• 한국토양환경학회지
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• 제5권1호
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• pp.97-108
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• 2000

원유를 탄소원으로 이용할수 있는 그람 음성 박테리아가 도시하수 처리장의 활성슬러지로부터 단리되어 Acinetobacter속으로 동정되었다. 이 균은 원유중의 알칸과 미확인된 다종의 한화수소를 분해할 수 있었으며 소수성 기질인 알칸을 단일 탄소원으로 이용하여 증식할수 있었다. 원유중 탄소수 13-30의 알칸은 동시에 분해가 진행되었으며 한소수의 짝수, 홀수에 따른 분해특성의 차이는 보이지 않았다. 균의 선형적인 증식과 알칸 성분의 분해특성으로부터, 원유상에서 기질의 초기 산화가 진행되는 미생물부위까지 물질전달이 분해과정의 율속이 됨을 알수 있었다. 분해 진행후 반응계내 알칸의 잔류 현상이 관찰되었는데 이는 Acinetobacter 속의 특성으로 알려져있는 세포내 탄화수소 함유체의 영향으로서 원유로 부터의 물질전달을 제어하는 요인이 될수 있음을 시사하였다. 따라서 본 균은 환경중 잔류하는 소수성 오염물질의 분해메카니즘 연구에 중요한 역할을 한다고 사료된다.

• Korean Chemical Engineering Research
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• 제61권4호
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• pp.591-597
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• 2023

Pakistan depends heavily on imports for its fuel requirements. In this experiment, catalytic pyrolysis of a blend of feedstock's consisting of date seed, wheat straw, and corn cob was conducted in a fixed bed reactor to produce oil that can be used as an alternative fuel. The main focus was to emphasize the outcome of important variables on the produced oil. The effects of operating conditions on the yield of bio-oil were studied by changing temperature (350-500 ℃), heating rate (10, 15, 20 ℃/min), and particle size (1, 2, 3 mm). Moreover, ZnO was used as a catalyst in the process. First, the thermal degradation of the feedstock was investigated by TGA and DTG analysis at 10 ℃/min of different particle sizes of 1, 2, and 3mm from a temperature range of 0 to 1000 ℃. The optimum temperature was found to be 450 ℃ for maximum degradation, and the oil yield was indicated to be around 37%. It was deduced from the experiment that the maximum production of bio-oil was 32.21% at a temperature of 450 ℃, a particle size of 1mm, and a heating rate of 15 ℃/min. When using the catalyst under the same operating conditions, the bio-oil production increased to 41.05%. The heating value of the produced oil was 22 MJ/kg compared to low-quality biodiesel oil, which could be used as a fuel.

• Journal of Microbiology and Biotechnology
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• 제14권5호
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• pp.901-905
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• 2004

The degradation and mineralization of crude oil were investigated over 50-days in three soils, loamy sand, sand, and combusted loamy, which were artificially contaminated with crude oil (50 g $kg^{-1}$) and inoculated with Nocardia sp. H17-1. The degradation efficiency of total petroleum hydrocarbon (TPH) in sand was the highest at 76% among the three soils. The TPH degradation rate constants $(k_{TPH})$ in loamy sand, sand, and combusted loamy sand were 0.027 $d^{-1}$, 0.063 $d^{-1}$, and 0.016 $d^{-1}$, respectively. In contrast, the total amount of $CO_2$ evolved was the highest at 146.1 mmol in loamy sand. The $CO_2$ evolution rate constants (k_{CO2})$ in loamy sand, sand, and combusted loamy sand were 0.057 $d^{-1}$, 0.066 $d^{-1}$, and 0.037 $d^{-1}$, respectively. Therefore, it seems that the degradation of crude oil in soils can be proportional to the soil pore space and that mineralization can be accelerated with the increase of organic substance.

• 대한방사선기술학회지:방사선기술과학
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• 제2권1호
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• pp.71-83
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• 1979

Not only the insulating oil used for extra high voltage and high capacity transformer has a lot of possibilites of a corona discharge in oil, but the oil is easily degraded by a response of light oxidization. This study is either to classfy, with priority given to a transformer oil produced in Korea belonging to, the insulating oil No. 2, the sample irradiated the ultraviolet rays, treated a corona discharge in oil by a high voltage DC source and done nothing, or to measure the characteristics of breakdown, V-i, I-t and electrode material. The obtained results can be summarized as followings: (1) Unless the sample is contacted with the air, on the process to irradiate the ultraviolet rays, the sample less influence on the changes of the electric characteristics. At the same time, if the sample is contacted with the air and irradiated the ultraviolet rays, the sample shows a remarkable changes of the electric characteristics, and a declined breakdown strength. This tells us that the influence of the light irradiation must be considered as a primary factor of degrading the insulating oil. (2) In the oil treated by a corona discharge, breakdown voltage is declined more than in the oil not to be treated with it. This means that the degradation of the insulating oil is getting increased by a corona discharge in oil. (3) It shows that the increase of conducting current has little to do with breakdown voltage. (4) The conducting current depending on the electrode materials can be put in order by value as Al>Cu>Fe. This is due to the differences of the work function of each metals, and an chemical reaction with the insulating oil. These result can be a great help in verifying the degradation progress of the insulating oil and furnish a new technical information to the manufacturers of the insulating oil and electrical equipment designers and operators. Besides, this study would be helpful to improve the electrical characteristics of the insulating oil produced in Korea.

• 전기학회논문지
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• 제65권9호
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• pp.1518-1523
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• 2016

In this study, in order to understand the degradation characteristics of oil-paper insulation for power transformers and OF cables, tan delta was measured using cable model specimens with long-term accelerated thermal and electrical aging. In addition, to find out the degradation level due to the accelerated aging, tensile strengths of aged papers were measured. As a result, tan ${\delta}$ showed the characteristics of slight decrease at the first stage and then increase with the aging time, which could be analyzed due to the evaporation of remaining moisture and the change of aging rate with time. Also, the trend of tensile strengths with aging temperature and time was appeared to be exponentially decreased and by use of these data equivalent calculated lifetimes and accelerated aging factors were derived for each aging temperatures. After then, tan ${\delta}$ was analyzed with the equivalent operating years. For all different aging temperatures, the aged data were very well fit to the equivalent operating years and it is shown that tan ${\delta}$ was increased with the decrease of tensile strength.

• 한국미생물·생명공학회지
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• 제31권4호
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• pp.408-412
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• 2003

오염토양에 유류분해능을 가진 Nocardia sp. H17-1의 접종시 고려되어야 할 인자중 하나인 초기 오염농도에 의한 탄화수소분해능과 초기 접종농도에 의한 분해능 및 균주의 생육을 조사하였다. H17-1은 실험 50일 동안 초기 오염농도 10, 50, 100 g Arabian light oil/kg of soil에 대해 각각 78.5%, 94.3%, 53.2%의 탄화수소를 제거하였으며, 오염농도가 높을수록 분해속도 상수(k) 낮아졌다. $CO_2$의 생성량 또한 오염농도가 높을수록 증가하였으나, 100 g/kg-soil의 오염농도에서는 균의 생육이 저해를 받는 것으로 나타났다. H17-1의 초기 접종농도에 의한 영향은 균의 접종량에 따라 최종 남은 TPH의 양은 큰 차이를 나타내지 않았으나, 분해속도상수(k)는 균의 접종량이 늘어남에 따라 크게 증가되었으며, $CO_2$의 생성량 또한 균의 접종농도에 따라 증가하였다.

• 한국토양환경학회지
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• 제4권3호
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• pp.95-104
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• 1999

소수성 오염물질인 원유성분의 분해메카니즘을 규명하기 위하여 원유중 알칸성분의 동시분해능을 지닌 Acinetobacter sp. 를 단리하여 액체/고체알칸, 서로다른 고체알칸을 단일 또는 복합기질로 하여 비교분해연구를 행하였다. 또한 비분해성 유기액상성분인 pristane을 원유매체, 고체알칸인 heneicosane을 유효기질로 하는 실험계를 확립하여 원유성분의 분해모델로서 연구를 행하였다. 본 연구에 이용된 Acinetobacter sp. 는 기질의 물리적 상태가 다른 액체/고체 성분의 분해특성에 차이를 보이지 않고 소수성기질의 표면에 직접접촉하여 분해할수 있음을 시사하였으며, 서로 다른 고체알칸의 단일 또는 복합 분해연구와 탄화수소에 대한 미생물의 부착성 결과가 이를 믿바침하였다. 또한 고체성분이 원유중에서는 유기상내에 용존상태로 존재함에 착안한 heneicosane/pristane계의 연구결과 원유매체는 미생물로의 유효기질 전달을 억제함을 밝혔으며, 단일성분으로 존재할때에 비하여 분해가 일어나기 위한 미생물과의 접촉면적을 감소시키는 유효기질의 비표면적 저하가 주요 원인임을 알 수 있었다.

• 농업과학연구
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• 제37권3호
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• pp.465-469
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• 2010

In order to develop effective recycling technologies of disused railway wood ties, wood properties and residual creosote oil of wood ties were investigated. Among the total 50 wood ties, 32 wood ties were identified as tropical hardwood tree, such as, Keruing (Dipterocarpus spp.), Kempas (Koompassia malaccensis), Kapur (Dryobalanops spp.) Naytoh (Palaquium rostratum), and so on. Disused wood ties showed mostly sound structure without degradation of cell walls by decay fungi. Disused wood ties showed high strengths of bending and compressive parallel to grain because degradation of wood properties was hardly occurred in use under exterior condition. Disused railway wood ties had relatively poor depth of penetration and residual of creosote oil because of refractory wood structures. These results suggest that disused railway wood ties may be useful as recycling wood wastes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1563-1565
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• 2000

This paper presents the preliminary results on the application of optical fiber sensor(OFS) for the diagnosis of degradation in the transformer oil. An OFS system using a Mach-Zehnder interferometry technique was built to detect attenuation of acoustic signal produced by discharging. With increasing the number of discharging in the insulation oil, the attenuation of acoustic signal became greater. A strong correlation between electrical and acoustic signal intensities from discharge generated in the transformer oil was confirmed by the results reported here.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.574-574
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• 2005

To found out the degradation characteristic of transformer insulation, insulation material was depisited into transformer oil and heated. Due to the thermal stress which added to insulation, the density of carbon dioxide which included in transformer oil was mesured by using the gas density detection equipment of gas sensor and air circulation method. As a result, it didn't match with the transformer supervision standard. But it was found that as thermal stress increased, the density of carbon dioxide propertionally increased.