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Ga 로 변형된 HZSM - 5촉매상에서 n - 헥산의 방향족과 반응
이준원,박용철,이현구 ( Jun Won Lee,Yong Chul Park,Hyun Ku Rhee ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.1
Since the species Ga in Ga/HZSM-5 would be converted to Ga₂O₃(the most stable oxidized state) if calcined in air, HZSM-5 was mixed mechanically with Ga₂O₃and applied to the conversion of n-hexane. The experimental results of the catalytic reaction was compared with those over Ga/HZSM-5 catalyst. The mixture catalyst was also characterized by TEM and TPD analysis. These results were combined together to elucidate the relationship between the acid sites of HZSM-5 and active gallium species. Also, gallosilicate was synthesized by introducing Ga into the framework and applied to the conversion of n-hexane. Investigated here were the BTX selectivity, the influence of the calcination temperature and the effect of Ga-impregnation. This information was then correlated with the catalytic characteristics of gallosilicate to examine the active site for aromatization reaction.
변형된 ZSM - 5 촉매상에서 n - 헥산의 방향족화 반응에 관한 연구 2 . Ga/HZSM - 5 촉매상에서 - N - 헥산의 방향족화 반응
이준원,이현구 ( Jun Won Lee,Hyun Ku Rhee ) 한국화학공학회 1995 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.33 No.2
HZSM-5 catalyst was synthesized and modified by impregnating Ga. The modified catalyst was then applied for the aromatization of n-hexane to give rise to a substantial improvement in the selectivity to aromatics. The aromatics were observed even over Ga/HZSM-5 of high Si/Al ratio. The aromatics turned out to be the secondary product in contrast to their being tertiary product over HZSM-5. With respect to the aromatics formation the primary and major product was found to be toluene over Ga/HZSM-5 of low Si/Al ratio whereas it was benzene over Ga/HZSM-5 of high Si/A1 ratio. Evidently, this feature was related to the ratio of the amount of propylene to that of C4-hydrocarbons in the reaction mixture. The hydrogen production was significantly increased by the introduction of Ga regardless of the formation of aromatics. By virtue of the Ga`s role of hydrogen scavenger more olefins were formed by cracking reactions and the dehydrocyclization seemed to be promoted. Apparently, this gave rise to the enhancement of the aromatizing activity. From these results the reaction pathways were deduced for the n-hexane conversion over bifunctional Ga/HZSM-5 catalyst and compared with those over HZSM-5 catalyst.
Hysteresis PWM 전류 제어 기법을 사용한 독립 다상 BLDC 전동기의 효율 해석 유효성 검증
이준원,공영경,박선정,최호용,홍성영,Lee, Junewon,Kong, Yeongkyung,Park, Sunjung,Choi, Hoyong,Hong, Sungyoung 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.5
In this paper, the analysis and the experiment of independent multi-phase BLDC motor are performed. The back-emf, iron loss analysis are performed by the finite element method and compared with experimental results. The independent multi-phase BLDC motor is manufactured and to measure the efficiency of the motor, evaluation system is also manufactured including the load generator. By comparing the analytic and the experimental results, the effectiveness of the analysis model is verified when calculating the efficiency of the motor.
변형된 ZSM - 5 촉매상에서 n - 헥산의 방향족화 반응에 관한 연구 1 . HZSM - 5 촉매의 Si / Al 비의 영향
이준원,이정규,이현구 ( Jun Won Lee,Jeong Kyu Lee,Hyun Ku Rhee ) 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.2
ZSM-5 catalyst was synthesized with various Si/Al ratios and applied for the aromatization of n-hexane. Over HZSM-5 catalyst, n-hexane was first cracked to yield C₁-C_5 hydrocarbons, of which propylene and C₄ were converted to aromatics via secondary reactions. Aromatics were observed over HZSM-5 catalysts of Si/Al ratios below 100 and the selectivity to aromatics increased with the temperature. Among aromatics, toluene was the major product. The reaction pathways were deduced by analyzing each reaction step of cracking and aromatization in connection with the Si/Al ratio and the reaction temperature. Based on these results, favorable conditions for the aromatization of n-hexane over HZSM-5 catalyst were investigated.
무강수일수와 강우효과를 고려한 개선된 표준강수지수 개발
이준원,김광섭,Lee, Jun-Won,Kim, Gwang-Seob 한국수자원학회 2012 한국수자원학회논문집 Vol.45 No.4
본 연구에서는 가뭄의 심도에 직접적으로 영향을 주는 무강수일수를 고려하고, 강수에서 기인하는 지표면유출 효과를 반영한 가뭄해갈에 유효한 강수를 산정하여 기존의 SPI3을 개선한 Modified SPI를 제시하였다. 1973년부터 2009년까지 각종 보고서 및 문헌자료를 통해 실제 발생한 가뭄사례를 수집하여 행정구역별 가뭄공간정보를 생산하고, 동일기간 전국 69개지점에서산정된 가뭄지수를 우리나라 전체 공간으로표현하여각종 지수의 적합성을 평가하기 위하여ROC 분석을 수행하였다. 개선된 가뭄지수 제시를 위하여 총 강우량 중단기적인 유출에 기여할 것으로 판단되는 부분을 절삭하여 유효강우를 산정하였으며, 월단위의 무강수일수를 십분위, 누적분포함수로 변형하여 기존의 지수에 가중치를 부여하였다. 분석결과 유출량을 고려한 강우의 절삭은 기존의 SPI3에 비하여 상대적으로 높은 가뭄감지능력을 보여주었으며, 무강수일수를 고려한 가뭄지수의 개선은 누적분포함수의 수치를 고려함으로서 상당히 개선된 가뭄감지 능력을 보여주었다. A modified standardized precipitation index was developed by considering the length of dry period and surface run-off effect. The official reports and newspapers on drought from 1973 to 2009 were quantified to evaluate drought indices. The developed index was evaluated using the receiver operating characteristic analysis. In order to suggest improved drought index, we cut the precipitation amount that may do not contribute the mitigation of drought and weight dry period by considering cumulative distribution, decile distribution of dry periods. Drought detection capability of the suggested index has improved by weighting of dry period effects and considering precipitation amounts contributing drought mitigation.