• 한국환경과학회지
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• 제19권7호
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• pp.829-841
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• 2010

The estimation of a biogenic volatile organic compound (BVOC, especially isoprene) and the influence of isoprene emissions on ozone concentrations in the Greater Busan Area (GBA) were carried out based on a numerical modeling approach during a high ozone episode. The BVOC emissions were estimated using a biogenic emission information system (BEIS v3.14) with vegetation data provided by the forest geographical information system (FGIS), land use data provided by the environmental geographical information system (EGIS), and meteorological data simulated by the MM5. Ozone simulation was performed by two sets of simulation scenarios: (1) without (CASE1) and (2) with isoprene emissions (CASE2). The isoprene emission (82 ton $day^{-1}$) in the GBA was estimated to be the most dominant BVOC followed by methanol (56) and carbon monoxide (28). Largest impacts of isoprene emissions on the ozone concentrations (CASE2-CASE1) were predicted to be about 4 ppb in inland locations where a high isoprene was emitted and to be about 2 ppb in the downwind and/or convergence regions of wind due to both the photochemical reaction of ozone precursors (e.g., high isoprene emissions) and meteorological conditions (e.g., local transport).

• 한국환경과학회지
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• 제21권6호
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• pp.713-724
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• 2012

Emission rates of biogenic hydrocarbon emitted from broad-leaved trees grown at Jeju Island were estimated using a dynamic enclosure method. Leaf temperature, PAR and relative humidity were monitored during the sampling time. The emission rates of isoprene and monoterpene were measured for five plants(Carpinus laxiflora, Quercus serrata, Styrax japonicus, Quercus acutissima, Quercus crispula) during the sampling period at the Halla mountain sites. Among five tree species, the highest isoprene emission rate of 10.60 ${\mu}g\;gdw^{-1}hr^{-1}$ was observed for Quercus serrata. The seasonal emission rates were the highest during summer and the emission of isoprene was highly affected by light and temperature variations. The highest emission rate of isoprene was occurred between 13:00 and 14:00, but isoprene was not emitted in nighttime because of the absence of light.

• 청정기술
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• 제10권3호
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• pp.169-176
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• 2004

촉진 수송 분리 막은 $Ag^+$ 이온과 올레핀 사이에서 ${\pi}$-complexation을 형성하고, 촉진 수송 현상에 의하여 올레핀을 선택적으로 분리한다. 본 연구에서는 Isoprene/n-pentane 분리를 위해 Sulfonated poly(ether ether)ketone (SPEEK)-$AgNO_3$로 이루어진 촉진 수송 분리 막을 제조하여 실험하였다. 이 분리 막은 isoprene의 좋은 선택도와 투과도를 나타내었고 장시간 동안 안정하게 분리 막의 성능을 유지하였다. SPEEK는 다양한 합성 조건에 따라서 degree of sulfonation (DS)가 많은 차이를 나타냈고, 1H NMR spectroscopy를 사용하여 제조된 SPEEK의 DS를 측정하였다. 이렇게 제조된 SPEEK를 이용한 분리 막의 선택도나 투과도와 같은 성능은 SPEEK의 DS에 의해 영향을 받았다. SPEEK의 DS가 높을수록, n-pentane에 대한 isoprene의 선택도는 최대 850 ~ 900까지 증가하였고, 또한 막의 안정성 역시 100시간 이상 유지되었다.

• Journal of Microbiology and Biotechnology
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• 제29권10호
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• pp.1656-1664
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• 2019

Isoprene has the potential to replace some petroleum-based chemicals and can be produced through biological systems using renewable carbon sources. Ralstonia eutropha can produce value-added compounds, including intracellular polyhydroxyalkanoate (PHA) through fatty acid and lipid metabolism. In the present study, we engineered strains of R. eutropha H16 and examined the strains for isoprene production. We optimized codons of all the genes involved in isoprene synthesis by the mevalonate pathway and manipulated the promoter regions using pLac and pJ5 elements. Our results showed that isoprene productivity was higher using the J5 promoter ($1.9{\pm}0.24{\mu}g/l$) than when using the lac promoter ($1.5{\pm}0.2{\mu}g/l$). Additionally, the use of three J5 promoters was more efficient ($3.8{\pm}0.18{\mu}g/l$) for isoprene production than a one-promoter system, and could be scaled up to a 5-L batch-cultivation from a T-flask culture. Although the isoprene yield obtained in our study was insufficient to meet industrial demands, our study, for the first time, shows that R. eutropha can be modified for efficient isoprene production and lays the foundation for further optimization of the fermentation process.

• Elastomers and Composites
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• 제44권1호
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• pp.55-62
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• 2009

본 논문에서는 nitroxide 매개 리빙라디칼 중합법을 이용한 isoprene의 중합 특성에 관하여 연구하였다. 중합 첨가제로 acetol이 첨가된 경우, 생성되는 고분자의 분자량이 전환율에 따라 직선적으로 증가하고, 제조된 고분자의 분자량 분포값이 1.5 이하의 값을 보임으로써, 성공적인 리빙라디칼 중합이 이루어졌음을 알 수 있었다. 제조된 polyisoprene은 약 22%의 3, 4구조, 약 30%의 1, 4-cis구조, 약 48%의 1, 4-trans 구조로 구성되어 있었다. 중합은 145 $^{circ}C$에서 최선의 결과를 보였으며, 이보다 낮은 온도에서는 진행되지 않았다. Nitroxide의 경우, non-cyclic nitroxide인 di-tert-butyl nitroxide (DTBN)의 경우 리빙라디칼 중합을 매개하지 못하였으나, 2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (TEMPO)와 4-oxo-2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (oxoTEMPO)의 경우 성공적으로 리빙라디칼 중합을 매개하였다. 그러나, 주어진 중합조건 내에서 일부 isoprene은 Diels-Alder 이량화 반응(dimerization)에 의하여 고분자가 아닌 limonene 등으로 전환되는 것으로 관찰되었다. 주어진 중합조건하에서 isoprene의 자동열개시 반응도 가능하였으나, 별도의 중합개시제를 사용할 경우 그 정도는 무시할 수 있을 정도의 양인 것으로 판단되었다.

• 한국산업보건학회지
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• 제21권2호
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• pp.73-81
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• 2011

The purpose of this study was to obtain scientific information regarding classification and health hazards that may result from a 13 weeks inhalation exposure of isoprene in Sprague-Dawley (SD) rats. The testing method was conducted in accordance with OECD guidelines for the testing of chemicals No. 413. The Rats were divided into 4 groups (10 male and 10 female rats in each group) and exposed to 0, 360, 1,620, 7,300 ppm isoprene in each exposure chamber for 6 h/day, 5 days/week, for 13 weeks. As a result, there were no mortality or abnormality during the period of study and did not show any significant changes of body weight. There were no dose response changes in urinalysis, hematological and serum biochemical value examination. Relative organ weight was increased significantly the right kidney in 7,300 ppm group of male rats. In female rats, relative organ weight of the left kidney and the both lungs in 1,620 ppm group and the left lung and the both kidneys in 7,300 ppm group were increased significantly. But the histopathological findings did not reveal any exposure-related changes. According to the above results, the no observable adverse effect level (NOAEL) of isoprene was 7,300 ppm (20.3 mg/L) in both male and female rats. In conclusion, Isoprene was not classified specific target organ toxicity of the 'Standard for Classification and Labeling of Chemical Substance and Material Safety Data Sheet' (Ministry of Employment and Labor, 2009).

• 분석과학
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• 제27권6호
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• pp.357-363
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• 2014

아이소프렌은 자연기원의 휘발성 유기화합물 (BVOCs) 중의 하나로 대류권 오존 생성 및 포름알데히드의 근원으로 알려져 있다. 또한, 아이소프렌은 호흡가스에 포함된 미량 성분으로 폐암과 같은 질병의 진단마커로 사용되기도 하기 때문에 대기 중 아이소프렌의 정확한 측정을 위해 신뢰성 있는 가스 표준물질이 요구되고 있다. 본 연구에서는 아이소프렌 측정용 일차표준가스의 개발을 위해 중량법에 의한 제조 및 특성평가를 수행하였다. 독립적으로 제조한 일차표준가스들의 농도를 가스크로마토그래프-불꽃이온화검출기(GC-FID)로 비교하여 0.01%의 순도를 포함한 중량법에 의한 제조 불확도와 0.08% 수준의 제조 재현성을 확인하였다. 제조한 일차표준가스는 14개월간 동안 1.3% 수준의 안정성을 보였다. 원료의 순도, 질량측정(질량값), 제조 재현성, 흡착성 및 장기 안정성을 모두 고려하여 결정한 $10{\mu}mol/mol$ 수준 아이소프렌 일차표준가스 인증값의 상대 확장불확도는 2.8%(95%의 신뢰수준, k=1.96)이었다.

• 한국대기환경학회지
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• 제22권6호
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• pp.791-798
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• 2006

In order to investigate the NVOC (Natural Volatile Organic Compound) emissions from White Oak, the emission rates of isoprene were measured according to season, weather conditions, and the age of the tree. The analysis of seasonal emission rates showed that the emission rates were the highest during summer followed by spring and fall. The emission rates during summer were found to be nearly 8 times greater than those during fall. In addition, it was observed that the emission rates of isoprene depends on PAR and temperature. Moreover, the effect of age on the emission rates was studied, and the White Oak in the age range of $21{\sim}30$ had higher emission rates than that in the range of $41{\sim}50$. Accordingly, the current result indicates that the isoprene emissions are affected by both meteorological parameter and the age of a tree.

• 한국환경보건학회지
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• 제35권6호
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• pp.532-537
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• 2009

The tropospheric ozone production mechanism for the gas phase additive oxidation reaction of hydroxyl radical (OH) with isoprene (2-methyl-1,3-butadiene) has been studied using cavity ring-down spectroscopy (CRDS) at total pressure of 50 Torr and 298 K. The applicability of CRDS was confirmed by monitoring the shorter (~4%) ringdown time in the presence of hydroxyl radical than the ring-down time without the photolysis of hydrogen peroxide. The reaction rate constant, $(9.8{\pm}0.1){\times}10^{-11}molecule^{-1}cm^3s^{-1}$, for the addition of OH to isoprene is in good agreement with previous studies. In the presence of $O_2$ and NO, hydroxyl radical cycling has been monitored and the simulation using the recommended elementary reaction rate constants as the basis to OH cycling curve gives reasonable fit to the data.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2004년도 춘계학술대회 논문집
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• pp.272-273
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• 2004