• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.259-262
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• 1999

In underground reinforced concrete structures, such as drainage structure, water and chloride ion penetrated into concrete through the cracks of concrete and its permeable property, cause the corrosion of reinforcing steel bar, which accelerates the expansive cracks and deterioration of concrete. It is necessary to control those deterioration of underground structure by improving its permeability and durability through the reasonable solutions in design, construction and materials. In the present study, fly ash concrete, which has good material properties in long-term period, was compared and studied with plain concrete using ordinary portland cement in terms of fundamental mechanical properties, permeability, drying shrinkage and durability. Also, the mix design and field test of low permeable concrete using fly ash were performed. From this study, fly ash concrete can control the penetration of water and chloride ion effectively by forming dense micro-structure of concrete. Therefore, fly ash concrete may increase the long-term function, performance and serviceability of underground structures.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.35-40
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• 2006

In recent years, there's been strong demand for seawalls that havea gentle slope and permeability that serveswater affinity and disaster prevention from wave attack. The aim of this study is to examine wave transformation, including wave run-up that propagates on the coastal structures. A numerical model based on the weak nonlinear dispersive Boussinesq equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable layer, is developed. The applicability of this numerical model is examined through Deguchi and Moriwaki's hydraulic model test on the permeable slopes. From this study, it is found that the proposed numerical model can predict wave transformation and run-up on the gentle slope with a permeable layer, but can't show accurate results for slopes steeper than about 1:10.

• Journal of Environmental Science International
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• v.24 no.4
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• pp.449-459
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• 2015

The depth of low permeable layer in Jeju Island was analyzed using the geologic columnar section data. The highest low permeable layer was found in center of Mt. Halla and the deepest area was in eastern part of Jeju Island. The study area, Seongsan watershed, is located in the eastern part of Jeju where the low permeable layer showing deep in a northward direction. Based on this analysis, the MODFLOW modeling was performed for groundwater flow of Seongsan watershed. The boundary of Seongsan watershed was set up as a no-flow and the modeling result showed the difference -0.26~0.62 m compared to the observed groundwater level. Meanwhile, MODFLOW model results considering low permeable layer showed -0.26~0.36 m differences compared to groundwater level and indicated more accurate than no-flow method result. Therefore, to interpret the groundwater flow over Seongsan watershed, comprehensive consideration including the low permeable layer distribution below the basalt layer is needed.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.1-5
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• 2002

In the past, ports have been mainly developed in natural harbors but nowadays ports are built wherever they can be economically justified. Therefore, construction of breakwater in area that establishment of structure is disadvantageous is risen according to the change of conditions to the location for ports. In case of building gravity breakwater in such point, need that plane shapes of more reasonable section permitting wave overtopping is necessary. One of the earliest methods for solving unsteady incompressible flow including free surfaces is the MAC(Marker And Cell) method by Harlow and Welch (1965). Recently. VOF(Volume Of Fluid) method to improve several drawbacks of MAC method is suggested by Hirt and Nichols(1981) and utilized extensively in fields of hydrodynamics. Wave overtopping phenomenon is simulated including wave breaking for permeable breakwater by numerical analysis and investigated features of wave overtopping behind structure using VOF method.

• Journal of Ocean Engineering and Technology
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• v.14 no.3
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• pp.1-10
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• 2000

In order to effective manage the construction, disaster prevention plan and the harbor tranquility control, meteorological and sea-state characteristics around Cheju Island have been analyzed. Using results and damage examples of the port facilities under severe sea conditions, a reasonable construction control plan considering the regional characteristics of the sea-state and winds was proposed. That is, in northern part of Cheju Island, the construction work is affected mainly by the winter storms, while the typhoon mainly affects the southern part port facilities during summer to Autumn. Considering their typical characteristics, it is strongly suggested that the main construction work should be carried out during April to July in the northern part, and it should be made during October to next July in the southern part of the island. A permeable TTP mounded breakwater was constructed to protect severe waves as a temporal structure under the long-term development plan in Sogipo port. The transmission characteristics of the structure was discussed using the experimental results. The results show that the transmission coefficient $K_{t}$ is over 20% of incident waves, which cause many problems in the cargo handling in relation to harbor tranquility. In conclusion, this kind of permeable structure can be used only as a temporal structure for the disaster prevention under the construction process. It causes many problems in harbor tranquility if it is used as a permanent harbor structures.s.

• Korean Journal of Agricultural Science
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• v.37 no.2
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• pp.277-283
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• 2010

Research on permeable pavement like asphalt and concrete pavement with porous structure has been increasing due to environmental and functional need such as reduction of run off and flood. This study was performed to evaluate void ratio, permeability coefficient, and compressive strength of permeable polymer concrete (PPC) using crushed and recycled coarse aggregate that is obtained from waste concrete. Also, 6 mm length of polypropylene fiber was used to increase toughness and interlocking between aggregate and aggregate surrounded by binder. Binder and filler used were unsaturated polyester resin and CaCO3, respectively. The mix proportions were determined to satisfy the requirement for the workability and slump according to aggregate sizes 5~10 mm. In the test results, regardless of kinds of aggregates and fiber contents, the void ratio, permeability coefficient and compressive strength of all types of PPC showed the higher than the criterion of porous concrete that is used in permeable pavement in Korea. Also, strengths of PPC with increase polypropylene fiber volume fraction showed slightly increased tendency due to increase binder with increase of fiber volume fraction. Accordingly, polypropylene fiber and recycled coarse aggregate can be used for permeable pavement.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.453-456
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• 2006

To examine the effect of shape and crest width variation of a permeable submerged breakwater on the wave energy dissipation, Two-Dimensional numerical model with Large Eddy Simulation, which is able to simulate directly WAve Structure Seabed interaction (hereafter, LES-WASS-2D) has been newly developed. A good agreement has been obtained by the comparison between the existing experimental results and LES-WASS-2D model's results for the permeable submerged breakwater. Moreover, based on the LES-WASS-2D model, the wave energy dissipation due to a permeable submerged breakwater are discussed for regular and irregular waves with relation to its crest width and shape.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.172-179
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• 2001

A numelical model has been developed for the permeable coastal structures to simulate hydraulic characteristics on the permeable slopes, which interact with internal flow field of the structures. The model includes hydraulics in the porous medium. Numerical model was calibrated using hydraulic model experiments performed in 2-D wave flume in the Institute of Orean Hydraulics in PKNU. Good agreement were obtained with the model which employed inertia resistance term than with the conventional model, PBREAK.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.69-77
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• 2010

Research on permeable pavement like asphalt and concrete pavement with porous structure has been increasing due to environmental and functional need such as reduction of run off and flood, and increase and purification of underwater resource. This study was performed to evaluate permeability, strengths and durability of permeable polymer concrete (PPC) using recycled aggregate that is obtained from waste concrete. Also, 6mm length of polypropylene fiber was used to increase toughness and interlocking between aggregate and aggregate surrounded by binder. In the test results, regardless of kinds of aggregates and fiber contents, the compressive strength and permeability coefficient of all types of PPC showed the higher than the criterion of porous concrete that is used in permeable pavement in Korea. Also, strengths of PPC with increase polypropylene fiber volume fraction showed slightly increased tendency due to increase binder with increase of fiber volume fraction. The weight reduction ratios for PPC after 300 cycles of freezing and thawing were in the range of 1.6~3.8 % and 2.2~5.6 %, respectively. The weight change ratio was very low regardless of the fiber volume fraction and aggregates. The weight reduction ratios of PPC with fiber and aggregate were in the range of 1.3~2.7 % and 2.2~3.2 % after 13 weeks and was very low regardless of the fiber volume fraction and aggregates.

• Journal of Korea Water Resources Association
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• v.49 no.1
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• pp.51-60
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• 2016

The purpose of this study is to examine the control function of discharged flow due to the shape and plane arrangement of permeable submerged breakwater. For the discussion on it in detail, 3-dimensional numerical model based on PBM (Porous Body Model), which is able to simulate directly interaction of Fluid Permeable structure Seabed has been used to simulate water discharge in a NWT (Numerical Water Tank). To verify the applicability, LES-WASS-3D is analyzed comparing to the experimental result about propagation characteristics of dam-break wave through a permeable structure. Using the results obtained from numerical simulation, the effects of the shape and plane arrangement of submerged breakwater on reducing velocity and flow induction have been discussed related to the mean flow distribution and vertical distributions of horizontal velocities around ones.