so that it has largest value in the world. This wide range of tide level enables Yellow Sea water to intrude into main stream of Han River. However, the study of the tidal reach of Han River has not been carried out thoroughly since North and South Koreas share this region so that topography data and physical measurement are lacking. In this study, to examine the reverse flow and dispersion behavior by tidal effect at the tidal reach of Han River, 2-D river analysis models were applied. RMA-2 was applied to calculate the horizontal velocities and water surface elevation. With the results of velocities and water depth, RAM4, which is 2-D advection-dispersion model based on FEM was simulated to analyze the horizontal transport behavior of BOD.

• 한국물환경학회지
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• 제37권6호
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• pp.425-432
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• 2021

A tidal power plant (TPP) has been in operation since the end of 2011 to improve the water quality of Shihwa Coastal Reservoir (SCR). Tidal mixing rate increased 5.6 times after the TPP operation so that in this study, its effects on water quality was assessed through statistical analysis of long-term water quality monitoring data. It was found that the increased tidal mixing contributed to solving the hypoxia problem in the bottom water by preventing the summer stratification. The analysis also showed that the increased tidal mixing had different effects depending on the relative concentration difference for each water quality substances between the SCR and the outside of SCR. The average concentrations of some substances (chemical oxygen demand, total phosphorus, chlorophyll-a) with higher concentrations than the outside of SCR decreased due to the dilution effect, but the other substances (total nitrogen, dissolved inorganic nitrogen, dissolved inorganic phosphorus) with lower concentrations compared to the outside ones increased on the contrary. Factor analysis also showed a consistent result that the first factor accounting for the water quality was changed from the organic-related substances to the nutrient-related substances after the increased tidal mixing. These results imply that the focus of future water quality management needs shifting from the organic substances to the nutrients, particularly dissolved inorganic nutrients. Considering the effect of inflow seawater on the nutrients, the management area should be extended to cover not only SCR but also a certain area outside of SCR.

• International Journal of Ocean System Engineering
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• 제1권3호
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• pp.144-147
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• 2011

The rotor that initially converts the flow energy into rotational energy is a very important component that affects the efficiency of the entire tidal current power system. Rotor performance is determined by various design variables. Power generation is strongly dependent on the incoming flow velocity and the size of the rotor. To extract a large quantity of power, a tidal current farm is necessary with a multi-arrangement of devices in the ocean. However, the interactions between devices also contribute significantly to the total power capacity. Therefore, rotor performance, considering the interaction problems, needs to be investigated to maximize the power generation in a limited available area. The downstream rotor efficiency is affected by the wake produced from the upstream rotor. This paper introduces the performance of a downstream rotor affected by wakes from an upstream rotor, demonstrating the interference affecting various gabs between devices.

• Journal of the korean society of oceanography
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• 제36권3호
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• pp.72-82
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• 2001

The progress of giant dyke construction off the Mangyung and Donajin rivers, has yielded enormous impact on the estuarine environment, both hydrodynamically and sedimentologically. Especially the inter-dyke gap in the northern Saemankeum area, 4 km wide between Yamido and Piungdo, has acted as an artificial tidal inlet. Due to such a changed geometry, tidal regime has been reversed from being flood- to ebb-dominated with a directional change from NE-SW to E-W. As a result, a large tongue-like tidal sand bar (named Saemankeum Bar) has conspicuously grown seaward through the artificial tidal inlet. The Saemankeum Bar composed of well-sorted very fine sands (3.0-3.5${\phi}$) has grown at a rate of 1.63 km/yr for the past three yews (1996-1998). Such a rapid growth of the sand bar is attributed to enhanced sediment supply derived from the degradation of former tidal sand bars at the mouth of the Mangyung River. Eventually the reworking of the tidal sand bars also caused the pre-existing tidal channels to be wider, deeper and more straightened. All of these phenomena well examplify the critical effect of artificial modifications on the natural estuarine environments.

• Ocean and Polar Research
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• 제30권4호
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• pp.485-495
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• 2008

Tidal ranges of inner Saemangeum were largely reduced after the final dyke enclosure, resulting in the former tidal flats becoming either permanently exposed, still influenced by changing tide, or permanently submerged. The effect of reduced tidal range on survival and population stability of tidal flat macrofauna were investigated at three shifted habitats after the dyke completion. At the exposed area, several species survived for 80 days after the dyke enclosure. However, within 120 days, all macrofauna died off due to the elevated temperature during summer. At the intertidal area, some species were maintained until 170 days after the dyke enclosure with a large decrease of the faunal abundance. Species of the submerged area were seen to be more tolerant of the changed environments. The opportunistic species, such as Sinocorophium sinensis, Theora fragilis and Pseudopolydora Kempi, were massively introduced into the submerged area after the dyke enclosure, in which the benthic ecosystem was severely disturbed.

• 한국해양공학회지
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• 제23권1호
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• pp.109-113
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• 2009

Several tidal current power plants are being planned and constructed in Korea utilizing the strong tidal currents along the west and south coasts. A tidal current reaches 9.7 m on the west coast; there are few potential regions for tidal current power generation. The construction of a dam to store water can prevent the circulation of water, causing a great environmental impact on the coast and estuary. The tidal barrage could produce a large amount of power, but it should be carefully considered. The purpose of developing renewable energies is to minimize the environmental impact and to maximize the utilization of clean energy. To produce a great quantity of power, tidal current farms require the placement of numerous units in the ocean. The power generation is very dependent on the size of the rotor and the incoming flow velocity. Also, the interactions between devices contribute greatly to the production of power. The efficiency of a power farm is estimated to determine the production rate. This paper introduces 3 D interaction problems between rotating rotors, considering the axial, transverse, and diagonal distances between horizontal axis tidal current devices.