• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1260-1269
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• 2018

Production of good Koji primarily depends upon the selection of substrate materials and fermentative microflora, which together influence the characteristic flavor and aroma. Herein, we performed comparative metabolomic analyses of volatile organic compounds (VOCs) and primary metabolites for Koji samples fermented individually with Bacillus amyloliquefaciens and Aspergillus oryzae. The VOCs and primary metabolites were analyzed using headspace solid phase microextraction (HS-SPME) followed by gas chromatography time-of-flight mass spectrometry (GC-TOF-MS). In particular, alcohols, ketones, and furans were mainly detected in Bacillus-fermented Koji (Bacillus Koji, BK), potentially due to the increased levels of lipid oxidation. A cheesy and rancid flavor was characteristic of Bacillus Koji, which is attributable to high content of typical 'off-flavor' compounds. Furthermore, the umami taste engendered by 2-methoxyphenol, (E,E)-2,4-decadienal, and glutamic acid was primarily detected in Bacillus Koji. Alternatively, malty flavor compounds (2-methylpropanal, 2-methylbutanal, 3-methylbutanal) and sweet flavor compounds (monosaccharides and maltol) were relatively abundant in Aspergillus-fermented Koji (Aspergillus Koji, AK). Hence, we argue that the VOC profile of Koji is largely determined by the rational choice of inocula, which modifies the primary metabolomes in Koji substrates, potentially shaping its volatolome as well as the aroma characteristics.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.580-587
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• 2017

Woodfiber insulation board can be considered as a one of the key material for low energy consumption, comfortable and safety construction of residential space because of its eco-friendly and high thermal insulation performance. This study was carried out to investigate the formaldehyde (HCHO) total volatile organic compounds (TVOC) emission properties and combustion shapes by flame test of low density fiberboards (LDFs) prepared with different adhesives. HCHO TVOC emission and combustion properties of LDFs prepared by melamine urea formaldehyde (MUF), phenol formaldehyde (PF), emulsified methylene diphenyl diisocyanate (eMDI) and latex resin adhesives were measured by desiccator method, 20 L chamber method, and flame test, respectively. As results, LDFs manufactured by MUF, eMDI and latex resin adhesives satisfied the Super $E_0$ grade of HCHO emission performance except PF resin. Furthermore, TVOC emission of all LDFs were satisfied the Korean indoor air quality standard (below $400{\mu}g/m^2{\cdot}h$). Especially, LDF with eMDI resin adhesive showed the lowest HCHO and TVOC emissivity, that $0.14mg/{\ell}$, $12{\mu}g/m^2{\cdot}h$, respectively. However, eMDI emitted the small amount ($3{\mu}g/m^2{\cdot}h$) of toluene in VOC components. In the flame test, LDF with MUF resin adhesives showed the most favorable shape after flame test compare to LDFs prepared other adhesives. Based on HCHO and TVOC emission, and combustion shapes, MUF resin adhesive may be recommended to prepare LDF for insulation purpose.

• Environmental Analysis Health and Toxicology
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• v.11 no.1_2
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• pp.19-29
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• 1996

Human exposure to volatile compounds in tap water can occur from inhalation and dermal absorption as well as direct ingestion. The relative contribution to total human exposure from these pathways has been considered to be important especially for VOC's (volatile organic compounds). In an attempt to reduce the uncertainty of the risk assessment, it has been suggested that the exposure assessment process could be significantly improved by adopting Monte-Carlo simulation. However, there is no actual data in Korea for each exposure parameter to determine the level of exposure, and the distributional pattern. Therefore, we surveyed water use patterns and behavior related to multi-route exposure to VOC's in household tap water in Korea, and compared these values to the those in western countries. In the first survey, we calculated daily water intake using data from a sample of 1322 persons of several cities in Korea. In the second survey, we obtained questionnaire data on exposure time for showering, bathing and household activities, and tap water intake from 851households in Korea. In the last survey, we measured the exposure parameters (exposure time, water use rate etc.) related to showers, baths, toilets, dish washing, washing and cooking, and tap water intake was surveyed. Also, the subjects were measured their body weight, height and tidal volume, etc. A diary, a flow meter and a measuring cup were used to measure these values as precisely as possible. Average daily water intake was ranged 0.79-1.71 L/day for adults in three surveys. Tap water intake measured by log-sheet during one week in third survey was 1.26 (average), 1.98 L/day (90 percentlie), respectively. These results were comparable with results from EPA (1.4, 2L/day). The average amount of water used by housewives in the third survey was 515.0 $\pm$ 564.6L/day. In usual activity, the amount of water used in the bathroom, the laundry and the kitchen was 140.0 $\pm$ 538.9, 148.0 $\pm$ 174.5, 229.3 $\pm$ 205.4 L/day, respectively. Exposure parameters such as water intake rate, exposure duration, body weight, inhalation rates in surveyed data of Korean people differed from those published from western countries. This could be attributed to variations in lifestyle, dietary habits and physiological characteristics.

• Journal of Environmental Impact Assessment
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• v.32 no.5
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• pp.353-362
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• 2023

TOC, which can measure more than 90% of organic substances, can be measured quickly and easily,replacing BOD and COD, which were indicators of organic pollutants. According to water quality pollution control standards, when measuring TOC, if the inorganic carbon ratio in the sample is over 50%, the NPOC (Non-Purgeable Organic Carbon) method should be used. If volatile organic compounds (VOCs) are present at a certain concentration, the TC-IC (subtracting inorganic carbon from total carbon) method should be used. To validate the limitations of these analytical conditions, experiments were conducted by varying the ratio of TOC to IC in purified water and measuring the concentration of TOC in test solutions. The results showed no significant difference between the TC-IC method and the NPOC method. When measuring samples with added VOC standard solutions, it was observed that the carbon loss due to purging was not significant when using the NPOC method. Therefore, it is concluded that the choice of analytical method does not lead to significant differences when VOCs are present in the sample. To account for potential variations in results based on water quality pollution control standards and regulations regarding the approval and testing of environmental measurement devices, a comparison of field sample concentration values was made using two widely used types of TOC analyzers in Korea. The results showed variations of 0.02 to 0.83 mg/L between methods depending on the manufacturer, highlighting the need for caution when selecting an instrument.

• Analytical Science and Technology
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• v.20 no.6
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• pp.453-459
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• 2007

This study is for investigation of indoor conditions with air contamination after occupation 120 households in brand-new apartments by measuring the concentration of VOCs and carbonyl compounds. It has been found that TVOC (total volatile organic compounds; TVOCs) were $688.61{\mu}g/m^3$ after moving in. And formaldehyde, toluene, m, p-xylene, acetone and ethylbenzene were $158.56{\mu}g/m^3$, $146.58{\mu}g/m^3$, $69.28{\mu}g/m^3$, $63.80{\mu}g/m^3$ and $29.65{\mu}g/m^3$, respectively. The mean concentrations of indoor air pollutants tend to decrease along an increase dwelling period. But, the mean concentration of d-limonene increased from 2 months to 10 months. Also, toluene, ethylbenzene, m, p, o-xylene amounted to 38.8 % among VOCs studied, this ratio tend to decrease along with and increased dwelling period.

• Journal of environmental and Sanitary engineering
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• v.16 no.4
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• pp.69-76
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• 2001

The catalytic oxidation of volatile organic compounds (VOCs), which were benzene and toluene, was studied in the supercritical carbon dioxide($SC-CO_2$) media. In $SC-CO_2$ media, the deep oxidation conversion of VOCs was increased with the temperature and pressure. The deep oxidation conversion in SC -$CO_2$ media is better than that in air media at same pressure condition. This can be explained by the solubility of VOCs in $SC-CO_2$. The many intermediates produced by the partial oxidation of VOCs were detected from off-line samples. The intermediates were Identified as benzene, toluene, benzaldehyde, phenol, naphthalene, 1,1`-biphenyl, benzoic acid, 3-methylphenol, 1,1'-(1,2-ethanediyl)bis- benzene, 1,1'-(1,2-ethene- diyl)bis-benzene, anthracene, and so on. The amount of intermediates was decreased as the molar radio of oxygen to carbon dioxide was decreased. When the molar ratio of oxygen to carbon dioxide was 1 : 16, the deep conversion was kept constant. Thus, the catalytic oxidation process in $SC-CO_2$ media can be combined on-line with supercritical fluid extraction of environmental matrices and supercritical regeneration of used adsorbent. Thus, the nontoxic $SC-CO_2$ media process was suggested as the new VOCs control technology.

• Journal of the Korean housing association
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• v.21 no.6
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• pp.11-18
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• 2010

The aims of this study were to grasp the real condition state and clarify the characteristics and influence of pollutants on the indoor air pollution in occupied apartment units. The research method was to measure the pollution levels of indoor air pollution, and investigate characteristics of the pollutants such as the outdoor environment, elapsed time after construction, finished materials, temperature, relative humidity, space extension, purchase with furniture and electric appliances, built-in closets, and method for cleaning the air. And these were made a comparition between industrial and residential area. The VOCs and formaldehyde concentration in indoor air were measured the 6 household in residental area and 5 household in industrial area. In conclusion, the concentration such as benzene, ethylbenzene, toluene, xylene, styrene showed the pollution state within permissible levels, however formaldehyde concentration has need a lot of attention as ever. And it turned out that the influence with reference to emission from building materials on indoor air pollution lessened under 18 months elapsed time after construction.

• Journal of Sensor Science and Technology
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• v.20 no.5
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• pp.305-310
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• 2011

This study focuses on the fabrication of $TiO_2$ nanosheets and their gas sensor application. A simple sonochemical method is employed to fabricate the $TiO_2$ nanosheets. The obtained samples were investigated by transmission electron microscope(TEM) and X-ray Diffraction(XRD). The $TiO_2$ nanosheets were coated on substrates by a dropping method followed by heat treatment. The sensor responses to volatile organic compounds(VOCs) such as toluene, benzene, ethanol and acetaldehyde were studied. It was found that the $TiO_2$ nanosheets sensors are able to detect ppb-levels of VOC gases.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.145-151
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• 2006

As the concerns about indoor air quality (IAQ) increase in recent years, lots of research works are under way to investigate the influence of volatile organic compounds (VOCs) emitted from building products on the IAQ. One of the regulations for the IAQ is the level of total VOCs (TVOCs) from building products, assuming that the TVOCs are suspected to cause many health problems such as skin irritation, asthma, and allergy. However, the presence of biogenic VOCs, or natural VOCs (NVOCs) is believed to be beneficial to human health. Therefore, this study attempted to investigate chemical species and the NVOCs compositions of solid lumbers from different wood species. It was found that major VOC components were monoterpenes such as $\alpha$-pinene, $\beta$-pinene, d-limonene, camphene, $\alpha$-terpinene, $\gamma$-terpinene etc.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.667-673
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• 2005

An EBeam (electron beam)-catalyst coupling technique has been developed to control aromatic volatile organic compounds (VOCs) by annexing the catalyst with already existing EBeam technology. In this study, toluene emitted from various industrial coating processes was selected as a representative VOC. The concentration of toluene of concern was 200 ppm. There was an increase in the removal efficieny of toluene by increasing the absorbed dose (kGy) in the EBeam-only and the EBeam-catalyst coupling systems. Compared to EBeam-only system under the same existing EBeam-Pt $1\%$ coupling conditions, EBeam-Pt $1\%$ coupling system revealed 36, 29, 30$\%$ increase in toluene treatmenet at (5, 6.7, 8.7 kGy), respectively. In addition, $O_{3}$ was decreased and CO, $CO_{2}$ were increased by increasing the absorbed dose (kGy) in the EBeam-catalyst (Pt $1\%$, Cu $1\%$) coupling systems. Therefore, it was concluded that the EBeam-catalyst coupling system had a synergy effect on toluene control, compared to the EBeam-only system.