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유류 오염 토양에서 분리된 Rhodococcus fascians를 이용한 해수에서의 디젤유의 분해
구자룡(Ja-Ryong Koo),문준형(Jun Hyung Moon),윤현식(Hyun Shik Yun) 한국생물공학회 2009 KSBB Journal Vol.24 No.5
본 실험에 사용된 균주는 유류로 오염된 지역의 토양시료로부터 직접 분리한 Rhodococcus fascians로 이전 연구에서 항공유의 분해에 효과가 있는 것으로 밝혀진 균주이다. 디젤유가 항공유보다 R. fascians의 생장에 영향을 주는 것으로 나타났다. 해수중의 디젤 분해를 위해서는 2%이상의 접종량이 효과적이며 접종량이 증가할 경우 잔류량이 더 감소하였으나 큰 차이는 없었다. 해수중의 디젤이 5% 이상에서는 디젤유의 독성에 의해 R. fascians의 생장이 저해를 받아 디젤 잔류량이 높게 나타났다. R. fascians는 pH 8에서 가장 높은 디젤 분해속도를 보였으며 비교적 넓은 pH 범위에서 디젤 분해도가 유지되는 것으로 나타났다. R. fascians의 최적 성장온도 보다 높은 32℃에서는 디젤의 분해에 온도증가에 따른 자연분해의 영향이 큰 것으로 나타났다. R. fascians의 해수중 디젤유 분해의 최적온도는 27℃로 최적 생장온도에서 분해가 활발히 이루어지는 것을 알 수 있었다. Contamination of marine environment with hazardous and toxic chemicals is more common these days. Bioremediation is the application of microorganism or microbial processes to degrade environmental contaminant. Because of low water solubility and volatility of diesel, bioremediation is more efficient than physical and chemical methods. The objective of this study is biodegradation of diesel in sea water by using Rhodococcus fascians which is isolated petroleum-contaminated soil. R. fascians was cultured on sea water containing diesel to determine the diesel degradability. Changes in biodegradability of diesel with various inoculum sizes, diesel concentrations, initial pH, and culture temperature were analyzed by TPH analysis using gas chromatography. The inoculum size 2% was effective for biodegrdation of diesel in sea water by R. fascians. When diesel concentration was 5%, the growth of cell was inhibited by the toxicity of diesel. The optimal temperature and initial pH for degradation of diesel in sea water were 27℃ and pH 8.
Saccharomyces cerevisiae M3G3를 이용한 1,2-Propanediol의 생산 최적화
구자룡(Ja-Ryong Koo),Nancy A. DaSilva,윤현식(Hyun Shik Yun) 한국생물공학회 2011 KSBB Journal Vol.26 No.5
1,2-propanediol (1,2-PD) is a commodity chemical that is currently produced from petrochemical derivatives. Saccharomyces cerevisiae is well characterized and a successful industrial microorganism to enable the improvement of the 1,2-propanediol production by metabolic engineering. A recombinant S. cerevisiae M3G3 was used to produce 1,2-propanediol. S. cerevisiae M3G3 is the diploid strain that contains 3 copies of mgs (methylglyoxal synthase) and gldA (glycerol dehydrogenase). S. cerevisiae M3G3 was cultivated at various culture conditions by changing culture temperature, glucose concentration, and inducer concentration. Also the effect of induction time was studied to optimize the production of 1,2-propanediol. Batch and fed-batch cultivation of S. cerevisiae M3G3 was performed by using a 5 L jar fermenter. The highest concentration of 1,2-propanediol in batch cultivation was 0.86 g/L and it was further improved to 1.33 g/L in fed-batch cultivation.
Eicosanoic Acid Langmuir-Blodgett(LB) 박막을 이용한 분자 다이오드의 전기적 특성
구자룡 ( Ja Ryong Koo ),이호식 ( Ho Sik Lee ),권혁주 ( Hyuck Joo Kwon ),손병청 ( Byoung Chung Sohn ) 한국유화학회 2003 한국응용과학기술학회지 Vol.20 No.2
N/A Electron transfer through an Langmuir-Blodgett(LB) monolayer film sandwiched between metal electrodes. We used an eicosanoic acid material and the material was very famous as a thin film insulating material. Eicosanoic acid monolayer was deposited by Langmuir-Blodgett(LB) technique and a subphase was a CdCl_2 solution as a 2×10^4 mol/L. Also we used a bottom electrode as an Al/Al_2O_3 and a top electrode as a Al and Ti/Al. Here, the Al_2O_3 on the bottom electrode was deposited by thermal evaporation method. The Al_2O_3 layer was acted on a tunneling darrier and insulating layer in tunnel diode. It was found that the proper transfer surface pressure for film deposition was 25 mN/m and the limiting area per molecule was about 24 A^2/molecule. When the positive and negative bias applied to the molecular device, the behavior shows that a tunnel switching characteristics. This result were analyzed regarding various mechanisms.
온도에 의존하는 전기적 측정을 이용한 분자 메모리 소자의 전하 이동 메커니즘 분석
최경민,구자룡,김영관,권상직,Choi, Kyung-Min,Koo, Ja-Ryong,Kim, Young-Kwan,Kwon, Sang-Jik 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.7
A molecular memory device which has a structure of Al/$Al_2O_3$/ASA-15 LB monolayer/Ti/Al device, was fabricated. To study a charge transfer mechanism of molecular memory devices, current density-voltage (J-V) characteristics were measured at an increasing temperature range from 10 K to 300 K with an interval of 30 K. Strong temperature-dependent electrical property and tunneling through organic monolayer at low bias (below 0.5 V) were appeared. These experimental data were fitted by using a theoretical formula such as the Simmons model. In comparison between the theoretical and the experimental results, it was verified that the fitting results using the Simmons model about direct tunneling was fairly fitted below 0.5 V at both 300 K and 10 K. Hopping conduction was also dominant at all voltage range above 200 K due to charges trapped by defects located within the dielectric stack, including the $Al_2O_3$, organic monolayer and Ti interfaces.