• Journal of Sensor Science and Technology
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• v.13 no.1
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• pp.41-46
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• 2004

There is currently much interest in the development of instruments that emulate the senses of humans. Increasingly, there is demand for mimicking the human sense of smell, which is a sophisticated chemosensory system. An electronic nose system is applicable to a large area of industries including environmental monitoring. We have designed a protable electronic nose system using an array of commercial chemical gas sensors for recognizing and analyzing the various odours. In this paper, we have implemented a portable electronic nose system using an array of gas sensors for recognizing and analyzing VOCs (Volatile Organic Compounds) in the field. The accuracy of a portable electronic nose system may be lower than an instrument such as GC/MS (Gas Chromatography/Mass Spectrometer). However, a portable electronic nose system could be used on the field and showed fast response to pollutants in the field. Several different algorithms for odours recognition were used such as BP (Back-Propagation) or LM-BP (Levenberq-Marquardt Back-Propagation). We applied RBF (Radial Basis Function) Network for recognition and quantifying of odours, which has simpler and faster compared to the previously used algorithms such as BP and LM-BP.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.5
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• pp.461-476
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• 2014

Continuous Water-Soluble Organic Carbons (WSOC) by the Particle Into Liquid Sampler - Total Organic Carbon (PILS-TOC) analyzer were measured at the Seoul intensive monitoring site from June 17 through July 5 in 2014. In addition, the 24 hour integrated PM2.5 collected by Teflon and Quartz filters were analyzed for water soluble ions by Ion chromatography (IC), WSOC by TOC from water extracts, organic carbon (OC), elemental carbon (EC) by carbon analyzer using the thermal optical transmittance (TOT) method, and mass fragment ions (m/z) related to alkanes and PAHs (Poly Aromatic Hydrocarbons) by Gas Chromatography-Mass Spectrometer-Thermal Desorption (GC/MS-TD). Based on the statistical analysis, four different Carbonaceous Thermal Distributions (CTDs) from OCEC thermal-gram were identified. This study discusses the primary and secondary sources of WSOC based on the Classified CTD, organic mass fragments, and diurnal patterns of WSOC. The results provide knowledge regarding the origins of WSOC and their behaviors.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.238-252
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• 2002

In order to screen out indicators for the discrimination of ginseng habitat, some physical and chemical characteristics of Korean red ginsengs (94 kinds) and Chinese red ginsengs (50 kinds) were analyzed by using a rheometer, an electronic nose system, a combined technique of solid phase micro-extraction (SPME) and gas chromatograph equipped with an electron capture detector (GC/ECD), an X-ray fluorescence spectrometer (XRF), an inductively coupled plasma mass spectrometer (ICP/MS), a near infrared spectrometer (NIRs) and high performance liquid chromatography equipped with evaporative light scattering detector (HPLC/ELSD). The results are summarized as follows: (i) The rhizome strengths of Korean red ginsengs were significantly higher than those of Chinese red ginsengs. (ii) The electronic nose patterns of Korean red ginsengs were significantly different from those of Chinese red ginsengs. (iii) Some unidentified peaks were detected not in the headspace of Korean red ginsengs but in the headspace of Chinese red ginsengs when the headspace volatiles prepared by the SPME technique were analyzed by GC/ECD. (iv) Either the content ratios of K to Ca or Mn to Fe were significantly different between Korean red ginsengs and Chinese red ginsengs. (v) The reflectance ratios of NIRs wavenumbers such as $904\;cm^{-1}\;to\;1088\;cm^{-1}$ for Korean red ginsengs were significantly different from those for Chinese red ginsengs. (vi) The content ratios of ginsenoside-Rg to ginsenoside-Re of Korean red ginsengs were significantly higher than those of Chinese red ginsengs. These results indicate that the rhizome strength, the electronic nose pattern, the occurrence of ECD-sensitive headspace volatile components, the content ratios of K to Ca and Mn to Fe, the NIRs pattern and the content ratio of ginsenoside-Rg to -Re may be indicators for the discrimination of ginseng habitat.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.244-250
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• 2007

Membrane inlet mass spectrometer (MIMS) has been used to accurately quantify dissolved gases in liquid samples. In this study, the MIMS system was applied to measure dissolved methane in seawater and sediment porewater. To evaluate the accuracy of the measurement, liquid samples saturated with different methane partial pressure were prepared and the methane concentrations were quantified with the MIMS system. The measured values correspond well with the expected values calculated from solubility constants. The standard error of the measurements were $0.13{\sim}0.9%$ of the mean values. The distribution of dissolved methane concentration in seawater of the South Sea of Korea revealed that the physical parameters primarily control the methane concentration in sea water. The MIMS system was effective to resolve the small dissolved methane difference among water masses. The probe type inlet in MIMS system was proven to be effective to measure porewater methane concentration.

• Analytical Science and Technology
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• v.5 no.2
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• pp.169-176
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• 1992

Analytical detection limits and Relative Ion Yield (RIY) by a jet type ion source glow discharge mass spectrometer(GD/MS) have been measured. With a jet type ion source, the sample loss rate for a Cu sample is 0.23 mg/min with 0.1 L/min gas flow rate and 0.11 mg/min with no gas flow rate. However, the ion intensity of Cu does not change significantly with thee variation of the gas flow rate. The RIY values obtained from the calibration curves of the six copper based standards were between 0.57 of Fe and 3.5 of Cr. The detection limits of most elements were in the range of 0.9 and 2.0 ppm when the glow discharge was operated at 4 mA, 1000V.

• Analytical Science and Technology
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• v.21 no.6
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• pp.495-501
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• 2008

Agilent 5973 GC-MS instrument was modified so that the capillary direct interface was removed and that a silicone membrane was installed between GC and MS. Feasibility study of the membrane interface GC-MS has been carried out. Vacuum of the mass spectrometer was not affected by the carrier gas flow rate up to $4.7m{\ell}/min$. As the carrier flow rate was increased, peak tailing was reduced and chromatogram peaks appeared earlier. Chromatogram peaks showed better separation and higher sensitivity as the membrane thickness was reduced from $127{\mu}m$ to $75{\mu}m$, and also as the interface temperature was increased. However, the membrane interface GC-MS had drawbacks such as background ions at 73 and 147 m/z and poor peak separation due to peak tailing.

• Korean Journal of Food Science and Technology
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• v.51 no.1
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• pp.12-17
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• 2019

Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in fresh-cut salads available from the market were determined by gas chromatography-mass spectrometry (GC-MS). The target compounds in 3 g of acidified homogenates were extracted with 20 mL of methyl t-butyl ether (MTBE). The extract was concentrated to 1 mL and heated for 1 h at $55^{\circ}C$. The analytes were separated using a DB-1701 column and detected with a mass spectrometer. The method detection limit was approximately $6{\mu}g/kg$, and both analytical accuracy and precision were found to be satisfactory. The linearity of the calibration curves expressed as the coefficients of determination was >0.996. The analysis of seven samples using the established method showed that the four samples contained considerable amounts of analytes ($25.4-31.2{\mu}g/kg$ of DCAA and $18.8-46.1{\mu}g/kg$ of TCAA). These results raised a concern about the impact of fresh-cut salad consumption on human health.

• Journal of Environmental Health Sciences
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• v.40 no.6
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• pp.442-453
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• 2014

Objectives: Persistent organic pollutants (POPs) are known to be the detrimental chemicals in the body, even at low levels, and are stored in adipose tissue. Recently, POPs have been reported to be associated with chronic diseases, including cancer and cardiovascular disease, and aging and obesity are reported as common factors in chronic disease. However, there have been only a few studies on the associations of POPs with age and body mass index (BMI) in Korea. Therefore, we analyzed the associations of serum POPs levels with age and BMI in Korea. Methods: This cross-sectional study includes 444 subjects (253 men and 191 women) from the Korean Cancer Prevention Study-II (2004-2011). Serum levels of 33 polychlorinated biphenyls (PCBs) and 19 organochlorine pesticides (OCPs) were measured by a gas chromatographer (Agilent 6890) coupled to high resolution mass spectrometer (JEOL JMS-800D). Results: Concentrations of PCB 153 (men: 12.26 ng/g lipid, women: 10.50 ng/g lipid) and p,p'-DDE (men: 94.66 ng/g lipid, women: 96.66 ng/g lipid) were the highest among serum PCBs and OCPs, respectively. PCBs and OCPs were significantly positively correlated with age in both sexes. After adjustment for age, non-dioxin like PCBs were significantly negatively correlated with body mass in women. However, cis-heptachlor epoxide was significantly positively correlated with body mass index in both sexes. When analyzed by sex, stronger associations were shown between POPs and age in men and POPs and BMI in women. Conclusion: These results may provide baseline data for the study of POPs and for the health management field in Korea.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.299-304
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• 2002

Volatile flavor compounds in the headspace of swiss cheese whey protein concentrate (WPC) were analyzed by dynamic headspace analyzer, gas chromatography, and mass spectrometer. Sixty one compounds were detected from the headspace of dry WPC and 23 compounds from the headspace of an aqueous solution of WPC. The major components were propanol, hexanal, 2-butanone, 2-pentanone, 2,3-butanedion, 2-propanol, acetic acid, dimethyl disulfide and benzothiazole. An external dynamic headspace sampler, devised for this study, effectively collected volatiles from the headspace of dry WPC and aqueous WPC solutions.

• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.160-164
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• 2007

Aminofuroxan derivatives 3 and 4 were prepared by the reaction of chlorofuroxan 2 with butyl and benzyl amines, respectively. E-beam mediated fragmentation of aminofuroxans 3, 4 in mass spectrometer was analyzed in a view of the corresponding alkyne formation.