• Journal of Navigation and Port Research
• /
• v.32 no.8
• /
• pp.637-643
• /
• 2008

When planning outfall system, the first target cif design is to maximize initial dilution of discharge effluent. To achieve the target effectively, the characteristics of mixing phenomenon between ambient and discharged water should be analyzed. Especially the analysis at the Near-Field-Region(NFR) as initial dilution zone should be preceded. Usually, the initial behavior of effluent through outfall system is rising toward the surface due to mixing with ambient water for heat discharge and sinking toward the bottom due to the difference of density for brine discharge. After mixed with eddies accompanied by the ambient water, the plumes are showing the same density and internal current pattern by advection and diffusion. Until recently, lots of studies are being carried out for the optimum design of outfall system. but it is difficult to find any studies of heat and brine discharge at the same time. Therefore, this study is hoped to provide some basic data for optimum design of outfall system.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.13 no.3
• /
• pp.245-253
• /
• 2001

Mixing zone characteristics of the wastewater effluents discharged from Sokcho ocean outfall have been investigated using an outfall mixing zone model which was developed on the basis of Huang et al.'s(1996) analysis method. The model was applied to Sokcho ocean outfall case and was used to simulate the concentration distribution of wastewater effluents using winter season's data, ie. daily effluent flowrate, ocean current and density stratification data which were measure for two months in the outfall area. Hourly concentration distribution of outfall effluent discharges was calculated and they were averaged for the period of 15 days which covers the ambient flow variability of the neap and the spring tidal currents. The results show that near-field dilution was relatively high with the minimum dilution of 130 for the winter season. The mixing zone was extended to the coastal beach area rather than offshore because of major direction of coastal currents. This may cause a deteriorating impact on coastal water quality, especially to the adjacent swimming beach area.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
• /
• 2001.06a
• /
• pp.1621-1621
• /
• 2001

The quality of sugarcane grown on the NE Australian tropical coast ($16^{\circ}$15'- $18^{\circ}$15' S Lat.) has declined markedly in the past seven years. This has been linked to dilution of mill-supply cane with increasing levels of non mature-stalk material consisting of leaves and sucker culms. The prime research objective was to examine the transition from the pre-harvest, in-field crop to harvested material sent for processing, in terms of quality and crop fraction proportions. A secondary objective was to quantify the effects of preharvest-season crop habit and culm condition on crop quality. Ten quadrat samples from each of 54 random crop sites (17 in 1999 and 37 in 2000), covering a wide range of variables (cultivar, crop class, and edaphic, topographic, climatic, and temporal factors) were collected immediately before harvest. Samples were partitioned into four fractions:- sound and unsound mature stalks (culms), sucker culms, and extraneous matter (leaves). Material harvested from each site was sampled and partitioned into four fractions:- sound and unsound billets (culm pieces), culm-spindle pieces, and leaf. In 2000, before harvest, 14 additional sites were sampled monthly, on three occasions, from March - June. Erect and non-erect culms were divided into sound and unsound classes. All samples were disintegrated and presented to a remote reflectance module of a scanning spectrophotometer using the BSES large cassette module. Near infra-red spectroscopic (NIS) analyses were developed for the rapid determination of quality components (Brix, commercial cane sugar (CCS), fibre, moisture, and polariscope reading). Calibrations for three material groups (culm (n = 639), non-culm (n = 496), and combined) were developed for all components using the 1999 data set. Two sub-sets (n = 178, and 190) of about 10% of the preharvest-season and harvest populations scanned in 2000 also were subjected to full routine laboratory analyses. The 1999 combined calibrations were excellent, but the culm calibrations produced consistently lower standard errors. Non-culm calibrations were marginally better than the combined for only CCS and pol. reading. Analysis of the 2000 culm data with calibrations using all 1999 and 2000 culm data resulted in better predictions relative to the 1999 culm calibrations. This also was true for the combined calibrations. Assessment of quality components in pre- and post-harvest sugarcane using NIS calibrations was more cost effective than using routine laboratory techniques. Outcomes from this NIS-facilitated research will have important economic consequences for the Australian sugarcane industry. Potential CCS present in mature culms is being discounted by dilution with leaves and sucker culms, threatening farm viability. The results question the efficacy of current harvesting technology. The CCS of harvested cane is improved only marginally over that of the in-field crop. Current harvesting technology requires either supplementary, innovative pre-mill processing or a design revolution to improve mill-supply cane quality, and therefore whole of industry economics. NIS-facilitated analyses, before the harvest season, highlighted the benefits of growing erect, sound crops. Loss of CCS then, can be minimized only by a combination of crop improvement and agronomic solutions, applied as part of sound on-farm management.

• Applied Biological Chemistry
• /
• v.39 no.6
• /
• pp.488-493
• /
• 1996

As a first step of pesticide runoff studies, runoff losses of captafol were measured under natural rainfall conditions in apple orchard area. The maximum concentration of captafol was 180 ppb at 5 th sampling period when the rainfall occurred within 24 hours after captafol was applied, and the concentration of samples from other periods was below than 20 ppb. Total runoff loss of captafol was below 0.1%. About 10 fold of dilution factor was observed at the merging point with stream near outlet from orchard and about 50 fold was observed at the next merging point which is located further down. Therefore, captafol will not harm the aquatic organisms due to dilution factor$(10{\sim}50\;fold)$ and rapid hydrolytic degradation rate even when it was run off into a stream nearby.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.1
• /
• pp.153-160
• /
• 2021

Nitrous oxide is a global warming substance and is known as the main cause of the destruction of the ozone layer because its global warming effect is 310 times stronger than carbon dioxide, and it takes 120 years to decompose. Therefore, in this study, we investigated the characteristics of NOx emission from N2O reduction by thermal decomposition of N2O. Bunsen premixed flames were adopted as a heat source to form a high-temperature flow field, and the experimental variables were nozzle exit velocity, co-axial velocity, and N2O dilution rate. NO production rates increased with increasing N2O dilution rates, regardless of nozzle exit velocities and co-axial flow rates. For N2O, large quantities were emitted from a stable premixed flame with suppressed combustion instability (Kelvin Helmholtz instability) because the thermal decomposition time is not sufficient with the relatively short residence time of N2O near the flame surface. Thus, to improve the reduction efficiency of N2O, it is considered effective to increase the residence time of N2O by selecting the nozzle exit velocities, where K-H instability is generated and formed a flow structure of toroidal vortex near the flame surface.

• Horticulture, Environment, and Biotechnology : HEB
• /
• v.59 no.6
• /
• pp.775-786
• /
• 2018

To test the hypothesis that humic acid (HA), anaerobically digested pig slurry filtrate (APS), and their combination would differently affect the chemical speciation and extractability of metals (cadmium, copper, and zinc) and their uptake by plants, we conducted a pot experiment using wormwood in two texturally contrasting soils (sandy loam and clay loam) collected from a field near an abandoned Cu mine. Four treatments were laid out: HA at $ 23.5g\;kg^{-1}$ (HA), APS at $330mL\;kg^{-1}$ (APS), HA at $ 23.5g\;kg^{-1}$ and APS at $330mL\;kg^{-1}$ (HA + APS), and a control. Each treatment affected the chemical speciation and mobility of the metals, and thereby resulting in variable patterns of plant biomass yield and metal uptake. The APS supported plant growth by increasing nutrient availability. HA supported or hindered plant growth by impacting the soil's water and nutrient retention capacity and aeration, in a soil texture-dependent manner, while consistently enhancing the immobilization of heavy metals. Temporal increases in whole-plant dry matter yield and metal accumulation suggested that the plants were capable of metal hyperaccumulation. The results were discussed in terms of the mobility of metals and plant growth and corroborated by the $^{15}N$ recovery of soil- and plant-N pools under H and HS treatments. Therefore, for effective phytoremediation of polluted soils, an appropriate combination of plant growth promoters (APS) and chelating agents (HA) should be predetermined at the site where chemical stabilization of pollutants is desired.

• Atmosphere
• /
• v.33 no.4
• /
• pp.343-354
• /
• 2023

Turbulence produced on roadways is one of the major factors determining the dilution rates at the initial stage of traffic emissions of air pollutants and, thus, the distribution of air pollutants near the roadways. Field experiments were conducted on Gyeongbu Highway, one of the busiest highways in Korea, for 4~7 days in winter, spring, and summer. Two three-dimensional ultrasonic anemometers were installed on both sides of the highway to estimate turbulence intensities (vertical wind fluctuation and kinetic turbulence energy) induced by the roadway. Roadway-induced turbulence consists of three components: structural road-induced turbulence (S-RIT), thermal road-induced turbulence (T-RIT), and vehicle-induced turbulence (VIT). The contribution of T-RIT to the total RIT was insignificant (less than 10%), and the majority of RIT was S-RIT (by the highway embankment) and VIT. In this study, we propose the empirical relationships of VIT as a function of traffic density and wind speed under free-flow traffic conditions. Although this empirical relationship appears to underestimate the VIT, it can be applied to the air quality models easily because the relationship is simple and only needs readily obtainable input variables (wind speed and traffic information).

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11c
• /
• pp.784-791
• /
• 2000

To improve the uniformity of slurry spreading and to reduce the odor problem, a hose slurry spreader was developed, which spread the slurry near to the surface of the soil. First, the uniformity of slurry spreading was investigated. The best result of 8.1 ％ CV was obtained at the rotor speed of 250 rpm than any other speeds for the swine slurry, which contains 13.6% of dry matter. In case of dairy cattle slurry, which contains 8.2% of dry matter, the uniformity has the best result of CV 7.2% by high rotor speed of 330 rpm. A high speed of rotor has built a sufficient pressure in the distributor and discharged a uniform quantity of slurry through the hoses. Therefore, in practical use one should work with rotor speed over 300 rpm to maximize the uniformity of slurry spreading. Second, odor test was done with the swine slurry. While the conventional spreader shows ∑ value 440, the hose slurry spreader and its combination of disk harrow show ∑ value 258 and 184 respectively. With the air dilution sensual test and a 3-point odor bag, the conventional spreader shows 66.9 or 35.4 point and by the hose slurry spreader is 9.7 or 11.1 point. So, the developed spreader was found to have a greater effect on the reduction of odor problem. Finally, it is recommended to spread certain amount of the slurry for paddy field equivalent to the chemical fertilizer based on the N-content. It means 22 tons of swine slurry per ha. Since most of the livestock farms possess less arable land, a system of linking farms is necessary to utilize the slurry crossover the farms. The cost of slurry utilization including filling, transport spreading and brokerage is 3200-6800 Won/㎥ in accordance with the transport distance.

• Journal of Environmental Impact Assessment
• /
• v.22 no.2
• /
• pp.135-145
• /
• 2013

The recycling of coal bottom ash generated from coal power plants in Korea has been limited due to heterogenous characteristics of the materials. The most common management option for the ash is disposal in landfills (i.e. ash pond) near ocean. The presence of large coarse and fine materials in the ash has prompted the desire to beneficially use it in an application such as fill materials. Prior to reuse application as fill materials, the potential risks to the environment must be assessed with regard to the impacts. In this study, a total of nine test cells with bottom ash samples collected from pretreated bottom ash piles and coal ash pond in a coal-fired power plant were constructed and operated under the field conditions to evaluate the leachability over a period of 210 days. Leachate samples from the test cells were analyzed for a number of chemical parameters (e.g., pH, salinity, electrical conductance, anions, and metals). The concentrations of chemicals detected in the leachate were compared to appropriate standards (drinking water standard) with dilution attenuation factor, if possible, to assess potential leaching risks to the surrounding area. Based on the leachate analysis, most of the samples showed slightly high pH values for the coal ash contained test cells, and contained several ions such as sodium, potassium, calcium, magnesium, chloride, sulfate, and nitrate in relatively large quantities. Three elements (aluminum, boron, and barium) were commonly detected above their respective detection limits in a number of leachate samples, especially in the early leaching period of time. The results of the test cell study indicate that the pollutants in the leachate from the coal ash test cells were not of a major concern in terms of leaching risk to surface water and groundwater under field conditions as fill materials. However, care must be taken in extending these results to actual applications because the results presented in this study are based on the limited field test settings and time frame. Structural characteristics and analysis for coal bottom ash may be warranted to apply the materials to actual field conditions.

• Proceedings of the KSEEG Conference
• /
• 2002.06a
• /
• pp.81-100
• /
• 2002

While most of regulatory communities in abroad recognize ' 'natural attenuation " to include degradation, dispersion, dilution, sorption (including precipitation and transformation), and volatilization as governing Processes, regulators prefer "degradation" because this mechanism destroys the contaminant of concern. Unfortunately, true degradation only applies to organic contaminants and short- lived radionuclides, and leaves most metals and long-lived radionuclides. The natural attenuation Processes may reduce the potential risk Posed by site contaminants in three ways: (i)contaminants could be converted to a less toxic form througy destructive processes such as biodegradation or abiotic transformations; (ii) potential exposure levels may be reduced by lowering concentrations (dilution and dispersion); and (iii) contaminant mobility and bioavailability may be reduced by sorption to geomedia. In this review, authors will focus will focul on "sorption" among the natural attenuation processes of hazardous inorganic contaminants including radionuclides. Note though that sorption and transformation processes of inorganic contaminants in the natural setting could be influenced by biotic activities but our discussion would limit only to geochemical reactions involved in the natural attenuation. All of the geochemical reactions have been studied in-depth by numerous researchers for many years to understand "retardation" process of contaminants in the geomedia. The most common approach for estimating retardation is the determination of distrubution coefficiendts ($K_{d}$) of contaminants using parametric or mechanistic models. As typocally used in fate and contaminant transport calculations such as predictive models of the natural attenuation, the $K_{d}$ is defined as the ratio of the contaminant concentration in the surrounding aqueous solution when the system is at equilibrium. Unfortunately, generic or default $K_{d}$ values can result in significant error when used to predict contaminant migration rate and to select a site remediation alternative. Thus, to input the best $K_{d}$ value in the contaminant transport model, it is essential that important geochemical processes affecting the transport should be identified and understood. Precipitation/dissolution and adsorption/desorption are considered the most important geochemical processes affecting the interaction of inorganic and radionuclide contaminants with geomedia at the near and far field, respectively. Most of contaminants to be discussed in this presentation are relatively immobile, i.e., have very high $K_{d}$ values under natural geochemical environments. Unfortunately, the obvious containment in a source area may not be good enough to qualify as monitored natural attenuation site unless owner demonstrate the efficacy if institutional controls that were put in place to protect potential receptors. In this view, natural attenuation as a remedial alternative for some of sites contaminated by hazardous-inorganic components is regulatory and public acceptance issues rather than scientific issue.