• Journal of Ginseng Research
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• 제21권3호
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• pp.214-218
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• 1997

New simple methods for the Isolation of sesquiterpenes from Panax ginseng were developed. First, volatile compounds were isolated by simultaneous distillation and extraction (SDE) with 30% methanol and $\alpha$-hexane instead of water and ethyl ether/pentane (1:1). Secondly, head space volatiles in U-shaped tube at 7$0^{\circ}C$ were passed through C18 Sep-Pak by nitrogen gas streaming and the adsorbed volatiles were fluted by $\alpha$-hexane. TLC analysis showed that the volatile concentrates consisted mainly of terpenes when colored by vanillin-sulfuric and. GC/MS data revealed that approximately 30 sesquiterpenes of molecular weight 204 occupied 81.1% or more of the volatile concentrates isolated by those two newly developed methods. Among these, alloaromadendrene, germacrene B, isocaryophyllene, $\alpha$-neoclovene, ${\gamma}$-muurolene, $\beta$-panaslnsene, and $\alpha$-humulene were identified as being major sesqulterpenes by authentic samples or literatme search Key words : Panax ginseng, volatile compound, sesquiterpene, isolation, new method, GC/MS.

• 한국식품영양학회지
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• 제12권2호
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• pp.119-123
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• 1999

Test of the optimum condition of solid phase micro extraction(SPME) was performed by use of 5 vol-atile components in dilute aqueous solution. Volatile components of Sancho(Zanthoxylum schinifolium) were isolated by SPME method and were analyzed by GC/MSD and compared with volatile compone-nts isolated by simultaneous distillation extraction (SDE) method. Total 31 components were identified by comparing gas chromatography retention time and mass spectral data. The major compounds were limonene geranyl acetate $\beta$-phellandrene phellandral mycene linalool rose oxide caproic acid and caprylic acid SPME sampling procedure was found to be a good method for qualitative analysis of the volatile components.

• Korean Chemical Engineering Research
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• 제57권6호
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• pp.883-890
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• 2019

Two-phase flow near the wellbore in volatile oil reservoirs causes complications in well test analysis. In this study, the flow behavior of volatile oil reservoirs below the bubble-point pressure and the potential of radial composite model for interpretation of two-phase well test in volatile oil reservoirs was investigated. A radial composite model was used for two-phase well test analysis. A new procedure was developed to interpret well test data and estimate the radius of the two-phase region. The changes in fluid composition near the wellbore during drawdown test were found to increase the saturation pressure, which affects the saturation profile during build-up. Well test results showed that the radial composite method is a powerful tool for well test characterization and estimation of reservoir parameters. The proposed procedure was able to estimate the reservoir parameters and radius of the two-phase region with acceptable accuracy.

• 한국식품영양과학회지
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• 제29권5호
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• pp.965-967
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• 2000

An on-line FIA system in place of traditional Conway method was used for quicker and simpler analysis of volatile basic nitrogen of pork. The on-line system was developed by connecting an FIA apparatus with an ammonia electrode as a detector to a personal computer. The data from Conway method and from the on-line FIA system were in good agreement and the correlation coefficient was 0.981. One sample could be analyzed in about 4 min.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권1호
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• pp.32-39
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• 2008

Tunnel oxide of non-volatile memory (NVM) devices would be very difficult to downscale if ten-year data retention were still needed. This requirement limits further improvement of device performance in terms of programming speed and operating voltages. Consequently, for low-power applications with Fowler-Nordheim programming such as NAND, program and erase voltages are essentially sustained at unacceptably high levels. A promising solution for tunnel oxide scaling is tunnel barrier engineering (TBE), which uses multiple dielectric stacks to enhance field-sensitivity. This allows for shorter writing/erasing times and/or lower operating voltages than single $SiO_2$ tunnel oxide without altering the ten-year data retention constraint. In this paper, two approaches for tunnel barrier engineering are compared: the crested barrier and variable oxide thickness. Key results of TBE and its applications for NVM are also addressed.

• Environmental Engineering Research
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• 제17권2호
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• pp.103-110
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• 2012

This study was performed mainly to examine whether a city with a metal industrial presence presents different characteristics in ambient volatile organic compound (VOC) concentrations compared to residential (RES) and commercial/residential combined (CRC) areas of another city by using long-term monitoring data (from January 2006 to February 2009). For most target VOCs, ambient concentrations in the metal-industrialized city were lower than for the RES and CRC areas. Aromatic compounds were the predominant VOC groups for the metal industry city as well as for other land uses. The ambient concentrations of aromatic VOCs were higher in the winter and spring seasons than in the summer and fall seasons, whereas those of chlorinated VOCs did not show any distinctive variations. In addition, higher concentrations were observed during daytime hours. The correlations between the ambient target compounds were statistically significant, except for the correlation between benzene and ozone.

• 한국입자에어로졸학회지
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• 제7권1호
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• pp.31-44
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• 2011

The hourly volatile organic compounds(VOCs) concentrations between 2005 and 2008 at Bulgwang photochemical assessment monitoring station were investigated to establish a method for quality assurance and quality control(QA/QC) procedure. Systematic error, erratic error, and random error, which was manifested by outlier and highly fluctuated data, were checked and removed. About 17.3% of the raw data were excluded according to the proposed QA/QC procedure. After QA/QC, relative standard deviation for representing 15 species concentrations decreased from 94.7-548.0% to 63.4-125.8%, implying the QA/QC procedure is proper. For further evaluation about the adequacy of QA/QC procedure, principal components analysis(PCA) was carried out. When the data after QA/QC procedure was used for PCA, the extracted principal components were different from the result from the raw data and could logically explain the major emission sources(gasoline vapor, vehicle exhaust, and solvent usage). The QA/QC procedure based on the concept of errors is inferred to proper to be applied on VOCs. However, an additional QA/QC step considering the relationship between species in the atmosphere needs to be further considered.

• Preventive Nutrition and Food Science
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• 제8권4호
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• pp.315-320
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• 2003

Headspace volatile compounds of oxidized fish oil were analyzed by the combination of hexane solvent or solid phase microextraction, gas chromatography and mass selective detector. The optimum condition of headspace analysis by hexane trapping was 23 min absorption time, 96$^{\circ}C$ sample temperature and 20 mL/min air flow rate. The numbers of volatile compounds identified by solvent trapping and SPME were 35 and 14, respectively. Groups having the largest amount and many kinds were hydrocarbons and aldehydes, respectively. The numbers of aldehydes were 15 and 6 for solvent trap and SPME, respectively. These basic data could be used as indicators for the quality changes of fish oil.

• 한국미생물·생명공학회지
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• 제27권6호
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• pp.491-499
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• 1999

A great variety of the volatile metabolic by-products was formed in yeast cell during alcohol fermentation. The seibel grape (Vitis labrasca) which was grown in the Southern Korea used for wines. The objective of this research was to identify the volatile flavor compounds during alcohol fermentation and aging at 12$^{\circ}C$. saccharomyces cerevisiae and Schizosaccharomyces pombe were inoculated and fermented in seibel grape must. The volatile flavor compounds of logarithmic, stationary and death phases were extracted, concentrated and identified by gas chromatography/mass spectrometer (GC/MS). The volatile flavor compounds were determined by a Hewlett-Packard 5890 II Plus GC which was equipped with Supelcowax 10 fused silica capillary column (60m$\times$0.32mm$\times$0.25${\mu}{\textrm}{m}$ film thickness) wall coated with polyethyleneglycerol. The scan detection method allowed the comparison of the spectrum from the chromatogram of volatile flavor compounds to those in data Wileynbs base library. Among the volatile compounds collected by ether-hexane extraction method, the evolution of 20 main compounds, such as 9 esters (ethyl butyrate, isoamyl acetate, ethyl caproate, n-hexyl acetate, ethl caprylate, ethyl caprate, diethy succinate, ethyl hexadecanoate, 2-pheneethyl acetate), 4 alcohols (3-methyl-1-butanol, 1-hexanol, 1-heptanol, benzoethanol), 4 ketones and acids (2-octanone, caproic acid, caprylic acid, capric acid), 2 furan and phenol (2,6-bis(1,1-dimethyl ethyl)phenol, 2,3-dihydrobenzofuran) were observed during alcohol fermentation and aging. The production of the esters during alcohol fermentation with S. cerevisiae was higher than those of Sch. pombe. The sensory scores of the aged wine samples in aroma, taste and overall acceptability were not significantly different(p<0.05).

• 한국컴퓨터정보학회논문지
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• 제17권11호
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• pp.101-105
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• 2012

최근 스마트폰의 급격한 보급으로 개인정보 침해사고 및 프라이버시 침해를 통한 여러 가지 사회문제가 급속도로 증가하고 있으며, 이에 따라 개인 정보보호를 위한 다양한 연구 및 기술 개발이 이루어지고 있다. 개인의 모든 정보가 거의 들어 있다고 해도 과언이 아닌 스마트폰의 정보유출은 우리의 일상에서 쉽고 빈번하게 발생할 수 있는데, 포렌식 분석 툴을 이용하여 증거를 수집하거나 분석하기란 쉽지 않은 일이다. 현재 안드로이드 포렌식 연구는 비휘발성 메모리로부터 데이터를 수집하여 분석하는 기법에 집중되어 왔으며, 휘발성 데이터에 대한 연구는 미미한 실정이다. 안드로이드 로그는 휘발성 저장매체로부터 수집될 수 있는 휘발성 데이터이다. 안드로이드 로그는 안드로이드 시스템에서부터 애플리케이션에 이르기까지 최근의 모든 구동내역과 관련한 기록이 로그로 저장되기 때문에 안드로이드폰 사용을 추적할 수 있는 자료로 활용이 충분하다. 본 논문에서는 포렌식 분석 툴을 이용하지 않고 로그를 필터링하여 개인의 정보 유출 유무를 판단하여 대응할 수 있는 방법을 제시한다.