• Journal of the Korean Geosynthetics Society
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• v.7 no.4
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• pp.1-8
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• 2008

Soil vapor extraction (SVE) is an effective and cost efficient method of removing volatile organic compounds (VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. The aim of this study is to investigate numerically the performance of a prefabricated vertical drain (PVD) as a SVE well, and the pattern of the induced air flow. A validated numerical model for a single PVD extraction well is developed based on the result of a well-designed laboratory model test. The validity of the simple analytical approach to determine air permeability based on the results of model tests is also discussed.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.587-592
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• 2015

Activated carbons (ACs) were treated by fluorination to improve the adsorption property of toluene gas among volatile organic compounds (VOCs). The pore characteristics and surface properties of these activated carbons were evaluated by BET and XPS and the adsorption property and removal efficiency of toluene gas was investigated by gas chromatography. The breakthrough time of fluorinated ACs was increased about 27% compared to that of untreated ACs when the toluene gas of 100 ppm was flowed at a flow rate of $300cm^3/min$. Fluorinated AC of 0.1 g adsorbent totally adsorbed toluene gas in 100 ppm to 100 % during the adsorption time in 19 h. These results can be used as a treatment technology or removal of carcinogenic materials such as toluene.

• Analytical Science and Technology
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• v.17 no.5
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• pp.410-415
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• 2004

In order to learn the emission characteristics of hazardous pollutants associated with environmental tobacco smoking (ETS), we measured the concentrations of major aromatic VOC and carbonyl compounds released from ETS. By acquiring the different smoke types of ETS, we were able to determine that the concentrations of those species range from ppb (normal exhaled air of smoker prior to smoking) to ppm levels (direct release of ETS without filter). Using these measurement data, we also evaluated the body-retaining rate of these compounds as the result of ETS. The results of our analysis indicated that predominant portion of them (e.g., > 99%) are retained as the result of cigarette smoking. To learn more about the potential impact of ETS, more extensive study may be required to assess the gross picture of pollutant deposition inside respiratory intake and their health-effects.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.339-347
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• 2012

This study focuses on developing catalysts for the removal of toluene produced from paint booth. Toluene is one of the major VOC in painting, coating process. Pd catalysts have been used in hydrogenation oxidation and low temperature combustion reaction for toluene removal. Pd catalysts, even though it is very precious and expensive. Therefore, the prepared catalysts from minimizing the amount of Pd ratio (0.1~1.0wt%) were measured. As a result, 1.0wt% Pd(R) catalyst under all conditions showed the highest activity. These results may suggest that the catalytic activity is related to Pd dispersion according sintering atmosphere and Pd ratio in the manufacturing process through the analysis of SEM, XRD.

• Journal of Preventive Medicine and Public Health
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• v.30 no.3 s.58
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• pp.530-539
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• 1997

This study was conducted to assess the health risk on the volatile organic compounds such as toluene, xylene, and styrene in painting workplace. It was monitored through personal air sampling during working time in selected 5 workplaces and analysed using gas chromatography. For the settlement of exposure situation, there were regarded working conditions such as working hours, yearly working days, and working years. Also, Monte-Carlo simulation was used for the induction of hazard index using toxicity value from IRIS(Integrated risk information system) database. The results of risk assessment were summarized as follows. 1. The air concentration of toluene was $7.096{\pm}15,644ppm,\;2.586{\pm}4.275ppm\;for\;xylene,\;1.914{\pm}5.320ppm$ for styrene in blast painting workplaces. The level of toluene was different significantly compared with the level of xylene and styrene. 2. Computated chronic daily intake values of 95th percentile on toluene, xylene and styrene treated by Monte-Carlo simulation were 9.616, 3.567, 2.782 mg/kg/day, respectively. 3. Computated hazard index values of 75th percentile on toluene, xylene and styrene treated by Monte-Carlo simulation were 3.5, 1.0 and 1.6, respectively. Adverse health effects on the toluene, xylene and styrene would be expected by working exposure in selected 5 workplaces since the hazard indices of three compounds were exceeded 1 in the surroundings of 75th percentile though having the low emerged frequency.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.237-242
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• 2021

Simultaneous removal technologies of multi-pollutants such as particulate matters (PMs), NOx, SOx, VOCs and ammonia have received consistent attention due to the enhancement of pollutant abatement efficiency in addition to the stringent environmental regulation and emission standard. Pretreatment of insoluble NO by an ozone oxidation can be considered to be more effective route for saving space occupation as well as operation cost in comparison with that of traditional selective catalytic reduction (SCR) process. Moreover the primary advantage of ozone oxidation process is that the simultaneous removal with acidic gas including SOx is also available. Herein, we highlight recent studies of multi-pollutant abatement via ozone oxidation process and the promising research topics for better application in industrial sectors.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.35-43
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• 2005

Bioslurping combines the three remedial approaches of bioventing, vacuum-enhanced free-product recovery, and soil vapor extraction. Bioslurping is less effective in tight (low-permeability) soils. The greatest limitation to air permeability is excessive soil moisture. Optimum soil moisture is very soil-specific. Too much moisture can reduce air permeability of the soil and decrease its oxygen transfer capability. Too little moisture will inhibit microbial activity. So Modified Fenton reaction as chemical treatment which can overcome the weakness of Bioslurping was experimented for simultaneous treatment. Although the diesel removal efficiency of SVE process increased in proportion to applied vacuum pressure, SVE process was difficulty to remediation quickly semi- or non-volatile compounds absorbed soil strongly. And SVE process had variation of efficiency with distance from the extraction well and depth a air flow form of hemisphere centering around the well. Below 0.1 % hydrogen peroxide shows the potential of using hydrogen peroxide as oxygen source but the co-oxidation of chemical and biological treatment was impossible because of the low efficiency of Modified Fenton reaction at 0.1 % (wt) hydrogen peroxide. NTA was more efficiency than EDTA as chelating agent and diesel removal efficiency of Modified Fenton reaction increased in proportion to hydrogen peroxide concentration. Hexadecane as typical aliphatic compound was removed less than Toluene as aromatic compound because of its structural stability in Modified Fenton reaction. What minimum 10% hydrogen peroxide concentration has good remediation efficiency of diesel contaminated groundwater may show the potential use of Modified Fenton reaction after bioslurping treatment.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.15.2-15.2
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• 2011

비휘발성 저항 메모리소자인 resistance random access memory (ReRAM)는 간단한 소자구조와 빠른 동작특성을 나타내며 고집적화에 유리하기 때문에 차세대 메모리소자로써 각광받고 있다. 현재, 이성분계 산화물, 페로브스카이트 산화물, 고체 전해질 물질, 유기재료 등을 응용한 저항 메모리소자에 대한 연구가 활발히 진행되고 있다. 그 중 ZnO를 기반으로 하는 amorphous InGaZnO (a-IGZO) 박막은 active layer 로써 박막트랜지스터 적용 시 우수한 전기적 특성을 나타내며, 빠른 동작특성과 높은 저항 변화율을 보이기 때문에 ReRAM 에 응용 가능한 재료로써 기대되고 있다. 또한 가시광선 영역에서 광학적으로 투명한 특성을 보이기 때문에 투명소자로서도 응용이 기대되고 있다. 본 연구에서는 indium tin oxide (ITO) 투명 전극을 적용한 ITO/a-IGZO/ITO 구조의 투명 소자를 제작하여 저항 메모리 특성을 평가하였다. Radio frequency (RF) sputter를 이용하여 IGZO 박막을 합성하고, ITO 전극을 증착하여 투명 저항 메모리소자를 구현하였고, resistive switching 효과를 관찰하였다. 또한, 열처리를 통해 a-IGZO 박막 내의 Oxygen vacancy와 같은 결함의 정도에 따른 on/off 저항의 변화를 관찰할 수 있었다. 제작된 저항 메모리소자는 unipolar resistive switching 특성을 보였으며, 높은 on/off 저항의 차이를 유지하였다. Scanning electron microscope (SEM)을 통해 합성된 박막의 형태를 평가하였고, X-ray diffraction (XRD) 및 transmission electron microscopy (TEM)을 통해 결정성을 평가하였다. 제작된 소자의 전기적 특성은 HP-4145 를 이용하여 측정하고 비교 분석하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.1
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• pp.39-44
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• 2002

To obtain the repression of off-odor and the improvement of food quality in b1ack bean chungkugjang (BBC), some baste components of BBC added with kiwi (BBCK) or radish (BBCR) and fermented at 42$^{\circ}C$ for 3 days were investigated. Although contents of free amino acids in BBC were lower than those of soybean chung-kugjang (SC), they increased by adding kiwi and radish homogenate to black bean, indication that two materials were effective to the enzymatic digestibility of soy protein during fermentation. Among organic acids, citric acid was the most abundant, followed by acetic acid and lactic acid. Fatty acid composition was high in the order of linoleic acid (44.28~54.24%), oleic acid (18.18~22.10%) and palmitic acid(9.93~15.51%). There was no significant difference in compositions of organic acids and fatty acids of chungkugjangs. Majar volatile compounds of BBC were 2.5-dimethyl parazine and trimethyl pyrazine. Contents of alkyl pyrazines that of contribute the characteristic aroma and flayer of BBCK and BBCR decreased as compared with those of SC, respectively. Uracil and UMP were major nucleic acid-related compounds in all four types chungkugjangs. Contents of the other nucleic acid-related compounds showed a similar trend in all chungkugjangs. In sensory evaluation, kiwi and radish were effective to repression of off-odor from chungkugjang. Sweet taste of stew of black bean chungkugjang was strong as compared with that of soybean chungkugjang, indicating that palatability of BBCK or BBCR was good.

• Analytical Science and Technology
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• v.15 no.1
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• pp.80-86
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• 2002

The simultaneous analysis of the odorous compounds designated by law in Korea and Japan was examined with the thermal desorber gas chromatography-mass spectrometry using one column. The approximate concentrations of trimethyl amine, acetaldehyde, methyl mercaptan and dimethyl sulfide were estimated. Styrene, dimethyl disulfide, propionaldehyde, n-butyl aldehyde, i-butyl aldehyde, n-valeraldehyde, i-valeraldehyde, ethyl acetate, toluene, xylene, methyl i-butyl ketone and i-butanol were detected at concentrations of the detection limits of their threshold values. As a typical example of simultaneous analysis of the odorous compounds, the volatile organic compounds emitted from compost procedure of food waste were concentrated and analyzed with thermal desorber/GC/MSD, and major malodorous compounds were estimated from the concentrations and threshold values of the detected components. From the result of analysis, 34 compounds were confirmed and among them, trimethyl amine, i-valeraldehyde, methyl mercaptan, methyl allyl sulfide, dimethyl sulfide, acetaldehyde, ethanol, n-butyaldehyde were expected to attribute to the odor in order of strength.