• Journal of Soil and Groundwater Environment
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• v.24 no.5
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• pp.11-16
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• 2019

In this study, a reliable number of soil samples for TPH fractionation was investigated in order to perform risk assessment. TPH was fractionated into volatile petroleum hydrocarbons (VPH) with three subgroups and extractable petroleum hydrocarbons (EPH) with four subgroups. At the study site, concentrations of each fraction were determined at 18 sampling points, and the 95% upper confidence limit (UCL) value was used as an exposure concentration of each fraction. And then, 5 sampling points were randomly selected out of the 18 points, and an exposure concentration was calculated. This process was repeated 30 times, and the results were compared statistically. Exposure concentrations of EPH obtained from 18 points were 99.9, 339.1, 27.3, and 85.9 mg/kg for aliphatic $C_9-C_{18}$, $C_{19}-C_{36}$, $C_{37}-C_{40}$, and aromatic $C_{11}-C_{22}$, respectively. The corresponding exposure concentrations obtained from 5 points were 139.8, 462.8, 35.1 and 119.4 mg/kg, which were significantly higher than those from 18 points results (p <0.05). Our results suggest that limited number of samples for TPH fractionation may bias estimation of exposure concentration of TPH fractions. Also, it is recommended that more than 30 samples need to be analyzed for TPH fractionation in performing risk assessment.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.793-800
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• 2008

Recently domestic drinking water industry has recognized membrane-based technology as a promising alternative for water treatment. To ensure successful application of membrane processes, the integrity of membrane systems should be maintained. According to US EPA guidance, the pressure decay test based on the bubble point theory is recommended to detect any membrane defection of which size is close to the smallest diameter of Cryptosporidium oocysts, $3{\mu}m$. Proper implementation of the pressure decay test is greatly affected by initial test pressure, and the interpretation of the test results is associated with upper control limit. This study is conducted to investigate various factors affecting determination of initial test prtessure and upper control limit, including membrane-based parameters such as pore shape correction factor, surface tension and contact angle, and system-based parameters, such as volumetric concentration factor and total volume of system. In this paper, three different hollow fibers were used to perform the pressure decay test. With identical initial test pressure applied, their pressure decay tendency were different from each other. This finding can be explained by the micro-structure disparity of those membranes which is verified by FESEM images of those membranes. More specifically, FESEM images revealed that three hollow fibers have asymmetry, deep finger, shallow finger pore shape, respectively. In addition, sensitivity analysis was conducted on five parameters mentioned above to elucidate their relation to determination of initial test pressure and upper control limit. In case of initial pressure calculation, the pore shape correction factor has the highest value of sensitivity. For upper control limit determination, system factors have greater impact compared to membrane-based parameters.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.744-756
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• 2018

The purpose of this study was to investigate the anti-inflammatory effect and the antimicrobial activity to skin flora of essential oil from rosemary that naturally grown in Jeju. rosemary essential oil was extracted by water distillation essential oil extraction method. In order to confirm the anti-inflammatory activity of rosemary essential oil, it was confirmed that the production of NO and $PGE_2$ induced by LPS in RAW 264.7 cells was inhibited in a concentration-dependent manner. Western blot analysis showed that the expression of iNOS and COX-2, which are biosynthetic enzymes, decreased in a concentration-dependent manner. In addition, production of $TNF-{\alpha}$ and IL-6 the pro-inflammatory cytokines were inhibited. Antimicrobial activities of three S. epidermidis and three P. acnes strains including two antibiotic resistant strains were observed in paper disc method and MIC and MBC tests showed inhibition of bacterial growth and death. From the results of the experiment, we confirmed that rosemary essential oil has the anti-inflammatory and antimicrobial efficacy and it could be used as a cosmetic and skin care material in the future.

• Membrane Journal
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• v.32 no.4
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• pp.253-263
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• 2022

This study suggests a guideline for designing unit process of wastewater reuse in terms of a maintenance of the process based on critical parameters to draw a high quality performance of RO unit. Defining the parameters was done by applying membrane integrity test (MIT) in pretreatment process utilizing lab-scale MF. SDI is utilized for judging whether permeate is suitable to RO unit. However, result said TOC concentration matching with particle count analysis is better for judging the permeate condition. When membrane test pressure (P_test) was measured to derive log removal value in PDT, virgin state of membrane fiber was used to measure dynamic contact angle utilizing surface tension of the membrane fiber. Actually, foulant affects to the state of membrane surface, and it decreases the P_test value along with time elapsed. Consequently, LRV_DIT is also affected by P_test value. Thus, sensitivity of direct integrity test descends with result of P_test value change, so P_test value should be considered not the virgin state of the membrane but its current state. Overall, this study focuses on defining design parameters suitable to MF pretreatment for RO process in wastewater reuse by assessing its impact. Therefore, utilities can acknowledge that the membrane surface condition must be considered when users conduct the direct integrity test so that P_test and other relative parameter used to calculate LRV_DIT are adequately measured.