• 한국대기환경학회지
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• 제30권4호
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• pp.362-377
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• 2014

Polycyclic aromatic hydrocarbons (PAHs) have been of particular concern since they are present both in the vapor and particulate phases in ambient air. In this study, a simple method was applied to determine the vapor phase PAHs, and the performance of the new method was evaluated with a conventional method. The simple method was based on adsorption sampling and thermal desorption with GC/MS analysis, which is generally applied to the determination of volatile organic compounds (VOCs) in the air. A combination of Carbotrap (300 mg) and Carbotrap-C (100 mg) sorbents was used as the adsorbent. Target compounds included two rings PAHs such as naphthalene, acenaphthylene, and acenaphthene. Among them, naphthalene was listed as one of the main HAPs together with a number of VOCs in petroleum refining industries in the USA. For comparison purposes, a method based on adsorption sampling and solvent extraction with GC/MS analysis was adopted, which is in principle same as the NIOSH 5515 method. The performance of the adsorption sampling and thermal desorption method was evaluated with respect to repeatabilities, detection limits, linearities, and storage stabilities for target compounds. The analytical repeatabilities of standard samples are all within 20%. Lower detection limits was estimated to be less than 0.1 ppbv. In the results from comparison studies between two methods for real air samples. Although the correlation coefficients were more than 0.9, a systematic difference between the two groups was revealed by the paired t-test (${\alpha}$=0.05). Concentrations of two-rings PAHs determined by adsorption and thermal desorption method consistently higher than those by solvent extraction method. The difference was caused by not only the poor sampling efficiencies of XAD-2 for target PAHs and but also sample losses during the solvent extraction and concentration procedure. This implies that the levels of lower molecular PAHs tend to be underestimated when determined by a conventional PAH method utilizing XAD-2 (and/or PUF) sampling and solvent extraction method. The adsorption sampling and thermal desorption with GC analysis is very simple, rapid, and reliable for lower-molecular weight PAHs. In addition, the method can be used for the measurement of VOCs in the air simultaneously. Therefore, we recommend that the determination of naphthalene, the most volatile PAH, will be better when it is measured by a VOC method instead of a conventional PAH method from a viewpoint of accuracy.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.3049-3052
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• 2009

Methyl tert-butyl ether (MTBE) is added to gasoline to enhance the octane number of gasoline, tert-butyl alcohol (TBA) is major degradation intermediate of MTBE in environment, and benzene, toluene, ethyl benzene and xylene (BTEX) are also major constituents of gasoline. In this study, a simplified headspace analysis method was adapted for simultaneous determination of MTBE, TBA and BTEX in ground water samples. The sample 5.0 mL and 2 g NaCl were placed in a 10 mL vial and the solution was spiked with fluorobenzene as an internal standard and sealed with a cap. The vial was placed in a heating block at 85 $^{\circ}C$ for 30 min. The detection limits of the assay were 0.01 ${\mu}$g/L for MTBE and BTEX, and 0.02 ${\mu}$g/L for TBA. The method was used to analyze 110 ground water samples from various regions in Korea, and to survey the their background concentration in ground water in Korea. The samples revealed MTBE concentrations in the range of 0.01 - 0.45 ${\mu}$g/L (detection frequency of 57.3%), TBA concentrations in the range of 0.02 - 0.08 ${\mu}$g/L (detection frequency of 5.5%), and total BTEX concentrations in the range of 0.01 - 2.09 ${\mu}$g/L (detection frequency of 87.3%). The developed method may be used when simultaneously determining the amount of MTBE, TBA and BTEX in water.

• 한국항행학회논문지
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• 제27권6호
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• pp.865-870
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• 2023

본 논문은 LiDAR (light detection and ranging) 센서를 활용하여 블랙아이스를 검출하는 새로운 방법을 제안합니다. 센서는 작고 비용이 저렴하면서도 높은 정확성을 가진 거리 측정 센서로 온도와 경사각을 다르게 하여 아스팔트와 블랙아이스의 각도를 구별하는 데 사용됩니다. 이 센서의 거리 측정 오차율은 대략 ±1 cm로 블랙아이스와 아스팔트을 구별하는 데에는 일부 오차가 발생할 수 있습니다. 본 논문에서는 정확성을 높이기 위한 추가적인 연구와 개선이 필요함을 지적하며 이를 통해 더욱 정확한 블랙아이스 검출 방법을 제안합니다.

• Journal of Pharmaceutical Investigation
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• 제22권3호
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• pp.197-204
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• 1992

A gas chromatographic method using nitrogen phosphorous selective detection was developed for simultaneous determination of haloperidol and its metabolite, reduced haloperidol, in human plasma. Combelen was used as internal standard, The method involved extraction and trimethylsilylation followed by the injection of $2-4\;{\mu}l$ of benzene layer, which was used to dissolve the trimethylsilylated derivatives of haloperidol and reduced haloperidol, onto SE-54 column [5% phenyl methyl silica fused capillary column, $16m{\times}0.22\;mm$ $(I.D.){\times}0.33\;{\mu}m$ (coated thickness)]. The temperature of column oven was programmed from $200^{\circ}C\;to\;300^{\circ}C$ at the increase rate of $10^{\circ}C/min and also the temperatures of injector and detector were set at $300^{\circ}C$. Helium was used as carrier gas and its flow rate was maintained at 30 ml/min. The detection was conducted with nitrogen phosphorous selective detector. The retention times for combelen, reduced haloperidol and haloperidol were found to be 9.14, 9.75 and 9.99 min, respectively. The detection limits for haloperidol and reduced haloperidol in human plasma were both 0.2 ng/ml. The coefficients of variation of the intra-assay were generally low (below 9.8%). The mean absolute recoveries of added haloperidol and reduced haloperidol from plasma were 72% and 84%, respectively. No interferences from endogenous substances were found.

• 한국전자거래학회지
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• 제21권1호
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• pp.105-118
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• 2016

게임회사는 온라인 게임을 서비스하는 과정에서 공격자의 공격을 자주 받는다. 본 논문에서는 온라인 게임에서 해킹 모듈을 탐지하는 방식 중 하나인 Signature 탐지 방식의 한계점을 분석하고, 이러한 문제점을 보완하기 위한 Scoring Signature 탐지 방식을 제안하고자 한다. Scoring Signature 탐지 방식은 알려지지 않은 해킹 공격에 대한 수집 및 탐지를 가능토록하여 기존의 Signature 탐지 방식보다 20배 이상의 탐지 성과로 나타났다. 이 방식을 기존에 탐지하고 있는 방식과 병행하여 적용하면 해킹 모듈 수집에 대한 번거로움을 최소화하고 미탐지로 인한 게임내의 해킹 모듈 사용도 크게 감소시킬 수 있을 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1693-1698
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• 2012

A headspace gas chromatographic mass spectrometric (GC-MS) assay method was developed for the simultaneous determination of methyl tertiary butyl ether (MTBE), $tert$-butyl alcohol (TBA) and benzene, toluene, ethyl benzene and xylene (BTEX) in soil contaminated with gasoline. 2 g of soil sample were placed in a 10 mL headspace vial filled with 5 mL of phosphoric acid solution (pH 3) saturated with NaCl, and the solution was spiked with fluorobenzene as an internal standard and sealed with a cap. The vial was heated in a heating block for 40 min at $80^{\circ}C$. The detection limits of the assay were 0.08-0.12 ${\mu}g$/kg for the analytes. For five independent determinations at 10 and 50 ${\mu}g$/kg, the relative standard deviations were less than 10%. The method was used to analyze fifty six soil samples collected from various regions contaminated with gasoline in Korea. The developed method may be valuable for the monitoring of the analytes in soil.

• 한국환경과학회지
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• 제12권4호
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• pp.477-480
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• 2003

Pesticides were extracted from samples with 70% acetone and methylene chloride in order, and then cleaned up via open-column chromatography apparatus packed with florisil, and finally analyzed simultaneously the organochlorine and pyrethroid pesticides using GC(ECD). An ultra-2 fused silica capillary column was used to separate and identify the products. The resolution between the last isomeric peak of cypermethrin(59.987min) and the first isomeric peak of flucythrinate(60.043min) was not satisfactory. The last isomeric peak of fenvalerate(62.344min) and the first isomeric peak of fluvalinate(62.397min) were overlapped. Recoveries of soybean sample fer the most pesticides were 73.3% to 102.4%. Detection limits were between 0.004 and 0.063 ${\mu}$g/mg when this method was used.

• 한국정밀공학회지
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• 제18권9호
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• pp.171-178
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• 2001

The nonlinearity of a laser interferometer usually ranges from sub-nanometer to several manometers. This nonlinearity, which has periodic characteristics, limits the accuracy of the interferometer at the sub-nanometer level. The nonlinearity error of the one-frequency homodyne interferometer with quadrature fringe detection results from a number of factors including polarization mixing by imperfect optical elements, unequal gain of photo detectors, lack of quadrature between two signals and misalignment. In this paper, we described a method for measuring and compensating the nonlinearity of homodyne interferometer using the elliptical fitting technique with least-square method. Experimental results demonstrate that $^\pm$3.5 nm nonlinearity can be reduced to $^\pm$0.2 nm level.

• 한국환경과학회지
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• 제12권1호
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• pp.81-86
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• 2003

The study was carried out to evaluate the new analytical method of phthalate esters(diethylphthalate, di-n-butylphthalate, butylbenzylphthalate, bis(2-ethylhexyl)phthalate), one of the endocrine disruptors, which were performed by GC/MS-SIM(selected ion monitoring). The phthalate esters were extracted from water samples using solid-phase extraction on $C_{18}$ columns. It investigated that the extraction recovery rate of phthalate esters with different solvents and solvent volume. The optimal solvent was dichloromethane and proper volume of dichloromethane for recovery of phthalate esters was 4 mL. There were good linearities(above $R^2$=0.9975) in the range 0.01~0.50mg/L, and the detection limits were below 0.01~0.03$\mu\textrm{g}$/L. The recovery rates, RSD and MDLs for phthalate esters were 80~114%, 5.0~8.1% and 0.03~0.11$\mu\textrm{g}$/L, respectively. This method shows a good precision of phthalate esters.

• 분석과학
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• 제8권4호
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• pp.771-778
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• 1995

The authors have developed an analytical method for determining trace amounts of 285 kinds of chemicals in natural waters by GC-ion trap MS. The results of overall recovery tests at $0.1{\mu}g/l$ showed that the mean recovery was 92.1% and the mean relative standard deviation was 10.8%. The mean of the method detection limits was $0.036{\mu}g/l$. From the results of analysis of real samples, it was confirmed that this method is useful to elucidate the concentration levels and the fate of chemicals in the aquatic environment.