• Journal of the Society of Naval Architects of Korea
• /
• v.40 no.3
• /
• pp.29-36
• /
• 2003

In rough seas, bow-flare regions of the fine ships (container ship and PCC) are subject to high impact pressures due to the bow-flare slamming. And many ships suffer structural damages in that region, even though they were built under the bow structure strengthening rules of the ship classes. So, a new design method for bow-flare structure is highly required. In this paper, a new prediction method of the bow-flare impact pressure (in terms of equivalent static pressure) acting on the fine ships' bow is presented. This method is based on the 11 fine ships' damage analysis and the mechanisms of water entry impact and breaking wave impact. Calculation results of the bow-flare impact pressure and the shell plate thickness are shown and discussed. Through the example calculations, it was found that the present method is useful for the structure design of the fine ships' bow.

• Journal of Environmental Science International
• /
• v.14 no.10
• /
• pp.937-944
• /
• 2005

Presently, aquatic plants are used for the water purification in inland water. This study was carried out to investigate the water purification effect of aquatic plants, Oenanthe javanica and Typha angustata, The experiment was conducted in outdoor flowing water was conducted for ten days, Water quality was measured in terms of water temperature, COD(chemical oxygen demand), SS(suspended solids), Total N, Total P. The results of field experimentation showed that hydraulic retention time was the earliest in July and August 2003, and there were not any particular changes of monthly water temperature in inflow water and outflow water. As we look at the changes taken place in inflow water and outflow water throughout the whole experiment period, the change of water quality in summer was salient, especially SS removal ratio showed distinguished change as $25\%$, when the pebble filter and aquatic were attached to it. The removal rate of COD, total N total P were $14,7\%,\;8\%\;and\;9\%$, respectively. In relating the length of water extension to the change in water quality, the water quality tended to get lower generally in proportion to hydraulic retention time.

• Journal of Environmental Impact Assessment
• /
• v.26 no.6
• /
• pp.524-537
• /
• 2017

Post-Environmental impact investigation(Post-EII) plays an important role in investigating and reducing the environmental impacts of construction operations in South Korea. To date, it has been estimated that the results for Post-EII showed the low reliability; however, understanding those reliability has rarely been studied. We investigated the effect on water qualities by construction operations of the quarry mine, training center, and golf club in South Korea. In addition, the results of water quality analysis in this study were compared and analyzed with those in Post-EII. Treated wastewater in a quarry mine showed high concentrations of biochemical oxygen demand(BOD), suspended solid(SS), total nitrogen(T-N), and total phosphorus(T-P). Compared with the water quality results between this study and Post-EII, the concentrations of BOD, SS, T-N, and T-P in the treated wastewater were higher than the interquartile range(IQR) as well as the range of the results from minimum to maximum in Post-EII(p<0.05). The concentrations of BOD, SS, T-N, and T-P in treated wastewater were high under constructions in a training center. The concentrations of BOD and SS exceeded the consultation standard for the treated wastewater. These concentrations showed the significant difference with the IQR and the range from minimum to maximum of the water quality results in Post-EII(p<0.05). Therefore, the management and monitoring for water quality should be conducted in the treated wastewater by of construction operations. In addition, the alternative to enhance the reliability for the water quality results should be sought in Post-EII.

• Journal of Environmental Impact Assessment
• /
• v.3 no.2
• /
• pp.33-45
• /
• 1994

Water quality of Chongju and Daejeon Water Intake Tower Region, embayments in Daechong Reservoir was found to be worse than that of main lake after analysis of water which were sampled during April, July, October in 1993. Concentration of COD and SS at those two water intake tower sites were 2.8-5.6 mg/l and 2.2-3.2 mg/l, higher than that of main lake. T-N concentration of those two sites was 1.1-1.9 mg/l similar to that of main lake, and T-P concentration of those two sites was 0.14-0.18 mg/l, higher than that of main lake. This study used water quality model of embayment which can analyse pollutant loads from stream and surrounding land use, advection, decay, and diffusion transport between embayment and main lake. The model can predict water quality of embayment according to the change of pollutant load, water elevation of embayment, quantity of water intake in order to suggest water quality management. This study suggests embayment water quality management alternatives, 1) construction of waste water treatment facilities at embayment and main lake for the decrease of pollutant loading, 2) water intake at main lake less polluted or eutrophicated than embayment, and 3) outflow elevation selection for polluted hypolimnion water outflow during stratification.

• Journal of Korean Society on Water Environment
• /
• v.25 no.4
• /
• pp.507-514
• /
• 2009

In this study, a dynamic modeling scheme is presented to describe the probabilistic structure of soil water and plant water stress index under stochastic precipitation conditions. The proposed model has the form of the Fokker-Planck equation, and its applicability as a model for the probabilistic evolution of the soil water and plant water stress index is investigated under a climate change scenario. The simulation results of soil water confirm that the proposed soil water model can properly reproduce the observations and show that the soil water behaves with consistent cycle based on the precipitation pattern. The simulation results of plant water stress index show two different PDF patterns according to the precipitation. The simple impact assessment of climate change to soil water and plant water stress is discussed with Korean Meteorological Administration regional climate model.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.189-189
• /
• 2016

To generate information that contributes to climate change risk management, it is important to perform a precise assessment on the impact in diverse aspects. Considering this academic necessity, Japanese government launched continuous research project for the climate change impact assessment, and one of the representative project is Program for Risk Information on Climate Change (Sousei Program), Theme D; Precise Impact Assessment on Climate Change (FY2012 ~ FY2016). In this research program, quantitative impact assessments have been doing from a variety of perspectives including natural hazards, water resources, and ecosystems and biodiversity. Especially for the natural hazards aspect, a comprehensive impact assessment has been carried out with the worst-case scenario of typhoons, which cause the most serious weather-related damage in Japan, concerning the frequency and scale of the typhoons as well as accompanying disasters by heavy rainfall, strong winds, high tides, high waves, and landslides. In this presentation, a framework of comprehensive impact assessment with the worst-case scenario under the climate change condition is introduced based on a case study of Theme D in Sousei program There are approx. 25 typhoons annually and around 10 of those approach or make landfall in Japan. The number of typhoons may not change increase in the future, but it is known that a small alteration in the path of a typhoon can have an extremely large impact on the amount of rain and wind Japan receives, and as a result, cause immense damage. Specifically, it is important to assess the impact of a complex disaster including precipitation, strong winds, river overflows, and high tide inundation, simulating how different the damage of Isewan Typhoon (T5915) in 1959 would have been if the typhoon had taken a different path, or how powerful or how much damage it would cause if Isewan Typhoon occurs again in the future when the sea surface water temperature has risen due to climate changes (Pseudo global warming experiment). The research group also predict and assess how the frequency of "100-years return period" disasters and worst-case damage will change in the coming century. As a final goal in this research activity, the natural disaster impact assessment will extend not only Japan but also major rivers in Southeast Asia, with a special focus on floods and inundations.

• Journal of Environmental Impact Assessment
• /
• v.19 no.1
• /
• pp.49-57
• /
• 2010

The objective of the research is to analyze changing trend of water discharge in precipitation, according to changing land use, through an environment-friendly urban development method called LID. The study chose S1 basin (Separated Sewer districts) in Cheongju region for survey. Among LID methods, relatively more applicable methods of green rooftop space and parking lot with permeable material were selected to construct plausible scenarios. Curve Number (CN) value was calculated due to land use patterns in each scenario, and SWMM model simulation were conducted during 2008 for comparative analysis. For Case 1, only parking lot with permeable material was applied to the scenario. Green rooftop space I and II were applied to Case 2 and 3 respectively. For Case 4 and 5, green rooftop space I and II were applied, in addition to parking lot with permeable material, Calculation of CN value showed that for S1 basin, the value was 88.1 (prior to scenario application), 86.5 (Case 1), 81.9 (Case 2), 68.5 (Case 3), 80.4 (Case 4) and 67.2 (Case 5). Changing pattern of rain water discharge was analyzed for each scenario. For Case 1, the change was not remarkable before and after application of scenario. In Case 2 and 4, the impact of rain water discharge as source of pollutant fell to 20~30%. The rate dropped to 30~50% in Case 3 and 5 respectively. The result demonstrates that the amount of rain water discharge, amount and frequency of sewer overflow, frequency of rain water discharge, and pollution load decreased in accordance with declining CN value in each scenario. In installing green rooftop space, the effect was twice greater when rain water discharge was directly infiltrated into soil.

• Journal of Korean Society on Water Environment
• /
• v.25 no.6
• /
• pp.821-831
• /
• 2009

The study was aimed to assess the expected impact of climate change on the water cycle and soil losses in Daecheong Reservoir watershed, Korea using the Soil and Water Assessment Tool (SWAT) that was validated for the watershed in a previous study. Future climate data including precipitation, temperature and humidity generated by introducing a regional climate model (Mesoscale Model Version 5, MM5) to dynamically downscale global circulation model (European Centre Hamburg Model Version 4, ECHAM4) were used to simulate the hydrological responses and soil erosion processes in the future 100 years (2001~2100) under the Special Report on Emissions Scenario (SRES) A1B. The results indicated that the climate change may increase in the amount of surface runoff and thereby sediment load to the reservoir. Spatially, the impact was relatively more significant in the subbasin Bocheongcheon because of its lower occupation rate of forest land compared to other subbasins. Seasonally, the increase of surface runoff and soil losses was more significant during late summer and fall season when both flood control and turbidity flow control are necessary for the reservoir and downstream. The occurrence of extreme turbidity flow events during these period is more vulnerable to reservoir operation because the suspended solids that remained water column can be resuspended by vertical mixing during winter turnover period. The study results provide useful information for the development of adaptive management strategy for the reservoir to cope with the expected impact of future climate change.

• Journal of the Korean Wood Science and Technology
• /
• v.34 no.2
• /
• pp.10-21
• /
• 2006

Recycled polypropylene (RPP) - Wood Saw Dust (WSD) composites with and without acetylation of filler were produced at different filler loading (15%, 25%, 35% and 45% w/w) and filler size (300, 212 and $100{\mu}m$). The RPP-WSD was compounded using a Haake Rheodrive 500 twin screw compounder at $190^{\circ}C$ at 8 MPa for 30 minutes. The mechanical properties and water absorption properties of modified and unmodified WSD-PP composites were investigated. Acetylation of WSD improved the mechanical and water absorption characteristic of composites. The decrease of filler size (300 to $100{\mu}m$) of the unmodified and acetylated WSD showed increase of tensile strength and impact properties. The composites exhibited higher tensile modulus properties as the filler loading increased (15% to 45%). However tensile strength, elongation at break and impact strength showed the opposite phenomenon. Water absorption increased as the mesh number and filler loading increased. With acetylation, lower moisture absorption was observed as compared to unmodified WSD. The failure mechanism from impact fracture of the filler-matrix interface with and without acetylation was analyzed using Scanning Electron Microscope (SEM).

• Ecology and Resilient Infrastructure
• /
• v.3 no.2
• /
• pp.130-133
• /
• 2016

The increase in impervious surfaces due to urban development has caused a groundwater drawdown through the reduction of underground infiltration, flood disaster due to increased rainfall runoff and environmental pollution in higher pollutant concentrations of first flush rainwater. As an alternative to these problems, the needs of low impact development (LID) techniques is increasing in urban areas. In this study, the restoration efficiency of water cycle was assessed at a residential site development applied with the LID rainwater management system. The results of monitoring the water cycling showed that the efficiency of water cycle of LID rainwater management system was improved 41% more than that of conventional methods.