• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.101-108
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• 2005

Because the stone cultural properties located outdoors, they have been altered and deteriorated in external appearance due to environmental factors such as acid rain, extreme change in temperature, and salts. Damage to stone cultural properties is accelerated particularly due to recent industrial development and environmental pollution. An experimental study was conducted to evaluate the effect of environmental contaminants on the weathering of granite. And as part of the developing of conservation method, $TiO_2$ catalyst was prepared and tested. When fresh granite was dipped into the salt and acid solutions, dissolution rate of eight minerals (Si, Mg, Ca, Na, K, Fe, Mn, Al) are abruptly increased at initial stage of reaction and then increased steadily until 100 cycles. After salt and acid solution experiments, the mineral compositions of the granite surface were lower then that of the fresh granite and density of the weathered granite was steadily decreased from $2.60\;g/cm^3$ to $2.56\;g/cm^3$, but Poissions ratio and absorption ratio were slightly increased. It was expected at stone cultural assets could be weathered by salts and acid rain. In the case of $TiO_2$ was coated to the granite, the dissolution rate of minerals and absorption ratio of $TiO_2$ coated granite were decreased. Therefore, the $TiO_2$ coating method tested in this study considered to be a viable method to assist in the conservation of stone cultural properties from environmental contaminants.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.385-390
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• 2005

In this study, nano sized colloidal Ag was made by using a seed sol method. Colloidal Ag solution was spouted on the surface of the inorganic pigment using the hybridizer system and spray nozzle. Then, the surface of the inorganic pigment was modified by $TiO_2$ to obtain the antibacterial ability. In the manufacturing process of nano sized colloidal Ag, it was confirmed that the size of particles increased by addition of $AgNO_3$ and increased the reaction time. The antibacterial measurement of the inorganic pigment showed that the growth of fungus decreased as the reaction time was increased. After the antibacterial ability appeared, in 5~7 h of the antibacterial inoculation experiment, it was measured that the antibacterial activity was excellent at a fixed time frame. The photodecomposition of benzene using $TiO_2$ as the photocatalyst showed 60~70% efficiency in about 80 min. reaction time. It was shown that more than 90% of this efficiency was achieved in the reaction time of about 30 min.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.311-316
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• 2018

As the lives of people have improved, the demand for improved indoor air quality has increased. Various methods are used to remove biological air pollutants, such as UV/photocatalytic devices and ozone generators. However, these methods have disadvantages such as energy consumption, high corrosivity and toxicity. To overcome these disadvantages, an antibacterial copper filter was fabricated and its antimicrobial activity was then tested against two fungi (P. pinophilum, C. globosum) and one bacteria (S. aureus) Moreover, the ability to remove suspended microorganisms was tested step by step from the chamber stage to the air conditioning system. The results revealed 100% antimicrobial activity after 24 hours for the two fungi, while this value was 99.9% after 18 hours for the bacteria. Moreover, the antibacterial activity was higher when the chamber and air purifier were used than was obtained using a general antibacterial HEPA filter. Also, as a filter for system air conditioner, the antibacterial activity was lowered in offices and hospitals. In conclusion, the copper filter was found to have sufficient antibacterial activity for use as an antibacterial filter; however, further research on its preparation methods and materials is warranted.

• Korean Journal of Environmental Agriculture
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• v.17 no.2
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• pp.107-116
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• 1998

In an effort to reduce artifically the residual pesticides on crop and soil by accelerated photolysis,some 40 among the naturally occurring and synthetic coumpound were screened for photosensitization and/or photocatalysis and six promising chemicals were selected.The fungicides and the four selected photosensitizers and/or photocatalyst (PS) were applied to each crop.The results obtained are summarized as follows. 1. The wavelengths of maximum absortion (${\lambda}$max) and the molar absorptivites (${\varepsilon}$max) of procymidone,vinclozolin,and carbendazim in acentone were all 209 nm and 853,854,and 8740 respectively. 2. Of the 40 naturally-occuring and synthetic compounds screened,six promising ones were selected and designated as PS-1 (aromatic ketone),PS-2(aromatic amine)PS-3(quinone) ,PS-4 (inorganic compound),PS-5(organic acid salt) and PS-6(semiconductor photocatalyst). 3. In the accelerated photolysis of pesticide in soil by applying PS ,procymidone was decoposed rapidly by virtue of PS-2,being 59% of the control 3 days after application. 4. The vinclozolin residue in soil was reduced to 71% and 21% of the control 1 and 15 days,respectively,after PS-2 application. 5. The photolysis of carbendazim in soil was not accelerated by any of the PS tested. 6. The pesticide residues on the crop were prominently reduced by PS application.The procymidone residue on tomato was reduced to 47% of the control 15 days after PS-1 application and that on red pepper reduced to 57% 15 days after PS-2 application. 7. Vincrozolin residus remaining on tomato 1 and 15 days after PS-2 application were 38% and 56% of the control whereas those on the red pepper were 82% and 64%,respectively. 8. PS-2 was the most effective for the accelerated photolysis of carbendazim residues remaining on tomato, whereas on red pepper, the four of PS tested were all effective, but did not make much difference between them. This might be due to the shielding of sunlight by the leaves of red pepper not to exert the photosensitizing effect of PS-2 to the full.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.388-395
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• 2016

This paper explores the photocatalytic sensitivity of cement mortar incorporated with recycled $TiO_2$ from waste water sludge. Basically, $TiO_2$ cluster sank down slowly to the bottom of cement mortar specimen before setting and hardening process. This leads the mismatch of $TiO_2$ concentration on the top and the bottom faces of a specimen. This poorly dispersed $TiO_2$-cement mortar naturally exhibits poor NOx removal efficiency especially on the top of cementitious structure. In architectural engineering application such as building or housing structures, one can simply filp over from the bottom so that more $TiO_2$ concentrated surface can be placed outward into the air. However, in highway pavement case, this could not be applicable due to in-situ installation of concrete pavement. Hence, the dispersion of $TiO_2$ cluster inside the cementitous material is getting important issue onto road construction application. To elaborate this issue, according to our results, silica fume, high-ranged water reducer, viscosity agent, blast furnace slag were not enhanced much of dispersion characteristics of $TiO_2$ cluster. The combination of foaming agent and accelerator of hardening with viscosity agent and small grain size of fine aggregate may help the dispersion of $TiO_2$ inside cementitious materials. Even though the enhanced dispersion were applied to the specimen, NOx removal efficiency doest not change much for the top surface of the specimen. This concurrently affected by the presence of tiny air voids and the dispersion of $TiO_2$ in that these voids could easily adsorbed NOx gas with the aid of large surface area.

• The Korean Journal of Pesticide Science
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• v.3 no.2
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• pp.47-53
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• 1999

Photosensitizing activities of some photosensitizers (PS) for the artificial diminution of pesticide residues on horticultural crops were investigated. Five fungicides, iprodione, bitertanol, chlorothalonil, myclobutanil, and dichlofluanid were sprayed on apple and cucumber, followed by the application of each selected photosensitizer, and the samples were collected 0, 1, 3, 7, 15 days after the photosensitizer application and analyzed for the residual amounts. Of the 40 photosensitizers tested, six selected on the basis of the eliminating effect of pesticide residues were PS-1 (aromatic ketone), PS-2 (aromatic amine), PS-3 (quinone), PS-4 (inorganic compound), PS-5 (organic acid salt), and PS-6 (semiconductor photocatalyst). The residual amount of iprodione after 15 days of the application of PS-1 was 74% of that of the control. For bitertanol, the residual amount after 15 days of the application of PS-1 accounted for 78% of that of the control. The residual amounts of chlorothalonil after 1 day of the application of PS-1 and PS-2 accounted for 56 and 54% of those of the control, respectively. The residual amounts of iprodione on cucumber after 3 days of the application of the photosensitizers PS-1 and PS-2 were 44 and 67% of those of the untreated control, respectively. For myclobutanil, the residual amount after 15 days of the application of PS-6 accounted for 45% of that of the control. In case of dichlofluanid, the residual amount after 3 days of the application of PS-1 accounted for 44% of that of the control. Based on the results, PS-1 turned out to be the most promising photosensitizer for the accelerated photodegradation of the above fungicides on apple and cucumber.