• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.446-452
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• 2010

Five year term study from 2002 to 2006 was carried out to examine the effects of continuous long-term application of swine liquid manure on soil chemical properties including heavy metal contents and yield of tomato (Lycopersicon esculentum) and cucumber (Cucumis sativus L.) in a greenhouse. Treatments were conventional chemical fertilizers and three types of swine slurry; Slurry composting and biofiltration (SCB), Thermophilic aerobic oxidation (TAO), and Bio-mineral water (BMW). Total nitrogen level of the SCB, TAO, and BMW was 0.47%, 0.09%, and less than 0.01%, respectively. The heavy metal contents of the three liquid manures were much lower than the Korean regulation level. The soil phosphorus, potassium, and heavy metal contents after five year continuous application of swine slurry were not significantly higher than those of chemical fertilizer use. Contents of heavy metals in leaves of the crops did not show significant difference among treatments. The levels of copper and zinc, plant essential elements, in leaves were in the range of optimum plant growth. Yields of tomato and cucumber for swine liquid manures were not significantly different from that of chemical fertilizer. The results implied that the three types of swine slurry may not deteriorate soil chemical properties including phosphate and trace elements in greenhouse soils when they are applied as a basal fertilization at a recommended nitrogen rate based on soil testing.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.51-51
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• 2010

Recently just as in the automobile industry, shipbuilders also try to reduce material consumption and weight in order to keep operating costs as low as possible and improve the speed of production. Naturally industry is ever searching for welding techniques offering higher power, higher productivity and a better quality. Therefore it is important to have a details research based on the various welding process applied to steel and other materials, and to have the ability both to counsel interested companies and to evaluate the feasibility of implementation of this process. Submerged-arc welding (SAW) process is usually used about 20% of shipbuilding. Similar to gas metal arc welding(GMAW), SAW involves formation of an arc between a continuously-fed bare wire electrode and the work-piece. The process uses a flux to generate protective gases and slag, and to add alloying elements to the weld pool and a shielding gas is not required. Prior to welding, a thin layer of flux powder is placed on the work-piece surface. The arc moves along the joint line and as it does so, excess flux is recycled via a hopper. Remaining fused slag layers can be easily removed after welding. As the arc is completely covered by the flux layer, heat loss is extremely low. This produces a thermal efficiency as high as 60% (compared with 25% for manual metal arc). SAW process offers many advantages compared to conventional CO2 welding process. The main advantages of SAW are higher welding speed, facility of workers, less deformation and better than bead shape & strength of welded joint because there is no visible arc light, welding is spatter-free, fully-mechanized or automatic process, high travel speed, and depth of penetration and chemical composition of the deposited weld metal. However it is difficult to application of thin plate according to high heat input. So this paper has been focused on application of the field according to SAW process for thin plate in ship-structures. For this purpose, It has been decided to optimized welding condition by experiments, relationship between welding parameters and bead shapes, mechanical test such as tensile and bending. Also finite element(FE) based numerical comparison of thermal history and welding residual stress in A-grade 3.2 thickness steel of SAW been made in this study. From the result of this study, It makes substantial saving of time and manufacturing cost and raises the quality of product.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.271-281
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• 2014

BACKGROUND: Application of the transfer functions derived from local soil data is necessary in order to develop proper management protocols for agricultural soils contaminated with heavy metals through phytoavailability control of the heavy metals. The aim of this study was to derive the transfer functions of Korean agricultural soils affected by the abandoned mining sites and evaluate suitability of the derived transfer functions. METHODS AND RESULTS: 142 agricultural soils affected by the abandoned mining sites were collected and analyzed. Two extraction methods, including 1 M $NH_4NO_3$ extraction and 0.01 M $Ca(NO_3)_2$ extraction were applied to determine phytoavailable metal pools in soils. Multiple stepwise regression of phytoavailable metal pools against the corresponding total metal concentration and soil properties was conducted to derive suitable transfer functions for estimating phytoavailable heavy metal pools. Applicability of the derived transfer functions was examined by calculating NME and NRMSE. CONCLUSION: Soil pH and organic matter were valid variables for derivation of the transfer functions which were applicable for estimating phytoavailable metal concentrations in the soils being contaminated by heavy metals. In addition, it was confirmed that transfer functions need to be developed based on local soil conditions to accurately estimate heavy metal-phytoavailability.

• Journal of the Society of Disaster Information
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• v.14 no.2
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• pp.154-164
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• 2018

Purpose: Recent climate change makes weather-related disasters such as summer storms, heavy rains, winter snowfall disasters, and extreme cold temperature increase in trend. Heavy snowfall disasters requires speedy response due to various effects to traffic flows, buildings, and infrastructure. Heavy snowfall disaster response of South Korea is insufficient, even though heavy snowfall disasters affect urban safety. There have been lack of policy studies for heavy snowfall disasters. Method: This research analyzes case studies and explores implications using Information system technologies to snow removal vehicles and equipments for speedy snow removal during the heavy snowfall disasters. Results: Information system technology attachment to snow removal equipments can identify locations of snow removal vehicles and equipments for emergency period to support snow removal of adjacent jurisdictions. Conclusion: Case studies of this research can be further used for efficient application of snow removal tools of local governments.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.751-756
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• 2012

In this study, a heavy-metal stabilization treatment using stabilizing agents derived from waste resources was utilized on Incheon North Port range sediment contaminated with Pb, Zn, and Cu. Both calcined red mud (5%, 10%, and 15% w/w) and oyster shell (5%, 10%, and 15% w/w) were applied for a wet-curing duration of 15 days. From the sequential extraction results, the oxide and organic fraction of heavy metals (Pb, Zn, and Cu) were observed strongly in the contaminated sediment. However, the fraction of heavy metal in the stabilized sediment was higher than the organic and residual fraction, in comparison to the contaminated sediment. Moreover, the leaching of heavy metals was reduced in the stabilized sediment, compared with the contaminated sediment. From these results, red mud and oyster shell were shown to be potential stabilizers of heavy metals in contaminated sediment.

• Journal of Soil and Groundwater Environment
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• v.16 no.5
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• pp.9-17
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• 2011

Positive effect of multiple-PGPR (Plan Growth Promoting Rhizobacteria), isolated from heavy metal contaminated soil, on the germination of Barnyard grass (Echinochloa crus-galli var. frumentacea) was quantitatively estimated in 5 heavy metal (Cd, As, Ni, Cu, and Pb) contaminated liquid medium. The $EC_{50}$ value for respective heavy metal was estimated by TSK (Trimmed Speraman-Karber) model based on germination rate. The results showed overall increase in $EC_{50}$ with PGPR inoculation. The $EC_{50}$ value increased 1.4% from 96.0 mg/L (control) to 97.4 mg/L (PGPR-treated) in As contaminated medium. In Ni contaminated medium, the $EC_{50}$ value increased 31.9% from 148.0 mg/L (control) to 195.2 mg/L (PGPR-treated), while the $EC_{50}$ showed 4.8% increase from 63.4 mg/L (control) to 66.5 mg/L (PGPR-treated) in Cu medium. Overall seedling growth was stronger in the PGPR treated seeds than that in the control, but positive effect on seedling growth was not conspicuous. At effective concentration of 100 mg/L, the average seedling length of the PGPR treatment in As, Cd, Cu, and Ni medium, respectively, was 1.13, 0.14, 0.40, and 0.06 cm longer than that in the control. However, the increase of seedling growth was statistically insignificant (p < 0.05). These results suggest that inoculation of the isolated-PGPR exerts positive effects on seed germination by reducing heavy metal toxicity and can be an effective tool for application of phytoremediation on heavy metal contaminated soils.

• Membrane and Water Treatment
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• v.11 no.1
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• pp.11-23
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• 2020

The effectiveness of in situ sediment capping as a technique for heavy metal risk mitigation in Hyeongsan River estuary, South Korea was studied. Sites in the estuary were found previously to show moderate to high levels of contamination of mercury, methylmercury and other heavy metals. A 400 m × 50 m section of the river was selected for a thin layer capping demonstration, where the total area was divided into 4 sections capped with different combinations of capping materials (zeolite, AC/zeolite, AC/sand, zeolite/sand). Pore water concentrations in the different sites were studied using diffusive gradient in thin film (DGT) probes. All capping amendments showed reduction in the pore water concentration of the different heavy metals with top 5 cm showing %reduction greater than 90% for some heavy metals. The relative maxima for the different metals were found to be translated to lower depths with addition of the caps. For two-layered cap with AC, order of placement should be considered since AC can easily be displaced due to its relatively low density. Investigation of methylmercury (MeHg) in the site showed that MeHg and %MeHg in pore water corresponds well with maxima for sulfide, Fe and Mn suggesting mercury methylation as probably coupled with sulfate, Fe and Mn reduction in sediments. Our results showed that thin-layer capping of active sorbents AC and zeolite, in combination with passive sand caps, are potential remediation strategy for sediments contaminated with heavy metals.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.155-163
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• 2014

BACKGROUND: Recent studies for heavy metal stabilization in soil were mainly focused on finding out new materials and its efficiency. But, such a stabilization method can cause disturbance to soil, leading improper environment for agriculture. The object of this study was to demonstrate the effect of the incorporation of green manure crops on heavy metal-contaminated soil. METHODS AND RESULTS: Soil contaminated with heavy metals was collected from the agricultural soils affected by the abandoned mine. Lime stone was selected and treated to contaminated soil. Three kinds of legume green manure crops; Alfalfa (Medicago sativa), Hairy vetch (Vicia villosa), Red clover (Trifolium pratense) were subsequently cultivated in greenhouse condition. It was found that lime stone increased soil pH and decreased the amount of heavy metal absorption by green manure. The application of green manure residues on soil increased soil pH and inorganic nitrogen. CONCLUSION: The C/N ratio of three green manures was low, indicating fast decomposition rate, resulting in nitrogen supplement, consequently. Considering the point that the soil was used for agricultural purpose, it was recommended that hairy vetch and red clover were preferred. Nevertheless, the heavy metal availability was also increased. Thus, it seemed that further study was needed to confirm that how long maintain a phenomenon.

• Journal of Energy Engineering
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• v.6 no.1
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• pp.41-51
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• 1997

A dynamic mathematical model of a thermal power plant with a single drum-type boiler is described with the base on modular concept. The present process model, which is including full scope of the components and high load changes, is based on physical approach through lumped parameters. The module, which means a component of the power plant and must essentially depict the characteristics of the component well, might be interconnected using pressure nodal method in a arrangement determined by users. With the results of the load changes of 75 MW to 95 MW and 95MW to 75 MW with the rate of 3 MW/min, the applicability of the process model is examined connecting to DCS(Dispersion Control System), which has a real running logic of 100 MW real power plant.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.278-284
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• 2015

In general, plant roots accumulate more heavy metals than the above ground organs such as leaf, stem, and fruit. This implies that root medicinal plants would be an issue with excessive heavy metal accumulation. Therefore, the current study was carried out to investigate the distribution of heavy metal (focused on Cd and Pb) concentrations in soils and medicinal plant roots grown in different region of Korea. Total 293 samples for each soil and plant were collected along the national wide. Soil pH, total and phytoavailable metal concentrations (1 M $NH_4NO_3$ extracted) in soils were determined and heavy metal concentrations in root of the medicinal plants were analyzed. Heavy metal concentrations of the soil samples studied were not exceeded standard limits legislated in 'Soil Environmental Conservation Act', except 2 samples for Cu. However, substantial amount of Cd was accumulated in medicinal plant roots with 29% samples exceeding the standard limit legislated in 'Pharmaceutical Affairs Act' while all plant samples were lower than the standard limit value for Pb. Also the current study demonstrated that cadmium concentrations in the roots were governed by the phytoavailable Cd in soils, which decreased as soil pH increased. From this result, application of heavy metal immobilization technique using a pH change-induced immobilizing agents can be suggested for safer root medicinal plant production.