• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.313-326
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• 2021

A submerged body with varied control inputs can execute large drift angles and large angles of attack, as well as basic control such as straight movement and turning. The objective of this study is to analyze the dynamic characteristics of a submerged body comprising six thrusters and six control planes, which is capable of a large drift angle and angle of attack motion. Virtual captive model tests via were analyzed via computational fluid dynamics (CFD) to determine the dynamic characteristics of the submerged body. A test matrix of virtual captive model tests specialized for large-angle motion was established. Based on this test matrix, virtual captive model tests were performed with a drift angle and angle of attack of approximately 30° and 90°, respectively. The characteristics of the hydrodynamic force acting on the horizontal and vertical surfaces of the submerged body were analyzed under the large-angle motion condition, and a model representing this hydrodynamic force was established. In addition, maneuvering simulation was performed to evaluate the standard maneuverability and dynamic characteristics of large-angle motion. Considering the shape characteristics of the submerged body, we attempt to verify the feasibility of the analysis results by analyzing the characteristics of the hydrodynamic force when the large-angle motion occurred.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.5
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• pp.472-481
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• 2008

In this study hydraulic experiment was carried out to investigate the flow characteristics in the submerged outlet structure of Boryeong power plant and the efficiency of bubble reduction by installing horizontal porous plate in the outlet structure. The cross-sectional mean velocity in the submerged outlet structure was smaller than 1 m/s, the target value at the design stage to prevent bubble outflow to the open sea area. In addition, it was found that the maximum depth of bubble penetration is reduced 30 to 50% by installing the horizontal porous plate at the second falling location in the submerged outlet structure. It is expected that the total bubble amount entrained in the water will be most efficiently reduced by installing square-hole-shape porous plate of 20 cm hole size and making its central section as non-porous structure to dissipate the energy of falling water.

• Journal of Environmental Impact Assessment
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• v.15 no.6
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• pp.407-415
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• 2006

This study carried out submerged area due to Dam construction in the near future. It includes species classification of plant, survey of community structure, examination of pollutant load and assessment of water quality impact. The vascular plants of this area are listed 224 taxa; 64 families, 168 genera, 193 species, 30 varieties and 1 form. This study area is classified into total 21 communities, most community was consist of grass vegetation. Among the communities, Erigeron annuus ($869,286m^2$, 22%) community was dominant and Erigeron annuus-Avena fatua comminity (16%) was subdominant until May, and then Erigeron canadensis community occupied most area to $1,774,985m^2$ (32%) from May to July. For the evaluation of water quality impact due to submerged macrophyte, nutrient release test was conducted both dead body macrophyte and living body macrophyte. The results of release test show that T-N is not released at dead body macrophyte, but it is released at living body macrophyte, especially living body Artemisia priceps var. orientalis shows 1.436mgN/g. At release test of dead body macrophyte, T-P release rate of Erigeron annuus shows 0.500mgP/g at the top of them and it also shows 0.436mgP/g at Erigeron annuus of living body macrophyte. T-N load of submerged macrophyte shows 0.76% by comparison of total load on watershed and T-P load of that shows 3.61%. In case of removal macrophyte for reduction of pollutant load in submerged area, T-N load of submerged macrophyte changes from 0.76% to 0.15% by comparison of total load on watershed and T-P load of that changes from 3.61% to 0.72%.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.289-300
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• 2013

In this study, two types of wetland plants, Eichhornia crassipes (a floating plant) and Ceratophyllum demersum (a submerged plant) were introduced to wetland mesocosms to understand how the water properties of wetlands such as pH, dissolved oxygen content, water temperature, oxidation reduction potential, and nutrient concentrations are affected by different types of wetland plant. The floating plant lives on the water surface and can block light penetration; it exhibited the lowest water temperature and temperature difference between lower and upper layers. After the addition of contaminants, the dissolved oxygen (DO) concentration decreased abruptly but recovered continuously in all mesocosms; especially the submerged plants, which photosynthesize in water, showed the largest increases in DO and diel periodicity DO, as well as in pH value. The oxidation-reduction potential in both water and sediment were affected by the presence of wetland plants and plant type and the results suggest that various aspects of wetland biogeochemistry are affected by the presence and type of wetland plants. The total nitrogen and phosphorous concentrations in water decreased in the following order: Water only < Water + Soil < Floating Plants < Submerged Plants. Although both floating and submerged plants can control algal concentrations, the effect was more prominent for floating plants.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.338-344
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• 2003

The seismic analysis method of spent fuel storage structures for PHWR plant is introduced in comparison with the method for PWR plant. Investigating the structural characteristics of the storage structures, the former is vertically stacked fuel storage trays, while the latter is welded honeycomb type structure. However, as both structures are submerged and free standing, the analysis methods to anticipate the seismic response of both structures are complicated. For the better estimation of actual seismic response, how to model the dynamic properties and the structural behaviour is the key issue. In this paper, the overall procedures of the seismic modelling and stability check for seismic sliding and overturning of the two different storage structures are discussed in the viewpoint of analysis reliability

• Journal of Soil and Groundwater Environment
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• v.22 no.6
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• pp.12-21
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• 2017

A pot experiment was conducted to investigate the transfer of As and cationic heavy metals (Fe, Mn, Zn, Cd and Pb) from soil to rice plant in soil condition with submerged and drained. During the ninety-day monitoring period for soil solution, solubility of reducible elements such as As, Fe and Mn in submerged condition were higher than that of Zn. On the contrary, concentration of Zn in drained condition was higher than that of reducible elements. The concentration of As, Cd, Pb and Zn in rice plant (root, stem, leaf and grain) showed similar pattern with soil solution. The As concentration in each part of rice plant, which cultivated in drained condition, measured 56%~94% lower than those in submerged condition. However, the contents of cationic heavy metals (Cd, Pb and Zn) were represented the opposite result with As. These results are due to mobility of As and cationic heavy metals under different soil drainage conditions which represent oxidation and reduction. Thus soil drainage control can be used as acceptable passive treatment methods to reduce transfer of inorganic contaminants from soil to rice plant. However more detailed examination on soil condition conversion is needed, because yield of rice was decreased when it cultivated in drained condition only. It also needed when soil is contaminated by As and cationic heavy metal because single drainage condition cannot reduce transfer of both kinds of contaminants all.

• New & Renewable Energy
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• v.7 no.4
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• pp.37-41
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• 2011

This paper presents a Combined solar-wave Power Generation (CPG) concept that the CPG unit is maintained as buoyant at the level of sea water and it is also supported by a submerged tunnel, with the aim of supplying emergency electric power during the station blackout events of nuclear power plants. The CPG concept has been motivated from the 2011 Fukushima-Daiichi Accidents due to the loss of both offsite AC power and emergency diesel power caused by natural hazards such as earthquake and tsunami. The CPG is conceptualized by applying different types and different sites for emergency power generation, in order to reduce common cause failures of emergency power suppliers due to natural hazards. Thus, the CPG can provide a new mean for supplying emergency electric power during station blackout events of nuclear power plants. For this application, the CPG requirements are described with a typical configuration at the ocean side of a submerged tunnel.

• Journal of Ocean Engineering and Technology
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• v.31 no.2
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• pp.130-140
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• 2017

Typically, a submerged breakwater is one of the good scene-friendly coastal structures used to reduce wave energy and coastal erosion. However, sometimes, a submerged breakwater also has a negative aspect in that a strong rip current occurring around an open inlet due to a difference in mean water levels on the front and rear sides of the structure leads to scouring. Such scouring has a bad effect on its stability. In order to eliminate this kind of demerit, this study investigated four new types of submerged breakwaters with drainage channels. First, hydraulic experiments were performed the typical and new structures. Then, the wave height and mean water level distributions around the structures were examined using the experimental results. Finally, it was revealed that the new type of submerged breakwater could efficiently reduce the mean water level on its rear side. In particular, in the case of new-type submerged breakwater 2, an average reduction efficiency of 71.2% for the difference between the mean water levels at the front and rear sides was shown in comparison with the typical one.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.1
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• pp.116-122
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• 2007

A 2-step process for the safe disposal of chemical warfare agents(agent hydrolysis followed by incineration In the submerged-quench incinerator) was studied to obtain basic data for the design of pilot plant in the future. Sample materials used for the hydrolysis reaction were sarin(GB), sulfur mustard (HD), and methylphosphonic difluoride(DF). The hydrolysates of these materials were thermally destroyed in a submerged-quench incineration system. Experimental conditions for achieving destruction efficiency of 99.99% in both steps were established and phosphoric acid was recovered from the waste water when destroying DF hydrolysate in the incinerator. Treated water could be reused as process water for the agent hydrolysis.

• Microbiology and Biotechnology Letters
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• v.21 no.6
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• pp.609-614
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• 1993

The optimum conditions for the submerged mycelial culture of Lentinus edodes SR-1 were elucidated to be incubation temperature of 25C, initial pH 4.0, agitation of 300 rpm, inoculation of 10.0%(v/v), and aeration of 1.0 v/v/m in TGY medium. The optimum c/n ratio and economic yield coeffcient for the submerged mycelial culture were 13.1:1 and 0.45 respectively. As the plant growth hormones test, SCM medium containing 0.5ppm of 2,4-dicholorophenoxyacetic acid increased mycelial yield in 1.1%, but 6-benzylaminopurine was not effective.