• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.14-21
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• 1993

N-Heterocyclic aromatics (NHA) are widely occurring environmental pollutants formed during the pyrolysis of nitrogen-containing organic chemicals. NAH are found in significant amounts in tobacco condensates, synthetic fuels, polluted river sediment, and effluents from the heating of coal. Following topical application 7H-dibenzo[c, g]carbazole (DBC) induces cancer in liver as well as skin, indicating that dermal exposure can lead to systemic effect. DBC and dibenz[a,j]acridine (DBA) are examples of NHA. The potency of many carcinogenic compounds is related, at least in part, to the efficiency of their biological activation. We undertook studies to determine which initial metabolites lead to the formation of high levels of carcinogen-DNA adducts in vivo. DBC and DBA's, DBA, trans-DBA-1,2-dihydrodiol (DBA-1,2-DHD), trans-DBA-3,4-dihydrodiol (DBA-3,4-DHD), and trans-DBA-5,6-dihydrodiol (DBA-5,6-DHD), were applied to the skin of mice. There were six adducts that were related to DBC application. These addusts were seen in the target organ, liver at high levels, but at very low levels in non-target organs, skin, lung and kidney. In skin, DBA produced two distinct adducts. The same two adducts were seen when DBA-3,4-DHD was applied. In addition the total adduct level elicited by DBA-3,4-DHD higher than that of parent compound. Two adducts were seen when DBA-5,6-DHD was applied, but these were very different from adducts seen with DBA. These results suggested that activation of DBA to DNA-binding compounds in skin includes initial formation of DBA-3,4-DHD.

• Analytical Science and Technology
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• v.27 no.2
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• pp.108-113
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• 2014

The harmful materials as volatile organic compounds (VOCS) that is easy for gas to be changed from liquid on ambient temperature, those should be controlled by Korea Chemicals Management Association. The VOCs samples should be collected directly in place so that those could be analyzed. Generally but it couldn't avoid to have the risk of analyst. Moreover, if there is the place limited to entrance, it is impossible to collect directly and measure. Owing to such problem, it tried to be solved by open path FT-IR spectrometer that could be studied on the combustion gases within long path and VOCs samples were tried to measure to large volume by remote and real time. Firstly, it was to investigate optimized measured length between the system and benzene sample of VOCs. As result, The optimized measured length was confirmed with 15 meter length and the qualitative analysis could be measured on seven VOC samples. The calibration curve as quantitative analysis of benzene samples could be worked. On the basis of the result, the system as remote monitor could show to have potentiality.

• Korean Journal of Weed Science
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• v.2 no.2
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• pp.114-121
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• 1982

Sagittaria pygmaea Miquel is widely infested and is the most dominant perennial weed in paddy field in Korea. This study was carried out in order to clarify the factors influencing tuber production and the competition ecology. The tuberization capacity in the paddy field transplanted with the small seedlings of rice was higher than in the paddy field transplanted with the vigor seedlings of rice. The stage which rice plants were most damaged by S. pygmaea plants was the period from 31 to 37 days after transplanting. According to the increasing of Eleocharis acicularis Roem. in the condition of rice cultivation, the number of S. pygmaea plants was remarkably reduced. Small size tubers planted within deep soil produced less tubers than large size tubers did. The number of plants and tubers were remarkably increased under the high levels of fertilization. Phosphorus was essential as well as nitrogen for tuberization. And the tuberization capapcity was different with the organic matter content in soil and with the soil moisture.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.227-238
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• 2016

This review article highlights different types of nano-sized catalysts for the selective alcohol oxidation to form aldehydes (or ketones) with supported or immobilized metal nanoparticles. Metal nanoparticle catalysts are obtained through dispersing metal nanoparticles over a solid support with a large surface area. The nanocatalysts have wide technological applications to industrial and academic fields such as organic synthesis, fuel cells, biodiesel production, oil cracking, energy conversion and storage, medicine, water treatment, solid rocket propellants, chemicals and dyes. One of main reactions for the nanocatalyst is an aerobic oxidation of alcohols to produce important intermediates for various applications. The oxidation of alcohols by supported nanocatalysts including gold, palladium, ruthenium, and vanadium is very economical, green and environmentally benign reaction leading to decrease byproducts and reduce the cost of reagents as opposed to stoichiometric reactions. In addition, the room temperature alcohol oxidation using nanocatalysts is introduced.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.3
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• pp.61-66
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• 2018

This research scrutinizes the self-annealing characteristics of copper used to metal interconnection for application of DRAM fabrication process. As the time goes after the copper deposited, the grain of copper is growing. It is called self-annealing. We use the electroplating method for copper deposition and estimate two kinds of electroplating chemicals having different organic additives. As the time of self-annealing is elapsed, sheet resistance decreases with logarithmic dependence of time and is finally saturated. The improvement of sheet resistance is approximately 20%. The saturation time of experimental sample is shorter than that of reference sample. We can find that self-annealing is highly efficient in grain growth of copper through the measurement of TEM analysis. The structure of copper grain is similar to the bamboo type useful for current flow. The results of thermal excursion characteristics show that the reliability of self-annealed sample is better than that of sample annealed at higher temperature. The self-annealed sample is not contained in hillock. The self-annealed samples grow until $2{\mu}m$ and develop in [100] direction more favorable for reliability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.4
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• pp.437-443
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• 1995

Concerns on use of excess amount of chemical fertilizier and pesticide in current farming system turns both of the producer and consumer of agricultural products to an organic farming which use a less chemicals and more natural manure. Rice-duck farming system is one of the strategy to meet the purpose and this experiment was carried out to find the effect of the rice-duck farming system on the quality and yields of rice. 20day-old rice seedling were mechanically transplanted in sandy-loam paddy field and 21 day-old ducks were raised from 3 weeks after transplanting with population of 30 heads per 10a. The plots were consists of reduce fertilizer(70%) with and without duck-raising. The conventional fertilizer treatment without duck-raising was used as check. The results obtained are summarized as follows. The weeds population of test plots which were raised with duck for 3 consecutive years was less than that of test plots without duck-raising, though a speciffic population of Echinochola crusgallis were increased. The weed control effect was higer in duck-raising than in check at the maximum tillering stage but, not at later stages of rice plant. It was found that the small animals and insects inhibiting in the rice field were reduced by duck-treatment, however, there were also damages of grass leaf roller at booting stage in the plots of duck-raising. In rice-duck plot, dark green leaf color were found: 41.8 of SPAD value than 38.6 of SPAD in check plot. Higher root activity and surface soil oxidation were also observed in rice-duck plot than check plot. 3% of the increase in yield was observed by duck-treatment. However, the expected increase of the palatability wsa not observed. This may be due to the unfavorable weather conditions during the rice growing in this expriment.

• Journal of Korean Society on Water Environment
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• v.32 no.4
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• pp.357-366
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• 2016

N-nitrosamines are a class of carcinogenic chemicals that can pose significant hazards to the human life. Ultraviolet (UV) light irradiation is considered as one of the effective methods to reduce N-nitrosamines in the aqueous phase. This study aimed to investigate the pH influence on UV photodegradation of N-nitrosamines (i.e., N-nitrosodibutylamine (NDBA) and N-nitrosopyrrolidine (NPYR)) closely related to water treatment. Photodegradation rate constants of NDBA and NPYR remained between 3.26×10^-2 L/W-min to 5.08×10^-3 L/W-min and 1.14×10^-2 L/W-min to 2.80×10^-3 L/W-min at pH2-10, respectively. This study also focused on the formation of oxidized products (i.e., primarily NO^2- and NO^3-). Under slightly acidic and neutral conditions, NO^2- formation was more prevalent than NO^3- formation, while under strong acidic conditions, NO^3- was more prevalent. There was no significant change in total organic carbon (TOC) and total nitrogen (TN), suggesting negligible loss of N-nitrosamines and degradation products from the system. NDBA was easily photodegraded than NPYR. This study also demonstrated that a lower pH is a favorable condition for photolytic degradation of N-nitrosamines in water.

• Korean Journal of Community Nutrition
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• v.16 no.4
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• pp.466-472
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• 2011

Hazardous chemicals, such as polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs) and heavy metals, are known as being harmful to human health were included in oils released by the Herbei Spirit Oil Spill accident in December 2007. To investigate changes of eating habits by the exposure to harmful substances, we conducted 5 focus group interviews for residents at Taean coast areas, who had experienced the oil spill accident. Participants included 46 women (mean age: $57.2{\pm}10.9$) who were mainly responsible for preparing family meals. Focus group discussions were audio-taped, transcribed and categorized by themes. Participants expressed more frequent illness symptoms such as dizziness, vomiting, visual loss, and skin diseases after the accident. They mentioned that their worries about economic hardship and worsened health status since the accident induced mental problems, such as depression about their children. Regarding eating habits, participants reported less intakes of fishes and meats and relatively more intakes of vegetables and kimchi due to the lack of household incomes after the accident. Although the participants had been used to collecting or catching fish or shellfish for their consumption previously, they mainly purchased these foods from local markets after the accident. Changes of eating habits induced by the accident included drinking boiled water and having steamed or fried seafood rather than raw seafood. Changes of food intakes occurred less frequently in older adults due to their longterm fixed eating habits, although they felt uncomfortable for having raw fish. The findings of this study clearly present that the exposure of hazardous substances by the oil spill accident had a significant impact on changes in eating habits besides economic, physical, and mental problems among the residents in Taean. Continuous health and nutrition monitoring and support are needed.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.781-790
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• 2014

Contaminants such as organic matters, nutrients and toxic chemicals in rivers and lakes with a weak flow rate are first removed from the water and accumulated in the sediments. Subsequently, they are released into the water column again, posing direct/indirect adverse effects on the water quality and aquatic ecosystems. In particular, phosphorus is known to accelerate the eutrophication phenomenon when it is released into the water column via physical disturbance and biological/chemical actions as one of important materials that determine the primary production of aquatic ecosystems and an element that is stored mainly in the sediments in the process of material circulation in the body of water. In this study, the effect on reducing phosphorus release in sediments was analyzed by applying different capping materials to lake water, where the effect of aquatic microorganisms is taken into account, and to distilled water, where the effect of microorganisms is excluded. The experimental results showed that capping with chemical materials such as Fe-gypsum and $SiO_2$-gypsum further reduced the phosphorus release by at least 40% compared to the control case. Composite materials like granule gypsum+Sand showed over 50% phosphorus release reduction effect. Therefore, it is determined that capping with chemical materials such as granule-gypsum and eco-friendly materials such as sand is effective in reducing phosphorus release. The changes in phosphorus properties in the sediments before and after capping treatment showed that gypsum input helped to change the phosphorus that is present in lake sediments into apatite-P, a stable form that makes phosphorus release difficult. Based on the above results, it is expected that the application of capping technology will contribute to improving the efficiency of reducing phosphorus release that occurs in river and lake sediments.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.390-397
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• 2010

Residual solvents in foods are defined as organic volatile chemicals used or produced in manufacturing of extracts or additives, or functional foods. The solvents are not completely eliminated by practical manufacturing techniques and they also may become contaminated by solvents from packing, transportation or storage in warehouses. Because residual solvents have no nutritional value but may be hazardous to human health, there is a need to remove them from the final products or reduce their amounts to below acceptable levels. The purpose of this study was to develop and evaluate an analytical method for the screening of residual solvents in health functional foods. Furthermore, the aim of this study was to constitute a reasonable management system based on the current state of the market and case studies of foreign countries. Eleven volatile solvents such as MeOH, EtOH, trichloroethylene and hexane were separated depending on their column properties, temp. and time using Gas Chromatography (GC). After determining the GC conditions, a sample preparation method using HSS (Head Space Sampling) was developed. From the results, a method for analyzing residual solvents in health functional foods was developed considering matrix effect and interference from the sample obtained from the solution of solvents-free health functional foods spiked with 11 standards solutions. Validation test using the developed GC/HSS/MS (Mass Spectrometry) method was followed by tests for precision, accuracy, recovery, linearity and adequate sensitivity. Finally, examination of 104 samples grouped in suits was performed by the developed HSS/GC/MS for screening the solvents. The 11 solvents were isolated from health functional foods based on vapor pressure difference, and followed by separation within 15 minutes in a single run. The limt of detection (LOD), limit of quantification (LOQ), recovery and coefficient of variation (C.V.) of these compounds determined by the HSS/GC/MS were found to be 0.1 pg/mL, 0.1-125 pg/g, 51.0-104.6%, and less than 15%, respectively. Using the developed HSS/GC/MS method, residual solvent from 16 out of 104 health functional products were detected as a EtOH. This method therefore seems t o be a valuable extension ofanalytical method for the identification of residual solvents in health functional food.