• Journal of Microbiology and Biotechnology
• /
• 제10권5호
• /
• pp.724-727
• /
• 2000

A Phenanthrene-degrading bacterium, Strain 1-21 was isolated from oil-contaminated soil. This strain was a Gram-negative, aerobic, and rod-shaped bacterium, and exhibited a 99% sequence similarity of 16S rDNA to that of Sphingomonas subarctica. The major cellular fatty acid was a summed feature 7(18:1 w7c, 18:1 w9t, 18:1 s12t), which is a characteristic of the Sphingomonas species. When 200 and 1,000 ppm of phenanthrene was added as the sole carbon source, Strain 1-21 degraded 98% and 67% after 10 days of incubation, respectively. Futhermore, this strain was also able to utilized naphthalene and fluorene as sole carbon and energy sources.

• 한국식품영양학회지
• /
• 제12권4호
• /
• pp.415-420
• /
• 1999

Petal of Azalea(Rhododendron mucronulatum Turcz) was incubated with Gokja at 3$0^{\circ}C$ for seven days and the essential oil components of petal of Azalea before and after incubated were analyzed using a GC/MSD. Ten or more essential oil components including n-heneicosane n-tricosane n-tetreacosane n-pentacosane n-heptacosane n-nonacosane and n-hentriacontane were identified from the petal of Azal-ea before incubated while oxygen-containng compounds including (E)-heptenal 2-ethoxy-1 -hexanol n-hexadecanoic acid methyl ester 9, 12-octadecadienoic acid methyl ester 9,12,15-octadecatrienoic acid methyl ester, n-octadecanoic acid methyl ester n-eicosanoic acid methyl ester and 9-docosaenoic acid methyl ester as well as n-alkanes such as n-tricosane that n-pentacosane were identified from the petal of Azalea after incubated. These results suggest that n-alkanes in petal of Azalea might be degraded and some oxygen-containing compounds such as aldehyde, esters and /or acids might be produced when pet-al of Azalea is incubated with Gokja.

• Advances in nano research
• /
• 제15권4호
• /
• pp.305-313
• /
• 2023

This study is aimed to investigate the electrically conductive properties of epoxy nanocomposites exposed to an acidic environment under various mechanical loads. For simultaneous assessment of the acidic environment and mechanical load on the electrical conductivity of the samples, the samples with and without carbon nanotubes were exposed to the acidic environment under three different loading conditions for 20 days. Then, the aged samples' strength and flexural stiffness degradation under crude oil and bending stress were measured using a three-point flexural test. The aged samples in the acidic environment and under 80 percent of their intact ultimate strength revealed a 9% and 26% reduction of their electrical conductivity for samples with and without CNTs, respectively. The presence of nanoparticles declined flexural stiffness by about 16.39%. Scanning electron microscopy (SEM) images of the specimen were used to evaluate the dispersion quality of CNTs. The results of this study can be exploited in constructing conductive composite electrodes to be used in petroleum environments such as crude oil electrostatic tanks.

• 폴리머
• /
• 제28권4호
• /
• pp.291-297
• /
• 2004

수용성 키토산의 농도와 가교제 (글루타알데히드)의 양을 변화시키면서 미네랄오일 내에서 키토산용액의 유화법에 의해 수용성 키토산 미세구를 제조하였다. 그러고 약물이 봉입되어진 수용성 키토산 미세구의 분해에 따른 형태의 변화, 약물의 봉입효율, 약물 방출 거동과 같은 물리화학적 특성을 규명하였다. Norfloxacion 이 봉입된 수용성 키토산 미세구는 표면의 약물에 의해 나타나는 과량의 약물 방출이 없는 높은 약물 봉입 함량을 보였다. 표면에 약물이 존재하지 않음을 선 회절 분석으로 확인하였다. 수용성 키토산 미세구의 분해 특성과 약물방출 거동을 관찰한 결과 가교제의 양이 약물의 봉입량, 방출, 그리고 분해에 중요한 역할을 하는 것을 확인하였다. 수용성 키토산 미세구는 가교제의 양이 증가함에 따라 분해속도가 느렸으며, 이와 동시에 약물이 천천히 방출되었음을 확인하였다.

• 대한기계학회논문집A
• /
• 제20권4호
• /
• pp.1123-1132
• /
• 1996

It has been reported that high temperature structural components represent the phenomenon of material degradation according to a long term service under high temperature and pressure. Especially, fossile power plant components using the fossil fuel and heavy oil are affected by dewpoint corrosion of $H_2SO_4$produced during a combustion. Therefore, the service materials subjected to high temperature and pressure may occur the stress corrosion cracking. The object of this paper is to investigate SCC susceptibility according to the material degradation of the high temperature structural materials in dewpoint corrosive environment-$H_2SO_4$.The obtained results are summarized as follows : 1) In case of secondary superheater tube, the fractograph of dimple is observed at the concentration of $H_2SO_4$-5%. When the concentration of $H_2SO_4$ is above 10%, the fracture mode is shifted from a transgranular fracture to an quasi-intergranular fracture according to the increment of concentration. 2) In the relationship between [$\Delta$DBTT]$_sp$ and SCC susceptibility, it is confirmed that the greater material degradation degree is, the higher SCC susceptibility is. In addition, it can be known that SP test is useful test method to evaluate SCC susceptibility for high temperature structural components. 3) When [$\Delta$DBTT]$_sp$ is above 17$17^{\circ}C$ the SCC fracture behavior is definitely observed with SCC susceptibility of above 0.4.

• 한국수산과학회지
• /
• 제20권2호
• /
• pp.146-151
• /
• 1987

정어리유의 산화 안정성과 지질추출시에 첨가한 BHA에 의한 저장중의 산화방지효과를 정토하고 산화로 인한 지방산 조성의 면화를 조사한 결과를 요약하면 다음과 같다. 1. BHA는 유리 지방산의 생성을 현저히 억제하는 효과가 있었다. 2. BHA는 과산화물 생성을 억제하였으며 특히 카르보닐 화합들의 생성을 아주 강하게 억제하였다. 즉 BHA는 과산화을 분해를 억제하는 작용이 있었다. 3. 정어리유는$C_{20:5}$와 $C_{22:6}$의 함량이 $23\%$ 이상으로서 매우 높았다. 4. 산화에 의한 지방산의 감소는 polyene 산에서 급격하였으며 특히 $C_{20:5}$와 $C_{22:6}$산이 급격히 감소하였다. BHA 첨가는 $C_{22:5}$와 $C_{22:6}$산의 산화를 크게 억제 할수 있었다.

• 생명과학회지
• /
• 제21권11호
• /
• pp.1599-1606
• /
• 2011

유류분해에 있어 혼합미생물제제의 효과를 평가하기 위해 미생물제제의 처리성능과 microcosm test를 수행하였다. 유류분해세균은 0.5% Arabian heavy crude oil을 유일 탄소원으로 제공된 최소배지를 이용한 연속적인 농후배양을 통하여 분리하였다. 우수 유류분해 미생물조합인 3종의 균주(BS1, BS2, BS4)는 MSM배지에서 5일의 배양기간 동안 지방족 탄화수소를 48.4%, 방향족 탄화수소를 30.5% 생분해하였다. 처리성능 및 microcosm test는 Arabian heavy crude oil을 첨가한 후 3가지 처리조건인 무처리, 무기영양염처리 그리고 무기영양염 및 혼합미생물처리조건에서 유류화합물의 생물분해에 미치는 영향을 조사하였다. 무기영양염처리구와 무기영양염 및 혼합미생물처리구에서 지방족 탄화수소의 분해율은 실험기간 동안 유의하게 향상되었으며 두 실험구간 유의한 차이는 관찰되지 않았다. 그러나 무기영양염 및 혼합미생물처리구에서 방향족 탄화수소의 생분해율은 무기영양염제만을 처리한 시험구와 비교하여 처리성능 시험의 경우 50% 그리고 microcosm test의 경우 13%를 향상시켰다. 본 연구의 결과로부터 혼합미생물제제는 실험실, 처리성능 및 microcosm test에서 지방족뿐만 아니라 방향족 탄화수소의 생물분해를 촉진하였다. 특히 혼합미생물제제는 방향족 탄화수소의 제거를 위한 생물정화기술의 적용에 있어 유용한 도구로 판단된다.

• 환경위생공학
• /
• 제15권4호
• /
• pp.123-133
• /
• 2000

The kinetic analysis was carried out for commercial rubbers such as NR, IR, BR, SBR 1500, and SBR 1700. Kinetic analysis for the commercial rubbers was performed using the thermogravimetric method, with which the activation energies of NR obtained by Kissinger, Friedman, and Ozawa's method were 195.0, 198.3 and 186.3kJ/mol, whereas that of SBR 1500 were 246.4, 247.5 and 254.8kJ/mol, respectively. It was shown that the yield of pyrolytic oil was generally increased with final temperature increasing, yet slightly decreased or increased over $700^{\circ}C$. Considering the effect of heating rate, it was found that the yield of pyrolytic oil was not consistent for each sample. The number average molecular weight of SBR 1500 was in the range of 740~2486. The calorific value of SBR 1500 was 39~40kJ/g, which were made comparative study of the conventional fuel such as kerosene, diesel, light fuel, and heavy fuel. Therefore it was essential that the selection of the suitable kinetic model and the mathematical solution because of the difference in parameters obtained from each method. It was proposed that the range of $600~700^{\circ}C$ in final temperature and high heating rate due to short run time. It was suggested that the pyrolytic oil be available to use to the fuel.

• 한국물환경학회지
• /
• 제22권5호
• /
• pp.824-830
• /
• 2006

Several tests were conducted to optimize the design parameters of ln-situ soil flushing processes for diesel contaminated soil. According to the batch extraction test for three anionic surfactants evaluation, Calgonit limiting bubble occurrence was selected for its higher oil cleaning efficiency. After optimum surfactant selection, there were many sets of column flushing test. Over 70% of BTEX was removed in this surfactant dose with 400% of soil volume. In the case of no surfactant addition flushing in column, so called "blank flushing test", BTEX removal rate was 64%. But when we reused the effluent for the cleaning solution, the removal rate was decreased to 46.9%. This result showed reabsorption of oil occurred on the soil. With the addition of Calgonit solution to the diesel contaminated column, BTEX was removed up to 98.9% during the first flushing and 99.4% for the second recirculation flushing. In microcosm tests, diesel contaminated soils were cleaned by both surfactant flushing and biological activities. In anoxic condition, nitrate was used as an electron acceptor while the surfactant and the oil were used an electron donor. BTEX removal efficiency could be achieved up to 80% by biological degradation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
• /
• pp.76-78
• /
• 2005

Moisture contents measurement is frequently used as one of parameters for degradation diagnosis of transformer insulation. In general Karl-Fisher method is mainly used for moisture contents till now. But this method is inconvenient because of dismounting transformer for sampling oil or paper, and also partial sampling. At latest Recovery Voltage Method(RVM) is noticed for complement of this method. RVM can directly estimate moisture contents of transformer insulations in field without dismounting transformer. In this paper the accelerated aging process of oil-paper samples have been investigated at a temperature up to 140$^{\circ}C$ for 500 hours. The oil-paper insulation samples have been measured at intervals of 100 hours. Next to, we have estimated moisture contents using both Karl-Fisher Titration Method and RVM. And we have compared with Karl-Fisher Titration Method and RVM for estimating moisture contents. At last we have verified reliability of RVM which is new measurement method.