• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.359-368
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• 2014

Photocatalytic cement has been receiving attention due to its high oxidation power that reduces nitrogen oxide, thus contributing to a clean atmospheric environment. However, there has not yet been a thorough investigation on the effect of photocatalytic reactions on the durability of cementitious material, the parent material. In this study, photocatalytic cement samples were exposed to nitric oxide gas and UV along with cycles of wetting and drying to simulate environmental conditions. The surface of samples was characterized mechanically, chemically, and visually during the cycling. The results indicate that that the photocatalytic efficiency decreased with continued NO oxidation. The pits found from SEM indicated that chemical deterioration, such as acid attack or leaching, did occur. However, this was not confirmed by X-ray diffraction. The hardness was not affected, probably due to the formation of CSH as evidenced by the XRD pattern. In conclusion, it was found that photocatalysis could alter cementitious materials both chemically and mechanically, which could further affect long-term durability.

• Korean Journal of Environmental Agriculture
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• v.16 no.1
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• pp.80-93
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• 1997

Pesticide residues in soil could be affected to the growth of micro organisms and the activity of enzymes directly, and successively to the soil properties as pH, Eh and nitrogen metabolism. However, residues are diminished by degradation of soil microorganisms, run-off, leaching, volatilization, photodecomposition and uptake through crops. In this paper research results published in Korea were summarized about translocation of soil residues into crops, fates of residues in soil, effects to the activity of soil microorganisms and metabolic pathways of some pesticides. Generally speaking, pesticide residues in soil were not much affected to the agro-ecosystem except few chemicals. So it should be needed more further researches in this field, continuously.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.10a
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• pp.65-68
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• 1999

A plasma melting system to vitrify ny ash from MSW(Municipal Solid Waste) incinerator has been operated in SHI(Samsung Heavy Industries) since 1996. Waste feeding rate was 200kg/hr. with maximum working power of 500㎾. Because of high melting temperature of fly ash, bottom ash was used as an additive to decrease melting temperature. Data analysis for discharged slag shows volume reduction up to 30% and no leaching of heavy metals such as Pb, Cd, Cr which were an obstacle for landfill and recycle. Atmospheric pollution gas like nitrogen oxides, carbon monoxide, and PCDD/PCDF were restrained below the regulatory limit.

• Carbon letters
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• v.8 no.1
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• pp.17-24
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• 2007

Microporous carbons with narrow pore size distribution have been successfully synthesized by using hydrolyzed and calcined silica as templates and phenol formaldehyde (pf) resin as carbon precursor. Phenol formaldehyde-silica micro composites were prepared by solution route. Subsesequently, silica templates were removed by HF leaching. Resulting carbons were steam activated. The porous carbons were characterized by nitrogen adsorption-desorption isotherm, SEM, FTIR analysis, iodine adsorption, thermogravimetry analysis, etc. Adsorption isotherms show that the porous carbon prepared from calcined silica as templates are microporous with 88% pores of size <2 nm porosity and are of type I isotherm, while porous carbon prepared by using hydrolyzed silica are microporous with 89% microporosity, shows hysteresis loop at high relative pressure indicating the presence of some mesoporosity in samples. The microporosity in porous carbon materials has a bearing on the nature of silica templates used for pore formation.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.803-806
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• 2008

LEACHN is the computer simulation model which can be used to simulate field-scale N transformations and movement and has three organic pools (plant residue, manure, and soil humus), three inorganic pools (urea, nitrate and ammonium) and plant. Pot experiment operated May to October in 2004. LEACHN simulated the nitrogen movement and transformation in soil using method of PEST and trial and error.

• Korean Journal of Organic Agriculture
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• v.10 no.2
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• pp.1-28
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• 2002

Regarding the dangers to soil, water and air, which come from current agricultural application measures for nitrogen, a sectoral approach for a non-polluting liquid manure utilization cannot be used any longer. Slurry was not any longer considered as a tiresome waste produced of animal husbandry, but as a valuable fertilizer. The goal of the largest possible utilization of slurry on the farm was and still is in the foreground, An Integrated system approach has to be found. leading to a drastic improvement of nutrient utilization and hence to a considerably reduced nutrient use. This can only be expected, if the organic manure can be applicated at times, when losses through leaching and volatilization can be minimized. The necessary investments for such concepts can clearly be reduced through cooperation.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.135-144
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• 1995

Understanding on nutrient solute movement during the course of freezing and thawing was attempted through laboratory and field obsevations. Small sectioned tubes with 5cm inner diameter, 0.2cm thick and 1cm long were connected to 30cm long soil columns for laboratory study. The columns were filled with soil, and treated with 20mmol/kg $KNO_3$ for upper 5cm. The upper end was set in the freezing section, and the lower end was set in the refrigerating section of a refrigerator. Temperature was controlled at $-7({\pm}1)^{\circ}C$ and $1.5({\pm}1)^{\circ}C$, respectively. After top 5cm soil was frozen, the columns were sectioned, and analyzed for $NO_3^-$, $NH_4^+$ and $K^+$. For field study, the 20cm inner diameter and lm long soil columns were installed in Chuncheon and Daegwanryung, where the altitude was 74m and 840m, respectively. The soils used were silt loam and clay loam. The top 20cm soils were treated with 50mmol/kg as $KNO_3$. The soil columns were taken during winter freezing and after thawing. By laboratiry study, upward movement of $NO_3^-$ and $K^+$ during the course of freezing was confirmed. The upward movement of $K^+$ was, however, one fifth to one tenth of $NO_3^-$. The upward movement of inorganic nitrogen as well as laboratory during the course of freezing, but large amount of nitrogen was lost from the profile after thawing in early spring. Leached nitrogen from the upper 20cm to lower part was 17 to 24 percents. The maximum depth of leaching during the experiment was 50cm for all soils. The net loss of inorganic nitrogen from the whole profile ranged 8.7 to 39.5 percents. The net loss was greater in Daegwanryung where temperature was lower and snowfall was larger than Chuncheon, and the loss was greater from the silt loam soil than clay loam soil of which percolation rate was small. The results implied that reasons for nitrogen loss during the winter might include surface washing by snow melt as well as leaching and denitrification.

• Journal of Life Science
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• v.12 no.2
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• pp.129-135
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• 2002

Several kinds of thermophilic, aerobic microorganisms (Bacillus genus), metal leaching microorganisms (Thiobacillus, T. ferooxidans), and other nondegradable chemical-degrading microorganisms (Pseudomonas genus) were utilized to study the effect on composting livestock manure. Under the Carbon-Nitrogen ratio (C/N) of 35∼40 and water content of 50∼65% conditions, the composting in the cycling drum reactor showed slower composting and lower temperature increase than that of the manual reactor. Element analysis after composting indicated relatively high levels of mineral contents with the substitutional effect of chemical fertilizer. Metal analysis before and after composting showed lower As in all, Cr in pig, Pb in cow, Hg in chicken, and Cu in cow manure compost than the regulation values. Compost maturity was ascertained by the several maturity tests. Salmonella and E. cozi detection test by SS or EMB agar plate confirmed the safety from the pathogenic microorganisms. The results suggest that the inoculation of metal and some other chemical degrading microorganisms during composting might decrease metal contamination and increase composting rate.

• Korean Journal of Agricultural Science
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• v.19 no.2
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• pp.187-193
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• 1992

The effects of continuous restoration of sludge into the reclamating paddy soil and leaching test of sludge components by soil column were investigated. 1. The contents of nitrogen, phosphorus, potassium, C.E.C. and organic matter(O.M.) were increased in/on the paddy soil treated with paper mill sludge than non-treated. 2. Humic layer depth recognized by color showed the non-treated(10 cm), second year(15 cm) and third year(20 cm), respectively. 3. The effects of sludge treatment showed in the contents of O.M. such as non-treatment(0.9 %) < second year(1.39 %) < third year(1.75 %) in 10 cm depth. 4. All components in soil tested with column were increased by holding capacity of sludge, and the contamination effects of soil and ground water were not found by leaching test.

• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.44-51
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• 2023

Nitrogen fertilizer is an essential macronutrient that requires repeated input for crop cultivation. Excessive use of nitrogen fertilizers can adversely affect the environment by discharging NH₃, NO, and N₂O into the air and leaching into surrounding water systems through rainfall runoff. Therefore, it is necessary to develop a technology that reduces the amount of nitrogen fertilizer used without compromising crop yields. Fertilizer deep placement could be a technology employed to increase the efficiency of nitrogen fertilizer use. In this study, a deep fertilization device that can be coupled to a tractor and used to inject fertilizer into the soil was developed. The deep fertilization device consisted of a tractor attachment part, fertilizer amount control and supply part, and an underground fertilizer input part. The fertilization depth was designed to be adjustable from the soil surface down to a depth of 40 cm in the soil. This device injected fertilizer at a speed of 2,000 m²/hr to a depth of 25 to 30 cm through an underground fertilizer injection pipe while being attached to and towed by a 62-horsepower agricultural tractor. Furthermore, it had no difficulty in employing various fertilizers currently utilized in agricultural fields, and it operated well. It could also perform fertilization and plowing work, thereby further simplifying agricultural labor. In this study, a newly developed device was used to investigate the effects of deep fertilizer placement (FDP) compared to those with urea surface broadcasting, in terms of rice and soybean grain yields. FDP increased the number of rice grains, resulting in an average improvement of 9% in rice yields across three regions. It also increased the number of soybean pods, resulting in an average increase of 23% in soybean yields across the three regions. The results of this study suggest that the newly developed deep fertilization device can efficiently and rapidly inject fertilizer into the soil at depths of 25 to 30 cm. This fertilizer deep placement strategy will be an effective fertilizer application method used to increase rice and soybean yields, in addition to reducing nitrogen fertilizer use, under conventional rice and soybean cultivation conditions.