• Journal of Korean Society for Atmospheric Environment
• /
• 제17권E3호
• /
• pp.101-107
• /
• 2001

Source profiles were developed for a total of 45 volatile organic compounds (VOC) that can be emitted from gasoline evaporation. The gasoline samples of five major brands (for each season) were blended on the basis of the market share in Seoul area and analyzed by a GC-MS/FID system. In addition, we calculated gasoline evaporative compositions using the Raoult's law from the liquid gasoline compositions. The measured and estimated gasoline vapor compositions agree well each other. As a group, alkanes are the most abundant in the gasoline vapors profiles (77.4% on average), followed by alkenes (19.1%), and aromatics (1.7%). As a specie in gasoline vapor, i-pentane is the most abundant, followed by n-butane, n-pentane, i-butane, trans-and cis-2-butenes, 2-methyl-2-butene, and trans-and cis-2-pentenes . It was also seen that aromatic content was much lower in the vapor phase compositions. From the comparison between experimental and calculated compositions, we identified the fact that once the gasoline vapor composition is reliably constructed entirely from the measured gasoline composition and the Raoult's law calculations, the need for doing separate chemical analyses of the gasoline vapor can be reduced.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.237.1-237.1
• /
• 2016

Electrical properties of graphene-based field effect transistors (G-FETs) can be degraded in ambient conditions owing to physisorbed oxygen or water molecules on the graphene surface. Passivation technique is one of a fascinating strategy for fabrication of G-FETs, which allows to sustain electrical properties of graphene in the long term without disrupting its inherent properties: transparency, flexibility and thinness. Ironically, despite its importance in producing high performance graphene devices, this method has been much less studied compared to patterning or device fabrication processes. Here we report a novel surface passivation method by using atomically thin self-assembled alkane layers such as C18- NH2, C18-Br and C36 to prevent unintentional doping effects that can suppress the degradation of electrical properties. In each passivated device, we observe a shift in charge neutral point to near zero gate voltage and it maintains the device performance for 1 year. In addition, the fabricated PG-FETs on a plastic substrate with ion-gel gate dielectrics exhibit not only mechanical flexibility but also long-term stability in ambient conditions. Therefore, we believe that these highly transparent and ultra-thin passivation layers can become a promising candidate in a wide range of graphene based electronic applications.

• 한국대기환경학회지
• /
• 제19권4호
• /
• pp.387-396
• /
• 2003

A field study was conducted during the summer time of 2002 to determine compositions of volatile organic compounds (VOCs) emitted from vehicles and to develop source emission profiles that is applied to CMB model to estimate the source contribution of certain area. Source emission profile is widely used for the estimation of source contribution by the chemical mass balance model and have to be developed applicable for the target area of estimation. This study was aimed to develop source emission profile and estimation of source contribution of VOCs after application of the chemical mass balance (CMB) receptor model. After considering the emission inventory and other research results for the VOCs in Seoul, Korea, the sources like vehicle emission (tunnel), gas station (gasoline, diesel), solvent usage (painting operation, dry cleaning, graphic art), and gas fuels were selected for the major VOCs sources. Furthermore, ambient air samples were simultaneously collected from 09:00 to 11:00 for four days at eight different official air quality monitoring sites as receptors in Seoul during summer of 2001. Source samples were collected by canisters, and then about seventy volatile organic compounds were analyzed by gas chromatography with flame ionization detector (GC/FID). Based on both the developed source profiles and the database of the receptors, CMB model was intensively applied to estimate mass contribution of VOCs sources. Examining the source profile from the vehicle, the portion of alkanes of VOCs was highest, and then the portion of aromatics such toluene, m/p-xylene were followed. In case of gas fuel. they have their own components; the content of butane, propane, ethane was higher than any other component according to the fuel usage. The average of the source apportionment on VOCs for 8 sites showed that the major sources were vehicle emission and gas fuels. The vehicle emission source was revealed as having the highest contribution with an average of 49.6%, and followed by solvent with 21.3%, gas fuel with 16.1%, gasoline with 13.1%.

• 한국대기환경학회지
• /
• 제25권5호
• /
• pp.420-431
• /
• 2009

Characteristics and advantages of the thermal desorption-comprehensive two dimensional gas chromatography-time of flight mass spectrometry (TD-GCxGC-TOFMS) were discussed and the organic compound's analysis result was shown for the ambient $PM_{2.5}$ sample collected in Seoul, Korea. Over 10,000 individual organic compounds were separated from about $70{\mu}g$ of aerosols in a single procedure with no sample pre-treatment. Among them, around 300 compounds were identified and classified based on the mass fragmentation patterns and GCxGC retention times. Several aliphatic compounds groups such as alkanes, alkenes, cycloalkanes, alkanoic acids, and alkan-2-ones were identified as well as 72 PAH compounds including alkyl substituted compounds and 8 hopanes. In Seoul aerosol, numerous oxidized aromatic compounds including major components of secondary organic aerosols were observed. The inventory of organic compounds in $PM_{2.5}$ of Seoul, Korea suggested that organic aerosol were constituted by the compounds of primary source emission as well as the formation of secondary organic aerosols.

• 한국작물학회지
• /
• 제51권spc1호
• /
• pp.297-303
• /
• 2006

Cuticular waxes on tea (Camellia sinensis L.) loaves consisted mainly of alkanes, fatty acids, primary alcohols, triterpenes, and a group of unknown compounds, dominated by primary alcohols and triterpenes. Tea tree accessions used in this study were M-1, M-2, Sakimidori, and Yabukita. For all accessions, the alkane, fatty acid, and primary alcohol constituents consisted of a homologues series, and the major constituents of primary alcohol class were the C28 and C30 homologues. Triterpenes consisted of friedelin, $\beta-amyrin$, and three unidentified ones and friedelin was the most abundant. Leaf area and the total amounts of cuticular waxes per leaf increased with lower leaf position from the apical bud in Yabukita variety. With different leaf position, total wax amount per unit leaf area on the youngest leaves of P1 (the uppermost leaf position) showed the largest amount $(12.80{\mu}g/cm^2)$, and on mature loaves of P2 to P6 ranged from 7.08 to $7.77{\mu}g/cm^2$, and then on the oldest loaves of P7 (the lowest leaf position) remained at an increased level $(17.53{\mu}g/cm^2)$. During leaf development (lower leaf position), the amount of primary alcohols decreased from P1 to P6 and increased at P7, whereas that of triterpenes increased from P1 to P7. The percentage of each wax class in the total wax amount occurred a decrease in primary alcohol and an increase in triterpene, with leaf age.

• 공업화학
• /
• 제19권1호
• /
• pp.59-65
• /
• 2008

비이온 계면활성제 $C_{12}E_8$ 마이셀에 의한 이성분 탄화수소 오일 혼합물 시스템의 가용화도(equilibrium solubilization capacity)를 $23^{\circ}C$에서 기체 크로마토그래피(GC)를 이용하여 측정하였다. 단일 성분의 탄화수소 오일 가용화도는 탄화수소 오일의 탄소수(ACN)가 증가함에 따라 거의 선형적으로 감소하였다. 한편 탄화수소 오일의 이성분 시스템은 사용한 두 탄화수소 오일의 탄소수(alkane carbon number, ACN) 차이에 따라 선택적 가용화 혹은 비선택적 가용화 경향을 나타내었다. 본 연구에서 가용화도 실험을 수행한 n-octane/n-nonane, n-nonane/n-decane과 n-decane/n-undecane 혼합물 시스템과 같이 이성분 탄화수소 혼합물의 탄소수 차이가 1인 경우에는 비선택적(non-selective) 가용화 경향을 나타내었다. 반면에 n-octane/n-decane과 n-octane/n-undecane 혼합물 시스템과 같이 탄소수 차이가 1보다 큰 경우에는 선택적(selective) 가용화 경향을 나타내었다.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
• /
• pp.66-69
• /
• 2002

In this work, cost effective venting is considered by comparing flow rates of 5$m\ell$/min, 10$m\ell$/min, and 20$m\ell$/min. Studies were performed on a soil artificially contaminated with diesel oil (the initial TPH(Total Petroleum Hydrocarbon) concentration of 7098mg/kg), and nutrient condition was C:N:P rate of 100:10:1. The soil has a sandy texture with pH of 6.8, 2.16 ~2.38% organic matter, a total porosity of 47~52% and field capacity 16.2~ 17.2%. The column experiments was made of glass column of 60cm length and 10cm I.D. at controlled temperature of 2$0^{\circ}C$($\pm$2.5$^{\circ}C$). The efficiency of continuous flow rate of 5, 10 and 20$m\ell$/min resulted in separately 61.3%, 58.1%, and 55% reduction of initial TPH concentration(7098mg/kg). Hydrocarbon utilizing microbial count and dehydrogenase activity in air flow of 5$m\ell$/min were higher than those of the others. The first order degradation rate of n-alkanes ranging from C10 to C28 was higher than that of pristane and phytane as isoprenoids. The $C_{17}$/pristane and $C_{18}$phytane ratios for monitoring the degree of biodegradation were useful only during the early stages of oil degradation. Degradation contributed from about 89% to 93% of TPH removal. Volatilization loss of diesel oil in contaminated soil was about 7% to 11%, which was significantly small compared to degradation.n.

• 한국해양학회지:바다
• /
• 제5권4호
• /
• pp.374-380
• /
• 2000

제주-대한해협중 소흑산도에서 부산앞 대마도부근 까지의 제주도 이북의 대륙붕 해역 (33$^{\circ}$30'${\sim}$34$^{\circ}$N 125$^{\circ}$${\sim}$128$^{\circ}$E) 용존탄화수소의 분포와 성인을 조사하였다. 표층 해수중 용존탄화수소 총함량의 시 ${\cdot}$ 공간적 변이는 10배 이상이 대체로 연안에서 높고 외해에서 낮으며, 총함량은 가을에 봄보다 높다. 탄화수소의 성인을 n-alkanes과 pristane함량을 기준으로 보면 해수중 용존 탄화수소는 1998년 4월의 경우, 황해남부(125$^{\circ}$E) 해역에서는 식물플랑크톤기원 및 석유기원 탄화수소가 우세하고, 남해에서는 육상기원과 석유기원이 우세하다. 그리고 1998년 9월에는 남해에 식물플랑크톤과 석유기원이 우세하게 나타났다.

• 한국토양환경학회지
• /
• 제5권1호
• /
• pp.85-96
• /
• 2000

본 연구의 목적은 수분함량 및 온도변화가 석유계탄화수소의 분해에 미치는 영향을 살펴보는 것이었다. 연구에 사용된 토양은 사질양토였으며 대상오염물질은 디젤오일이었다. 디젤오일의 초기오염농도는 건조질량기준으로 10,000mgTPH/kg이었다. 수분함량은 토양 수분보유능력의 50%, 70%그리고 90%로 조절하였으며 온도는 $5^{\circ}C$, $10^{\circ}C$, $20^{\circ}C$, 그리고 $30^{\circ}C$로 변화시켰다. 석유계 총탄화수소의 분해는 수분함량이 수분보유능력의 50%와 70%에서 활발하게 일어났다. 온도는 10~3$0^{\circ}C$에서 석유계 총탄화수소의 분해가 활발하였으며 5$^{\circ}C$에서는 상대적으로 분해속도가 느리게 나타났다. 노르말알칸류의 분해속도는 석유계 총탄화수소에 비하여 약 2배 정도 빠르게 나타났다. 휘발에 의하여 손실된 석유계 총탄화수소는 초기 농도의 약 2% 내외였다. 대조실험으로서 공기공급을 하지 않은 경우와 biocide로 $HgCl_2$를 첨가한 경우에 석유계 총탄화수소의 분해가 미미하여 석유계 총탄화수소가 호기성조건하에서 생물학적 반응에 의하여 분해되었음을 보여주었다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제21권5호
• /
• pp.8-15
• /
• 2016

Bioremediation, which uses microbes to degrade most organic pollutants in soil and groundwater, can be used in solving environmental issues in various polluted sites. In this research, a wind-driven bioventing system is built to degrade about 20,000 mg/kg of high concentration diesel pollutants in soil-pollution mode. The wind-driven bioventing test was proceeded by the bioaugmentation method, and the indigenous microbes used were Bacillus cereus, Achromobacter xylosoxidans, and Pseudomonas putida. The phenomenon of two-stage diesel degradation of different rates was noted in the test. In order to interpret the results of the mode test, three microbes were used to degrade diesel pollutants of same high concentration in separated aerated batch-mixing vessels. The data derived thereof was input into the Haldane equation and calculated by non-linear regression analysis and trial-and-error methods to establish the kinetic parameters of these three microbes in bioventing diesel degradation. The results show that in the derivation of μ_m (maximum specific growth rate) in biodegradation kinetics parameters, K_s (half-saturation constant) for diesel substance affinity, and K_i (inhibition coefficient) for the adaptability of high concentration diesel degradation. The K_s is the lowest in the trend of the first stage degradation of Bacillus cereus in a high diesel concentration, whereas K_i is the highest, denoting that Bacillus cereus has the best adaptability in a high diesel concentration and is the most efficient in diesel substance affinity. All three microbes have a degradation rate of over 50% with regards to Pristane and Phytane, which are branched alkanes and the most important biological markers.