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WO<sub>x</sub>/SBA-15 촉매와 과산화수소를 이용한 선박용 경유의 산화 탈황 연구
오현우 ( Hyeonwoo Oh ),김지만 ( Ji Man Kim ),허광선 ( Kwang-sun Huh ),우희철 ( Hee Chul Woo ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.4
선박용 경유(황 농도 약 230 ppmw)의 황화합물 제거를 위해 산화텅스텐(WO<sub>x</sub>)을 실리카로 이루어진 다공성 물질인 SBA-15에 담지한 산화 촉매를 제조하였으며 산화제로 과산화수소를 이용한 산화공정과 추출 용매로 아세토니트릴을 이용한 추출공정을 통해 촉매의 산화성능을 확인하였다. XRD 및 XRF, XPS 분석과 BET 이론을 통해 제조한 촉매의 물리적 특성에 대해 조사하였다. 담지된 WO<sub>x</sub>는 삼산화텅스텐(WO<sub>3</sub>)으로 존재하였으며 실제 담지율이 약 10 wt% 부근일 때 단일층을 형성하는 것으로 판단된다. 제조한 촉매의 산화성능을 확인한 결과, 0.1 g의 13 wt% WO<sub>x</sub>/SBA-15 촉매와 과산화수소(산소/황 몰 비=10)를 도입하여 90°C에서 3시간 동안 반응이 이루어졌을 때 76.3%의 가장 높은 황제거율을 나타냈다. 연속반응 비교 실험을 통해 1회의 산화반응으로 황 화합물의 산화가 충분히 일어났음을 확인하였다. 또한 5회의 추출공정을 통해 최대 94.4%의 황 제거율을 나타냈다. In this work, tungsten oxide (WO<sub>x</sub>) supported on SBA-15 (mesoporous silica) were prepared and applied for oxidative desulfurization of sulfur compounds in marine diesel containing about 230 ppmw of sulfur concentration. Prepared catalysts were examined by two steps; at first step, oxidation reaction carried out with hydrogen peroxide as oxidant and then the oxidized sulfur compounds were extracted by acetonitrile as solvent. Catalysts were characterized by using X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and N<sub>2</sub> adsorption-desorption isotherms. Tungsten oxide exists as monoclinic crystal system on SBA-15 and over about 10 wt% of the WO<sub>x</sub> loading took the form of multi-layers on SBA-15. The 13 wt% WO<sub>x</sub>/SBA-15 catalyst exhibite highest activity, achieving about 76.3% sulfur removal in the reaction conditions, such as catalyst amount of 0.1 g, reaction temperature at 90 °C, reaction time for 3 h and O/S molar ratio of 10. One time oxidation reaction is enough oxidize the sulfur compounds in marine diesel completely. The repetition experiment of extraction process indicated that sulfur removal could reach 94.4% after 5 times.
Hyeonwoo Shin,Jin Woo Oh,김영진,Jeong Gon Son,Changhee Lee,Keun-Young Shin 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.81 No.-
A highly transparent and high-performance random-network single-walled carbon nanotubes (r-SWCNTs) transistor was successfully fabricated by using chemical vapor deposition-grown graphenesource/drain (S/D) electrodes. The bottom-gate, bottom-contact geometry was selected for the grapheneS/D contact r-SWCNT (Gr-SWCNT) transistor because of its enhanced gate modulation and goodsustainability. A palladium S/D contact r-SWCNT (Pd-SWCNT) transistor with the same device geometrywas also fabricated for a comparative study. The transmission line method demonstrated that theresistivity of graphene was small enough ( 0.95 V mm) to be used as S/D electrodes in a single transistordevice, and the contact resistance of Gr-SWCNTs was much lower than that of Pd-SWCNTs. Particularly,the correlation between the applied gate voltage and the sheet resistance is strongly dependent on the r-SWCNTfilm density. The resulting Gr-SWCNT transistor exhibits high mobility and good on/off currentratio compared to the Pd-SWCNT transistor. The high charge injection originated from the ohmic contactbehavior and dense r-SWCNT channel formation by the enhancement of selective wetting due to thesurface energy matching between the r-SWCNT semiconductor and graphene S/D electrodes. Thus, thisapproach can encourage creating highly transparent and high-performance carbon-basedfield effecttransistor.
오상용,임현우,구정완,정치경,윤임중 가톨릭대학산업의학센타 산업의학연구소 1998 韓國의 産業醫學 Vol.37 No.4
In order to study the effect of smoking on pneumoconiosis patients, two forced expiratory spirograms were performed 4 years apart on 35 office workers (Control group) and 86 pneumoconiosis patients. Comparison of ventilatory indices such as FEV₁, ??, and ?? were done by analyzing two forced expiratory spirograms which were measured by Autobox system(Model Cs-828 Fc, Chest Co., Japan). 1. In the initial pulmonary fuction tests there was no significant difference between smokers and ex-smokers in the control group. On the other hand smokers in the patient group showed significantly lower mean value of %FEV₁ compared to ex-smokers(p<0.05). The differences of %FEV₁, ??, ??% during 4 years also showed no significant differences between smokers and ex-smokers in the control group but were significantly lower in smokers compared to ex-smokers in pneumoconiosis patients(p<0.05). 2. Smoking decreased the ventilatory indicies in all pneumoconiosis patients. Also when smoking was continued, decrease of the ventilatory indices was more related to progression than change of type in pneumoconiosis. But there were no significant differences between ex-smokers with non-progressive pneumoconiosis and ex-smokers with progressive pneumoconiosis. 3. When differences in ventilatory indices during 4 years were analyzed according to type or category of pneumoconiosis, comparison of smokers and ex-smokers did not show any regular tendency. With the above considerations it is suggested that smoking has an influence on pulmonary function of the non-progressive pneumoconiosis patients, and progressive pneumoconiosis patients. Furthermore smoking has more deletrious influence on pulmonary function in progressing pneumoconiosis patients than that in stability pneumoconiosis patients. As a result, to prevent worsening of pulmonary function in pneumoconiosis patients, encouraging them to quit smoking is very important.
기존 무도상 판형교 하부기초 지지력 및 근입 깊이 현장평가
유현우(Yoo, Hyeonwoo),오정호(Oh, Jeongho),안신환(Ahn, Sinwhan) 한국방재학회 2021 한국방재학회논문집 Vol.21 No.1
국내 철도교량 중 급속교체 대상교량인 무도상 판형교는 유도상 구조를 갖추는 과정에서 일반적으로 장대레일을 설치하게 된다. 장대레일 특성 상 온도변화에 의한 축력이 부가되며, 이는 기존의 무도상 판형교 하부기초가 분담하게 된다. 운용중인 무도상 판형교는 대부분 50년 이상된 구조물로 설계 자료 확보가 어려운 무상기초 형태가 많으므로, 하부기초의 구조적 건전도 및 제원을 파악하는 것이 매우 중요하다. 본 연구에서는 지반조사 시 통상적으로 시행되는 표준관입시험과 현장 접근성 및 경제성이 우수한 중형공압콘관입시험법을 활용하여 무상기초 지지력을 평가할 수 있는 상관관계를 도출하고자 하였으며, 상기 두 시험법을 가진원으로 하여 무상기초의 근입 깊이를 추정할 수 있는 탄성파 시험법을 제안하고자 현장시험을 수행하였다. 현장실험 결과, 타격 에너지를 보정한 중형공압콘관입시험 측정치는 표준관입시험 측정치와 유의한 관계를 보였다. 또한, 제안된 탄성파 시험을 통해 무상기초를 모사한 PVC 및 강관 파이프를 매설한 지반 조건에서 원지반 대비 전단파 수신 신호 크기가 저감되는 것을 확인하였으며, 이는 무상기초의 근입 깊이를 추정하는데 유효할 것으로 판단된다. The ballastless plate girder bridge, classified as a structure type that requires an emergent replacement among domestic railway bridges, generally tends to upgrade to a ballasted track along with continuous welded rail (CWR). The axial forces of the CWR due to the temperature change need to be distributed to the bridge foundations. Because most of the existing ballastless plate girder bridges of over 50 years of age do not provide any design information, such bridge foundations are regarded as unknown foundations, and therefore, it is crucial to identify the structural adequacy and dimension. In this study, an effort was made to establish a correlation between the standard penetration test (SPT) and mid-size pneumatic cone penetration test (MPCP) to estimate the load bearing capacity of an unknown foundation. A field test was conducted to estimate the depth of the unknown foundation by employing SPT and MPCP as the source wave part. The magnitude of the shear wave was mitigated by the presence of PVC and steel pipes, such that it might be possible to identify the embedment depth of unknown foundations.