• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1073-1078
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• 1999

The objectives of this study are to examine the applicability of waste slurry from soda ash manufacturing industries as a coagulant for the treatment of wastewater containing fine silica particles, and to reduce the cost of wastewater treatment containing silica. Acceptable water quality can be obtained with a little dosing of waste slurry by gelation before the coagulation process so it could be concluded that the waste slurry from soda ash can be used as a coagulant. Based on the results of experiments, the optimum pH of gelation for silica in wastewater was around five and the treatment process with the gelation of silica could reduce the chemical dosage and waste sludge after coagulation. Dewatering and settling characteristics of the floc after coagulation with the waste slurry are better than those of the floc after coagulation with the lime milk only.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.6
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• pp.1034-1040
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• 1998

The nutritional quality and physiological activity of cultivated hoelen from 13 months to 24 months were examined to compare with natural hoelen. General compositions of hoelen were as follows re spectively; crude protein 1.80~2.50%, crude fat 0.68~1.23%, crude ash 0.12~0.43%, crude fiber 6.30~7.14%, nitrogen free extract 89.25~90.44%. The major free sugar was glucose, and the content of 13 months cultivated hoelen was higher than any other cultivated hoelen. The major fatty acids of hoelen were linoleic acid, palmitic acid, stearic acid and oleic acid. The ratio of unsaturated fatty acids was 62.62~77.96% and the content was higher in cultivated hoelen than in natural hoelen. The contents of amino acid were high in the order of tyrosine, aspartic acid, glutamic acid and serine, and increased as the day of cultivation became longer. The contents of mineral components were higher in the order of Ca, K, Mg and the contents of Na and Ca were higher in natural hoelen than in cultivated hoelen. The contents of pachymic acid and dehydropachymic acid was similar in the natural and cultivated hoelen. On the results of antimicrobial test the ethanol extract showed a stronger effect than water extract, and had an excellent antimicrobial activity on Micrococcus luteus and Escherichia coli. The ethanol extract of hoelen showed comparatively strong electron donating ability. The ethanol extract of hoelen showed a high inhibition activity on the growth of lung cancer, ovary cancer, skin cancer, central nerve cancer and rectum cancer, especially the activity of 19 months cultivated hoelen was the highest. On the above results of nutritional quality and physiological activity of hoelen, it is supposed that the picking date of cultivated hoelen was suitable over than 19 months.

• Journal of Food Hygiene and Safety
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• v.10 no.2
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• pp.111-131
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• 1995

Quality changes of sausages in refrierated storage for 60 days were investigated. Nine types of sausages produced in Korea were stored at 4$^{\circ}C$(3~5$^{\circ}C$), and then chemical, microbiological, and sensory characteristics were evaluated on every 10 days. The proximate analysis showed considerable variation in fat (23.97%, 17.10~30.20%) with less variation in moisture (51.96%, 48.10~56.30%) and protein (12.96%, 11.40~13.95%), pH value decreased over time averaging from 6.31 to 6.22 with no significant difference. Water activity was consistent over refrigerated storage averaging 0.95. Volatile basic nitrogen (VBN) values were still within 20 mg% though VBN for all types significantly increased over time (p<0.05). Thiobarbituric acid (TBA) values were well below 1.0 though TBA showed significant differences among storage periods (p<0.05). Standard plate counts (SPCs) significantly increased during storage (p<0.05) while coliform group was not counted in all cases. SPCs reached 104 CFU/g in two types after 50 days' storage and were below 105 CFU/g in all types after 60 days' storage. Instrumental texture analysis showed that springiness, adhesiveness, and hardness signficantly decreased over time (p<0.05) while no change was observed in external color. significantly decreased over time the 60-day storage period (p<0.05) while cohesiveness, chewiness and gumminess did not change. Lightness, redness and yellowness of the internal Hunter color significantly decreased over time (p<0.05) while no change was observed in external color. Sensory profile showed that flavor, taste, texture and overall acceptable after 60 days' storage at 4$^{\circ}C$. However, the shelf-life of the samples should be decided in the consideration of the growth rate other spoilage flora coupled with the bacterial growth after 50 days' storage.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.33-51
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• 2013

Spatial and temporal characteristics of nitrate contamination and hydrogeochemical parameters were investigated for springs and surficial and bedrock groundwaters in northeastern part of Hongseong. Two field investigations were conducted at dry and wet seasons in 2011 for 120 sites including measurement of field parameters with chemical analyses of major dissolved constituents. Nitrate concentrations were at background levels in springs while 45% of bedrock groundwater and 49% of surficial groundwater exceeded the drinking water standard of nitrate (10 mg/L as $NO_3$-N). The difference in nitrate concentrations between surficial and bedrock groundwater was statistically insignificant. Cumulative frequency distribution of nitrate concentrations revealed two inflection points of 2 and 16 mg/L as $NO_3$-N. Correlation analysis of hydrogeochemical parameters showed that nitrate had higher correlations with Sr, Mg, Cl, Na, and Ca, in surficial groundwater in both dry and wet season. In contrast, nitrate had much weaker correlations with other hydrogeochemical parameters in bedrock groundwater compared to surficial groundwater and had significant correlations only in wet season. Temporally, nitrate and chloride concentrations decreased and dissolved oxygen (DO) increased from dry season to wet season, which indicates that increased recharge during the wet season affected groundwater quality. Aerobic conditions were predominant for both surficial and bedrock groundwater indicating low natural attenuation potential of nitrate in the aquifers of the study area.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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• pp.66-74
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• 2015

DIP(deinked pulp) was bleached by FAS, $Na_2S_2O_4$ and $H_2O_2$, which are widely used in DIP bleaching process, in order to improve optical properties of DIP, and the bleaching efficiencies of DIP and environmental loads of waste water were compared, depending on bleaching chemical dosages. With the application of different bleaching chemicals, some positive improvements were shown in optical and physical properties of bleached pulp. However, the physical properties of bleached DIP and their characteristics of wastewater were remarkably different, depending on dosages and bleaching reagents. DIP chemicals with FAS and $Na_2S_2O_4$ have higher improvement in optical and physical properties than $H_2O_2$. Also, environmental loads such as pH, turbidity, SCODcr and cationic demand were decreased in reductive bleaching process. Despite of higher effectiveness of reductive bleaching process, there were some environmental problems caused by sulfur ions from FAS and $Na_2S_2O_4$. With the method of sulfur ion controls, it would be more effective than $H_2O_2$ bleaching process.

• Journal of Environmental Science International
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• v.27 no.8
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• pp.641-650
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• 2018

Paddy-upland rotation system is one of the important cropping system for improving soil quality and crop productivity. we conducted to investigate the effect of paddy-upland rotation system on soil properties and crop productivity in reclaimed tidal land. The paddy-upland rotation could be effective to conserve soil water contents and prevent from salt damage when cultivating upland crops. The first two years of maize cultivation after rice cultivation could be effective to secure stable production. However, in case of soybean crop, the rotation effect might be lower than that of maize. In the first year, the yield of soybean was 214 kg/10a. In the second and third year, the yields of soybean decreased consecutively to 152, 123 kg/10a respectively. In this paper, it would be suggested that maize be cultivated for up to two years and soybean be cultivated for one year after rice crop grown in reclaimed tidal land. This study could be provide basic data of the physico-chemical properties applicable to paddy-upland rotation system at reclaimed tidal lands.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1028-1032
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• 2009

In this study, the influences of silicon-based gas barrier films fabricated by using a facing target sputtering(FTS) system on the gas permeability for flexible displays have been investigated. Under these optimum conditions on the $SiO_x$ film with oxygen concentration($O_2/Ar+O_2$) of 3.3% and the $SiO_xN_y$ film with nitrogen concentration($N_2/Ar+O_2+N_2$) of 30% deposited by the FTS system, it was found that the films were grown about 4 times higher deposition rate than that of the conventional sputtering system and showed high transmittance about 85% in the visible light range. Particularly, the polyethylene naphthalate(PEN) substrates with the $SiO_x$ and/or $SiO_xN_y$ films showed the enhanced properties of decreased water vapor transmission rate (WVTR) over $10^{-1}\;g/m^2{\cdot}day$ compared with the PEN substrate without any gas barrier films, which was due to high packing density in the Si-based films with high plasma density by FTS process and/or the denser chemical structure of Si-N bond in the $SiO_xN_y$ film.

• The Korean Journal of Community Living Science
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• v.16 no.3
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• pp.87-96
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• 2005

This survey was conducted to assess the perception of hazards and washing behavior of vegetables of 500 housewives in Korea. The subjects were selected by the stratified random sampling method. The survey was performed using a structured questionnaire through telephone interviews by skilled interviewers. Most people have bought vegetables and fruits in the supermarket or (traditional) markets rather than stores, department stores, or direct transactions. Eighteen percent of the subjects felt vegetables were secure and were not concerned about safety. But $42.8{\%}$ were concerned about vegetable safety. The perceptions of vegetable-related hazards differed significantly by the respondent's socioeconomic characteristics. Higher concern about vegetable safety was reported by subjects with higher income, children, and who usually buy vegetables in supermarkets or department stores. Most subjects ($88.6{\%}$) perceived that residues of chemical substances such as pesticides were the most significant potential vegetable risk factor, followed by heavy metal, and pathogens. Housewives mainly rinsed vegetables in flowing-water ($85.2{\%}$ of subjects), 3${\~}$4 times ($63.8{\%}$ of subjects), and without detergent ($90.6{\%}$). Subjects believed that hazards decreased by blanching or boiling vegetables rather than washing. Subjects realized more or less correctly the removal rate of pesticide and pathogen through the washing and cooking processes. However, the removal rate of heavy metals was less than subjects thought it would be. Therefore, the scientifically assessed results on safety in the washing and cooking process should be opened to the public to provide the right-to-know and assure confidence in consumers.

• Korean Journal of Organic Agriculture
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• v.8 no.1
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• pp.111-129
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• 1999

In order to get some basic data to check the environmental sound function against soil and water pollution and the safe vegetable production by korean organic farming where an internationally recognized basic concepts of soil fertility management for organic farming is not practiced and only applying the organic fertilizer to maintain the soil fertility, the chemical characteristics of soils and $NO_{3}^{-}$ content of chinese cabbage and lettuce cultivated by the conventional farming, greenhouse cultivation and organic farming were investigated. The highest value of $NO_{3}^{-}$-N in 0~30cm subsoil among the three different farming systems was found in the subsoil of organic farming and it was 3.6 and 6.6 times higher than those of conventional farming in chinese cabbage and lettuce respectively. $P_2O_5$ accumulation in the rhizosphere by organic farming also showed the highest value. The accumulation of $NO_{3}^{-}$-N and $P_2O_5$ in organic farming soil were similar or even more higher to those of greenhouse cultivation. The $NO_{3}^{-}$ accumulation in the vegetable by organic farming reached 3224ppm for chinese cabbage and 2543ppm for lettuce, and it were 4.7 and 6.4 times higher than those by conventional farming. It was concluded that there is urgently necessary to introduce the main concepts of soil fertility management of the Basic Standard of IFOAM, EU regulation and FAO/WHO Codex Alimentarius on organic agriculture(draft) into korean organic agriculture for the operation of environmental sound system and the production of sate vegetable in terms of $NO_{3}^{-}$ content.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.146-151
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• 2014

Objectives: Chrysotile is mineralogically distinct from amphiboles, displaying a notably different chemical structure. The thin sheets that form chrysotile fiber lead to the ability of the lung/macrophage system to decompose the chrysotile fibers. This study was performed in order to compare the physicochemical characteristics of Korean asbestos with those of Canadian amphiboles. Materials: An acid solubility test for each test substance was done to compare pH 4.5 and pH 1.2 distilled water. Asbestos fibers which had been placed in acid solutions for five days, five weeks and weeks were analyzed with a transmission electron microscope equipped with an energy dispersive X-ray spectrometer (TEM-EDS). Results: The composition element (Mg) of Korean chrysotile, Korean anthophyllite and Canadian amosite significantly decreased from 5 days and also decreased significantly after 5 weeks and 10 weeks. Only the composition (Mg) of Canadian crocidolite did not change under any conditions. From 5 days, the Mg of Korean chrysotile, Korean anthophyllite and Canadian amosite were significantly lower than before the acid treatment, but there were no changes over time or by the pH of the acid solutions. Particularly after 10 weeks, the composition (Mg) of Korean chrysotile in the pH 1.2 acid solution showed a rapid reduction of 15.86%. Conclusions: Korean chrysotile was very weak in an acid environment, beginning to show significant changes after 5 days. The Mg component rapidly decreased after 10 weeks in the pH 1.2 acid solution.