• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.245-250
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• 2004

This study investigated the micropollutants present in raw water supplied for the several drinking water treatment plants in Seoul. The target sample waters were collected from the several sites, such as Jayang (JY), Kuui (KI), Paldang (PD) and Kangbuk (KB) at the Han-River stream. The analytical method used in this study enable us to detect about 300 kinds of chemicals commonly found in surface water at ppt level by GC-ion trap MS. In this study, the consideration on the analytic results focused on the four hazardous organics, such as benzenes, phenols, phthalates and pesticides. The numbers of each detected micropollutant were 1~8 kinds for benzenes, 1~7 kinds for phenols, 5~7 kinds for phthalates and 1~9 kinds for pesticides. For the pesticides, the higher concentration was detected in the water samples collected from PD and KB adjacent to the farming area, and at June and July, which is the busy farming season. The total concentrations of each micropollutants detected at all the sites were significantly lower than those of drinking water regulation in Korea as well as other advanced countries. However, the frequently detected micropollutants requires the steady and precise monitoring for the effective management of drinking water source.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.59-63
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• 1996

The antimicrobial activity of mugwort(artemisia asiatica Nakai) was investigated. The methanol extract or dried mugwort was fractionated to hexane, chloroform, ethylacetate, butanol, and aqueous fractions. The hexane fraction among these fractions showed the hifhest inhibitory effect on the growth of microorganisms such as Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Lactobacillus plantarum. Bacillus subtilis, Escherchia coli, and Staphylococcus aureus were completely inhibited at a concentration of 250, 500 , and 750$\mu\textrm{g}$/ml respectively. The hexane fraction was further fractionated into 16 subfractions by silica gel column and thin layer chromatography(TLC). The subfraction No. 8, 9, and 10 on TLC exhibited high antimicrnial activity. At 3rd fractionation, subfraction No. 2 inhibited the growth of microorganisms at 500$\mu\textrm{g}$/ml. Heptadecane, dodecamethyi cyclohexasiloxane, (E,E)-2,4-decadienal, dodecamethul pentasiloxane, coumarin, 5,6,6,6a-tetrahydro-4,4,7a-trimethyl-2(4H)-benzofuranone, neophytadiene, tridecanoic acid, methyl ester, 2-methyl-4,5-nonadiene, (Z,Z)-9-12-octadecadienoyl chloride, and bis(2-ethylhexyl) were identified from this antimicrobial fraction by GC-MS.

• Advances in environmental research
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• v.9 no.2
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• pp.109-121
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• 2020

Phenol is frequently present as the hazardous pollutant in petrochemical and pesticide industry wastewater. Because of its high toxicity and carcinogenic potential, a proper treatment is needed to reduce the hazards of phenol carrying effluent before being discharged into the environment. Phenol biodegradation with microbial consortium offers a very promising approach now a day's. This study focused on the formulation of phenol degrading bacterial consortium with three bacterial isolates. The bacterial strains Bacillus cereus strain VCRC B540, Bacillus cereus strain BRL02-43 and Oxalobacteraceae strain CC11D were isolated from detergent contaminated soil by soil enrichment technique and was identified by 16s rDNA sequence analysis. Individual cultures were degrade 100 μl phenol in 72 hrs. The formulated bacterial consortium was very effective in degrading 250 μl of phenol at a pH 7 with in 48 hrs. The study further focused on the analysis of the products of biodegradation with Fourier Transform Infrared Spectroscopy (FT/IR) and Gas Chromatography-Mass Spectroscopy (GC-MS). The analysis showed the complete degradation of phenol and the production of Benzene di-carboxylic acid mono (2-ethylhexyl) ester and Ethane 1,2- Diethoxy- as metabolic intermediates. Biodegradation with the aid of microorganisms is a potential approach in terms of cost-effectiveness and elimination of secondary pollutions. The present study established the efficiency of bacterial consortium to degrade phenol. Optimization of biodegradation conditions and construction of a bioreactor can be further exploited for large scale industrial applications.

• Membrane Journal
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• v.15 no.4
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• pp.297-309
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• 2005

As a number of potential endocrine disrupting compounds (EDCs) are released into the environment, recently growing attention has been drawn to them. Therefore sensitive and reliable analytical methods are essential to monitor those compounds. In this study, complementary CC-MS and LC-MS were employed to analyze the endocrine disrupters, and the results of two methods were compared for di(2-ethylhexyl)phthalate (DEHP), benzylbutylphthalate (BBP), pentachlorophenol (PCP), and 4,4'-Isopropylidenediphenol (Bisphenol-A, or BPA). The results indicate that it was possible to lower the detection limits of EDCs by LC-MS. Also, LC-MS enabled to identify the EDCs as almost intact molecules. Furthermore, this study presented a nanofiltration membrane (MWCO 250) and a ultrafiltration membrane (MWCO 1,000) filtration system as methods far removing EDCs from drinking water containing $\gamma$-BHC, p,p'-DDE, BBP, p,p'-DDT, DEHP, PCP, and BPA. Cross-flow type nanofiltrations showed $100\%$ removal of EDCs, and the result implies that MWCO 250 nanofilter was sufficient for treatment of EDCs. The ratio of permeate flux to mass transfer coefficient of nanofiltration, high flux ultrafiltration, and low flux ultrafiltration with ultrapure water were 0.67, 3.4, and 0.44, respectively. It was found that nanofiltration and low flux ultrafiltration were operated at a diffusion dominant condition, and the high flux ultrafiltration was operated at a convection dominant condition. Furthermore, a diffusion dominant process attained reasonable rejection of EDCs. The removal in the ultrafiltration was depending on the molecular weight of an EDC, and the filtration was governed by diffusion-dominant hydrodynamic conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.1
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• pp.46-50
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• 1997

This study was conducted to find out the main soil physical properties to control the soil hardness in tamped condition. Sandy loam soil was taken and fill it up to wood cubes and then differently trampling experimental cubic lots which were mulched with various materials, such as, leaves, wood plates and bricks. Soil physical properties were measured 2" core and samples were taken at 250 sites with soil hardness. There were highly significant positive correlations between soil hardness and bulk density, and between bulk density and water content. Negative correlations were found between soil hardness and water content, and between soil hardness and gravel content. The correlation coefficients were increased by multiple correlation between soil hardness, bulk density, volumetric water and gravel content. Bulk density was the main factor to control the hardness, and volumetric water and gravel contents were less effected to soil hardness.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.3
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• pp.464-470
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• 2001

The purpose of this study was to evaluate the tensile strength of light-cured restorative posterior resin-based composites. Five commercially available light-cured composites(Denfil : DF, P60 : PS, Unifil S : US, Z100 : ZH, Z250 : ZT) were used. Rectangular tension test specimens were fabricated in a teflon mold giving 5mm in gauge length and 2mm in thickness. Specimens were subjected to the 5,000 thermal cycles between $5^{\circ}C$ and $55^{\circ}C$ and the immersion time in each bath was 15 second per cycle. Tensile testing was carried out with Instron at a crosshead speed of 0.5mm/min and fractured surface were observed with scanning electron microscope. The obtained results were summarized as follows; 1. The tensile strength of PS was highest. PS was significantly higher than DF, US and ZH(p<0.05) but in the case of ZT was similar to PS(p>0.05). 2. The tensile strength DF was lowest. DF was significantly lower than PS, US, ZH and ZT(p<0.05). 3. The tensile strength of US and ZH were significantly lower than PS and ZT(p<0.05). but were significantly higher than DF(p<0.05). The tensile strength of US and ZH were similar(p>0.05).

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.284-289
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• 2017

Oxidized polyethylene wax (OPEW) is, one of the food additives, used as a coating agent in citrus fruits and nuts. OPEW is authorized to quantum satis in EU, USA, and is acceptable less than 250 mg/kg in Australia and New Zealand. But OPEW is unauthorized as a food additive in Korea. This study was to establish the analytical method of OPEW and demonstrate the effective application of various food samples. We first conducted to compare the various analytical method including acid value (AV), high temperature gel permeation chromatography (HT-GPC), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS), gas chromatography flame ionization detector (GC-FID) and fourier transform infrared spectroscopy (FT-IR). This result indicated that FT-IR spectrum of OPEW treated food sample displayed absorption bands for carbonyl group (C=O, $1714cm^{-1}$), ester group (C-O, $1463cm^{-1}$), aliphatic group (C-H, $2916cm^{-1}$). Furthermore, IR spectrum of OPEW treated food sample showed similar tendency with IR spectrum of OPEW standard. Therefore, it is confirmed that analytical method using FT-IR can be detected on analysis of OPEW in food. As a result of monitoring of 111 samples using established analytical method, OPEW was not detected in the food samples.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.4
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• pp.459-464
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• 2017

Biphenyl is used as an intermediate in the production of crop protection products, a solvent in pharmaceutical production, and as a component in the preservation of citrus fruits in many countries. Biphenyl is not authorized for use and also does not have standards or specifications as a food additive in Korea. National and imported food products are likely to contain biphenyl. Therefore, control and management of these products is required. In this study, a simple analytical method was developed and validated using HPLC to determine biphenyl in food. These methods are validated by assessing certain performance parameters: linearity, accuracy, precision, recovery, limit of detection (LOD), and limit of quantitation (LOQ). The calibration curve was obtained from 1.0 to $100.0{\mu}g/mL$ with satisfactory relative standard deviations (RSD) of 0.999 in the representative sample (orange). In the measurement of quality control (QC) samples, accuracy was in the range of 95.8~104.0% within normal values. The inter-day and inter-day precision values were less than 2.4% RSD in the measurement of QC samples. Recoveries of biphenyl from spiked orange samples ranged from 92.7 to 99.4% with RSD between 0.7 and 1.7% at levels of 10, 50, and $100{\mu}g/mL$. The LOD and LOQ were determined to be 0.04 and $0.13{\mu}g/mL$, respectively. These results show that the developed method is appropriate for biphenyl identification and can be used to examine the safety of citrus fruits and surface treatments containing biphenyl residues.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.6
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• pp.586-599
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• 2014

During the last two decades, indoor air quality and volatile organic compounds (VOCs) have been of concern in Korean society due to their nature of potential health impacts. In order to investigate the pollution levels of VOCss in indoor environments, establishment of a solid test method for monitoring the airborne VOCss is essential. In Korea, a method based on adsorbent sampling and GC analysis coupled with thermal desorption was proclaimed as the Korea Standard Method for Indoor Air Quality Test. This study was carried out to examine some inherent problems of the VOCs measurement method. The VOCs method does not describe in detail preparing the standard samples. The standard samples may be prepared by impregnation of either liquid standard solutions or a mixture of standard gases. In this study, we investigated the optimal temperature condition for transferring the liquid standards onto a standard adsorbent tube. As a result, keeping the impregnation temperature at $250^{\circ}C$ will be recommended in regard of the boiling points of multiple target analytes and the thermal stability of the adsorbent. We also demonstrated some problems associated with handling of a syringe used for transferring the standard solutions onto the adsorbent tubes, and a best way to get rid of the syringe problems was suggested. Finally, a number of field works were conducted to evaluate the performance of adsorbent sampling methods. Comparison of different adsorbent tubes, i.e. tube packed with single sorbent (Tenax) and double sorbents (Tenax with Carbotrap), revealed that 30 to 40% differences between the two groups, implying that sampling efficiency is depending on the volatility and the strength of adsorbents. However, duplicate precisions for VOCs sampling with a same type of adsorbent and at same flow rates appeared to be satisfactory to be all within 20%, which is a quality control guideline. Distributed volume precisions were also found to be within a guideline value, 25%, although the precision was in general inferior to the duplicate precision. The Korea indoor VOCs test method should be more refined and improved in many aspects, particularly procedure and instrumentation for preparing the standard samples and specification of quality control assessment.

• Applied Biological Chemistry
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• v.46 no.4
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• pp.361-366
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• 2003

Anti-aflatoxigenic studies on synthetic pyridione alkaloids were conducted. Seven derivatives using piperlongumine as a leading compound were prepared from 3,4,5-trimethoxycinnamic acid (TMCA). These derivatives were analyzed for their structural confrmation and purity by HPLC, GC, GC/MS and $1^H-NMR$. 1-piperidin-1-yl-3-(3,4,5-trimethoxyphenyl)propenone (1) reaction with piperidine; 1-morpholin-4-yl-3-(3,4,5-trimethoypenyl)propenone (2) with morpholine; 1-(3,5-dimethylpiperidin-1-yl)-3-(3,4,5-trimethoxyphenyl)propenone (3) with 3,5-dimethylpiperdine; 1-(2-methylpiperidine-1-yl)-3-(3,4,5-trimethoxyphenyl)propenone (4) with 2-methylpiperidine; 1-(3-hydroxypiperidin-1-yl)-3- (3,4,5-trimethoxyphenyl)propenone (5) with 3-hydroxypiperidine hydrochloride; 1-[3- (3,4,5-trimethoxyphenyl)acryloyl]piperidin-2-one (6) with ${\delta}-valerolactam;\; and\;ethyl\;1-[3-(3,4,5-trimethoxyphenyl)acyloyl]piperidine-4-carboxylate$ (7) with ethyl isonipectotate were synthesized respectively. All derivatives showed an inhibitory activity on aflatoxin $B_1$ production. In conclusion, we believe that they might be an agent for the control of mycotoxin in agricultural commodities.